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Biomedical subjects

F J Los

Publications and source records attributed to F J Los.

At least 73 records · Page 4Linked to original sources
PubMed1992

Maternal serum alpha-fetoprotein levels and fetal outcome in early second-trimester oligohydramnios.

Early second-trimester oligohydramnios was associated with normal maternal serum alpha-fetoprotein (MSAFP) levels in nine out of 26 cases (35 per cent). Congenital malformations of the fetal urinary tract resulting in fetal anuria were present in nine cases; in seven of them, normal MSAFP levels were measured. In contrast, normal MSAFP levels were established in only 2 out of the 17 cases without fetal malformations. These data suggest that fetal urine is the major source of elevated AFP in the maternal compartment in early second-trimester oligohydramnios. This is further supported by the lack of any relationship between concentrations of MSAFP non-reactive with Concanavalin A, originating mainly from the yolk sac-derived amniotic fluid AFP pool, and the presence of fetal diuresis. Three out of 26 women had experienced early second-trimester oligohydramnios in a previous pregnancy, suggesting the existence of a recurrence risk for this condition.

Concanavalin A↗
PubMed1992

Prenatal analyses in a pregnancy at risk for beta-mannosidosis.

Prenatal analyses were performed in the pregnancy of the mother of a patient with beta-mannosidase deficiency. Partial deficiency of beta-mannosidase activity in the chorionic villi indicated a heterozygous fetus and this first-trimester diagnosis was subsequently confirmed by amniocentesis.

Amniocentesis↗
PubMed1992

Prenatal diagnosis of spina bifida aperta after first-trimester valproate exposure.

In the context of a prospective study on the adverse effects of anti-epileptic drugs on fetal outcome, we evaluated our experience with prenatal diagnosis by ultrasonography and alpha-fetoprotein (AFP) determination in amniotic fluid. We compared these results with AFP values in maternal serum obtained prior to amniocentesis. From November 1985 to July 1990, amniocentesis at 16-18 weeks of gestation was performed in 267 pregnancies of 237 different women using anti-epileptic drugs. Among 92 pregnancies with maternal valproic acid use, five (including one concordantly affected monozygotic twin-pair) were terminated because of a spina bifida aperta, all prenatally diagnosed by AFP determination and acetylcholinesterase electrophoresis in amniotic fluid. The maternal serum AFP level was raised (> or = 2.5 multiples of the median (MOM) for singleton pregnancies and > or = 4.5 MOM for twin pregnancies) in only two of these five affected pregnancies. We emphasize that maternal serum AFP levels may be unreliable for prenatal screening for fetal neural tube defects in women taking valproate and recommend that amniocentesis and fetal ultrasound examination should be offered directly.

Acetylcholinesterase↗
PubMed1992

The disposition of valproate and its metabolites in the late first trimester and early second trimester of pregnancy in maternal serum, urine, and amniotic fluid: effect of dose, co-medication, and the presence of spina bifida.

We have studied 52 pregnancies in epileptic women taking long-term valproate and have measured the concentrations of the parent compound and 13 of its metabolites by gas chromatography-mass spectrometry in amniotic fluid, maternal serum, and 24 h maternal urine samples. All metabolites of valproate present in the serum could also be detected in the amniotic fluid, although at much lower concentrations. Amniotic fluid concentrations of valproate and several of its metabolites ((E) delta 2-valproate, (2E,3'E) delta 2,3'-valproate, and 3-keto-valproate) correlated with total valproate concentrations as well as with unbound valproate concentrations in maternal serum. We suggest that the amniotic fluid acts as a deep compartment, with slow appearance and disappearance of valproate and its main metabolites. The data further suggest that during the first and early second trimesters of pregnancy the beta-oxidation of valproate decreases. In pregnancies associated with fetal neural tube defects (n = 5) significantly higher daily doses of valproate were used compared with normal pregnancies (n = 47). This resulted in higher concentrations of valproate in maternal serum. However, the metabolite patterns in maternal serum, 24 h urine samples, and amniotic fluid did not show any significant differences in pregnancies with neural tube defects.

Amniocentesis↗
PubMed1992

The risk of spina bifida aperta after first-trimester exposure to valproate in a prenatal cohort.

Use of antiepileptic drugs (AEDs) during pregnancy is associated with an increased risk of congenital malformations. Spina bifida aperta has been linked specifically to valproic acid (VPA) (estimated risk, 1 to 2%). The actual risk, the exclusive association of VPA with spina bifida and not anencephaly, and the precise causative relation remain matters of discussion. A prospective cohort study of pregnant women with epilepsy receiving AEDs and referred for prenatal diagnosis before week 22 of gestation was conducted, with follow-up to 3 months after birth. Pregnancies (291 singleton and 6 twin) in 261 women were evaluated. The prevalence of anomalies after exposure to any AED was 6.9%. For fetuses exposed to VPA, the prevalence was 9.4%, including six cases of spina bifida, two of which were in monozygotic twins (giving a prevalence rate of 6.3%, or 5.4%, if twins counted as one). Spina bifida was associated with a significantly higher average daily dose of VPA as compared with pregnancies with normal outcome (1.640 +/- 136 mg/d vs 941 +/- 48 mg/d, p = 0.0001). No relation was observed between the occurrence of spina bifida and type of maternal seizure or epilepsy, family history of epilepsy or neural-tube defects, or medical history. From these results we suggest that when the use of VPA during pregnancy cannot be avoided, the teratogenic risk might be diminished by reduction of the daily dose.

Adult↗
PubMed1991

Acceptance of chorionic villus sampling in the southwest region of The Netherlands: a 5-year evaluation.

The acceptance of chorionic villus sampling (CVS) for monitoring pregnancies at risk for chromosomal and genetic disorders was studied from its introduction in the Centre for Clinical Genetics in Rotterdam in 1984 until 1988. Special attention was given to increasing acceptance in the group with advanced maternal age (AMA) (12.6% CVS in 1984, 52.2% CVS in 1988) and the group with a high genetic risk (HGR) (42.7% in 1984, 86.7% in 1988). The odds-growth-rate in CVS was 1.64 and 1.67 respectively, which was not significantly different. The relatively limited use of CVS at AMA is most likely determined by the fact that a considerable number of patients are referred too late in pregnancy to have the option of CVS.

Amniocentesis↗
PubMed1991

Transcervical (TC) and transabdominal (TA) CVS for prenatal diagnosis in Rotterdam: experience with 3611 cases.

Data from 3611 consecutive CVS (TC, N = 1780; TA, N = 1831) were analysed with emphasis put on influence of maternal and gestational age at CVS on the fetal loss rate less than 28 weeks. For TC-CVS the gestational age varied from 9.3-11.6 weeks, for TA-CVS from 9.3-20 weeks. Sampling efficacy at first attempt was 86.5 per cent and 95 per cent respectively. In 4.6 per cent an abnormal result was established. In older mothers (N = 2362) the fetal loss rate was significantly higher (p = less than 0.05) when sampled before 12 weeks (TC-CVS 6.2 per cent, TA-CVS 5.8 per cent). When the CVS (TA) was performed after 12 weeks the fetal loss rate decreased to 2.4 per cent. In 1079 younger women the fetal loss rate remained low (TC 2.8 per cent; TA less than 12 weeks 1.8 per cent; TA greater than 12 weeks 1.7 per cent) and was not influenced by gestational age at the time of sampling. We concluded both methods safe and reliable when the choice of application considers maternal age.

Abortion, Therapeutic↗
PubMed1990

Transabdominal chorionic villus sampling in a multiple pregnancy at risk of argininosuccinic aciduria: a case report.

We report on a 32-year-old G3P2 woman at increased risk of argininosuccinic aciduria in her offspring. In her first infant, the disease was diagnosed at age 3 months. In the second pregnancy, the disorder was excluded following incorporation of radio-labeled 14C-citrulline in intact chorionic villi obtained through transcervical chorionic villus sampling at 10 weeks gestation. Twins were diagnosed in the third pregnancy. Separate transabdominal chorionic villus sampling of both fetuses was carried out at 10 weeks gestation. Chromosome analysis demonstrated a normal male and female karyotype. Incorporation of radio-labeled 14C-citrulline in intact villi was deficient in both villus samples, establishing the diagnosis of argininosuccinic aciduria in both fetuses. The present results confirm the reliability of direct analysis of villi for the diagnosis of argininosuccinic aciduria.

Adult↗
PubMed1990

Interpretation of chromosome mosaicism and discrepancies in chorionic villi studies.

In 3,000 chorionic villi studies (CVS) 33 cases of mosaicism and 7 false-positive cell lines in all cells were seen. The mosaic cell lines were caused by aneuploidy of autosomes (13x), sex chromosomes (9x), and structural anomalies (11x). Mosaics of fetal origin were only 4 cases of trisomy 21 and one 47,XXY mosaic. In 7 cases abnormal karyotype of non-fetal origin was seen in all cells in direct studies, including trisomy 16 (3x) and trisomy 18 (2x). The combined use of direct CVS and cell cultures always uncovered the non-fetal origin of chromosome abnormalities and the study of cultured cells in all cases could have prevented 5 terminations. Complete follow-up studies demonstrated no false-negative results. Therefore, CVS can be nearly 100% accurate when both direct studies and cultures are examined in cases of mosaicism and other cell lines of possible non-fetal origin, such as trisomy 16, trisomy 18, translocation (21;21), and 45,X cells.

Aneuploidy↗
PubMed1990

Trisomy 21 mosaicism in gonads with unexpectedly high recurrence risks.

The recurrence risk for Down syndrome (DS) is about 1% in case of a previous offspring with trisomy 21 and minimal in case of a de novo (21;21) translocation. We have monitored 1,211 pregnancies in the first and second trimester after a prior occurrence of trisomy 21. Six couples had a trisomy 21 fetus in a subsequent pregnancy. We studied their lymphocytes, fibroblasts, and in one case ovaries, to detect parental mosaicism for chromosome 21. We detected mosaicism in 2 parents with 3 and 4 pregnancies, respectively, in which trisomy 21 was found. In one it was present in 47% of cells from the ovaries. Another couple with a pregnancy monitored because of a first child with a de novo (21;21) translocation had normal chromosomes themselves and one normal child, but 2 more pregnancies with a (21;21) translocation. It is concluded that thorough cytogenetic study of parents is indicated after 2 pregnancies with regular or translocation trisomy of chromosome 21. Genetic counseling should consider the possibility of an elevated recurrence risk due to gonadal mosaicism in one parent.

Adult↗
PubMed1990

Transabdominal villus sampling in early second trimester: a safe sampling method for women of advanced age.

Transabdominal chorionic villus sampling (TA-CVS) was performed in 707 viable singleton pregnancies to exclude chromosomal abnormalities. Maternal age ranged between 36 and 49 years (mean 37.9 years); gestational age varied between 10.2 and 18.3 weeks (mean 13.3 weeks). In 639 women (90.4 per cent), a sufficient amount of chorionic tissue (greater than or equal to 10 mg) was obtained after one needle insertion; in 66 women (9.3 per cent) two insertions were needed. An abnormal chromosome pattern was established in 19 cases (2.9 per cent). Vaginal bleeding or spotting within 28 days after TA-CVS occurred in 11 cases (1.5 per cent). The completed follow-up of 678 chromosomally normal pregnancies showed an overall fetal loss rate of 2.6 per cent before 28 weeks. The overall perinatal mortality was 0.9 per cent. When relating fetal loss to gestational age at TA-CVS, this was 6.6 per cent in women sampled before 12 weeks against only 1.8 per cent after 12 weeks. At the same time, the percentage of fetal loss occurring within 2 weeks following the procedure was 75 and 30 per cent, respectively. It is suggested that these data reflect the decline in spontaneous abortion rate during this particular period of pregnancy. It is concluded that TA-CVS is an effective procedure which, when performed after the natural decrease of fetal loss, appears to be a safe option for women of advanced maternal age.

Abdomen↗
PubMed1989

Prenatal diagnosis of cystic kidney disease with ventriculomegaly: a report of six cases in two related sibships.

In 2 consanguineous relationships, a Cape Verdian man fathered six fetuses (5 male) with fetal ventriculomegaly and echodense fetal kidneys as visualized by ultrasonography between 16 and 32 weeks. During prenatal monitoring, an increased alpha fetoprotein level and abnormal acetylcholinesterase were detected at amniocentesis in 5 of 6 affected fetuses. Chromosomes were normal. Five pregnancies resulted in elective termination; one child was still-born prematurely. Hydrocephalus and cystic disease of the (renal) cortico medullary areas were found. One fetus had polydactyly. The differential diagnosis and prenatal diagnosis of this presumably autosomal recessive syndrome are discussed.

Acetylcholinesterase↗
PubMed1989

Prenatal diagnosis of purine nucleoside phosphorylase deficiency in the first and second trimesters of pregnancy.

Prenatal diagnosis was performed in two successive pregnancies of a mother with a previous child with purine nucleoside phosphorylase (PNP) deficiency. In one pregnancy, an affected fetus was diagnosed in the 18th week of gestation after the demonstration of PNP deficiency in cultured amniotic fluid cells. Also an abnormal purine nucleoside profile was found in the amniotic fluid. The diagnosis of an affected fetus was confirmed by the analysis of cultured fetal skin fibroblasts and placental villi. The complete deficiency of PNP activity in placental villi confirms that the prenatal diagnosis of this disorder is possible by the direct investigation of chorionic villi. In the subsequent pregnancy, a heterozygous fetus was predicted in the tenth week of pregnancy by using chorionic villi.

Adenosine Deaminase↗
PubMed1989

Transabdominal chorionic villus sampling in the second trimester of pregnancy: feto-maternal transfusions in relation to pregnancy outcome.

Volumes of feto-maternal transfusions (FMTs) in transabdominal chorionic villus sampling (TACVS) in the second trimester of pregnancy were calculated from the difference between maternal alpha-fetoprotein (AFP) concentrations before and 1 h after TACVS. In 50 pregnancies, there existed no correlation between FMT volume and the amount of villi collected or the number of TACVS attempts. The expected risk of fetal exsanguination due to very voluminous FMT could not be substantiated. In one case, immunization could have been the cause of hydrops fetalis, although only a volume of 0.15 ml could be calculated.

Adult↗
PubMed1989

Evaluation of transcervical chorionic villus sampling with a completed follow-up of 1550 consecutive pregnancies.

Data from 1,550 consecutive pregnancies after first-trimester prenatal diagnosis by transcervical chorionic villus sampling (TC-CVS) are presented. The sampling efficacy was 97.8 per cent; the mean amount of collected villus tissue was 23 mg (range 5-100 mg). There were 97 affected fetuses, mainly (73.2 per cent) with a chromosomal abnormality or a male karyotype in carriers of X-linked disease. Pregnancy termination in these and four other women for social reasons resulted in 1449 continuing pregnancies. In these pregnancies, the fetal loss rate up to 28 weeks of gestation was 5.1 per cent with the highest loss rate (3.9 per cent) before 16 weeks. When relating this fetal loss rate to maternal age, this was 6.1 per cent in the advanced maternal age group (greater than or equal to 36 years) against 3.1 per cent in the younger age group. In 1,376 pregnancies continuing beyond 28 weeks, the perinatal mortality rate was 1.1 per cent; the percentage of non-genetic congenital anomalies was 0.9 per cent. The reproductive pattern of women at high genetic risk after CVS followed by pregnancy termination was evaluated. Within 12 months after the first CVS followed by pregnancy termination, 70 per cent of women again requested CVS in a subsequent pregnancy.

Abortion, Induced↗
PubMed1989

Chromosome analysis of small and large L5178Y mouse lymphoma cell colonies: comparison of trifluorothymidine-resistant and unselected cell colonies from mutagen-treated and control cultures.

Mutagenesis assays at the thymidine kinase (TK) locus in L5178Y mouse lymphoma cells frequently yield mutant colonies with a bimodal size distribution. The objectives of this study were to determine whether a relationship exists between mutant colony size and chromosomal aberrations and whether the colony-size distributions obtained from this assay can indicate the clastogenic activity of a test chemical. Cells from 8 different types of L5178Y mouse lymphoma cell colonies were examined for chromosomal abnormalities within 10 cell generations after colony isolation. The colonies included small (sigma) and large (lambda) unselected cell (UC) and trifluorothymidine-resistant (TFTr) colonies derived from TK +/- cell cultures treated with the solvent dimethyl sulfoxide (DMSO) or hycanthone methanesulfonate (HYC). Chromosome abnormalities were present in cells from 12% (7/60) of the UC colonies, but there was no apparent relationship between colony diameter and the presence of chromosomal abnormalities. Abnormalities affecting chromosome 11, which is believed to be the site of the TK gene, were not observed in cells from UC colonies. Abnormalities affecting chromosome 11 were observed only in cells from sigma-TFTr colonies irrespective of whether they were spontaneous (5/15 colonies) or induced by HYC (4/15 colonies). Overall, 30% (9/30) of sigma-TFTr colonies had cells with an abnormal chromosome 11 and 10% (3/30) had abnormalities affecting other chromosomes. Abnormalities affecting chromosome 11 were not observed in cells from lambda-TFTr colonies (0/30 colonies). The observation of only 30% of sigma-TFTr colonies with chromosome damage affecting chromosome 11 indicates that other mechanisms, in addition to chromosome damage at the level of resolution used in this study (i.e., 200-300 chromosome bands). contribute to small TFTr colony size.

Animals↗