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Biomedical subjects

F Eichhorn

Publications and source records attributed to F Eichhorn.

14 recordsLinked to original sources
PubMed2002

Estradiol, testosterone, dehydroepiandrosterone and androstenedione: novel derivatives and enantiomers. Interactions with rat liver microsomal cytochrome P450 and antioxidant/radical scavenger activities in vitro.

Interactions of 27 steroids, among them 17 derivatives such as ethers, sulfates and amidosulfonates derived from 17 beta- and 17 alpha-estradiol, from testosterone and alpha- and beta-dihydrotesosterone and from dehydroepiandrosterone with rat liver microsomal cytochromes P450 (P450) were investigated in vitro by assessing binding to P450 and effects on P450 mediated monooxygenase functions as measured by different model reactions: ethoxyresorufin O-deethylation (EROD), ethoxycoumarin O-deethylation (ECOD) and ethylmorphine N-demethylation (EMND). With the exception of 17 alpha-estradiol-3-dimethylamidosulfonate, estrone, its -3-methylether and -3-amidosulfonate and testosterone, all other steroids displayed type I or reverse type I binding to P450. All steroids inhibited EROD activity in micromolar concentrations. An additional strong inhibition of ECOD and EMND activities was only demonstrated for the androgens and progestins. Estriol, estrone and mestranol displayed less inhibitory actions on the model reactions than estradiol. No major differences in comparison to the parent compounds were noted with the other derivatives. The only exceptions were 17 beta-(8,9-dehydro-14 alpha,15 alpha-methylene)estradiol, which displayed stronger effects than estradiol, and dehydroepiandrosterone-3-sulfate, which was less effective than dehydroepiandrosterone. Possible antioxidant properties of the steroids were examined by the stimulated lipid peroxidation (LPO), H2O2 production, and lucigenin (LC) and luminol (LM) amplified chemiluminescence (CL) using rat liver microsomes. Additionally, the influence on rat whole blood chemiluminescence (WB-CL) was assessed. All the estrogens, but not their methylethers and amidosulfonates inhibited LPO in micromolar concentrations. The effects on the other oxidase model reactions or on WB-CL were less distinct. Only ethinylestradiol and 17 beta-(8,9-dehydro-14 alpha,15 alpha-methylene)estradiol displayed a strong inhibitory action on all model reactions. With the exception of dehydroepiandrosterone-3-sulfate, which in general had only weak effects, the androgen and progestin derivatives, in contrast, strongly decreased H2O2 formation and LM- and LC-CL, but were mostly ineffective on LPO and WB-CL.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1998

Comparison of the response of human FaDu squamous cell carcinoma in nude mice after hypofractionated-accelerated regimens and "curative" fractionation schedules.

BACKGROUND: It has been suggested that tumors respond differently after irradiation with 10 or more fractions than with less fractionated regimens and that extrapolation from experiments with only a few fractions to "curative" regimens may be invalid. To test this hypothesis, we compared hypofractionated-accelerated treatments with "curative" fractionation schedules in human squamous cell carcinoma in nude mice. MATERIAL AND METHODS: FaDu tumors were transplanted subcutaneously into the hindleg of NMRI nu/nu mice. TCD50 values, i.e., the dose necessary to control 50% of the tumors locally, were determined after irradiation under ambient blood flow conditions with 5 and 10 fractions in 5 days, 10 fractions in 10 days, and 30 fractions in 15 days, 6 weeks or 10 weeks. RESULTS: TCD50 values of the hypofractionated regimens were not significantly different and varied from 41 to 46 Gy. The number of fractions given in the same overall time had no measurable effect on local tumor control. The TCD50 after 30 fractions in 6 weeks was 30 Gy higher than after the hypofractionated regimens. This effect was caused by a substantial increase of TCD50 with overall treatment time, the dose recovered per day was 0.82 Gy (95% CI 0.66; 0.96). alpha/beta eff determined from all data was 58 Gy (13; infinite). CONCLUSIONS: The results of the present study compare well with our previous findings after different "curative" fractionation schedules in the same tumor. Thus, our study does not support that tumors respond differently after application of 10 or more fractions compared to less fractionated regimens. The biological mechanisms that govern the radiation response of FaDu tumors appear to be the same for hypofractionated-accelerated and "curative" regimens. Since only one tumor was investigated, these results cannot be generalized at the present time.

Animals↗
PubMed1984

[The risk of cancer in neuropathic bladders].

Neuropathic bladder is on number six in a list of predisposing factors for bladder cancer. The incidence is reported to be between 0.25 and 9.7%. For these patients mortality is about twenty times higher than in patients with normal bladder function. Chronic infection of the urinary tract and long-term indwelling catheter increase the risk of cancer. Pure squamous cell and squamous cell carcinoma with elements of transitional cell carcinoma is noticed to be surprisingly frequent. In comparison, carcinoma in defunctionalized bladder is rare. For prophylaxis, instead of using a long-term catheter, intermittent catheterization is supposed to be applied as well as consequent cystoscopic examination once a year and 'mapping' of a neuropathic bladder which exists longer than 10 years.

Adult↗
PubMed1980

The time-distance diagram: a new method to analyze ureteral peristalsis by cineradiography.

We assessed ureteral peristalsis in dogs by cineradiography and analyzed the films in a single frame follow-up by measuring the position of bolus front and rear end in relation to the bladder and the kidney. The data were plotted as function of time in a time-distance diagram. The bolus rear end which is the active contractile rings, as proven by electromyography, travels with constant velocity. The bolus front shows remarkable changes in propagation velocity which can be explained by differences in wall forces that resist the opening of the ureteral lumen. Thus, the time-distance diagram describes precisely the constantly changing dynamics of ureteral peristalsis along the entire ureter.

Animals↗
PubMed1975

Gamma-glutamyl transpeptidase as an aid in the diagnosis of liver metastases.

Serum gamma-glutamyl transpeptidase (GGTP) activity was examined in 79 patients. Of these, 49 had diverse malignant tumors, some of which had metastasized to the liver, and 18 had benign diseases of the liver, gallbladder and bile ducts. Enzyme activity increased significantly in all but two patients in whom liver metastases were found. All but one of the patients with malignant tumors, but without liver metastases, showed normal GGTP activity. GGTP activity was elevated in all cases of jaundice. In the absence of jaundice, elevated GGTP activity is suggestive of the presence of liver metastases.

Adult↗
PubMedDate not supplied

[Enuresis--symptom of delayed micturition development or an obstructive urinary tract anomaly?].

In a review of the literature the question of origin of enuresis was studied. Most authors agree that diminished bladder capacity and involuntary detrusor contractions are the main cause of primary enuresis. Urodynamic investigations are necessary to differentiate developmental delay in bladder function form true anatomic infravesical obstruction. Therapeutic measures are successful in 2/3 of enuretics. Enuresis has a great tendency of spontaneous disappearance around 15% per year.

Adolescent↗