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Biomedical subjects

K J Blakemore

Publications and source records attributed to K J Blakemore.

At least 55 records · Page 3Linked to original sources
PubMed1990

Chorioangioma: a new inclusion in the prospective and retrospective evaluation of elevated maternal serum alpha-fetoprotein.

Two cases are presented which illustrate the association of elevated maternal serum alpha fetoprotein (MSAFP) levels and chorioangiomas. These cases emphasize the importance of ultrasound study of the placenta in MSAFP elevation evaluation. In addition, placentas from pregnancies with otherwise unexplained MSAFP elevations should be submitted for pathologic study. A definitive retrospective diagnosis may thus be provided.

Adult↗
PubMed1990

A comparison of the effect of epidural, general, and no anesthesia on funic acid-base values by stage of labor and type of delivery.

The effect of epidural anesthesia on neonatal acid-base status, before, during, and after labor, was determined by review of funic blood-gas values from 142 women with normal term pregnancies and normal fetal heart rate patterns. Funic acid-base parameters were compared by type of anesthesia when stratified by mode of delivery (vaginal, cesarean section in the active phase of labor, or elective cesarean section). Use of epidural analgesia for vaginal delivery was associated with significantly longer labor, lower umbilical arterial pH, higher arterial PCO2 and arterial bicarbonate values. In women who had cesarean section in the active phase of labor, use of epidural anesthesia was associated with significantly lower arterial and venous PO2 values when compared with women who received general anesthesia. Patients who had elective cesarean section with epidural anesthesia had funic acid-base values similar to women who had general anesthesia. Epidural analgesia-anesthesia offers no clear advantage to the uncompromised term fetus.

Acid-Base Equilibrium↗
PubMed1990

The effects of early treatment of hereditary tyrosinemia type I in infancy by orthotopic liver transplantation.

Two infants with hereditary tyrosinemia secondary to fumarylacetoacetate hydrolase (FAH) deficiency underwent orthotopic liver transplantation at 14 and 16 weeks of age due to poor clinical and biochemical response to medical therapy. Prompt clearance of abnormal metabolites with improved mental alertness and appetite occurred with minimal perioperative complications. Both infants tolerated rapid institution of normal diets and have shown progressive growth and development in the first 36 months after transplantation. Early liver transplantation should be considered as an option for infants with certain inherited metabolic disorders with poor prognosis, such as tyrosinemia type I, who fail to respond to medical therapy.

Amino Acid Metabolism, Inborn Errors↗
PubMed1990

Evaluation of elevations in maternal serum alpha-fetoprotein: a review.

Maternal serum AFP screening has had significant clinical impact on reducing unrecognized anencephaly and open neural tube defects at delivery. In addition, a growing number of other associations with maternal serum AFP elevations have become apparent since antepartum screening has become commonplace. We present in this review a clinically oriented approach to understanding the physiologic basis of maternal serum AFP elevations, both true- and false-positives. Compartmentalization of etiology, fetal and maternal, and routes of communication, amniotic fluid and placenta, allows a more logical approach to developing a differential diagnosis in this group of patients. In evaluating an elevation in maternal serum AFP, it is first necessary to consider the amount of fetal production by confirming the gestational age of the fetus and the number of fetuses present. Adjustments for maternal factors (weight, race, diabetes) must also be made. Fetal developmental defects which may lead primarily to leakage of the fetal proteins into the surrounding amniotic fluid with secondary elevations of maternal serum AFP enter into the differential diagnosis. The placenta itself is probably not a production source of AFP, but when the placenta is abnormal, a greater amount of AFP may be transported to the maternal circulation. Although our thoughts frequently do turn first to an increased maternal serum AFP reflecting an increased AFP concentration in the amniotic cavity with greater transference "across the membranes," in fact a far more common etiology is an increased transfer from the fetal circulation to the maternal via the fetal-maternal interface within the placenta. This is supported by the simple fact that the vast majority of maternal serum AFP elevations are not associated with amniotic fluid AFP elevations; the amniotic fluid AFP concentrations are usually normal. Thus, in circumstances where the fetal anatomy is grossly normal and there is not another explanation for elevations in maternal serum AFP, the placenta, either secondary to providing increased areas of transport or in providing an abnormal endothelial barrier, allows for greater transfer of fetal serum, and thus AFP, into the maternal compartment. An abnormal placenta is also a likely explanation for the increased risk of adverse pregnancy outcome that is associated with increased maternal serum AFP elevations for which no obvious etiology is found. The case herein reported suggests that an abnormal placenta which provides an altered interface for AFP flow between the fetal and maternal circulations may in fact be the etiology of the significant elevations of maternal serum AFP seen in cases of triploidy.(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Multiple↗
PubMed1990

Evidence for involvement of a Robertsonian translocation 13 chromosome in formation of a ring chromosome 13.

We have used molecular and cytogenetic methods to study the derivation of a ring chromosome 13 in the fetus of a woman mosaic for a translocation chromosome 13. DNA analysis showed that the translocation chromosome was a Robertsonian translocation, not an isochromosome. We suggest that the ring is derived from the translocation chromosome by breaks in both long arms and subsequent reunion, r(13) (q12q14).

Abnormalities, Multiple↗
PubMed1990

A prospective comparison of hourly and quarter-hourly oxytocin dose increase intervals for the induction of labor at term.

Fifty-two women undergoing labor induction and vaginal delivery at term were randomized between two oxytocin infusion protocols, involving hourly versus quarter-hourly increases in dose. Potential differences were sought of duration of labor, amount of uterine activity generated, and amount of oxytocin required. Starting at 0.5 mU/minute, oxytocin infusion was increased regularly in small increments every hour or every 15 minutes, according to group assignment. No differences were observed in potentially confounding clinical and demographic factors between the groups, including time to ruptured membranes. There were no clinically or statistically significant differences found for the duration of any phase or stage of labor, quantitative assessment of uterine activity, incidence of hyperstimulation, or neonatal outcome. The average dose of oxytocin used was lower in the hourly than in the quarter-hourly, protocol (4.4 versus 6.7 mU/minute; P less than .005). Significantly fewer patients on the hourly protocol required a maximum infusion rate exceeding 8 mU/minute (P less than .05). More patients on the hourly protocol either had oxytocin discontinued completely or were maintained at 4 mU/minute or less during the active phase of labor (P less than .05 and P less than .001, respectively). We conclude that a slower rate of increase in oxytocin administration via continuous infusion results in no prolongation of any phase of induced labor, while permitting lower infusion rates of the drug.

Drug Administration Schedule↗
PubMed1989

Antenatal detection of cystic hygroma.

Ultrasonographic evaluation, as a routine component of prenatal care, has significantly contributed to in utero assessment of pregnancy status. The detection of fetal abnormalities by ultrasound, however, has raised clinical questions and created parental dilemmas concerning the outcomes of such pregnancies. A relatively frequent anomaly observed on routine ultrasonographic examination is the posterior nuchal cystic hygroma. We report the prenatal detection of 16 cases of cystic hygromata and an analysis of a survey of the world's literature including an additional 155 cases. The information available from these 171 cases allows a clearer picture of the prognosis for fetuses in whom posterior cystic hygroma is detected in utero. Regarding outcome, 73.2 per cent of cases were terminated at the parents' request; 37 cases (22.6 per cent) resulted in fetal death in utero prior to any intervention. Only 7 per cent of continuing pregnancies resulted in live-born infants. Of the 142 cases with available cytogenetic findings, 22 per cent had normal karyotypes; 58 per cent had a karyotype associated with Turner syndrome phenotype; while autosomal trisomies and various structural abnormalities made up the remaining 20 per cent. Even among those fetuses with normal chromosomes, various physical anomalies were detected. Fetal hydrops was present in 66 per cent of the 102 cases with pertinent information. For those fetuses demonstrating cystic hygroma and normal karyotypes, Mendelian syndromes must be considered in the differential diagnosis. Alpha-fetoprotein evaluation of both maternal serum and amniotic fluid was not helpful in determining prognosis of these fetuses. The ultrasonographic finding of a posterior nuchal cystic hygroma, with or without accompanying fetal hydrops, is a valid indicator for a poor outcome of such pregnancies.

Adult↗
PubMed1988

Prenatal diagnosis by chorionic villus sampling.

The future of chorionic villus sampling can only be envisioned in the light of current knowledge. Amniocentesis will undoubtedly continue to hold an important place in prenatal diagnosis and has recently assumed greater importance in diagnosing neural tube defects and Down syndrome through widespread maternal serum alpha-fetoprotein screening. Patients now have a choice in prenatal diagnostic procedures for most genetic disorders. Many are already choosing chorionic villus sampling despite the questions that remain regarding risks and diagnostic accuracy. Risk figures for miscarriages due to the procedure and for intrauterine infection are especially needed. The issues of maternal contamination in laboratory analyses and chromosomal mosaicism that may not be present in the fetus are also of prime importance. Collaborative efforts continue to answer these and other questions so that in the future patients will be better able to make informed decisions regarding prenatal diagnosis.

Abortion, Spontaneous↗
PubMed1988

Oxytocin for the induction of labor.

The obstetric benefits and dangers of using oxytocin to promote uterine activity have long been appreciated. The induction of labor should be undertaken when the positive reasons for delivery outweigh the risks of allowing the pregnancy to continue. Over the years, recognition of the pharmacokinetics of oxytocin has led to modifications in how it is administered for the induction of labor. Most would agree that it should be used in the lowest possible dose that will provide a safe as well as efficacious process of labor for both patients: the woman and her fetus. The sensitivity of the uterus to oxytocin varies with gestational age and from individual to individual. Likewise, each fetus exhibits its own tolerance to the effects of this drug. Close surveillance of each patient's uterine activity response and labor curve and of her fetus's heart rate response is an essential part of the induction of labor.

Female↗
PubMed1988

Fetal vibro-acoustic stimulation: magnitude and duration of fetal heart rate accelerations as a marker of fetal health.

The relationship between intrapartum fetal acid-base status and fetal heart rate (FHR) response to vibro-acoustic stimulation was investigated in 100 patients. Fetal heart rate responses were classified into three groups: acceleration of 15 or more beats per minute lasting 15 or more seconds, acceleration of ten or more beats per minute lasting 10 seconds but less than 15 beats per minute and 15 seconds, or no acceleration. The mean fetal scalp blood pH was 7.29 in both groups with acceleratory responses, and such responses were highly predictive (98-100%) of scalp pH 7.20 or above. The mean pH value for the no-acceleration group (7.22) was significantly lower than the mean pH value for both groups with an acceleratory response (P less than .05), and the lack of response to the stimulus detected 90-100% of fetuses with a pH below 7.20. This sensitivity was reduced to 45% in the detection of fetuses with pH less than 7.25.

Acid-Base Equilibrium↗
PubMed1986

Chromosome deletion 1q42-43.

We report on a newborn male and a female of 3 years 9 months with de novo 1q42 or 43-qter deletions. These cases are compared with ten other reported cases.

Child, Preschool↗
PubMed1986

Rise in maternal serum alpha-fetoprotein concentration after chorionic villus sampling and the possibility of isoimmunization.

Maternal serum alpha-fetoprotein concentrations were determined by radioimmunoassay in 72 patients immediately before and after chorionic villus sampling for prenatal diagnosis. Fifty percent showed a rise of greater than or equal to 5 ng/ml. Assuming such rises represent fetal blood crossing the intervillous space, in 14% of the cases greater than or equal to 60 microliters of fetal blood was transferred at the time of chorionic villus sampling. A positive correlation was found between the magnitude of rise in maternal serum alpha-fetoprotein levels and the amount of villi removed (r = 0.39, p less than 0.001). When cases were examined by number of passes, a greater rise in maternal serum alpha-fetoprotein levels was noted with multiple passes than with single passes for a given sample size. The transfer of greater than or equal to 60 microliters of fetal blood suggests that maternal sensitization to fetal antigens may occur after chorionic villus sampling. During biopsy, as small a sample of villi as necessary for diagnosis should be taken with as few catheter passes as possible.

Biopsy↗
PubMed1986

Demonstration of myc and ras oncogene expression by hybridization in situ in hydatidiform mole and in the BeWo choriocarcinoma cell line.

With the use of hybridization in situ, c-myc and c-ras oncogene expression has been identified in the cytotrophoblast of hydatidiform mole and in the malignant trophoblast cell line BeWo. Expression was also found in early villous placenta. No expression of these two oncogenes was found in the cytotrophoblast of an 11-week conceptus, nor was it found in term placenta. The significance of these findings is discussed.

Cell Line↗
PubMed1984

First-trimester prenatal diagnosis of Tay-Sachs disease.

The prenatal diagnosis of Tay-Sachs disease was made in two at-risk fetuses by the analysis of chorionic villi obtained at 9 and 11 menstrual weeks, respectively. The diagnoses were based on the absence of beta-hexosaminidase A activity as determined by: (1) specific enzyme assays, (2) anion-exchange chromatography, and (3) cellulose acetate gel electrophoresis. The enzymatic diagnoses were confirmed on fetal tissue as well as by ultrastructural demonstration of the first-trimester fetal neuropathology. Optimal assay conditions for beta-hexosaminidase A in chorionic villi were established for the prenatal diagnosis of Tay-Sachs disease. Importantly, it was noted that a small amount of decidua or maternal blood could lead to misdiagnosis. Thus, extreme care must be taken in the preparation of chorionic villi for Tay-Sachs as well as other prenatal metabolic diagnoses.

Brain↗
PubMed1984

DNA analysis of first-trimester chorionic villous biopsies: test for maternal contamination.

We investigated the reliability of chorionic villous biopsy as a method to obtain tissues reflecting the genetic constitution of the embryo. In 12 pregnancies before elective termination, we searched for detectable maternal tissue after careful dissection of villi from small 2-5-mg specimens that yielded 7 micrograms of DNA per mg tissue. In Southern blotting experiments (1-2 micrograms DNA per lane), restriction fragment length polymorphisms (RFLPs) at an autosomal (D14S1) and a sex chromosomal (DXYS1) locus allowed recognition of maternally and embryonically derived alleles. Pure villi were obtained in six of the seven informative cases. One biopsy was not dissected satisfactorily; a mixture of embryonic and maternal DNA was found. Nonvillous tissues were mostly maternally derived in eight informative cases. Sex determination by molecular analysis (alleles at the DXYS1 locus) agreed with the karyotypes of uncultured or cultured villi. In one continuing pregnancy, distinct RFLPs indicated maternal inheritance of the alpha-thalassemia 1 trait in a female embryo without detectable maternal contamination. Reliable prenatal diagnosis depends on the specimen's purity. Maternal contamination can be evaluated by DNA analyses.

Biopsy, Needle↗
PubMed1984

A method of processing first-trimester chorionic villous biopsies for cytogenetic analysis.

Chorionic villous biopsy is emerging as a technique for obtaining fetal cells for prenatal diagnosis in the first trimester of pregnancy. Chromosome analysis has been performed on small villous biopsies using either direct harvests of uncultured cells or after culturing villous tissue. Here, we describe a method where both techniques can be used simultaneously; from a single villous biopsy, GTG-banded chromosomes of improved morphology are obtained from direct preparations and from cultured villous cells.

Biopsy, Needle↗