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Biomedical subjects

B Paletta

Publications and source records attributed to B Paletta.

At least 19 recordsLinked to original sources
PubMed1993

Determination of renal clearance of neopterin by a pharmacokinetic approach.

Pharmacokinetic modelling was used to determine the glomerular filtration rate and tubular secretion of neopterin, a marker for cellular immune activation. The method involves parameter identification employing the transient venous plasma concentration profiles of marker substances. By combined i.v. injection of neopterin and inulin which is excreted exclusively via glomerular filtration, neopterin was shown to be excreted in addition to glomerular filtration, by tubular secretion: clearance of inulin, 112 (S.D. 2.2) ml/liter; clearance of neopterin, 499 (S.D. 79.7) ml/min. A pilot experiment using in addition p-amino hippuric acid suggests that neopterin and p-amino hippuric acid may employ the same carrier system for tubular secretion.

Adult↗
PubMed1991

Free epinephrine in the ischemic blood of muscle transplants in the rabbit.

A stimulated autotransplantation of the rectus femoris muscle in the rabbit was performed by clamping of the blood vessels for 2 h and cutting and suturing of the nerve. Four months after this operation, isometric contractions of the reinnervated muscle were recorded. Comparing controls and postoperation cases, the recovered strength measured about 65%. Due to operation stress, the epinephrine content in plasma was about 420 pg/ml; in plasma of the ischemic muscle it was enhanced to more than 600 pg/ml. During or immediately after ischemia, conjugated epinephrine is assumed to be converted to the free hormone. In systemic blood additionally about 200 pg/ml epinephrine were identified as glucuronides. The activity of adenylate cyclase increased, while the acetylcholine esterase decreased to one-half after nerve cutting.

Acetylcholinesterase↗
PubMed1990

Quantitative determination of some pharmaceuticals in bulk drugs and tablets by proton magnetic resonance (PMR) spectroscopy.

The quantitation of allopurinol, I, flucytosine, II, meclophenoxate hydrochloride, III, and phenylephrine hydrochloride, IV, in bulk drugs and tablets was achieved by simply developed, rapid and specific methods using the proton magnetic resonance (PMR) spectroscopy. Trifluoroacetic acid and dimethylmalonic acid were the solvent and the internal standard respectively.

Chemical Phenomena↗
PubMed1989

The coenzyme nicotinamide adenine dinucleotide (NADH) improves the disability of parkinsonian patients.

The coenzyme nicotinamide adenine dinucleotide (NADH) has been used in an open label trial as novel medication in 34 patients with Parkinson's disease, using an intravenous administration technique. In all patients a beneficial clinical effect was observed. 21 patients (61.7%) showed a very good (better than 30%) improvement of disability, 13 patients (38.3%) a moderate (up to 30%) improvement. Concomitant with the improvement of the disability the urine level of homovanillic acid (HVA) increased significantly in all patients (in some patients by more than a 100%). The daily "on phases" of the patients could be increased from 2 up to 9 hours in the individual patients by NADH administration.

Aged↗
PubMed1989

The influence of noise stress on plasma epinephrine and its binding to plasma protein in the rat.

The influence of a hypersonic noise stress on plasma epinephrine level and on the distribution of i.v. administered radioactive epinephrine between the free and the protein bound form was studied in the rat. The noise stress caused an elevation of epinephrine by 180%. The radioactive hormone was removed more slowly from the vascular compartment of the stressed animals, concomitantly the protein bound fraction increased.

Animals↗
PubMed1988

Quantitative characterization of diet effects on glucose tolerance in rabbits.

Normal, atherogenic and butter-enriched diets were given to three groups of rabbits during six months. The effects of the three forms of diet after six months were examined with the intravenous glucose tolerance test, which was evaluated by computer-aided model-fitting and parameter identification. Long-term effects are reflected in parameters such as pancreas sensitivity and the glucose utilization rate constant as a measure of peripheral insulin sensitivity. In these terms, the atherogenic diet caused a diminution of both pancreatic and peripheral sensitivity, whereas the butter-enriched diet led to an increase in glucose utilization and a decrease in pancreatic sensitivity relative to the system parameters of the normally fed control animals. Related to the findings about metabolic regulation are indications for an endocrinological approach to the problems of cholesterogenesis and atheroma formation.

Animals↗
PubMed1981

System identification of the control of gluconeogenesis in the intact organism under conditions of long-term stress.

In this article a system-theoretic approach to hormonal control of gluconeogenesis as observed in the intact organism under hypoglycemia and hypoxia is attempted. Under such conditions the secretion of the stress hormone corticosterone by the adrenal cortex is effected by neural control centres inducing the synthesis of gluconeogenetic enzymes which catalyze the production of glucose from amino acids originating from body tissues. The time courses of the hormonal, enzymatic and metabolic quantities measured are evaluated in the framework of a model in the form of a system of differential equations, the parameters of which are determined by a numerical search procedure.

Animals↗
PubMed1981

Plasma concentrations of glucose, corticosterone, glucagon and insulin and liver content of metabolic substrates and enzymes during starvation and additional hypoxia in the rat.

The plasma levels of corticosterone, insulin and glucagon, and the concomitant changes in the levels of several liver enzymes and metabolites were measured in intact rats in the basal state during 24 hours and under conditions of food deprivation and hypoxia. The levels of the following enzymes and metabolites were examined: phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, pyruvate kinase, phosphofructokinase, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, glucose, glucose-6-phosphate, glycogen, fructose-6-phosphate, hexokinase, tyrosine amino-transferase and tryptophan oxygenase. During food deprivation, the increased gluconeogenesis is possibly a result of glucagon activity. In contrast, however, during hypoxia the increase in gluconeogenesis seems to be a result of the higher plasma level of corticosterone. During starvation, the insulin concentration dropped steadily and came close to zero.

Animals↗
PubMed1980

The influence of an atherogenic, semisynthetic diet on cholesterol metabolism in rabbits.

The influence of a cholesterol-free, semisynthetic diet on the cholesterol content and on the incorporation of radioacetate into cholesterol in liver, aorta and intestinal mucosa of the rabbit was tested over periods of 3 and 6 months. The incorporation of radioacetate in the liver reached a maximum after 3 months. In contrast to this, the rate of acetate incorporation in the aorta and mucosa continued to rise throughout the entire test period. The cholesterol level in serum ran parallel to the hepatic cholesterol synthesis reaching a maximum after 3 months. While the cholesterol content of the liver remained unchanged, it rose in the aorta and mucosa. These results favour the assumption that hypercholesterolemia was not due to a defect in removal of cholesterol from the plasma compartment, but to an increased biosynthesis.

Animal Feed↗
PubMed1980

Studies of enzyme reactions in open systems.

An experimental arrangement is described which allows studies of the temporal performance of enzyme reactions (also reactions of complexes of enzyme chains) under conditions of open systems. The various steady-state properties of such open systems can be recognized by measuring their input and output [1,2]. The various levels of flowing equilibria are perturbed by applying molecular modulators to the system, and the data obtained are compared to those found in closed systems. In order to prove the accuracy of the experimental configuration, the determination of Km in a one-substrate reaction is carried out in the open system, using only one concentration of substrate at various flow rates.

Enzymes↗
PubMed1980

The influence of a cholesterol-free semisynthetic diet on the lipid metabolism in rabbits.

The influence of a cholesterol-free, semi synthetic diet on the total lipid synthesis and on the lipid content of serum, liver, aorta and intestinal mucosa of the rabbit was tested for the duration of three months, and, respectively, six months. Also, the changes in these parameters after a 38-hour period of fasting was examined. The total lipid synthesis in the liver and aorta ran parallel to the lipid level in serum with a peak in radioacetate incorporation into total lipids occuring after three months. In contrast to this the rate of lipid synthesis in the mucosa continued to rise throughout the entire test period. While the lipid content of the mucosa remained unchanged by the diet, it rose in the liver and aorta. The effect of fasting in the three organs was greater after three months than after six months in respect to the incorporation of radioacetate. The serum lipids, too, sank further during fasting after three months than after six.

Animals↗
PubMed1976

Time function of corticosteroid levels in the blood plasma of rats under the influence of 222Rn inhalation.

The time function of cortocosteroid level in plasma of rats under two different 222Rn concentrations was investigated. Both curves show a maximum after 8h. Whereas the higher activity of 222Rn produces a second maximum after 5 days, the lower activity reaches its second maximum not before 9 days. From both time functions, a two-step mechanism in the intracellular control can be concluded.

Adrenal Cortex Hormones↗
PubMed1976

[Human urinary fluoride excretion at various ages (author's transl)].

3 groups, each consisting of 5 subjects in the following age ranges (A 4 to 6 years, B 25 to 45 years, C 60 to 70 years) were given fluoride in the form of a single dose of 6 mg. Fluoride excretion in the urine was subsequently investigated over a period of 24 hours. In a second experiment a daily dose of 6 mg of F- was given to the 3 groups over a period of 10 days. The urinary excretion was determined in 24-hour urine samples. The results are presented in two figures. 1. A time drift in urinary fluoride excretion in the direction of delayed fluoride metabolism was seen in group C subjects. 2. A periodic increase in the urinary fluoride values was also seen in these elderly subjects, indicative of an altered regulatory mechanism.

Adolescent↗
PubMed1975

The effect of hunger on free fatty acid and corticosterone plasma levels in rats.

The time function of free fatty acids and of corticosterone in plasma in fed and fasted rats was investigated. Also a study of the influence of hypoxia on the concentration of plasma free fatty acids was carried out. Whereas fasting does not seem to stimulate lipolysis markedly before 12 h, 2 h of hypoxia elevate the free fatty acid level to its maximum. In the fasted condition, all values are significantly higher than corticosterone in the fed animal.

Animals↗