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Biomedical subjects

V Zimmermann

Publications and source records attributed to V Zimmermann.

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

Percutaneous absorption, metabolism, and hemolytic activity of n-butoxyethanol.

A series of studies was conducted to examine the percutaneous absorption, distribution, excretion, and hemolytic activity of n-butoxyethanol (BE). Rats receiving a subcutaneous dose of 14C-labeled BE excreted the radioactivity in the urine (79%), expired air (10%), and feces (0.5%) within 72 hr. Of the organs analyzed, thymus and spleen showed elevated specific radioactivities as compared with blood. A percutaneous application of BE on rats, under nonocclusive conditions, showed 25-29% absorption within 48 hr. Peak blood levels of BE occurred at 2 hr after application; butoxyacetic acid (BAA) was found to be the major metabolite. Comparison of in vitro skin penetration data showed the following absorption pattern of BE: hairless rat much greater than pig greater than human skin. Hemolysis and associated hematological changes were noted in the rats which received single dermal applications of 260-500 mg/kg of BE. In vitro, BAA showed markedly greater hemolytic ability on rat erythrocytes than did BE. Human erythrocytes showed no hemolysis when incubated with BE or BAA at concentrations that are hemolytic to rat erythrocytes. An intravenous dose of 62.5 mg/kg of BE does not result in hemolysis or hemoglobinuria in the rat. The rat may be an animal model with increased susceptibility to the effects of BE compared with humans because of its rapid percutaneous absorptive ability and its greater hemolytic sensitivity.

Administration, Topical↗
PubMed1987

[Not Available].

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France↗
PubMed1985

Percutaneous absorption of formaldehyde in rats.

As formaldehyde is used as a preservative in cosmetic products, its dermal absorption from an O/W-cream was studied using rats. [14C]Formaldehyde as a tracer, together with non-labelled formaldehyde, was incorporated into a cream at a total concentration of 0.1%. Approx. 5% of the applied radioactivity was absorbed percutaneously within 48 h. Higher values were not found under occlusive conditions. The labelled substance was excreted primarily in urine and exhaled air. Further radioactivity was found in the carcass. Based on these results, a rough approximation was attempted of the amount of formaldehyde which could penetrate human skin after the application of a formaldehyde-containing cosmetic.

Animals↗
PubMed1985

[Not Available].

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History, Medieval↗
PubMed1982

[Not Available].

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Austria↗
PubMed1975

Resuscitation of the monkey brain after one hour complete ischemia. III. Indications of metabolic recovery.

Adult rhesus monkeys were subjected to complete cerebral ischemia for one hour and subsequent recirculation for up to 24 h. Animals with signs of functional recovery (e.g. spontaneous EEG activity) exhibited a partial replenishment of cellular energy sources (ATP, phosphocreatine) and a progressive normalization of cerebral lactate levels. Glucose and pyruvate concentrations showed a transient increase over control values during the early stages of postischemic recirculation. Monkeys without functional recovery lacked a significant resynthesis of energy-rich compounds; adenine nucleotides continued to decrease and lactate concentrations were higher than in animals subjected to ischemia without recirculation. Cerebral polysome profiles remained unaltered during the ischemic period but in all animals a marked disaggregation of polyribosomes with a concomitant increase in ribosomal subunits occurred after the onset of recirculation. In monkeys with indications of functional recovery these changes were reversible but a normal polysome profile was only observed after 24 h of recirculation. The results obtained indicate a postischemic depression of protein synthesis due to an inhibition of peptide chain initiation. After recirculation of the brain for 3-6 h there was evidence for an induction of enzymes involved in polyamine synthesis (ornithine decarboxylase and S-adenosylmethionine decarboxylase). No changes in the activity of these enzymes were observed at the end of the ischemic period, indicating that during complete cerebral ischemia not only the synthesis but also the catabolism of proteins is inhibited.

Adenosine Diphosphate↗
PubMed1975

Resuscitation of the monkey brain after one hour's complete ischemia. II. Brain water and electrolytes.

Adult normothermic rhesus monkeys were submitted to one hour's complete cerebral ischemia, followed by periods of blood recirculation varying from 45 min to 24 h. The functional impact of ischemia and the subsequent recovery was monitored by electrophysiological recording and a distinction was made between animals with signs of functional recovery and animals without recovery. Prior to ischemia the water content of the gray matter was 81.1 plus or minus 0.3% (mean plus or minus S.D.) and of the white matter 68.9 plus or minus 0.8%. The sodium-potassium ratio in the gray matter was 0.43 plus or minus 0.02 and in the white matter 0.62 plus or minus 0.06. During one hour's ischemia brain water did not change significantly, but the differences in the sodium-potassium ratio in white and gray matter were reduced. Blood recirculation of the brain after ischemia caused a considerable increase in brain water content and a shift in the sodium-potassium ratio up to 1.0. Calculated brain swelling was maximal after 45 min when it reached 11.1% of the total brain volume in an animal with recovery and 12.2% in another one without recovery. In animals with signs of functional recovery brain swelling rapidly diminished, followed by a more gradual normalization of brain electrolytes within 24 h. In animals without functional recovery electrolyte shifts were irreversible or even progressed further. It is concluded that brain swelling and electrolyte derangements following one hour's cerebral ischemia are fully reversible when signs of functional recovery appear and brain metabolism returns.

Animals↗