PubMed Health⌕ Search

Biomedical subjects

R L Robinson

Publications and source records attributed to R L Robinson.

At least 37 records · Page 2Linked to original sources
PubMed1993

Selective conservatism in the management of penetrating abdominal bull-gore injuries.

In a retrospective analysis it was found that not all patients with penetrating bull-gore injuries of the abdomen need exploration by formal laparotomy. A policy of selective conservatism was followed in the management of 18 out of 20 patients with bull-gore injuries of the abdomen in whom peritoneal breach was established either on presentation or by digital exploration of the wound. Formal laparotomy was reserved for specific clinical indications. Out of the 18 cases, 14 (78 per cent) were successfully treated non-operatively with wound excision, simple closure of the wound, and careful repeated clinical evaluation. There was no mortality in this group. Four cases (22 per cent) were explored; three of these had indications for exploration on presentation and the fourth was explored 4 days after admission. The latter was the only death that occurred in the series; the cause of death was probably pulmonary embolism. Omental and/or bowel evisceration occurred in 11 out of 18 cases (61 per cent). However, this was not considered an indication for exploration and all 11 cases were treated by simple replacement of omentum or bowel into the abdominal cavity. Penetrating abdominal bull-gore injuries can be managed safely by a policy of selective conservatism, reserving formal laparotomy for specific clinical indications.

Abdominal Injuries↗
PubMed1987

Opossum adrenal medulla: II. Differentiation of the chromaffin cell.

The ultrastructure of the opossum adrenal medulla was examined in its postnatal development. Maturation of chromaffin cells and genesis of chromaffin vesicles were of particular interest. The primitive sympathetic cell was seen to contain few organelles with no apparent polarity. Initial pheochromoblasts contained more organelles with some polarity. Endoplasmic reticulum and the Golgi complex increased as the pheochromoblasts matured, which suggested increased synthetic activity. Structures resembling Golgi/endoplasmic reticulum/lysosome (GERL) systems were seen in the pheochromoblasts. It is suggested that some of the components of the chromaffin vesicle may be processed by the GERL while others come directly through the Golgi complex. It is stressed that the developing pheochromoblast in the opossum presents an interesting model in which to study the genesis of the chromaffin vesicle.

Adrenal Medulla↗
PubMed1985

Altered catecholamine contents in vascular and nonvascular tissues in genetically hypertensive rats.

We have measured the catecholamine (CA) contents in hearts, mesenteric vasculature, abdominal aorta, inferior vena cava, vasa deferentia and salivary glands from genetically hypertensive rats (SHR) and normotensive Kyoto-Wistar rats (WKY). We noted differences between the norepinephrine (NE) contents of individual tissues from SHR and WKY rats and have used two different analytical procedures for the measurement of NE to confirm these differences. Comparisons between tissue contents of NE in SHR and WKY rats indicated a greater content of NE in the following tissues from the SHR: heart, mesenteric artery, abdominal aorta, inferior vena cava and vasa deferentia. A modest elevation of NE [but not epinephrine (E)] was observed in adrenal glands from SHR rats. The NE contents of salivary glands from SHR and WKY rats were indistinguishable from each other. The results suggest that there may exist a generalized increase in NE contents in the peripheral vasculature of SHR rats. Furthermore, this increase is also present in the vasa deferentia, but not the salivary gland. The results draw attention to altered concentrations of NE in vascular and selected nonvascular tissues in the SHR.

Adrenal Glands↗
PubMed1985

Sensitivity changes in the smooth muscle of the guinea-pig isolated vas deferens after treatment of animals with 6-hydroxydopamine.

Postjunctional supersensitivity of the smooth muscle of the guinea-pig vas deferens induced by denervation, decentralization and treatment of animals with reserpine has been attributed, in part, to a partial membrane depolarization (8-10 mV) resulting from reduced electrogenic Na+,K+-pumping activity. This study was undertaken to characterize sensitivity changes which occur after treatment of animals with 6-hydroxydopamine (100 mg/kg + 250 mg/kg i.v., 1 day apart). Seven days after the second injection, concentration-response curves for isometric contractile responses to norepinephrine, methoxamine, acetylcholine and histamine were shifted 40.6-, 1.7-, 3.6- and 2.7-fold, respectively, to the left of control; however, the sensitivity to KCl was not increased, which contrasts with the results after denervation, decentralization and reserpine treatment. Ouabain (10(-5) M) produced 1.8- and 1.3-fold leftward shifts of the KCl concentration-response curves in tissues from control and 6-hydroxydopamine-treated animals, respectively. The pronounced effect of ouabain in tissues from treated animals may be an indication that 6-hydroxydopamine treatment does not result in as much inhibition of electrogenic Na+,K+-pumping, and resultant membrane depolarization, as other methods which induce supersensitivity of the guinea-pig vas deferens.

Acetylcholine↗
PubMed1983

Effects of short-lasting and long-lasting blood pressure changes on the release of endogenous catecholamines in the hypothalamus of the conscious, freely moving rabbit.

In anaesthetized rabbits guide cannulae were stereotaxically inserted into the anterior hypothalamic area and into the posterior hypothalamic nucleus. Additionally, catheters were inserted into the carotid artery and the jugular vein. Some days after the operation push-pull cannulae were inserted through the guide cannulae into the hypothalamic regions of the conscious, freely moving animal. The areas were superfused with artificial CSF and the release of the endogenous catecholamines dopamine, noradrenaline and adrenaline was determined in the superfusates. In the two hypothalamic regions the resting release of the catecholamines rhythmically varied with time at approximately 70 min cycles. A rise in blood pressure induced by the intravenous injection of noradrenaline or tramazoline enhanced the rates of release of the catecholamines in the anterior hypothalamic area. A fall of blood pressure elicited by the intravenous injection of nitroprusside or chlorisondamine decreased the release of the catecholamines in this hypothalamic area. The changes in blood pressure coincided with the changes in the rates of release of the catecholamines in the anterior hypothalamic area. These and previous results concerning changes in the release of endogenous catecholamines in the posterior hypothalamic nucleus also indicate that in the conscious, freely moving rabbit changes in blood pressure lead to counteracting alterations in the release of catecholamines in the two hypothalamic regions.

Animals↗
PubMed1982

Bilateral secretory responses of the adrenal medulla during stimulation of hypothalamic or mesencephalic sites.

Bilateral secretion of epinephrine and/or norepinephrine from adrenal medullae occurred in 76% of cats studied following unilateral electrical stimulation of sites in the hypothalamus or rostral mesencephalon. Responses were generally greater on the ipsilateral side. In most experiments, epinephrine alone or both epinephrine and norepinephrine outputs were increased. In only two experiments norepinephrine output was increased. Stimulation of most hypothalamic sites that evoked bilateral secretion was accompanied by an increase in blood pressure. Stimulation of effective sites in the mesencephalon was not generally accompanied by blood pressure changes.

Adrenal Medulla↗
PubMed1982

Release of endogenous histamine in the hypothalamus of anaesthetized cats and conscious, freely moving rabbits.

The hypothalamus of anaesthetized cats and conscious, freely moving rabbits was superfused with CSF through double-walled, push-pull cannulae and the release of endogenous histamine was determined in the superfusates by a radioenzymatic assay. In the posterior hypothalamic area of the anaesthetized cat, the rate of release of endogenous histamine varied rhythmically; phases of high rate of release appeared at 60 min cycles. The release of histamine was increased by electrical stimulation of the superfused area, as well as by hypothalamic superfusion with potassium-rich CSF. In the conscious rabbit, the anterior hypothalamic area and the posterior hypothalamic nucleus were superfused simultaneously. In both regions, the resting release of histamine varied rhythmically at approximately 70 min cycles. Phases of high or low-rate of release in the anterior hypothalamic area coincided with the corresponding phases in the posterior hypothalamic nucleus. The rhythmic release of endogenous histamine in the hypothalamus, as well as the ability of depolarizing stimuli to enhance the release of the amine support the idea that histamine acts as a neurotransmitter in the central nervous system.

Anesthesia↗
PubMed1978

Oxidized cholesterol bilayers. Dependence of electrical properties on degree of oxidation and aging.

Black lipid membranes made from oxidized cholesterol were examined for their specific resistance, capacitance, and physical stability, as a function of cholesterol oxidation time and of age. Membranes formed from cholesterol oxidized in n-octane were not physically stable even after 7 h of oxidation unless they were aged for at least a month. Membranes formed from cholesterol oxidized in decane and tetradecane (1 : 1) were stable immediately after 2--6 h of oxidation. Oxidation times outside this range produced unstable membranes. After 1 month storage, membranes from cholesterol solutions oxidized in decane and tetradecane from 0.75--3 h were stable. After 11 months, only the 0.75 oxidation time produced stable membranes. Storage in nitrogen retarded the aging process. After initial forming of the membrane, total membrane area and capacity increased and then stabilized, although specific capacity and resistance did not change, indicating inherent stability in the bilayer's intrinsic electrical properties. Bilayers formed soon after cholesterol oxidation had membrane capacity which ranged from 0.42 to 0.55 muF/cm2. Specific membrane resistance ranged initially from 2 . 10(6) to 37 . 10(6) omega/cm2 in 0.2 M NaCl with lower resistances in the more oxidized membranes. With aging, membrane capacity decreased gradually over 11 months to values approaching 0.1 muF/cm2 indicating membrane thickening. Membrane resistance ordinarily decreases with storage time. The rate of these changes with age is dependent on the extent of initial cholesterol oxidation and subsequent oxidation, with long term stability best in the least oxidized membranes.

Cholesterol↗
PubMed1976

Is it possible to educate a psychiatrist?

The author, who served as Executive Secretary and Editorial Consultant to the Conference on Education of Psychiatrists held in June 1975, presents here in some of the major findings, concerns, and dilemmas encountered by the conferees as they considered the current status of psychiatric education and the course it should take in the coming decade. The fundamental problem is that there is no firm consensus defining what a modern psychiatrist is or what he sould be. Basically the complete psychiatrist sits on a three-legged stool of biological, psychological, and social science. But the stool wobbles because the legs are of different length and thus far no one has been able to even them out.

Community Psychiatry↗
PubMed1975

Synthesis, storage and drug-induced release of atp-8-3h in the perfused bovine adrenal gland.

The perfused bovine adrenal gland was able to take up and phosphorylate adenosine-8-3 H. Stimulation of the gland with carbachol resulted in a simultanious release of catecholamines, adenosine-8-3 H and labelled adenine nucleotides including a small quantity of ATP-3 H. A direct demonstration of the presence of ATP-3 H in isolated chromaffin granules was obrained by modified sucrose density gradient centrifugation. Glands were also perfused with a Ca++-Mg++-free-EDTA medium to inhibit adenosine triphosphatases. Using this medium, significant amounts of ATP-3 H and endogenous ATP were found in the effluent after drug stimulation by either Ba++ of aminophylline. Under Ca++-Mg++-free-EDTA conditions both Ba++ and aminophylline, but not carbachol, stimulated the release of catecholamines, ATP, ATP-3 H with no concomitant increase in total radioactivity. Using normal medium, Ba++ caused the simultaneous release of catecholamines and radioactivity while aminophylline only induced the release of catecholamines. Specific activity measurements of drug-released ATP indicated that the newly synthesized ATP-3 H was being released preferentially during spontaneous activity while the endogenous ATP was preferentially released after either Ba++ or aminophylline-induced secretion.

Adenosine↗