Biomedical subjects

D A Sassoon

Publications and source records attributed to D A Sassoon.

24 records · Page 2Linked to original sources

PubMed1990

Perinatal outcome in triplet versus twin gestations.

The present study was conducted to determine whether triplet pregnancies are associated with a significantly worse perinatal outcome than twin pregnancies. Maternal and neonatal outcome was evaluated in 15 triplet and twin pregnancies that were matched for maternal age, race, type of medical insurance, delivery mode, parity, and history of previous preterm delivery. Preterm labor occurred significantly more often in triplet than in twin gestations (80 versus 40%), as did preterm delivery (87 versus 26.7%). Triplets had a significantly lower mean birth weight (1720 versus 2475 g) and gestational age at delivery (33 versus 36.6 weeks). In addition, 53.3% of triplet pregnancies but only 6.7% of twin pregnancies had one or more neonates with intrauterine growth retardation. Discordancy also occurred more frequently in triplets than in twins (66.7 versus 13.3%). The mean averaged neonatal hospital stay was significantly higher in triplets (29 versus 8.5 days), and triplets had a fivefold increased risk of requiring neonatal intensive care as compared with twins. However, there were no significant differences between the groups in maternal morbidity or major neonatal complications such as respiratory distress syndrome or intraventricular hemorrhage. We believe that these data will be useful in counseling patients with respect to the anticipated perinatal outcome of triplet pregnancies.

Adult↗

PubMed1990

The biophysical profile in labor.

To determine whether the biophysical profile would be a valuable intrapartum addition to fetal heart rate monitoring in predicting umbilical arterial acid-base status at delivery, 95 patients at term had serial studies during labor and umbilical artery blood gas analysis. There was no significant association between biophysical profile score and cord blood pH, nor was there a difference in scores between the acidemic and nonacidemic groups. Of the five components of the initial biophysical profile, only a nonreactive nonstress test (NST) was associated with both pH 7.20 or less (P = .019) and metabolic acidemia (P = .016). None of the individual variables of the final examination correlated with a pH of 7.20 or less. However, a nonreactive NST was associated with metabolic acidemia (P = .03), as was the presence of breathing (P = .03). Of the ten infants with pH 7.20 or less, eight had an initial and five had a final biophysical profile score of 8 or higher. Of the five whose pH was less than 7.15, four had an initial and three a final score of 8 or more. Finally, of the five with metabolic acidemia, four had an initial and two a final score of 8 or higher. Half of the acidemic fetuses had final biophysical profile scores of 8 or higher, suggesting that this score in labor is not reliable to rule out acidemia at delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1989

Myogenin, a factor regulating myogenesis, has a domain homologous to MyoD.

In this report, we describe the isolation, sequence, and initial characterization of the cDNA for the muscle-specific regulatory factor skeletal myogenin. Transfection of myogenin into the mesenchymal cell line C3H10T1/2 produces cells expressing muscle-specific markers. Myogenin is absent in undifferentiated cells, peaks, and then declines following a stimulus to differentiate, and is overexpressed in myoblasts selected with 5-bromodeoxyuridine for the overproduction of factors that regulate the decision to differentiate. High levels of myogenin transcripts are present in the myotomal region of somites at 8.5 days of gestation in the mouse. Although myogenin and MyoD are different genes, they share the myc homology domain. Myogenin and MyoD thus form part of a gene family regulating myogenesis, and together with myd may constitute a set of factors that interact to regulate the determination and differentiation of muscle cells.

Amino Acid Sequence↗

PubMed1989

Perinatal factors influencing atrial natriuretic peptide levels in umbilical arterial plasma at the time of delivery.

Little is known about atrial natriuretic peptide metabolism or secretion in the human fetus. The purpose of this study was to determine if both the placenta and umbilical vessels are possible sites of atrial natriuretic peptide metabolism and to evaluate the effects that labor, route of delivery, prolonged pregnancy, preeclampsia, and fetal distress have on umbilical arterial atrial natriuretic peptide levels. We found that plasma atrial natriuretic peptide levels in the umbilical artery are significantly greater than those in the vein (p less than 0.001). Umbilical arterial and umbilical venous atrial natriuretic peptide levels were higher in plasma samples collected immediately at delivery when compared with those obtained 10 minutes later (p less than 0.001). Umbilical arterial atrial natriuretic peptide levels were elevated in pregnancies complicated by preeclampsia and fetal distress (p less than 0.01). Labor, route of delivery, and prolonged pregnancy had no effect on umbilical arterial atrial natriuretic peptide levels. We propose that both the placenta and umbilical vessels contain atrial natriuretic peptide receptors that are involved in the clearance or metabolism of atrial natriuretic peptide. The increased umbilical arterial atrial natriuretic peptide levels present in preeclampsia and fetal distress may reflect an attempt by the fetus to regulate blood flow.

Atrial Natriuretic Factor↗

PubMed1988

Transcripts of alpha-cardiac and alpha-skeletal actins are early markers for myogenesis in the mouse embryo.

Among the first tissues to differentiate in the mammalian embryo are cardiac and subsequently skeletal striated muscle. We have developed specific cRNA probes corresponding to the 5' noncoding regions of alpha-cardiac and alpha-skeletal actin mRNAs in order to investigate myogenesis in the mouse embryo. Transcripts coding for cardiac actin which is the major isoform of the adult heart can first be detected between 7.5 and 7.8 days p.c. in the developing heart and are observed in all somites as they are formed. In addition, alpha-skeletal actin transcripts are accumulated at much lower levels in cardiac tissue and newly formed somites; both heart and skeletal muscle show co-expression of this actin gene pair at all stages of development examined. The fact that cardiac actin transcripts can be observed in the myotomal portion of the somite prior to muscle fibre differentiation indicates that cardiac actin transcripts (and to a lesser extent skeletal actin transcripts) are markers not only of striated muscle tissue, but also of earlier stages of the myogenic programme in vivo.

Actins↗

PubMed1987

Androgen regulation of muscle fiber type in the sexually dimorphic larynx of Xenopus laevis.

We used histochemical techniques [assays for adenine triphosphatase (ATPase) and succinate dehydrogenase (SDHase) activity] to identify muscle fiber types in the larynx of Xenopus laevis. Male muscle is made up of one fiber type, medium-sized fibers (approximately 9 microns2) that stain lightly for acid-stable ATPase and intensely for SDHase activity. In contrast, the female has 3 fiber types: small fibers (approximately 6 microns2) that stain intensely for ATPase and SDHase, medium-sized fibers (approximately 13 microns2) with moderate staining for ATPase and dark staining for SDHase, and large fibers (approximately 15 microns2) with little SDHase or ATPase activity. Long-term castration (6 months) has no effect on histochemical staining of adult male fibers. Long-term testosterone treatment (5 months) increases the proportion of medium-sized, moderately staining fibers in adult females, and reduces the proportion of both the small, darkly staining fibers and the large, lightly staining fibers. At metamorphosis, both males and females have 3 fiber types whose ATPase activity is similar to that of the adult female. However, no SDHase activity is observed. Treatment of juveniles for 3 weeks with testosterone results in nearly complete masculinization of muscle fibers, as judged by increased cross-sectional area, homogeneous ATPase staining, and a marked increase in SDHase activity. Thus, juvenile muscle is considerably more responsive to testosterone than is adult female muscle. We propose that the uniform metabolic properties of male laryngeal muscle contribute to the production of the rapid (66 Hz) mate call vocalizations characteristic of this species. Further, our results suggest that androgens direct the masculinization of laryngeal muscle fibers during postmetamorphic development.

Androgens↗