住院高血压病人伴发抑郁症状的危险因素分析

目的旨在分析住院高血压病人出现抑郁症状的相关危险因素。方法选择在我院住院的高血压病人141例,使用病人健康问卷-9(PHQ-9)对病人抑郁状态进行评估。比较抑郁组与非抑郁组的一般情况及生化指标,并采用多因素Logistic回归分析相关危险因素。结果住院高血压病人共141例,其中存在抑郁症状的共40例,占28.4%。抑郁组与非抑郁组相比,年龄、发病年龄、高血压病程、独居与否、是否并发脑血管疾病差异有统计学意义(P0.05);叶酸、Hcy、ALT、白蛋白(ALB)水平差异有统计学意义(P0.05)。住院高血压病人伴发抑郁症状的危险因素为:年龄(OR=1.069,95%CI:1.007～1.135)、叶酸水平降低(OR=0.730,95%CI:0.607～0.877)、Hcy水平升高(OR=1.088,95%CI:1.001～1.184)。结论年龄、叶酸水平降低及血清Hcy水平升高是住院高血压病人出现抑郁症状的危险因素。     

预测高血压合并冠心病PCI术后支架内再狭窄nomogram模型的建立与验证

[目的]分析高血压合并冠心病经皮冠状动脉介入治疗(PCI)术后支架内再狭窄(ISR)的危险因素,并构建nomogram预警模型。[方法]选取阜阳市第二人民医院2020年6月—2022年3月收治的182例高血压合并冠心病PCI术后患者作为研究对象,根据术后是否发生ISR将其分为ISR组(n=42)和非ISR组(n=140)。分析所选患者的临床资料,采用单因素分析、LASSO和Logistic回归分析筛选高血压合并冠心病PCI术后发生ISR的危险因素,根据危险因素构建nomogram预警模型并进行拟合优度检验。[结果]本研究共纳入182例高血压合并冠心病PCI术后患者,发生ISR有42例,发生率为23.08%;单因素分析、LASSO回归分析显示,两组糖尿病、长期吸烟、支架直径、支架长度、高尿酸、高敏C反应蛋白(hs-CRP)、血清淀粉样蛋白A(SAA)及脂蛋白(a)水平差异有统计学意义(P<0.05)。Logistic回归分析显示,糖尿病(OR=4.464,95%CI:1.733～11.498,P=0.002)、长期吸烟(OR=4.648,95%CI:1.812～11.921,P=0...     

心衰合并房颤的老年患者1年内再住院风险因素分析及预测模型的建立

目的 探索心衰合并房颤的老年患者1年内再住院进行治疗的风险因素，并构建风险预测模型。方法 回顾性分析2018年1月—2022年1月在复旦大学附属华东医院治疗的129例老年房颤合并心衰患者的临床资料，依据1年内有无再次住院分为未再住院组(n=72)和再住院组(n=57)。采用单因素、多因素回归分析法分析2组患者的临床、实验室及影像学指标值，筛选出心衰合并房颤的老年患者再住院的独立危险因素。根据筛选结果，构建综合的诺莫图风险预测模型，计算不同单一模型及综合模型的诊断效能，通过ROC曲线和曲线下面积进行风险因素评估。结果 根据单因素、多因素逻辑回归模型筛选显示，BMI(OR=1.419, 95%CI:1.165～1.729,P=0.001)、出院后服药依从性(OR=4.604, 95%CI:1.165～19.484,P=0.038)、高血压(OR=3.380, 95%CI:1.230～9.290,P=0.018)和NT-proBNP(OR=2.956, 95%CI:1.781～5.085,P<0.001)为心衰合并房颤的老年患者1年内再住院的独立危险因素。其中NT-proBNP和BMI...     

高龄原发性高血压患者合并慢性肾脏病的危险因素

目的了解80岁以上原发性高血压(EH)住院患者合并慢性肾脏病(CKD)的情况,分析相关危险因素。方法选取南京医科大学第二附属医院心血管内科住院的1 555例65岁以上EH患者,依据是否≥80岁分为2组:高龄组(n=575)和非高龄组(n=980)。收集患者的临床资料。采用SPSS 22.0软件进行数据处理,logistic回归分析EH合并CKD的危险因素。结果与非高龄EH组患者比较,高龄EH组患者CKD发生率显著升高(52.9%vs 29.5%,P0.05)。高龄EH患者合并CKD的危险因素依次为高尿酸血症(OR=2.514,95%CI 1.750～3.611; P 0.001)、年龄(OR=1.072,95%CI1.018～1.129;P=0.009)和收缩压(OR=1.019,95%CI 1.011～1.028; P 0.001),保护因素为高密度脂蛋白胆固醇(OR=0.516,95%CI 0.315～0.847;P=0.009);非高龄老年EH患者合并CKD的危险因素依次为高尿酸血症(OR=2.729,95%CI 1.991～3.740;P0.001)、糖尿病(OR=1.944,95%CI 1.420～2.662;P0.001)、年龄(OR=1.140,95%CI 1.101～1.182;P0.001)和收缩压(OR=1.009,95%CI 1.003～1.016; P=0.007),保护因素为高密度脂蛋白胆固醇(OR=0.448,95%CI0.278～0.722;P=0.001)。结论高龄老年EH患者合并CKD的比例显著高于非高龄老年EH患者,高龄EH患者合并CKD与高尿酸血症、年龄、收缩压及高密度脂蛋白胆固醇水平有关。     

高血压病患者发生心房颤动的相关危险因素临床分析

目的:探讨高血压病患者发生心房颤动(AF)的临床相关危险因素。方法:将423例高血压病患者分为高血压病合并AF(n=233),不合并AF(n=190)两组,回顾性分析比较两组患者的临床资料,并进行Logistic回归分析高血压病患者发生AF的可能危险因素。结果:单变量分析显示,与非AF组相比,AF组的年龄较大(P<0.001)、体重指数偏高(P=0.019),心脏超声测量左心房内径、左室舒张末期内径和左室收缩末期内径均偏大(P<0.001),左室射血分数(P=0.005)较低。肌酐(P<0.001)和尿酸水平(P=0.013)偏高,但总胆固醇及低密度脂蛋白胆固醇水平(P<0.001)较低。Logistic多因素回归分析提示,年龄(OR=1.08,95%CI:1.04～1.13,)、左心房内径(OR=1.51,95%CI:1.38～1.63)、低密度脂蛋白胆固醇含量(OR=0.52,95%CI:0.36～0.78)与高血压病患者发生AF存在显著的关联关系。结论:年龄及左心房内径越大、低密度脂蛋白胆固醇水平越低的高血压病患者发生AF的危险性高。     

肝性脑病患者短期预后的相关危险因素分析

目的探讨肝性脑病(HE)患者短期预后相关的危险因素。方法回顾性分析2013年1月-2015年12月于吉林大学第一医院住院治疗的316例HE患者的临床资料,根据预后分为生存组(n=229)与死亡组(n=87)。将患者基础资料及生化指标进行单因素及多因素分析,筛选影响HE预后的危险因素。计量资料2组间比较采用t检验或Mann-Whitney U检验,计数资料2组间比较采用χ~2检验。将单因素分析中有统计学意义的变量进一步行多因素logistic回归分析。结果 316例患者的男女比例为1.72∶1,45岁及以上患者269例(85.13%)。单因素分析结果显示年龄、合并原发性肝癌、HE分期、WBC、中性粒细胞、Hb、PLT、国际标准化比值、PT、PTA、尿素氮、肌酐、血清钠、血清钾、ALT、AST、GGT、Alb、IBil、TBil、前白蛋白在2组之间差异均有统计学意义(P值均0.05)。多因素logistic回归分析结果显示合并原发性肝癌[比值比(OR)=3.278,95%可信区间(95%CI):1.494~7.194,P=0.003]、HE分期(OR=2.402,95%CI:1.711~3.372,P0.001)、PTA(OR=0.969,95%CI:0.951~0.988,P=0.001)、血清钠(OR=0.956,95%CI:0.922~0.992,P=0.018)、TBil(OR=1.004,95%CI:1.003~1.006,P0.001)是影响HE患者预后的独立危险因素。结论合并原发性肝癌、HE高分期、低血钠、PTA降低、TBil升高是影响HE预后的独立危险因素,据此建立的方程对临床有一定参考价值。     

糖尿病视网膜病变合并糖尿病肾病的危险因素及其预测价值

目的探讨糖尿病视网膜病变(DR)合并糖尿病肾病(DN)的危险因素及预测价值。方法回顾性分析2017年5月至2018年5月南京医科大学附属无锡市人民医院内分泌科收治的2型糖尿病(T2DM)患者1 969例,其中糖尿病视网膜病变(DR)合并糖尿病肾病(DN)患者609例,单纯DR患者746例,未并发DN和DR患者614例,比较3组患者的血糖、血压、肝功能和肾功能指标水平,分析DR合并DN的危险因素及预测价值。采用SPSS 18.0统计软件对数据进行分析。组间比较采用单因素方差分析或χ~2检验。多因素logistic回归分析DR合并DN的危险因素。受试者工作特征(ROC)曲线分析因素预测DR合并DN的价值。结果除高密度脂蛋白胆固醇(HDL-C)水平和左侧颈动脉内膜中层厚度(IMT)外,3组患者其余指标差异均具有统计学意义(P0.05)。多因素logistic回归分析结果显示年龄(OR=0.966,95%CI 0.932～1.000; P=0.049)、白蛋白(ALB)(OR=0.872,95%CI 0.837～0.908; P0.001)、服用他汀类药物(OR=0.400,95%CI 0.265～0.606; P0.001)是DR合并DN的保护因素,高血压病程(OR=1.021,95%CI 1.005～1.037; P=0.011)、收缩压(OR=1.018,95%CI 1.007～1.029; P=0.002)、空腹血糖(OR=1.054,95%CI 1.002～1.108; P=0.040)、甘油三酯(OR=1.133,95%CI 1.021～1.256;P=0.019)、低密度脂蛋白胆固醇(OR=1.355,95%CI 1.017～1.805; P=0.038)、血尿酸(OR=1.124,95%CI 1.016～1.244;P=0.023)、胱抑素C(OR=2.466,95%CI 1.495～4.068; P0.001)、眼底评分(OR=1.275,95%CI 1.088～1.494; P=0.003)、左室后壁厚度(OR=1.306,95%CI 1.051～1.622; P=0.016)和颈动脉粥样斑块形成(OR=1.578,95%CI 1.051～2.370;P=0.028)为危险因素。ROC曲线分析结果表明胱抑素C预测DR合并DN价值最高,AUC为0.677。结论 T2DM患者DR合并DN的患病率较高,其发生与多种因素相关,其中,胱抑素C预测DR合并DN价值最高。     

老年COPD患者合并支气管扩张的临床特征及危险因素

目的探讨老年慢性阻塞性肺疾病(COPD)患者合并支气管扩张的临床特征及危险因素。方法回顾性分析310例老年COPD患者资料。根据胸部高分辨CT是否合并支气管扩张,分为COPD组(194例)、COPD合并支扩组(116例)。搜集病例资料,采用单因素、多因素Logistic回归模型分析COPD合并支气管扩张的危险因素。结果单因素结果显示,与COPD组相比,COPD合并支扩组气流受限严重、痰细菌分离率高、炎症反应重、体重指数(BMI)低、既往肺结核发生率及1年内曾有急性加重发生率高,差异均有统计学意义(P0.05;P0.001)。多因素Logistic回归显示,BMI18.5 kg/m~2(OR=3.569,95%CI:1.842～6.915,P0.001)、中重度气流受限(中度:OR=3.045,95%CI:1.235～7.511,P=0.016;重度:OR=3.988,95%CI:1.577～10.084,P=0.003)是COPD合并支气管扩张的危险因素。与柱状、囊柱状相比,囊状支气管扩张铜绿假单胞菌分离率高、气流受限严重,差异均有统计学意义(均P0.05)。结论 BMI18.5 kg/m~2和中重度气流受限是老年COPD患者合并支气管扩张的高危因素。     

奈韦拉平治疗获得性免疫缺陷综合征导致肝损伤的危险因素分析

目的分析获得性免疫缺陷综合征患者使用包含奈韦拉平(NVP)方案进行联合抗反转录病毒治疗(c-ART)引起超敏反应肝损伤的相关危险因素。方法收集2008年6月-2015年10月武汉大学中南医院接受包含NVP联合治疗方案的患者临床资料及血液标本共132例,采用PCR-SSP技术检测人类白细胞抗原(HLA)DRB1及HLA-Cw基因型。开始c-ART治疗6周内出现NVP超敏反应相关肝损伤者列为肝损伤组(n=41),未发生肝损伤者为对照组(n=91),分析NVP超敏反应引起肝损伤的相关危险因素。计量资料组间比较采用t检验;计数资料组间比较采用χ~2检验。采用单因素Logistic回归法分析NVP超敏反应相关肝损伤的危险因素,将P0.10的单因素分析变量纳入多因素Logistic回归模型进行逐步回归分析。用Spearman相关系数分析发生超敏反应相关肝损患者中CD4细胞数与ALT值的相关性。结果多因素Logistic回归分析显示男性[P=0.002,比值比(OR)=12.297,95%可信区间(95%CI):2.467~61.300]、基线CD4细胞计数高(P=0.023,OR=1.010,95%CI:1.001~1.018)、合并HCV感染(P=0.022,OR=10.598,95%CI:1.411~79.613)、HLA-Cw*03基因携带(P0.001,OR=34.119,95%CI:5.543~210.023)为NVP超敏反应相关肝损伤的危险因素。在合并HCV感染或高CD4细胞数(≥200个/μl)或携带HLA-Cw*03等位基因患者中男性肝损伤发生率(63.9%)高于女性(11.6%),差异有统计学意义(χ~2=23.390,P0.001)。患者基线CD4细胞计数与ALT水平呈正相关(r=0.583,P0.001)。结论男性、合并HCV感染、基线CD4细胞数高的人类免疫缺陷病毒感染者应尽量避免使用NVP,HLA-CW*03基因筛查对于预测NVP超敏反应相关肝毒性的价值有待进一步研究。     

缺血性结肠炎危险因素的病例-对照研究

目的总结分析缺血性结肠炎发病的危险因素,提高对该病的认识,以助于早期诊断,改善预后。方法采用回顾性病例对照研究,选取2000~2011年于北京大学第三医院消化内科住院的缺血性结肠炎患者158例作为病例组,选择同期入院、性别年龄相匹配的158例大肠息肉患者作为对照组,进行1:1病例对照研究。先采用单因素分析筛选出两组间具有统计学差异的指标,再进行多因素Logistic回归分析,以发现缺血性结肠炎发病的独立危险因素。结果单因素分析发现,病例组与对照组具有统计学差异的指标包括:糖尿病(P=0.005)、脑血管病(P=0.047)、脂肪肝(P=0.012)、腹部手术史(P0.001)。多因素Logistic回归分析发现,缺血性结肠炎的独立危险因素包括腹部手术史(OR=3.037;95%CI 1.70-5.43)、糖尿病(OR=2.55;95%CI 1.24-5.24)、脂肪肝(OR=2.143;95%CI 1.09-4.21)、脑血管病(OR=2.088;95%CI 1.04-4.20)。结论腹部手术史、糖尿病、脂肪肝、脑血管病为缺血性结肠炎发病的危险因素。     

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of ‘energy flow’ between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called ‘death.’ This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.     

Unusual responses of nocturnal pineal melatonin synthesis and secretion to swimming: Attempts to define mechanisms

Abstract: The effect of swimming at night on rat pineal melatonin synthesis was compared with that of light exposure at night. Rats were forced to swim at 0030 hr (lights out at 2000 hr) and sacrificed by decapitation 15 and 30 min later, immediately after swimming. Other groups of animals were exposed to white light (650μW/cm²) for 15 and 30 min at same time. Swimming caused a rapid and highly significant drop in the melatonin content in the pineal gland; however, the activity of N-acetyltransferase (NAT), the supposed rate limiting enzyme in the melatonin production, was not changed. Despite the drop in pineal melatonin levels, serum concentrations of the indole remained elevated in the rats that swam. In contrast, melatonin levels in the pineal and serum of light exposed rats fell precipitously, accompanied by a significant suppression of NAT activity. Since we anticipated that the strenuous exercise associated with swimming may induce release of artrial natriuretic peptide (ANP) from the heart, which in turn could cause the release of pineal melatonin, in a second study we injected physiological saline intravenously to stretch the cardiac muscle and release ANP. Three milliliters of normal saline was injected during the day into the jugular vein of anesthetized rats that were pretreated with isoproterenol to stimulate pineal melatonin production. Animals were killed 15 min after the saline injection, and pineal NAT activity and pineal melatonin levels were measured. The saline injections caused no alteration in the elevated levels of either NAT or melatonin. These data suggest that the disparity in pineal NAT activity (which was high) and pineal melatonin (which was low), in animals swum at night, may not be caused by ANP which is released during strenuous exercise such as swimming.     

Melatonin and photoperiodic time measurement: Seasonal breeding in the sheep

Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.     

Serological survey of HIV and syphilis in pregnant women in Madagascar

Objectives Peripartal transmission of human immunodeficiency virus (HIV) and Treponema pallidum, the causative agent of syphilis, leads to severe consequences for newborns. Preventive measures require awareness of the maternal infection. Although HIV and syphilis testing in Madagascar could be theoretically carried out within the framework of the national pregnancy follow‐up scheme, the required test kits are rarely available at peripheral health centres. In this study, we screened blood samples of pregnant Madagascan women for HIV and syphilis seroprevalence to estimate the demand for systemic screening in pregnancy. Methods Retrospective anonymous serological analysis for HIV and syphilis was performed in plasma samples from 1232 pregnant women that were taken between May and July 2010 in Ambositra, Ifanadiana, Manakara, Mananjary, Moramanga and Tsiroanomandidy (Madagascar) during pregnancy follow‐up. Screening was based on Treponema pallidum haemagglutination tests for syphilis and rapid tests for HIV, with confirmation of positive screening results on line assays. Results Out of 1232 pregnant women, none were seropositive for HIV and 37 (3%) were seropositive for Treponema pallidum. Conclusions Our findings are in line with previous studies that describe considerable syphilis prevalence in the rural Madagascan population. The results suggest a need for screening to prevent peripartal Treponema pallidum transmission, while HIV is still rare. If they are known, Treponema pallidum infections can be easily, safely and inexpensively treated even in pregnancy to reduce the risk of transmission.     

Variabilité des concentrations plasmatiques de l’angiotensinogène et risque d’hypertension artérielle chez le rat transgénique

Aim

Genetic polymorphisms of the human angiotensinogen gene are frequent and may induce up to 30% increase of plasma angiotensinogen concentrations with a blood pressure increase of up to 5 mmHg. Their role for the pathogenesis of human arterial hypertension remains unclear. High plasma angiotensinogen levels could increase the sensitivity to other blood pressure stressors.

Methods

Male transgenic rats with a 9-fold increase of plasma angiotensinogen concentrations and male non-transgenic rats aged 10 weeks were treated or not with NG-Nitro-L-arginine-methyl ester for 3 weeks in their drinking water (n = 3/group). Systolic blood pressure and body weight were measured at baseline and at the end of the study when left ventricular weight and ventricular expression of angiotensin I-converting enzyme and procollagen Iα1 were determined (polymerase chain reaction).

Results

At baseline, transgenic rats had +18 mmHg higher bood pressure and –8% lower body weight compared to non-transgenic rats (P < 0.05) without significant changes for the vehicle groups throughout the study (P > 0.05). NG-Nitro-L-arginine-methyl ester increased blood pressure, left ventricular weight and left ventricular weight indexed for body weight by +41%, +17.6% and +18.6% (P < 0.05) in transgenic and +25%, +5.3% and +6.7% (P > 0.05) in non-transgenic rats compared to untreated animals, respectively. Cardiac gene expression showed no differences between groups (P > 0.05).

Conclusion

Increased plasma angiotensinogen levels may sensitize to additional blood pressure stressors. Our preliminary results point towards an independent role of angiotensinogen in the pathogenesis of human hypertension and associated end-organ damage.     

Morphological and immunocytochemical heterogeneity of cultured pinealocytes from one-week-and two-month-old rats: Planimetric and densitometric investigations

Abstract: In vitro preparations of rat pinealocytes are widely used for biochemical analyses of signal transduction processes. This paper deals with morphological and immunocytochemical features of such preparations. Special attention was paid to the problems of whether pinealocytes represent a heterogeneous cell population and how such heterogeneity may develop during ontogeny. The investigations were performed with cells which were obtained from the pineal organ of one-week-and two-month-old rats, attached to synthetic peptide-coated coverslips or tissue culture chamber slides, and maintained under in vitro conditions overnight. The attached cells were then fixed with paraformaldehyde. These preparations yielded monolayers of spherical cells of different sizes; most cells were isolated, but some of them were aggregated and formed small clusters. On the average, the cells from the one-week-old animals were smaller than the cells from the two-month-old animals. Immunocytochemical demonstration of S-antigen, a pinealocyte-specific marker, showed that the majority of the cells from two-month-old animals were intensely or moderately labelled. Pinealocytes from one-week-old animals were less S-antigen immunoreactive. Only very few cells (less than 1% displayed glial fibrillary acidic protein (GFAP)-immunoreactivity. Planimetric investigations of the cell size and semiquantitative densitometric investigations of the intensity of the S-antigen immunoreaction revealed that (i) pinealocytes kept in vitro form a heterogeneous cell population, and that (ii) this heterogeneity increases during postnatal development from one-week-old to two-month-old animals. Two groups of pinealocytes can be distinguished based on their developmental fate: pinealocytes of one group grow dramatically, but show only a moderate increase in S-antigen immunoreactivity, and pinealocytes of the other group retain their size, but display a distinct increment in S-antigen immunoreacti vitv.     

MUTATION FREQUENCY IN NURSES AND PHARMACISTS WORKING WITH CYTOTOXIC DRUGS

Individuals occupationally exposed to cytotoxic drugs may be at risk owing to the effects of these agents on DNA. As an index of DNA damage, in vivo mutations were measured in lymphocytes from 24 oncology nurses or pharmacists and 24 matched controls. Mutation frequency was significantly increased in exposed individuals and appeared to be related to duration of exposure. However, the overall magnitude of the increase was small and its biological significance remains to be determined.