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Biomedical subjects

J S Martin

Publications and source records attributed to J S Martin.

At least 91 records · Page 5Linked to original sources
PubMed1979

Evidence of reflexive beta adrenergic motor stimulation in the canine stomach and small intestine.

Studies in our laboratory have confirmed the previous observations that adequate electrical stimulation of either the left or right central vagus nerves in the dog after bilateral vagectomy produces relaxation of the stomach and small intestine. On the other hand, central vagal stimuli delivered to dogs that were either chronically reserpinized or were premedicated with the alpha adrenolytic phenoxybenzamine resulted in increased segmenting activity of these two organs. These excitatory responses were abolished by bilateral section of the sympathetic chains and could be reproduced by electrically stimulating the chains. The excitatory effects of either central vagal stimulation, peripheral sympathetic stimulation or intravenous isoproterenol administration could be abolished by dichloroisoproterenol. It was also determined that isoproterenol produced a tonic contraction of the separated muscularis mucosa which was distinguishable from a relaxation of the muscularis externa. It is suggested that a sympathetic pathway exists which is excitatory to the stomach and small intestine and that these excitatory effects are mediated by beta adrenergic neurotransmitters. The results further suggests that the beta excitatory reflex response is mediated by the muscularis mucosa as the target effector system.

Animals↗
PubMed1978

A deaf child.

Explore the source record for details and available documents.

Child Development↗
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

Thermal stimulation of the oral mucosa and nasal airway resistance.

A procedure for measuring nasal airway resistance using posterior rhinorheometry is described. Baseline nasal airway resistances +/- 1 S.D. at an airflow of 0.5 L/sec were found to be 1.077 +/- 0.683 cm H2O for inhalation and 1.359 +/- 0.792 cm H2O for exhalation. Application of either cold water (4 to 6 C) or warm water (44 to 52 C) to the oral mucosa significantly increased nasal airway resistance. Application of tepid water (26 to 28 C) did not alter nasal airway resistance significantly.

Airway Resistance↗
PubMed1977

Clinical results of photochemotherapy. The Cleveland Clinic experience.

PUVA therapy has proved to be beneficial for dermatologic conditions such as psoriasis, vitiligo, and mycosis fungoides. Attempts have been made to treat other diseases with the modality; five patients with pityriasis rubra pilaris were treated, with only a partial response noted in one. A poor to fair response was seen in treating a small group of patients with cystic acne, atopic dermatitis, and neurodermatitis. As might be expected, no response was seen in one patient with Darier's disease. At present, photochemotherapy must be viewed with cautious optimism. Strict adherence to a rational treatment approach and close longterm follow-up observations are essential for determining the safety of this modality.

Evaluation Studies as Topic↗
PubMed1977

Photochemotherapy for psoriasis.

Photochemotherapy for psoriasis combining orally administered methoxsalen and long-wave ultraviolet (UVA) light was used in 186 patients with severe psoriasis. Several different phototherapy units with various numbers of GE high-output black lights were used. Excellent (90% to 100% clear) and good (80% to 90% clear) results were obtained in 77% of the patients. The average UVA dose at clearing was between 7 and 8 joules/sq cm. The majority of patients required one weekly maintenance UVA dose of their last clearing dose (joules per square centimeter) to remain clear. Side effects and abnormal laboratory findings were minimal.

Administration, Oral↗
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↗
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

Evidence of nonvagal neural stimulation of canine gastric acid secretion.

In this study, we confirmed our original findings that central vagus stimulation is significantly associated with a subsequent increase in gastric mucus secretion. Central vagus stimulation following phenoxybenzamine hydrochloride administration was associated significantly with protracted elevations in secretory volume and titratable acid. We were unable to conclude that phenoxybenzamine itself in several pharmacologic dosages was associated with an increase in titratable acid. The acid secretory responses could be abolished by transection of the splanchnic nerves. Electrical stimulation of the peripheral part of the splanchnic nerve following administration of phenoxybenzamine was also associated with significant increases in secretory volume and titrable acidity. These secretory responses were not blocked by atropine but were diminished by burimamide. It is concluded that, in the dog, a largely heretofore unsuspected second neural pathway exists which is capable of influencing gastric acid secretion.

Animals↗