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101.
102.
103.
The time of appearance of the truncus arteriosus was studied in the chick embryo using an in ovo labeling technique. Three hundred embryos at stages 13–18 of Hamburger and Hamilton were selectively labeled at the distal end of the heart tube, using gelatine-india ink label; 122 of these embryos were reincubated and 111 of them reached stages 25–28. In these stages the final location of the label was determined. Only 95 of these embryos showed both a normal heart and a label located in it. The remaining embryos were discarded due to abnormal cardiac morphology or because the label was not found. Embryos labeled at stages 13–14 had label in the conus in 42.8% of the cases and in the boundary between the conus and the truncus arteriosus in 57.1% of the cases. Label placed at stages 15–16 was located in the conus in 6.1% of the cases, in the boundary between the conus and the truncus arteriosus in 44.8% of the cases, and in the truncus arteriosus in 48.9% of the cases. Finally, label placed at stages 17–18 was located in the boundary between the conus and the truncus arteriosus in 18.7% of the cases and in the truncus arteriosus in 81.2% of the cases. Our results permit us to conclude that the truncus arteriosus appears in the chick embryo as early as stages 15–16 of Hamburger and Hamilton (50–56 hours of incubation). © 1993 Wiley-Liss, Inc. 相似文献
104.
Alcohol and the Psychophysiological Detection of Deception 总被引:1,自引:0,他引:1
Psychophysiological detection of deception examinations were conducted on 40 subjects. Of these, 32 were “guilty” of a mock crime and 8 were innocent. Sixteen guilty subjects committed the crime while intoxicated and the remaining 16 committed the crime sober. These two groups of guilty subjects were subdivided such that half of each group was examined with the polygraph while intoxicated and the other half was examined while sober. Two questioning techniques were used in the examination, a Control Question Test and the Guilty Knowledge Test. Measures of skin resistance, heart rate and respiration were recorded. The principal findings were that alcohol intoxication during the crime reduced detectability with detection scores derived from the measurement of skin resistance responses on the Control Question Test and on the Guilty Knowledge Test. The analyses of guilt/innocent classifications, based on the detection scores, showed these classifications to be affected by alcohol intoxication. 相似文献
105.
Shigemitsu Iwai MD Kei Torikai MD Chris M. Coppin MD Yoshiki Sawa MD 《Journal of artificial organs》2007,10(1):29-35
Currently used bioprosthetic valves have several limitations such as calcification and functional deterioration, and revitalization
through cellular ingrowth is impossible. To overcome these obstacles, we have developed a minimally immunogenic tissue-engineered
valve that consists of an unfixed, decellularized porcine valve scaffold capable of being spontaneously revitalized in vivo
after implantation. Porcine aortic root tissue was decellularized using detergents such as sodium lauryl sulfate and Triton
X-100. The porcine valve was treated very gently and plenty of time was allowed for constituents to diffuse in and out of
the matrix. In a preliminary study, a piece of decellularized porcine valve tissue was implanted into the rat subdermal space
for 14 and 60 days and the structural integrity and calcification were evaluated. As an in vivo valve replacement model, the
decellularized porcine valve was implanted in the pulmonary valve position in dogs and functional and histological evaluation
was performed after 1, 2, and 6 months. Histological examination showed that the newly developed detergent treatment effectively
removed cellular debris from the porcine aortic tissue. Decellularized porcine valve tissue implanted subdermally in rats
showed minimal inflammatory cell infiltration and calcification. In the valve replacement model, spontaneous reendothelialization
and repopulation of the medial cells were observed within 2 months, and good valve function without regurgitation was observed
by echocardiography up to 6 months. The minimally immunogenic decellularized porcine valve proved effective in mitigating
postimplant calcification and provided a suitable matrix for revitalizing prostheses through in situ recellularization, cellular
ingrowth, and tissue remodeling. 相似文献
106.
Effect of relaxation training on cardiac parasympathetic tone 总被引:8,自引:0,他引:8
To examine the hypothesis that the relaxation response is associated with an increase in cardiac parasympathetic tone, the frequency components of heart rate variability during relaxation training were investigated in 16 college students. Electrocardiograms and pneumograms were recorded during a 5-min baseline period followed by three successive 5-min sessions of the autogenic training (relaxation) or by the same periods of quiet rest (control), while subjects breathed synchronously with a visual pacemaker (0.25 Hz). Although neither the magnitude nor the frequeney of respiration showed a significant difference between relaxation and control, the amplitude of the high-frequency component of heart rate variability increased only during relaxation (p= .008). There was no significant difference in the ratio of the low-frequency (0.04–0.15 Hz) to the high-frequency amplitudes. The increased high-frequency amplitude without changes in the respiratory parameters indicates enhanced cardiac parasympathetic tone. Thus, our results support the initial hypothesis of this study. Enhanced cardiac parasympathetic tone may explain an important mechanism underlying the beneficial effect of the relaxation response. 相似文献
107.
Paul A. Obrist Richard A. Galosy James E. Lawler Claude J. Gaebelein James L. Howard Emily M. Shanks 《Psychophysiology》1975,12(4):445-455
The relationships between heart rate (HR) and several parameters of somatic activity were evaluated in human subjects when shuck avoidance was made contingent on either increases or decreases in HR. In order to depict any influence of the contingency specific 10 HR, somatic activity was controlled to varying degrees by instructions and the use of non-contingent control groups. When increases in HR were reinforced, the contingency we found to influence somatic activity but an effect specific to HR was also observed. When decreases in HR were reinforced, there was no evidence that HR were influenced independently of somatic activity. The result are discussed with respect to several current issues. 相似文献
108.
Edward Carmeliet Johan Vereecke 《Pflügers Archiv : European journal of physiology》1969,313(4):300-315
Summary Conduction block in heart cells by K+ rich, or Na+ depleted solutions can be overcome by adrenaline. In order to explain this phenomenon, the effect of adrenaline on the membrane resting and action potentials of cow Purkinje fibers was measured at various extracellular concentrations of Na+, K+ and Ca++, in the presence of tetrodotoxin, Mn++ and beta-receptor antagonists.It was found that adrenaline specifically increases the amplitude and duration of the plateau phase of the cardiac action potential. Plateu-like action potentials, without preceding Na+-spike, can be generated and conducted in an all-or-nothing way. In K+ rich solutions and under the influence of adrenaline, the depolarization proceeds in two steps. The first step corresponds to the Na+-spike. The second step or secondary depolarization corresponds to the plateau; it was not modified by changes of the membrane potential between –85 and –55 mV, or by reduction of extracellular Na+ ions, but was specifically blocked by Mn++ ions and beta-receptor antagonists. Its amplitude increased by 17 mV for a tenfold change in extracellular Ca++. Tetrodotoxin preferentially blocked the Na+-spike, but also slowed the rate of potential change during the secondary depolarization.The simplest explanation for the observed phenomena can be found in an increase of Ca++ inward current under the influence of adrenaline. The existence of an inward Na++ current, different in characteristics from the Na+ conductance during the fast upstroke, cannot be ruled out. Some data are in accord with a decrease in K+ conductance. 相似文献
109.
Jagdish Butany Manmeet S. Ahluwalia Craig Munroe Cristina Fayet Christina Ahn Patrick Blit Charis Kepron Roberto J. Cusimano Richard L. Leask 《Cardiovascular pathology》2003,12(6):322-344
Mechanical heart value prostheses have been in use since the 1950s. Many prostheses have been used for a while and then discontinued. Today, there are a large number and variety of prostheses in use and an even larger variety that are in place in patients. These may be explanted at any time for a number of reasons. It is essential for the practicing pathologist to be able to identify the prosthesis and be aware of some of its reported complications and modes of failure. This article, and a second one on bioprosthetic heart valves, is designed as a ready reference guide to heart valve prostheses, their important identifying features, their common complications, and modes of failure. It should help in the accurate identification of explanted prosthetic valves and more definitive reports. This accuracy of identification as well as tracking of abnormalities noted will, we hope, permit the identification of new failure modes and the recording of causes of failure of new (or even modified) prosthetic heart valves. 相似文献
110.
Analysis of heart rate variability (HRV) is a valuable, non-invasive method for quantifying autonomic cardiac control in humans.
Frequency-domain analysis of HRV involving myocardial ischaemic episodes should take into account its non-stationary behaviour.
The wavelet transform is an alternative tool for the analysis of non-stationary signals. Fourteen patients have been analysed,
ranging from 40 to 64 years old and selected from the European Electrocardiographic ST-T Database (ESDB). These records contain
33 ST episodes, according to the notation of the ESDB, with durations of between 40s and 12min. A method for analysing HRV
signals using the wavelet transform was applied to obtain a time-scale representation for very low-frequency (VLF), low-frequency
(LF) and high-frequency (HF) bands using the orthogonal multiresolution pyramidal algorithm. The design and implementation
using fast algorithms included a specially adapted decomposition quadrature mirror filter bank for the frequency bands of
interest. Comparing a normality zone against the ischaemic episode in the same record, increases in LF (0.0112±0.0101 against
0.0175±0.0208s2Hz−1; p<0.1) and HF (0.0011±0.0008 against 0.0017±0.0020s2Hz−1; p<0.05) were obtained. The possibility of using these indexes to develop an ischaemic-episode classifier was also tested.
Results suggest that wavelet analysis provides useful information for the assessment of dynamic changes and patterns of HRV
during myocardial ischaemia. 相似文献