彩色多普勒超声诊断鉴别甲状腺结节内钙化的价值分析

目的评价彩色多普勒超声用于甲状腺结节内钙化鉴别诊断中价值。方法回顾性分析103例甲状腺结节患者术前彩超影像资料、术后手术病理结果评价甲状腺结节钙化类型对鉴别良恶性的结节的临床意义。结果术前经超声诊断甲状腺良性病变符合率为95.24%,恶性结节符合率为82.61%。甲状腺良性病变钙化率为32.50%,恶性结节钙化率13.04%(P0.05);甲状腺良性病变微小钙化率为15.38%,甲状腺恶性结节微小钙化率80.00%(P0.05)。结论彩色多普勒超声可根据结节内钙化回声特点鉴别甲状腺良恶性结节。     

甲状腺癌的超声诊断及相关分子标记物检测的研究进展

随着超声成像技术的发展,甲状腺结节的检出率日益提高,但病灶的良恶性鉴别在声像图上仍缺乏独有的特征性.以结节的常规超声征象为基础,应用甲状腺影像报告和数据系统对结节进行正确分级,有利于甲状腺结节的鉴别诊断.超声造影(CEUS)技术能显示病灶的微血管状态,通过观察不同的增强模式分析甲状腺结节的良恶性;超声弹性成像(UE)技术则通过评价不同组织间的硬度差异,为鉴别甲状腺良恶性结节提供了补充方法;超声引导下细针穿刺抽吸活检(US-FNAB)能准确定位,并为甲状腺结节的术前诊断提供病理依据.对于部分难以明确诊断的穿刺标本进行分子标记物检测则有助于术前诊断甲状腺癌.就甲状腺癌的超声诊断及相关分子标记物检测的研究进展进行综述.     

超声弹性成像联合常规超声在甲状腺结节良恶性鉴别中的诊断价值探究

目的:分析超声弹性成像(Ultrasound Elastography,UE)联合常规超声在甲状腺结节良恶性鉴别诊断中的应用价值.方法:选取本院 60 例甲状腺结节患者作为研究对象,均行常规超声与UE检查,以病理结果为诊断的"金标准",比较常规超声与UE检查单独与联合鉴别恶性甲状腺结节的敏感度、特异度及准确性.结果:常规超声鉴别恶性甲状腺结节的敏感度为 68.75%,特异度为 77.27%,准确性为 75.00%;UE鉴别敏感度为 62.50%,特异度为 81.82%,准确性为76.67%;UE联合常规超声鉴别敏感度 93.75%,特异度 95.45%,准确性 95.00%;常规超声联合UE诊断特异度、准确性明显高于常规超声、UE单一诊断(P＜0.05),诊断敏感度明显高于UE单独应用(P＜0.05).结论:UE联合常规超声可有效提高甲状腺结节良恶性鉴别诊断特异度与准确性.     

CK-19、Tg及HBME-1在甲状腺结节患者中的表达水平及联合检测的临床应用价值

目的 探讨甲状腺结节患者术前及术后血清 Tg 值的变化及CK-19、HBME-1在甲状腺结节组织中的表达和在甲状腺结节鉴别诊断及预后评估方面的价值.方法 选择153名入院手术的甲状腺结节患者,监测其术前 3天内和手术后1月的 Tg值,并且采用免疫组化法检测结节标本中CK-19及HBME-1的表达.结果 Tg、HBME-1、CK-19及HBME-1和CK-19联合表达以恶性结节伴转移最强,恶性无转移较低,甲状腺良性结节最低,在良恶性结节中的差异具有统计学意义.各指标中CK-19的敏感性最高,HBME-1的特异性最高,HBME-1与CK-19联合检测,能提高诊断的准确度.术后Tg值高于或等于术前的患者和术后Tg值低于术前的患者之间复发率差异存在统计学意义.结论 对于甲状腺结节患者,HBME-1、CK-19的表达是具有高度敏感性和特异性的检测指标,联合检测HBME-1和CK-19有利于提高诊断的准确性,对于术前甲状腺结节的良恶性鉴别有重要的参考价值.术前用 Tg 水平来鉴别结节的良恶性意义不大,患者术前术后Tg值的变化是评估近期预后的良好指标,术后Tg值不下降常提示结节预后不良.     

应用超声造影、超声弹性成像鉴别诊断甲状腺小结节的临床价值研究

目的分析应用超声造影、超声弹性成像鉴别诊断甲状腺小结节的临床价值。方法选取116例甲状腺结节患者作为研究对象,比较良恶性甲状腺小结节增强影像特征,分析超声造影、超声弹性成像诊断甲状腺结节的敏感性、特异性及准确性。结果良性甲状腺结节以快进慢出、高增强为主;超声造影诊断甲状腺结节的敏感性、特异性及准确性分别为87.10%、91.86%、89.86%,超声弹性成像诊断甲状腺结节的敏感性、特异性及准确性分别为85.48%、90.70%、88.51%,两组诊断甲状腺结节的敏感性、特异性及准确性比较无差异(P0.05)。两者联合诊断甲状腺结节的敏感性、特异性及准确性分别为96.77%、95.35%、95.85%,其敏感性和准确性显著高于单一的超声造影、超声弹性成像(P0.05)。结论超声造影与超声弹性成像均可有效鉴别诊断良、恶性甲状腺结节,但两者联合诊断敏感性和准确性更高。     

18F-FDG PET/CT在甲状腺结节中的诊断价值

目的 探讨18F-FDG PET/CT在甲状腺良恶性结节中的诊断价值.方法 回顾性分析了48例(男17例,女31例)于本院行18F-FDG PET/CT显像的甲状腺结节患者,所有结节均得到病理证实.利用ROC曲线选取PET/CT半定量指标最大标准摄取值(SUVmax)最佳诊断界值.根据病灶的视觉分级、摄取形态、SUVmax值、CT衰减程度、钙化、突出于甲状腺边界外及病灶边缘是否清晰等七项指标进行综合评分,比较这种综合评分方法与单纯利用SUVmax值判断良恶性的诊断效能,并比较良恶性两组间SUVmax值是否具有差异.最后利用Logistic回归分析七项指标与良恶性结节的相关性.结果 ①SUVmax诊断甲状腺结节的最佳界值为4.71,此时18F-FDG诊断甲状腺恶性病变的灵敏度为80.6％,特异度为75％;②将SUVmax与病理结果对照,发现恶性组SUVmax较良性组明显增高,但恶性组与良性组有重叠;③结合七项指标综合判断结节良恶性的诊断效能较单独利用SUVmax判断良恶性的诊断效能无明显差异(P=0.09);④七项评价指标中SUVmax及CT衰减程度与良恶性相关,对良恶性诊断具有一定价值.结论 ①SUVmax最佳诊断界值为4.71;②良恶性两组间SUVmax差异具有统计学意义;③联合PET及CT多项指标综合诊断不能提高诊断效能;④SUVmax大小及CT中表现为低密度与恶性结节相关,CT中表现为极低密度与良性结节相关,对于良恶性鉴别诊断有一定意义.     

彩色多普勒超声检查在伴有钙化甲状腺结节良、恶性鉴别诊断中的应用

目的:分析彩色多普勒超声检查在伴有钙化甲状腺结节良、恶性鉴别诊断中的应用.方法:回顾性分析自2021年2月至2022年2月本院收治的93例甲状腺结节合并钙化患者的临床资料,分析良、恶性甲状腺结节伴有钙化的超声表现及参数,比较良、恶性结节血流信号及参数.结果:甲状腺良性结节形态规则、边界清晰、连续钙化环出现率均高于恶性结节,周围钙化软组织出现率均低于恶性结节(P<0.05).良性甲状腺结节中血流信号为0级、I级的出现率高于恶性甲状腺结节,Ⅱ级、Ⅲ级的出现率低于恶性甲状腺结节(P<0.05).恶性甲状腺结节收缩期峰值血流速度及阻力指数均高于良性结节,舒张末期血流速度低于良性结节(P<0.05).彩色多普勒超声检查的灵敏度、特异度、准确率分别为91.67％、91.30％、91.40％.结论:彩色多普勒超声检查在伴有钙化甲状腺结节良、恶性鉴别诊断中的应用效果显著,诊断准确率较高.     

计算机辅助诊断软件联合多学科建立甲状腺结节恶性风险预测模型

目的:应用计算机辅助诊断（CAD）软件量化分析甲状腺结节的超声特点,结合临床及实验室指标,建立甲状腺结节恶性风险预测模型,检测预测模型诊断效能并与不同年资医师诊断对比。方法:模型建立组多中心、前瞻性地纳入2019年1月~9月在福建医科大学附属第二医院、厦门大学附属中山医院、漳州市医院接受甲状腺手术及术前超声检查的364例患者（共388个结节）,采用CAD软件分析超声图像。收集CAD软件图像分析信息、临床信息及实验室信息作为相关因素。以病理为金标准,对比21种相关因素的良恶性组间差别,筛选出组间差异具有统计学意义的11种相关因素进行Logistic回归分析,筛选出对结节良恶性预测有统计学意义的6种相关因素进行模型建立。模型验证组纳入同期于3所医院行甲状腺细针穿刺（FNA）及穿刺前检查的105例患者（共105个结节）。由预测模型及3位不同年资的医师分别判断结节良恶性,对照病理结果,绘制受试者工作曲线（ROC）,计算曲线下面积（AUC）、敏感度、特异度、阳性预测值（PPV）、阴性预测值（NPV）,对比预测模型与不同年资医师的诊断效能。结果:建立预测模型为Logit（p）=-5.218+2.601×（低回声指数）+1.981×（强回声指数）+3.079×（边缘模糊指数）+1.267×（纵横比>1）+0.614×（TSH）-0.071×（结节最大径）。计算可得模型的AUC为0.884,敏感度为85.50%,特异度为81.97%,PPV为91.1%,NPV为72.5%。预测模型的AUC、敏感度介于中、高年资医师间,特异度介于低、中年资医师间。结论:该模型具有较好的甲状腺结节恶性风险预测能力,可认为总体诊断效能介于中、高年资医师之间。     

甲状腺结节的超声诊断及超声征象分析

目的 分析甲状腺结节的超声诊断及超声征象特点。方法 回顾性分析2018年3月~2019年3月在我院诊治的50例（62个甲状腺结节）甲状腺结节并行手术治疗的患者临床资料,术前均行超声诊断,比较超声检查与手术病理对结节分型的诊断率、良恶性结节的诊断率、良恶性结节超声诊断指标（边界不清楚、形态不规则、内部回声低、无声晕、有钙化、纵横比≥1）发生率、良恶性结节血流信号分布情况,结果 超声诊断50例,62个甲状腺结节与术后病理结果比较,差异无统计学意义（P＞0.05）;良性（72.58%）和恶性结节（27.41%）超声诊断率分别与术后病理诊断率69.35%、30.64%比较,差异无统计学意义（P＞0.05）, 恶性结节超声诊断指标边界不清楚、形态不规则、内部回声低、无声晕、有钙化、纵横比≥1发生率与良性结节比较,差异有统计学意义（P＜0.05）;甲状腺良性结节血流信号分布少于恶性结节,差异有统计学意义（P＜0.05）。结论 超声诊断甲状腺结节准确率高,对患者无创伤、操作简单,且可显示良恶性结节超声征象特点,为良恶性鉴别诊断提供可靠的参考依据,具有重要的临床应用价值。     

TI-RADS分级联合SPECT诊断甲状腺良恶性结节的价值分析

目的:分析甲状腺影像报告和数据系统(Thyroid Imaging Reporting and Data System,TI-RADS)分级联合单光子发射计算机断层成像术(Single-photon Emission Computed Tomography,SPECT)对甲状腺良恶性结节的诊断价值.方法:选取 2021 年 1 月至 2022 年 12 月我院 82 例甲状腺结节患者,分析TI-RADS分级、SPECT诊断及联合诊断结果,并对甲状腺结节良恶性的诊断价值采用受试者工作特征(Receiver Operating Characteristic,ROC)曲线进行分析.结果:TI-RADS分级联合SPECT诊断结果中良、恶性结节分别为 58 个、24 个.TI-RADS分级联合SPECT对甲状腺良恶性结节诊断的灵敏度、特异性、准确度高于TI-RADS分级和SPEC单独诊断(P＜0.05).TI-RADS分级联合SPECT诊断甲状腺良恶性结节的曲线下面积(Area Underthe Curve,AUC)最大为0.849.结论:TI-RADS分级联合SPECT能够提高对甲状腺良恶性结节的诊断效能和准确率.     

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.