Search PubMed⌕ Search

Biomedical subjects

J Egberts

Publications and source records attributed to J Egberts.

69 records · Page 4Linked to original sources
PubMed1984

Intrauterine hypercarbia and lamb lung surfactant synthesis.

Prenatal asphyxia resulting in hypoxia, hypercarbia and amniotic fluid aspiration reduces the synthesis of the pulmonary surfactant. Using 135-day fetal lambs we studied the in utero effects of hypercarbic acidosis alone on fetal breathing activity, excised lung pressure-volume relationships and lamellar body (LB) surfactant disaturated phosphatidylcholine (DSPC) pool size and specific activity for [14C]palmitate. Fetal PaCO2 levels greater than 125 mm Hg for 30 min were associated with pH values less than 7.0 and very vigorous breathing activity. Analysis 22 h after the period of hypercarbic acidosis demonstrated no differences in pressure-volume relationships or the quantity of lamellar body surfactant DSPC. The specific activity of lamellar body DSPC also was not different although total label (dpm) per gram dry weight was higher and label was detected in the lavage fluid earlier in the acidotic lambs than controls. We conclude from these data that hypercarbic acidosis does not influence the synthesis or function of the pulmonary surfactant as assessed in this system. From these results and prior work from our laboratory we can infer that hypoxia remains the most probable cause for reduced surfactant synthesis in the asphyxiated fetus.

Acidosis, Respiratory↗
PubMed1984

Fluorescence polarization in gastric aspirate and in amniotic fluid and its relationship to the respiratory distress syndrome.

Fluorescence polarization of diphenylhexatriene (DPH), added to amniotic fluid can be used to estimate fetal lung maturity. In this study we estimated the fluorescence polarization (FP) value of gastric aspirates of newborns and of amniotic fluids and studied the relationship between the FP value and neonatal lung function. Gastric aspirates of 51 newborns and amniotic fluids of 13 cases were mixed with a DPH-phosphate buffered saline solution and incubated for 30 minutes at 37 degrees C. Fluorescence polarization was measured at 22 degrees C. The FP values of amniotic fluid are in accordance with results previously found. A highly significant negative correlation was present between the FP value in amniotic fluid and gestational age. The highest FP values were found in amniotic fluids of infants in whom respiratory distress developed. The FP values of gastric aspirates decreased also with gestational age. A rather poor negative correlation, however, was found between these FP values and gestational age. We also noticed that, before the 36th week of gestation, the FP values in gastric aspirates tend to be lower than those in amniotic fluids. Both high and low FP values were estimated in gastric aspirates of infants with RDS and of infants without respiratory problems. These results show that the measurement of the FP value in gastric aspirates of newborns is not an useful method to determine whether the infant will develop RDS or not.

Amniotic Fluid↗
PubMed1983

Fluorometric procedure for determining "lamellar body" phospholipids in the particulate fraction of amniotic fluid after filtration.

A rapid (30-min) semiautomated continuous-flow procedure is described for use in assessing the phospholipids of the particulate ("lamellar body") fraction of human amniotic fluid. The method is based on measuring the difference in fluorescence of 1,6,-diphenyl-1,3,5-hexatriene added to amniotic fluid before and after micropore filtration. The filtration step removes "lamellar body" particles, which are considered to contain the fetal lung surfactant. The phospholipid values for the filtered particles are independent of background fluorescence, which increases when amniotic fluid is contaminated by bilirubin pigments or blood components. Over a wide range (3-150 mumols/L) the fluorescence increases linearly with the phospholipid concentration of the amniotic fluid. There is a good agreement between the value for particulate "lamellar body" phospholipid, the ratio of the "lamellar body" phospholipids to total amniotic fluid phospholipids, and the lecithin/sphingomyelin ratio.

Amniotic Fluid↗
PubMed1982

Comparison of the values for filter-trapped phospholipids with those for the lecithin/sphingomyelin ratio of amniotic fluid. A preliminary report.

A comparison was made between the lecithin/sphingomyelin ratio of amniotic fluid and the amount of phospholipids which could be removed from the amniotic fluid by filtration. We found a good correlation between the two methods. The amount of filter-trapped phospholipids can be determined within one and a half hours compared to three and a half hours for the lecithin/sphingomyelin ratio. It has a higher reproducibility than the lecithin/sphingomyelin ratio and can be performed with the aid of a simple filtration apparatus.

Amniotic Fluid↗
PubMed1981

Premature changes in surface activity in lung fluid of fetal lambs.

The present study was conducted to monitor changes in surface activity of lung and amniotic fluid of premature lambs. Lung fluid was continuously obtained from 10 tracheotomized fetal lambs (gestational age 98-112 days) until (premature) parturition. Amniotic fluid was sampled twice a week from 3 other lambs by catheterization, and during cesarean section at the end of the gestational period from another 3 lambs. Surface activity in lung fluid increased on the first postoperative day, the more so when this occurred at a later fetal age in the period of 98-112 days. These findings show that even before day 110 'stress' can result in a release of surface active material. A return to low surface activity (about 26 mN/m) was observed within 3 to 6 days. Thereafter, between days 110 and 120, surface activity increased steeply within the individual animals but with large variability between the fetuses. The steep and premature increased was followed by a further but slow increase during the mature period and Ymin values of approximately 2 mN/m were reached. Amniotic fluid surface activity changed slowly with gestational age, but did not reach Ymin values of less than 15 mN/m. Lung fluid total phospholipid phosphorus values were low (about 6 micro M) up to 125 days, when they increased rapidly (greater than 16 micro M). Lung fluid production increased from 4.9 ml/h at the beginning of the experiment to 12.1 ml/h after day 130 but decreased dramatically 1-3 days before (premature) parturition. Experiments on fetal lung maturation should be started before day 105 of gestation and we suggest that measurement of surface activity of fetal lung fluid may be useful in monitoring changes in the premature alveolar type II cells of lambs.

Amniotic Fluid↗
PubMed1979

[Relationship between the presence of meconium in newborn lambs and postnatal pH and blood gas tension levels (author's transl)].

The pH of the blood and blood gas tension (PO2 and PCO2) were estimated in thirty-two lambs. Blood was taken from the umbilical vein during labour and blood was collected from the left ventricle after birth (1, 10 and 60 minutes). The findings in twenty-one lambds were used to determine the relationship between the presence of meconium on the fleece and the postnatal changes in pH and blood gas tension. pH, blood gas tension and vitality were found to be identical both in the meconium-stained and in the unstained lambs. Within this experiment, there was no relationship between the length of parturition and pH and blood gas tension levels. The pH, PO2 and PCO2 as determined in the umbilical blood showed that the lambs (both meconium-stained and unstained) continue to be in good condition throughout a normal parturition. Postnatal adjustment is rapid and, following normal ventilation, pH, PO2 and PCO2 respectively attain levels of 7.379; 54.7 and 43.7 within sixty minutes. Diminished vitality, resulting from pathological factors, was observed in four lambs.

Animals↗
PubMed1978

[The presence of meconium in newborn lambs (author's transl)].

Meconium was present on the fleece of 114 newborn lambs in sixty-two per cent of the cases. It was observed in forty per cent of the firstlings of primiparae, whereas the highest proportion (eighty-two per cent) was seen in the group of the lambs of pluriparous ewes, which were born later. A short normal gestation period (less than 144 days), a low birth-weight (less than 4.0 kg.) and a short period of parturition appear to result in a reduced incidence of the presence of meconium.

Animals↗
PubMed1977

[Superfoetation following artificial insemination in a ewe (author's transl)].

A case of superfoetation following artifical insemination in a ewe is reported. Estimation of the age of the lambs was based on the maturity of the liver, lung, kidney, brown adipose tissue and skin, showing a difference in gestational age of approximately thirty-six days. The possibility of spontaneous superfoetation as well as that of a second fertilization after artificial insemination is discussed.

Animals↗
PubMed1976

Indication of increase of the lecithin/sphingomyelin (L/S) ratio in lung fluid of lambs maternally treated with metabolite VIII of Bisolvon.

Metabolite VIII of Bisolvon (Met. VIII) was administered to six pregnant ewes (i.m. daily 5 or 10 mg/kg for 7-9 days). The treatment was started at the 116th/117th or 117th/118th day of gestation and in one case the drug was given to the fetus (i.v. 2 mg/ml/h). Fetal lung fluid obtained from chronically implanted catheters was used for the estimation of the lecithin/sphingomyelin ratio. The maternal treatment with Met. VIII resulted in a significantly increased growth of the L/S ratio compared to the control group (n=4). In three lambs a sharp increase of the L/S ratio was noticed during the last days of Met. VIII treatment. The time gap between first treatment and noticeable effect was 6-8 days. It is postulated that the noticed increase of L/S ratio is the consequence of Met. VIII treatment and very unlikely the result of a release of glucocorticoticoids.

Ambroxol↗
PubMed1975

Pressure volume curves of lamb lungs and the lecithin-sphingomyelin ratios of lung fluid.

Pressure-volume curves were made of lungs from non-distressed, from asphyxiated and from distressed lambs. The curves of the non-distressed animals differed from the curves of the asphyxiated and of the distressed group. Eleven stability indices were calculated and the summation of these in situ surfactant characteristics was used for individual respiratory distress syndrome diagnosis. Low values (less than 2) of lecithin/sphingomyelin (L/S) ratios in lung fluid were found before the 130th day of gestation, but a steep increase of the L/S ratio was present after that period. Postnatal RDS was found in low L/S ratio cases, whereas normal lung stability was noticed in animals with L/S ratios greater than 2. It is concluded that the prenatal L/S ratio in lung fluid of lambs is of predicting value in RDS experiments and fits well with lung stability characteristics.

Animals↗
PubMedDate not supplied

Cerebral and aortic blood flow velocity patterns in preterm infants receiving prophylactic surfactant treatment.

Blood velocity in the internal carotid artery (ICA) and in the descending thoracic aorta (DAo) was investigated used Duplex-Doppler ultrasound in 14 infants of less than 30 weeks gestation, treated prophylactically with surfactant, and in 11 comparable infants with relatively mature lungs who served as controls. After surfactant administration, blood gases, pH or FiO2 were not different between the groups. Temporal mean blood velocity in the ICA was used as a relative measure of cerebral flow (TMFV-cer), and its coefficient of variation (CV-cer) was used to assess fluctuations in cerebral blood velocity. The pulsatility index (PI) in the ICA (PI-cer) and DAo (PI-DAo) was used to estimate if a left-to-right shunt was present. During surfactant instillation TMFV-cer was abnormally low and CV-cer indicated a fluctuating cerebral blood velocity. At 10 min after surfactant administration, TMFV-cer of the treated infants was higher compared to the controls, while CV-cer was stable in both groups. PI-cer and PI-DAo were abnormally high during the first hour of life after surfactant treatment, suggesting a left-to-right shunt without, however, clinical signs of a hemodynamically important ductus arteriosus. We suggest that cerebral perfusion is affected during and at 10 min after surfactant instillation. Left-to-right shunting appears to be a common event following surfactant treatment.

Aorta, Thoracic↗
PubMedDate not supplied

Comparison of the pulmonary surfactant content in alveolar macrophages of newborn, young, and adult rats.

The phospholipid composition of the 150-g pellet containing macrophages from neonatal lung lavages resembles that of surfactant. To study whether this composition reflects the surfactant content of the macrophage, we isolated the alveolar phospholipids and macrophages from the lavage fluids of fetal, newborn, young, and adult Wistar rats. The alveolar surfactant phospholipids increased from fetal levels of 2.8 nmol/mg dry lung weight (DLW) to 39 nmol/mg DLW at day 1, decreased sharply within the first week, and stabilized at a level of 2-4 nmol/mg DLW after day 15. The number of alveolar macrophages increased significantly during the first postnatal day from approximately 750 to more than 5000 (per mg DLW), decreased during the next 4 days, and varied strongly at older ages. We estimated the surfactant content in the macrophages semiquantitatively by polarization microscopy. Birefringence augmented significantly during the first 1.5 days after birth and decreased after that concurrently with the amount of alveolar surfactant. However, only cells without birefringent inclusions sedimented at 150g, whereas the phospholipid composition of the pellets falsely suggested that large amounts of intracellular surfactant were present in its cells. At least two populations of macrophages (surfactant-rich and surfactant-poor) are present in the growing animal. We suggest that differences in function of these various types of macrophages also might depend on surfactant congestion.

Aging↗