Rexford E. Carrow

Effects of physical training on the histochemistry and morphology of ventral motor neurons

Abstract Ventral motor neurons of sedentary and chronically exercised rats were studied histochemically for acid phosphatase (A.Pase), glucose-6-phosphate dehydrogenase (G-6-PD), and malic acid dehydrogenase (MDH) activity. Seventy-two male Sprague-Dawley rats, 100 days of age, were placed into three groups. The control group (A) was housed in sedentary cages. The animals of a sedentary-forced group (B) were placed into sedentary cages, but were exercised by swimming 30 min per day with a weight equalling 4% of their body weights attached to their tails. A voluntary-forced group (C) was housed in cages equipped with voluntary exercise wheels and received two 30 min forced exercise swims per day. The animals of this group swam with weights equal to 4% of their body weights. The duration of the exercise treatment was 52 days. Animals of group B, which had been subjected to a moderate, but intermittent exercise program, demonstrated a diminished glucose-6-phosphate dehydrogenase staining and an increased acid phosphatase reaction. This group also experienced the greatest difficulty in coping with the exercise program. The animals of group C, which had been subjected to a more severe but continuous exercise treatment, showed an intense G-6-PD reaction in their neurons along with a diminished A.Pase reaction. Malate dehydrogenase staining of motor neurons was greatest in the rats that were voluntarily active and forced to exercise, and was lowest in the sedentary animals.

Effects of an anabolic steroid and sprint training on selected histochemical and morphological observations in rat skeletal muscle types

SummaryThe effects on selected histochemical and morphological parameters of anabolic steroid administration and of high-intensity sprint running, separately, and in combination, were studied in young adult male rats. Dianabol (methandrostenolone) 1 mg/day for 8 weeks had no significant effects on phosphorylase or glycogen staining intensities and on fiber area in skeletal muscles of either trained or sedentary animals. The program of sprint training resulted in significantly decreased intensities of phosphorylase in all ten regions of the gastrocnemius, plantaris, and soleus muscles that were studied. Glycogen localization was significantly increased with training in five regions of the gastrocnemius and plantaris muscles which contained predominantly fast-twitch fibers. No changes in fiber area occurred with the training program. We conclude from these results that (a) normal androgen levels in young, healthy male animals are sufficiently high so that the intake of large doses of anabolic steroid does not result in the stimulation of glycogen metabolism or hypertrophy of skeletal muscle; (b) the changes induced by high-intensity, short-duration sprint training suggest that the existing glycolytic capacity of muscle is adequate to supply the muscles energy needs even during the stress of very strenuous exercise, and that more fast-twitch fibers were recruited by the exercise regimen than slow-twitch fibers.

Effects of swimming on dystrophic Syrian hamster heart.

Morphological and histopathological heart changes were determined for sixteen dystrophic Syrian hamsters (B10 14.6 strain) and sixteen normal hamsters. Eight animals were randomly assigned to each of the following groups: dystrophic swim (DYS-SWM), dystrophic sedentary (DSY-SED), normal swim (NOR-SWM), and normal sedentary (NOR-SED). The daily swimming program consisted of an initial 30-minute swim which was gradually extended to 60 minutes by the end of eight weeks. Weights up to 3% body weight were attached during swimming to increase the work load. Sedentary animals received no experimental treatment. Four animals in each group were sacrificed at 4 and 8 weeks after the initiation of treatments. In comparison with the two groups of sedentary animals, the NOR-SWM group had a greater heart weight/body weight ratio at both 4 and 8 weeks (P less than .05), while the DYS-SWM group had an increased ratio only at 8 weeks (P less than .05). Subjective histopathological evaluation of heart lesions showed that the DYS-SED group had many large areas of inflammatory reaction with infrequent diffuse areas of calcification. In contrast, the DYS-SWM group had fewer and smaller areas of inflammatory reaction with moderate amounts of calcification.

Problem-based anatomy for surgical residents

Graduating medical students who enter surgery residencies frequently have limited anatomic experiences during their undergraduate training. Throughout the 5 years of surgical training residents are exposed to the anatomy as it relates to the operative procedures performed. Frequently, however, many of the complex anatomic areas of the body escape the experience of a surgery resident in training. The American Board of Surgery requires that surgeons have comprehensive experience with problems located in the head and neck, chest, abdomen, pelvis, and extremities. In an effort to provide an experience in the critical anatomic areas, the Michigan State University (MSU) Integrated General Surgery Residency developed a problem-based anatomy course that focuses on some of the most difficult anatomic areas in which surgeons are expected to provide lifesaving procedures.A program was developed that would present a series of clinical scenarios focusing on critical anatomic approaches and related structures in the head and neck, thorax, abdomen, pelvis, perineum, upper extremity, and lower extremity. The program involved 61 individual clinical scenarios, each requiring specific dissections. The course is directed by a surgeon and anatomist, with the discussion focused entirely on surgical approaches, related anatomic structures, and the options of therapy. The course has been taught for 4 years with great success. The program is now being extended to all affiliated general surgery residencies in the MSU system.A problem-based anatomy course has been developed that addresses many of the complex anatomic areas in which surgeons are expected to provide safe operative intervention. A problem-based approach has provided opportunities for surgical residents to consider operative approaches necessary to perform procedures in a safe, competent manner. The success of this approach would lend credence to expanding its utility to other specialties and even medical student training. (Curr Surg 57:377-380. Copyright 2000 by the Association of Program Directors in Surgery.)

Histochemical and morphological observations on rat myocardium after exercise.

Effects of seven levels of chronic physical activity on the metabolic and morphologic characteristics of left ventricular myocardium of adult male albino rats were investigated.Treatments included sedentary control; voluntary running; short-duration, high-intensity running; medium-duration, moderate-intensity running; long-duration, low-intensity running; electric stimulus control; and endurance swimming. Excluding the controls, the animals were trained 5 days per week for 8 consecutive weeks. Food and water were providedad libitum to them. Fifty-six animals comprised the final sample.Histochemical techniques were used to evaluate the relative glycogen, fatty acid, SDH and LDH concentrations in the cardiac fibers. Each stain was measured objectively, using a photometer. A Hematoxylin and Eosin stain was employed to rate morphologic features. These sections were evaluated subjectively on the basis of presence or absence of lesions.Physical training for 8 weeks was sufficient to produce metabolic adaptations in the rats. The trained animals gained 37.4 % less body weight than did the sedentary controls (P < 0.05). However, neither histochemical nor morphological changes had occurred to the hearts of these animals consequent to the 8 weeks training programs. Apparently, the myocardial tissues examined, from the trained animals, contain the enzymes, SDH and LDH, and the substrates, glycogen and fatty acids, in amounts greater than that needed to cope with the exercise stress afforded by these training programs.

Effects of Prepubertal Forced Exercise Upon Postpubertal Organ and Body Weights of Female Rats.

Abstract One-hundred-fifty female rats were used in this study of the immediate and residual effects of prepubertal exercise upon organ and body weights. Animals were randomly assigned to 3 initial treatment groups: sedentary (S), voluntary (V), and voluntary plus forced exercise (V+F). Forced exercise consisted of 35 daily 30-min. swims with a tail weight of 2% of body weight. Two treatment periods were given, one just before puberty and another after 165 days of intervening voluntary activity. Sacrifices occurred posttreatment I, pretreatment II, and posttreatment II. Both (V) and (V+F) animals had lower body and absolute spleen weights but higher relative adrenal, heart, and liver weights than the controls. The absolute spleen and relative adrenal differences remained pretreatment II. Posttreatment II, lower body and absolute spleen weights were noted in (V) than in (S) groups. Although several significant interactions between treatments I and II were observed, only the lower body weight of active anim...

Cardiac carnitine acyltransferase activities in exercised normal and dystrophic hamsters

Carnitine acyltransferase activities in the hearts of normal and dystrophic, sedentary and swim exercised hamsters were studied, in order to analyze the relationship between carnitine metabolism and exercise in cardiomyopathy. After 12 weeks, the mean specific activities of cardiac carnitine acetyltransferase (CAT), carnitine octanoyltransferase (COT) and carnitine palmitoyltransferase (CPT) were significantly higher in the dystrophic sedentary group, relative to the normal sedentary group (p less than 0.05). There was no significant effect of exercise on the mean specific activity of the carnitine acyltransferases, compared to the dystrophic or normal sedentary controls. Thus, the improvements in cardiac histopathology due to exercise noted previously are not associated with altered carnitine acyltransferase activity.

Separate and simultaneous effects of aerobic exercise and anxiety on myocardial damage in the rat

The purpose of this study was to determine the effects of various programs of physical activity on anxiety-related myocardial damage in rats. The anxiety-producing stress consisted of randomly distributed applications of a disturbing but nonpainful electrical shock. Physical activity consisted of long-duration, low-speed running. Three hundred and seventy-five male albino rats were randomly assigned to five comparison groups. The results show that the anxiety treatment produced marked myocardial damage. Animals preconditioned by eight weeks of exercise prior to the introduction of the anxiety treatment did not suffer as much myocardial damage as did animals that were not preconditioned. However, a group in which exercise and anxiety were introduced simultaneously had the highest incidence of myocardial necrosis. We conclude that aerobic exercise can modify the effects of a subsequent or simultaneous anxiety-producing stressful situation on the myocardium of the laboratory rat. The time at which the exercise is imposed determined the nature of the effect.