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Biomedical subjects

B L Tabor

Publications and source records attributed to B L Tabor.

8 recordsLinked to original sources
PubMed1992

Platelet-activating factor antagonists decrease lung protein leak in preterm ventilated rabbits.

OBJECTIVE: The preterm ventilated lung is characterized by an increased protein leak from the pulmonary vascular spaces into the air spaces, which interferes with lung function and plays a role in neonatal respiratory distress syndrome. To investigate the role of platelet-activating factor in this process, platelet-activating factor antagonists were given to preterm ventilated rabbits. STUDY DESIGN: New Zealand White rabbits were delivered on day 28 of 31 days' gestation. Each rabbit pup received saline solution or one of two platelet-activating factor antagonists and were ventilated for 30 minutes with measurement of compliance, surfactant pool size, and protein leak into and out of the lung. Statistical analysis was performed with analysis of variance followed by Student-Newman-Keuls correction for multiple comparisons. RESULTS: There were no differences in lung compliance, surfactant pool size, or protein leak out of the air spaces among any of the groups. Treatment with the platelet-activating factor antagonists decreased the protein leak into the air spaces by greater than 50% and into the lung as a whole by 40% (p less than 0.01). CONCLUSION: Platelet-activating factor plays a role in the protein leak seen in the preterm lung, which contributes to neonatal respiratory distress syndrome.

Animals↗
PubMed1992

Lung albumin recovery in surfactant-treated preterm ventilated lambs.

Preterm ventilated animals and infants with respiratory distress syndrome (RDS) develop proteinaceous alveolar edema. To study the effect of postnatal age on intravascular radiolabeled albumin accumulation into lungs, preterm lambs at 132 days gestational age were ventilated after treatment with sheep surfactant or cow surfactant extract for periods as long as 24 h. Lambs not treated with surfactant were studied for only 5 h because of severe respiratory failure. All lambs were given radiolabeled albumin by intravascular injection 1 h before they were killed, and the net recovery of the labeled albumin was measured in the lung tissue and air space as quantified by alveolar lavage. Net 1-h radiolabeled albumin recoveries in the lungs decreased from 5 to 6% soon after birth to 0.9% at 24 h in the surfactant-treated groups (p less than 0.01). At 3 h there was less labeled albumin recovery by alveolar lavages in lambs treated with sheep surfactant than in control lambs and lambs treated with cow surfactant extract (p less than 0.05). Protein in alveolar washes from lambs treated with cow surfactant extract exceeded that in lambs treated with sheep surfactant at 3 h (p less than 0.05), but protein recoveries had decreased to similar values by 24 h, indicating a net clearance of air-space protein. These studies demonstrate a sixfold decrease in net albumin accumulation from birth to 24 h of age despite continued ventilation and oxygen exposure of the premature lamb lungs.

Animals↗
PubMed1991

The effect of maternal cocaine use on the fetus: changes in antepartum fetal heart rate tracings.

Fetal heart rate tracings of pregnancies complicated by cocaine use were analyzed to evaluate the effects of subacute maternal cocaine use on the fetus. Nonstress tests were performed twice weekly on patients from the perinatal substance abuse clinic with screening of maternal urine samples for cocaine, amphetamines, phencyclidine, and opiates at the time of each examination. Nonstress tests performed when the urine toxicology screen was positive for cocaine alone (positive cocaine nonstress tests) were paired with those from the same patient but performed when the screen was negative (negative cocaine nonstress tests). The nonstress tests were analyzed with the Lyons scoring system, which evaluates the baseline heart rate, the oscillatory amplitude of the baseline, the oscillatory frequency, decelerations, and accelerations. Twenty pairs of nonstress tests from 20 patients were analyzed. The total score was higher on the negative cocaine nonstress test in 70% of the pairs and equal in the remaining 30% (p less than 0.001). Significant differences occurred in the oscillatory amplitude (p less than 0.001), frequency (p = 0.002), and acceleration scores (p = 0.03) but not the fetal heart rate baseline or the deceleration scores. The observed changes may reflect alterations in fetal central nervous system neurotransmitters and fetal state regulation, which may affect the developing central nervous system of cocaine-exposed fetuses and in turn play a role in the developmental and behavioral abnormalities observed in cocaine-exposed infants.

Cocaine↗
PubMed1991

Dose effects of antenatal corticosteroids for induction of lung maturation in preterm rabbits.

Dose-response effects of corticosteroids were investigated in the preterm rabbit. Pregnant rabbits were given two doses of 0.01, 0.03, or 0.1 mg of betamethasone per kilogram every 24 hours, beginning on day 25 of gestation. Saline solution was used in a comparison treatment group. Half of the newborn rabbits received supplemental surfactant therapy after delivery via cesarean section on day 27, and all were ventilated on a ventilator-plethysmograph system for 30 minutes. The 0.01 and 0.03 mg/kg regimens had no effect on birth weight or lung function. The 0.1 mg/kg regimen resulted in fetal growth retardation and improved ventilatory measurements, gas exchange, and decreased protein accumulation in the lung, without increasing surfactant pool size. The induction of lung maturation by corticosteroids has multiple targets in the developing lung and does not exhibit a linear dose response.

Animals↗
PubMed1990

Dose response of thyrotropin-releasing hormone on pulmonary maturation in corticosteroid-treated preterm rabbits.

The dose-response effect of thyrotropin-releasing hormone in enhancing pulmonary maturation was investigated with six dosing regimens. Pregnant does received thyrotropin-releasing hormone (5, 10, or 50 micrograms/kg every 12 hours for four doses or one dose of 20 micrograms/kg) in conjunction with betamethasone beginning on day 25 of gestation, with betamethasone alone or saline solution used as comparison treatment groups. Half of the newborn rabbits received supplemental surfactant therapy after delivery on day 27, and all were ventilated on a ventilator plethysmography system for 30 minutes. There were no differences among the four thyrotropin-releasing hormone doses in surfactant pool sizes, compliances, or proteins leak into or out of the air spaces. The groups that received multiple doses of thyrotropin-releasing hormone had significantly higher perinatal loss rates than the single-dose group. The lungs of the group treated with thyrotropin-releasing hormone plus steroid and the rabbits treated only with steroid were more compliant than the controls without surfactant therapy, and showed significant improvements in protein leak. The addition of thyrotropin-releasing hormone to betamethasone improved several of the protein leak measurements compared with use of betamethasone alone. These results question the necessity of multiple doses of thyrotropin-releasing hormone to induce pulmonary maturation, especially when the higher perinatal mortality and the theoretical long-term effects of fetal hyperthyroidism on thyroid axis function are considered.

Animals↗
PubMed1990

Effects of surfactant protein-A on surfactant function in preterm ventilated rabbits.

Surfactant protein-A (SP-A) isolated from cow surfactant was added to organic solvent extracts of natural bovine surfactant or of Survanta (Abbott Laboratories), and dynamic compliances and pressure-volume curves were measured in rabbits with a gestational age of 27 days. Organic solvent extracts of natural surfactant and Survanta significantly improved dynamic compliances and lung volumes compared with those in control rabbits, but the effects were less than for natural surfactant. Adding 1 to 10% by weight SP-A to organic solvent extracts of natural surfactant increased dynamic compliances and maximal lung volumes on pressure-volume curves to values comparable with natural surfactant. Lung volumes at 10 cm H2O on deflation curves increased in a dose-dependent fashion at concentrations of SP-A between 0.5 and 5% by weight with no further improvement at 10% SP-A, although the volumes were significantly lower than for natural surfactant. Five percent by weight SP-A did not improve any measurements for Survanta. These results indicated that SP-A favorably improved organic solvent extracted natural surfactant function in vivo. However, the responses could not be generalized to another surfactant.

Animals↗
PubMed1990

Perinatal outcome associated with PCP versus cocaine use.

Phencyclidine (PCP) remains a widely used illicit drug, especially among adolescents and young adults. The pharmacologic effects of PCP are similar to those of cocaine; therefore, in this retrospective study 37 PCP-intoxicated parturients were matched for ethnicity, tobacco use, age, gravidity, and degree of prenatal care with 37 cocaine-intoxicated parturients. Infants exposed to PCP in utero, like those exposed to cocaine, had a high incidence of intrauterine growth retardation (32 vs 19%, N.S.), precipitate labor (43 vs 27%, N.S.), symptoms of neonatal drug withdrawal/intoxication, and prolonged neonatal hospitalizations. Moreover, they were more likely to have meconium-stained amniotic fluid (30 vs 19%, p = .05) and less likely to be born prematurely as cocaine-exposed infants. The comparison between the long-term developmental outcome of these groups awaits further study.

Adult↗