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Biomedical subjects

K Albert

Publications and source records attributed to K Albert.

72 records · Page 4Linked to original sources
PubMed1979

Effect of long-term alcohol intake on the cardiovascular system of the rat.

A group of rats was fed on control liquid diet, while another group was fed on liquid diet containing alcohol up to 36% of the total calories. After 4, 8 and 12 weeks of treatment ECG, haematocrit, histological structure of the heart, blood pressure, cardiac output, distribution of the organ fraction of cardiac output (by Sapirstein's method and 85Sr labelled microsphere technique), nutritive blood flow and circulatory resistance of the organs were studied. A mild repolarization disturbance was shown by the ECG record of the alcohol exposed animals. Haematocrit values and the histological structure of the heart did not change in any of the groups. Relative heart weight increased, blood pressure, total peripheral resistance and nutritive blood flow of the myocardium decreased, while myocardial vascular resistance increased. There was no significant interaction between the effects of alcohol and the duration of exposure to alcohol for any of the parameters monitored. It is concluded that chronic alcohol intake should be taken into consideration in aetiology of ischaemic heart disease.

Animals↗
PubMed1978

The contributions of differing degrees of acute and chronic malnutrition to the intellectual development of Jamaican boys.

The purpose of this paper is to determine whether differing degrees and types of malnutrition cause differing degrees of mental impairment. Subjects were 59 Jamaican boys hospitalized for malnutrition in infancy and whose intelligence was assessed at school age. The measure used for degree of chronic malnutrition was height for age and for acute malnutrition weight for height. The measure of intelligence was the I.Q. (WISC). Because the social environment in which a child lives influences his intellectual development, a measure of social background was used as an independent variable in addition to the nutrition measures. Social background showed a significant effect on I.Q. but neither measure of nutrition was significant. A further analysis using comparisons who had not been hospitalized for malnutrition suggests that malnutrition may contribute to mental impairment, through a threshold effect rather than acting as a continuous variable where increasing degrees of malnutrition cause increasing degrees of mental impairment.

Acute Disease↗
PubMed1976

Activity of erythropoietin and renin in renal venous blood of hypertensive patients.

Plasma activities of renin and erythropoietin were determined in the renal veins of the right and left kidneys of hypertensive patients. The patients were divided into the following groups either according to the origin of the hypertension (group 1: control for essential hypertension, group 2: renovascular hypertension) or according to the hormone levels (group 3: renin activity exceeding 10 ng/litre in at least one of the renal veins and group 4: erythropoietin activity higher than 4% 59Fe incorporation in at least one of the renal veins). In groups 1, 2 and 3 a statistically significant difference in renin activity was found between the kidney with the higher renin activity and that with the lower activity. However, in group 4, the side, which showed elevated erythropoietin values also had higher renin activity as compared to the essential hypertensive group. Erythropoietin activity probably does not parallel the increased renin activity found in renovascular hypertension or in some cases of non-renovascular hypertension. However, in several cases of renal vascular alterations, both systems can be activated simultaneously.

Erythropoietin↗
PubMed1975

Circulatory regulation in anuric rats: anuria and haemorrhagic hypotension.

In rats made anuric by ureteral ligation or by creating a bladder-caval venous shunt, cardiac index increased and total peripheral resistance decreased proportionally to the change in the serum NPN level. Circulating blood and plasma volume did not change. In ureteral-ligated or bladder-caval venous-shunted rats, cardiac output and its organ fractions were determined by SAPIRSTEIN'S technique. In the ureteral-ligated animals, vasoconstriction in the kidneys, and vasodilation in the skin were found. After bladder-caval shunt, vasodilatation developed in the myocardium, gut, skin and carcass. After ureteral ligation, posthaemorrhagic shifting decreased mainly the renal flow, while after a bladder-caval venous shunt, mainly the renal and intestinal flows.

Animals↗
PubMed1969

Synaptic vesicles in electron micrographs of freeze-etched nerve terminals.

Freeze-etched neuropil of the cat subfornical organ was examined with the electron microscope for synaptic vesicles. Round vesicles were found exclusively in both unfixed and aldehyde-fixed specimens. Range of diameters and histograms failed to differ significantly between freeze-etched and conventionally prepared material. The mnode of distribution of diameters was approximately 500 angstroms. Round stomata (approximately 350 angstromns in diameter) were found at the outer surface of the plasmalemma of nerve terminials; they are interpreted as pinocytotic vesicles.

Aldehydes↗
PubMedDate not supplied

In vivo 19F nuclear magnetic resonance of a monofluorinated neuroleptic in the rat.

In vivo 19F NMR measurements of the fluorinated neuroleptic melperone [4'-fluoro-4-(4-methylpiperidino)-butyrophenone hydrochloride] in the rat brain were performed using a geometrically optimized surface coil at 4.7 T. It was possible for the first time to detect a signal of a monofluorinated neuroleptic drug with a time resolution of 30 min after i.p. application. The kinetic time course of the investigated neuroleptic melperone was recorded over 6 h and showed that the half-life in the rat brain is 4.3 h. The total amount of drug and its metabolites in the brain was estimated to be 50 microM. the chemical shift of the 19F NMR signal shows the same upfield shift relative to that in aqueous solution as has been reported for trifluorinated neuroleptic drugs.

Animals↗
PubMedDate not supplied

In vivo metabolism of [4-13C]phenacetin in an isolated perfused rat liver measured by continuous flow 13C NMR spectroscopy.

Continuous flow 13C NMR spectroscopy has been used for the first time to monitor the metabolism of a 13C labeled drug in an isolated liver. Continuous and almost immediate information on the metabolite formation could be obtained using 13C labeled phenacetin without alteration of the biological system. The data are consistent with those observed by conventional techniques (HPLC, aliquot 13C NMR measurements). From the biological point of view the sensitivity of continuous flow 13C NMR spectroscopy is still low (10(-3) M). The results presented demonstrate however that non-invasive and non-radioactive real time monitoring of drug metabolism in intact organs is possible.

Animals↗
PubMedDate not supplied

Determination of sulfamethazine in swine and cattle feed by reversed-phase liquid chromatography with post-column derivatization: pre-collaborative study.

In-house validation of a liquid chromatographic method for determination of sulfamethazine in swine and cattle feed was performed to verify that the method was ready for collaborative study under AOAC INTERNATIONAL guidelines. In this method, sulfamerazine is added during the extraction procedure and is used as an internal standard to correct for variable recovery of sulfamethazine from a variety of swine and cattle feed matrixes. The determinative step involves the use of post-column derivatization with dimethylaminobenzaldehyde which reacts with the primary amine group on the sulfonamides. Detection is at 450 nm, a wavelength at which most co-extracted matrix materials and other feed additives do not absorb light. The results indicate that the method recovery, precision, and ruggedness meet normal criteria to be ready for a collaborative study. Fortification experiments over a range of sulfamethazine concentrations from 0.006 to 0.26% showed an overall recovery relative to the internal standard of 100 +/- 2%. These studies include both swine and cattle feed matrixes. The mean recovery in the analysis of 3 beef cattle experimental feeds was 98.9%. The method results agreed with the AOAC INTERNATIONAL Official Method for colorimetric analysis of swine feed. Method precision was excellent during in-house validation studies, with coefficients of variation (CVs) ranging from about 0.5 to 3%. The method ruggedness was verified with an overall CV of 3.5%.

Animal Feed↗
PubMedDate not supplied

Determination of sulfamethazine in swine and cattle feed by reversed-phase liquid chromatography with post-column derivatization: collaborative study.

A liquid chromatographic (LC) method for the analysis of sulfamethazine (SMT) in complete swine and cattle feed was collaboratively studied. The method uses post-column derivatization with dimethylaminobenzaldehyde and detection at 450 nm. To 5g finely ground feed, extractant (0.2N HCl + 1.5% diethylamine in 25% methanol), and internal standard solutions are added, and the SMT is extracted by shaking for 1 h. Clarified extract (high-level sample extract diluted to a target concentration of ca 5.5 microg/mL) is chromatographed on a Cla reversed-phase LC column with acetonitrile-2% acetic acid (17 + 83) mobile phase. Sulfamerazine is used as an internal, or surrogate standard to correct for variable recovery of sulfamethazine from a variety of feed matrixes. Six Youden matched-pair samples were sent to 10 collaborators in Korea, Canada, and the United States. Label claims on the commercial feeds ranged from 0.0077 to 0.22% SMT. The SMT mean recovery as determined from the 5 samples with known analyte content was 99.8%. The within-laboratory relative standard deviation (repeatability) ranged from 0.28 to 4.72%. Among-laboratory (including within-laboratory) relative standard deviation (reproducibility) ranged from 1.26 to 4.87%. The authors recommend the method for AOAC INTERNATIONAL Official First Action status.

Animal Feed↗
PubMedDate not supplied

Correlation between plasma physostigmine concentrations and percentage of acetylcholinesterase inhibition over time after controlled release of physostigmine in volunteer subjects.

Five to six subjects ingested doses of controlled-release physostigmine salicylate tablets (9, 12, and 15 mg) followed by sequential blood drawing for measurement of plasma physostigmine concentrations and percentage of acetylcholinesterase (AChE) inhibition. Both plasma physostigmine concentrations and percentage of AChE inhibition demonstrated dose proportionality to three doses of ingested drug. Plasma physostigmine concentrations correlated with percentage of AChE inhibition across time by dose and across all doses and subjects tested. These data should be helpful to physicians in adjusting physostigmine dosing, enabling them to use the relatively simple and widely available AChE assay to approximate plasma physostigmine concentrations.

Adult↗