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Biomedical subjects

A van Enk

Publications and source records attributed to A van Enk.

At least 19 recordsLinked to original sources
PubMed1994

Serum distribution of two contraceptive progestins: 3-ketodesogestrel and gestodene.

A cross-over study of two oral contraceptive formulations, containing 30 micrograms ethinylestradiol in combination with 150 micrograms desogestrel (Marvelon) or 75 micrograms gestodene (Femovan), has been performed to compare the serum distribution and pharmacokinetics of gestodene and the active metabolite of desogestrel, namely 3-ketodesogestrel. Serum concentrations of both sex hormone-binding globulin (SHBG) and corticosteroid-binding globulin (CBG) were also measured and were increased more than 3-fold and 2-fold, respectively, on day 21 of the treatment cycle, with no statistically significant difference between treatment groups. In addition, 35 days after ingestion of either oral contraceptive had ceased, the serum SHBG and CBG concentrations were similar to the pretreatment values. During treatment cycles, increased serum SHBG levels were associated with a redistribution of 3-ketodesogestrel and gestodene such that the non-protein-bound (NPB) and albumin-bound fractions were reduced in concert with an increase in the relative proportions bound to SHBG. The proportion of gestodene bound to SHBG was consistently higher than that observed for 3-ketodesogestrel, and this undoubtedly reflects the higher affinity of SHBG for gestodene (Kd = 1.2 nM at 37 degrees C) when compared to 3-ketodesogestrel (Kd = 4.7 nM at 37 degrees C). It also probably accounts, in part, for the much higher total serum levels of gestodene (8.58 nmol/L) when compared to 3-ketodesogestrel (2.37 nmol/L) during the treatment cycles. Consequently, the absolute amounts of NPB, non-SHBG-bound, and SHBG-bound gestodene are significantly higher than those measured for 3-ketodesogestrel. It is concluded that ethinylestradiol-induced increases in serum SHBG levels during treatment with Marvelon or Femovan, influenced the distribution and total amount of 3-ketodesogestrel and gestodene in serum, respectively, and that this, combined with the higher affinity of SHBG for gestodene, results in a greater amount of bioavailable gestodene compared to 3-ketodesogestrel, despite the smaller dose of gestodene administered.

Adult↗
PubMed1994

The effect of two regimens of hormone replacement therapy on the haemostatic profile in postmenopausal women.

The effect of two different regimens of hormone replacement therapy on coagulation and fibrinolysis was measured in 30 women taking Tibolone (Livial) and 30 taking oestradiol valerate, sequentially combined with cyproterone acetate (Climen). Blood samples were taken before the beginning of the medication, then six and twelve months afterwards. The Livial group showed a rise of fibrinolytic activity as measured by the alpha 2-antiplasmin-plasmin complexes. Tissue plasminogen activator antigen and plasminogen activator inhibitor-1 decreased simultaneously. No effect was seen in the coagulation variables. In the Climen group no significant alterations were noticed, either in the coagulation or in the fibrinolysis variables. In the direct comparison of both substances only factor VII appeared to be significantly higher in the Climen group after six months and one year of treatment.

Anabolic Agents↗
PubMed1994

Uterine rupture. A seat belt hazard.

A case is described of a uterine rupture resulting from a car accident occurring in a woman who was wearing a seat belt as generally recommended. The rupture was initially not recognised and only became apparent after attempts to induce labor which led to expulsion of the fetus into the abdominal cavity.

Accidents, Traffic↗
PubMed1993

[Obstetrical outcome in teenage pregnancies in The Netherlands].

OBJECTIVE: To compare the course of teenage pregnancies and deliveries with that in women between the ages of 20 and 29. DESIGN: Observational. SETTING: The Netherlands. METHOD: Using data from the 1989 National Obstetric Database (LVR), 4500 teenage pregnancies were studied, to compare the risk of preterm birth, low birth weight and delivering a small for gestational age (SGA) baby between teenagers and older women. RESULTS: Women between the ages of 13 and 19 ran one and a half times as high a risk of having a preterm baby as women between the ages of 20 and 29 years (p < 0.0001). The risk of intrauterine death was 4 times as high for age 13-17 and 2 times as high for age 18-19 compared with older women (p < 0.0001). These results were found for teenage mothers of Dutch origin as well as for young mothers of foreign descent. Deliveries by teenagers were more often spontaneous, were of shorter duration and less often needed assistance than deliveries in older mothers (p < 0.001). CONCLUSION: Even in the Netherlands, with the lowest teenage pregnancy rate in the Western world and a prenatal care system generally considered of high quality, teenage pregnancies have less favourable outcomes than those in older women. Since we had no information on cultural background, socioeconomic status or life style, further research into determinants of outcomes of Dutch teenage pregnancies is indicated.

Adolescent↗
PubMed1993

Vaginal uterine amputation.

Since sexual dysfunction after hysterectomy might be prevented by leaving the portio in place, a technique was developed to perform vaginal uterine amputation. The method appeared to have been described already 40 years ago but has vanished from textbooks since then.

Amputation, Surgical↗
PubMed1993

Maternal death due to acute necrotizing colitis in homozygous sickle cell disease.

The case history is described of a 21-year-old female with homozygous sickle cell disease and fatal postpartum haemorrhage from the colon. At autopsy many sickled cells were found in the arterioles of the mucosa and submucosa in combination with necrotic lesions and ulcerations of the sigmoid colon. A causal association between occlusion of blood vessels by sickled cells and the occurrence of vascular necrosis of the sigmoid colon is suspected.

Acute Disease↗
PubMed1990

Some characteristics of labor in ethnic minorities in Amsterdam.

A retrospective study of labor in immigrants, subdivided into Blacks, Asians and Mediterraneans (Turks and Moroccans) and autochthonous Dutch in Amsterdam over a 10-year period showed definite differences. The second stage was shortest in Blacks and Mediterraneans but they sustained perineal tears and episiotomies less frequently. Differences in positions at birth were small except for occipito-posterior position which was very rare in Asians and Mediaterraneans. The rate of cesarean section was highest and that of instrumental vaginal delivery lowest in Blacks, and latter being highest in Asians. Retained placenta occurred less often in immigrants than in Dutch.

Cesarean Section↗
PubMed1990

Bone mineral density after adjuvant chemotherapy for premenopausal breast cancer.

Lumbar bone mineral density (BMD) determination by dual photon absorptiometry was used to study the influence of adjuvant chemotherapy for premenopausal breast cancer on the risk of premature osteoporosis. Six cycles of combination chemotherapy caused ovarian failure in 31 of 44 (71%) women, amenorrhoea mostly already beginning during treatment. In contrast, only seven of 44 (16%) women, who were pair-matched for age and year of breast cancer surgery and had not been treated with chemotherapy, were post-menopausal at the time of measurement. The mean interval after breast surgery was 3.5 years. The significantly decreased BMD in the treated group (1.17 compared to 1.29 g cm-2) could only be explained by the high incidence of menopause in these women, which on average occurred 10 years prematurely. Extrapolation of these findings suggests that adjuvant chemotherapy may precipitate osteoporotic fractures by some 10 years in a considerable proportion of women cured of premenopausal breast cancer.

Adult↗