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ABSTRACT: Examinations and quizzes should be used as learning as well as assessment tools. To achieve this goal, an assessment procedure was developed to enhance as well as assess student learning. Students were tested on four different topics of cardiovascular physiology. Each topic was tested by a different type of quiz (fill in the blanks, single best response multiple choice, short essay, or true/false). The students first completed a quiz individually. Once the quiz was completed individually, the students completed the same quiz in groups. Eighty percent of the score on the quiz was based on the individual results, and 20% of the score on the quiz was based on the group results. The performance on the quizzes was significantly higher (P < 0.001) when students completed the quizzes in groups than when they completed the quizzes individually. Results document that completing the quizzes in groups enhances the understanding of the material. In addition, students rated this format superior to the traditional method.
AJP Advances in Physiology Education 12/2002; 26(1-4):37-41. · 1.55 Impact Factor
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ABSTRACT: It is well known that nitric oxide (NO), within the paraventricular nucleus (PVN) of the hypothalamus, mediates sympatho-inhibition via an inhibitory GABA-ergic mechanism. Furthermore, the inhibitory GABA-ergic mechanism is impaired in the spontaneously hypertensive rat (SHR). These data suggest that the NO system, within the PVN, may also be impaired in the SHR. In addition, previous studies have documented that daily exercise attenuates the development of tachycardia, hypertension and blood pressure related cardiovascular disease risk factors in SHR. These data suggest that daily exercise enhances the inhibitory GABA-ergic and/or NO systems. Therefore, this study was designed to test the hypothesis that hypertension, in the SHR, is associated with a lower number of NADPH-diaphorase (a commonly used marker for neuronal NOS activity) positive neurons within the PVN and that daily exercise increases the number of NOS positive neurons. Using a standard histochemical protocol, NOS positive neurons were measured in the PVN, supraoptic nucleus, median preoptic area, lateral hypothalamus, nucleus of the tractus solitarius and rostral ventrolateral medulla. Results document that SHR have significantly fewer NOS-positive neurons in the PVN than their genetic control, the Wistar-Kyoto (WKY) rats (110+/-11 versus 139+/-17). Furthermore, daily exercise increased the number of NOS positive neurons in the SHR to levels seen in the WKY rats. These data demonstrate that hypertension, in the SHR, is associated with a lower number of NOS positive neurons within the PVN and that daily exercise increases the number of NOS positive neurons within the PVN.
Brain Research 12/2002; 955(1-2):153-60. · 2.73 Impact Factor
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ABSTRACT: Individuals with spinal cord injuries above thoracic level 6 experience episodic bouts of life-threatening hypertension as part of a condition termed autonomic dysreflexia (AD). The hypertension can be caused by stimulation of the skin, distension of the urinary bladder or colon, and/or muscle spasms. Transcutaneous electrical nerve stimulation (TENS) may reduce the severity of AD because TENS has been used to inhibit second-order neurons in the dorsal horn. Therefore, we tested the hypothesis that TENS attenuates the hemodynamic responses to colon distension. Eleven Wistar rats underwent spinal cord transection between thoracic vertebrae 4 and 5 (paraplegic, n = 6) or between cervical vertebra 7 and thoracic vertebra 1 (quadriplegic, n = 5). After recovery, all rats were instrumented with a radiotelemetry device for recording arterial pressure. Subsequently, the hemodynamic responses to graded colon distension were determined before and during TENS. During TENS the hemodynamic responses to colon distension were significantly attenuated. Thus TENS may be a preventive approach to reduce the severity of AD in paraplegic and quadriplegic individuals.
AJP Heart and Circulatory Physiology 11/2002; 283(4):H1734-9. · 3.71 Impact Factor
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ABSTRACT: Individuals with spinal cord injuries above thoracic level 6 (T(6)) experience life-threatening bouts of hypertension, termed autonomic dysreflexia (AD). AD is mediated by peripheral alpha-adrenergic receptor supersensitivity as well as a reorganization of spinal pathways controlling sympathetic preganglionic neurons. A single bout of dynamic exercise may be a safe therapeutic approach to reduce the severity of AD because mild-to-moderate dynamic exercise reduces postexercise alpha-adrenergic receptor responsiveness, lowers postexercise sympathetic nerve activity, and reduces the postexercise response to stress. Therefore, this study was designed to test the hypothesis that mild-to-moderate dynamic exercise attenuates the postexercise response to colon distension (mechanism to elicit AD). To test this hypothesis, six male Wistar rats (406 +/- 23 g), 5 wk post-T(5) spinal cord transection, were instrumented with an arterial catheter. After recovery, the response to graded colon distension (10, 30, 50, and 80 mmHg, in random order) was determined before and after a single bout of mild-to-moderate dynamic exercise (9-12 m/min, 0% grade for 40 min). After exercise, the pressor response to graded colon distension was significantly attenuated (preexercise change: 2 +/- 1, 9 +/- 1, 14 +/- 1, and 24 +/- 2 vs. postexercise change: 2 +/- 1, 2 +/- 1, 9 +/- 1, and 12 +/- 3 mmHg). Thus acute exercise is a safe, therapeutic approach to reduce the severity of AD in paraplegic subjects.
AJP Heart and Circulatory Physiology 05/2002; 282(4):H1566-70. · 3.71 Impact Factor
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ABSTRACT: We tested the hypothesis that a single bout of dynamic exercise produces a postexercise hypotension (PEH) and alpha(1)-adrenergic receptor hyporesponsiveness in spontaneously hypertensive rats (SHR). The postexercise alpha(1)-adrenergic receptor hyporesponsiveness is due to an enhanced buffering of vasoconstriction by nitric oxide. Male (n = 8) and female (n = 5) SHR were instrumented with a Doppler ultrasonic flow probe around the femoral artery. Distal to the flow probe, a microrenathane catheter was inserted into a branch of the femoral artery for the infusion of the alpha(1)-adrenergic receptor agonist phenylephrine (PE). A microrenathane catheter was inserted into the descending aorta via the left common carotid artery for measurements of arterial pressure (AP) and heart rate. Dose-response curves to PE (3.8 x 10(-3) - 1.98 x 10(-2)microg/kHz) were generated before and after a single bout of dynamic exercise. Postexercise AP was reduced in male (13 +/- 3 mmHg) and female SHR (18 +/- 7 mmHg). Postexercise vasoconstrictor responses to PE were reduced in males due to an enhanced influence of nitric oxide. However, in females, postexercise vasoconstrictor responses to PE were not altered. Results suggest that nitric oxide- mediated alpha(1)-adrenergic receptor hyporesponsiveness contributes to PEH in male but not female SHR.
AJP Regulatory Integrative and Comparative Physiology 05/2002; 282(4):R960-8. · 3.34 Impact Factor
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ABSTRACT: Cortright, R. N., M. P. Chandler, P. W. R. Lemon and S. E. Dicarlo. Daily exercise reduces fat, protein and body mass in male but not female rats. Physiol Behav 62(1): 105–111, 1997.—This study was designed to compare the estimated energy balance, linear growth (body and bone lengths) and body composition (all components including body mass, total body water, fat, protein and ash) response to daily spontaneous running (DSR) in young male and female rats. We tested the hypothesis that due to gender differences in energy efficiency, DSR would reduce linear growth and body composition more in male rats. Fourteen male and sixteen female weanling Sprague-Dawley rats were randomly assigned to either a sedentary (SED) control (male 7, female 8) or DSR (male 7, female 8) group. The DSR rats were allowed to run spontaneously in running wheels while SED rats remained in standard rat cages for 9 weeks. Body mass, running distance and food intake were measured over the nine week period. Subsequently, chemical analysis was performed to measure carcass content of water, protein, fat and ash. Linear growth was assessed by measures of body and bone lengths. The estimated energy balance of the DSR rats was computed and compared between genders. Estimated energy balance was significantly more negative in females than males due to significantly greater DSR distance. Body and bone lengths were similar among the SED and DSR female and SED and DSR male rats. However, whole body mass, fat mass and protein mass were significantly lower only in DSR males. These results demonstrate that DSR reduced body mass, body fat and protein mass in male rats but not in female rats despite a more negative estimated energy balance in female rats. These findings suggest that females are better protected from an energy deficit due to DSR. Possible mechanisms include gender-specific hormonal responses.
Physiology & Behavior 08/1997; · 2.87 Impact Factor
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ABSTRACT: 1. Background: The post-exercise period is associated with a profound decrease in sympathetic activity and arterial pressure. We have recently shown that endurance exercise training in rats is associated with highly significant decreases of low frequency (LF: 0.19–) power of blood pressure (BP). In this study, we measured cardiac output (CO) and systolic blood pressure (SBP) continuously for at least in rats before (n=5) and after (n=4) exercise. The purpose of this study was to determine if acute exercise produces post-exercise changes in the low frequency power (LF: 0.19–) of CO as the decrease in this band of BP appears to be mediated by the sympathetic nervous system.2. Methods: The data were sampled at and the HR time series were derived from the SBP signal. The signals were sampled at and the spectral powers were obtained in the following bands; total power (TP: 0–), very low frequency power (VLF: 0–), low frequency power (LF: 0.19–) and high frequency power (HF: 1.2–). We also obtained the transfer magnitude and coherence between HR and CO. Finally, largest Lyapunov exponent (LLE) was obtained as a measure of chaos for HR and CO before and after exercise.3. Results: There was a significant decrease in LLE of CO (p<0.05) after exercise.4. Conclusions: These results suggest that the CO time series appear to be chaotic in nature and the decrease in LLE after exercise, especially in relation to HR appears to be due to a decrease in sympathetic activity. These new nonlinear techniques may prove to be of additional value to the linear measures such as spectral analysis.
Nonlinear Analysis: Real World Applications.
