Blood pressure and muscle sympathetic nerve activity during cold pressor stress: fitness and gender

We examined putative autonomic and hemodynamic mechanisms that might explain our prior finding that cardiorespiratory fitness mitigates blood pressure responses by normotensive women during the hand cold pressor test. We report that fitness level was inversely related to increases in systolic and diastolic blood pressures and muscle sympathetic nerve activity (MSNA) during the cold pressor among women but not men. The pattern of responses among fitter women was consistent with decreased central sympathetic outflow resulting in reduced stroke volume or dampened peripheral resistance in vascular beds other than calf skeletal muscle. Fitter men and women had slightly larger increases in blood pressure during mental arithmetic, but otherwise fitness was not directly related to stress responses. The results further encourage consideration of cardiorespiratory fitness as a modifying covariate when the hand cold pressor test is used as a predictor of future hypertension among women.     

Saethre‐Chotzen syndrome: Notable intrafamilial phenotypic variability in a large family with Q28X TWIST mutation

Saethre‐Chotzen syndrome is an autosomal dominant disease characterized by craniosynostosis, ptosis, and limb and external ear abnormalities. Variable expressivity is a well‐known phenomenon in this disorder. A large Indian family has been recently identified as carrying a nonsense TWIST mutation (Q28 X) in 17 members, of whom 16 were examined in detail. Only 4 (25%) of the patients showed patent craniostenosis, namely, oxycephaly. The penetrance of craniosynostosis in this family is lower than previously reported in the literature. Fifteen patients (93%) had moderate to severe ptosis. Minor limb and external ear abnormalities were present in most patients. Eyelid features were the hallmark of the disease for 12 members of the family, suggesting that mutations in TWIST may lead to a phenotype with mainly palpebral features and no craniostenosis. The clinical analysis of this large family clearly illustrates the significant variable expressivity, probably related to haploinsufficiency because of the TWIST mutation. This phenotypic variability remains unclear but could be the result of modifier genes and/or genetic background effect, as noticed previously in the transgenic twist‐null heterozygous mice. © 2002 Wiley‐Liss, Inc.     

Effects of task difficulty and invested mental effort on peripheral vasoconstriction

We ran two experiments to investigate whether peripheral arterial tone reflects changes in mental effort. Finger pulse wave amplitude, interpulse interval, and pulse variability in the mid- and high-frequency bands were recorded by means of a newly developed finger plethysmograph during both rest and cognitive performance. Using a modified version of the Sternberg memory task, we selectively manipulated either the difficulty of the task (Experiment 1) or the subjects' level of engagement in the task (Experiment 2). We found a significant difference in finger pulse wave amplitude between rest and task periods, suggesting that the measure reflects changes in sympathetic activity due to task engagement. In addition, our results suggest that reduced pulse wave amplitude, signaling vasoconstriction, occurs when subjects are investing effort.     

溶栓治疗后急性心肌梗死患者心率变异性的变化

目的观察急性心梗患者(AMI)溶栓后心率变异性(HRV)变化。方法41例患者被分为两组溶栓再通组21例;常规治疗组20例。观察两组患者病后心率变异性的改变。结果溶栓再通组病人在各时间点的HRV均高于常规治疗组(P<0.05);组内比较,3月、6月时的HRV均高于2周时(P<0.05)。2周时再通者室性心律失常低于常规治疗组(P<0.05)。结论溶栓后冠脉再通可改善心脏自主神经系统功能,减少室性心律失常。     

Atrial automaticity and atrioventricular conduction in athletes: contribution of autonomic regulation

Little is known about the sinoatrial automatism and atrioventricular conduction of trained individuals who present a normal resting electrocardiogram. We used transesophageal atrial stimulation, a minimally invasive technique, to evaluate aerobically trained athletes (n=10) and sedentary individuals (n=10) with normal resting electrocardiograms, to test the hypothesis that parasympathetic tone, as detected by heart rate variability, could be associated with changes in sinoatrial automatism and atrioventricular conduction. Corrected sinus node recovery time tended to be longer in athletes than in sedentary individuals, but this difference did not reach statistical significance. The Wenckebach point occurred at a lower rate in athletes than in the controls. Over a 24-h period of measurement, the mean RR interval was longer in the athletes than in the sedentary individuals. The mean square root of successive differences (rMSSD) tended to be higher in athletes than in controls, but this difference did not reach statistical significance. There was a moderate correlation (r=0.48, P < 0.05) between the index of atrioventricular conduction, the rate at the Wenckebach point, and the logarithmically transformed rMSSD. Thus, as a corollary to its effects on the sinus node, where increased parasympathetic tone, decreased sympathetic tone, and non-autonomic components may contribute to sinus bradycardia, it is possible that athletic training may also induce intrinsic adaptations in the conduction system, which could contribute to the higher prevalence of atrioventricular conduction abnormalities observed in athletes. Accepted: 2 January 2000     

Genetic variability of hepatitis C virus in chronically infected patients with viral breakthrough during interferon-ribavirin therapy

Little is known about hepatitis C virus (HCV) breakthrough during antiviral therapy, although it would help in understanding HCV resistance to current antiviral treatments. To analyse the implication of virological factors and the vigour of humoral immune responses in this phenomenon, we studied nine chronic hepatitis C patients with a viral breakthrough during IFN/ribavirin combination therapy, as well as five responders and five non-responders. The IRES and regions coding for the capsid protein, the PePHD domain of envelope glycoprotein E2 and the NS5A and 5B proteins were amplified by RT-PCR before treatment, before and during breakthrough, and after treatment. The major variant sequence was obtained by direct sequencing. The heterogeneity of quasispecies was studied by SSCP in all patients and sequencing after cloning in seven genotype 1b-infected patients. Humoral responses against HCV epitopes were also analysed. The major sequences of IRES, PePHD, and NS5B remained stable during treatment, regardless of the treatment response. However, the capsid protein and the regions flanking PePHD showed sequence variations in breakthrough patients, although no specific mutation was identified. The variable V3 region of NS5A, but not the PKR-binding domain and the ISDR, seemed to be associated with differences in response to treatment. The analysis of HCV quasispecies revealed no characteristic pattern during treatment in breakthrough patients, whose HCV genome profiles looked most similar to that of non-responders. The humoral response was similar between groups. In conclusion, viral breakthrough does not seem to be due to selection of resistant strains with signature mutations.     

Localization,structure and polymorphism of two paralogous <Emphasis Type="Italic">Xenopus laevis</Emphasis> mitochondrial malate dehydrogenase genes

Two paralogous mitochondrial malate dehydrogenase 2 (Mdh2) genes of Xenopus laevis have been cloned and sequenced, revealing 95% identity. Fluorescence in-situ hybridization (FISH) combined with tyramide amplification discriminates both genes; Mdh2a was localized into chromosome q3 and Mdh2b into chromosome q8. One kb cDNA probes detect both genes with 85% accuracy. The remaining signals were on the paralogous counterpart. Introns interrupt coding sequences at the same nucleotide as defined for mouse. Restriction polymorphism has been detected in the first intron of Mdh2a, while the individual variability in intron 6 of Mdh2b gene is represented by an insertion of incomplete retrotransposon L1Xl. Rates of nucleotide substitutions indicate that both genes are under similar evolutionary constraints. X. laevis Mdh2 genes can be used as markers for physical mapping and linkage analysis.     

Is There Association between Altered Adrenergic System Activity and Microvascular Endothelial Dysfunction Induced by a 7-Day High Salt Intake in Young Healthy Individuals

This study aimed to test the effect of a 7-day high-salt (HS) diet on autonomic nervous system (ANS) activity in young healthy individuals and modulation of ANS on microvascular endothelial function impairment. 47 young healthy individuals took 7-day low-salt (LS) diet (3.5 g salt/day) followed by 7-day high-salt (HS) diet (~14.7 g salt/day). ANS activity was assessed by 24-h urine catecholamine excretion and 5-min heart rate variability (HRV). Skin post-occlusive reactive hyperemia (PORH) and acetylcholine-induced dilation (AChID) were assessed by laser Doppler flowmetry (LDF). Separately, mental stress test (MST) at LS and HS condition was conducted, followed by immediate measurement of plasma metanephrines’ level, 5-min HRV and LDF microvascular reactivity. Noradrenaline, metanephrine and normetanephrine level, low-frequency (LF) HRV and PORH and AChID significantly decreased following HS compared to LS. MST at HS condition tended to increase HRV LF/HF ratio. Spectral analysis of PORH signal, and AChID measurement showed that MST did not significantly affect impaired endothelium-dependent vasodilation due to HS loading. In this case, 7-day HS diet suppressed sympathetic nervous system (SNS) activity, and attenuated microvascular reactivity in salt-resistant normotensive individuals. Suppression of SNS during HS loading represents a physiological response, rather than direct pathophysiological mechanism by which HS diet affects microvascular endothelial function in young healthy individuals.     

老年糖尿病患者运动状况及血糖控制情况研究

目的 研究老年糖尿病患者运动状况及血糖控制情况。方法 以2020年1月至2021年12月商丘市某医院诊治的老年糖尿病患者为研究对象,自制调查问卷获取患者的基本资料（包括性别、年龄、文化程度、居住地、病程、糖尿病并发症和其他基础疾病）,采用老年糖尿病患者运动锻炼评估量表评估运动状况,采用血生化指标检测评估血糖控制达标情况,分析老年糖尿病患者运动状况、血糖控制达标情况及其影响因素。结果 共纳入有效研究对象1 173例,其中男645例（54.99%）,年龄60~84岁,以60~69岁为主（45.69%）,文化程度以初中及以下为主（51.66%）,居住地以农村为主（56.61%）,病程以<5年为主（65.47%）,无糖尿病并发症者占90.88%,无其他基础疾病者占79.71%。血糖控制达标389例,达标率33.16%。运动状况总分（114.39±; 20.53）分,血糖未达标患者的运动状况总分及运动知识、运动行为、专业支持维度评分均显著低于血糖达标患者（均P<0.01）。多因素Logistic回归分析结果显示,病程（OR=0.689）、糖尿病并发症（OR=0.498）、其他基础疾病（OR=0.842）是老年糖尿病患者血糖达标的影响因素。结论 老年糖尿病患者运动状况有待改善,应针对不同情况的老年糖尿病患者进行个体干预,通过宣传教育提高运动知识认知及运动意愿,改善运动行为,增强运动锻炼的社会支持和专业支持,以促进血糖达标。     

美托洛尔对室性心律失常患者的心率变异性的影响

目的　研究美托洛尔对室性心律失常的疗效及其对心率变异性的影响。方法　对 36例Holter证实有频繁室性心律失常的患者 ,测定服药前后HRVI ,以统计学方法进行分析。结果　应用美托洛尔治疗后 ,室性心律失常明显减少 ,心率变异指数明显增加 ,较用药前有显著差异 (P <0 0 1)。结论　美托洛尔对室性心律失常疗效显著 ,并使心率变异性增加