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Biomedical subjects

M Knoll

Publications and source records attributed to M Knoll.

59 records · Page 4Linked to original sources
PubMedDate not supplied

Antimutagenic effects on male germ cells of mice.

The alkylating agent cyclophosphamide (CPA) and the antioxidant ethoxyquin (EQ) were administered perorally to NMRI mice. The strong clastogenic action of CPA on spermatogonia was diminished by simultaneous doses of EQ. Higher doses of the antioxidant produced greater anticlastogenic action. Furthermore, the action of the mutagen and the antioxidant on the late spermatids and the spermatozoa was observed using the dominant lethal test. The antioxidant had only a weak influence on these postmeiotic stages.

Administration, Oral↗
PubMedDate not supplied

Cigarette smoke inhalation affects the reproductive system of female hamsters.

The purpose of this study was to determine if inhalation of mainstream (MS) or sidestream (SS) smoke affects the reproductive organs of female hamsters. Females inhaled smoke from one or two cigarettes twice per day for 30 d prior to mating using a smoking machine equipped for nose breathing. Serum cotinine levels were within the ranges found in active and passive humans smokers. On day 7 of pregnancy, the reproductive organs of controls and smokers were evaluated for the total number of corpora lutea (CL), the percentage of normal, pink, and small CL, the vascular area in the CL, the ultrastructure of the oviductal epithelium, the ratio of ciliated to secretory cells in the ampulla of the oviduct, the stretchability of the uterine horns, the percentage of implantation sites, and the percentage of touching implantation sites. All parameters, except the percentages of implantation sites and of small CL, were affected by exposure to smoke. To determine if the effects of smoking on the ovary and uterus could be reversed, females smoked for 30 d, remained in their cages without smoking for 30 d, and then were mated and evaluated on day 7 of pregnancy. In this reversal experiment, all ovarian and uterine parameters (except total CL) previously affected by smoking were normal in MS and SS females. These experimental observations show that components in both MS and SS smoke, when delivered at levels comparable to those human smokers receive, can affect the ovary, oviduct, and uterus.

Animals↗
PubMedDate not supplied

Cigarette smoke inhibits oocyte cumulus complex pick-up by the oviduct in vitro independent of ciliary beat frequency.

The purpose of this study was to quantify the effects of acute exposure to mainstream (MS) and sidestream (SS) smoke solutions on oocyte cumulus complex pick-up rate in explants of hamster oviducts using a newly developed in vitro assay. Experiments were performed in handmade perfusion chambers using infundibula from hamster oviducts and oocyte cumulus complexes harvested from mature ovarian follicles. Oocyte cumulus complex pick-up rate was measured by placing a stained oocyte cumulus complex at the base of the infundibulum and recording the length of time needed for the complex to traverse a defined path to the ostium. Addition of either whole MS or SS smoke solutions to the perfusion chamber caused a dose dependent decrease in oocyte cumulus complex pick-up rate. Unexpectedly, upon washout of smoke solutions with control medium, oocyte cumulus complex pick-up rate continued to decline. The gas phase of MS smoke is more inhibitory than the particulate phase, while SS gas and particulate phases inhibit oocyte cumulus complex pick-up rate at equivalent doses. Ciliary beat frequency and oocyte cumulus complex pick-up rate were measured using the same infundibular explants to determine if smoke solutions decrease oocyte cumulus complex pick-up rate by inhibiting ciliary beat frequency. Ciliary beat frequency decreased in MS smoke solutions and recovered either partially or completely after washout of the smoke solutions. SS smoke solutions either produced no change in ciliary beat frequency or stimulated ciliary beat frequency. Oocyte cumulus complex pick-up rate decreased in both MS and SS smoke solutions and further declined during washout when ciliary beat frequency was equivalent to or higher than controls. These data show that oocyte cumulus complex pick-up rate and ciliary beat frequency can be uncoupled and that smoke solutions inhibit oocyte cumulus complex pick-up rate by affecting factors in addition to ciliary beat frequency. Possible reasons for the smoke induced decrease in oocyte cumulus complex pick-up rate are discussed. These results may explain the increased incidence of tubal infertility and ectopic pregnancy observed in women who smoke.

Animals↗
PubMedDate not supplied

[Special considerations in dental surgery procedures on organ transplantation patients].

In 150 patients 366 (95%) of 385 dental surgery procedures performed prior to organ transplantations were free of complications. In 6 patients circumscribed wound infections occurred, and 5 post-operative hemorrhages as well as 2 injection hematomas were observed. In the group of patients where dental surgery was performed after organ transplantation, all 123 procedures were free of complications. Treatment of transplantation patients in the dental office requires a profound understanding of the complex clinical problems these patients might present, a good coordination of the required measures and close cooperation between the transplantation center and the attending dentist. Special considerations of the treatment of organ transplantation patients and the indications for dental surgery are discussed.

Adolescent↗