间质细胞增殖的睾丸内局部调节因子

睾丸间质细胞是男性体内合成雄激素的主要组织细胞.胎儿期睾丸间质细胞从间质前体细胞分化形成,出生后出现由间质干细胞分化形成的第二代睾丸间质细胞,青春期的间质细胞则是由多能间质前体细胞分化而来,经历前体睾丸间质细胞、不成熟睾丸间质细胞、成熟睾丸间质细胞3个不连续的成熟阶段.胎儿期及出生后间质细胞的分化、增殖、发育受多种因素的调节,包括性别决定基因Y、神经细胞黏附分子、转化生长因子、抗苗勒管激素(AMH)等调节;出生后的睾丸间质细胞增殖、发育、成熟除受黄体生成激素调节外,受睾丸局部的雄激素、胰岛素样生长因子1(IGF-1)及自身合成的钙视网膜结合蛋白(calretinin)等因子的调节.     

脂肪因子对睾丸雄激素生成的调节作用

脂肪组织合成和分泌多种脂肪因子(adipokines),通过神经内分泌或直接作用于睾丸来调节生殖系统功能,在睾丸组织已发现多种脂肪因子的受体。瘦素(leptin)在下丘脑-垂体-性腺轴各个层面影响睾丸发育成熟、雄激素合成以及生精功能;脂联素(adiponectin)受体在睾丸组织表达,脂联素影响间质细胞的激素合成,还通过抗炎作用保护间质细胞;同样,抵抗素(resistin)和趋化素(chemerin)也参与调节睾酮合成。肥胖可导致脂肪因子分泌的改变,从而引起胰岛素敏感性下降、慢性炎症、血管病变等代谢相关的改变,也是导致雄激素下降、男性不育的原因之一。     

慢性酒精中毒对男性生殖激素和精液质量的影响

饮酒被认为是一种普通的社会娱乐活动。据报道,男性阳痿、睾丸萎缩、乳房女性化和性欲丧失常与酒精中毒有关,长期酗酒者性欲丧失的患病率为31%￣58%,性功能障碍为8%￣58%。Lemere和Smith曾报道17000例酒精中毒者8%阳痿。此外,酗酒者中还出现精子生成障碍、原发性睾丸功能不全以及代偿性的卵泡刺激素(FSH)、黄体生成激素(LH)分泌增高。酒精对下丘脑-垂体-性腺轴起双重作用。通过直接抑制睾丸类固醇合成和阻碍下丘脑、垂体释放黄体生成激素释放激素(LHRH)、LH。作为一种间质细胞毒素,酒精在增强肝5α-还原酶活性的同时,提高了雄激素的代…     

雄激素缺乏该如何应对

激素的种类有很多.是人体不可或缺的重要生命物质。性激素包括雄激素、雌激素和孕激素.其中雄激素主要是由睾丸的间质细胞(肾上腺和卵巢也有少量分泌)合成和分泌.又称为男性激素。身体自身分泌的雄激素主要以双氢睾酮、睾酮和雄酮的形式分布于机体.主要作用是负责第二性征和副性器官(副性器官是相对于主性器官而言.睾丸和卵巢分别是两性的主性器官)发育.促进精子产生.还参与蛋白质的合成与代谢.促使肌     

睾丸中的精氨酸加压素:性腺内的一种肽类调节系统

本文评述神经垂体激素对睾丸机能的调节。根据离体条件下对睾丸雄激素生物合成的影响,在大鼠睾丸中存在精氨酸加压素(AVP)样物质以及AVP降解酶等发现,提示AVP可能作为一种性腺内的肽起到在局部调制雄激素生物合成的作用。AVP在调制睾丸Leydig细胞甾体生物合成方面的自身分泌(autocrine)或旁分泌(paracrine)作用可以作为一个范例,用于理解性腺内的局部激素调节机制。神经垂体激素抑制睾丸雄激素合成:Leydig细胞是睾丸内的主要雄激素产生细胞,其甾体生成机能主要受垂体LH的调节。此外,许多别的因素也必定调节着Leydig细胞对LH的反应性。除     

小知识(7)

男性性发育 (ｓｅｘｄｅｖｅｌｏｐｍｅｎｔｉｎｍａｌｅ)　男性性发育包括内外生殖器官的形态、功能发育和第二性征的发育。在青春期前这些器官的发育几乎处于静止状态。进入青春期后在卵泡刺激素 (ＦＳＨ)、黄体生成激素 (ＬＨ)及雄激素的作用下迅速发育。睾丸精曲小管在 10岁左右才出现管腔 ,但管壁仅有未分化的支持细胞和少量精原细胞 ;青春期后小管长度增加、管腔增粗 ,出现各期生精细胞并开始产生精子 ;精曲小管间质细胞分泌大量雄激素和少量雌激素。输精管也增长增粗 ,精子离开睾丸进入附睾 ,进一步分化成熟。前列腺、尿道球腺也成熟…     

雄激素及其受体在前列腺癌发生发展中的作用

前列腺发生于泌尿生殖窦上皮 ,是雄激素依赖的器官。雄激素及其受体在前列腺的发生、生长、分化和功能的维持上起着重要的作用。雄激素 (Ｔ)主要由睾丸间质细胞 (ＬｅｙｄｉｇＣｅｌｌ)合成、分泌 ,通过 5α 还原酶 (主要是Ⅱ型 )的作用能转化成更具生物活性的脱氢睾酮 (ＤＨＴ)。除了睾丸 ,肾上腺也能分泌一定量的无活性的甾类激素前体物质如脱氢 (表 )雄甾酮 (ＤＨＥＡ)和雄甾烯二酮等。这些前体物质能在许多组织包括前列腺中被转化生成Ｔ。这些肾上腺来源的雄激素在前列腺及前列腺癌的发生、发展中起到什么作用目前尚未见相关报道。1　前…     

如何诊断男性更年期综合征

衰老是生命过程的自然规律。近年来,由内分泌科、男科专家和老年医学科专家做了大量研究证明:男性衰老源于雄激素合成和分泌不足,睾丸的老化是雄激素合成和分泌不足的主要原因,还有垂体分泌的黄体生成素的减少以及睾丸间质细胞萎缩等。男性从50岁左右开始,体内生物活性的游离睾酮和以白蛋白结合形式的睾酮,每年以1.2%、1.0%下降;相反,结合睾酮的无活性性激素结合球蛋白每年以1.2%增加。睾酮的分泌昼夜节律也随着衰老而改变。随着年龄的增长,有生物活性的游离睾酮下降,会     

糖尿病与男性生殖内分泌

睾丸主要功能是产生精子、分泌雄激素,男性性激素主要是以睾酮为主的雄激素,还包括卵泡刺激素、黄体生成激素、雌二醇、泌乳素等生殖激素.糖尿病是一种以长期高血糖为主要特征的代谢综合征,由于胰岛素缺乏或胰岛素生物作用障碍导致糖代谢紊乱,同时伴有脂肪、蛋白质、水、电解质等代谢障碍,其中2型糖尿病(T2DM)占90％以上.长期患糖尿病可导致各种组织,特别是眼、肾、心脏、血管、神经的慢性损害和功能障碍,男性糖尿病患者还可能伴有生殖内分泌系统损害.糖尿病患者雄激素浓度较正常人低,性激素异常,可表现为勃起功能障碍、性欲减退等症状,而雄激素降低又通过一系列的生理、生化影响,加重患者的代谢紊乱,并成为动脉粥样硬化及冠心病的危险因素之一.综述男性糖尿病患者的生殖内分泌异常,以期为糖尿病及其并发症的治疗提供参考.     

男性生殖毒性评价指标研究进展

环境因素,特别是职业性有害因素,对男性生殖的不良影响已受到日益重视。随着对正常男性生殖系统生理、生化过程认识的深入,有关男性生殖功能的评价指标亦得到了完善和发展。本文对这些指标的研究和应用进展做一综述,以供参考。 一、内分泌检查 与男性生殖功能有关的激素,主要有下丘脑分泌的促性腺释放激素(GnRH)、垂体前叶分泌的促卵泡成熟激素(FSH)、黄体生成素(CH)、催乳素(PRL)及睾丸间质细胞(Leydig)分泌的睾酮(T)。研究发现,多种有害因素可致血中性激素水平发生异常改变。例如酒精可以影响雄激素合成酶系的活性和Leydig细胞上LH受体的敏感性从而导致血中睾酮水平下降:职业性长期接触铅的工人则有FSH升高趋势。近年来的研究发现,精囊具有分泌PRL的可能性,因此推测PRL除具有增加精子内第二信使CAMP(环磷酸腺苷)含量的作用外,还可能与精囊的功能有关。GnRH则具有对中枢神经和雄激素分泌直接发挥作用的可能性。     

Calcium intake in the elderly: validation of a dietary questionnaire

Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly.     

The occurrence of antimicrobial substances in toilet,sink and shower drainpipes of clinical units: A neglected source of antibiotic residues

Antibiotics represent one of the most important drug groups used in the management of bacterial infections in humans and animals. Due to the increasing problem of antibiotic resistance, assurance of the antibacterial effectiveness of these substances has moved into the focus of public health. The reduction in antibiotic residues in wastewater and the environment may play a decisive role in the development of increasing rates of antibiotic resistance. The present study examines the wastewater of 31 patient rooms of various German clinics for possible residues of antibiotics, as well as the wastewater of five private households as a reference.To the best of our knowledge, this study shows for the first time that in hospitals with high antibiotic consumption rates, residues of these drugs can be regularly detected in toilets, sink siphons and shower drains at concentrations ranging from 0.02?μg·L^?1 to a maximum of 79?mg·L^?1. After complete flushing of the wastewater siphons, antibiotics are no longer detectable, but after temporal stagnation, the concentration of the active substances in the water phases of respective siphons increases again, suggesting that antibiotics persist through the washing process in biofilms. This study demonstrates that clinical wastewater systems offer further possibilities for the optimization of antibiotic resistance surveillance.     

Self-reported health problems among Swedish miners one year after unemployment

Unemployment is considered to be a public health concern sincedeterioration in the health of the unemployed is often anticipated.However, for some groups, such as miners, unemployment mightimprove health due to a cessation of potentially harmful occupationalexposures. This study evaluates the health of 79 miners in oneSwedish iron-ore mine, and 226 age-matched controls from thegeneral population, during one year after the closure of themine. The participants received a questionnaire regarding medicalhistory and subjective symptoms at the beginning of the studyperiod, and after one year. Statistically significant negativeeffects on self-reported health attributable to unemploymentwere not found, although neuropsychiatric symptoms were morecommon among the unemployed miners. The miners reported a statisticallysignificant improvement in grip force (p=0.031). They had asignificantly higher prevalence of symptoms associated withmining related exposures when compared with the population controls;pain in the upper extremities [relative risk (RR)=2.27, 95%confidence interval (Cl)=1.44–3.59), back pain (RR=1.84;Cl=1.237–2.75), vasospastic disease of the fingers (RR=2.05;Cl=1.18–3.57) and obstructive respiratory symptoms (attacksof dyspnea and wheezing: RR=3.67; Cl=1.167–11.6).     

Excès de cas humains et animaux de tularémie en France au cours de l’hiver 2007–2008 : émergence ou phénomène isolé ?

Context

Tularemia is a zoonosis affecting humans and hares in France. We describe the results of surveillance in both species, in 2007 and 2008.

Methods

Human tularemia cases are mandatorily notifiable in France since 2003. In hares, surveillance relies on volunteer hunter associations in all districts of the country. Data from mandatory reports and volunteer surveillance in 2007/2008 were analyzed and compared with previous results.

Results

In 2007/2008, 144 cases were reported in humans and 117 cases in hares. This was a 100% increase compared to previous years. Human cases differed from those of previous years only by the frequency of contact with breeding animals. Human cases without any documented risk exposure were also more frequent.

Conclusion

An increase of tularemia cases occurred in 2007/2008 in both species. Complementary studies are needed to identify the species reservoir in France to understand the causes of this peak of cases.     

Occupational health hazards in mining: an overview

This review article outlines the physical, chemical, biological, ergonomic and psychosocial occupational health hazards of mining and associated metallurgical processes. Mining remains an important industrial sector in many parts of the world and although substantial progress has been made in the control of occupational health hazards, there remains room for further risk reduction. This applies particularly to traumatic injury hazards, ergonomic hazards and noise. Vigilance is also required to ensure exposures to coal dust and crystalline silica remain effectively controlled.     

Manufacture and use of nanomaterials: current status in the UK and global trends

This paper provides an overview of the production and use of nanomaterials (NMs), particularly in the UK. Currently, relatively few companies in the UK are identifiable as NM manufacturers, the main emphasis being the bulk markets in metals and metal oxides, and some niche markets such as carbon nanotubes and quantum dots. NM manufacturing in the UK does not reflect the global emphasis on fullerenes, nanotubes and fibres. Some assumptions have been made about the types of NM that are likely to be imported into the UK, which currently include fullerenes, modified fullerenes and other carbon-based NMs including nanotubes. Many university departments, spin-offs and private companies have developed processes for the manufacture of NMs but may only be producing small quantities for research and development (R&D) purposes. However, some have the potential to scale up to produce large quantities. The nanotechnology industry in the UK has strong R&D backup from universities and related institutions. This review has covered R&D trends at such institutions, and appropriate information has been added to a searchable database. While several companies are including NMs in their products, only a few (e.g. manufacturers of paints, coatings, cosmetics, catalysts, polymer composites) are using nanoparticles (NPs) in any significant quantities. However, this situation is likely to change rapidly. There is a need to collect more information about exposure to NPs in both manufacturing and user scenarios. As the market grows, and as manufacturers switch from the micro- to the nanoscale, the potential for exposure will increase. More research is required to quantify any risks to workers and consumers.     

深圳公立医院管理体制改革制度设计

深圳公立医院管理体制改革实行政事分开、管办分开,在理事会架构下按法定机构模式组建市医管中心,落实公立医院运营管理自主权.作者从当前公立医院管理体制的弊端入手,介绍了深圳市进行公立医院管理体制改革的基本思路及改革方案设计的主要举措,深入剖析了的改革方案的特点,并对改革效果进行了预测.     

Effects of nitrogen dioxide on red blood cells of rats: Changes in components of red cell membranes during in vivo exposure to NO2

Red cell membranes, prepared from red blood cells of rats exposed to 4, 10, or 20 ppm nitrogen dioxide (NO₂) for 1 to 10 days, were examined for evidence of changes in membrane components. Appreciable changes were not found in contents of phospholipid and cholesterol during exposure to 10 ppm NO₂. By contrast, protein content altered with the time of exposure. Moreover, changes in protein composition were observed by employing sodium dodecyl sulfate — polyacrylamide gel electrophoresis. Twenty-four-hour exposure to NO₂ at the concentration above 10 ppm resulted in a marked increase in the percentage of lysophosphatidylethanolamine (LysoPE) to the total phospholipids. The prolonged exposure to 10 ppm NO₂ gave rise to a further increase in LysoPE, whereas the percentage of phosphatidylethanolamine (PE) showed a gradual decrease. A 1-day exposure to 4.0 ppm NO₂ also caused an increase in sialic acid content and decreases in those of PE and hexose. In addition to contents of these components the percentage of LysoPE increased 5 days after exposure and the elevated values were maintained up to the end of exposure period. These results demonstrate that red blood cells in circulation exhibit different membrane properties in terms of lipid and carbohydrate composition during 10 days of exposure to 4.0 ppm NO₂.     

Investigating clusters in the workplace and beyond

Clusters of disease are common and occur in the workplace and in the general community. They often arouse considerable concern among the population. Investigations have sometimes lead to exciting new knowledge, but in general the investigation of clusters is difficult and often unrewarding, especially for community clusters. In the workplace, investigations are more likely to find associations and even new causes, but still many clusters remain enigmatic. Despite this, there are many reasons for investigating clusters, including allaying community concern and identifying uncontrolled exposures. A structure for investigating clusters in the workplace is suggested.