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Biomedical subjects

J Müller

Publications and source records attributed to J Müller.

At least 667 records · Page 37Linked to original sources
PubMed1984

[Clinico-pharmacological studies on the course of high-dose methotrexate therapy in childhood. A retrospective comparison of centers].

In a retrospective study with comparison of two centres (Homburg and Munich) the response of 91 cycles of high-dose methotrexate treatment (4.2-13.6 g/m2 body-surface) was assessed in eight children with osteosarcoma and one with chondrosarcoma. Accompanying treatment (alkalization, infusion and leucovorin "rescue") was undertaken to reduce the methotrexate serum level 48 hours after infusion to below 0.4 mumol/l and thus avoid toxic effects. In the course of these treatment cycles there was a fall in urinary pH values below 7.0 in 59% (Homburg) and 75% (Munich) treatment cycles. On average there were lower methotrexate serum levels 24 and 48 hours after methotrexate administration among the Homburg patients than those in Munich. If urinary pH values fell to below 7.0, a decrease in leucocyte count below 2,000/mm3 was observed in 65% and 70%, respectively. The data indicate the need of carefully measuring urinary pH and methotrexate serum concentration during high-dosage methotrexate treatment and thus decrease the danger of bone-marrow damage.

Adolescent↗
PubMed1984

Differential rearing experience, gender, and radial maze performance.

Since both differential rearing and gender have been known to affect maze abilities, the present study examines the performance of male and female hooded rats raised from weaning in either a complex environment (EC) or isolated environment (IC) on the 17-arm radial maze. In two separate replications, EC rats learned the maze more quickly and accurately than IC rats, as assessed by total errors, the number of correct choices to the first error, and the number correct in the first 17 choices. However, EC rats were more likely than IC rats to employ an adjacent-arm strategy which may have contributed to their superior performance. There were no gender differences or environment by gender interaction effects on any measure of accuracy or adjacent arm strategy in either replication. It appears that the performance of both male and female rats on the 17-arm radial maze is similarly influenced by the rearing environment.

Animals↗
PubMed1984

Analysis of mast cells in rheumatoid arthritis and osteoarthritis by an avidin-peroxidase staining.

As demonstrated by labeling with peroxidase, avidin was found to bind selectively and distinctly to mast cell granules. Inhibition studies suggested that avidin is bound by heparin. Based on this new mast cell staining procedure, mast cell distribution in the inflamed synovium of rheumatoid arthritis (RA) and osteoarthritis (OA) has been investigated. In the subsynovial layer, a significant decrease in mast cell numbers was observed in RA-synovium when compared with OA-synovium. This decrease correlated with the presence of lining cell ulcers and granulation tissue and can be interpreted as the result of mast cell degranuation induced by complement-mediated or immune complex-triggered mechanisms.

Arthritis, Rheumatoid↗
PubMed1984

Sodium depletion of rats induces a mitochondrial protein in the zona glomerulosa of the adrenal cortex.

Sodium restriction of rats resulted in a marked increase in the concentration of a mitochondrial protein with a mol. wt of 49000 in the zona glomerulosa of the adrenal cortex. The same protein had been previously induced in potassium deficient rats by potassium repletion. Since both sodium depletion and potassium repletion are known to stimulate the activity of the mitochondrial mixed function oxidase involved in the conversion of corticosterone to aldosterone, the present observation supports the hypothesis that the potassium-induced protein might represent cytochrome P-450CMO (corticosterone methyl oxidase).

Adrenal Cortex↗
PubMed1984

Abnormal germ cells in maldescended testes: a study of cell density, nuclear size and deoxyribonucleic acid content in testicular biopsies from 50 boys.

We have studied the numerical density, nuclear size and deoxyribonucleic acid content of germ cells in consecutive testicular biopsies from boys with maldescended testes. Patient age ranged between 7.8 and 17.9 years. Of the biopsy specimens 16 (32 per cent) contained no germ cells, while in the remaining 34 specimens the number of germ cells per unit volume of tissue was considerably below normal. In all cases the mean nuclear size of the germ cells was above normal. The deoxyribonucleic acid distribution pattern of germ cell nuclei was abnormal in 17 of 19 cases investigated, exhibiting increases in the median and mean deoxyribonucleic acid content, and a higher fraction of cells with a deoxyribonucleic acid content above the normal diploid range. We conclude that germ cells in the cryptorchid testis are abnormal with respect to numbers but also in nuclear morphology, as indicated by increased size and deoxyribonucleic acid content. Thus, quantitative and qualitative changes of the germ cells may be of importance in impaired fertility associated with testicular maldescent. The significance of these observations in relation to the increased risk of development of germ cell neoplasia in maldescended testes remains to be investigated.

Adolescent↗
PubMed1984

Self-healing strategies among schizophrenics: attempts at compensation for basic disorders.

New experimental findings show that schizophrenics, as well as some of their non-schizophrenic relatives, manifest basic cognitive disorders defined in terms of variables from the field of experimental psychology. These basic disorders can be regarded as markers--if not, indeed, as psychological manifestations--of vulnerability to schizophrenia. They can be associated with subjectively experienced forms of non-clinically manifest impairments in psychological functioning. It was therefore hypothesised that schizophrenics, as well as non-schizophrenic subjects vulnerable to schizophrenia, will, in the course of learning processes, develop compensatory efforts which may be more or less effective. It is assumed that effective efforts of this kind will take on special significance in stress situations which would tend to elicit the occurrence of a schizophrenic episode. Effective efforts at compensation for basic disorders should be able to act as a 'buffer' against negative stressor effects (moderator function), thus reducing the danger of a psychotic breakdown. These compensation efforts were studied in 40 inpatients in remission after an acute schizophrenic episode. It was found that significant correlations exist between the extent of subjectively experienced basic disorders and the number and kind of conscious compensation attempts. Although the findings to date are of a preliminary and purely descriptive nature they would seem to justify further research.

Adaptation, Psychological↗
PubMed1984

Role of the renin-angiotensin system in the regulation of late steps in aldosterone biosynthesis by sodium intake of potassium-deficient rats.

The role of the renin-angiotensin system in the adaptation of late steps in aldosterone biosynthesis to sodium intake was studied in potassium-deficient rats. Capsular portions of adrenal glands were incubated with [3H]corticosterone and conversion to aldosterone and 18-hydroxycorticosterone was measured by double isotope dilution and multiple paper chromatography. Sodium loading of sodium- and potassium-depleted rats resulted in a rapid and extensive fall in PRA but only in a delayed and gradual suppression of aldosterone biosynthesis. Treatment with the converting enzyme inhibitor, captopril, did not affect aldosterone biosynthesis in rats with established sodium and potassium deficiency, but blocked the stimulation of the conversion of corticosterone to aldosterone and 18-hydroxycorticosterone by sodium restriction of potassium-depleted rats. Infusion of a high dose of angiotensin II into potassium-deficient rats stimulated aldosterone biosynthesis depending upon the concurrent sodium intake. Accordingly, the renin-angiotensin system plays an important but limited role in the control of late steps of aldosterone biosynthesis by sodium intake. Angiotensin II seems to be essential for the induction but not for the maintenance of a high activity of the enzyme(s) involved in the conversion of corticosterone to aldosterone during combined sodium and potassium restriction. The sensitivity of the zona glomerulosa to the long term stimulatory action of angiotensin II varies with the sodium intake and appears to be regulated by the plasma potassium concentration and unknown other mediators.

18-Hydroxycorticosterone↗
PubMed1984

Morphometry and histology of gonads from twelve children and adolescents with the androgen insensitivity (testicular feminization) syndrome.

Gonadal histology was investigated by means of stereology and Conventional microscopy in 12 patients, aged 2 months to 19 yr, with the androgen insensitivity syndrome (AIS). Eight patients had the incomplete variant of the syndrome and 4 patients had the complete form. Testicular tissue was removed as a prophylactic measure in all patients. In 6 patients less than 5 yr of age testicular histology was normal, except for slightly decreased mean tubular diameters, and, in 1 of the patients, abnormal morphology of the germ cells including a carcinoma-in-situ pattern. The number of germ cells was within the normal range in these 6 patients. In contrast, in older patients (greater than 7 yr of age), germ cells were absent or present only in small foci. In patients with the complete AIS the testicular histology also was immature after puberty, whereas some maturation and subsequent degeneration was found in adolescent patients with the incomplete form of the syndrome. In addition, 2 of these latter patients had a carcinoma-in-situ germ cell pattern. Although patients with the AIS have no reduction of the number of germ cells during the first years of life, this syndrome is associated with abnormal morphology of the germ cells, including patterns of carcinoma-in-situ and impaired pubertal maturation of the seminiferous tubules and the germ cells, in older patients.

Adult↗
PubMed1984

Fluctuations in the number of germ cells during the late foetal and early postnatal periods in boys.

Previous studies have shown marked elevations of serum concentrations of follicle stimulating hormone, luteinizing hormone, and testosterone during the first 6 months of life in boys. We have carried out a quantitative study of the changes in the total number of germ cells in 46 pairs of autopsy testes from normal boys between 28 weeks of gestation and 1000 days of postnatal life. The study demonstrated an increase in the total number of germ cells in boys up to 100 days of age (Spearman rho = 0.62, P less than 0.01), and a successive decrease in boys older than this age (Spearman rho = -0.56, P less than 0.01). Thus a peak in the total number of germ cells per boy was found somewhere between day 50 and 150 after birth, and the course of this variable was similar to that previously reported on the hormonal concentrations in serum.

Age Factors↗
PubMed1983

Importance of tyrosine for structure and function of mitochondrial malate dehydrogenases.

Mitochondrial malate dehydrogenase from pig and chicken both contain one tyrosine/subunit with highly red-shifted spectrum, most probably involved in a hydrogen bond with a carboxylate group. The spectral changes of this tyrosine can be used as an indicator for alkaline denaturation, acid transition and coenzyme binding. Acid transition is coupled with breaking of this bond by protonation as monitored by loss of absorbance at 290 nm. Activity is lost and fluorescence intensity is increased at slightly higher pH, thus indicating increased mobility of the indicator and most probably of the whole protein prior to protonation of the indicator-tyrosine.

Animals↗