2010—2011年兰州地区5岁以下腹泻患儿杯状病毒和腺病毒感染的流行特征

目的了解兰州地区腹泻患儿中杯状病毒和腺病毒感染的分子流行病学及临床特点。方法收集兰州大学第一医院2010年7月至2011年6月腹泻患儿粪便标本295份,采用RT-PCR或PCR的方法检测杯状病毒及腺病毒,腺病毒阳性标本利用多重PCR及巢式PCR的方法分型,并对序列进行分析。结果295份粪便标本中杯状病毒的检出率为13．2％（39／295）,腺病毒的检出率是5．1％（15／295）。分型结果显示：杯状病毒中69．2％为诺如病毒,其余是札如病毒,诺如病毒中以GII-3（13例）为主,其次为GII-4（12例）,GII-6（2例）;腺病毒主要以F组的41型（10／15）为主,同时还检测到1例A组的31型,2例B组的3型及C组的1例5型和1例6型,两种病毒均主要感染2岁以下儿童,无明显的季节高峰。结论杯状病毒和腺病毒是2010—2011年兰州地区病毒性腹泻患儿的重要病原,长期监测具有重要意义。     

兰州地区5岁以下婴幼儿病毒性腹泻的分子流行病学研究

目的调查兰州地区5岁以下婴幼儿病毒性腹泻的流行情况,了解四种主要腹泻病毒在儿童中的分布情况。方法采集2009年7月至2010年6月兰州大学第一医院儿科5岁以下腹泻患儿粪便标本290份及儿童保健中心健康婴幼儿正常粪便标本114份,采用酶联免疫吸附试验（ELISA）检测轮状病毒抗原,采用巢式聚合酶链反应对轮状病毒阳性标本进行分型;采用反转录．聚合酶链反应（RT—PCR）检测杯状病毒和星状病毒,聚合酶链反应（PCR）检测腺病毒。结果290份腹泻标本中四种病毒的阳性率分别为：轮状病毒39．31％,杯状病毒11．38％,腺病毒10．69％,星状病毒4．83％;对114份轮状病毒阳性标本G、P分型,G3型及P[8]型为优势株;114份正常标本轮状病毒检出率为0,杯状病毒检出7例,星状病毒检出1例,腺病毒检出5例。结论病毒性病原在兰州地区婴幼儿腹泻中占有重要地位,长期系统的监测具有重要意义。     

南京地区婴幼儿杯状病毒感染的分子流行病学研究

目的了解南京地区婴幼儿杯状病毒腹泻的感染状况、临床表现以及分子流行病学特征。方法采集2010年7月至2011年6月南京医科大学附属南京儿童医院5岁以下腹泻患儿粪便标本及儿童保健中心健康婴幼儿粪便标本各428份。采用反转录-聚合酶链反应（RT—PCR）检测杯状病毒,测序确定其基因型别。结果428份腹泻样本中有63份为杯状病毒阳性,检出率为14．72％。其中诺如病毒GⅡ型58例,未检出诺如病毒GI型,札如病毒5例,以诺如病毒GⅡ-42006b型为主要流行株。428份健康对照组标本杯状病毒检出19例,诺如病毒6例,札如病毒11例,2例为诺如病毒GⅡ型和札如病毒混合感染。结论南京地区婴幼儿中存在不同基因型杯状病毒感染,流行毒株以GⅡ-2006b为主。     

南京地区婴幼儿杯状病毒感染的分子流行病学研究

目的 了解南京地区婴幼儿杯状病毒腹泻的感染状况、临床表现以及分子流行病学特征.方法 采集2010年7月至2011年6月南京医科大学附属南京儿童医院5岁以下腹泻患儿粪便标本及儿童保健中心健康婴幼儿粪便标本各428份.采用反转录-聚合酶链反应( RT-PCR)检测杯状病毒,测序确定其基因型别.结果 428份腹泻样本中有63份为杯状病毒阳性,检出率为14.72％.其中诺如病毒GⅡ型58例,未检出诺如病毒GⅠ型,札如病毒5例,以诺如病毒GⅡ-4 2006b型为主要流行株.428份健康对照组标本杯状病毒检出19例,诺如病毒6例,札如病毒11例,2例为诺如病毒GⅡ型和札如病毒混合感染.结论 南京地区婴幼儿中存在不同基因型杯状病毒感染,流行毒株以GⅡ.2006b为主.     

长春地区2010年度婴幼儿腹泻的病原学研究及流行病学特点

目的 了解长春地区四种主要腹泻病毒病原构成及流行病学特点.方法 收集长春市儿童医院5岁以下住院患儿腹泻样本共460例,轮状病毒采用ELISA试剂盒检测,杯状病毒、星状病毒采用逆转录-聚合酶链反应( RT-PCR)法,腺病毒采用聚合酶链反应(PCR)法进行鉴定.结果 460份标本中轮状病毒占35.22％( 162/460);杯状病毒占20.43％( 94/460),星状病毒占9.78％(45/460),腺病毒占3.70％(17/460),混合感染达7.17％(33/460),发病患儿以2岁以下婴幼儿为主.对162份轮状病毒阳性标本进行G/P分型,结果示G1P[8]为主要流行株,杯状病毒以GⅡ-4亚型为主要流行株,星状病毒为Ⅰ型,腺病毒为Ad41.结论 长春地区婴幼儿病毒性腹泻的病原中轮状病毒是最主要病原,其次为杯状病毒、星状病毒和腺病毒.     

北京市肠道门诊腹泻患者人杯状病毒感染调查

目的 调查北京地区肠道门诊就诊腹泻患者人杯状病毒的感染情况.方法 收集北京市2011年4月至2012年3月丰台、昌平、怀柔3个区县的肠道门诊就诊腹泻患者450例,采集患者粪便标本,使用逆转录聚合酶链反应法(RT-PCR)对粪便标本进行人杯状病毒RNA检测,对RT-PCR阳性标本的PCR产物进行克隆测序.结果 450例患者标本中68例人杯状病毒阳性(68/450,15.11％).选择其中18例PCR产物进行克隆测序,将获得的序列进行比对分析、构建系统发生树,结果表明,15株为诺如病毒,3株为扎如病毒.其中诺如病毒GⅡ/4型11株(11/18,61.11％),GⅡ/7型1株(1/18,5.56％),GⅡ组未定型3株(3/18,16.67％).结论 人杯状病毒是北京地区肠道门诊就诊腹泻患者的重要病原,主要流行株为诺如病毒GⅡ/4型.     

2006-2015年成都地区5岁以下病毒性腹泻住院患儿病原学特征分析CSCD

目的 对成都地区5岁以下急性腹泻病患儿进行病毒学监测,了解引起腹泻常见病毒的流行特征,为指导病毒性腹泻的防控提供科学依据.方法 采集成都市妇女儿童中心医院儿童消化科2006年3月至2015年6月5岁以下腹泻住院患儿粪便标本,并送四川省疾病预防控制中心进行病毒RNA提取与检测,并记录患儿临床资料.采用ELISA、RT-PCR方法对轮状病毒抗原进行检测与分型;采用RT-PCR方法对杯状病毒、星状病毒、腺病毒进行检测与分型.结果 共收集1-59月龄腹泻住院患儿粪便标本份共2 331份（男1 446份,女885份）,阳性检出率58.0％,以7-12月龄为好发年龄.轮状病毒阳性检出率28.3％,11 -12月份为流行季节.杯状病毒阳性检出率23.3％,9月份为流行季节,诺如病毒GII为主要感染株,未发现暴发流行.星状病毒阳性检出率1.5％,主要于1-3月份检出.腺病毒阳性检出率5.1％,主要于5-8月份检出,2011年有过小流行.2007年以后,轮状病毒的检出率较前明显下降,而同时杯状病毒检出率逐年升高,2010-2015年杯状病毒成为引起5岁以下患儿腹泻的主要病毒之一.绝大多数病毒性腹泻患儿为急性病程（91.2％）,以轻度脱水为主,其次为中度脱水,无重度脱水.可伴消化道外表现,轮状病毒的消化道外表现较杯状病毒多见,但在随访中均恢复正常.结论 病毒性腹泻是5岁以下儿童急性腹泻病常见原因,成都地区以轮状病毒、杯状病毒为主要病原体.     

安徽池州地区小儿腹泻病毒病原学研究

目的 了解安徽池州市小儿腹泻的主要病毒病原.方法 采集2005年1月至2006年12月间在安徽池州市人民医院儿科住院的428例小儿腹泻患者粪便标本,采用酶免疫分析或ELISA法分别检测轮状病毒、星状病毒、腺病毒或杯状病毒抗原.对轮状病毒进行病毒株血清学检测,并采用RT-PCR进行基因分型.结果 安徽池州小儿腹泻常见的病毒病原检出率分别为轮状病毒29.2%、杯状病毒10.5%、腺病毒2.4%.其中,混合感染率为2.4%.同时比较用PCR及ELISA两种方法检查44份粪便标本中轮状病毒,结果两种方法检查一致率达97.7%.对48株轮状病毒G血清型分型结果是血清Ⅰ型3份、Ⅱ型1份、Ⅲ型35份、Ⅸ型2份、未能分型7份.分别来自2005年26份可分型、2006年15份可分型,2年中均以RV Ⅲ型占绝大多数(分别为24株、11株),其他型别仅占少数.对8株轮状病毒P分型,其中7株为G3P8,1株为G9P8.轮状病毒感染具有明显季节性,以冬、春季多,杯状病毒似乎以秋季多.结论 安徽池州地区小儿腹泻的病毒病原中以轮状病毒为主,杯状病毒次之,腺病毒检出率低.两年中流行的轮状病毒以G3型为主,G3P8多.     

2014-2015年河北省5岁以下婴幼儿病毒性腹泻病原学监测及流行特征分析

目的 了解河北省5岁以下婴幼儿病毒性腹泻病原构成及流行特点,为病毒性腹泻的防治提供参考依据.方法 收集河北省哨点医院2014年1月-2015年12月0-59月龄腹泻患儿粪便标本686份,同时填写个案调查表,采用ELISA方法检测轮状病毒(HRV),采用PCR或RT-PCR法检测杯状病毒(HuCV)、星状病毒(HAstV)和肠道腺病毒(HAdV),并对轮状和杯状阳性标本进行分型鉴定.结果 686份标本病毒性病原总检出率64.14％ (440/686),2014年62.71％(222/354),稍低于2015年的65.66％ (218/332) (x2=0.649,P=0.421),其中单纯轮状、杯状、星状和肠道腺病毒检出率分别为35.13％(241/686)、11.37％(78/686)、1.75％(12/686)和4.96％(34/686),合并感染率10.93％(75/686)(合并2种69份,合并3种6份).轮状病毒阳性检出率以13-24月龄最高(x2=22.289,P＜0.001),随月龄增长呈现先升高后降低趋势,且季节性分布明显,秋冬季(11月-次年2月)高发,以G9P[8]型为主(87.95％,270/307).杯状病毒全年呈多峰分布,3-6月份检出率较高,2015年(24.70％,82/332)高于2014年(13.56％,48/354)(x2=13.841,P＜0.001).结论 河北省5岁以下儿童病毒性腹泻病原复杂,混合感染比例较大,轮状病毒为主要致病病原体,该病毒主要侵犯2岁以下儿童,秋冬季高发,其中G9P[8]型成为本地区主要流行株.     

太原市5岁以下腹泻住院儿童的病毒病原及其流行特征

目的 了解山西省太原市5岁以下腹泻住院儿童四种主要腹泻病毒的流行情况.方法 收集山西儿童医院2007年10月至2008年11月5岁以下全部住院腹泻患儿的粪便标本,采用ELISA试剂盒来检测轮状病毒;采用聚合酶链反应（PCR）检测腺病毒;逆转录-聚合酶链反应（RT-PCR）法检测星状病毒和杯状病毒并对轮状病毒进行分型.结果 346份标本中轮状病毒占40.8%、杯状病毒占7.5%、星状病毒占6.4%、腺病毒占3.2%.对141份轮状病毒阳性标本进行G1P分型,G1型是最优势株,P型优势株为P[8].四种病毒主要是感染2岁以下婴幼儿,RV有明显的季节的特征,9-11月份（48.92%）为发病高峰.结论 轮状病毒为最主要的病毒病原,G1P[8]型为主要流行株,秋冬季为发病高峰,2岁以下为发病高危人群,混合感染多见.     

Opportunities and challenges in the prevention and control of cancer and other chronic diseases: children's diet and nutrition and weight and physical activity

OBJECTIVE: The purpose of this article is to review the role of behavioral research in disease prevention and control, with a particular emphasis on lifestyle- and behavior-related cancer and chronic disease risk factors--specifically, relationships among diet and nutrition and weight and physical activity with adult cancer, and tracking developmental origins of these health-promoting and health-compromising behaviors from childhood into adulthood. METHOD: After reviewing the background of the field of cancer prevention and control and establishing plausibility for the role of child health behavior in adult cancer risk, studies selected from the pediatric published literature are reviewed. Articles were retrieved, selected, and summarized to illustrate that results from separate but related fields of study are combinable to yield insights into the prevention and control of cancer and other chronic diseases in adulthood through the conduct of nonintervention and intervention research with children in clinical, public health, and other contexts. RESULTS: As illustrated by the evidence presented in this review, there are numerous reasons (biological, psychological, and social), opportunities (school and community, health care, and family settings), and approaches (nonintervention and intervention) to understand and impact behavior change in children's diet and nutrition and weight and physical activity. CONCLUSIONS: Further development and evaluation of behavioral science intervention protocols conducted with children are necessary to understand the efficacy of these approaches and their public health impact on proximal and distal cancer, cancer-related, and chronic disease outcomes before diffusion. It is clear that more attention should be paid to early life and early developmental phases in cancer prevention.     

Pain and Effusion and Quadriceps Activation and Strength

Context:

Quadriceps dysfunction is a common consequence of knee joint injury and disease, yet its causes remain elusive.

Objective:

To determine the effects of pain on quadriceps strength and activation and to learn if simultaneous pain and knee joint effusion affect the magnitude of quadriceps dysfunction.

Design:

Crossover study.

Setting:

University research laboratory.

Patients or Other Participants:

Fourteen (8 men, 6 women; age = 23.6 ± 4.8 years, height = 170.3 ± 9.16 cm, mass = 72.9 ± 11.84 kg) healthy volunteers.

Intervention(s):

All participants were tested under 4 randomized conditions: normal knee, effused knee, painful knee, and effused and painful knee.

Main Outcome Measure(s):

Quadriceps strength (Nm/kg) and activation (central activation ratio) were assessed after each condition was induced.

Results:

Quadriceps strength and activation were highest under the normal knee condition and differed from the 3 experimental knee conditions (P < .05). No differences were noted among the 3 experimental knee conditions for either variable (P > .05).

Conclusions:

Both pain and effusion led to quadriceps dysfunction, but the interaction of the 2 stimuli did not increase the magnitude of the strength or activation deficits. Therefore, pain and effusion can be considered equally potent in eliciting quadriceps inhibition. Given that pain and effusion accompany numerous knee conditions, the prevalence of quadriceps dysfunction is likely high.Key Words: arthrogenic muscle inhibition, central activation failure, voluntary activation, muscles

Key Points

• Knee pain and effusion resulted in arthrogenic muscle inhibition and weakness of the quadriceps.
• The simultaneous presence of pain and effusion did not increase the magnitude of quadriceps dysfunction.
• To reduce arthrogenic muscle inhibition and improve muscle strength, clinicians should employ interventions that target removing both pain and effusion.

Quadriceps weakness is a common consequence of traumatic knee joint injury^1,2 and chronic degenerative knee joint conditions.^3,4 Arthrogenic muscle inhibition (AMI), a neurologic decline in muscle activation, results in quadriceps weakness and hinders rehabilitation by preventing gains in strength.⁵ The inability to reverse AMI and restore muscle function can lead to decreased physical abilities,⁶ biomechanical deficits,⁷ and possibly reinjury.⁵ Furthermore, researchers^8,9 have suggested that quadriceps weakness resulting from AMI may place patients at risk for developing osteoarthritis in the knee. In light of the substantial influence of quadriceps AMI on these clinically relevant outcomes, we need to improve our understanding of the factors that contribute to this neurologic decline in muscle activity so efforts to target and reverse it can be implemented and gains in strength can be achieved more easily.Joint injury and disease are accompanied by numerous sequelae (ie, pain, swelling, tissue damage, inflammation), so ascertaining which one ultimately leads to neurologic muscle dysfunction is difficult. Whereas a joint effusion can result in AMI,^10–12 the effects of pain are less understood despite many clinicians attributing AMI to pain. Using techniques that introduce knee pain without accompanying injury may provide insights into the role of pain in eliciting AMI.The degree of knee joint damage may play a role in the quantity of AMI that manifests. Hurley et al^13,14 demonstrated that quadriceps AMI, measured using an interpolated-twitch technique, was greater in patients with extensive traumatic knee injury (eg, fractured tibial plateau, ruptured medial collateral ligament, and medial meniscectomy) than patients with isolated joint trauma (ie, isolated anterior cruciate ligament [ACL] rupture). Similarly, patients with more knee joint symptoms (ie, greater number of symptoms and increased severity of symptoms) may present with greater magnitudes of quadriceps inhibition. Recently, investigators¹⁵ have suggested that patients with more pain display less quadriceps strength, supporting this tenet. Given that effusion and pain often present simultaneously with joint injuries and diseases, such as ACL injury and osteoarthritis, examining both the isolated and cumulative effects of these sequelae appears warranted to determine if they influence the magnitude of muscle inhibition.Experimental joint-effusion and pain models are safe and effective experimental methods that allow for the isolated examination of their effects on muscle function. The effusion model, whereby sterile saline is injected directly into the knee joint capsule,⁷ produces a clinically relevant magnitude of the joint effusion that may be present with traumatic injury. Effusion is thought to activate group II afferents responding to stretch or pressure,^16–18 which in turn may facilitate group Ib interneurons and result in quadriceps AMI.⁵ The pain model involves injecting hypertonic saline into the infrapatellar fat pad to produce anteromedial knee pain similar to that described in patients with patellofemoral pain syndrome.¹⁹ Pain is considered to initiate AMI through activation of group III and IV afferents that act as nocioceptors to signal damage or potential damage to joint structures.^16–18 The firing of these afferents then may lead to facilitation of group Ib interneurons, the flexion reflex, or the gamma loop, ultimately resulting in quadriceps inhibition.²⁰ Thus, these models allow us to create symptoms that are associated with knee injury and have the added benefit of providing a way to examine their effects in isolation.Therefore, the purpose of our study was to determine the effects of pain on quadriceps strength and activation and to learn if simultaneous pain and knee joint effusion would affect the magnitude of quadriceps dysfunction. We hypothesized that pain alone would result in quadriceps inhibition and that the magnitude of inhibition would be greater when effusion and pain were present simultaneously.     

Postinfectious immunodeficiency and autoimmunity: pathogenic and clinical values and implications

Autoimmunity is still a mystery of clinical immunology and medicine as a whole. The etiology and pathogenesis of autoimmune disorders remain unclear and, thus, are assessed as a balance between hereditary predisposition, triggering factors and the appearance of autoantibodies and/or self-reactive T cells. Among the immunological armamentarium, molecular mimicry, based on self-reactive T- and B-cell activation by cross-reactive epitopes of infectious agents, is of special value. Hypotheses regarding the possible involvement of molecular mimicry in the development of postinfectious autoimmunity are currently very intriguing. They provide new approaches for identifying etiological agents that are associated with postinfectious autoimmunity, paired microbial- and tissue-linked epitopes targeted for autoimmune reaction determination, postinfectious autoimmunity pathogenesis recognition and specific prevention, and therapy for autoimmune disorder development.     

Beta-endorphin and drug-induced reward and reinforcement

Although drugs of abuse have different acute mechanisms of action, their brain pathways of reward exhibit common functional effects upon both acute and chronic administration. Long known for its analgesic effect, the opioid beta-endorphin is now shown to induce euphoria, and to have rewarding and reinforcing properties. In this review, we will summarize the present neurobiological and behavioral evidences that support involvement of beta-endorphin in drug-induced reward and reinforcement. Currently, evidence supports a prominent role for beta-endorphin in the reward pathways of cocaine and alcohol. The existing information indicating the importance of beta-endorphin neurotransmission in mediating the reward pathways of nicotine and THC, is thus far circumstantial. The studies described herein employed diverse techniques, such as biochemical measurements of beta-endorphin in various brain sites and plasma, and behavioral measurements, conducted following elimination (via administration of anti-beta-endorphin antibodies or using mutant mice) or augmentation (by intracerebral administration) of beta-endorphin. We suggest that the reward pathways for different addictive drugs converge to a common pathway in which beta-endorphin is a modulating element. beta-Endorphin is involved also with distress. However, reviewing the data collected so far implies a discrete role, beyond that of a stress response, for beta-endorphin in mediating the substance of abuse reward pathway. This may occur via interacting with the mesolimbic dopaminergic system and also by its interesting effects on learning and memory. The functional meaning of beta-endorphin in the process of drug-seeking behavior is discussed.     

PTEN与信号转导及肿瘤

ＴＥＮ[1] (ｐｈｏｓｐｈａｔａｓｅａｎｄｔｅｎｓｉｎｈｏｍｏｌｏｇｙｄｅｌｅｔｅｄｏｎｃｈｒｏｍｏｓｏｍｅｔｅｎ)又名ＭＭＡＣ1 [2 ] (ｍｕｔａｔｅｄｉｎｍｕｔｉｐｌｙａｄａｎｃｅｄｃａｎｃｅｒ 1 )和ＴＥＰ1 [3 ] (ＴＧＦ -βｒｅｇｕｌａｔｅｄａｎｄｅｐｉｔｈｅｌｉａｌｃｅｌｌ -ｒｉｃｈｅｄｐｈｏｓｐｈａｔａｓｅ 1 ) (以下均称为ＰＴＥＮ) ,是 1 997年由 3个研究小组先后发现的一个具有双特异磷酸酶活性的抑癌基因。ＰＴＥＮ基因异常广泛存在于人类多种恶性肿瘤 ,如恶性神经胶质瘤、前列腺癌、子宫内膜癌、黑色素瘤等…     

Tobacco and alcohol and the risk of head and neck cancer

Summary We carried out two case-control studies on the relative risk of head and neck cancer in association with tobacco and alcohol consumption. The first study carried out at the ENT Department of the University hospitals of Heidelberg and Giessen (FRG) comprised 200 male patients with squamous cell cancer of the head and neck and 800 control subjects matched for sex, age, and residential area (1:4 matching design). Of the tumour patients, 4.5% had never smoked, in contrast to 29.5% of the control group. The average tobacco and alcohol consumption of the patients was approximately twice as high as in the control subjects. The highest alcohol and tobacco consumption was observed in patients suffering from oropharyngeal cancer. Tobacco and alcohol increased the risk of head and neck cancer in a dose-dependent fashion and acted as independent risk factors. In heavy smokers (> 60 pack-years) a relative risk of 23.4 (alcohol adjusted) was calculated. Combined alcohol and tobacco consumption showed a synergistic effect. The risk ratio increased more in a multiplicative than in an additive manner. Oral and laryngeal cancer were associated with the highest tobacco-associated risk values. The highest ethanol-associated risk values were associated with oropharyngeal and laryngeal cancer. The second study was carried out at the ENT Department of the University of Heidelberg on 164 males with squamous cell carcinoma of the larynx and 656 control subjects matched for sex, age and residential area (1:4 matching design). Of the cases, 4.2% had never smoked, compared with 28.5% of the control subjects. The risk of laryngeal cancer by tobacco consumption was dose dependent, reaching a maximum value of 9.1 (adjusted for alcohol) for a consumption of more than 50 tobacco-years (TY). The relative risk of laryngeal cancer associated with alcohol intake was also dose dependent, reaching a value of 9.0 (adjusted for tobacco) for a mean daily consumption of more than 75 g alcohol. An analysis of subsite specific risks showed that heavy smokers (> 50 TY) carried a nearly ten times higher risk of supraglottic cancer than of glottic cancer. The risk of supraglottic cancer from alcohol consumption was also higher than that of glottic cancer.     

Muscle strength and serum testosterone,cortisol and SHBG concentrations in middle-aged and elderly men and women

Forty healthy males (M) and females (F) divided into two different age groups i.e. M50 years (range 44–57; n= 9), F50 years (range 43–54; n= 9), M70 years (range 64–73; n= 11) and F70 years (range 63–73; n= 11) volunteered as subjects for examination of muscle cross-sectional area (CSA) and maximal voluntary isometric force production characteristics of the leg extensor muscles and serum androgen and sex hormone binding globulin (SHBG) concentrations. The CSA in the male groups was greatly larger (P < 0.01) than in the female groups and both elderly groups demonstrated slightly (n.s.) smaller values in the CSA than the two middle-aged groups. Maximal force of 2854 ± 452 N in M50 was greater (P < 0.05) than that of 2627 ± 752 N recorded for F50 as well as the force of 2787 ± 843 in M70 was greater (P < 0.001) than that of 1849 ± 295 recorded for F70. The force between F50 and F70 differed significantly (P < 0.05) from each other. The maximal rate of force production in M50 was greater (P < 0.01) than in F50 as well as in M70 greater (P < 0.001) than in F70. Both middle-aged groups demonstrated greater (P < 0.05) values than the respective elderly groups of the same sex. The individual values in the CSA correlated with the values in maximal force both in the middle-aged subjects (r= 0.66; P < 0.01) and in the elderly subjects (r= 0.69; P < 0.01). The mean concentration of serum testosterone in M50 was slightly (n.s.) greater than in M70 and in F50 significantly (P < 0.05) greater than in F70. Serum SHBG levels were lower in the males (P < 0.01) than in the females and serum testosterone/SHBG ratio in M70 and in F70 were lower (P < 0.05) than in M50 and in F50, respectively. In the females significant positive correlations were observed between the individual values in serum testosterone concentration and the values both in the CSA (r= 0.46; P < 0.05) and in maximal force (r= 0.62; P < 0.01) as well as between serum testosterone/SHBG ratio and both the CSA (r= 0.55; P < 0.05) and maximal force (r= 0.68; P < 0.01). The present results imply that the decreasing basal level of blood testosterone over the years in aging people, especially in females, may lead to decreasing anabolic effects on muscles thus having an association with age-related declines in the maximal voluntary neuromuscular performance capacity in aging people.     

Platelet-activating factor receptor and respiratory and metabolic responses to hypoxia and hypercapnia

Activation of the platelet-activating factor receptor (PAFR) regulates neural transmission. A PAFR blocker reduced the peak hypoxic (pHVR) but not hypercapnic ventilatory (HCVR) responses in rats [Am. J. Physiol. 275 (1998) R604]. To further examine the role of PAFR in respiratory control, genotype-verified PAFR -/- and PAFR +/+ adult male mice underwent hypoxic and hypercapnic challenges. HCVR was similar in the two groups (p-NS). However, pHVR was significantly reduced in PAFR -/- mice (38 +/- 13% baseline [S.D.]) compared to PAFR +/+ mice (78 +/- 16% baseline; P < 0.001, ANOVA), with reduced tidal volume recruitments during pHVR. In addition, hypoxic ventilatory depression was attenuated in PAFR -/- mice (P < 0.01), and was primarily due to attenuation of the time-dependent decreases in oxygen consumption during sustained hypoxia (P < 0.01). Thus, PAFR expression/function modulates components of the acute ventilatory and metabolic adaptations to hypoxia but not to hypercapnia. Imbalances in PAFR activity may lead to maladaptive regulation of the tightly controlled metabolic-ventilatory relationships during hypoxia.