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Biomedical subjects

W de Wit

Publications and source records attributed to W de Wit.

9 recordsLinked to original sources
PubMed1998

Only hydrosalpinges visible on ultrasound are associated with reduced implantation and pregnancy rates after in-vitro fertilization.

A retrospective analysis of clinical and laboratory data was made of all in-vitro fertilization (IVF) patients with tubal pathology who had their first ever embryo transfer cycle between January 1st, 1992 and September 1st, 1996. The aim of the study was to determine the effect of the presence of a hydrosalpinx, whether or not visible by ultrasound, on pregnancy, multiple pregnancy and implantation rates in our patient population. The IVF success rate was also analysed by calculating cumulative ongoing pregnancy rates of the same patient group using the lifetime table approach. In the presence of an ultrasound-visible hydrosalpinx, rates of pregnancy and multiple pregnancy appeared reduced, but the differences were not significant. The rates of implantation, clinical implantation and ongoing implantation were significantly lower in the presence of an ultrasound-visible hydrosalpinx (odds ratios 0.33-0.46, C.I. 0.21-0.96). The cumulative chance of achieving an ongoing pregnancy after one or more IVF cycles was significantly reduced in the presence of an ultrasound-visible hydrosalpinx (relative hazard 0.36, C.I. 0.22-0.59). In the presence of a hydrosalpinx not visible by ultrasound the IVF outcome was not reduced. This retrospective study confirms that patients with hydrosalpinges have an impaired IVF outcome. Unique to this study and previously unobserved is the finding that there is a subgroup of patients with hydrosalpinges, those with ultrasound-visible hydrosalpinges, which is exclusively responsible for this impaired outcome.

Adult↗
PubMed1995

Chronic naltrexone treatment induces desensitization of the luteinizing hormone pulse generator for opioid blockade in hyperprolactinemic patients.

The aim of this study was to assess the possibility that ovulation might be induced in seven amenorrheic hyperprolactinemic women by treatment with naltrexone (50 mg/day) for 4-5 weeks. None of the patients ovulated. Increases in LH levels, LH area under the curve, FSH levels, and the number of LH pulses per 6 h were observed in all patients, 2-8 h after the beginning of naltrexone administration. However, all of these parameters had returned to the pretreatment range on day 7. The LH area under the curve, LH levels, FSH levels, and the number of LH pulses per 6 h on day 1 were significantly higher compared to the values on either day 0 (basal levels) or day 7. These data show that long term opioid receptor blockade induces desensitization of the hypothalamic-pituitary unit for the effects of opioid receptor blockade. Due to the induced desensitization, naltrexone is not an effective drug for ovulation induction in hyperprolactinemic patients.

Adult↗
PubMed1995

Endogenous proteolytic enzymes in chicken muscles. Differences among strains with different growth rates and protein efficiencies.

The theory that net muscle growth is, at least partly, regulated by catabolic factors has been tested in order to set up an animal model to study meat aging and post-mortem tenderization. Male and female chickens of a layer strain (White Leghorn), a commercial broiler strain (Ross), and two experimental broiler lines (designated GL and FC) were used to estimate differences in proteolytic enzyme activities in the breast muscles. The GL and the FC lines were selected for high body weight gain and high feed efficiency, respectively. At 6 wk of age the birds were slaughtered and the activities of endogenous proteinases and their specific inhibitors in breast muscles measured. The Leghorns showed significant differences in all traits compared with the three broiler genotypes. Within the broiler types, FC birds tended in the direction of the Leghorns and GL birds in the opposite direction. Ross birds were intermediate between FC and GL birds. All types and sexes differed significantly in slaughtering weight. Feed conversion ratio and protein conversion ratio were highest for Leghorns. The FC birds showed the lowest feed conversion. Ross and GL birds showed intermediate values. The Leghorns showed higher calpain activities and lower calpastatin activity than the three broiler genotypes. The FC broilers showed intermediate calpain and calpastatin activities but higher cathepsin H and total cystatin values. The GL broilers showed lower cathepsin B, D, and H activities. In all cases the Ross broilers showed intermediate values. From these figures it is concluded that the strains of birds used in this study can be used as a natural source of variability to study the mechanisms involved in post-mortem proteolytic degradation and thus in the study of muscle tenderization and meat aging. It is also concluded that it could be very interesting to study the behavior of the different proteolytic systems more carefully in relation to muscular growth characteristics and compare them to anabolic factors involved in muscle growth.

Animals↗
PubMed1992

[Weighing pros and cons].

An adequate, high-quality animal health service is indispensable to animal production in the Netherlands. Modern intensive animal husbandry, with its high density of animals, needs a considerable input of knowledge, vaccines and drugs. The consumer expects healthy and especially safe products. These two goals are in seeming contradiction. Moreover, veterinary help, the necessary use of drugs, the supervision and control of AID (Agricultural Inspection Services) and RVV (Inspection Service for Meat and Meat Products) add to the already substantial costs of modern animal husbandry. From the point of view of integral quality control, the question is what changes are necessary to achieve a more effective health service. Goals for the future include: reducing the structural dependence on drugs and additives; substantially reducing the number of active substances used; increasing consumer confidence in animal products.

Animal Husbandry↗
PubMed1991

CV 205-502, a new dopamine agonist, versus bromocriptine in the treatment of hyperprolactinaemia.

Forty-seven hyperprolactinaemic patients with serum prolactin (PRL) concentrations persistently above 1500 mU/l were treated with the new dopamine agonist CV 205-502 or bromocriptine in a prospective, randomized and double-blind fashion during a 24-week period. Two women had to be excluded because of poor compliance in the first month. Therefore 45 patients remained for evaluation. 81% of the patients in the CV 205-502 group and 70% of the patients in the bromocriptine group normalized their prolactin levels within the study period with a treatment dose as permitted in this protocol. In general serum prolactin normalized within 8 to 12 weeks of treatment. There were no differences between the two tested drugs regarding restoration of the menstrual cycle or disappearance of galactorrhoea. Both drugs gave rise to adverse reactions, especially during the initiation of therapy. However, the adverse reactions reported during CV 205-502 treatment were less severe and persistent than those attributed to bromocriptine. Patient acceptance of the new drug with regard to tolerability was judged by 90% of the women in that treatment group as very good or good, while 75% of those treated with bromocriptine evaluated its tolerability as very good or good. We conclude that CV 205-502 is highly effective in the treatment of hyperprolactinaemia with concomitant restoration of gonadal function and prevention of galactorrhoea. The tolerability of the drug seems better than of bromocriptine and therefore this drug is of value in the treatment of hyperprolactinaemic patients.

Adolescent↗
PubMed1984

Prophylactic bromocriptine treatment during pregnancy in women with macroprolactinomas: report of 13 pregnancies.

Ten women with a macroprolactinoma had prophylactic bromocriptine treatment during 13 pregnancies in the second and third trimesters. One patient had signs of tumour enlargement during the first trimester, but none of them showed tumour enlargement during prophylactic bromocriptine treatment. Prolactin levels were reduced in both maternal and cord sera, but they were normal in amniotic fluid. All pregnancies progressed to term. Thirteen healthy infants were born without congenital malformations and growth and psychomotor development were normal during the follow-up period (7 months to 5 years). The safety of bromocriptine treatment during pregnancy is discussed and our current policy of management of patients with prolactinomas is outlined.

Adult↗