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Biomedical subjects

G Kline

Publications and source records attributed to G Kline.

17 recordsLinked to original sources
PubMed2003

Contraction-sensitive skeletal muscle afferents inhibit arterial baroreceptor signalling in the nucleus of the solitary tract: role of intrinsic GABA interneurons.

Arterial baroreceptor and skeletal muscle receptor afferents relay sensory information to the nucleus of the solitary tract (NTS) during exercise. Previous studies have suggested that skeletal muscle afferent input inhibits baroreflex function; however, detailed information on the role of muscle afferents and GABAergic mechanisms in the NTS is limited. Furthermore, identification of specific afferent modalities that activate GABAergic neurons in the NTS remains unknown. In the present study, we examined the neuroanatomical and physiological interactions between spinal dorsal horn cells that transmit contraction-sensitive input from skeletal muscle and GABAergic interneurons in the NTS. Biotinylated dextran amine (BDA, 10%, 25-100 nL) microinjection into dorsal horn of the cervical spinal cord was combined with glutamate decarboxylase (GAD) immunohistochemistry to visualize the nature of the relationship of BDA-labeled fibers in the NTS with GAD immunoreactivity (GAD-ir). BDA-labeled axons and terminal processes were localized in the medial, commissural, dorsomedial and dorsolateral subdivisions of the caudal NTS. Moreover, BDA-labeled fibers were observed in close proximity to GAD-ir structures throughout these regions of the NTS. The physiological interaction between skeletal muscle receptor and arterial baroreceptor afferents was investigated using an arterially perfused, decerebrate rat preparation. Activation of skeletal muscle afferents by electrically evoked twitch contraction of the forelimb attenuated baroreflex responsiveness (BR, calculated as the ratio of changes in heart rate to systemic pressure) from -1.5+/-0.3 bpm.mm Hg(-1) to -0.1+/-0.1 bpm.mm Hg(-1) (control versus contraction, P<0.05, n=15). However, forelimb contraction failed to inhibit the reflex bradycardia evoked by activation of peripheral chemoreceptor afferents, indicating a reflex-specific action. Bilateral microinjection of bicuculline methiodide (BIC, 10 microM, 40-60 nL) into the caudal NTS restored baroreflex responsiveness during contraction (-1.6+/-0.2 versus -0.1+/-0.1 versus -1.5+/-0.2 bpm.mmHg(-1), control versus contraction versus contraction+BIC P<0.05, n=8). We conclude that activation of ascending spinal neurons from the cervical dorsal horn by contraction-sensitive skeletal muscle afferents selectively inhibits arterial baroreceptor signaling in the NTS via activation of a GABAergic mechanism.

Afferent Pathways↗
PubMed1999

One-mile run performance and cardiovascular fitness in children.

BACKGROUND: Endurance run tests are administered in schools to assess cardiovascular fitness, defined in the laboratory as maximum oxygen consumption. OBJECTIVE: To examine the validity of this concept, assessing the influences of body fat and maximum values of oxygen consumption per unit time, stroke volume, heart rate, and arteriovenous oxygen difference on 1-mile (1.6-km) run time in healthy sixth-grade boys. STUDY DESIGN: Subjects were 36 boys with a mean (SD) age of 12.2 (0.5) years. The relationship was examined between body fat content (estimated by skinfold measurements) and maximum oxygen consumption per kilogram and cardiac variables (during maximum cycle testing) with 1-mile run velocity. RESULTS: Body fat content and maximum oxygen consumption per kilogram (independent of body fat) accounted for 31% and 28% of the variance in run velocity, respectively. Stroke volume was the only component of maximum oxygen consumption that related to run performance. CONCLUSIONS: These findings suggest that cardiovascular fitness and body fat content contribute equally to 1-mile run time in healthy boys and together account for only 60% of the variance in performance on this endurance fitness test. Consequently, 1-mile run performance in children may not serve as a strong indicator of cardiovascular fitness.

Adipose Tissue↗
PubMed1998

Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program.

OBJECTIVE: To study the effects of a 12-week weight loss strategy involving increased physical activity, self-selected hypocaloric diet, and group support on psychological well-being, quality of life, and health practices in moderately obese women. METHODS: Eighty women aged 20-49 years weighing between 20-50% above 1983 Metropolitan Life Insurance Tables were randomly assigned to a weight loss intervention (6279 kJ/week of physical activity, 33,258-41,462 kJ/week diet and weekly meetings) or served as controls. Subjects were tested pre and post 12-weeks. RESULTS: The intervention group lost significant (p<0.001) body weight (kg) and body fat (%) compared to controls (-6.07+/-4.01 kg vs. 1.31+/-1.28 kg; 36.8%-32.5% vs. 36.2%-36.0%). Intervention subjects vs. controls achieved significant improvements (p<0.001) in body cathexis (X Change 18.6+/-16.7 vs. 0.7+/-8.6) and estimation of ability to achieve physical fitness (X Change 8.1+/-7.1 vs. 0.9+/-5.9). Various quality of life indices also improved (p<0.01) in the intervention group compared to controls (physical function: X Change 13.5.2+/-16.7 vs. 1.4+/-9.5; vitality: X change 21.7+/-17.9 vs. 2.9+/-20.8; mental health: X change 10.4+/-16.0 vs. 2.3+/-10.1). Similarly, physical activity levels also improved significantly (p<0.0001) in the intervention group (4.4+/-2.3 vs. 0.6+/-1.3; on NASA 0-7 scale). CONCLUSIONS: Practical weight loss practices such as increased activity, self-selected hypocaloric diet, and group support are effective for weight loss and yield significant health and psychological benefits in moderately obese females.

Adult↗
PubMed1996

Limitation of cardiac output by a coronary alpha 1-constrictor tone during exercise in dogs.

This study was performed to examine whether an alpha 1-constrictor tone, which limits coronary functional hyperemia during exercise, imposes a significant limitation on global cardiac performance as determined by cardiac output (CO). Seven dogs were chronically instrumented to measure left ventricular pressure (LVP), maximum rate of rise of LVP (dP/dtmax), heart rate (HR), mean aortic pressure (AoP), circumflex blood flow velocity (CFV), and CO at rest and during submaximal exercise. Either the selective alpha 1-adrenergic antagonist prazo (0.5 mg) or the vasodilator adenosine was administered into the circumflex artery during exercise at 6.4 kilometers per hour (kph)/16% treadmill incline. Exercise caused significant increase in mean AoP, HR, LVP, dP/dtmax, CFV, stroke volume (SV), and CO, whereas systemic vascular resistance (SVR) was significantly reduced. After intracoronary alpha 1-blockade with prazosin, CFV, dP/dtmax, SV, and CO increased further (17 +/- 2, 19 +/- 3, 16 +/- 2, and 17 +/- 2%, respectively) without changing mean AoP, HR, or SVR. Comparable increases were observed when CFV was increased by a similar degree using the direct vasodilator adenosine. These results indicate that increasing coronary flow by removing a coronary alpha 1-constrictor tone with prazosin or by direct vasodilation with adenosine during submaximal exercise leads to an increase in myocardial oxygen supply and, as a result, cardiac pump performance (SV and CO).

Adenosine↗
PubMed1994

Duodenal organ injury severity (OIS) and outcome.

The effect of organ injury severity on outcome was assessed in 101 patients treated for duodenal trauma. Most patients were men (89%) and victims of penetrating wounds (93%). Grade I is minor hematoma or incomplete perforation; Grade II is major hematoma or small complete perforation; Grade III is large perforation excluding ampulla; Grade IV is large perforation at ampulla; Grade V is duodenopancreatic crunch. The injuries were as follows: Grade I (5 patients), Grade II (31), Grade III (40), Grade IV (12), and Grade V (13). Fourteen patients exsanguinated from associated vessel injury; each had Grade IV or Grade V injury. All 36 patients with Grade I and Grade II injury had primary repair; the single death was due to liver necrosis. Most (31 patients) Grade III injuries and three Grade IV injuries were treated by primary repair alone; the three deaths were unrelated to the duodenal injury. Other major injuries were treated by duodenal exclusion (4 patients), duodenal diverticulization (6), or resection (4); the single death was unrelated to the duodenum. Primary closure is favored for minor injuries and most Grade III injuries. Severe injuries may require exclusion, diverticulization, or resection.

Adolescent↗
PubMed1994

Histocompatibility differences and cardiac transplant tolerance produced by intrathymic pretreatment.

Control of cardiac transplant rejection without toxic immunosuppressive drugs remains an unreached goal. Our laboratory and others have shown that intrathymic inoculation of donor-specific allogeneic spleen cells can produce tolerance to a subsequent cardiac allograft. The present experiments were designed to investigate whether the degree of donor-recipient histoincompatibility influenced the efficacy of this technique. Four congeneic strains of rats with different degrees of histoincompatibility were studied. Heterotopic cardiac transplantation was done with the following congeneic strain combinations: DA donor into PVG recipient (full major histocompatibility complex and nonmajor histocompatibility complex incompatibility); PVG.RT1a donor into PVG recipient (full major histocompatibility complex incompatibility); PVG.RT1a donor into PVG.R1 recipient (partial major histocompatibility complex incompatibility). Prospective graft recipients underwent intraperitoneal injection of 1 ml antilymphocyte serum and intrathymic injection of 5 x 10(7) prospective donor spleen cells. Three weeks later, heterotopic cardiac transplantation was done with a heart from a donor of the same strain as that used to obtain splenocytes for intrathymic injection. Prolongation of graft survival was observed in pretreated recipients in all strain combinations but was greatest in recipients that differed from donors at fewer histocompatibility loci. Complete graft tolerance was not seen in strain combinations that included nonmajor histocompatibility complex incompatibilities. DA heart survival in PVG recipients was 50.6 days (p < 0.04 versus controls); PVG.RT1a graft survival in PVG hosts was 165.8 days (p < 0.02 versus control) and in PVG.R1 recipients 163.8 days (p < 0.02 versus controls) with four of five grafts in each group surviving indefinitely (more than 200 days).

Animals↗
PubMed1993

Experiments in cardiac xenotransplantation. Response to intrathymic xenogeneic cells and intravenous cobra venom factor.

Permanent tolerance to an experimental cardiac allograft can be achieved by pretransplantation intrathymic inoculation of donor-specific lymphoid cells. We studied the effects of intrathymic inoculation of xenogeneic cells and intravenous cobra venom factor in a rodent model of cardiac xenotransplantation. Lewis rats underwent intraabdominal heterotopic heart transplantation with Syrian hamster donors. In untreated animals, mean graft survival time was 3 days. Five rats had 1 ml of antilymphocyte serum administered intraperitoneally. One day later, 2.5 x 10(7) hamster spleen cells were inoculated into the thymus under direct vision. Twenty-one days after antilymphocyte serum was given, heterotopic heart transplantation with a hamster donor was carried out. In all cases, rejection was accelerated and occurred between 20 minutes and 1 day after transplantation. Mean graft survival time was 5.2 hours (p < 0.0001 versus control). Six animals treated with antilymphocyte serum and intrathymic xenogeneic cells had 0.5 ml of cobra venom factor, a complement antagonist, administered intravenously 3 hours before transplantation and every other day thereafter. Mean graft survival was 3 days, which was not different from the response of naive animals. Animals treated with antilymphocyte serum only had no prolongation of graft survival (mean survival time 3 days, p = not significant). Animals treated with cobra venom factor alone (n = 5) before transplantation and on alternate days subsequently had mild graft prolongation with a mean survival time of 4 days (p = 0.0133). In contrast to experimental allograft models, intrathymic inoculation of xenogeneic cells produces hyperacute rejection in these naturally concordant species. The administration of cobra venom factor abrogates the hyperacute response, but the combination of cobra venom factor and intrathymic inoculation does not produce long-term graft survival.

Animals↗
PubMed1992

Leisure time physical activity: are there black/white differences?

BACKGROUND: Behavioral risk factor surveillance survey data collected during 1984 and 1985 in South Carolina were analyzed. METHODS: This article is based on telephone interviews conducted with 2,005 individuals (431 black, 1574 white), mean age, 45.1 years, selected by random-digit dialing. Information on the type, frequency, and duration of leisure time physical activity was used to estimate leisure time energy expenditure (kcal/week) averaged over the previous month. The median level of leisure time energy expenditure differed significantly (all P less than 0.001) by gender (men = 741, women = 421), age (six categories; youngest, 18-29 years = 780; oldest, 70+ = 301), annual household income (four categories; lowest, less than or equal to $10,000 = 300; highest, greater than $35,000 = 870), body mass index (kg/m2, less than or equal to 24.1 = 601, greater than or equal to 30.1 = 180), and race (black = 301, white = 601). RESULTS: Leisure time energy expenditure generally decreased with increasing age and body mass index and increased with increasing levels of education and income among all race/gender groups. Logistic regression analyses revealed that after adjustment for gender (if applicable), age, income, and body mass index, the variable race made a statistically significant contribution to the model, in the total sample (P less than .03) and for women P less than .001), but not for men. CONCLUSIONS: Our results suggest that blacks living in the South, particularly black women, have lower levels of leisure time physical activity compared with their white counterparts after control for several important confounders.

Adolescent↗
PubMed1991

Estimating prediction equations in repeated measures designs.

Experimental designs with repeated measures allow response patterns over time (or dose) to be modelled and compared between different homogeneous groups. Issues in data analysis often focus on the pattern of variation of the repeated measures, the appropriateness of a univariate or multivariate analysis, and the shape of the response pattern. An aspect of analysis that is often of equal importance is the development of a regression model for response once the pattern has been characterized. Analysis of variance or multivariate growth curve results often do not include easily interpretable regression equation estimates that can be used for prediction. We present methods and tables that permit simple construction of such predictive equations for repeated measures designs when response is modelled as a polynomial over time with univariate or multivariate analyses.

Exercise↗
PubMed1990

Atypical myocardial infarction and hypertension: an inner city experience.

The clinical features of 304 patients with acute myocardial infarction with and without hypertension were studied retrospectively. This inner city population consisted of 172 (57%) males and 132 (43%) females; 155 (51%) patients were black, 88 (29%) Hispanic, and 61 (20%) white by self-identification. Hypertension (greater than or equal to 160/95 mmHg) was present on admission in 46% (139) of patients. Typical ischaemic chest pain was the most common presenting symptom and occurred with a similar frequency in patients with and without hypertension. However, the group with hypertension consisted of proportionately more females than males, more frequently had previously diagnosed hypertension and congestive heart failure, and more often presented with shortness of breath and pulmonary oedema. The racial distribution, mean ages, prevalence of angina, previous myocardial infarction, diabetes, smoking, family history of cardiovascular disease, type of myocardial infarction, peak creatinine phosphokinase, plasma cholesterol, and mortality rates were similar in both groups. Thus, female sex, history of hypertension, history of congestive heart failure, and pulmonary oedema characterised patients with compared to those without hypertension. These findings suggest that the higher mortality rate observed in hypertensives during follow-up after myocardial infarction may be due, at least in part, to more severe underlying left ventricular dysfunction.

Aged↗
PubMed1989

Clinical features of patients with acute myocardial infarction presenting with and without typical chest pain: an inner city experience.

The clinical features of an inner-city population of 304 patients presenting with acute myocardial infarction (MI) with and without typical chest pain, were studied retrospectively. This population consisted of 172 men and 132 women; 155 (51%) were black, 88 (29%) hispanic, and 61 (20%) white, by self-identification. Typical ischemic chest pain was the presenting symptom in 85% (258); 15% (46) presented with nonchest symptoms, most frequently shortness of breath, abdominal pain, and dizziness. But the frequency of such nonchest symptoms was similar in both groups. When patients were grouped by the presence or absence of chest pain, the proportions of those without chest pain were significantly higher for blacks (22.7%) than hispanics (9.1%, P = 0.001) or whites (4.9%, P less than 0.01). Patients without chest pain also had higher admission systolic (P less than 0.01) and diastolic (P less than 0.01) blood pressures and more frequent histories of congestive heart failure (P less than 0.05), and more often presented with pulmonary edema (P = 0.001) than those with chest pain. Both groups were similar in age, sex, history of hypertension, and presence of hypertension on admission, defined as greater than or equal to 160/95 mmHg, prevalence of diabetes, history of smoking, previous MI, type of MI, history of angina, and mortality rates. Patients without chest pain were characterized by black race, history of congestive heart failure, elevated blood pressure and pulmonary edema than those with typical ischemic chest pain. Thus significant delays in the diagnosis and treatment of this important clinical entity may be reduced by alerting clinicians to these features and by educating selected patient groups.

Aged↗
PubMed1975

Problem oriented medical records: their impact on staff communication, attitudes and decision making.

A comparative, two-stage between hospital study involving university rehabilitation centers was undertaken to evaluate the impact of the problem oriented medical record (POMR) on staff communication, attitude change and decision making. Staff characteristics varied from one center to another. The semantic differential component of the project did not reveal any change due to the POMR in the staff perception of the medical record, the health care team or the various health professions. However, team function with respect to the management of specific patients improved in the centers which implemented the POMR during the time period of the project.

Attitude of Health Personnel↗
PubMedDate not supplied

Normalization of maximal cardiovascular variables for body size in premenarcheal girls.

Previous studies have indicated the importance of allometric scaling of VO2max for body size. However, no information is available on adjusting maximal cardiac output (Qmax) and stroke volume (SVmax) for body dimensions. The allometric exponent b was determined for the equation Y = aXb (where Y is the physiological outcome and X is the anthropometric variable) for VO2max, Qmax, and SVmax relative to mass, height, and body surface area (BSA) in 24 premenarcheal girls (mean age 12.2 years) during cycle testing. Values for b were 1.08 and 1.05 for BSA relative to Qmax and SVmax, approximating that of 1.0 using the traditional ratio standard (cardiac index and stroke index). Exponents of body mass relative to VO2max, Qmax, and SVmax (0.55, 0.55, and 0.59, respectively) eliminated the effects of body size, but the ratio standard (M1.0) did not. In this group of subjects, use of the ratio standard BSA was an appropriate means of adjusting maximal values of Q and SV for body size.

Body Constitution↗