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Biomedical subjects

F M Kendall

Publications and source records attributed to F M Kendall.

At least 37 records · Page 2Linked to original sources
PubMed1977

GI motor inhibition associated with acute exposure to methyl methacrylate vapor.

A mixture of monomeric methyl methacrylate vapor in air was delivered into the breathing air of chloralose-urethan anesthetized dogs. Fixed length exposures to 2000-ppm doses of the vapor resulted in a transient drop in arterial blood pressure and a marked inhibition of ongoing GI motor activities. Motor inhibition always continued for a variable time (approximately 10-15 min) subsequent to the cessation of methyl methacrylate vapor administration. This inhibitory response was not blocked by bilateral vagotomy, spinal transection, splanchnectomy, or the intravenous administration of tetraethylammonium chloride. Another series of experiments determined that the administration of blood from a dog receiving methyl methacrylate vapor produced GI motor inhibition in another dog not connected to the experimental gas mixture. Therefore, it is concluded that, aside from any reflex effects produced, methyl methacrylate vapor in sufficient concentration probably exerts a direct inhibitory effect upon GI smooth muscle that is mediated by the cardiopulmonary systems.

Aerosols↗
PubMed1977

GI pharmacology of polyethyleneimine II: motor activity in anesthetized dogs.

The effects of orally and intravenously administered doses of polyethyleneimine were observed in 18 chloralose-urethan-anesthetized dogs. Polyethyleneimine produced an initial augmentation of rhythmic segmenting gastric antral contractions, a copious flow of gastric mucus, increased segmenting and propulsive activities of the small and large intestines, and occasional micturition and defecation. The gastric corpus and fundic regions became relaxed and enlarged. These events were associated with the prompt appearance of retching. The retching response to oral administration could only be abolished by bilateral vagotomy or bilateral sympathectomy. The skeletal muscle component of retching was blocked by tubocurarine. Intravenous administration of chlorpromazine blocked the retching response and gastric corporal atonia to either intravenous or oral doses of polyethyleneimine. Either oral or intravenous administration of polyethyleneimine produced no detectable changes in the lead II ECG but was associated with marked transient reductions in both mean and pulsatile arterial blood pressures. These depressor effects showed clear tachyphylaxis. In all cases where GI effects were noted, respiration was augmented and erratic in a manner associated with the retching responses.

Animals↗
PubMed1977

Multiparameter geometric and densitometric analysis of the G0-G1 transition of WI-38 cells.

Automated image analyses were performed using Feulgen stained smears of WI-38 cells that were either confluent, or that had received a nutritional stimulus to proliferate 3 hr before collection. These experiments show that it is possible to observe changes in morphometric and densitometric parameters of nuclei that correlate with structural and functional differences in isolated chromatins from quiescent G0 and proliferation G1 cells that have been demonstrated by other means. Scatter plot analyses of the data indicated the presence of nuclear images from the stimulated G1 population that had the same deoxyribonucleic acid content as the confluent G0 cells, but had greater areas, perimeters and horizontal projections and smaller mean free paths, form factors, and average optical densities. Multiparameter cluster analysis permits, even minimally, an objective, model-independent identification of G0 from G1 cells that present an increased nuclear dispersion (i.e., lower average optical density) systematically accompanied by increased nuclear convolution (i.e., lower form factor), both compatible with the reported increase in available binding sites with respect to G0 cells.

Autoanalysis↗
PubMed1977

The occlusive competence of the duodenal orifice of the canine pancreatic duct.

Observations by scanning electron microscopy indicate that the mucosa of the terminal part of the major pancreatic duct of the dog is organized into numerous, highly convoluted folds. The individual mucosal cells are tall, columnar and studded with numerous microvilli. These folds are highly vascularized. The intraluminal administration of bethanechol and norepinephrine is associated with subsequent increases and decreases of mean opening pressures. Mean opening pressures were not observed to be associated with autonomic nervous activity that was unaccompanied by changes in systemic arterial pressure. It is concluded that the terminal portion of the canine major pancreatic duct probably acts as a passive valve, the occlusive competence of which is influenced by the status of the vasculature of the lining mucosa in this region.

Animals↗
PubMed1977

A cilia-bearing cell system in the intrahepatic bile ductules of the rat.

A scanning electron microscopic investigation of the luminal surface of the intrahepatic bile ducts of the rat has been performed using tissue prepared by critical point drying. Results of these studies have demonstrated that intrahepatic bile ducts of the rat are composed of cells, the luminal surface of which contains either microvilli or numerous long cilia. It was suggested that these cilia play an important role in tissue function, particularly in the propulsion of hepatic bile.

Animals↗
PubMed1976

A functional description of the canine choledochoduodenal flutter valve.

Forward- and reverse-opening pressures of the choledochoduodenal junction were measured in anesthetized, vagotomized dogs. Mean reverse-opening pressures were found to be significantly greater in most cases including those following the intraductal administration of vasoactive agents which are known to significantly influence mean forward-opening pressures. The polypeptides CCK-PZ and CCK-C8 were ineffective in reducing mean forward-opening pressures regardless of the route of administration. Previously published observations have indicated that mean forward-opening pressures are also unaffected by nervous activity. It is concluded that the canine choledochoduodenal junction possesses the physical and functional properties of a passive flutter valve during duodenal relaxation.

Animals↗
PubMed1975

Technique for assessment of local effects of substances found in bile upon opening pressure of choledochoduodenal junction.

An assessment of the localized influences of various chemicals found in bile was made by applying them to the interior of the canine choledochoduodenal junction. Test agents were isolated by air bubbles and introduced into the terminal lumen of the intramural portion of the common bile duct via the pressure measurement catheter; they remained in the duct for approximately 1.5 min. The system was flushed and opening pressures were then measured. Responses were measured in terms of alterations in ductal opening pressures generated by a linear pressure ramp. Histamine, serotonin, and bethanechol markedly increased ductal opening pressures, whereas epinephrine and norepinephrine decreased opening pressures. None of the agents affected either cardiovascular or small intestinal motor activity in the vicinity of the sphincter when administered in the manner. The results suggest that the presence in bile of certain neurohumoral transmitters and neurohumoral-like agents may directly affect the canine choledochoduodenal sphincter function.

Animals↗
PubMed1975

The mucosal lining of the intramural common bile duct as a determinant of ductal opening pressure.

Microanatomical evidence is presented which shows that the lumen of the intraduodenal portion of the common bile duct is almost completely filled by folds of a highly vascularized mucosa in the dog, cat, rabbit, and human. These folds are most apparent near the intraduodenal ductal orifice, where they almost completely occlude the lumen. Physiological data are presented which indicate that changes in systemic arterial blood pressure are associated with changes in the opening pressures of the choledochoduodenal junction of the cat and dog, which vary in the same direction. Experimental results indicate that bile duct opening pressures of these two species are increased by the intraductal administration of histamine and reduced by the intraductal administration of norepinephrine. A histological examination of the intraductal mucosal folds in this area, subsequent to the administration of the elevating agent, revealed a marked presence of vascular engorgement. It is concluded that the most significant determinant of changes in ductal opening pressures in the cat and dog is probably the state of the mucosal vasculature of the terminal portion of the common bile duct.

Animals↗
PubMed1975

A demonstration of microvilli on the luminal surfaces of epithelial cells of the canine extrahepatic biliary tract.

Micromorphologic evidence is presented which indicates that in the dog the lining epitheliums of the intramural portion of the common bile duct and proximal part of the cystic duct are organized into convoluted folds. The mucosal lining of the extramural portion of the common bile duct appears to contain simple crypt structures. The mucosal surface of the hepatic duct is characterized by parallel ridges, longitudinally aligned with the long axis of the duct. The epithelial cells of the entire canine extrahepatic biliary tree present a topographic-dome shaped appearance, and their luminal surfaces are densely covered with microvilli.

Animals↗