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Biomedical subjects

J G Brown

Publications and source records attributed to J G Brown.

At least 37 records · Page 2Linked to original sources
PubMed1987

Characterization of neuraminidases produced by various serotypes of group B streptococci.

Neuraminidase produced by 11 strains of group B streptococci (GBS), from serotypes Ia, Ib, Ic, II, and III, were characterized according to molecular weight, antigenic identity, and substrate specificity. Following growth in a chemically defined medium, ammonium sulfate-concentrated culture supernatants were assayed for activity with bovine submaxillary mucin as substrate. Neuraminidase produced by GBS strain 122 (serotype III) was purified by a combination of salt fractionation, affinity chromatography with Affi-Gel Blue, ion-exchange chromatography with DEAE-cellulose, and gel filtration on Sephadex G-200. Purified neuraminidase was used to immunize rabbits, and the resultant antiserum reduced the activity of purified neuraminidase from strain 122 by 87.7%. The antiserum also reduced the activity of neuraminidases produced by the other four serotypes by between 78.3 and 90%. Molecular weight estimates of the neuraminidases produced by the various serotypes were obtained by gel filtration chromatography on Sephadex G-200. The molecular weights obtained for the neuraminidases from the representative strains of each serotype ranged from 110,000 to 180,000. In addition, all of the GBS neuraminidases examined (regardless of the producing serotype) were active only on bovine submaxillary mucin. On the basis of these results, it appears that the neuraminidases produced by different GBS serotypes are quite similar.

Antibodies, Bacterial↗
PubMed1987

Impedance plethysmography. A screening procedure to detect deep-vein thrombosis.

Impedance plethysmography has great potential in the non-invasive detection of dangerous iliofemoral thrombosis. It was used to examine 198 patients undergoing total hip replacement for evidence of proximal venous segment thrombosis. There were 13 abnormal results, and subsequent venography in 12 of these revealed a false-positive rate of 4.0%; there was one false-negative result giving a sensitivity of 85.7%. A venographic study of 46 other patients clinically suspected of having a proximal deep-vein thrombosis confirmed this sensitivity. The iliofemoral thrombosis rate was 3.9% after total hip replacement and this rate increased significantly in the group of patients over 70 kg in weight. Impedance plethysmography was found to be a useful non-invasive screening procedure for potentially fatal proximal venous thrombosis.

Adult↗
PubMed1987

Spinal anaesthesia for surgical correction of fracture of the proximal femur.

One hundred and one patients underwent surgical correction of fractures of the proximal femur under spinal anaesthesia. There were 14 deaths in the first three months following surgery. Advancing age, poor pre-anaesthetic status, reduced pre-operative mobility and deteriorating mental function were reliable prognostic indicators of fatal outcome. Spinal anaesthesia for this type of surgery may well be the technique of choice because it avoids the use of drugs which depress the respiratory, cardiac and central nervous system. It also reduces the need for potent post-operative analgesics with similar depressant effects, and may afford some protection against thromboembolic complications. The very low early mortality in this series testifies to the safety of the anaesthetic technique.

Aged↗
PubMed1986

Nursing management of the patient with total en bloc resection of the temporal bone.

En bloc resection of the temporal bone is an extensive and complicated surgical procedure for removal of malignancies of the ear and temporal bone. The lengthy surgical procedure (18 to 36 hours) and the resultant functional disabilities and cosmetic deformities create special nursing management concerns. Preoperative preparation, carotid artery occlusion, and postoperative nursing management are discussed. Communication and psychological issues for the patient and family are presented.

Combined Modality Therapy↗
PubMed1985

Raised intraocular pressure: an alternative method of referral.

To assess delay in referring patients with suspected glaucoma two methods were studied in a randomised trial: direct referral from optician to ophthalmologist and referral through the patient's general practitioner. Direct referral was reliable for all 49 patients involved, whereas, of the 44 patients referred through their general practitioner, seven waited over three weeks for referral.

Family Practice↗
PubMed1983

The effect of tri-iodothyronine administration on protein synthesis in the diabetic rat.

In young male rats diabetes caused decreases in circulating free tri-iodothyronine and RNA concentration in liver and muscle, and in the rate of protein synthesis per unit of RNA (RNA activity) in muscle. Tri-iodothyronine treatment significantly increased RNA concentrations, but not RNA activity, in these tissues. Thus: (1) impaired thyroid status is a component of the diabetic condition; (2) tri-iodothyronine cannot stimulate the translational phase of protein synthesis in the diabetic rat.

Animals↗
PubMed1983

Dose response of protein turnover in rat skeletal muscle to triiodothyronine treatment.

Skeletal muscle protein turnover has been examined in thyroidectomized rats treated with 0, 0.3, 0.75, 2, 20 and 100 micrograms triidothyronine/day for 7 days by implanted osmotic minipump. Protein synthesis in gastrocnemius, plantaris and soleus muscle were measured in vivo by the constant infusion method and protein degradation estimated as the difference between gross and net rates of synthesis. Serum levels of triidothyronine (T3) and insulin were also measured in addition to oxygen consumption rates in some cases. Compared with untreated intact rats muscle growth rates were unchanged at 0.3, 0.75 and 2 micrograms T3/day and, judging by plasma T3 levels, 0.75 microgram T3/day was a replacement dose. Slowing of growth was evident in the untreated thyroidectomized rats mid-way through the 7 day experimental period (6-7 days after throidectomy). High doses of T3 (20 and 100 micrograms/day) promptly supressed growth but there was subsequent recovery. Protein synthesis and degradation were generally lower in the hypothyroid state and normal or elevated in the hyperthyroid state. The changes in protein synthesis were mediated by changes in both RNA concentration and RNA activity (protein synthesis per unit RNA). Gastrocnemius and plantaris muscles were most responsive in the hypothyroid range. Since protein synthesis is particularly depressed in these muscles in malnutrition, the fall in protein degradation induced by the lowered thyroid status in this condition will be an important adaptive response to conserve protein. The increased protein turnover in the hyperthyroid rats was most marked in the soleus muscle and it is argued that this is necessary to allow the changes in protein composition and metabolic character which occur in response to hyperthyroidism in this muscle.

Animals↗
PubMed1981

Thyroid hormones and muscle protein turnover. The effect of thyroid-hormone deficiency and replacement in thryoidectomized and hypophysectomized rats.

We have investigated the effects of thyroidectomy, hypophysectomy and 3,3',5-tri-iodothyronine replacement on protein synthesis and degradation in skeletal muscle in vivo. Thyroidectomy resulted in a decrease in the rate of protein synthesis as a result of a loss of RNA. However, RNA activity, the rate of protein synthesis per unit of RNA, was not decreased. This was the case in both young growing rats and mature nongrowing rats. Tri-iodothyronine treatment of thyroidectomized rats increased protein synthesis by increasing RNA concentration without changes in RNA activity, and this occurred even when food intake was restricted to prevent any increase in growth. The rate of protein degradation was decreased by thyroidectomy and increased by tri-iodo-thyronine replacement in both animals fed ad libitum and food-restricted animals. Hypophysectomy decreased protein synthesis by decreasing both RNA concentration and activity. these changes were reversed by tri-iodothyronine treatment even in the presence of persistent marked hypoinsulinaemia. This indicates that tri-iodothyronine can activate athe translational phase of protein synthesis in muscle in the absence of significant quantities of insulin. However, tri-iodothyronine does not seem to be obligatory for the maintenance of normal RNA activity in muscle, since in the thyroidectomized rat, in which plasma insulin concentrations are normal, RNA activity is maintained. From a consideration of the magnitude of changes in RNA activity observed in these experiments, it would appear that alterations in rates of elongation as well as initiation are involved in the changes in RNA activity.

Animals↗
PubMed1980

Quantitative importance of non-skeletal-muscle sources of N tau-methylhistidine in urine.

Direct measurement of N tau-methylhistidine turnover in skeletal muscle, skin and gastrointestinal muscle indicates that these three tissues contribute only 24.9, 6.8 and 9.8% of the total urinary excretion. Measurement of the decay rate of radioactively labelled N tau-methylhistidine in urine indicates that skeletal muscle accounts for 74.5% of the urinary excretion and this is probably an overestimate. These results suggest that the common assumption, that N tau-methylhistidine in urine originates almost entirely from skeletal muscle, may be wrong.

Animals↗
PubMed1979

Protein degradation and the regulation of protein balance in muscle.

The rate of of protein degradation in muscle changes in many states but the nature of these changes is often paradoxical. Thus there can be increases during growth (anabolic increases) as well as during wasting (catabolic increases). Decreases can occur during growth (anabolic decreases) as well as during wasting (catabolic decreases). These changes are observed in man (as judged by changes in 3-methylhistidine excretion) and in experimental animals. The nature of the changes is not understood but it is possible that muscle growth induces increased degradation as part of the accompanying myofibre remodelling. The rate of protein degradation can also be influenced by thyroid status, since in thyroid deficiency degradation is reduced and can be stimulated by triiodothyronine. This response is independent of changes in muscle growth. Finally, acute exercise suppresses protein degradation in vivo in man as well as suppressing protein synthesis (in vivo in rats). When protein degradation rates change, acid proteinase activities also change in muscle. The anabolic increase in degradation appears to involve increases in mainly cathepsin D whereas catabolic increases in degradation are associated with an increase mainly in pepstatin-insensitive acid autolytic activity.

Adult↗
PubMed1976

Effect of water temperature during cold exposure on thermogenic drinking in rats.

Availability of water at temperatures higher than ambient (15, 25, 35 degrees C) failed both to affect the ratio of water to food intake during exposure to cold air (5 degrees C) and to influence the thermogenic (postcold exposure) drinking response of rats which characteristically occurs immediately after removal from cold air. Thus, availability of warm water during exposure to cold appeared to have no influence on cold-induced dehydration in rats. A specially constructed drinking apparatus was used in this study. It was designed to maintain water at temperatures greater than ambient during exposure to cold. Details for construction of the apparatus are provided.

Animals↗
PubMed1975

A double blind trial of lithium carbonate and haloperidol in Huntington's chorea.

Six patients with a family history of Huntington's chorea (HC) participated in a double blind crossover trial involving four treatments--lithium carbonate, haloperidol, lithium carbonate and haloperidol, and placebo. Each treatment was administered for three weeks and, at the end of each treatment period, assessments were made of chorea and a number of psychological variables. None of the treatments significantly affected chorea measurements. With regard to the psychological variables, the levels of irritability, the frequency of angry outbursts and depression did appear to be affected in some patients by the treatment. Three patients improved on a combination of lithium carbonate and haloperidol while the remaining three did not. Haloperidol alone significantly raised depression ratings above levels for other treatments including placebo. It is suggested that lithium carbonate and haloperidol together should be seriously considered in the treatment of HC when patients are excessively irritable and impulsive.

Anger↗
PubMed1974

Translation of Pseudomonas aeruginosa bacteriophage PP7 RNA by a cell-free amino acid incorporating system from Escherichia coli.

We have compared the activities of the RNA genomes of Pseudomonas aeruginosa phage PP7 and coliphages Qbeta and f2 in a cell-free amino acid incorporating system derived from Escherichia coli. The rate of incorporation of [(14)C]leucine in the PP7 RNA-directed system is greater than in the systems directed by either Qbeta or f2 RNA. The response to changes in phage RNA concentrations is similar in all the systems, reaching a saturation level at 0.75 to 1.0 mg of RNA per ml of reaction mixture. Analysis of complete reaction mixtures of the PP7 RNA and of the Qbeta RNA systems by sucrose gradient centrifugation shows generally similar patterns for both RNAs. The principal differences are that in the PP7 system a slightly higher percentage of RNA forms ribosome complexes and that the polysomes are somewhat smaller. PP7 RNA is also degraded more extensively during the reaction than is Qbeta RNA. Analysis of the products of the reactions by acrylamide gel electrophoresis shows that PP7 coat protein is the only identifiable product of the PP7 RNA-directed system, suggesting that only the coat protein cistron is translated by E. coli ribosomes.

Amino Acids↗