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Biomedical subjects

J D Brown

Publications and source records attributed to J D Brown.

At least 127 records · Page 7Linked to original sources
PubMed1979

High resolution microchemical analysis using soft X-ray lithographic techniques.

High resolution x-ray lithographic studies of cells from chick embryo hearts dried by the CO2 critical point method have been made with soft x-ray radiation of different wavelengths. A marked difference in the relief replica in polymethyl methacrylate (PMMA) resulting from the differential absorption by the dried cells of carbon K alpha radiation at 4.48 nm and broad band synchrotron radiation (SR) with lambda is greater than 1.5 nm demonstrates the potential usefulness of the technique in making high resolution (approximately or equal to 10 nm) chemical identification of the constitutents which make up the various parts of the cell.

Animals↗
PubMed1978

Pituitary pigmentary hormones. Relationship of melanocyte-stimulating hormone to lipotropic hormone.

Pituitary control of pigmentation has known for more than 60 years. Since 1969, beta-melanocyte-stimulating hormone (beta-MSH) has been accepted as the main pituitary pigmentary hormone in man. Its "constant companionship" with adrenocorticotrophic hormone (ACTH) has also been repeatedly demonstrated. Current investigations challenge both of these concepts. Human beta-MSH immunoreactivity has been shown to be actually due to beta-lipotropic hormone (beta-LPH), a larger molecule that within itself contains the entire amino acid sequence of beta-MSH. Human beta-MSH does not exist in vivo; it is merely an extraction artifact formed by enzymatic degradation of beta-LPH. It would appear likely that beta-LPH, not beta-MSH, is the constant companion of ACTH.

Adrenocorticotropic Hormone↗
PubMed1978

Pathological observations on experimental cytomegalovirus infections in pregnancy.

Cytomegalovirus injected intramuscularly or intraperitoneally into mice on the 8th day of pregnancy resulted in a significant retardation in foetal growth and a reduced number of offspring surviving until near-term. Pathological changes consisted of inflammatory cell infiltration in the liver, heart, salivary glands and adrenal cortex of affected animals. Necrotic changes were also present in the adrenal cortex in most severely affected animals following intraperitoneal injection of virus. Intraperitoneal infection led to a frank peritonitis and marked splenic necrosis with a degeneration and inflammation of visceral fatty tissue and lymphadenitis. In contrast, intramuscular injection of virus did not produce a peritonitis but the spleen was greatly enlarged with reaction centres and increased numbers of lymphocytes being identified at histology. As a consequence of cytomegalovirus infection in pregnant mice foetal growth impairment and intrauterine death was seen. This was related to the severity of pathological changes in the mothers. In those animals dying or appearing sick at near-term, most foetuses were dead and resorbing. Since murine cytomegalovirus was not identified by inclusion body formation in foetal or placental tissues in this study and virus has not been isolated from these tissues previously, it was concluded that the mechanism for the impaired foetal growth was of an indirect nature and attributable primarily to a severe generalised maternal illness.

Animals↗
PubMed1978

Increased dependence on visual information for movement control in patients with Parkinson's disease.

Studies were made of visually and non-visually guided movements by patients with Parkinson's disease. The subjects moved a light, horizontal handle using rotation primarily about the elbow. During visually guided trials both handle and target positions were displayed to the subject; during non-visually guided trials only the handle position was displayed. During non-visually guided trials all patients showed a tendency for an overall flexion drift, although there was no change in average movement amplitude. The overall error in position by the end of the non-visually guided trials was greatly in excess of the reported values for passive displacement thresholds in normal subjects. It is suggested that the data indicate an increased dependence on visual information for control of motor activity in Parkinson's patients.

Aged↗
PubMed1978

Clinical experience in the use of cefuroxime in gonorrhoea.

Cefuroxime, a new antibiotic derived from cephalosporin-C which is very stable in the presence of beta-lactamases produced by Gram-negative organisms, was used to treat 856 male patients and 340 female patients with uncomplicated gonorrhoea. In men the drug was used in three different doses, 1.5 g, 1 g, and 750 mg plus 1 g probenecid; in women 1 g and 750 mg cefuroxime plus 1 g probenecid was used. Cure rates ranged from 94.8% to 99.3%. The antibiotic was well tolerated and was free from side effects. Cefuroxime would be a valuable and efficient substitute for penicillin in the treatment of gonorrhoea due to beta-lactamase-producing strains of gonococci.

Cephalosporins↗
PubMed1978

Measurement of local cerebral blood flow with iodo [14C] antipyrine.

The autoradiographic diffusible tracer technique for the measurement of local cerebral blood flow was originally designed for use with the radioactive, inert gas 131I-labeled trifluoroiodomethane and is applicable only with tracers that exhibit unrestricted diffusion through the blood-brain barrier. Because of the technical problems associated with the use of gaseous tracers, a suitable nonvolatile tracer has been sought. [14C] Antipyrine has been used previously and found to be unsuitable because of limitations in its diffusion through the blood-brain barrier. An analogue of [14C]antipyrine, iodo [14C]antipyrine, exhibits higher partition coefficients than [14C]antipyrine between nonpolar solvents and water and might, therefore, be expected to diffuse more freely through the barrier. Its use as the tracer in the local blood flow technique leads to values considerably above those obtained with [14C]antipyrine in the rat and cat and essentially the same as those obtained with the gas trifluoro[131I]iodomethane in the cat. Iodo[14C]antipyrine appears, therefore, to be a satisfactory nonvolatile tracer for the measurement of local cerebral blood flow.

Animals↗
PubMed1978

Cerebral oxidative metabolism during intrauterine growth retardation.

Cerebral oxidative metabolism during intrauterine growth retardation was investigated utilizing a pregnant-rat model. Dams were subjected to unilateral uterine artery ligation on the 17th day of gestation. At term, they were sacrificed by decapitation and the fetuses delivered by cesarean section. Body and brain weights of fetuses from ligated uterine segments were smaller than those of offspring from nonligated horns of the experimental rats or those from sham-operated dams. Blood glucose at birth was reduced by 25% in growth-retarded fetuses. Cerebral oxidative metabolites, including glycogen, glucose, lactate, ATP, and phosphocreatine, were not different from control levels. These findings suggest that neither tissue hypoxia nor deficient glucose delivery to brain can account for the stunted cerebral growth observed in fetuses following uterine artery ligation.

Adenosine Triphosphate↗
PubMed1977

Periodic lateralized epileptiform discharges (PLED's) and nystagmus retractorius.

A 57-year-old diabetic woman presented with focal right-sided seizures and hyperglycemia. She later showed periodic lateralized epileptiform discharges (PLEDs), originating in the left hemisphere, which were temporally associated with nystagmus retractorius. It appears that the left hemisphere epileptiform activity diffusely excited brainstem structures via polysynaptic pathways to produce the nystagmus.

Diabetic Neuropathies↗
PubMed1977

The effect of tolbutamide on contractility and cyclic adenosine 3':5'-monophosphate concentration in the intact beating rat heart.

The effect of tolbutamide on contractility and the concentration of cyclic adenosine 3':5'-monophosphate (cyclic AMP) in ventricular muscle was examined in the intact beating rat heart. The hearts were perfused in a nonrecirculated (Langendorff) fashion. Bolus injections of tolbutamide caused an increase in cardiac contractility. This increase in contractility was markedly inhibited when bovine albumin (3 g/100 ml) was present in the perfusing fluid. The increase in contractility caused by tolbutamide was not preceded by or associated with any change in the concentration of cyclic AMP in the ventricular muscle. Further studies utilizing a simultaneous injection of norepinephrine and tolbutamide demonstrated no significant effect of this combination on the concentration of cardiac cylcic AMP produced by an injection of norepinephrine alone. Our findings suggest that in the intact beating rat heart the positive inotropic effect of tolbutamide is not mediated via an increase in the concentration of cardiac cyclic AMP and that tolbutamide does not significantly potentiate the effect of catecholamines on cardiac cyclic AMP concentration.

Albumins↗