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Mediul wireless transportÄ semnale electromagnetice care reprezintÄ cifre binare pentru comunicaÈiile de date care folosesc frecvenÈe radio sau de microunde. Ca Èi mediu de reÈea, wireless nu este restricÈionat la conductori sau cÄi de acces, aÈa cum sunt mediile din fibrÄ sau cupru. Mediul wireless asigurÄ cele mai bune opÈiuni de mobilitate dintre toate mediile. Astfel, numÄrul de echipamente wireless este Ăźn continuÄ creÈtere. Din aceste motive, wireless a devenit o opÈiune pentru toate reÈelele de domiciliu. Pe mÄsurÄ ce opÈiunile lÄÈimii de bandÄ cresc, wireless creÈte Ăźn popularitate Ăźn reÈelele companiilor. Figura evidenÈiazÄ cĂąteva simboluri cu privire la wireless. Ăn orice caz, wireless-ul are cĂąteva zone de preocupare precum: âą Aria de acoperireTehnologiile de comunicare a datelor wireless funcÈioneazÄ bine Ăźn mediile deschise. Ăn orice caz, unele materiale de construcÈie folosite Ăźn structuri Èi clÄdiri Èi terenul local vor limita aria de acoperire. âą InterferenÈaWireless-ul este predispus la interferenÈe Èi poate fi Ăźntrerupt de echipamente obiÈnuite cum ar fi telefoane fÄrÄ fir, unele tipuri de luminÄ fluorescentÄ, cuptoare cu microunde Èi alte comunicaÈii wireless. âą SecuritateaAcoperirea comunicaÈiei wireless nu necesitÄ acces fizic la mediu. AÈadar, echipamentele Èi utilizatorii care nu au autorizaÈie pentru a accesa reÈeaua pot obÈine accesul la transmisie. Ăn consecinÈÄ, securitatea reÈelei este o componentÄ principalÄ pentru administrarea reÈelei wireless. DeÈi wireless-ul creÈte Ăźn popularite pentru conectivitatea calculatoarelor, fibra Èi cuprul sunt cele mai populare medii ale layer-ului fizic pentru dezvoltarea reÈelelor. Tipuri de Mediu Wireless IEEE Èi standardele industriei de telecomunicaÈii pentru comunicarea wireless a datelor acoperÄ atĂąt layer-ului fizic, cĂąt Èi layer-ul data link. ExistÄ patru standarde uzuale de comunicare a datelor care se aplicÄ mediului wireless: âą Standard IEEE 802.11Tehnologia WLAN (Wireless LAN), denumitÄ Èi Wi-Fi, foloseÈte un sistem nedeterminist sau controversat cu un proces de acces la mediu CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance). âą Standard IEEE 802.15Standardul WPAN (Wireless Personal Area Network), cunoscut Èi ca "Bluetooth", foloseÈte un proces de Ăźmperechere a echipamentelor pentru a comunica pe distanÈe cuprinse Ăźntre 1 Èi 100 metri. âą Standard IEEE 802.16CunoscutÄ de obicei ca WiMAX (Worldwide Interoperability for Microwave Access), foloseÈte o topologie de tip point-to-multipoint pentru a furniza acces broadband de tip wireless. Figura evidenÈiazÄ cĂąteva diferenÈe ale mediilor wireless. NotÄ:Celelalte tehnologii wireless cum ar fi comunicaÈiile prin satelit Èi celulare pot asigura Èi ele conectivitatea reÈelei de date. Ăn orice caz, aceste tehnologii wireless depÄÈesc scopul acestui capitol. Ăn fiecare din exemplele de mai sus, specificaÈiile layer-ului fizic sunt aplicate zonelor care includ: âą Codificarea semnalului radio sau de date âą FrecvenÈa sau puterea de transmisie âą RecepÈia semnalului sau cerinÈele de decodificare âą ConstrucÈia Èi design-ul antenei NotÄ:Wi-Fi este marcÄ ĂźnregistratÄ Wi-Fi Alliance. Wi-Fi este utilizat ĂźmpreunÄ cu produse certificate care aparÈin echipamentelor din WLAN bazate pe standardele IEEE 802.11. LAN Wireless O implementare uzualÄ wireless a datelor este permiterea echipamentelor sÄ se conecteze prin wireless la un LAN. Ăn general, un LAN wireless necesitÄ urmÄtoarele echipamente de reÈea: âą Puncte de Acces Wireless (AP)ConcentreazÄ semnalele wireless de la utilizatori Èi se conecteazÄ, de obicei printr-un cablu de cupru la infrastructura de reÈea existentÄ bazatÄ pe cupru, cum ar fi Ethernet. Routerele wireless din companiile mici sau de domiciliu integreazÄ funcÈiile unui router, switch Èi punct de acces Ăźntr-un echipament, aÈa cum se aratÄ Ăźn figurÄ. âą PlÄcile de reÈea wirelessAsigurÄ capacitatea de comunicare wireless la fiecare host de reÈea. AvĂąnd Ăźn vedere cÄ tehnologia s-a dezvoltat, a apÄrut un numÄr de standarde WLAN bazate pe Ethernet. Este necesarÄ atenÈia atunci cĂąnd se achiziÈioneazÄ echipamentele wireless pentru a asigura compatibilitatea Èi interoperabilitatea. Beneficiile tehnologiilor de comunicare a datelor wireless sunt evidente, Ăźn special convenienÈa ce reiese din mobilitatea hostului Èi reducerea costurilor necesare cablÄrii. Ăn orice caz, administratorii de reÈea trebuie sÄ dezvolte Èi sÄ aplice politici de securitate Èi procese pentru a proteja LAN-urile wireless Ăźmpotriva accesului neautorizat Èi a defecÈiunilor. Standardele 802.11 Wi-Fi Ăn ultimii ani au fost dezvoltate mai multe standarde 802.11. Standardele includ: âą IEEE 802.11aFuncÈioneazÄ pe banda de frecvenÈÄ de 5 GHz Èi oferÄ viteze de pĂąnÄ la 54 Mb/s. Deoarece acest standard funcÈioneazÄ la frecvenÈe Ăźnalte, are o arie de acoperire micÄ Èi este mai puÈin eficientÄ la penetrarea structurilor construcÈiilor. Echipamentele care funcÈioneazÄ Ăźn cadrul acestui standard nu sunt interoperabile cu standardele 802.11b Èi 802.11g descrise mai jos. âą IEEE 802.11bFuncÈioneazÄ pe banda de frecvenÈÄ de 2.4 GHz Èi oferÄ viteze de pĂąnÄ la 11 Mb/s. Echipamentele care implementeazÄ acest standard au o arie mai mare Èi pot pÄtrunde mai bine Ăźn structurile clÄdirilor decĂąt echipamentele bazate pe 802.11a. âą IEEE 802.11gFuncÈioneazÄ pe banda de frecvenÈÄ de 2.4 GHz Èi oferÄ viteze de pĂąnÄ la 54 Mb/s. Echipamentele care implementeazÄ acest standard funcÈioneazÄ la aceeaÈi frecvenÈÄ de radio Èi arie ca Èi 802.11b dar cu lÄÈimea de bandÄ de la 802.11a âą IEEE 802.11nFuncÈioneazÄ pe benzile de frecvenÈÄ de 2.4 GHz sau 5 GHz. Rata aÈteptatÄ a datelor este cuprinsÄ Ăźntre 100 Mb/s Èi 600 Mb/s cu o distanÈÄ care poate ajunge pĂąnÄ la 70 metri. Este compatibil cu echipamentele 802.11a/b/g. âą IEEE 802.11acPoate funcÈiona simultan pe benzile de frecvenÈÄ 2.4 GHz Èi 5.5 GHz Èi asigurÄ rate de pĂąnÄ la 450 Mb/s Èi 1.3 Gb/s (1300 Mb/s). Este compatibil cu echipamentele 802.11a/b/g/n. âą IEEE 802.11adCunoscut Èi ca "WiGig". FoloseÈte o soluÈie Wi-Fi pe trei benzi folosind 2.4 GHz, 5 GHz Èi 60 GHz Èi oferÄ viteze teoretice de pĂąnÄ la 7 Gb/s. Figura evidenÈiazÄ cĂąteva din aceste diferenÈe.
Received: 26 November 2019 Revised: 10 January 2020 Accepted: 19 January 2020 DOI: 10.1111/obr.13005 PEDIATRICS/PHYSIOLOGY Adipokines: A gear shift in puberty DesirĂ©e Nieuwenhuis | NatĂ lia Pujol-Gualdo Amanda J. Kiliaan Department of Anatomy, Radboud university medical center, Donders Institute for Brain, Cognition and Behaviour, Preclinical Imaging Center PRIME, Nijmegen, The Netherlands Correspondence Amanda J. Kiliaan, PhD, Associate Professor, Department of Anatomy, Donders Institute for Brain, Cognition, and Behaviour, Preclinical Imaging Center PRIME, Radboud university medical center, 6500 HB Nijmegen, Geert Grooteplein 21N 6525 EZ Nijmegen, The Netherlands. Email: amanda.kiliaan@radboudumc.nl Funding information Europees Fonds voor Regionale Ontwikkeling (EFRO), Grant/Award Number: BriteN 2016 1 | INTRODUCTION The prevalence of obesity in adolescents and children is increasing in | Ilse A.C. Arnoldussen | Summary In this review, we discuss the role of adipokines in the onset of puberty in children with obesity during adrenarche and gonadarche and provide a clear and detailed overview of the biological processes of two major players, leptin and adiponectin. Adipokines, especially leptin and adiponectin, seem to induce an early onset of puberty in girls and boys with obesity by affecting the hypothalamic-pituitary- gonadal (HPG) axis. Moreover, adipokines and their receptors are expressed in the gonads, suggesting a role in sexual maturation and reproduction. All in all, adipokines may be a clue in understanding mechanisms underlying the onset of puberty in child- hood obesity and puberty onset variability. KEYWORDS adipokines, obesity, puberty 1,2 the age of 5 years were overweight or were with obesity in 2016, and 3 Obesity is defined by an excessive accumulation of white adipose tissue (WAT), and it is often indicated by a body mass index (BMI) 4 above 30. Two main types of adipose tissue were described: WAT and brown adipose tissue (BAT), which differ in morphology and func- 5-7 Ilse A.C. Arnoldussen and Amanda J. Kiliaan contributed equally to this work. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2020 The Authors. Obesity Reviews published by John Wiley & Sons Ltd on behalf of World Obesity Federation Obesity Reviews. 2020;21:e13005. wileyonlinelibrary.com/journal/obr 1 of 10 https://doi.org/10.1111/obr.13005 alarming rates. Specifically, worldwide, 41 million children below this number is expected to increase to 70 million in 2025. obesity is associated with various severe health complications, includ- ing increased risk of diabetes mellitus type 2, hypertension, heart dis- eases, and disturbances in sex hormone levels. 5,6 and mitochondria and plays a role in thermogenesis. Adipocytes in tion. BAT consists of adipocytes containing multiple lipid droplets WAT contain only a few mitochondria and a single lipid droplet. Adipose tissue has several functions including the storage of energy, thermogenesis, and the production and secretion of adipokines Generally, two physiological processes, adrenarche and gonadarche, 11,24 Childhood 5,7,8 a key role in puberty onset. Puberty is known as a period through which the body changes physically, being a physiological process resulting in the maturation of children, i.e. they develop sexual characteristics and obtain reproduc- 9,11 Adipokines are involved in a number of physiological processes including blood pressure, metabo- lism, glucose, and vascular homeostasis and may play amongst others 8-10 (hormones, cytokines, and peptides). tive functions. between obesity and puberty,2,12-23 the biological mechanisms under- lying obesity and puberty onset remain unclear. Hereafter, we review in detail the role of adipokines in the onset of puberty in childhood obesity. Although many studies have shown associations 2 | INITIATION OF PUBERTY PHYSIOLOGICAL PROCESSES IN THE interact to regulate the onset of puberty. During adrenarche, the adrenal cortex secretes steroid hormones (including 2 of 10 NIEUWENHUIS ET AL. androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate (DHEAS), androstenedione, and cortisol), insulin-like growth factor, and growth hormone, which contribute to the pubertal insights on new genetic loci (e.g. melanocortin-4 receptor, mitochon- drial carrier 2, and mitogen-activated protein kinase 13) and on sev- eral pathways that regulate the timing of puberty; however, it partly 34 9,24,25 Both adrenarche and gonadarche are involved in the development growth spurt, body odor, skin oiliness, and skeletal maturation. explains puberty timing variation. Thereby, defining the role of 25 adipokines is of importance in elucidating the variability in puberty as the expression of adipokines is sex-specific and is altered with body composition, adiposity, and during growth spurts. Moreover, adipokines and their receptors are expressed in gonads and several brain regions suggesting involvement in the onset of puberty and sex- ual maturation. Lastly, adipokines interfere in processes regulating timing and duration of puberty, for instance in the HPA and HPG axes which are both key players during adrenarche and gonadarche. Involvement of adipokines in the onset of puberty and specifically in individuals with obesity will be further reviewed in the next 2,24 3 | Puberty onset in girls is assessed using different markers, such as thelarche (breast development), menarche (the start of of pubic hair. pituitary-gonadal (HPG) axis is activated,2,26 and several hormones have been identified to participate in the activation of the HPG axis During gonadarche (Figure 1), the hypothalamic- 2,27 Kisspeptin, neurokinin B, and dynorphin are released by specialized including kisspeptin, neurokinin B, dynorphin, leptin, and ghrelin. 28 key regulator of the pulsatile secretion of gonadotropin releasing neurons, the KNDy neurons in the hypothalamus. Kisspeptin is a 29,30 B stimulates, and dynorphin inhibits the release of kisspeptin, which hormone (GnRH) from the hypothalamus. In addition, neurokinin implies that both coordinate a pulsatile release of kisspeptin. 31 Sub- sections. sequently, the activated HPG axis induces the pituitary gland to secrete luteinising hormone (LH) and follicle stimulating hormone (FSH). As a result, gametogenesis occurs, and the gonads will release sex hormones. Consequently, secondary sex characteristics develop including breast development in girls and an increased testicular vol- 2,26,32 is possibly due to differences in levels of body fat, hypothalamic-pitui- THE ONSET OF PUBERTY IN GIRLS ume in boys. The age at puberty onset varies greatly among individuals, which 19 35 menstruation), and pubic hair development. 33 genome-wide association studies have provided important new tary-adrenal (HPA) axis activity, and genetic background. Recent The average age of However, this age differs between cultures and ethnicities, and since 1980, age at menarche is girls at start of menarche is 12.4 years. 36 significantly decreasing. 36-39 F I G U R E 1 Hormonal regulation in the initiation of puberty in boys and girls. The secretion of kisspeptin, neurokinin B, and dynorphin from KNDy neurons initiate the release of gonadotropin releasing hormone (GnRH) from the hypothalamus. This activates the pituitary gland to produce and secrete luteinising hormone (LH) and follicle stimulating hormone (FSH), which in turn stimulate the gonads to produce estrogen and testosterone in girls and boys, respectively 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License NIEUWENHUIS ET AL. 3 of 10 T A B L E 1 Summary of included studies Authors Year Country Study Design Primary Outcome Sex Sample Size (n) Age (y) Data Collection Lian et al21 2019 China Cross-sectional Puberty starts earlier in Chinese Han girls with obesity compared with Chinese Han girls with normal weight. Girls 2996 9-19 2012 and 2013 Biro et al12 Lazzeri et al20 2018 USA 2018 Italy Longitudinal Cross-sectional Body mass index had a greater effect on age at menarche than did race and ethnicity. Girls 946 6-16 2004-2014 Li et al23 2018 China Longitudinal For both, boys and girls, a higher BMI (ie, overweight and obese) is associated with earlier onset of puberty Girls Girls Boys Girls 542 Deng et al22 Flom et al15 2017 China Cross-sectional Increased BMI is associated with early timing spermarche and menarche. Boys Girls Girls 1278258 9-15 2005-2012 He et al24 Holmgren et al17 2017 China 2017 Sweden Cross-sectional Longitudinal Onset of puberty is not related to obesity in boys. Boys Boys Girls Girls 782 7-17 972 929 5839 Kelly et al19 2017 UK 2016 Brazil 2016 USA Longitudinal prospective cohort Higher BMI in girls is associated with the onset of menstruation at an earlier age. 11 10-18 11-17 Barcellos Gemelli et al25 Cross-sectional Longitudinal Excess weight is associated with early age of menarche. Girls 727 2014 2003-2009 Glass et al16 Lee et al26 In girls, but not in boys, greater adiposity is associated with the earlier onset of puberty. Boys Girls 135 Cabrera et al27 Leonibus et al14 2014 USA 2013 Italy Cross-sectional Longitudinal Thelarche occurred earlier than recently reported, while age of menarche remained unchanged. Girls 610 3-17.9 2007 2005-2012 Currie et al13 2012 Europe, USA, Canada Cross-sectional Overweight/obesity during childhood predicts the early onset of puberty in girls. Girls 20410 11, 13, 15 2005-2006 2017 USA Prospective birth cohort Overweight/obese status at the age of 7 ye was associated with increased risk of early menarche 788 From birth to menarche occurred Pregnancies 1959-1966 2016 USA Cross-sectional Boys with overweight enter puberty earlier compared with boys with normal weight or obesity, while puberty starts later in boys with obesity compared with boys with normal weight and overweight. Boys 3872 6-16 2005-2010 Overweight during childhood shows a relation with the early onset of puberty in girls. 6535 4259 695 11 15 5.8-12.2 2009/2010 2013/2014 2014-2017 Higher BMI during childhood is associated with early puberty. 2008 and 2009 2000-2002 Obesity during childhood is related to the earlier onset of puberty. Boys Girls 84 123 71 (Continues) 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 4 of 10 NIEUWENHUIS ET AL. 3.1 | Fat storage For the initiation of puberty, the timing of stimulation and/or inhibi- tion of different hormones is important, and additionally, a certain amount and distribution of body fat is needed in order to start menar- che, which emphasizes the importance of body fat. From an evolution- ary point of view, body fat increases in mammalian females during puberty onset, and it highlights the need to guarantee a healthy preg- 40 women with anorexia nervosa. particularly body fat localized predominantly on the gluteofemoral fat depots, is profoundly associated with start of menarche, more than nancy, offspring, and maternal survival. fat, sex-hormones, and neuroendocrine alterations can evolve in men- strual dysfunction, for instance, in women with severe obesity or in 41-43 44-46 to gluteofemoral fat depots suggesting that leptin may convey infor- amount of total body fat. mation on body fat distribution to the hypothalamus during puberty. An improper level of body Importantly, body fat distribution, Blood leptin levels are strongly related 45 3.2 | HPG axis The HPG axis is activated by the release of kisspeptin resulting in the release of GnRH from the hypothalamus, and LH and FSH from the pituitary gland. In girls, FSH is involved in the development of the folli- cles in the ovaries, and it promotes the secretion of estrogen. LH stim- ulates the production of androgen hormones and induces ovulation 48 9,47 the release of kisspeptin and neurokinin B, and kisspeptin thereby (Figure 1). The secretion of estrogen has an inhibitory effect on inhibits the GnRH release from the hypothalamus. pattern of GnRH is important for the regulation of the menstrual cycle. This roughly 28-day-cycle comprises several phases, including the follicular phase and luteal phase. During the follicular phase, increasing levels of FSH stimulate the maturation of follicles and the production of estrogen from the ovaries. This in turn inhibits the release of FSH from the pituitary gland. A high level of estrogen will induce the production of LH by the pituitary gland, resulting in ovula- tion. The matured follicle secretes progesterone thereby inhibiting the release of GnRH. When the corpus luteum is demolished, there is less 48 3.3 | Adipokines According to results from studies reported in Table 1, girls with obe- sity enter puberty earlier compared with girls with normal higher leptin concentrations inhibit the intake of food and increases inhibition of GnRH. As a consequence, the cycle will start again. whole process, starting from the activated HPG axis, results in the development of the secondary sex characteristics in girls including 9,47 thelarche and menarche. 13,14,16-23,49-51 weight. these girls might be found in the secretion of adipokines. For instance, leptin is positively associated with the amount of body fat. Generally, energy expenditure. 9,52-54 An explanation for the early onset of puberty in The expression This TABLE 1 (Continued) Authors Year Country Study Design Primary Outcome Sample Sex Size (n) Age (y) Data Collection Herman-Giddens et al28 2012 USA Cross-sectional Observed mean ages of beginning genital and pubic hair growth and early testicular volumes were earlier than in past studies, depending on the characteristic and race/ethnicity. Boys 4131 6-16 2005-2010 Sorensen et al29 Aksglaede et al30 2010 2009 Denmark Denmark Cross-sectional/longitudinal Longitudinal Puberty onset at earlier ages was associated with an increased BMI in boys. Boys 1528 5.8-19.9 1991-1993/2006-2008 1930-1969 Juul et al31 Ribeiro et al32 2007 2006 Denmark Portugal Retrospective cohort Cross-sectional Higher BMI is associated with early voice break. 11-15 10-15 1990-1999 Kaplowitz et al18 Abbreviation: BMI, body mass USA Cross-sectional The early onset of puberty in Caucasian girls is likely related to an increased BMI. 5-12 1992-1993 2001 index. The higher BMI in boys and girls at 7 y of age, the earlier they enter puberty. Boys 21 612 Girls 135 223 Boys 463 Boys 382 Girls 437 Girls 10 750 Early sexual maturation in boys and girls is associated with overweight. 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License NIEUWENHUIS ET AL. 5 of 10 Leptin may possibly play a role in adrenarche as its plasma level increases with higher levels of body fat and as it can modulate both girls. 33 ing adrenarche. In coherence, in children with obesity, the androgen These findings suggested that lower reproductive status was associated with higher total adiponectin concentrations and that a higher reproductive status was related to higher HMW adiponectin the HPA and HPG axes. These axes are functionally integrated dur- DHEAS was positively associated with leptin levels. Nevertheless, concentrations in girls. In addition, individuals with obesity often another study showed that enhanced adrenal androgen secretion in girls with premature adrenarche was not explained by leptin or BMI 55 ated with androgen levels in girls ; however, it was not related to levels. and IL-6. TNF-α alters, and IL-6 inhibits the expression of 56 8 In addition, the adipokine adiponectin was negatively associ- 57 differences of adiponectin seem to develop during the progression of 56 adiponectin (Figure 2). Thereby, a low level of total adiponectin and/or high levels of inflammatory cytokines in individuals with obe- sity can promote the onset of puberty. Many more adipokines are secreted by WAT including omentin, 52,65-67 9,36,62,68 adrenarche in girls with Prader-Willi syndrome. Interestingly, sex puberty. adrenarche; however, both are not required factors. Thus, leptin and adiponectin might be able to influence In gonadarche, leptin can stimulate the secretion of kisspeptin, and subsequently activation of the HPG axis, which eventually increases the expression of estrogen and androstenedione in the ova- 58 2,60 65-67 The expression of these ries (Figure 2). Ob gene in WAT, resulting in the synthesis and secretion of leptin. Thus, high levels of leptin promote onset of puberty in girls via secre- tion of kisspeptin, and estrogen stimulates leptin secretion addition- ally. Moreover, adiponectin can affect the HPG axis due to the expression of adiponectin receptors in the hypothalamus, pituitary In return, estrogen stimulates the expression of the 59 gland, and gonads. onset as it inhibits the secretion of kisspeptin and GnRH in the hypo- thalamus and the release of GH and LH in the pituitary gland, and 2,60-62 52,60 63 girls with central precocious puberty (CPP). Moreover, total adiponectin had negative correlations with progression of puberty in girls (defined by Tanner stages), whereas HMW adiponectin had FIGURE 2 Adipokinesaffectingthe initiation of puberty in girls. Leptin stimulates the release of kisspeptin in KNDy neurons, which activates the hypothalamus to produce gonadotropin releasing hormone (GnRH). In response to the release of GnRH, the pituitary gland secretes follicle stimulating hormone (FSH) and luteinising hormone (LH), which stimulates the ovaries to release estrogen resulting in the formation of secondary sex characteristics in girls. Estrogen stimulates the production of leptin. Adiponectin inhibits GnRH release resulting in reduced levels of GnRH and thereby a delayed onset of puberty. TNF- α and IL-6 inhibit the production of adiponectin and therefore stimulate the onset of puberty In detail, adiponectin is a regulator of puberty thereby inhibiting the onset of puberty (Figure 2). with obesity often have low levels of adiponectin. et al. showed that total adiponectin was significantly lower, whereas high molecular weight (HMW) adiponectin was significantly higher in ment. 55 63 develop a chronic low-grade inflammatory state, which can be indi- cated by a high level of circulating inflammatory cytokines like TNF-α 64 Individuals Sitticharoon positive associations with LH levels and the progression of puberty in 63 visfatin, resistin, and chemerin. and visfatin are expressed in the ovaries. adipokines in the ovaries suggests a role within the reproductive sys- tem; however, the exact biological processes have to be examined. Thus, specifically leptin, adiponectin, and inflammatory cytokines pro- duced by WAT could be permissive key players during an early onset of puberty in girls with obesity. As an exception, HMW adiponectin seems to have a stimulatory effect on peripheral repro- ductive function as HMW is not able to cross the blood brain 63 barrier. 4 | Markers that are used to assess puberty onset in boys are THE ONSET OF PUBERTY IN BOYS spermarche, voice break, testicular volume, and pubic hair develop- 35 spermarche develop in the early stages of puberty onset, voice In women, omentin, chemerin, While pubic hair development, larger testicular volume, and 69 testicular volume increases, which occurs at an average age of break usually appears in later stages of puberty. Generally, first 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 6 of 10 NIEUWENHUIS ET AL. 11.9 years, followed by the development of pubic hair at 12.2 years of average, and lastly, boys experience spermarche around an aver- 55 related with leptin levels. Thereby, leptin plausibly has a minor impact in adrenarche in boys. Since leptin receptors are found in the hypothalamus, pituitary gland, and testes, they might be involved in the onset of puberty by affecting the HPG axis during gonadarche. Leptin stimulates the release of kisspeptin and GnRH, and as a consequence, it accelerates the onset of puberty (Table 1, Figure 3). In contrast, adiponectin inhibits the secretion of GnRH, GH, LH, and FSH therewith delaying the onset of puberty. However, adiponectin levels are generally lower in men compared with women and even lower in men with obe- age age of 13.4 years. 70 4.1 | Fat storage Many aspects of the reproductive physiology are energetically demanding,71 and therefore, an adequate energy level is necessary. In boys, a dynamic change in body composition occurs around the age of 10 to 13 years, in which they gain approximately 40% of sity. culating inflammatory cytokines. levels can stimulate the HPG axis and therewith an early onset of puberty in boys. Nevertheless, leptin can inhibit the production of tes- 72 mostly consisting of lean mass, which causes exhaustion of most of fat. Subsequently, a growth spurt follows in which they gain tissue 72 in boys, an adequate amount of body fat is important in the onset of their body fat. These alterations in amount of body fat indicate that 4.2 | Puberty in boys is initiated by the release of kisspeptin. As mentioned before, this activates the HPG axis, resulting in the release of GnRH from the hypothalamus, and consequently the release of LH and FSH 9,74 puberty. tosterone from the testes, to estrogen (Figure 3). of the development of secondary sex characteristics in boys. Additionally, leptin can affect fertility in men as it can modulate the nutritional support of spermatogenesis, and moreover, dysfunction of spermatogenesis is associated with an increased leptin level and 73 58 2,60-62 HPG axis from the pituitary gland (Figure 1). and LH stimulates the secretion of testosterone from the testes, which inhibits the release of kisspeptin from the KNDy neurons and 9,48 in men, the release of kisspeptin is more consistent, causing a con- 29,48 subsequently GnRH from the hypothalamus. receptors expressed on KNDy neurons. In humans, KNDy neurons Contrarily to women, LH-induced testosterone levels lead to the stant release of LH. development of secondary sex characteristics in boys. differences between sexes in kisspeptin release are related to a sex- specific and sex steroid-dependent kisspeptin system as estrogen and progesterone modulate kisspeptin activity through the sex-steroid 48 in the infundibular nucleus are involved in negative and positive sex- 48 tal exposure to sex steroids and result in sex-specific differences in steroid feedbacks. kisspeptin release. These sexual dimorphisms are induced by perina- 75,76 4.3 | Adipokines The association between obesity and puberty onset in boys is rather controversial compared with findings in girls. Most studies reported an early onset of puberty in boys associated with increased ate adipose tissue from actual breast tissue. stages are more difficult to assess than female stages as boys lack a more determined marker such as menarche. Thirdly, puberty onset can be indicated by the activation of the HPG axis, and the presence of these secondary sex characteristics is the result of hormonal 2 14,17,22,23,50,51,77,78 BMI, 20,49 all while others reported no associations at Current markers used 79 16,80 or a delayed onset of puberty (Table 1). The presence of excessive adipose tissue can be involved in puberty onset in boys as the secretion of adipokines can modulate both adrenarche and gonadarche. Leptin can affect adrenarche by modulating both the HPG and HPA axes,33 and moreover, androgen levels were positively 55 nal androgen secretion in boys with premature adrenarche was not associated with plasma leptin levels. Nevertheless, enhanced adre- 9 In more detail, 61,62 adiponectin, and individuals with obesity often have high levels of cir- Moreover, inflammatory cytokines, TNF-α, and IL-6, inhibit expression of the leptin receptor in the testis. FSH induces spermatogenesis, too. function and role still have to be examined. 64 High leptin and low adiponectin and fat tissue can convert testosterone Both processes might result in the delay 29,61,79 81,82 In men, other adipokines like chemerin are found in the gonads 65 Thus, particularly high leptin and low adiponectin levels stimulate the HPG axis and thereby accelerate the onset of puberty in boys. Additionally, leptin can dysregulate the development of secondary sex characteristics and spermatogenesis by affecting testosterone levels and nutritional sup- port of spermatogenesis. 5 | LIMITATIONS AND FUTURE RESEARCH DIRECTIONS Even though multiple epidemiological studies have shown the link between puberty onset and obesity, there are some important limita- tions. Firstly, determining both the onset and stage of puberty is rather difficult. For instance, assessing the stage of breast develop- ment in girls with obesity is complicated as clinicians should differenti- 2 changes in response to the activated HPG axis. to determine the onset of puberty refer to secondary sex characteris- tics, such as testicular volume in boys and breast development in girls. A more accurate measurement of puberty onset would be to combine secondary sex characteristics with plasma or serum hormone level measurements such as LH, FSH, adipokines, e.g. leptin. Thereby, differences in puberty measurements could explain variations in the age of puberty onset between boys and girls within different Thereby, resistin is expressed in the testes of rats, but its exact 83 Secondly, male pubertal 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License NIEUWENHUIS ET AL. 7 of 10 FIGURE 3 Adipokines affecting the initiation of puberty in boys. Leptin activates kisspeptin secretion in KNDy neurons, this activates the production of gonadotropin releasing hormone (GnRH) from the hypothalamus. GnRH stimulates the pituitary gland to secrete follicle stimulating hormone (FSH) and luteinising hormone (LH), activating the production of testosterone from the testes allowing the development of secondary sex characteristics. Leptin also inhibits the production of testosterone, which may cause a delayed onset of puberty. Adiponectin inhibits GnRH release. Low levels of adiponectin, as a result of TNF-α and IL-6 expression, lead to a reduced inhibition of GnRH. In response to GnRH release, the pituitary gland will secrete FSH and LH, and the testes will produce testosterone resulting in the development of secondary sex characteristics in boys countries, and In addition, the inclusion of a of puberty. ferent time points is complicated, as subjects examined several decades ago presented pronounced differences concerning lifestyle patterns such as nutrition and exercise habits. Lastly, obesity or over- weight is often determined by BMI, a classification based on weight and height measurements. Additionally, it is important that all studies studies or across continents, ethnicities proper age range (8-16 years) is important when assessing the onset (Figure 4). 12-15,17,20-23,49,77-79,84,85 30,47 Furthermore, comparison between studies from dif- 86 Specifically in children, BMI is often dependent on age and growth use the same anthropometric standards and sex-specific cut-offs. 13,14,16-23,49-51,77-80 fat and would represent a more accurate measurement in its regard. Based on this review, several suggestions can be made for further research. Firstly, the roles of adipokines like resistin, chemerin, visfatin, and omentin in puberty onset, fertility, and sexual maturation should be examined in detail. Secondly, future research examining the onset of puberty should combine indicators of puberty onset (e.g. breast development or testicular volume) with plasma or serum hor- mone measurements such as LH, FSH, sex-steroids, adipokines (e.g. spurts. ment in case of growth spurts. distribution of body fat should be taken into account in determining puberty and obesity in children. For instance, the body adiposity index (BAI), which was introduced in 2011 by Bergman et al.,87 uses hip cir- cumference and height in order to estimate the percentage of body 87 Thereby, BMI is a less accurate measure- F I G U R E 4 87,88 Therefore, both percentage and Average age of puberty onset in Europe, China, and the United States according to several studies from Table 1. Age of puberty onset ranges from 8.47 to 13.33 years in girls and from 8.63 leptin), and body fat distribution (e.g. BAI,87 waist-hip ratio's and/or dual-energy X-ray absorptiometry (DXA)2). Additionally, defining con- sistent and general measurements of puberty in both boys and girls, combined with a proper age range (8-16 years), would facilitate the comparisons between different studies and their results. 12-15, 17, 20-23, 25-29, 31 to 13.7 years in boys. included if average age of markers used to assess puberty was not reported. Pink: girls. Blue: boys Studies (Table 1) were not 39, 56 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 8 of 10 NIEUWENHUIS ET AL. 6 | CONCLUSION In conclusion, epidemiological data regarding obesity and puberty onset in girls show similar outcomes as adiposity results in the early onset of puberty in girls. The majority of the studies examining boys with obesity indicate an early onset of puberty, while not all reported an earlier onset of puberty. In detail, high leptin, TNF-α, and IL-6 levels combined with low adiponectin levels stimulate the activation of the HPG axis in girls and boys with obesity, and 5, 45, 50, 51 REFERENCES 1. Kumar S, Kelly AS. Review of childhood obesity: from epidemiology, etiology, and comorbidities to clinical assessment and treatment. May- o Clin Proc. 2017;92(2):251-265. 2. Reinehr T, Roth CL. Is there a causal relationship between obesity and puberty? The Lancet Child & adolescent health. 2019;3(1):44-54. 3. WorldHealthOrganization. Facts and figures on childhood obesity. 2017. 4. Guglielmi V, Sbraccia P. Obesity phenotypes: depot-differences in adipose tissue and their clinical implications. Eat Weight Disord. 2018; 23(1):3-14. 5. Gomez-Hernandez A, Beneit N, Diaz-Castroverde S. Escribano O. 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FUNDING INFORMATION This research was funded by Europees Fonds voor Regionale Ontwikkeling (EFRO), project BriteN 2016. ORCID Ilse A.C. Arnoldussen Amanda J. Kiliaan https://orcid.org/0000-0002-7395-5284 https://orcid.org/0000-0002-2158-6210 13, 14, 16-26, 29-32 Furthermore, several receptors Nevertheless, We conclude Search strategy We searched PubMed for articles published before Novem- ber 15th, 2019 using relevant keywords, including âonset of puberty and adiposity/obesityâ, âonset of pubertyâ, âchildren with obesityâ, âadipose tissueâ, âchildhood obesityâ, âadiposityâ, âobesityâ, âadipokine(s)â, âHPG axisâ, âadipokines ovary/ova- riesâ, or âadipokines testesâ, either alone or in combination. 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Management and Globalization Global Management Why companies go global How companies for global Global Business environments Global Business Types of global business Pros and cons of global businesses Ethnic Challenges for global business Culture and Global Diversity Cultural intelligence Silent language of culture Tight and loose cultures Values and national cultures Global Management Learning Are management theories universal? Intercultural competencies Global learning goals Key concepts of the challenges of globalisation: Global economy Resources, markets and competition are worldwide in scope Internationalisation The process of increasing involvement in international operations Globalization/Deglobalization Glob- the growing interdependence among elements in the global economy The worldwide interdependence of resource flows, product markets and business competition World 3.0 Different views: World flat vs. round Distance is a metaphor that represents the degree of dissimilarities between countries Balancing cooperation in the global Global Management Global management - managing things in different countries Managing business and organizations with interests in more than one country What do we expect from global Managers Knowing how to adapt Knowing the language Global Manager Is culturally aware and informed on international affairs International Business Conducting for-profit transactions of goods and services across national boundaries International Motive Why do firms internatioalize their activities Cheaper labour Labour tax Natural resources Enrolments to do business Clientele Exclusive materials Personal benefits: Taxes Reasons why businesses go global Customers Suppluers Capital During (1993) - 4 motive 1. Market seeking 2. Efficiency Seeking 3. Resource seeking 4. Strategic Asset Seeking Cuervo Cazurra, Narula and un (2015) - 4 motive s Internationalization Motives A company may also explore the opportunities in different markets in order to take advantage and in some cases extend the product life cycle What is a Market Entry Strategy Involves the sale of goods or services to foreign markets but do not require expensive investments Franchising Exporting and importing Involve the sale of goods or services to foreign markets but do Types of market entry strategies Global sourcing Exporting Importing Licensing agreement Franchising Types of Foreign Direct Investment (FDI) strategies: Joint venture Strategic alliance Owned Subsidiary (sometimes called WOS) How to go abroad What conditions will affect the decisions of firms on how to internationalize their activities? During (1978)- Eclectic paradigm OLI model OLI- Ownership, Location and Internalization Advantages Ownership advantages Resources owned by the organization that can be transferred across locations include trademarks, production techniques and processes, managerial skills and other resources not available to the competitors Location Advantages Represent the implications of choosing to produce or to perform activities in a specific location (country or region) Internalization Advantages: The ability to internalize or to incorporate activities that add value to its business Evolution of Concepts- New Elements Although economic factors are certainly important to explain the formation, growth and expansion of firms within and across national borders, they are not sufficient to explain the additional complexity when a firm decides to expand its activities across national borders Economic factors Investigate the economic elements that affect the internationalization of firms Behavioural Elements Explaining the additional challenges (and perhaps opportunities) a firm faces in foreign host countries when compared to indigenous (local) firms Behavioural theories Johanson and Wiedersheim-Paul (1975) and Johanson and Vahlne (1977) Included the psychic Distance concept (beckerman,1956) to explain the internationalization behaviour of firms The Uppsala internationalization model Psychic distance is: the sum of factors preventing the flow of infomatio from and to the market Psychic Distance is a broad concept that includes several elements such as: language, culture, political systems, level of education, level of industrial development Firms behave in a âRisk Averseâ manner It means that when the perceived risk goes down, the firm increase its commitment to the foreign market \ The Haier Group Data Strategy Big DATA and Small DATA The use of small data to satisfy individual customersâ needs, however, the book mentions a huge cultural shock at the plant in Camden, south caroline Ex: top down, hard hat colors and hierarchy Culutral Differnces can have a huge impact on the internationalization of firms Kogut and Singh (1988)- Cultural Distance Index First statsical study on the implication of ciltiral distance to the selection of entry mode When investigating in culturally distant countries, foreign firms can choose to partner with foreign firms in order to gain local knowledge and share the risk associated to the investment (higher commitment = higher risk) How Companies Go Global Global sourcing The process of purchasing materials or services around teh world for local use Exporting Selling locally made products in foreign markets Importing Buying foreign made products and selling them domestically Exports correspond to what percentage of Candain GDP What countries are the major trending partners of Canada Management and Globalization How Companies Go Global Licensing Agreement One firm pays a fee for rights to make or sell another companyâs products What are the potential risks associated to licesning The case of new balance in China Franchising A fee is paid for the rights to use another firms name, branding and methods Insourcing Insourcing: refers to local job creation that results from foreign direct investment Types of insourcing Joint ventures: operate in a foreign country through co-ownership by foreign and local partners Strategic alliances: A partnership in which foreign and domestic firms share resources and knowledge for mutual gains Foreign subsidiaries: local operation completely owned by a foreign firm Criteria for choosing a joint venture partner: Familiarity with your firmâs major business String local workforce Values its customers Future expansion possibilities Strong local market for partnerâs own products Good Profit potential Sound financial standing Global business environments Legal and poliical systems Trade agreements and trade barriers Regional economic alliances Legal and political systems Differing laws and practices regards Business ownership Negotiation and implementation of contracts Foreign currency exchange Protection of intellectual property rights Counterfeit merchandise Political risk Potential loss in value of foreign investment due to instability and political changes in the host country Political risk analysis (expertise/experience) Forecast political disruptions that threaten the value of a foreign investment Changes in the rules of the game Brexit US Trade Wars-mexico-China Other examples Bolivia, Venezuela, China De-globalization The process of weakening interdependence among nations Trade Agreements and trade Barriers World trade organization Most favourd nation status Tariffs Nontariss barriers (quotes, restrictions, etc.) Protectionism Regional Economic Alliances USMCA (replacment for the NAFTA-North American Free trade Agreement) EU- European Union APEC- Aisa Pacific Economic Copperation ASEAN - Association of Southeast Asian Nationas SADC - Southern Africa Development Community MERCOSUR- Chapter 5- Global Management and Cultural Diversity (part 2) Review Types of global business Global corporation MNE (multinational enterprise) or MNC (multinational corporation) with extensive business operations in more than one foreign country Transnational corporation A global corporation that operates worldwide on borderless basis Some host country complaints about MNCs Host Country companits about MNCs: Excessive profits Interference with local government Domination of local economy Interference with local government Hiring the best local talent Limited technology transfer Disrespect for local customers Examples - War in Ukraine Disruption in global -value chains and increased pressure and interference of MNCs with local government Fertilizer imports in Brazil (one of the major producers of agricultural commodities) We must consider the triple bottom line and the impact in society, the environment and the economy $2.5 billion invest in potash mine in Brazill What about Globalization gap Large multinationals adn industrilizednaitons gaining disporoportinonally form globalization Globalization gap: Large multinational and industrialized nations gaining disproportionally from Globalization Some MNC complaints about host countries MNC Complaints about host countries: Profiit limitations Laws and regulations Overpirce resources Exploitative rules Foreign exchange restriction Failure to uphold contracts Mutual benefits for host countries and multinational companies Mutual benefits for host country and global corporation of MNC: Shared growth opportunities Shared income opportunities Shared learning opportunities Share development opportunities Develop projects together What are some of the ethical challenges for global business Ethincal challenges for global business Child labour Employmnet of children for worl otherwise done by adults Sweatshops Employment of workers at very low wages for long hours in poor working conditions Ex: Nike bad labour prices Unsafe working conditions Corruption Illegal practices that further oneâs business interests Corrupiotn of froeign public officials Act makes it illegal for Candain firms and their representatives to engage in corrupt practices overseas Bribes to foreign officials Excessive commissions Non-monetary gifts Sweatshops Conflict materials What is culture Culture : The shared set of beliefs, values, and patterns of behvaiourr common to a group of people Food preferences Values and traditions Language and beliefs Religion Art music Life style Hofstede defines culture as: âThe collectiv programing of teh mind distinguishing the members of one group or category of people from othersâ What is culture shock Culture Shock: Confusion and discoumfert a person experiences in an unfaamiliar culture Stages to adjusting to a new culture Confusion Small vitorires The honeymoon Irritation and anger Reality Cultural Intelligence The ability to adapt and adjust to new cultures What is Ethnocentrism Tendency to consider oneâs own culture as superior others Slinet languages of culture Contect Low context High context Space Proxemics Ex: personal space Time Monochronic Polychronic High and low contexts cultures Edward T.Hall (1959) Def: Part of a discourse that surround a word or passage and can throw on its meaning Low context cultures Emphizes communication via spoken or written words Countries like United States, Canada and Germany High context cultures Rely on nonverbal and situational cues as well as on spoken or written works Thailand Malaysia Time Monochronic cultures People tend to do one thing at a time Canda Polychronic cultures Time is used to accomplish many different things at once Egypt Space Proxemics Study of how people use space to communicate In North American people value âpersonal spaceâ Many Latin and Asian cultures expect much less personal space Tight and Loose Cultures Cultural tightness-looseness Tight = Strength of norms that govern social behvaviour Japan, Korea, Malaysia Loose = tolerance for any deviation from norms Australia, Brazil, Hungary Values and national cultures (Hofstede) Power distance Uncertainty avoidance Individalism-collectivism Masculinity-femininty Time Orientation Indulgence vs. Restraint Comparative management How management pratices systematically differ among countries and /or cultures Intercultural competencies Skills and personal characteristics that help us be successful in cross cultural situations Global Managers (know how to adapt) Need to successfully apply management functions across interantional boundaries Global Learning goals Not universal Engage critical thinking Look everywhere for new management ideas Always consider culture
I. DĂ©finition L'appel d'offres est donc une procĂ©dure par laquelle un acheteur public choisit l'offre Ă©conomiquement la plus avantageuse, sans nĂ©gociation, sur la base de critĂšres objectifs prĂ©alablement dĂ©finis Son but est de mettre en concurrence plusieurs entreprises privĂ©es pour obtenir la meilleure offre possible. Les caractĂ©ristiques principales sont les suivantes : âą Absence de nĂ©gociation : L'acheteur sĂ©lectionne l'offre uniquement sur la base des propositions reçues, sans nĂ©gociation avec les candidats âą CritĂšres objectifs : La sĂ©lection se fait selon des critĂšres dĂ©finis Ă l'avance et communiquĂ©s aux candidats âą Transparence : Les appels d'offres publics sont soumis Ă des rĂšgles strictes de publicitĂ© et de transparence Ce principe dâappel dâoffre garantie donc lâĂ©galitĂ© de traitement des entreprises privĂ©es candidates et une certaine transparence. II. Les diffĂ©rentes formes dâappel dâoffres Il existe deux formes principales d'appels d'offres dans les marchĂ©s publics : âą Appel d'offres ouvert : Toute entreprise intĂ©ressĂ©e peut rĂ©pondre Ă lâappel dâoffre âą Appel d'offres restreint : Seuls les candidats prĂ©sĂ©lectionnĂ©s par l'acheteur sont autorisĂ©s Ă soumettre une offre. Cette procĂ©dure est particuliĂšrement adaptĂ©e aux marchĂ©s complexes ou spĂ©cialisĂ©s, oĂč l'acheteur souhaite prĂ©sĂ©lectionner les entreprises les plus qualifiĂ©es avant d'examiner leurs offres en dĂ©tail. III. Les objectifs pour une PME de prospecter des nouveaux marchĂ©s via les appels dâoffres Il y a plusieurs objectifs pour une entreprise de prospecter de nouveaux marchĂ©s : â trouver de nouveaux clients ; â garantir le dĂ©veloppement de lâactivitĂ© de lâentreprise ; â compenser lâĂ©rosion du portefeuille clients existant ou remplacer les clients peu ou pas rentables Ainsi, au-delĂ du simple gain commercial, les appels d'offres reprĂ©sentent un vĂ©ritable levier stratĂ©gique de dĂ©veloppement pour les entreprises, quelle que soit leur taille. IV. La procĂ©dure de rĂ©ponse aux appels dâoffre 1. Les Ă©tapes principales Voici les principales Ă©tapes pour rĂ©pondre efficacement Ă un appel d'offres : âą Identifiez les appels d'offres pertinents âą Activez des alertes automatiques sur les plateformes dĂ©diĂ©es âą TĂ©lĂ©chargez le Dossier de Consultation des Entreprises (DCE) âą Analysez minutieusement le cahier des charges et le rĂšglement de consultation âą PrĂ©parer la rĂ©ponse soit constituez le dossier de candidature avec les documents administratifs requis âą Transmettre la rĂ©ponse soit dĂ©poser le dossier complet sur la plateforme de dĂ©matĂ©rialisation avant la date limite âą Suivre la rĂ©ponse : en cas de rejet, demandez un retour pour identifier les points d'amĂ©lioration 2. La consultation des appels dâoffre Les PME doivent dâabord identifier les appels d'offres pertinents. Cela peut se faire par : âą Les rĂ©seaux professionnels : Participer Ă des salons, des confĂ©rences et des Ă©vĂ©nements rĂ©seaux aide Ă dĂ©couvrir des opportunitĂ©s. âą La veille : S'abonner Ă des bulletins d'information et des alertes sur les marchĂ©s pertinents. âą La consultation de plateformes en ligne : De nombreux sites web rĂ©pertorient les appels d'offres publics, utilisateur aux PME de filtre par secteur et localisation. Lâassistant(e) de gestion dispose de plusieurs sites de marchĂ© publics Voici les principaux sites français pour consulter les appels d'offres publics : Les Sites officiels : ïŒ BOAMP (Bulletin Officiel des Annonces des MarchĂ©s Publics) : C'est le site officiel qui publie les appels d'offres de l'Ătat, des collectivitĂ©s territoriales et des Ă©tablissements publics ïŒ PLACE (Plateforme des Achats de l'Ătat) : C'est la plateforme de dĂ©matĂ©rialisation des marchĂ©s publics de l'Ătat. La publication y est obligatoire pour les marchĂ©s de l'Ătat Ă partir de 40 000 ⏠HT ïŒ JOUE (Journal Officiel de l'Union EuropĂ©enne) : Il publie les appels d'offres europĂ©ens Les plateformes privĂ©es : ïŒ France MarchĂ©s : Ce portail agrĂšge les appels d'offres de plus de 300 journaux rĂ©gionaux, du BOAMP, du JOUE et de plus de 1000 sites d'acheteurs publics ïŒ MarchĂ©s Online : Cette plateforme donne accĂšs Ă l'ensemble des appels d'offres publiĂ©s, quel que soit le secteur d'activitĂ© ïŒ E-marchespublics : Ce site permet d'accĂ©der aux appels d'offres publiĂ©s sur diverses sources comme le BOAMP, le JOUE, la presse et les profils d'acheteurs Les Autres sources : ïŒ Journaux d'Annonces LĂ©gales (JAL) : Environ 540 journaux en France sont habilitĂ©s Ă publier des annonces lĂ©gales, dont les appels d'offres ïŒ Sites internet des administrations publiques : La plupart des administrations publient leurs appels d'offres directement sur leur site internet ïŒ Presse spĂ©cialisĂ©e : Certaines revues sont spĂ©cialisĂ©es dans les appels d'offres de leur dĂ©partement ou rĂ©gion Pour une veille efficace, il est recommandĂ© d'utiliser des outils de veille Ă©lectronique ou de s'abonner aux alertes proposĂ©es par ces diffĂ©rentes plateformes. Cela permet de recevoir automatiquement les appels d'offres correspondant Ă vos critĂšres de recherche 3. Les candidatures dâappels dâoffre Pour concourir Ă un marchĂ© public, il est possible de se prĂ©senter seul, de prĂ©senter une candidature groupĂ©e avec plusieurs entreprises : âą La candidature seule : l'entreprise se prĂ©sente pour exĂ©cuter personnellement le marchĂ©. Elle a la capacitĂ© technique et financiĂšre dâexĂ©cuter seule et dans son entier le marchĂ©. âą Le groupement : le groupement conjoint (lâentreprise n'est responsable que de la part du marchĂ© qu'elle exĂ©cute) ou le groupement solidaire : (chaque membre du groupement est engagĂ© financiĂšrement pour la totalitĂ© du marchĂ©. Cela signifie que tous les membres sont collectivement responsables de l'exĂ©cution complĂšte du contrat). 4. La rĂ©ponse Ă lâappel dâoffre La rĂ©ponse Ă un appel d'offres doit contenir les Ă©lĂ©ments suivants : âą une lettre de prĂ©sentation : PrĂ©senter briĂšvement l'entreprise et son intĂ©rĂȘt pour le projet. âą une proposition technique : DĂ©tails sur la façon dont le projet sera rĂ©alisĂ© soient les mĂ©thodes et leurs chronologies. âą Une proposition financiĂšre : faire une estimation des coĂ»ts et des conditions de paiement Le dossier de rĂ©ponse Ă©tant lâinterface entre la PME et le donneur dâordre, il convient de lui apporter le plus grand soin. Il faut donc prĂ©parer le dossier de rĂ©ponse et remplir le document unique de marchĂ© europĂ©en appelĂ© DUME : dĂ©claration sur l'honneur standardisĂ©e et Ă©lectronique utilisĂ©e dans les procĂ©dures de marchĂ©s publics Le certificat Ă©lectronique est un Ă©lĂ©ment essentiel pour rĂ©pondre aux appels d'offres publics dĂ©matĂ©rialisĂ©s. Voici les principaux points Ă retenir : ïŒ Depuis le 1er octobre 2018, la dĂ©matĂ©rialisation est obligatoire pour les marchĂ©s publics supĂ©rieurs Ă 40 000 ⏠HT ïŒ Dans ce cadre, une signature Ă©lectronique valide est requise pour signer les documents de rĂ©ponse aux appels d'offres. L'utilisation d'un certificat Ă©lectronique pour les appels d'offres prĂ©sente plusieurs avantages : ïŒ Gain de temps dans les Ă©changes avec les acheteurs publics ïŒ Ăconomies sur les frais d'impression et d'envoi ïŒ SĂ©curisation accrue des documents transmis ïŒ PossibilitĂ© de signer Ă distance Les certificats Ă©lectroniques pour rĂ©pondre aux appels d'offres sont dĂ©livrĂ©s par des prestataires de services de confiance qualifiĂ©s, conformes au rĂšglement europĂ©en eIDAS et au RĂ©fĂ©rentiel GĂ©nĂ©ral de SĂ©curitĂ© (RGS) français. Les principaux Ă©metteurs de ces certificats sont : ïŒ CertEurope ïŒ ChamberSign France ïŒ Certigna (filiale de Docaposte) ïŒ Dhimyotis ïŒ Universign La date limite de rĂ©ception des offres (DLRO) est un Ă©lĂ©ment crucial dans le processus des appels d'offres pour les marchĂ©s publics. La DLRO, Ă©galement appelĂ©e date limite de remise des offres ou des plis, correspond Ă la date et l'heure limites auxquelles les candidatures ou offres doivent ĂȘtre reçues par l'acheteur public1 Le dĂ©lai commence le lendemain de la date d'envoi de l'avis d'appel Ă la concurrence par l'acheteur. Dans cette dĂ©marche, lâentreprise peut rĂ©aliser un tableau de suivi des appels dâoffres dont voici un exemple : 5. La rĂ©ponse Ă lâappel dâoffre Une fois la dĂ©cision prise, l'acheteur doit envoyer une notification officielle Ă l'entreprise retenue. Cette communication doit ĂȘtre faite par Ă©crit, gĂ©nĂ©ralement par lettre recommandĂ©e avec accusĂ© de rĂ©ception ou par voie Ă©lectronique sĂ©curisĂ©e. Tout candidat Ă©vincĂ© peut demander par Ă©crit des informations complĂ©mentaires sur les motifs du rejet de son offre. L'acheteur doit alors rĂ©pondre dans un dĂ©lai de 15 jours en fournissant : âą Les motifs dĂ©taillĂ©s du rejet de la candidature ou de l'offre âą Les caractĂ©ristiques et avantages de l'offre retenue âą Le nom de l'attributaire V. Le paiement des marchĂ©s en appel dâoffres Le dĂ©lai maximal de paiement est gĂ©nĂ©ralement de 30 jours. Ce dĂ©lai est portĂ© Ă 50 jours pour les hĂŽpitaux et 60 jours pour les entreprises publiques. . Le paiement intervient aprĂšs constatation du "service fait", c'est-Ă -dire une fois que la prestation a Ă©tĂ© rĂ©alisĂ©e et vĂ©rifiĂ©e conforme par l'acheteur public Des avances et acomptes peuvent ĂȘtre versĂ©s : ïŒ L'avance est obligatoire pour les PME sur les marchĂ©s de plus de 50 000 ⏠HT et d'une durĂ©e supĂ©rieure Ă 2 mois. Elle reprĂ©sente 20% du montant pour l'Ătat, 10% pour les autres acheteurs publics ïŒ Les acomptes sont versĂ©s tous les 3 mois maximum, ou tous les mois pour les marchĂ©s de travaux avec des PME
I Le contrat de vente classique 1. LâintĂ©rĂȘt pour la PMI de connaĂźtre la diversitĂ© des contrats commerciaux Les PME-PMI sont rĂ©guliĂšrement amenĂ©es Ă conclure des contrats commerciaux. Il est donc nĂ©cessaire pour lâassistant(e) de gestion de connaĂźtre les diffĂ©rents contrats et les rĂšgles qui les rĂ©gissent. 2. Le transfert de propriĂ©tĂ© DĂšs quâil y a accord entre le vendeur et lâacheteur, il y a transfert de propriĂ©tĂ©. Lâacheteur doit donc assumer les risques dĂšs le transfert de propriĂ©tĂ©. Pour pallier ce risque, il peut prĂ©voir dans le contrat une clause de rĂ©serve en propriĂ©tĂ©, qui a pour effet de diffĂ©rer le transfert de la propriĂ©tĂ© et des risques quâil entraine jusqu'Ă conclusion totale du contrat. 3. Les obligations des parties Les garanties dans le contrat de vente se dĂ©composent ainsi : ï Les garanties obligatoires : o la garantie lĂ©gale de conformitĂ© permettant au client dâobtenir la rĂ©paration, le remboursement ou le remplacement du produit dĂ©fectueux o la garantie contre les vices cachĂ©s : se sont des dĂ©fauts non visibles au moment de lâachat qui rendent le bien inutilisable ï Les garanties complĂ©mentaires ou commerciales : elles sont facultatives pour le client. Elles peuvent ĂȘtre gratuites (mise Ă disposition dâun produit au client durant une rĂ©paration) ou payantes (extension de garantie pour lâachat dâune machine Ă laver) Exercice dâapplication 4. Les recours possibles Lorsquâune procĂ©dure est engagĂ©e, la juridiction compĂ©tente pour statuer lâaffaire est le tribunal de commerce du dĂ©fendeur si le client et lâentreprise sont des commerçants. Les sanctions les plus courantes sont : - infliger des pĂ©nalitĂ©s de retard - obtenir une rĂ©duction de prix - faire exĂ©cuter le contrat par une autre entreprise - obtenir des dommages et intĂ©rĂȘts II Les particularitĂ©s du contrat de vente commerciale Le contrat prĂ©sente certaines particularitĂ©s que la PME doit connaitre : On peut donc considĂ©rer quâun bon de commande est un contrat de vente commerciale, dans la mesure oĂč il rĂ©unit ses clauses. Enfin, il existe des situations ou les engagements peuvent diffĂ©rĂ©s. Câest le cas : - de la vente Ă distance : le client dispose dâun dĂ©lai de rĂ©tractation de 14 jours - la vente avec arrhes : si le client verse des arrhes, il pourra annuler le contrat mais perdra le montant versĂ© Ă lâentreprise. III Les contrats de maintenance et de sous6traitance 1. Le contrat de maintenance Câest un contrat par lequel une entreprise se charge de vĂ©rifier, dâentretenir ou de rĂ©parer un appareil technique ou une installation complexe. Il doit donc spĂ©cifier : - la dĂ©finition de la prestation et le lieu de rĂ©alisation - la durĂ©e du contrat - le prix unitaire ou forfaitaire 2. Le contrat de sous-traitance Il permet Ă une entreprise appelĂ©e « donneur dâordre » de confier la rĂ©alisation dâune prestation Ă une autre entreprise appelĂ©e « sous traitant ». Lâentreprise sâengage Ă payer le sous traitant selon les modalitĂ©s prĂ©vues dans le contrat et reste donc responsable de la rĂ©alisation de la prestation devant le client. Avantages et inconvĂ©nients de la sous-traitance : IV CrĂ©er un contrat via un rĂ©seau de franchise Afin de dĂ©velopper son activitĂ©, lâassistant(e) de gestion peut conclure des contrats commerciaux avec des partenaires Ă©trangers La franchise est une mĂ©thode de collaboration entre, dâune part, une entreprise, le franchiseur, et, dâautre part, une ou plusieurs entreprises, les franchisĂ©s. Son objet est dâexploiter un concept de franchise mis au point par le franchiseur. Tous sont porteurs de la mĂȘme enseigne, symbole de lâidentitĂ© et de la rĂ©putation du rĂ©seau. La garantie de qualitĂ© est assurĂ©e par la transmission et le contrĂŽle du respect du savoir-faire et par la mise Ă disposition dâune gamme homogĂšne de produits, de services et/ou de technologies. a. Le franchiseur Câest un entrepreneur indĂ©pendant qui a mis au point et exploitĂ© avec succĂšs un concept original dans plusieurs unitĂ©s pilotes. Il apporte Ă ses franchisĂ©s une formation initiale et permanente pour leur permettre dâappliquer son concept et consacre Ă la promotion de sa marque, Ă la recherche et Ă lâinnovation, les moyens humains et financiers permettant dâassurer le dĂ©veloppement et la pĂ©rennitĂ© de son concept. b. Le franchisĂ© Câest un entrepreneur indĂ©pendant sĂ©lectionnĂ© par le franchiseur. Il doit avoir la volontĂ© de collaborer loyalement Ă la rĂ©ussite du rĂ©seau de franchise en adhĂ©rant au principe dâhomogĂ©nĂ©itĂ© de ce rĂ©seau, tel que dĂ©fini par le franchiseur. Il engage des moyens financiers, afin de rĂ©tribuer le franchiseur pour ses apports (paiement dâun droit dâentrĂ©e et dâun pourcentage sur le chiffre dâaffaires). c. Les avantages et les inconvĂ©nients du contrat de franchise pour le franchiseur et pour le franchisĂ©. Avantages InconvĂ©nients Franchiseur â DĂ©velopper son rĂ©seau Ă moindres frais. â Faire des Ă©conomies dâĂ©chelle. â MaĂźtriser le dĂ©veloppement de son concept. â DĂ©velopper son image, sa notoriĂ©tĂ©. â Augmenter ses parts de marchĂ©. â AccroĂźtre son chiffre dâaffaires. â Organiser des campagnes publicitaires Ă lâĂ©chelon national. â Transmettre son savoir-faire Ă des commerçants indĂ©pendants. â Assurer une assistance technique et des formations. â Avoir des franchisĂ©s qui dĂ©prĂ©cient lâimage de lâentreprise. FranchisĂ© â Avoir une notoriĂ©tĂ© dĂšs lâouverture du commerce. â Rester un commerçant indĂ©pendant et ĂȘtre responsable de son entreprise. â BĂ©nĂ©ficier du savoir-faire du franchiseur. â BĂ©nĂ©ficier dâune assistance technique, de formations, dâune logistique dâapprovisionnements, etc. â Respecter la charte et les normes du franchiseur, ce qui limite sa libertĂ© de commerçant indĂ©pendant. â Sâacquitter des droits dâentrĂ©e et de redevance. â Avoir une obligation dâapprovisionnement exclusif chez le franchiseur. d. Les clĂ©s de la rĂ©ussite de cette forme de commerce Les clĂ©s de la rĂ©ussite sont : â la collaboration commerciale et technique ; â lâassociation du savoir-faire du franchiseur et de lâesprit entrepreneurial du franchisĂ© ; â les structures organisationnelles sont plus simples et plus Ă©conomiques quâen succursalisme car un bon franchisĂ© est motivĂ© et nâa pas besoin dâĂȘtre poussĂ© ; â câest un systĂšme rapide et Ă©volutif pour couvrir un marchĂ© car investissements et compĂ©tences sont partagĂ©es. e. Les chiffres clĂ©s de la franchise en 2019 f. La typologie des franchisĂ©s âą 60% des franchisĂ©s sont des hommes âą 50% des franchisĂ©s ont entre 35 et 49 ans âą 66% des franchisĂ©s sont dâanciens salariĂ©s du privĂ© âą Chaque franchisĂ© emploie en moyenne 7 salariĂ©s âą 84% des rĂ©seaux sont toujours la propriĂ©tĂ© de leur fondateur âą Chaque rĂ©seau crĂ©e en moyenne 8 nouveaux points de vente par an âą 29% des rĂ©seaux ont des points de vente Ă lâĂ©tranger
Trastorno de la personalidad limite
EVALUER LE RISQUE CLIENT I Les enjeux liĂ©s au risque client II la prise de renseignements pendant la phase commerciale III LâĂ©valuation de la solvabilitĂ© dâun prospect ou client 1. A partir du bilan comptable 2. A lâaide dâindicateurs internes IV Les outils dâĂ©valuation des risques I Les enjeux liĂ©s au risque client 1. DĂ©finition et critĂšres de risques On entend par risque client lâensemble des situations dans lesquelles le client pourrait compromettre la pĂ©rennitĂ© du fournisseur. Quelques critĂšres permettent de repĂ©rer le risque client : - la taille et lâĂąge de lâentreprise - le produit quâelle propose, - son client avec ses propres clients (la sous traitance par exemple induit un lien de dĂ©pendance) - le secteur sur lequel elle Ă©volue - la concurrence quâelle subit - et le montant de ses disponibilitĂ©s On peut ainsi rĂ©partir les degrĂ©s de risque : 2. Les impayĂ©s clients : premiĂšre cause de faillite des entreprises Par principe, lâentreprise dĂ©pense avant dâencaisser. En accordant des dĂ©lais de paiement, elle se prive de trĂ©sorerie. Elle a alors un besoin en fonds de roulement (BFR), c'est-Ă -dire besoin de disposer dâune trĂ©sorerie dâavance. Tout retard de paiement engendre donc une augmentation du BFR que lâentreprise nâest parfois plus en Ă©tat de couvrir (dĂ©couvert bancaire).Lorsque le client est insolvable, câest un manque de trĂ©sorerie qui pĂšse sur lâentreprise et donc sur sa pĂ©rennitĂ©. La PME limite donc les risques si certains de ses clients payent comptant. Les entreprises activent donc plusieurs stratĂ©gies pour faire face Ă leurs impayĂ©s : 29% gĂšrent les relances en interne, 24% nĂ©gocient des facilitĂ©s de caisse avec leur banque et 19% nĂ©gocient avec les fournisseurs. II la prise de renseignements pendant la phase commerciale Lâentreprise qui souhaite conclure un contrat avec un prospect professionnel peut consulter un certain nombre de documents disponibles auprĂšs dâorganismes. Les organismes les plus sollicitĂ©s sont : - la greffe du tribunal de commerce : elle dĂ©livre gratuitement des informations sur les entreprises immatriculĂ©es au registre du commerce et des sociĂ©tĂ©s telles que les statuts, les comptes annuels, lâĂ©tat dâendettement, lâextrait kbis. L'extrait Kbis reprĂ©sente la vĂ©ritable « carte d'identitĂ© » Ă jour d'une entreprise immatriculĂ©e au Registre du Commerce et des SociĂ©tĂ©s (RCS). - les sociĂ©tĂ©s spĂ©cialisĂ©es fournissent des informations commerciales et financiĂšres, des documents comptables et des analyses payantes permettant de vĂ©rifier lâĂ©tat de santĂ© des entreprises : - les cabinets de recouvrement et sociĂ©tĂ©s dâassurance : ils rĂ©alisent des enquĂȘtes de solvabilitĂ© et Ă©mettent un avis sur le risque de dĂ©faillance sous forme de score ou de note. - Les banques : les entreprises sont notĂ©es par les banques. La cotation de la banque mesure la capacitĂ© de lâentreprise Ă honorer ses engagements financiers sur 3 ans. GrĂące Ă cette cotation, la PME peut ainsi , par lâintermĂ©diaire de la banque, vĂ©rifier si le prospect ou client est solide financiĂšrement. III LâĂ©valuation de la solvabilitĂ© dâun prospect ou client La solvabilitĂ© correspond Ă la capacitĂ© de lâentreprise Ă faire face Ă ses engagements Ă long terme. Lâentreprise est solvable si la valeur de ses actifs (immobilisations, crĂ©ances, stocks et disponibilitĂ©s) est supĂ©rieure Ă ses emprunts et dettes. Une entreprise peut ĂȘtre solvable mais peut manquer de liquiditĂ©s, c'est-Ă -dire dâargent disponible au quotidien. La liquidĂ© mesure donc la capacitĂ© de lâentreprise Ă faire face Ă ses engagements Ă court terme. 1. A partir du bilan comptable Le bilan comptable fournit des indications sur la santĂ© financiĂšre de lâentreprise prospect Les dĂ©finitions que vous devez maitriser : âą Pour lâactif : Câest quoi une Immobilisation ? La notion d'immobilisation intĂšgre l'ensemble des biens durables dĂ©tenus par une entreprise sur plus d'un exercice comptable et qui ne sont pas destinĂ©s Ă la revente. Les immobilisations financiĂšres correspondent aux actifs financiers d'utilisation durable possĂ©dĂ©s par l'entreprise. Il s'agit notamment des titres de participation, des prĂȘts accordĂ©s⊠Les immobilisations incorporelles comprennent les frais d'Ă©tablissement, les frais de recherche et dĂ©veloppement, les concessions, brevets, licences, marques, logiciels et autres droits similaires, le droit au bail, le fonds commercial. Une immobilisation corporelle correspond Ă un actif physique que lâentreprise entend utiliser au-delĂ de la clĂŽture de lâexercice comptable en cours : les terrains, les constructions, lâagencement et les installations gĂ©nĂ©rales, lâoutillage, le matĂ©riel, les vĂ©hicules, le mobilier et les Ă©quipements informatiques. Que signifie disponibilitĂ©s ? Le poste "DisponibilitĂ©s" est constituĂ© des montants dĂ©tenus en caisse (piĂšces et billets que l'entreprise possĂšde) et des avoirs en banque (argent dĂ©tenu sur les comptes bancaires de l'entreprise). On utilise Ă©galement le terme de trĂ©sorerie. Câest quoi une valeur mobiliĂšre de placement ? Ce sont des titres financiers, actions ou obligations. En comptabilitĂ©, elles correspondent aux excĂ©dents de trĂ©sorerie placĂ©s par l'entreprise. âą Pour le passif : Que signifie capitaux propres ? Les capitaux propres sont les ressources financiĂšres que possĂšde l'entreprise Le capital social dâune entreprise est Ă©gal au montant total des apports de biens et dâargent des associĂ©s Que signifie rĂ©serves ? Cumul des bĂ©nĂ©fices des exercices antĂ©rieurs qui n'ont pas Ă©tĂ© redistribuĂ©s aux propriĂ©taires de l'entreprise, ni intĂ©grĂ©s dans son capital Que signifie rĂ©sultat ? Il correspond aux ressources restantes Ă l'entreprise une fois les charges dĂ©duites du chiffre d'affaires. 2 A lâaide dâindicateurs internes Une entreprise manque souvent de temps et de moyens pour suivre lâensemble des ses encours clients. Toutefois, il est nĂ©cessaire dâanalyser rĂ©guliĂšrement certains supports pour anticiper les problĂšmes de trĂ©sorerie. Elle peut - analyser son portefeuille clients via la mĂ©thode ABC (vu dans un chapitre prĂ©cĂ©dent), - prendre du recul sur les retards de paiement : le service comptable signale les retards de paiement ou les demandes rĂ©guliĂšres de report dâĂ©chĂ©ances. La balance ĂągĂ©e permet de visualiser les clients Ă relancer Exemple : - mettre en place des indicateurs de suivi des impayĂ©s via un tableau Excel Exemple : IV Les outils dâĂ©valuation des risques Les entreprises peuvent se procurer des logiciels dĂ©diĂ©s au risque client mais il sont souvent trĂšs complexes Ă utiliser. Certaines entreprises utilisent le crĂ©dit management : câest lâensemble des procĂ©dures financiĂšres ou juridiques visant Ă optimiser le chiffre dâaffaires de lâentreprise en accĂ©lĂ©rant les rĂšglements clients. Une des mĂ©thodes de crĂ©dit management sâappelle la mĂ©thode des points de risque. Elle consiste Ă classer les clients selon leur risque afin de leur fixer des modalitĂ©s de paiement adaptĂ©s. Elle permet donc dâĂ©valuer les risques de coopĂ©ration et de se prĂ©munir au cas par cas. Exemple de tableau des points de risque
Le vieillissement est lâensemble des processus physiologiques et psychologiques qui modifient la structure et les fonctions de lâorganisme Ă partir de lâĂąge mĂ»r. Il rĂ©sulte des effets combinĂ©s de facteurs gĂ©nĂ©tiques et environnementaux auxquels est soumis lâorganisme tout au long de sa vie. Il sâagit dâun processus lent et progressif qui est la consĂ©quence de lâaction du temps sur les fonctions de lâorganisme. La sĂ©nescence est le processus de vieillissement biologique, la suite des changements irrĂ©versibles dans un organisme qui conduisent Ă la mort. Ce processus physiologique dĂ©bute aprĂšs la phase de maturitĂ© et se traduit par la dĂ©gradation progressive et inĂ©luctable des fonctions vitales : reproduction, motricitĂ©, systĂšme immunitaire, etc. La sĂ©nilitĂ© est la dĂ©tĂ©rioration pathologique (liĂ©e Ă une maladie) des facultĂ©s physiques et mentales dâun individu ĂągĂ©. Il existe trois modalitĂ©s diffĂ©rentes de vieillissement : le vieillissement rĂ©ussi, avec une absence ou une atteinte minime des fonctions physiologiques et une absence de pathologies ; le vieillissement habituel, avec des atteintes considĂ©rĂ©es comme physiologiques, liĂ©es Ă lâĂąge, de certaines fonctions, mais sans pathologies invalidantes ; le vieillissement pathologique liĂ© Ă des maladies sĂ©vĂšres Ă©volutives ou compliquĂ©es et responsable le plus souvent dâune dĂ©pendance importante. Ă ces trois notions, il est important dâajouter la notion de fragilitĂ© qui correspond Ă un Ă©tat dâĂ©quilibre prĂ©caire avec lâimpossibilitĂ© de rĂ©pondre de façon adaptĂ©e Ă un stress quâil soit mĂ©dical, psychologique ou social. AprĂšs 65 ans, 10 Ă 20% des personnes peuvent ĂȘtre considĂ©rĂ©es comme fragiles et jusquâĂ 50% aprĂšs 85 ans. Il sâagit de personnes Ă haut risque dâhospitalisation, dâinstitutionnalisation et de dĂ©cĂšs. Les psychologues dĂ©crivent 5 grands types de personnalitĂ© liĂ©s au vieillissement, plus ou moins prĂ©sents chez chacun : le mature est actif, tolĂ©rant et il sâadapte parfaitement Ă son Ă©volution ; le pantouflard est passif, indulgent envers lui-mĂȘme et il utilise son Ăąge pour valoriser son inactivitĂ© ; le blindĂ© est mentalement rigide, il a peur de la dĂ©chĂ©ance et sâenferme dans ses souvenirs de jeunesse ; le mĂ©content est amer, intolĂ©rant et pessimiste, anxieux face Ă la mort ; il en veut au monde entier de son Ă©tat et de ses Ă©checs ; le dĂ©prĂ©ciĂ© est dĂ©pressif, insatisfait de sa vie, sans estime de soi et envahi de regrets sur le passĂ© ; il envisage la mort comme une dĂ©livrance ou une finalitĂ©. La solitude a un effet important sur la santĂ©. Si nous comparons des personnes ĂągĂ©es qui conservent un vaste rĂ©seau de relations sociales Ă dâautres qui sont isolĂ©es, ces derniĂšres auraient un risque supĂ©rieur de mort prĂ©maturĂ©e. Parler et Ă©changer avec les autres est essentiel au bien-ĂȘtre. Stimuler la mĂ©moire dâune personne ĂągĂ©e lui permettra de conserver son autonomie et de retarder la dĂ©pendance. Pour rester en forme, le cerveau doit travailler de maniĂšre complĂšte. Plusieurs activitĂ©s peuvent donc permettre Ă la personne dĂ©pendante de garder une bonne mĂ©moire le plus longtemps possible : tenir un agenda, rĂ©diger un journal, jouer Ă des jeux ou encore pratiquer des activitĂ©s de crĂ©ation. Pour stimuler lâactivitĂ© sociale dâune personne ĂągĂ©e, faire des rencontres est le meilleur moyen de rester en forme : rencontrer des personnes, poursuivre les activitĂ©s quâon aime, se servir du tĂ©lĂ©phone et mĂȘme dâinternet si possible. Il y a des personnes ĂągĂ©es qui ne parlent Ă personne pendant des semaines. Pour dâautres, le contact se limite aux relations avec les caissiĂšres des supermarchĂ©s. Avec lâĂąge, certains de nos aĂźnĂ©s sont murĂ©s dans le silence. Pas par choix. Mais parce que les liens familiaux se sont distendus ou nâexistent plus. Ils se retrouvent alors seuls, sans Ă©change, sans partage et sans affection. Un des grands dĂ©fis Ă relever pour lâavenir est la lutte contre la solitude des personnes ĂągĂ©es. Il faut savoir que la solitude est dĂ©sormais considĂ©rĂ©e comme un facteur de risque de la maladie dâAlzheimer. Lutter contre la solitude, câest prĂ©venir lâexclusion, la pauvretĂ© et la perte dâautonomie. Quel est le secret pour prĂ©server son corps malgrĂ© les annĂ©es ? Un peu dâactivitĂ© physique et des repas Ă©quilibrĂ©s ! Pour lutter contre lâapparition des rides ou la chute des cheveux et conserver ses capacitĂ©s physiques et cognitives, mieux vaut surveiller son assiette. Inutile dâaller chercher des produits miracles pour rester jeune : il faut commencer par manger mieux! Car en fonction des aliments quâon choisit, on prĂ©serve son capital santĂ© et on garde la forme durant de longues annĂ©es. Les problĂšmes alimentaires spĂ©cifiques au vieillissement apparaissent Ă des Ăąges variables et sont beaucoup plus marquĂ©s aprĂšs 85 ans. Une bonne nutrition a un rĂŽle de prĂ©vention de mieux en mieux connu sur les pathologies liĂ©es Ă lâĂąge. Un bon rĂ©gime pour un senior comprend beaucoup de fruits et de lĂ©gumes, du pain, du riz, des pĂątes et des fibres. Il ne faut pas oublier le poisson, surtout le thon, le saumon et les sardines, et limiter les viandes rouges, en prĂ©fĂ©rant le poulet, la dinde ou le lapin. Il faut aussi rĂ©duire le sel et le sucre, et tous les aliments riches en graisses comme les frites, les fritures ou les gĂąteaux. Lâeau est trĂšs importante, mais on peut aussi boire du thĂ©, des jus de fruits sans sucre ou du lait Ă©crĂ©mĂ© ou demi â Ă©crĂ©mĂ©. Il faut aussi de la vitamine D pour garder les os en bonne santĂ©. On peut la trouver dans le poisson, la margarine et les cĂ©rĂ©ales du petit dĂ©jeuner. Le corps produit tout seul la vitamine D quand il est exposĂ© au soleil, il est donc conseillĂ© de profiter du soleil de temps en temps avec de la protection pour aider le corps Ă produire cette vitamine. Ătape naturelle de la vie dâune femme, la mĂ©nopause mĂ©rite quelques attentions sur le plan nutritionnel Ă cause de la modification du statut hormonal. Beaucoup de femmes prennent du poids Ă la cinquantaine. Souvent tout simplement parce que leur mode de vie change, avec moins de dĂ©penses physiques et plus de temps pour apprĂ©cier les plaisirs de la table ! Mais aussi parce que les transformations hormonales de la mĂ©nopause vont favoriser la mise en rĂ©serve de graisses. Le premier antidote contre ce risque de surpoids est une activitĂ© physique suffisante et, en complĂ©ment, une alimentation allĂ©gĂ©e grĂące Ă lâĂ©limination des calories «inutiles». Ă Ă©viter ou Ă consommer avec beaucoup de modĂ©ration : les boissons sucrĂ©es comme les sodas, les bonbons, les biscuits salĂ©s ou sucrĂ©s, lâalcool sous toutes ses formes, les glaces et les pĂątisseries, les plats riches en graisses, les frites et les fritures, les sauces classiques, la mayonnaise, les sauces barbecue et tous les laitages au lait entier. Les modifications hormonales et la diminution de lâactivitĂ© physique ont Ă©galement pour consĂ©quence une âfonteâ progressive de la masse musculaire. Pour lutter contre ce phĂ©nomĂšne, il y a une seule solution : bouger !