ERK1/2MAPK通路在Eca109细胞体外增殖和迁移中的作用及其机制

目的观察ERK1/2 MAPK通路在食管鳞状细胞癌(ESCC)Eca109细胞系增殖和迁移中的作用并探讨其作用机制。方法使用MAPK(ERK1/2)抑制剂U0126处理Eca109细胞;细胞计数检测细胞增殖;倒置显微镜下观察细胞形态;实时荧光定量PCR(qRT-PCR)检测ERK1/2 mRNA;Western blot检测总ERK1/2(t-ERK1/2)和磷酸化ERK1/2(p-ERK1/2);MTT和细胞划痕实验检测细胞增殖和迁移能力;qRT-PCR检测MicroRNA-21(miR-21)。结果20μmol/L浓度的U0126可抑制Eca109细胞生长(P<0.05),破坏细胞正常形态,ERK1/2 MAPK通路的活化在蛋白质水平被抑制(P<0.05),Eca109细胞增殖和迁移明显减弱(P<0.05),显著下调miR-21的表达(P<0.05)。结论ERK1/2 MAPK信号通路抑制可减弱Eca109细胞增殖和迁移,其可能的作用机制之一与其抑制miR-21表达有关。     

P53和1d2蛋白在食管鳞状细胞癌的表达及其意义

目的研究P53、Id2蛋白在食管鳞状细胞癌组织的表达及其意义。方法采用免疫组织化学SP法和图像分析技术检测122例食管鳞状细胞癌及90例癌旁正常组织中P53、Id2的表达情况。结果122例食管鳞状细胞癌中P53、Id2表达水平均高于癌旁正常组织（P〈0．01）。P53表达强度与患者的性别、年龄及肿瘤的分化程度未见明显相关性（P〉0．05）,但与肿瘤的浸润深度及淋巴结转移情况相关（P〈0．05）;Id2的表达与患者的性别、年龄及淋巴结转移情况未见明显相关性（P〉0．05）,但与肿瘤的分化程度成负相关（P〈0．05）,且与肿瘤浸润深度正相关（P〈0．05）。结论P53、Id2在食管鳞状细胞癌的高表达可能作为判断食管鳞状细胞癌生物学行为的潜在指标。     

miR-206、PTP1B在食管鳞癌组织中的表达及与预后的关系

目的 检测食管鳞癌(ESCC)患者癌组织中微小RNA-206(miR-206)、蛋白酪氨酸磷酸酶1B(PTP1B)表达情况,并探讨二者与临床病理特征及预后的关系.方法 选取2013年6月至2016年2月本院收治的80例ESCC患者癌组织为ESCC组,另选取距癌组织边缘>5 cm的对应癌旁组织标本为对照组.采用实时荧光定量PCR测定miR-206、PTP1B mRNA表达水平;采用免疫组织化学法测定PTP1B蛋白表达情况;分析miR-206、PTP1B蛋白表达与临床病理特征及ESCC患者预后的关系;COX法分析影响ESCC患者预后的因素.结果 与对照组比较,ESCC组癌组织中miR-206水平显著降低(P<0.05),PTP1B mRNA水平、PTP1B蛋白阳性表达率显著升高(P<0.05).ESCC患者癌组织miR-206、PTP1B mRNA表达呈负相关(P<0.05).miR-206、PTP1B蛋白表达与ESCC患者TNM分期、组织分化程度、淋巴结转移有关(P<0.05),与年龄、肿瘤大小、肿瘤位置、浸润程度无关(P>0.05).miR-206低表达患者5年生存率12.20％(5/41)显著低于miR-206高表达患者77.14％(27/35)(P<0.05),PTP1B蛋白阳性患者5年生存率29.31％(17/58)显著低于PTP1B蛋白阴性患者83.33％(15/18)(P<0.05).TNM分期为Ⅲ+Ⅳ期、低分化程度、淋巴结发生转移、miR-206低表达、PTP1B蛋白阳性均是影响ESCC患者预后的危险因素(P<0.05).结论 miR-206低表达、PTP1B蛋白阳性表达可能与ESCC发生发展有关,且可一定程度评估患者预后,对指导临床治疗方面有一定参考意义.     

食管鳞状细胞癌中FBXO32基因表达及其临床意义

目的观察食管鳞状细胞癌(esophageal squamous cell carcinoma,ESCC)中FBXO32基因的表达,探讨该基因在ESCC发生、发展中的作用。方法分别应用RT-PCR及免疫组织/细胞化学法检测食管癌细胞和ESCC组织中FBXO32 mRNA及蛋白表达,观察DNA去甲基化剂5-氮杂-2’-脱氧胞苷(5-aza-2’-deoxycitydine,5-aza-dC)对食管癌细胞系(TE1、TE13、T.TN、Yes-2)FBXO32基因表达的影响。结果 TE13、T.TN、Yes-2细胞株中均未检测到FBXO32 mRNA及蛋白表达,在去甲基化剂作用后,4株食管癌细胞株中FBXO32基因表达均上调。FBXO32 mRNA在ESCC和癌旁正常组织中的表达量分别为0.24±0.15和0.49±0.21,ESCC组织中FBXO32 mRNA表达量明显低于癌旁正常组织(P<0.05),且与患者的淋巴结转移及肿瘤组织的分化程度密切相关。51例ESCC组织中,12例FBXO32基因蛋白表达,阳性率为23.5%,明显低于正常食管黏膜组织(70.5%,P<0.01),且FBXO32与患者的淋巴结转移密切相关。结论 FBXO32基因在ESCC中的异常低表达与ESCC的发生、发展密切相关,且甲基化可能是其表达沉默的机制之一。     

食管鳞状细胞癌组织中RASSF1A、LSD1的表达及其与预后的关系

目的探讨RASSF1A和LSD1在食管鳞状细胞癌(esophageal squamous cell carcinoma,ESCC)组织中的表达及其与预后的关系。方法采用免疫组化SP法,检测RASSF1A和LSD1在80例ESCC组织及其癌旁正常组织中的表达。结果 ESCC组织中RASSF1A阳性率低于正常组织,LSD1阳性率高于正常组织(P均0.05)。RASSF1A阳性与ESCC的TNM分期、分化程度、浸润深度、淋巴结转移及肿瘤大小有关(P0.05);LSD1阳性与ESCC淋巴结转移及肿瘤大小有关(P0.05)。RASSF1A阳性患者的生存时间高于阴性患者(P0.05);LSD1阳性患者的生存时间明显低于阴性患者(P0.05)。TNM分期、浸润程度、肿瘤大小均可作为ESCC独立的预后风险因素。结论 RASSF1A、LSD1在ESCC的发生、发展中表达异常,其与患者的肿瘤进展、转移及预后有关,结合临床病理可作为判断预后的指标。     

食管鳞状细胞癌中PTPN6的表达及与临床病理特征的关系

目的检测食管鳞状细胞癌(esophageal squamous cell carcinoma,ESCC)中非受体型PTPN6基因的表达,探讨其与ESCC临床病理特征及预后的关系。方法采用RT-qPCR法检测食管癌细胞和71例ESCC及癌旁正常组织中PTPN6基因mRNA的表达;应用Western blot法和免疫组化SP法检测食管癌细胞和ESCC及癌旁正常组织中PTPN6蛋白的表达;按ESCC组织中PTPN6的蛋白表达分为阳性组和阴性组,行Kaplan-Meier生存曲线分析,并通过Cox风险比例模型对其他变量进行校正。结果与正常食管上皮细胞相比,PTPN6 mRNA和蛋白在食管癌细胞中表达下调(P 0.05); ESCC组织中PTPN6 mRNA相对表达量显著低于癌旁正常组织[(1.000±0.001) vs (1.815±0.386),t=13.533,P 0.05]; PTPN6 mRNA表达与患者TNM分期、病理分级及淋巴结转移有关(P 0.05)。ESCC中PTPN6的阳性率为32.4%(23/71),明显低于癌旁组织(P 0.05); PTPN6蛋白表达与患者TNM分期、病理分级及淋巴结转移密切相关(P 0.05)。Kaplan-Meier结果显示,PTPN6低表达与患者生存时间有关(P 0.05)。多变量Cox模型校正后,PTPN6蛋白表达对患者预后有影响(OR=2.694,P 0.05)。结论 PTPN6基因在食管癌细胞系及ESCC组织中表达沉默,其与食管癌的发生、发展密切相关,有望成为ESCC患者预后评估的指标。     

食管鳞状细胞癌中RNF113A的表达及临床病理意义

目的 探讨环指蛋白113A(ring finger protein 113A,RNF113A)在食管鳞状细胞癌(esophageal squamous cell carcinoma, ESCC)组织中的表达及临床病理意义。方法 采用免疫组化SP法检测100例ESCC组织及80例配对癌旁组织芯片中RNF113A的表达。结果 与癌旁正常组织相比，ESCC组织中RNF113A的表达上调，差异有统计学意义(P<0.05)。RNF113A表达与ESCC临床分期(P<0.009)、T分期(P=0.015)相关。Kaplan-Meier生存曲线提示，RNF113A表达与ESCC预后无关(P>0.05)。单因素分析结果显示，患者性别、临床分期、T分期、淋巴结转移及组织学类型影响ESCC患者的总生存期。多因素分析结果显示，肿瘤临床分期、淋巴结转移及组织学类型是ESCC预后的独立危险因素。结论 RNF113A在ESCC组织中高表达，且RNF113A表达程度越高，临床分期及T分期越晚；在RNF113A阳性ESCC中，男性、临床分期及T分期越晚、淋巴结转移阳性的患者术后生存率低，预后差。     

食管鳞状细胞癌组织中Periostin、VEGF的表达及意义

目的：探讨Periostin、VEGF蛋白在食管鳞状细胞癌组织中的表达及意义。方法采用免疫组化SP法检测130例食管鳞状细胞癌组织及癌旁正常食管黏膜组织中Periostin、VEGF蛋白的表达。结果食管鳞状细胞癌组织中Periostin和VEGF的阳性率明显高于正常食管黏膜组织(P<0．05)。 Periostin表达与食管鳞状细胞癌浸润深度、淋巴结转移有显著相关性(P<0．05)。 VEGF表达与食管鳞状细胞癌分化程度、浸润深度和淋巴结转移有显著相关性(P<0．05)。 Periostin与VEGF表达呈正相关(P<0．05),66例食管鳞状细胞癌患者获得临床随访资料,随访时间1~48个月,Kaplan-Meier生存曲线分析显示,Peri-ostin阳性组患者的生存率明显低于 Periostin阴性组( P<0．05), VEGF阳性组患者的生存率明显低于 VEGF 阴性组( P <0．05)。结论 Periostin与VEGF表达密切相关,联合检测Periostin、VEGF可作为判定食管鳞状细胞癌侵袭、转移能力的客观指标,对食管鳞状细胞癌的预后判断具有重要意义。     

P53和Id2蛋白在食管鳞状细胞癌的表达及其意义

目的研究P53、Id2蛋白在食管鳞状细胞癌组织的表达及其意义。方法采用免疫组织化学SP法和图像分析技术检测122例食管鳞状细胞癌及90例癌旁正常组织中P53、Id2的表达情况。结果 122例食管鳞状细胞癌中P53、Id2表达水平均高于癌旁正常组织(p0.01)。P53表达强度与患者的性别、年龄及肿瘤的分化程度未见明显相关性(p0.05),但与肿瘤的浸润深度及淋巴结转移情况相关(p0.05);Id2的表达与患者的性别、年龄及淋巴结转移情况未见明显相关性(p0.05),但与肿瘤的分化程度成负相关(p0.05),且与肿瘤浸润深度正相关(p0.05)。结论 P53、Id2在食管鳞状细胞癌的高表达可能作为判断食管鳞状细胞癌生物学行为的潜在指标。     

食管鳞状细胞癌组织中Id1和Id2的表达及其意义

目的研究Id1、Id2在食管鳞状细胞癌中的表达及其意义。方法采用免疫组织化学SP法和图像分析技术检测122例食管鳞状细胞癌及90例癌旁正常组织中Id1、Id2的表达情况。结果122例食管鳞状细胞癌中Id1、Id2表达高于癌旁正常组织(P0.01);Id1、Id2表达强度与患者的性别、年龄、淋巴结转移未见明显相关性(P0.05);Id1表达高分化与低分化组差异有显著性(P0.05);Id2的表达与肿瘤的分化程度成负相关(P0.05),且与肿瘤浸润深度正相关(P0.05)。结论Id1、Id2的高表达可能是食管鳞状细胞癌一个重要的分子学改变,Id2可作为判断食管鳞状细胞癌生物学行为的潜在指标。     

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.