Search Results

You are looking at 1 - 10 of 16 items for

  • Author: H. J. van der Molen x
  • Refine by Access: All content x
Clear All Modify Search
Restricted access

H. J. van der Molen

ABSTRACT

A procedure for the quantitative determination of 5β-pregnan-3α-ol-20-one in urine is described.

After acid hydrolysis of the pregnanolone-conjugates in urine, the free steroids are extracted with toluene. Pregnanolone is isolated in a pure form as its acetate; after chromatographic separation of the free steroids on alumina, the fraction containing pregnanolone is acetylated and rechromatographed on alumina.

Quantitative determination of the isolated pregnanolone-acetate is carried out with the aid of the infrared spectrum recorded by a micro KBr-wafermethod.

The reliability of the method under various conditions is discussed under the headings, specificity, accuracy, precision and sensitivity. It is possible to determine 30–40 μg pregnanolone in a 24-hours urine portion with a precision of 25%.

Restricted access

H. J. van der Molen

Restricted access

H. J. van der Molen and D. Groen

ABSTRACT

Peripheral venous blood and erythrocytes from normal men and women, as well as from dogs, rabbits and sheep were incubated with 14C-labeled progesterone*, 20α-dihydroprogesterone, androstenedione and testosterone. The presence in blood and erythrocytes of a 20α-hydroxysteroid dehydrogenase activity, catalyzing the interconversion progesterone ⇄ 20α-dihydroprogesterone, and of a 17β-hydroxysteroid dehydrogenase activity, catalyzing the interconversion androstenedione ⇆ testosterone was observed. Incubation with washed erythrocytes in the presence of glucose and several co-factors favoured the formation of the reduced compounds: 20α-dihydroprogesterone or testosterone. Incubations with washed erythrocytes, without addition of glucose and co-factors, favoured the formation of the oxidized compounds: progesterone and androstenedione. Incubation of steroids with whole blood, resulted in metabolism of progesterone to 20α-dihydroprogesterone and of androstenedione to testosterone. The formation of the product during incubation in vitro increased linearly with time of incubation (15—180 min). Incubations of 20 ml blood or the equivalent amount of erythrocytes with substrate amounts of steroids varying from 0.5 to 3000 μg, gave a linear increase in the amount of product formed. The possible significance of these observations in vitro for steroid metabolism in vivo is discussed.

Restricted access

H. J. van der Molen and H. J. Bakker

ABSTRACT

Criteria are discussed which can be used for estimating whether there is an increase in uterine weight 18 hours after a single injection of a gonadotrophin solution in infantile mice.

It is of advantage to accept the quotient of uterine weight and body weight as a criterion, rather than the uterine weight. The effect of HMG20A with this rapid method is discussed. Prospects of using the rapid determination as a graded assay are good.

Restricted access

H. G. Wijmenga and H. J. van der Molen

ABSTRACT

14C-Mestranol (5 μc) was administered orally in a Lyndiol®**-tablet (= 5 mg lynestrenol*** + 150 μg mestranol) to four women using Lyndiol® during the lactation period shortly after delivery.

The concentration of radioactivity in the plasma and the excretion of radioactivity in the urine and milk were studied.

The clearance rate of radioactivity from the blood was very low. A halflife in the order of 40–60 h was found for labelled »mestranol and its metabolites«. In three cases 31–36% of the radioactivity was excreted into the urine within 5 days after oral administration of the labelled material; in the fourth patient this value was about 52 %.

During a collection period of 4 days after the oral administration of the 14C-mestranol-containing tablet, 0.0002–0.013 per cent of the administered dose was excreted into the milk. These very low values were partly due to the low amounts of milk that could be collected. It was calculated that with the regular oral administration of one Lyndiol®-tablet daily, with 150 μg mestranol per tablet, about 0.03–0.06 μg (0.02–0.04 % of the administered dose) of mestranol or its metabolites might be excreted per 100 ml milk. The significance of these amounts, in view of the transfer to infants during breast-feeding, is discussed.

Restricted access

H. J. van der Molen and M. J. Bijleveld

Restricted access

H. J. van der Molen and K. B. Eik-Nes

Restricted access

H. J. van der Molen and Miss U. W. Kleef

ABSTRACT

The occurrence, metabolic formation and degradation of 5β-pregnan-3α-ol-20-one are reviewed.

Estimation of 5β-pregnan-3α-ol-20-one in urine has shown that:

  1. under acid conditions 5β-pregnane-3α,17α,20α-triol is destroyed with partial formation of pregnanolone; however, the amounts of pregnanolone that are formed, do not interfere with the estimation of pregnanolone in urine of normal adults after acid hydrolysis and offer no explanation for the high levels of pregnanolone in urine of patients with adrenal hyperplasia, as observed by some investigators.

  2. Excretion of pregnanolone found in urine during pregnancy (1–15 mg/day) is considerably below the levels reported in the literature so far.

  3. Normal adults excrete pregnanolone in urine in amounts within a range of 0.05–0.70 mg/day.

  4. There is a positive rank-correlation between the excretion of pregnanolone and pregnanediol in urine of normal males and females and of pregnant females.

  5. After administration of ACTH to adults an increase in the excretion of pregnanolone in urine could not always be demonstrated.