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Biomedical subjects

G Hofstetter

Publications and source records attributed to G Hofstetter.

9 recordsLinked to original sources
PubMed2004

Cryopreservation of a whole ovary as a strategy for restoring ovarian function.

PURPOSE: To evaluate whether a total ovary can successfully be cryopreserved and thawed under maintenance of high proportions of structurally normal primordial follicles. METHODS: Porcine ovaries were explanted immediately after slaughtery. Ten ovaries were cooled to -196 degrees C using cryoprotective solution and a computer-controlled freezing technique. Five contralateral ovaries were fixed with formalin for histological examination, the five remaining ovaries were directly plunged in liquid nitrogen. After three weeks of storage, frozen ovaries were thawed and examined by light and electron microscopy. Viability was assessed by evaluation of intact primordial follicles with respect to cellular and intracellular structures. RESULTS: Histological viability of primordial follicles in computer-frozen ovaries was 84.4% (76.1-90.6%), as compared to non-frozen control samples (92-100%; mean 97.6%) and to ovaries plunged in liquid nitrogen without cryoprotection 21.1% (4.5-35.0%). CONCLUSIONS: Cryopreservation of whole ovaries may present a feasible way to maintain high numbers of viable primordial follicles in ovarian tissue retransplantation.

Animals↗
PubMed1999

The effect of smoking on oocyte quality and hormonal parameters of patients undergoing in vitro fertilization-embryo transfer.

PURPOSE: The aim of the present study was to investigate the influence of smoking on different parameters such as oocyte count, embryo score, and basal hormone values within the scope of in vitro fertilization-embryo transfer (IVF-ET). METHODS: Eight hundred thirty-four women undergoing IVF-ET treatment were classified as smokers or nonsmokers on the basis of questionnaires. Additionally, we divided them into three groups according to their stimulation protocol--"combined stimulation" [I; clomiphene citrate plus human menopausal gonadotropin (hMG)], "ultrashort" [II; gonadotropin releasing hormone agonist (GnRHa) plus hMG or follicle-stimulating hormone (FSH)], and "long downregulation protocol" (III)--and further classified again as smokers or nonsmokers within the groups. RESULTS: In general, smoking patients were significantly (P = 0.0195) younger than nonsmokers and showed a significantly (P = 0.0379) lower embryo score and a tendency (P = 0.0931) to produce fewer oocytes. There was no significant difference concerning the number of normally or pathologically fertilized and transferred oocytes and embryos suitable for cryopreservation. Women who smoked had significantly (P = 0.0112) higher basal 17-beta-estradiol (E2), luteinizing hormone (LH) (P = 0.0001), and dehydroepian-drosteronesulfate (DHEAS) (P = 0.0039) levels, but their basal human prolactin (HPRL) levels were significantly (P = 0.0033) lower than those of nonsmokers. According to the stimulation protocol used, we found the following results. Smoking patients in group I showed a significantly (P = 0.023) lower embryo score and produced fewer oocytes (P = 0.0113), with fewer of them being fertilized (P = 0.0072) and transferred (P = 0.0067). Women who smoked had significantly (P = 0.0002) higher basal LH levels, but their HPRL levels were significantly (P = 0.031) lower than those of nonsmokers. Furthermore, they had a thinner endometrium on the day of embryo transfer (P = 0.0366). In group II we measured significantly elevated basal E2 levels (P = 0.0089) and higher LH values (P = 0.0092) in smokers. Group III showed a trend (P = 0.0565) toward lower HPRL values in smokers. CONCLUSIONS: Although the fertilization rate of oocytes and the pregnancy rate were not significantly different between smokers and nonsmokers, we found significantly alterated hormonal parameters and negatively influenced oocyte parameters, particularly after clomiphene stimulation. So we might consider using only GnRHa protocols for smoking patients. Additionally, we advise our patients to stop smoking before an IVF-ET treatment because of the complex effects of smoking on the reproductive and hormonal system.

Adult↗
PubMed1999

[Ovarian tissue banking--primary results].

Lifelong hormone replacement therapy and infertility often follow oncological therapy in young women due to a dramatic reduction of the primordial follicle reserve. Reimplantation and function of frozen ovarian tissue slices were successfully demonstrated in animal models, but the durability is limited. Cryopreservation of a whole ovary could reestablish an almost normal ovarian function. Experiments with porcine ovaries showed histological viability. Cryopreservation and retransplantation of sheep ovaries should demonstrate success by hormonal response and pregnancy.

Animals↗
PubMed1993

Caffeine elimination in cirrhotic and non-cirrhotic liver disease of different etiology.

Caffeine elimination was studied in 419 patients with cirrhotic and noncirrhotic liver disease of different etiology (hepatitis B virus infection n = 79; hepatitis NANB virus infection n = 74; ethanol-induced liver damage n = 143; primary biliary cirrhosis I-IV n = 63; cryptogenic liver cirrhosis n = 60) following oral administration of 366 mg caffeine. Caffeine clearance in the control group was 69 +/- 33 ml/min (age-matched healthy volunteers and patients without liver disease). Caffeine clearance in acute hepatitis B (70 +/- 60 ml/min) chronic persistent hepatitis B (81 +/- 56 ml/min), chronic aggressive hepatitis B (107 +/- 66 ml/min), posthepatitic liver cirrhosis B (84 +/- 62 ml/min), acute hepatitis NANB (94 +/- 69 ml/min), chronic persistent hepatitis NANB (122 +/- 60 ml/min), chronic aggressive hepatitis NANB (87 +/- 52 ml/min) and posthepatitic cirrhosis NANB (59 +/- 26 ml/min) is not reduced in comparison with controls. In patients with alcoholic fatty liver (127 +/- 71 ml/min, p < 0.05) caffeine clearance is enhanced, in alcoholic hepatitis (57 +/- 72 ml/min) comparable to controls and in alcoholic cirrhosis reduced (36 +/- 44 ml/min, p < 0.05). In primary biliary cirrhosis I-IV caffeine clearance is higher than in controls (117 +/- 59 ml/min, p < 0.05). In cirrhotic liver disease of different origin caffeine clearance is inversely related to the serum bilirubin level. However, the absolute value is determined in addition by the underlying disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[One point determination of oral caffeine clearance in patients with liver diseases].

Caffeine clearance has been determined in 117 volunteers and patients (including 27 patients with liver cirrhosis) after oral application of 366.1 mg caffeine according to conventional pharmacokinetic methods (Cl = D/AUC). The resulting clearance values can be estimated with adequate accuracy from the plasma concentration at 12h for a concentration range of 2.0 to 6.5 mg/l according to Cl max = Doses/C 12h x t 12h x e and for concentrations higher than 6.5 mg/l according to Cl = Vd x (1n (D/Vd) - 1n C 12h/t 12h Vd is estimated from body weight as Vd = 0.42 x BW. "One - point" - estimation does not provide reliable data for plasma concentrations below 2.0 mg/l.

Administration, Oral↗
PubMed1987

Factors influencing the caffeine test for cytochrome P 448-dependent liver function.

Liver functions in patients with liver disease can be estimated by caffeine clearance. Our data, however, demonstrate the additional influence of factors other than liver disease on the caffeine test. Smoking enhances caffeine clearance in both healthy volunteers and patients with severe hepatic disorders, whereas co-medication with mexiletine strongly inhibits caffeine elimination.

Caffeine↗
PubMedDate not supplied

Effect of short-chain fatty acids on the human colonic mucosa in vitro.

Fermentable dietary fiber components are known to stimulate colonic crypt proliferation. As these compounds are rapidly degraded to short-chain fatty acids (SCFAs) by the anaerobic microflora, the hypothesis was tested that this trophic effect of fiber may be mediated by SCFAs. Biopsies were taken from normal cecal mucosa of 45 individuals during routine colonoscopy. They were incubated for 3 hours with sodium salts of SCFAs at physiological concentrations (three SCFAs = acetate 60 mmol/L + propionate 25 mmol/L + butyrate 10 mmol/L; acetate 60 mmol/L; propionate 25 mmol/L; butyrate 10 mmol/L) or equimolar NaCl (control). Cell proliferation was measured autoradiographically by subsequent pulse labeling with [3H]thymidine (1 hour). The labeling index (number of labeled cells divided by the total number of cells) was computed for the crypt as a whole and for five equal crypt compartments (compartment 1 = crypt base, compartment 5 = crypt surface). Cecal crypt proliferation was raised significantly in all incubation experiments with SCFAs. Butyrate (10 mmol/L, increase + 89%) and propionate (25 mmol/L, + 70%) were as effective in stimulating proliferation as the combination of three SCFAs (+103%), although the effect of acetate (+31%) was minor. Increasing the butyrate concentration to 25 mmol/L or 60 mmol/L did not result in a further increase of cell labeling. SCFAs stimulated proliferation in the basal three crypt compartments only. An expansion of the proliferative zone to compartments 4 and 5 was not observed. SCFAs, especially butyrate and propionate, are luminal trophic factors for the cecal epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗