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Biomedical subjects

J W Johnson

Publications and source records attributed to J W Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1981

Betamethasone and the rhesus fetus: effect on lung morphometry and connective tissue.

Pregnant rhesus monkeys (Macaca mulatta) at 67 to 85% of term pregnancy were treated with betamethasone for 3 days and then delivered by cesarean section. These treated fetuses had larger lung volumes (32.6 +/- 1.8 ml/kg of body weight) compared to gestational age-matched controls (22.9 +/- 3.2 ml/kg of body weight; P less than 0.025) but no alterations in surfactant properties as measured by amniotic fluid L/S ratios, alveolar deflation stability, or lung phosphatidylcholine. These findings suggest that betamethasone effects an increase in fetal lung volume by some method other than alteration in alveolar surfactant concentrations. Results also demonstrated an 11% increase in the collagen to elastin concentration in the treated fetuses as compared to the control animals (P less than 0.01), suggesting alterations in lung connective tissue. Morphometric studies done on the air-fixed inflated lung demonstrated a decrease in the number of alveoli per unit volume of lung among the treated animals (0.95 +/- 0.07 x 10(6)) compared to the control animals (1.19 +/- 0.08 x 10(6); P less than 0.025) and a reduction in the mean surface area of the lungs of the treated animals (506 +/- 10 cm2 per cm3) compared to the control animals (561 +/- 9 cm2 per cm3; P less than 0.005). These findings suggest that at least part of the increased maximal lung volumes is related to increased alveolar distensibility. Together, these pressure volume findings, biochemical studies, and morphometric analyses indicate that a major effect of betamethasone on the rhesus fetal lung is to alter lung connective tissue characteristics. Alterations in lung surfactant appear to be of less functional significance in this rhesus fetal model. The disparity between these findings and other animal studies might be due to differences in species, the preparation, or the method of glucocorticoid administration.

Animals↗
PubMed1981

Sarcoma complicating von Recklinghausen disease in pregnancy.

Several cases of benign enlargment of neurofibromata during pregnancy are reported in the literature. We believe the present case to be the first report of malignant schwannoma occurring in such a tumor during pregnancy. As this case illustrates, malignant sarcomatous change must be carefully considered in such patients. Prompt diagnosis and radical therapy offer the only chance of survival in malignant schwannoma.

Abdominal Neoplasms↗
PubMed1981

Premature rupture of membranes and preterm labor: neonatal infection and perinatal mortality risks.

The purpose of this study was to analyze neonatal infection rates and perinatal mortality in births complicated by premature rupture of membranes (PROM) and spontaneous labor before term (less than 37 weeks' gestation). Neonatal infection occurred more commonly in preterm compared with term infants. The risk of infection due solely to PROM was insignificant compared with the risk attributable to preterm birth. Perinatal mortality and cause-specific mortality varied inversely with gestational age. These rates were not significantly different between groups with or without PROM or with or without associated development of maternal endometritis. Although the mortality due to infection was higher in preterm compared with term groups, most preterm deaths were attributed to other factors, particularly anoxia and respiratory causes. The diverse fetal risks associated with PROM and the associated maternal infection risks analyzed support expectant management when PROM occurs preterm.

Endometritis↗
PubMed1981

Premature rupture of the membranes and prolonged latency.

The aim of this retrospective study in 8320 patients with premature rupture of the membranes (PROM) was to determine the consequences of prolongation of the latent period. Among patients with pregnancies of more than 37 weeks' duration, those with PROM and latent periods of more than 1 day demonstrated an increased incidence of intrapartum fever (IPF), whereas those with latent periods of more than 3 days demonstrated a marked increase in fetal (but not neonatal) deaths. Although IPF and perinatal mortality were more common in preterm pregnancies, neither was found to increase or decrease with prolonged latency, provided differences in gestational ages and race were taken into account. In the absence of chorioamnionitis, there appears to be no benefit to delivery before 37 weeks' gestation.

Birth Weight↗
PubMed1981

Evaluation of a killed phase I Coxiella burnetii vaccine in cynomolgus monkeys (Macaca fascicularis).

The protective efficacy of a killed, purified, phase I Coxiella burnetii vaccine was tested in cynomolgus monkeys. Monkeys vaccinated once with 30 micrograms of the antigen were challenged 6 or 12 months later with virulent phase I rickettsiae administered in small-particle aerosols. The vaccine provided only partial protection, since some of the challenged monkeys developed clinical signs of illness. However, the vaccinated animals did not develop pneumonia as determined by radiographic evaluation nor any hematologic or chemical changes except for an increase in fibrinogen. Although rickettsiae were isolated from peripheral blood in vaccinated monkeys, the rickettsemia persisted for only 1-2 days; whereas, organisms were recovered from unvaccinated animals for 6-7 days. All vaccinated animals had circulating microagglutinating antibodies to phase I and phase II antigens 6 and 12 months after vaccination.

Animals↗
PubMed1981

Plasma prostaglandin in pregnant women with term and preterm deliveries.

Because of the involvement of prostaglandins in the labor mechanism, it was hypothesized that elevated prostaglandin levels would presage preterm deliveries. A comparison of plasma 13,14-dihydro-15-ketoprostaglandin F2 alpha (PGFM) levels was made between pregnant patients who eventually delivered at term (N = 22) and those who delivered preterm (N = 17). Maternal blood was collected from each patient at approximately 1-week intervals between 16 and 40 weeks' gestation and during labor. Mixed cord blood was also obtained at delivery. PGFM was measured in plasma by radioimmunoassay. Plasma PGFM concentrations did not vary throughout pregnancy. PGFM concentrations did increase during labor, and the highest levels were found in cord blood at delivery. Mean PGFM levels during labor and in cord blood were not significantly different between the preterm and term groups. In 1 preterm delivery patient the PGFM concentration during labor was higher than that of all other patients, including those who delivered at term. Excluding this patient, preterm labor PGFM concentrations were significantly lower (P less than .05) than those at term. In general, the study provides evidence that most cases of preterm labor are not characterized by elevated prostaglandin levels.

Adult↗
PubMed1980

A resilient trnasparent custom maxillofacial surgical dressing.

A new modality in postsurgical wound care to improve the quality of life in the extraoral maxillofacial surgical oncology patient has been described. This approach to protecting wounds of the face has the potential of being used for almost any external part of the body. The dressing has the advantages of sterility, durability, transparency, versatility, conformability, resiliency, comfort, protection, and economy. Maxillofacial surgeons can utilize the many positive advantages of this new type of dressing which is available through the maxillofacial prosthodontist.

Bandages↗
PubMed1980

Maternal administration of glucocorticoids.

No definite comment can be made, at this time, with respect to the safety of glucocorticoid therapy in the human fetus and newborn. Obstetricians and pediatricians need to be aware of the potential risks. Whether the fetal changes that have been reported thus far are permanent and whether they will have any postnatal functional significance are questions of major importance. Probably the greatest risk associated with antenatal steroid therapy is the potential abuse of this treatment. Longer treatment periods or higher doses of steroids will increase the risk for potentially adverse side effects. The recently stated opinion of Taeusch et al seems appropriate: "We conclude that steroids are effective in reducing risk of RDS, but safer and more efficacious approaches for the prevention of RDS should be sought" (91). Further studies are needed to determine the mechanisms of action of glucocorticoids and their risk/benefit ratios in regard to fetal and neonatal well being.

Animals↗
PubMed1980

Fetal tachycardia associated with intrauterine fetal thyrotoxicosis.

Tachycardia in both fetuses of a twin gestation was documented in a mother who had undergone subtotal thyroidectomy 8 years prior to her present pregnancy. Maternal and fetal plasma concentrations of long-acting thyroid stimulator (LATS) and amniotic fluid 3,3',5'-triiodothyronine (reverse T3) were determined. All values were consistent with the diagnosis of fetal thyrotoxicosis, as were cord blood studies performed on the fetuses post partum. Significant concentrations of LATS were present in fetal cord blood. The first fetus survived but suffered hyperthyroidism during the first 3 neonatal weeks. The second twin died, possibly of fetal thyrotoxicosis. These studies suggest that in women with a history of thyrotoxicosis, high levels of maternal LATS may in some instances provoke fetal thyrotoxicosis, which can be diagnosed by the measurement of amniotic fluid reverse T3.

Adult↗
PubMed1980

Asthma in pregnancy: current concepts.

Asthma complicates pregnancy with the same frequency as cardiac disease (1%) does. Although the incidence of severe asthma during pregnancy is low, its effect on the mother and fetus can be disastrous. Recent advances have improved the management of this problem. Representative cases and a review of asthma treatment in pregnancy are presented.

Acute Disease↗
PubMed1979

The relative significance of human placental lactogen in the diagnosis of retarded fetal growth.

The purpose of this prospective study was to determine whether serial maternal venous hPL determinations could identify pregnancies resulting in growth-retarded infants from a selected population at presumed high risk for IUGR. Our results demonstrated that mean hPL levels in IUGR outcome pregnancies were significantly lower than normal after 33 weeks' gestation. Mean hPL was also lower in some pregnancies resulting in normal-weight neonates with abnormally low PI or short CHL, suggesting that these neonates, despite normal birth weight achievement, may represent previously unsuspected.

Birth Weight↗
PubMed1979

Betamethasone and the rhesus fetus: multisystemic effects.

In this controlled study of betamethasone administration to pregnant rhesus monkeys, using dosages per gram of fetal body weight similar to those reported in several human clinical studies, the most significant fetal pulmonary changes observed were increases in maximum lung volumes. The fact that comparable increases in peak volumes were demonstrated on saline filling supports our contention that these changes are related primarily to lung structural alterations rather than surfactant effects. Additional findings in the treated animals included reduced fetal head circumference, thymus weight, adrenal weight, placental weight, and maternal postoperative weight and increased fetal hepatic weight. Any of these glucocorticoid-induced changes could portend serious side effects. Further studies are needed to delineate the risk:benefit ratio of such treatment.

Adrenal Glands↗