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Biomedical subjects

B L Munger

Publications and source records attributed to B L Munger.

At least 73 records · Page 4Linked to original sources
PubMed1977

Neural-epithelial interactions in sensory receptors.

The specific types of relationships that exist between sensory nerve fibers and the associated epithelial cells have been reviewed in a variety of sensory systems. In many sensory systems, perhaps most, specificity of terminal epithelial element provides a degree of specificity to the cytologic pattern of the terminal receptor. We can see examples of such interaction, not only in the case of intraepithelial nerve fibers where nerves tend to be associated with Merkel cells, but also in the case of corpuscular receptors, both of these being examples of mechanosensory systems. Equivalent types of specificity are present within the special senses, where a specific receptor cell can be described. These findings strongly suggest that specificity in the peripheral nervous system is the rule rather than the exception, a thesis proposed over a hundred years ago by F. Merkel.

Animals↗
PubMed1976

Scanning microscopy of pituitary vascular casts.

Vascular casts of the pituitary-median eminence complex from seventeen adult female rabbits were examined with the scanning electron microscope. The results of this study confirm the presence of a single capillary bed common to the entire neurohypophysis. Arterial supply to the rabbit pituitary is only to the neurohypophysis. A direct supply to adenohypophysis was not found. Within the median eminence there are an external and internal capillary plexus. The internal capillary plexus is directed toward the infundibular recess of the third ventricle. It does not receive a direct arterial supply but derives its blood supply from the external plexus before draining to the adenohypophysis. Vessels of the posterior median eminence are confluent with vessels of the infundibular stem. On the basis of these studies, it is proposed that the entire neurohypophysis, not simply the median eminence, serves as the final common pathway to the glandular pituitary. It is also proposed that in the median eminence, vessels are organized to deliver blood containing hypothalamic releasing and inhibiting hormones as well as posterior lobe neural hormones (antidiuretic hormone and oxytocin) to the ventricular surface for subsequent transport to cerebrospinal fluid and distribution to the brain.

Animals↗
PubMed1976

Diabetes mellitus in the guinea pig.

Spontaneous diabetes mellitus has been documented in a colony of guinea pigs. The contagious nature of the disease has been verified, but the nature of the infectious agent is not known. Animals from the original colony or animals exposed to the colony with normal glucose tolerance tests (GTT) became diabetic, as evidenced by elevated one- and four-hour GTT values, and in most cases have significant glycosuria. The severity of pathologic changes in the pancreatic islets parallel, in general, the severity of the clinical symptoms (glycosuria and abnormal GTT). Those animals with severe glycosuria and elevated FBS as well as one- and four-hour GTT values had the most pronounced degranulation and most prominent cytoplasmic inclusions in islet B cells. The severity of scarring in the islets can be correlated with the duration of the overt diabetic state. The other clinical parameters of note were elevated serum triglycerides, normal serum but elevated aortic cholesterol, and absence of ketonemia or ketonuria. The reproductive capacity of diabetic females was compromised. While the clinical manifestations are mild or variable, the presence of significant islet pathology is reminiscent of human juvenile diabetes mellitus. These findings lend support to the concept that infectious and/or immune mechanisms could be operative in the etiology and pathogenesis of human diabetes mellitus.

Animals↗
PubMed1975

Exocrine pancreatic dysfunction in guinea pigs with diabetes mellitus.

In this study, 37 guinea pigs were classified, on the basis of histologic examination of the pancreas, into three categories: nondiabetic, latent diabetic, and overt diabetic. In order to compare the exocrine pancreatic function in these three groups of animals, pancreatic secretion was collected from each animal following an intravenous infusion of secretin and pancreozymin. Pancreatic enzyme activity, bicarbonate concentration, and the total volume of pancreatic secretion were all significantly decreased in guinea pigs with overt diabetes, but not in those with latent diabetes mellitus. Pancreatic histologic changes characteristic of both latent and overt diabetes were beta-cell hyperplasia and generalized fatty degeneration of the acini. Only the animals with overt diabetes showed total degranulation and severe vacuolation of theta-cells. The same type of exocrine pancreatic dysfunction observed in guinea pigs with spontaneous overt diabetes mellitus is found in human diabetics, and is particularly common in the juvenile type. The guinea pig, therefore, appears to be a suitable animal model for the study of human juvenile diabetes mellitus.

Amylases↗
PubMed1975

The effect of different methods of protecting the myocardium on lysosomal activation and acid phosphatase activity in the dog heart after one hour of cardiopulmonary bypass.

The present study was undertaken to determine the involvement of cardiac lyososomes in injury to the myocardium after cardiopulmonary bypass. Twenty conditioned mongrel dogs, weighing 15 to 18 kilograms, were fasted overnight, anesthetized with sodium pentobarbital (30 mg. per kilogram), intubated, and maintained on positive-pressure ventilation. The femoral artery and femoral vein were cannulated for pressure measurements. After median sternotomy, intravenous heparin was administered (3 mg. per kilogram) before the aorta and the superior and inferior venae cavae were cannulated for bypass. Bypass was instituted with a Travenol modular pump and a Bentley pediatric bubble oxygenator and heat exchanger. The ultrastructural effects on the myocardium and the acid phosphatase activity in the left ventricle were compared in dogs exposed to bypass for 1 hour with varying types of myocardial support: perfusion of the coronary arteries, normothermic ischemic arrest, or selective cardiac hypothermia. The morphology of control hearts and hearts fixed after 1 hour of coronary perfusion were similar. The distribution and structure of subcellular lysosomes were the same and showed identical patterns of acid phosphatase activity. Normothermic ischemic arrest was associated with a loss of glycogen stores, disrupted sarcoplasmic reticulum and T tubules, vacuolization and decrease in matrix density of mitochondria, and separation of the intercalated discs. Lysosomal activity was absent except for occasional residual bodies in the nuclear pole zone of the myocardial cells. Selective cardiac hypothermia produced results superior to those from normothermic ischemic arrest. Although these hearts showed proliferation of the lysosomal compartment, the organelles responsible for excitation-contraction coupling were spared.

Acid Phosphatase↗