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Biomedical subjects

R Brandt

Publications and source records attributed to R Brandt.

At least 163 records · Page 9Linked to original sources
PubMed1978

The registration of slow ERG potentials of the perfused extracorporeal bull's eye.

Enucleated bull's eyes were perfused with blood and ERG recorded, with special attention paid to the slow components. When the blood flow was interrupted, the ERG components vanished in the following order: b wave, c wave, off-effect (d wave), and a wave. When the perfusion was continued afterward, we saw a variation in the standing potential that hinted at the biochemical activities causing slow electrical potentials of the retina.

Animals↗
PubMed1978

Intracellular pH and bicarbonate concentration in human muscle during recovery from exercise.

Eight subjects exercised on an ergometer until exhaustion. Femoral venous blood was analyzed for lactate, pyruvate, protein, electrolytes, and acid-base parameters. Muscle samples taken during the recovery period from m. quadriceps femoris were analyzed for water, electrolytes, lactate, and acid-labile CO2. Water content in the muscle biopsy sample was increased after exercise to 78.7 +/- 0.5% compared with the normal 76.7 +/- 0.8% at rest. The distribution of water between the extra- and intracellular space was calculated by the chloride method. In spite of elevated PCO2 in femoral venous blood the content of acid-labile CO2 was decreased in muscle after exercise. One minute after termination of exercise muscle CO2 was about half of the normal content at rest. During the recovery period muscle CO2 increased but was 20 min after termination of exercise still significantly below the value at rest. Intracellular pH (pHi) and bicarbonate concentration ([HCO3-]i) in muscle have been calculated. The validity of the assumptions underlying the calculations are thoroughly discussed. pHi decreased from the normal value at rest, 7.00 +/- 0.06 (mean +/- SD), to about 6.4 after exercise. [HCO3-] decreased from 10.2 +/- 1.2 mmol/l at rest to about 3 mmol/l after exercise. The changes are the greatest so far reported for an in vivo situation. After 20 min recovery pHi was almost the same as at rest, whereas bicarbonate was still well below.

Acid-Base Equilibrium↗
PubMed1977

Urinary glucose and vitamin C.

The recent popularization of self-prescribed large doses of vitamin C has increased the possibility for erroneous conclusions to be drawn from standard clinical methods used in urinary glucose monitoring, due to interference with these methods by the greatly elevated excretion of vitamin C. The coupled-enzyme-chromogen strip tests showed erroneously negative glucose levels in urines of both a diabetic individual and a subject with a genetic low renal threshold for glucose when they were supplementing their normal diets with 1-2 g vitamin C per day. With this regimen, their urinary vitamin C levels reached 200 mg/dl (11.4 mmol/l). For normal urine with vitamin C added, false-positive tests for glucose were found using Benedict's reagent when vitamin C was present at 250 mg/dl (14.3 mmol/l) or higher concentrations. In diabetic individuals consuming large quantities of vitamin C, this interference with standard coupled-enzyme-chromogen strip tests or Benedict's test could present a significant problem in diagnosis and clinical management of the disease. A simple anion exchange method of treating the urine was used to correct the false results.

Adult↗
PubMed1976

Passage of diazepam and desmethyldiazepam into breast milk.

The aim of this investigation was to study whether and to what extent 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one (diazepam, Valium) passes into the breast milk during repeated oral administration to nursing mothers. It was shown that diazepam and its main and also active metabolite desmethyldiazepam passed into the milk. Their concentrations, however, remained small as compared to plasma values. Desmethyldiazepam levels in the milk were consistently higher than those of diazepam. These results are explained by the relative binding of both substances to plasma proteins. The maximum quantities of diazepam + desmethyldiazepam that can possibly be absorbed by a newborn with the milk of a mother receiving 10 mg Valium daily, are considered to be too small to cause any untoward effects in the baby. If, however, high doses of Valium must be administered repeatedly, breast-feeding should be discontinued for safety reasons.

Adult↗
PubMed1975

RAST-based allergen assay methods.

The RAST principle has been utilized for the detection and assay of allergens of various origins. RAST-based methods have the advantage of being convenient, accurate and specific by making use of the IgE antibodies, considered as mediators of the atopic allergic reactions, as reagents in vitro. Two improved assay procedures, a direct titration and an inhibition method, have been used for the estimation of extract potencies and for the assay of separate allergens. The specificity of the assays is determined by the specificity of the IgE (sera from allergic patients) used as the main reagent. Specific assay of separate components in heterogeneous extracts may be achieved in some cases by careful characterization of the sera or by selective blocking of irrelevant IgE. The potency of allergen concentration may be calculated and expressed in arbitrary units, and the accuracy and sensitivity of the two methods are similar. The coefficient of variation is in the range 10 to 25% provided that standardized reagents are used. Sensitivity of the assays is about 200 ng per ml. The lower limit for detection of allergen is 10-100 times lower.

Allergens↗