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81.
The respiratory-dependent pacemaker (RDP3 or MB-1, Biorate, Biotec International, S.p.A., Bologna, Italy) detects the respiratory rate by measuring thoracic impedance using a subcutaneous auxiliary lead. The sensed respiratory rate is used to determine the pacing rate response. This pacemaker had been implanted in 9 patients with a mean age of 58 (range 42-69) years. During symptom-limited treadmill exercise, rate-modulated pacing resulted in a significant increase in pacing rate (mean +/- SD, 124 +/- 10 vs. 71 +/- 3 beats/min p less than 0.001) and exercise capacity (343 +/- 147 vs. 463 +/- 120 s, p less than 0.05) compared to those achieved with constant rate ventricular pacing. Brief treadmill exercise tests showed appropriate rate response to increased walking speed and gradient. However, rate response was modified by arm swinging-induced motion artefact which affected the measured "impedance." Complications observed on follow-up included perforation of the auxiliary lead in 2 patients and symptomatic myopotential interference in 3 patients with the RDP3 pacemaker, all of whom required unit replacement. It is concluded that although the respiratory-dependent pacemaker can confer physiological benefit in patients with bradycardia, myopotential interference (largely overcome by the new version MB-1 with programmable sensitivity) and the auxiliary lead can be problematic in some patients. 相似文献
82.
GROB D.; HESS O. M.; MONRAD E.; BIRCHLER B.; GRIMM J.; KRAYENBUEHL H. P. 《European heart journal》1988,9(1):73-86
Left ventricular (LV) wall thickness and muscle mass are importantmeasures of LV hypertrophy. In 24 patients LV end-diastolicwall thickness and muscle mass were determined (two observers)by digital subtraction angiocardiography (DSA) and conventionalLV angiocardiography (LVA). Wall thickness was determined overthe anterolateral wall of the left ventricle according to thetechnique of Rackley (method 1) or by planimetry (method 2).Seventeen patients were studied at rest and seven during dynamicexercise. Wall thickness correlated well between LVA and DSA;the best correlations were obtained by a combined subtractionmode using either method 1 or 2 (method 1, r080; method2,r0. 75). The standard error of estimate of the mean (SEE) wasslightly lower for method 2 ( 10%) than for method 1 ( 13%).DSA significantly overestimated wall thickness by 57%with method 1 and underestimated by 1214% with method2. Muscle mass correlated well between LVA and DSA; the SEEwas 15% for method 1 and 12% for method 2. Overestimation ofmuscle mass by DSA was 711% with method 1 and underestimationwas 1315% with method 2.It is concluded that LV wallthickness can be determined accurately by DSA with an SEE rangingbetween 10 and 13%. Determination of LV muscle mass is slightlyless accurate and the SEE is slightly larger ranging between13 to 17%. With method 1, wall thickness and muscle mass wereover estimated and with method 2 underestimated. 相似文献
83.
<正>上交叉综合征(upper crossed syndrome,UCS)是指因上半身长期处于不良姿势,造成相关肌群功能失衡,进而引起颈肩背部疼痛不适、胸闷、睡眠障碍等一系列不良症状的一种亚健康状态[1]。UCS常见的体态是圆肩、驼背、头前倾[2]。目前临床上主要通过纠正局部的肌肉失衡来治疗UCS,常用的方法有运动疗法、肌肉能量技术、针灸和推拿等[3]。 相似文献
84.
Rob A. Binkhorst Berend Oeseburg Maria T. E. Hopman 《European journal of applied physiology》1992,65(1):73-78
Summary The purpose of this study was to examine cardiovascular responses during arm exercise in paraplegics compared to a well-matched control group. A group of 11 male paraplegics (P) with complete spinal cord-lesions between T6 and T12 and 11 male control subjects (C), matched for physical activity, sport participation and age performed maximal arm-cranking exercise and submaximal exercise at 20%, 40% and 6070 of the maximal load for each individual. Cardiac output (Q
c) was determined by the CO2 rebreathing method. Maximal oxygen uptake was significantly lower and maximal heart rate (f
c) was sigificantly higher in P compared to C. At the same oxygen uptakes no significant differences were observed inQ
c between P and C; however, stroke volume (SV) was significantly lower andf
c significantly higher in P than in C. The lower SV in P could be explained by an impaired redistribution of blood and, therefore, a reduced ventricular filling pressure, due to pooling of venous blood caused by inactivity of the skeletal muscle pump in the legs and lack of sympathetic vasoconstriction below the lesion. In conclusion, in P maximal performance appears to have been limited by a smaller active muscle mass and a lower SV despite the higher c,max. During submaximal exercise, however, this lower SV was compensated for by a higherf
c and, thus at the same submaximal oxygen uptake,Q
c was similar to that in the control group. 相似文献
85.
Turnip crinkle virus coat protein mediates suppression of RNA silencing in Nicotiana benthamiana 总被引:11,自引:0,他引:11
All of the protein products of Turnip crinkle virus (TCV; Tombusviridae, Carmovirus) were tested for their ability to suppress RNA silencing of a reporter gene after transient expression in Agrobacterium-infiltrated Nicotiana benthamiana leaves. Only the capsid protein, P38, showed suppression activity, although this was not obvious when P38 was expressed as part of a TCV infection of the same tissues. When P38 was expressed from a PVX vector, symptoms with enhanced severity that correlated with increased PVX RNA accumulation were observed. This contradiction between ectopic expression of P38 and TCV infection could be accounted for if the active determinant of suppressor activity within P38 was sequestered within the capsid protein structure. The N-terminal 25 amino acids were shown to be important for this activity. This region forms part of the unexposed R-domain that interacts with the RNA within the virus particle. This observation throws light on some of the complex biology exhibited by TCV. 相似文献
86.
M. B. REID 《Acta physiologica (Oxford, England)》1998,162(3):401-409
Over the last two decades, nitric oxide (NO) has been established as a novel mediator of biological processes, ranging from vascular control to long-term memory, from tissue inflammation to penile erection. This paper reviews recent research which shows that NO and its derivatives also are synthesized within skeletal muscle and that NO derivatives influence various aspects of muscle function. Individual muscle fibres express one or both of the constitutive NO synthase (NOS) isoforms. Type I (neuronal) NOS is localized to the sarcolemma of fast fibres; type III (endothelial) NOS is associated with mitochondria. Isolated skeletal muscle produces NO at low rates under resting conditions and at higher rates during repetitive contraction. NO appears to mediate cell–cell interactions in muscle, including vasodilation and inhibition of leucocyte adhesion. NO also acts directly on muscle fibres to alter cell function. Muscle metabolism appears to be NO-sensitive at several sites, including glucose uptake, glycolysis, mitochondrial oxygen consumption and creatine kinase activity. NO also modulates muscle contraction, inhibiting force output by altering excitation–contraction coupling. The mechanisms of NO action are likely to include direct effects on redox-sensitive regulatory proteins, interaction with endogenous reactive oxygen species, and activation of second messengers such as cyclic guanosine monophosphate (cGMP). In conclusion, research published over the past few years makes it clear that skeletal muscle produces NO and that endogenous NO modulates muscle function. Much remains to be learned, however, about the physiological importance of NO actions and about their underlying mechanisms. 相似文献
87.
M. Parczewski J. Kordek E. Janczewska A. Pisula W. Łojewski Ł. Socha M. Wawrzynowicz-Syczewska M. Bociąga-Jasik A. Szymczak I. Cielniak E. Siwak E. Mularska B. Aksak-Wąs A. Urbańska N. Lübke 《Clinical microbiology and infection》2019,21(4):513.e1-513.e6
Objectives
The aim of the study was to characterize the differences in the frequencies of NS3 and NS5A resistance-associated variants (RAVs) among Polish therapy-naive genotype 1 (G1) hepatitis C virus (HCV)-monoinfected and human immunodeficiency virus (HIV)/HCV-coinfected patients including clustering patterns and association of RAV frequency with liver fibrosis.Methods
NS3/NS5A RAVs were identified by population sequencing in 387 directly acting antiviral treatment-naive G1-infected individuals (54 with genotype 1a (G1a) and 333 with genotype 1b (G1b)). Liver fibrosis was assessed based on histopathology or ultrasound elastography. Phylogenetic clusters were identified using maximum likelihood models. For statistics, chi-squared or two-sided Fisher's exact tests and multivariate logistic regression models were used, as appropriate.Results
NS3 RAVs were found in 33.33% (18/54) for G1a and 2.62% (8/297) for G1b whereas NS5A variants were present in 5.55% (3/54) G1a and 9.31% (31/333) G1b sequences. Variations in NS5A 31 and 93 codon positions were found only in G1b (4.2% (14/333) for L31I/F/M and 5.39% (17/333) for Y93H). NS5A RAVs were more frequent among patients with advanced liver fibrosis (17.17% (17/99) for F3–F4 versus 6.94% (17/245) for F0–F2; p 0.004) or liver cirrhosis (20.34% (12/59) for F4 versus 7.72% (22/285) for F0–F3; p 0.003). Liver cirrhosis (F4) was associated with higher odds ratio of the NS5A RAVs among HCV-infected patients (odds ratio 2.34, 95% CI 1.004–5.291; p 0.049). NS5A RAVs were less frequent among sequences forming clusters and pairs (5.16% (8/155) versus 11.21% (26/232); p 0.039).Conclusions
Presence of NS5A RAVs correlated with progression of liver fibrosis and represents de novo selection of variants rather than transmission of drug resistance. Hence, the presence of NS5A RAVs may be a predictor for a long-lasting HCV infection. 相似文献88.
中国东北地区未经抗病毒治疗的HIV/AIDS患者HIV毒株的耐药基因变异研究 总被引:10,自引:0,他引:10
目的 研究我国东北地区未接受抗逆转录病毒治疗的HIV AIDS患者HIV毒株的逆转录酶和蛋白酶耐药变异情况 ,为开展大规模临床抗病毒药物治疗提供本底数据。方法 RT PCR和套式PCR扩增HIVpol区基因 ,双脱氧法测定逆转录酶和蛋白酶基因序列 ,与国际耐药数据库比对辨别耐药变异。结果 (1) 5 3例患者毒株亚型分析结果 :B′亚型 4 7例 ,B′ C亚型 4例 ,A、B亚型各 1例 ;(2 )未发现逆转录酶和蛋白酶原发耐药变异存在 ,但发现存在逆转录酶抑制剂继发变异 :M4 1L(1.9% )、I6 3M (1.9% )、L74I (1.9% )、S6 8G (1.9% )、V75L (3.8% )、V10 6I (1.9% )、I135L T (5 .7% )、V179D (7.5 % )和V189I (1.9% ) ,无症状感染者RT继发耐药变异出现率为 11.8% ,而艾滋病患者为5 2 .6 % (P <0 .0 1)。存在大量蛋白酶耐药继发变异V77I (88.7% )、L6 3P (86 .8% )、E35D (81% )、A71V(2 4 .5 % )、R4 1K (15 .1% )、L10I (9.4 % )、R5 7K (9.4 % )、D6 0E (9.4 % )、N37D (5 .7% )、G16E (3.8% )、I15V (1.9% )、M36I (1.9% )、K5 5R (1.9% )和L89M (1.9% )。未发现明显的亚型特异性耐药变异。结论 在中国东北地区未接受抗逆转录病毒治疗的HIV AIDS患者中未发现毒株逆转录酶和蛋白酶耐药原发变异 ,但大量继发耐药变异的存在提 相似文献
89.
R. Kinscherf V. Hack T. Fischbach B. Friedmann C. Weiss L. Edler P. Bärtsch W. Dröge 《Journal of molecular medicine (Berlin, Germany)》1996,74(7):393-400
Skeletal muscle catabolism, low plasma glutamine, and high venous glutamate levels are common among patients with cancer or human immunodeficiency virus infection. In addition, a high glycolytic activity is commonly found in muscle tissue of cachectic cancer patients, suggesting insufficient mitochondrial energy metabolism. We therefore investigated (a) whether an anaerobic physical exercise program causes similar changes in plasma amino acid levels, and (b) whether low plasma glutamine or high glutamate levels are risk factors for loss of body cell mass (BCM) in healthy human subjects, i.e., in the absence of a tumor or virus infection. Longitudinal measurements from healthy subjects over longer periods suggest that the age-related loss of BCM occur mainly during episodes with high venous glutamate levels, indicative of decreased muscular transport activity for glutamate. A significant increase in venous glutamate levels from 25 to about 40 M was seen after a program of anaerobic physical exercise. This was associated with changes in T lymphocyte numbers. Under these conditions persons with low baseline levels of plasma glutamine, arginine, and cystine levels also showed a loss of BCM. This loss of BCM was correlated not only with the amino acid levels at baseline examination, but also with an increase in plasma glutamine, arginine, and cystine levels during the observation period, suggesting that a loss of BCM in healthy individuals terminates itself by adjusting these amino acids to higher levels that stabilize BCM. To test a possible regulatory role of cysteine in this context we determined the effect of N-acetyl-cysteine on BCM in a group of subjects with relatively low glutamine levels. The placebo group of this study showed a loss of BCM and an increase in body fat, suggesting that body protein had been converted into other forms of chemical energy. The decrease in mean BCM/body fat ratios was prevented by N-acetyl-cysteine, indicating that cysteine indeed plays a regulatory role in the physiological control of BCM.Abbreviations
BCM
Body cell mass
-
HIV
Human immunodeficiency virus type 1
-
NAC
N-Acetyl-cysteine 相似文献
90.
S. Haruyama H. Mori L. M. Wan Y. Shinozaki H. Sakamoto H. Okino 《Medical & biological engineering & computing》1994,32(Z1):S91-S98
We proposed a mathematical model to describe the early filling process of the left ventricle and applied the model toin vivo experiments. The solution of a second-order differential equation indicated that the pressure difference between the left
atrium and ventricle during ventricular filling (PD) could be explained by a transient response, i.e. decremental oscillation,
in an LCR circuit. Thereafter, we analysed the sequence of PD during vagal stimulation with two catheter-tip manometers in
12 anaesthetised dogs and evaluated changes in the parameters of the system under various haemodynamic conditions. The values
of ωn and ξ were quite stable among beats within an episode of vagal stimulation, between episodes and even among dogs, despite
the changes in haemodynamic variables. Pericardiotomy and partial discommunication of the mitral valve with the left ventricular
free wall by cutting the mitral chordal tendons decreased ωn and increased ζ, mainly because of the increase in CLV. Occlusion of the coronary vascular beds with large numbers of microspheres increased ωn and decreased ζ, mainly because of the decrease in CLV. Mitral obstruction with an inflated balloon (increase in R) abolished the oscillatory changes and produced and exponential
decay sequence of PD. In conclusion, both the logical and experimental approaches indicated that the sequence of PD could
be considered as decremental oscillation in the LCR circuit and the parameters ωn and ξ could be good indices of the diastolic property of the left ventricle 相似文献