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Biomedical subjects

G Raab

Publications and source records attributed to G Raab.

47 records · Page 3Linked to original sources
PubMed1985

Monooxygenase induction by various xenobiotics and its influence on the rat liver microsomal metabolite profile of benz[a]anthracene.

Several pesticides (lindane, carbaryl, pentachlorophenol, DDT), polycyclic aromatic hydrocarbons (PAH) and heterocyclic analogues (fluoranthene, dibenz[a,h]anthracene, dibenz[a,h]acridine, indeno[1,2,3-cd]pyrene, 10-azabenzo[a]pyrene) and pharmaceuticals (diphenylhydantoin, ethinylestradiol, levonorgestrel) were tested for their potencies to induce monooxygenase activities in the rat liver by means of recording the metabolite profile of benz[a]anthracene in rat liver microsomal incubations. Some of them were found to be weak or moderate inducers, but even less efficient ones altered the benz[a]anthracene metabolite profile significantly. Only indeno [1,2,3-cd]pyrene stimulated the bay-region oxidation of benz[a]anthracene. A sex-dependent metabolism was observed in both untreated and contraceptive-pretreated Wistar rats.

Animals↗
PubMed1984

Open v closed reduction of the fractured nose.

A stepwise study of nasal fractures includes an initial investigation that was carried out to discover why so many patients were awaiting rhinoplasty, which led us to find a 30% to 40% failure rate in nasal manipulation operations. We then studied the mechanics of nasal fracture by striking fresh cadaver noses. We found that if the nasal bones were deviated by more than half the bridge width, there was a concomitant C-shape fracture of the bony and cartilaginous septum. Two trials were performed, and patients with nasal deviation after trauma were allocated to either manipulation or manipulation plus excision of septal cartilage (closed or open reduction). Both trials were statistically significant, indicating that open reduction is the preferred treatment for patients with a deviation of more than half the bridge width of the nose.

Adult↗
PubMed1983

Induction of specific monooxygenases by isosteric heterocyclic compounds of benz[a]anthracene, benzo[c]phenanthrene and chrysene.

Benzo[c]phenanthrene and a series of heterocyclic compounds (benzo[b]naphtho(1,2-d)thiophene; benzo[b]naphtho(2,1-d)thiophene; benz[a]acridine and benz[c]acridine) were tested to their capacity of inducing monooxygenase activity in rat liver by means of recording the metabolite profile of benz[a]anthracene formed in rat liver microsomal incubations. Although all compounds tested were found to be weak monooxygenase inducers the pretreatment of rats with them resulted in significant changes of the microsomal metabolite profile of benz[a]anthracene. The thiophenes equally gave rise to oxidation at the 5,6- and the 8,9-positions, whereas the benzacridines being isosteric to benz[a]anthracene favoured the K-region oxidation (5,6-oxidation). A structure-dependent effect of monooxygenase inducers on the metabolite profile of benz[a]anthracene is discussed.

Animals↗
PubMed1982

On the metabolic activation of benz[a]acridine and benz[c]acridine by rat liver and lung microsomes.

The metabolism of benz[a]- and benz[c]acridine by liver and lung microsomes from untreated, phenobarbital (PB)-treated and benzo[k]fluoranthene (BkF)-treated rats has been studied by gas chromatography/mass spectrometry (GC/MS). Epoxidation and hydrolysis of the epoxides to dihydrodiols were found to be the predominant pathways for all substrates. N-Oxidation is likely to occur in the case of benz[c]acridine. However, no unequivocal evidence could be obtained for the formation of the ultimate carcinogens--the t-3,4-dihydrodiol-1,2-epoxides--in case of both benz[a]- and benz[c]acridine. K-Region oxidation was induced by phenobarbital, whereas the formation of non-K-region metabolites increased after BkF treatment in the case of benz[c]acridine.

Acridines↗
PubMed1982

The metabolism of pyrene by rat liver microsomes and the influence of various mono-oxygenase inducers.

1. Pyrene metabolite g.l.c. profiles were recorded and metabolites identified by mass spectrometry. 2. Pyrene is metabolized by liver microsomes of untreated rats to 1-hydroxypyrene, 4,5-dihydroxy-4,5-dihydropyrene, two different diphenols and a triol, tentatively identified as 1,4,5-trihydroxy-4,5-dihydropyrene. 3. Pretreatment with phenobarbital or polychlorinated biphenyls favours oxidation at the K-region, whereas cytochrome P-448 inducers stimulate oxidation at the non-K-region of pyrene. 4. 1-Hydroxypyrene does not inhibit pyrene oxidation. 5. Pyrene diphenols are formed by secondary oxidation of 1-hydroxypyrene. 6. Triols are formed from dihydrodiols by secondary oxidation.

Animals↗
PubMed1981

Endocrine assessment of the subfertile male.

Sixty-three male (XY) patients attending a subfertility clinic with average sperm density under 40 million/ml were studied by testicular biopsy and multiple basal estimations of plasma LH, FSH, testosterone as well as LHRH (50 micrograms i.v.) stimulation. A further forty patients with similar sperm densities also had testicular biopsy but only single estimations of the three hormones. A single basal FSH was found to be the best discriminator of testicular histologies. Patients with testicular biopsies showing germ cell aplasia in some or all seminiferous tubules (grades 3 and 4) had significantly higher basal FSH than those with hypospermatogenesis, germ cell arrest or normal appearance (grades 1 and 2). Basal FSH also showed a linear trend rising with decreasing sperm density but only rose above the normal range when sperm densities fell below 1 million/ml. When basal FSH, testicular histology and sperm density were considered together in the whole group (n = 100), high levels of FSH accurately indicated the presence of germ cell aplasia in some or all seminiferous tubules in azoo- and oligospermic men with sperm density under 5 million/ml. Normal FSH and azoospermia is diagnostic of obstruction in the excurrent ducts, and further investigation is undertaken if surgical correction of the obstruction is contemplated. Hormone estimations are not helpful in oligospermic patients with average sperm density over 5 million/ml. On the basis of these findings it is suggested that there is little place for the LHRH test in the routine assessment of male subfertility. Testicular biopsy is indicated only in oligospermic patients with average sperm density under 5 million/ml and normal basal FSH.

Adult↗
PubMed1980

Gonadal-pituitary hormone levels in gynaecomastia.

Plasma levels of LH, FSH, oestradiol 17 beta and testosterone were measured in twenty-two men with gynaecomastia. The group was divided by age into those under and those over 50-years-old and the mean hormone levels of the two groups were compared with two groups of age-matched normal men. In the young men with gynaecomastia LH and consequently the LH:FSH ratio was lower than in controls. Older patients with gynaecomastia had higher values of both LH and FSH than normal controls but the LH:FSH ratio was similar in the two groups. A pulsatile pattern of LH was present only in the young controls. Older controls had higher FSH levels than younger controls. In older men with gynaecomastia oestradiol levels and the oestradiol:testosterone ratio were higher than in those without.

Adolescent↗