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Biomedical subjects

K Boer

Publications and source records attributed to K Boer.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Prevalence of HIV antibodies in pregnant women in the Amsterdam HIV reference station research, 1988-1993].

Pregnant women were asked to undergo a HIV test in two hospitals, one maternity clinic (n = 12.784; 1988-1993) and one abortion clinic (n = 2089; 1990-1993) in Amsterdam, in order to establish trends in HIV prevalence. Participation rates were 92.4% and 84.4%, respectively. Among pregnant women the overall HIV prevalence was 0.27% (0.04% for pregnant women without a known HIV risk and 2.6% for women with a known HIV risk) and in the abortion clinic the overall HIV prevalence was 0.91%. The HIV prevalence over the years remained fairly constant. In the most recent years a slight rise was noticed in the HIV prevalence in the group pregnant women with a known HIV risk caused by an increase in the number of women from AIDS endemic countries in this group.

Adult↗
PubMed1995

Pregnancy outcome after transcervical CVS with a flexible biopsy forceps: evaluation of risk factors.

The pregnancy outcome of 1936 women who had transcervical chorionic villus sampling (CVS) with a flexible biopsy forceps was evaluated. Follow-up until 4 weeks after delivery was 99.4 per cent. Various patient- and procedure-related risk factors for spontaneous loss (fetal or neonatal death) were analysed using stepwise logistic regression analysis. The overall spontaneous loss rate was 4.5 per cent. Factors found to be significantly associated with spontaneous loss were quantity of villi < or = 15 mg (relative risk (RR) 2.13), a history of first-trimester miscarriage (RR 1.87) or delivery between 16 and 27 weeks (RR 3.87), cervical culture positive for anaerobes (RR 4.52) or group B streptococcus (RR 3.62), post-procedural bleeding > 3 days (RR 1.99), and multiple insertions (RR 2.64). Significant differences in loss rates between individual operators were found. A learning effect was not present. There were no infants born with terminal transversal limb anomalies in our series. We conclude that knowledge about significant risk factors for spontaneous loss after CVS is important both for obstetricians carrying out CVS procedures and for women seeking prenatal diagnosis.

Adult↗
PubMed1995

Circadian variation of urinary albumin excretion in pregnancy.

OBJECTIVE: The hypothesis was tested that circadian variations in urinary albumin excretion of pregnant women in the third trimester of normal pregnancy are different from nonpregnant individuals. DESIGN: Circadian variability in urinary albumin excretion was studied both in pregnant women and in nonpregnant controls either during normal daily activities or in contrast during continuous bedrest with standardised fluid and food intake to study endogenously generated rhythm. SETTING: Outpatient department and metabolic ward of a university hospital. MAIN OUTCOME MEASURES: Urinary albumin excretion during fixed time periods over the day and the night. RESULTS: Both ambulant pregnant and nonpregnant women have circadian rhythm in urinary albumin excretion but pregnant women have, firstly, a higher 24 h urinary albumin excretion, secondly, smaller relative day-night differences than nonpregnant controls and thirdly, in the metabolic ward some pregnant women demonstrate absence of rhythm. CONCLUSIONS: The higher albumin excretion during pregnancy in 24 h urine collections can largely be explained by a higher excretion during the night, compared with that of nonpregnant women. The day-night difference in urinary albumin excretion of ambulant pregnant women is exogenously determined.

Adult↗
PubMed1995

Similarity in env and gag genes between genomic RNAs of human immunodeficiency virus type 1 (HIV-1) from mother and infant is unrelated to time of HIV-1 RNA positivity in the child.

Variation in the env (V3 region) and gag (p17 region) genes of genomic RNA of human immunodeficiency virus type 1 was studied in three mother-child pairs. One infant was human immunodeficiency virus type 1 RNA positive at birth (pair 114), one became positive 6 weeks after birth (pair 127), and one became positive 30 months after birth (pair 564). The first two children were born to seropositive mothers, and the last child was infected by breast-feeding following seroconversion of the mother after delivery. In both V3 and p17gag, intrasample variability was much higher in the maternal samples, including the first seropositive sample of the seroconverted mother, than in the infants' samples. Variability was less in p17gag than in V3, except in the postnatally infected child. In all three cases, infection of the child was established by variants representing a minority of the cell-free virus population in the maternal samples. For the two infants born to seropositive mothers, V3 sequences were more similar to the sequence populations of maternal samples collected during pregnancy than to those of samples collected at delivery or thereafter. However, in pair 114 a V3 variant identical to the child's virus was also detected in the sample collected at delivery. In contrast to the V3 region, p17gag sequences of maternal samples of the first trimester of pregnancy and at delivery had comparable resemblance to the child's sequences in pair 114, while in pair 127, similarity to sequences of the sample collected at delivery was higher than that to sequences of the sample from early in pregnancy. In the last pair, V3 and p17gag sequences from a maternal sample collected 18 months prior to the first RNA-positive sample of the child resembled the infant's sequences as much as the sample collected close to the presumed time of infection. Taken together, the evolutionary characteristics for genomic RNA env and gag genes did not point to a particular time of mother-to-child transmission.

Amino Acid Sequence↗
PubMed1994

Radioimmunoassay of vasopressin during pregnancy. Use and removal of cystylaminopeptidase inhibitors.

This paper describes a radioimmunoassay (RIA) for arginine-vasopressin in which o-phenanthroline effectively inhibits cystyl-amino-peptidase activity in whole blood and plasma from pregnant women but in which o-phenanthroline is removed during the extraction of vasopressin from plasma to prevent disturbance of the RIA. Cystyl-amino-peptidase causes immediate degradation of vasopressin unless cystyl-amino-peptidase enzyme inhibitors such as o-phenanthroline are applied. However, o-phenanthroline interferes with RIA. We report an extraction procedure over octadecasyl silica-packed Sep-Pak C18 columns, by which cystyl-amino-peptidase as well as most of the cystyl-amino-peptidase inhibitor is removed from plasma with chloroform. The average o-phenanthroline concentration (0.25 mmol/l) found in the assay medium after extraction appeared not to interfere with the RIA. Polyacrylamide gel isoelectric focusing of extracts of platelet-rich and platelet-poor plasma from pregnant women revealed a single vasopressin immunoreactive peak in the RIA. Recovery and between-assay coefficients of variation of 3.2 ng/l vasopressin from pregnancy whole blood were comparable with non-pregnant controls (57%/8% and 59%/13%, respectively). Results with this assay compare well with those of another assay using inhibitors in pregnant subjects and with results in non-pregnant subjects.

Arginine Vasopressin↗
PubMed1994

The HIV prevalence among pregnant women in the Amsterdam region (1988-1991).

The objective of the study was to monitor the HIV prevalence in the years 1988-1991 among pregnant women in the Amsterdam region, visitors to an abortion clinic and 3 outpatient infertility clinics. All women attending these clinics were asked to participate in the study on a voluntary basis and were tested with informed consent. The women were questioned about risk-bearing behaviour of themselves and their sexual partner(s). In the period 1988-1991, of the 23,827 eligible pregnant women, 22,165 women participated (93.0%). Twenty-seven women were found to be positive for HIV antibodies (0.12%, 95% CI: 0.08%-0.17%), of whom twenty belonged to a known HIV risk group or had a partner who belonged to one of these groups and 7 women had no known HIV risk. Seventeen of the 27 women had a foreign nationality. The annual HIV prevalence among pregnant women was: 1988: 0.28%; 1989: 0.10%; 1990: 0.10%; 1991: 0.11%. In the years 1990 and 1991, of the 1,128 eligible women visiting the abortion clinic 953 (84.5%) were tested. Eleven women were HIV-seropositive (1.15%, 95% CI: 0.6%-2.0%), of whom 9 were from an AIDS endemic region, 1 woman had a partner from this region and 1 woman had no known HIV risk. Four African women had HIV-2 antibodies. At the 3 outpatient infertility clinics 1 woman was found to be HIV-positive (0.13%; 95% CI: 0.02-0.9). She had no other risk than a partner from an AIDS endemic area. In the Amsterdam region there was a steady and low HIV prevalence (0.1%) among pregnant women through the years 1988-1991. The prevalence in the abortion clinic was ten times higher. The program was able to detect possible high risk groups within the population. Migration and travelling can play an important role in the spread of HIV in the general heterosexual population.

Adult↗
PubMed1994

Cocaine use in pregnancy in Amsterdam.

To study the effects of cocaine use in pregnancy in Amsterdam, clinical data on cocaine-using pregnant women (n = 21) and their offspring (n = 23) were obtained retrospectively (1987-1994) at the Academic Medical Center, Amsterdam. Infants exposed to cocaine had a median gestational age of 39 weeks and a median birth weight of 3090 g. There were six preterm infants, two small-for-gestational-age infants and five infants with a small head circumference. Three infants had a congenital malformation. One infant (Potter's syndrome) died shortly before birth. One infant had congenital syphilis, four had intracerebral abnormalities on ultrasound and four had abnormal neurologic symptoms in the neonatal period. One infant died after 21 days of life. At follow-up four infants showed abnormal development. In 12 of the 23 infants (52%), one or more possible effects of cocaine were found.

Child of Impaired Parents↗
PubMed1994

Studies on long-lasting consequences of prenatal exposure to anticonvulsant drugs.

Based on neonatal examination at birth, it has been estimated that epileptic women have a 2-3 times greater risk of giving birth to an infant with congenital anomalies. But anticonvulsant drugs may also have more subtle influences on the developing foetus which are not visible at birth but only emerge later in life. Evidence for these functional teratogenic influences has been provided by animal research and follow-up studies in young children. This article discusses these findings in human and animal studies. In addition, the outline of a study carried out at the Department of Obstetrics and Neonatology, Academic Medical Centre, Amsterdam, is described. In this study cognitive functioning, fertility and gender role behaviour of young adults, who had been prenatally exposed to barbiturates and/or hydantoins was examined.

Abnormalities, Drug-Induced↗
PubMed1994

Substance use in pregnancy: do we care?

Two cohorts of substance-using women were compared retrospectively. From 1969 to 1979 a very high perinatal mortality rate (PMR 9.8%) was found among 92 polydrug-using women (1 twin excluded). Preterm delivery occurred in 25% of all pregnancies and in 30% of the children birth weight was below the 10th percentile. Nineteen women using heroin only had a worse fetal outcome (PMR 32%, preterm delivery in 47%, birth weight < 10th percentile in 42%). These results led to a strict surveillance system. In the period 1980-1989, 240 women (4 twins excluded) delivered after 16 weeks. Total fetal loss decreased to 2.1% and PMR to 0.4%, which was similar to results in controls. However, 22% of the women still delivered before 37 weeks and 27% delivered a child < 10th percentile. Methadone-using women were able to halve their dosage during pregnancy and 16 were detoxified. Multivariate analysis within the substance users of the second cohort showed that the neonatal abstinence syndrome, but not the (registered) amount of opiates used, was related to a lower birth weight. Not coping with prenatal care was related to a shorter pregnancy length. Multivariate analysis, including the controls, showed a significant relation of birth weight (345 g lower) with substance use. Also, head circumference was 0.8 cm smaller. Length of pregnancy however was related to smoking. This study shows that it is difficult to make substance users attend prenatal care, but also that women coping with prenatal care reduce substance intake. Opiate use might be responsible for lower birth weight, although not in a clear dose-response relationship, whereas lifestyle, as represented by not coping with prenatal care and the quantity of cigarette smoking, shortens the length of pregnancy.

Adult↗
PubMed1994

Macrophage-tropic variants initiate human immunodeficiency virus type 1 infection after sexual, parenteral, and vertical transmission.

Macrophage-tropic, non-syncytium-inducing, HIV-1 variants predominate in the asymptomatic phase of infection and may be responsible for establishing infection in an individual exposed to the mixture of HIV-1 variants. Here, genotypical and phenotypical characteristics of virus populations, present in sexual, parenteral, or vertical donor-recipient pairs, were studied. Sequence analysis of the V3 domain confirmed the presence of a homogeneous virus population in recently infected individuals. Biological HIV-1 clones were further characterized for syncytium inducing capacity on the MT2 cell line and for macrophage tropism as defined by the appearance of proviral DNA upon inoculation of monocyte-derived macrophages. Both sexual and parenteral transmission cases revealed a selective outgrowth in the recipient of the most macrophage-tropic variant(s) present in the donor. In three out of five vertical transmission cases, more than one highly macrophage-tropic virus variant was present in the child shortly after birth, suggestive of transmission of multiple variants. In three primary infection cases, homogeneous virus populations of macrophage-tropic, non-syncytium-inducing variants were present prior to seroconversion, thus excluding humoral immunity as the selective pressure in favour of macrophage-tropic variants. These observations may have important implications for vaccine development.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Preeclampsia is not associated with altered platelet vasopressin binding and cytosolic Ca++ concentration.

OBJECTIVES: Preeclampsia is an important cause of fetal and maternal morbidity and mortality. Recently it was described that platelet cytosolic Ca++ levels could be used to screen for preeclampsia. The current study investigated platelet arginine vasopressin receptor characteristics, platelet cytosolic Ca++ levels, plasma- and platelet-bound arginine vasopressin in white pregnant women. STUDY DESIGN: In a cross-sectional study nine third-trimester nulliparous pregnant women with gestational hypertension (seven with proteinuria, two with excessive weight gain without proteinuria) were compared with nine healthy nulliparous pregnant women matched for gestation length and age and 10 healthy age-matched nonpregnant women. Determined were (1) platelet arginine vasopressin receptor number and affinity, (2) platelet cytosolic Ca++ levels, both basal and on arginine vasopressin or thrombin stimulation, and (3) plasma- and platelet-bound arginine vasopressin levels. RESULTS: None of the measured parameters differed significantly among the three groups studied. Mean arginine vasopressin receptor number and affinity ranged from 108 to 143 receptors per platelet and 0.35 to 0.40 nmol/L, respectively. A single population of binding sites was found (Hill number 0.96). Basal Ca++ levels ranged from 113.4 to 133.3 nmol/L, on arginine vasopressin stimulation from 199 to 250 nmol/L. Median arginine vasopressin levels in platelet-poor plasma were between 1.2 and 2.4 pg/ml, with circulating platelets being estimated to possess two to five molecules of arginine vasopressin per platelet. A significant correlation was found between platelet cytosolic Ca++ levels before and after arginine vasopressin stimulation (r = 0.69, p < 0.001) and a weak correlation between platelet receptor density and arginine vasopressin-stimulated platelet cytosolic Ca++ levels (r = 0.38, p < 0.05). CONCLUSIONS: The studied parameters, platelet cytosolic Ca++ levels, whether basal or after stimulation with arginine vasopressin and vasopressin platelet receptor density and affinity, do not discriminate already hypertensive or preeclamptic white women from nondiseased subjects. A valuable test to screen for preeclampsia awaits further prospective studies.

Adult↗
PubMed1993

Genomic human immunodeficiency virus type 1 RNA variation in mother and child following intra-uterine virus transmission.

In order to study the relationship between virus populations in a human immunodeficiency virus type 1 (HIV-1)-infected mother and her infant, we analysed a 276 bp fragment, including the V3 region, of genomic HIV-1 RNA purified from serum. Samples were collected from the mother 6, 4 and 2 months prior to delivery, during delivery and 10 months after childbirth (samples MA to ME, respectively) and from the infant at birth (cord blood) and the ages of 6 weeks and 9 months. A heterogeneous sequence population was observed in the maternal samples (mean nucleotide variation of 2.4 to 4.2%, range 0 to 8.3%). Until the age of 6 weeks the sequence population in the infant was highly homogeneous (mean nucleotide variation < or = 0.7%, range 0 to 2.5%). At 9 months of age, the infant's virus population showed more heterogeneity (mean nucleotide variation of 1.8%, range 0.4 to 3.6%) and a drift in the consensus sequence was observed. The evolution of the V3 region in the mother was characterized by accumulation of amino acid substitutions diverging from the virus population observed in the infant. The mean nucleotide distance between the maternal sequence populations and the sequence population of the child at birth was 2.8, 2.6, 3.7, 5.2 and 5.3% for the samples MA, MB, MC, MD and ME, respectively. Nearly complete replacement at position 308, previously described as antigenically important, from a proline to a histidine was observed during pregnancy, whereas all clones of the child's virus at birth and at 6 weeks contained a proline at that position. In conclusion, intra-uterine transmission is associated with a homogeneous sequence population in the child at birth, which is more closely related to the sequence population present in the mother during the first and second trimester of pregnancy than to the sequence population at delivery.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[HIV infection in pregnant women in The Netherlands].

A review is given of the pregnant women with HIV infection known to the co-ordinating centre of the 'Dutch prospective study of HIV seropositive pregnant women and their children'. Fifty-five women with 57 pregnancies were discovered between 1 September 1985 and 1 January 1991. Of these women, 60% were not of Dutch origin and 56% were living in Amsterdam. Thirty-two women were (former) intravenous drug users. In 23 women heterosexual transmission was likely; two women were also blood transfusion recipients. Nearly half (11/23) of these women came from, or had a partner from, an AIDS-endemic area. In 16 women HIV seropositivity was known before pregnancy. Twenty-four women were specifically tested during pregnancy or within 1 week after parturition because of risk factors for HIV infection. Fifteen women were discovered in a HIV screening programme of pregnant women in Amsterdam (n = 13) and the University Hospital of Groningen (n = 2). At first, eight of these women did not mention risk factors. Thirty-five women could choose abortion (less than or equal to 20 weeks of gestation); the majority (69%) decided to continue pregnancy. Twelve pregnancies ended in an elective or spontaneous abortion, 39 in the birth of 40 children (one pair of twins) of whom 39 were viable, three women were still pregnant and of three the pregnancy outcome was unknown. Preterm delivery (8/39) and birth weight less than 2500 gram (7/39) were seen frequently, the latter particularly in women (formerly) using intravenous drugs (6/25).

Adult↗