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Dive into the research topics where P. E. Schenck is active.

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Featured researches published by P. E. Schenck.


Physiology & Behavior | 1978

Effects of the menstrual cycle, social grouping, and exogenous progesterone on heterosexual interaction in laboratory housed stumptail macaques (M. arctoides).

A. Koos Slob; Michael J. Baum; P. E. Schenck

Abstract The effects of endogenous fluctuations in ovarian hormones during the females menstrual cycle on heterosexual interaction was studied in groups of stumptail macaques. When 5 different trios of females were paired for 5 consecutive weeks with each of 5 males no aspect of male-female interaction changed as a function of phase of the menstrual cycle. Moreover, males usually preferred to copulate with the same female of each trio in consecutive tests, regardless of the ovarian condition of any of the females. It appeared that the most dominant females in the trios were sexually most preferred. Subcutaneous implantation of silastic capsules containing progesterone into the sexually most preferred females of each trio affected neither the males sexual preference, nor the behavior of these females, nor the behavior of sexually non-preferred females in each trio. Likewise, progesterone in sexually preferred females had no effect on male-female interaction in pair tests. It is concluded that in stumptail macaques social factors are more important than ovarian hormones in regulating heterosexual interaction.


Fertility and Sterility | 1978

The duration of infertility: an important datum for the fertility prognosis of men with semen abnormalities.

Jacob H. Aafjes; Jan C.M. van der Vijver; P. E. Schenck

In a group of 584 men with semen abnormalities the relationship between conception and the duration of infertility was studied. Spontaneous pregnancies were reported significantly more frequently for men with an infertility duration of less than 2 years than for men with an infertility duration of more than 2 years. Seventy-three conceptions occurred spontaneously and sixty-six occurred while the men were undergoing different forms of therapy. When all pregnancies were considered together it appeared that the chance of fathering a child after 2 years of infertility was still about 20% during the ensuing 3 years.


Andrologia | 2009

Double-blind cross over treatment with mesterolone and placebo of subfertile oligozoospermic men value of testicular biopsy.

Jacob H. Aafjes; Jan C.M. van der Vijver; F.W. Brugman; P. E. Schenck

Doppelblind‐cross over‐Studie einer Therapie mit Mesterolon von Männern mit Oligozoospermie Die Bedeutung der Hodenbiopsie


Hormones and Behavior | 1986

Castration, sex steroids, and heterosexual behavior in adult male laboratory-housed stumptailed macaques (Macaca arctoides)

P. E. Schenck; A. Koos Slob

The sociosexual behaviors of six stable male-female pairs of stumptailed monkeys were studied in half-hour pair tests. Their performance before and after castration of the males was compared. The effects of replacement therapy with sex steroids on male-female interaction were studied. Also the effects of new females as sexual partners were investigated. Castration caused a significant decrease in sexual behavior. Individual males could display ejaculatory behavior up to about 1 year postcastration. Dihydrotestosterone propionate (75 mg/week/male) alone or in combination with estradiol benzoate (0.9 or 3 mg/week/male) was not effective in restoring sexual behavior to precastration levels in the three castrated males tested. Replacement therapy with testosterone propionate (75 or 10 mg/week/male) was effective in restoring copulatory behavior in half of the castrated males. In some males the introduction of a new female caused an increase in sexual activity, usually when sexual activity with their familiar partner was low. This occurred both in the castration condition and in the steroid treatment period, suggesting, that low activity was caused by low motivation and not by the inability to perform.


BMJ | 1978

Value of a testicular biopsy rating for prognosis in oligozoospermia.

Jacob H. Aafjes; J C van der Vijver; P. E. Schenck

Testicular biopsies of 142 oligozoospermic men were used to obtain a testicular biopsy score count. These scores were clearly related to the chance of fertility, in contra-distinction to data on hormone concentrations and from analysis of semen. In 36 patients with a score of 9-10 there were 15 pregnancies; in 59 patients with a score of 8-9, 12; and in 47 patients with scores below 8 there was only one successful pregnancy, though this last group also contained an additional three patients whose wives pregnancies ended in miscarriages. Rating of testicular biopsies is more useful for proper evaluation of oligozoospermic patients than are data on hormone concentrations and from semen analysis. Proper evaluation of new treatments should be based on trials where experimental and control groups are matched on these ratings.


Physiology & Behavior | 1981

Chemical castration with cyproterone acetate (Androcur®) and sexual behavior in the laboratory-housed male stumptailed maceque (Macaca arctoides)

A. Koos Slob; P. E. Schenck

Abstract Seven pairs of stumptailed monkeys were tested twice weekly (30-min behavior tests) and female-male interactions scored while males received IM injections of CA for 12 weeks, or oil vehicle. Paris served as their own controls. CA was injected in increasing doses: 6 weeks, 100 mg/week/♂, 2 weeks 150 mg/week/♂, 4 weeks 210 mg/week/♂. Serum testosterone levels were significantly lowered during CA, whereas serum cortisol was not affected by CA. Testis size also decreased with CA. Male sexual behavior (frequency of mounts and ejaculations) was increased significantly with CA. Sexual motivation, as measured by latency to first mount and to first ejaculation was not affected. During CA treatment the males became more social: they significantly groomed their female partner longer. This study also revealed striking intra-pair consistencies and inter-pair differences. It is concluded that cyproterone acetate does not diminish libido and potency in the male stumptailed monkey. It is discussed that in the human male CA probably does exert its sexual inhibition through anxyolitic-tranquilizing action, rather than through its hormonal action.


Behavior Research Methods | 1978

An automated device for measuring locomotor activity in rats

P. E. Schenck; H.P. van de Giessen; A. Koos Slob; J.J. van der Werff ten Bosch

An automated plus maze is described that is capable of recording the locomotor activity of 12 rats simultaneously. The system is built around an 8008 microprocessor chip from INTEL. The base of the system is formed by 12 plus mazes in which the activity of the animals under test can be monitored.


British Journal of Nutrition | 1980

Effect of neonatal undernutrition on serum follicle-stimulating hormone levels and ovarian development in the female rat

P. E. Schenck; A. Koos Slob; J. Th. J. Uilenbroek; J.J. van der Werff ten Bosch

1. Female rats were undernourished from birth through replacement for 12 h/d of the lactating mother by a nipple-ligated mother. This resulted in slow growth so that 22 d of age the body-weights equalled those of well-nourished animals at 14 d. 2. At 14, 17, 20 and 22 d groups of eight to ten animals each of undernourished and well-nourished rats were autopsied, serum follicle-stimulating hormone (FSH) concentration was determined by radioimmunoassay, uteruses were weighed and ovaries examined by light microscopy. 3. Undernutrition caused a 3-4 d delay in the third-week drop in serum FSH and in ovarian development as indicated by the numbers of antral follicles and by the maximal diameter of the ovaries and of the largest follicles. 4. It is postulated that the effect of undernutrition on serum FSH may be due to delayed increase in ovarian feedback effectiveness, which may be the result of either the retardation in ovarian development or a continued high level of serum oestrogen-binding protein. It remains uncertain through which mechanisms(s) undernutrition brings about delayed onset of puberty.


Fertility and Sterility | 1984

Comparison of photographic (multiple-exposure photography) and conventional evaluation of ejaculates for fertility prognosis

Jacob H. Aafjes; Robert Euser; P. E. Schenck

Semen obtained from 191 men visiting our infertility clinic was studied by MEP and conventional methods. With MEP, sperm count, percentage of motility, sperm velocity, straight line approach, and speed constancy were determined. Two years afterward 49 of the men appeared to have fertilized their partners. Between the fertile and infertile men, no differences in motility values determined by MEP could be detected. The only differences observed existed in sperm count and duration of infertility.


BMJ | 1978

Testicular biopsy in oligozoospermia

Jacob H. Aafjes; J C M v d Vijver; P. E. Schenck

as an anticonvulsant in fulminating preeclampsia. There seems to be a subconscious belief that diazepam is a hypotensive drug. This belief can be the only explanation for some of the massive doses of diazepam that are prescribed in fulminating pre-eclampsia, often far in excess of a reasonable anticonvulsant dose. The doctors anxiety at the failure of the blood pressure to fall results in his increasing the dose of diazepam; the blood pressure unsurprisingly remains elevated and the cycle is repeated. Thus doses of up to 160 mg of diazepam have been given to mothers in the 15 h before delivery in the absence of convulsions. Of course any anticonvulsant can be misused in this way, but diazepam is certainly the most popular. Chlormethiazole seems to have been used more rationally, usually in conjunction with recognised hypotensive drugs, and this has led to an impression that it has less depressant action on the fetus.2 The popularity of diazepam among British obstetricians is probably a reflection of its extreme popularity among the medical profession as a whole. Obstetricians should repeatedly be reminded, and should themselves remind their junior staff, that diazepam should not be prescribed in pregnancy with the freedom with which it is prescribed for the general population. A N P SPEIGHT

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A. Koos Slob

Erasmus University Rotterdam

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Jacob H. Aafjes

Erasmus University Rotterdam

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F.W. Brugman

Erasmus University Rotterdam

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H.P. van de Giessen

Erasmus University Rotterdam

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J. Th. J. Uilenbroek

Erasmus University Rotterdam

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Robert Euser

Erasmus University Rotterdam

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