John B. Gelderd

Evaluation of blood vessel and neurite growth into a collagen matrix placed within a surgically created gap in rat spinal cord.

A complete gap of 3-4 mm was surgically created in the spinal cord of adult rats between the T8-T10 vertebral level, filled with a collagen matrix and closed with sutures. Animals were killed at weekly intervals from 14 to 42 days postimplantation. The collagen implant (CI) was evaluated for ingrowth of blood vessels and neurites using light and electron microscopic techniques. At 42 days postimplantation, 3 CI animals underwent a transection at the rostro-caudal center of the CI followed by placement of horseradish peroxidase (HRP)-impregnated filter paper between the cut ends. The number and location of HRP-labeled cells in CI animals were compared to normal animals that received a spinal cord transection at the T9 vertebral level immediately followed by placement of HRP between the cut stumps of spinal cord. Connective tissue (CT) septae, neurites and blood vessels invaded the CI from adjacent spinal neuropil and surrounding CT capsule. CI animals revealed HRP-labeled cells in the intermediolateral cell column (IML), parabrachial nuclei, locus coeruleus and red nucleus with a preponderance of labeled cells found in the IML rostral to the CI. In contrast, no IML were labeled in thoracic spinal cord rostral to HRP implantation in control animals. It was concluded that the above brainstem nuclei, which normally project axons into spinal cord, are capable of extending their severed axons into the CI following spinal cord injury and that uninjured IML cells also sprout axons into the CI.

Effects of exercise on immune functions of undernourished mice

Regular moderate exercise may modulate the response to a stressor and thus improve immune functions in conditions commonly associated with immunodepression and elevated levels of stress hormones. For example, anorexia nervosa patients, many of whom engage in regular aerobic exercise, generally have normal immune function and viral disease resistance in spite of their severe undernutrition. To test the hypothesis that exercise can prevent undernutrition-induced immunodepression, mice were fed a nutritionally complete, semi-purified diet, either ad libitum or in restricted quantities to induce 25% loss of initial weight over 3 weeks. Half the animals from each dietary group were run on a treadmill for 30 min/day, 5 days/week. Exercise had no effect on several measures of nutritional status. Spleen weight and blastogenic response to lipopolysaccharide were significantly increased by exercise in undernourished mice. In vivo antibody response to sheep red blood cells, and in vitro splenic responses to concanavalin A and phytohemagglutin were not significantly affected by exercise. Serum corticosterone level was increased by food restriction and significantly decreased by exercise in the undernourished mice. Within a treatment group there were no significant correlations between serum corticosterone level and any immune system measure. Hypothalamic concentration of uric acid was increased in food restriction groups and concentration of norepinephrine was increased in exercise groups. The results suggest that regular exercise may help prevent undernutrition-induced immunodepression, possibly through modulation of the stress response.

The effects of interleukin-1 receptor antagonist protein (IRAP) infusion following spinal cord transection in rats

A laminectomy was performed at the T5-T6 vertebral level in adult, male, Sprague-Dawley rats and the spinal cord transected with a scalpel. A group of sham animals was subjected to the same surgery without the transection step. A group of unhandled control rats was also included. A subgroup of transected animals received a subcutaneous osmotic minipump that dispensed IL-1 receptor antagonist protein (IRAP) at the transection site for 7 consecutive days. Another transected subgroup received a minipump that infused the vehicle only. IRAP-treated rats displayed a significant reduction in body temperature (p < 0.05) compared with vehicle-treated rats. The IRAP-treated rats were also less active when assessed for locomotor behavior using an HVS computerized tracking system (p < 0.01). IRAP treatment had no effect on serum corticosterone, beta-endorphin levels, Con A, PHA, or LPS-induced splenocyte mitogenesis when compared with vehicle-treated animals. However, half of the IRAP-treated animals exhibited a substantive reduction in the number of reactive astrocytes near the transection site, suggesting a possible effect of IRAP on astrocyte activation.

A preliminary study of homotopic fetal cortical and spinal cotransplants in adult rats

Neocortical and spinal tissue from a given E16-17 rat fetus were homotopically transplanted into lesion sites of adult rats which had undergone combined cortical and complete lower thoracic spinal cord lesions. Spinal cord transplants were placed either directly into the gap in host spinal cord or embedded in a collagen matrix. Animals were killed from 4 days to 8 months and tissues were processed for light microscopy. All cortical transplants survived and integrated with host brain. Many axons appeared to grow between the cortical transplant and subjacent host parenchyma. Only collagen-embedded spinal transplants survived. At 8 months, two animals underwent spinal cord transection and HRP implantation two vertebral segments rostral to the spinal cord transplantation site. Both animals revealed HRP-labeled neurons in the cortical transplants. It was concluded that 1) homotopically transplanted fetal cortical tissue can survive and may be capable of extending axons to midthoracic levels, and 2) a collagen matrix may enhance the survival of fetal tissues transplanted into a complete gap in host spinal cord.

Histochemistry of the myocardium and its vasculature in the normal rat

Coronary arteries and arterioles in the left and right normal rat ventricle were examined histochemically to determine their metabolic activities. Aerobic metabolic capacity was determined by assessin

Quantitative Studies of Reactive Events in the Site of Injury Following Transection of the Spinal Cord in the Rat

Transection of the mammalian spinal cord results in a complete and permanent loss of voluntary motor function below the level of the lesion accompanied by an equally profound sensory loss. In many phylogenetically lower animals, massive axonal regeneration occurs and often results in some degree of functional restitution, despite the presence of scar formation within the site of injury (Bernstein and Bernstein 1967), but in mammalian forms regeneration of CNS axons is considered to be minimal and abortive (Ramon v Cajal 1928). A variety of treatment methods have been employed in an attempt to promote the regeneration of axons across the transection site (Puchala and Windle 1977). These have included the implanting of grafts of fetal brain tissue, degenerated sciatic nerve or muscle into the lesion site in order to improve the environment for optimal axonal growth (Sugar and Gerard 1940), administration of adrenocorticotrophic hormones (McMasters 1962), millipore cylinders (Campbell and Windle 1960), or Piromen, a pyrogenic bacterial polysaccharide thought to enhance regeneration by preventing the formation of a dense fibrous scar following injury (Clemente and Windle 1954, Littrell 1955). Application of Piro-men seemed to increase the number of regenerating fibers as shown by morphological and electrophysiological techniques, but the animals failed to demonstrate an improvement in their sensorimotor function.

Metabolism of Coronary Vasculature in Euthyroid, Hyperthyroid and Recovering Hyperthyroid Rats: A Histochemical Study

Coronary arteries and arterioles from normal rats, from rats made hyperthyroid by administration of desiccated thyroid for 10 weeks, and from hyperthyroid rats which were then fed normal control diets for 10 weeks, were examined histochemically to determine the activity of key metabolic pathways. The primary aims of this study were to determine if the alterations in particular enzyme and substrate activities that occur in thyrotoxic rat myocardium, arteries and arterioles were reversible and would return to normal levels following cessation of the hyperthyroid state. Our results suggest that hyperthyroid rats, even after 10 weeks on the normal diet, still show some compromise in arteriolar aerobic metabolism in favor of anaerobic pathways, while coronary arteries still demonstrate little glucose-6-phosphate dehydrogenase activity. Myocardial metabolic activity approximates that of normal control animals by the end of the 10th week on the normal diet.

A Histochemical Study of the Coronary Vasculature in Euthyroid and Hyperthyroid Rats

Coronary arteries and arterioles in the left and right ventricles from normal and hyperthyroid rats were examined histochemically to determine and to compare their metabolic activities. The test animals were made hyperthyroid by administration of desiccated thyroid for 8-10 weeks. Using histochemical techniques, selected enzymes and components of key metabolic pathways were examined. These pathways included an evaluation of aerobic (oxidative phosphorylation, Krebs cycle and respiratory chain) and anaerobic metabolic capacity, hexose-monophosphate shunt activity, amounts of deoxyribonucleic and ribonucleic acids present and activity of beta-oxidation of fatty acids. Our results indicate that normal coronary arteriolar metabolism is predominantly aerobic. The findings also suggest a reduction in aerobic metabolism with an accompanying increase in anaerobic potential in the hyperthyroid coronary arterioles. Thus, during thyrotoxicosis, the coronary arterioles may partially shift from aerobic to anaerobic metabolism. Moreover, in both the normal and thyrotoxic rat heart, the coronary microvasculature appears quite stable with little cell proliferation. In contrast, both the control and hyperthyroid rat coronary arteries appear to utilize primarily anaerobic pathways, while the control and hyperthyroid myocardium seem highly dependent upon aerobic metabolism. The tremendous reduction in glucose-6-phosphate dehydrogenase activity in hyperthyroid, when compared to normal coronary arteries and some larger arterioles, implies a reduced capacity for nucleic acid and protein synthesis in the test animals.

Cytochemistry of the Blood Basophil of Bufo marinus

The morphology and cytochemistry of the blood basophil of Bufo marinus are characterized, and compared and contrasted to the basophil from several other amphibians and with the mammalian basophil. The basophil of B. marinus contains at least one type of mucopolysaccharide and an acid mu- copolysaccharide, possibly heparin, within the cytoplasmic granules. Several amino acids, but no histidine, and no lipid, occur in B. marinus basophils. Furthermore, these basophils appear devoid of hydrolytic enzymes, excepting nonspecific esterase. They do possess numerous oxidative enzymes, however, in the intergranular cytoplasm. The basophil of B. marinus is more similar cytochemically to the mammalian basophil than to the basophil of several previously studied amphibians. Considerable information regarding the morphology and cytochemistry of the mammalian blood basophil is available (Wetzel et al., 1967; Ackerman and Clark, 1971; Komiyama and Spicer, 1974; van El- ven et al., 1977). Ackerman (1963a) pre- sents an excellent review and comparison of basophil cytochemistry in several mam- malian species, including man; he also compares and contrasts the basophil with the mast cell. In contrast, although discov- ered over a century ago, the precise func- tions of the mammalian basophil remain obscure, despite its involvement to some extent in phagocytosis, allergic reactions, and delayed hypersensitivity (Stossel, 1977). Even less is known about the am- phibian basophil. Due to the fragility of the basophil, and its infrequency (1% or less) in the peripheral blood (factors which also hindered study of this cell in mam- mals) few data regarding the amphibian basophil are available. Caxton-Martins (1978) cytochemically examined the leu- kocytes in two West African anurans, Rana temporaris and Bufo regularis, but reported his findings as granulocytes, not differ- entiating among neutrophils, eosinophils, and basophils. In the newt, Notophthalmus viridescens, Cowden et al. (1964) demon- strated the presence of mucopolysaccha- ride and tyrosine in basophilic leukocytes and tissue mast cells.