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Biomedical subjects

J Buschmann

Publications and source records attributed to J Buschmann.

33 records · Page 2Linked to original sources

The effect of body temperature on the hypoxic fraction in mouse tumours.

General anaesthesia as well as mechanical restraint of animals, which is necessary to allow precise local irradiation of mouse tumours, is associated with a rapid drop in body temperature if no special precautions are taken to prevent it. This drop in body temperature leads to an increased sensitivity of the tumour to normoxic irradiation which, in the reported case, may be due to a decrease in the hypoxic fraction from about 20% to about 4% as a result of decreased oxygen consumption and increased tumour perfusion.

Anesthesia, General↗

The stopping of deuterons in lithium.

The interaction of 52 MeV deuterons with lithium was investigated, in view of the optimization of a lithium target for an intense neutron source based on the d-Li stripping reaction. The experimental results are compared with theoretical calculations obtained from an updated version of the Bragg code. This code describes in detail the interaction of charged particles with matter. Within the experimental uncertainties the theoretical results are well reproduced by the experiments.

Cyclotrons↗

Radiation-induced heart disease in rats.

After local irradiation of the rat heart with X ray doses of over 10 Gy (single dose), animals developed symptoms of radiation-induced heart disease, which at higher doses would lead to fatal cardiac failure. The LD 50 at 1 year was between 15 Gy and 20 Gy. The pericardium and epicardium responded to irradiation with exudative pericarditis after 4 months. Focal myocardial damage was secondary to progressive capillary damage.

Animals↗

Post mortem changes in drug-metabolizing enzymes of rat liver and human liver.

The aim of this investigation was to obtain information on the time-dependent decrease of the drug-metabolizing system in autolysing rat liver, and also in human cadaver liver. Rat liver, divided into three parts, was tested immediately after removal and 6 and 12 hrs later. Parameters investigated were: microsomal protein, cytochrome P-450, NADPH cytochrome C reductase, glucose-6-phosphatase, aminopyrine-N-demethylation and aniline-p-hydroxylation. In human liver, samples taken from 0.5 up to 3.5 hrs after death, microsomal protein cytochrome P-450, NADPH cytochrome C reductase and phospholipids were tested. Nearly all parameters based on microsomal protein decrease during autolysis, but by different amounts. Interestingly, the cytochrome P-450 content of patients with signs of shock 12 hrs before death is significantly lower than in patients without shock.

Adult↗

Alternative transport pathways of cholephilic 14C-hexobarbital metabolites in rats with experimental hepatitis and cholestasis.

Object of the investigation was to find out whether otherwise cholephilic metabolites are excreted via an alternative pathway into urine in experimental liver disease. Intraduodenal application of 14C-labelled hexobarbital in rats is followed by an immediate biliary excretion of metabolites in the range of 400 microgram/100 g bw/h. Using TLC these metabolites can be separated into a polar fraction (about 80% of total) and a non-polar fraction. Phenobarbital treatment leads to a decrease of the total biliary excretion of metabolites to about 200 microgram/100 g bw/h, the metabolite pattern remaining unchanged. Animals with a mild form of GalN-hepatitis had a moderate reduction of bile flow and a total metabolite output of 40 microgram/100/gbw/h. The metabolite pattern showed a decrease mainly of the polar fraction. In animals with an early stage of ANIT cholestasis a 50% reduction of bile flow was associated with a total metabolite excretion of only 20 microgram/100 g bw/h and polar metabolites were nearly absent. In both types of experimental liver disease in corresponding urine samples otherwise cholephilic metabolites appeared. The results obtained show that clinically moderate stages of experimental liver disease lead to a significantly diminished output especially of polar 14C-hexobarbital-metabolites into the bile, which can, therefore, appear in the urine instead.

1-Naphthylisothiocyanate↗

Harmonisation of rat fetal skeletal terminology and classification. Report of the Third Workshop on the Terminology in Developmental Toxicology. Berlin, 14-16 September 2000.

The initial efforts of the Federal Institute for Health Protection of Consumers and Veterinary Medicine (BgVV) and the Free University of Berlin to standardise terminology in the field of developmental toxicology began in 1995. Procedures were undertaken to harmonise the terminology used by the International Federation of Teratology Societies (IFTS) and the International Programme on Chemical Safety (IPCS). This article reflects these activities and is a report on the Third Workshop on the Terminology in Developmental Toxicology held in September 2000. This Workshop served as a forum to discuss the results of a survey on the classification of skeletal anomalies that had been previously sent to scientists active in the field. Although high agreement was reached among the evaluators for several terms, the use of a number of terms was rather variable. Therefore, the discussions at the workshop among the experts from research institutions, regulatory agencies, and industry were mainly focussed on those terms for which there was disagreement and/or uncertainties and the possible reasons. Pictures provided by the participants for the illustration of "grey zone" anomalies constituted the basis for detailed discussions. In many of the cases with lower agreement, decisions were facilitated by the provision of the corresponding picture. The main reasons for lower agreement were imprecise terms, insufficient knowledge on postnatal consequences, theoretical terms that are unlikely to occur in isolation, and the possibility of observing a range of severity that might be decisive for the classification of either a malformation or variation. The attendees concluded that "grey-zone" anomalies will never disappear completely and that for the assessment, the grade of severity and/or the frequency of the observation can be decisive for the terminology chosen. A Joint IPCS/IFTS Project was proposed to further consensus of terminology and classification and to link these anomalies to pictures at different skeletal sites. In order to support the harmonisation of regulatory decisions, it was proposed to establish a "Clearinghouse" System under the umbrella of the IPCS. The Clearinghouse could be contacted either by the regulatory authorities or by any company to clarify their queries, particularly with regard to registration or authorisation processes. Finally, it was recommended to also carry out a similar survey on "soft tissue anomalies" and "external findings." The results of this survey will be discussed at a Joint IPCS/IFTS Workshop in Berlin in 2002.

Abnormalities, Drug-Induced↗

Migraine patients show increased platelet vasopressin receptors.

This study was designed to investigate vasopressin receptor status (Bmax and Kd) on platelets, vasopressin plasma levels, and vasopressin-induced platelet aggregation in migraine patients (21 females and 6 males) during a headache-free interval and in a matched control group. In the migraine group, Bmax was significantly higher (P = 0.02) at 53.9 +/- 20.6 fmol/mg than in the control group (36.8 +/- 21.0 fmol/mg). A correlation between Bmax and high or low sensitivity to vasopressin as an aggregator was evident in the control group, but not in the migraine group. No differences in Kd or in plasma levels of vasopressin between the migraine and control group were apparent. Men in both groups were much less sensitive to vasopressin as a platelet aggregator than were women (P < 0.01). Whether the higher Bmax in the migraine group is a reflection of temporarily higher vasopressin levels during headache or reflects a primary increase in sensitivity to vasopressin, remains to be clarified. The higher sensitivity of platelets (as a model for vessel wall receptors) from women may indicate why many more women than men suffer from migraine. Since the Bmax of the vasopressin receptor on platelets from migraine patients is increased compared to controls, treating migraine headache with vasopressin may deserve more attention.

Blood Platelets↗

[Hyperthyroidism in early childhood and a very rare variant of glutaric aciduria: coincidence or causal relation?].

Hyperthyrosis is a rare disease in early childhood typically characterized by tachycardia, restlessness, elevated body temperature, failure to thrive, diarrhoea, goiter and a tendency to hyperglycaemia. A 3-year old boy presented with typical symptoms of thyrotoxicosis accompanied by ketotic hypoglycemia and excessively high glutaric acid excretion. To our knowledge this association has so far not been described. Specific defects responsible for glutaric aciduria types I & II were excluded. Our patient suffered from glutaric aciduria type III which was described once and is characterized by mild metabolic signs.

Age Factors↗