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Biomedical subjects

R Morton

Publications and source records attributed to R Morton.

At least 91 records · Page 5Linked to original sources
PubMed1981

Generalized Spearman estimators of relative dose.

In a biological assay the expected response may be transformed to a variable bounded between 0 and 1. If the transformed response is regarded as analogous to the tolerance distribution function, the mean of that distribution may be estimated for the standard and test preparations, and a simple estimator of the relative potency obtained. The special case where the identity transformation is used for a quantal response corresponds to Spearman's estimator, and our generalization has similar unbiasedness properties to that estimator. Asymptotic results are derived when the intervals between dose levels decrease and the sample of each dose level simultaneously increases. These results are evaluated for the case with equal sample sizes at regularly spaced values of the dose metameter. An approximate test for similarity is proposed. If the tolerance distribution is known up to a scale parameter, then the transformation may be chosen so that the estimator is asymptotically fully efficient. An application to the thermal disinfestation of wheat is given.

Biometry↗
PubMed1980

A comparative trial of intra-nasal beclomethasone dipropionate and sodium cromoglycate in patients with chronic perennial rhinitis.

A double-blind crossover study has compared intra-nasal sodium cromoglycate (SCG) with beclomethasone dipropionate (BDP), and both drugs with placebo, in fifty-two chronic perennial rhinitis patients. BDP was significantly more effective in relieving symptoms than SCG (76.9% and 50% of the patients improved respectively, P < 0.01). Both drugs were more active than placebos but while BDP was very clearly more effective (P < 0.0005) SCG was only marginally better than its placebo (P < 0.05, Fisher; P = 0.068, chi 2). BDP was selected by 56% of the patients as the best agent for continuing therapy at the end of the trial. By contrast SCG was preferred by the same number of patients as chose the two placebos (11.5%).

Administration, Intranasal↗
PubMed1978

Scrotal and testical changes in canine brucellosis: a case report.

An Irish Setter with scrotal enlargement had an agglutination titer to Brucella canis of greater than or equal to 1:200, but B canis was not cultured from the blood. Unusual findings included draining ulcers in the scrotum from which B canis was cultured, a necrotic testicle, and inflammation of the entire scotum. Other clinical and postmortem findings were as previously described in other cases of naturally occurring and experimentally induced canine brucellosis.

Animals↗
PubMed1978

Idiopathic arterial calcification in infancy.

Three fatal cases of idiopathic arterial calcification in infancy are reported. The infants' ages ranged from 9 days to 3 months. Death was due to cardiac failure; in two cases caused by myocardial ischaemia, and in one by pulmonary hypertension. The histological findings are described and aetiology of the condition is discussed.

Arterial Occlusive Diseases↗
PubMed1977

Noncirrhotic portal hypertension in Felty's syndrome.

A case of Felty's syndrome with nodular regenerative hyperplasia of the liver, presinusoidal portal hypertension, and bleeding esophageal varices is reported. Increased splenic blood flow may be a contributing factor to the development of the regenerative nodules. The portal hypertension is postulated to be a result of intrahepatic vascular compression.

Esophageal and Gastric Varices↗
PubMed1977

Effects of chronic nicotine administration on RBC velocity in mesenteric capillaries of the rat.

The purpose of this study was to determine the effects of chronic administration of nicotine on red blood cell (RBC) velocity in single capillaries of the mesentery. Ten male rats consumed an average of 2.38 mg nicotine/kg/day, an approximate '2 pack' equivalent, in their drinking water for a period of 15-20 weeks. At the end of this time RBC velocity was measured in single capillaries of the mesentery. The data were compared to RBC velocities measured in a group of matched control rats. Red cell velocities in the control and nicotine groups averaged 1.22+/-0.23 and 0.59+/-0.10 mm/sec SEM, respectively. These values were significantly different (p less than or equal to 0.01). It is concluded that chronic administration of nicotine to rats in levels equivalent to tobacco smoking reduces resting capillary blood flow in the mesenteric circulation as indicated by differences in erythrocyte velocity.

Animals↗
PubMed1976

Alteration of mitochondrial function and lipid composition in Morris 7777 hepatoma.

Mitonchondria isolated from the Morris hepatoma 7777 demonstrated a markedly different phospholipid composition from those of control mitochondria, both with respect to the amounts of the various types present and the fatty acid composition. The level of polyunsaturated fatty acids in the mitochondrial phospholipids was lowered, wheras there was an increase in the level of monounsaturated fatty acids. Moreover, the usual distribution of saturated fatty acids at position 1 and polyunsaturated fatty acids at position 2 does not exist in hepatoma phospholipids; a high percentage of monounsaturated fatty acids was found at both positions. The cardiolipin content was lower in hepatoma mitochondria (3.7%) than in livers of animals with hepatomas (5.2%). There was, however, some compensation in the amount of acidic phospholipids in these mitochondria due to an increase in phosphatidylserine (4.9% versus 1.3%). The force-area curves of the hepatoma phospholipids spread on a monomolecular film demonstrated a smaller area per molecule than those from liver mitochondria. The zeta potential of liposomes of the hepatoma phospholipids (-45) was less than those of control mitochondria (-81), as determined by microelectrophoresis. The calcium-stimulated phospholipase A activity of the hepatoma mitochondria appeared to be more readily expressed than the same activity in liver organelles. The maximal activity was lower, however, than that noted in liver mitochondria. Furthermore, by following the incorporation of [3H]ethanolamine into mitochondria phospholipids, it was established that the conversion of glycerophosphorylethanolamine to glycerophosphorylcholine was increased in the hepatoma. These observations suggest dramatic changes in phospholipid metabolism in the hepatoma, at the level of both the endoplasmic reticulum and the mitochondrion. Accompanying the changes in phospholipid compositon and metabolism were alterations in mitochondrial energy-linked processes. The hepatoma mitochondria demonstrated lower respiratory control ratios even when isolated in an isotonic solution containing 1mM ethylenediaminetetraacetate and bovine serum albumin (0.5 mg/ml). This was due to increased state 4 respiration.

Animals↗
PubMed1975

Early effects of tobacco smoke exposure on vascular dynamics in the microcirculation.

The purpose of these studies is to examine the early effects of chronic tobacco smoke exposure on vascular dynamics in the mesenteric microcirculation. Female rats were exposed daily to tobacco smoke from five reference cigarettes for a period of 2 mo. At the end of this period the smoke-treated rats had gained 12 g less than sham-treated controls, and arterial blood pressure in the smoke-treated animals was slightly less than pressure in the sham-treated animals. These are characteristic effects of tobacco smoke exposure on rats. Following the treatment period, red blood cell (RBC) velocity in single mesenteric capillaries and microvascular pressures in arterioles and venules were measured in accordance to established methods. There was no significant difference in pressure distribution on the arterial side of the mesenteric vascular network, but pressure in the venules of the smoke-treated animals was significantly higher than that of the sham-treated group. In association with the higher venular pressure in the smoke-treated animals, capillary RBC velocity (an index of capillary flow) was significantly lower. The reduction in velocity was in proportion to the decrease in pressure drop (arteriole-venule) across the capillary network.

Animals↗