摘要:

Guinea pigs demonstrate “precocious” physical and functional development, with newborns displaying open eyes, hair, self-feeding, and temperature regulation. In addition, morphologic lung development is precocious in the guinea pig, with advanced alveolarization taking placein utero. To explore whether pulmonary surfactant development is also advanced, and at what stage prematurely delivered guinea pigs are capable of survival, we delivered fetal guinea pigs at 2- to 3-day intervals from day 49 of gestation to day 69 (birth). These were examined for chronologic changes in lung morphology, lung tissue disaturated phosphatidylcholine, phosphatidylglycerol and glycogen content, and serum glucocorticoid and thyroid hormone levels. Other prematurely delivered guinea pigs were given brief postnatal resuscitation and their survival noted. We confirmed advanced morphologic lung maturation, yet found that surfactant development, with antecedent hormone peaks and glycogen depletion, occurs during the final 10-15% of gestation. Lung biochemical development is thus “on time” in the guinea pig, rather than “precocious” compared to other frequently studied laboratory animals. In addition, >50% of fetal guinea pigs are capable of survival by 8 days prior to term, well in advance of premature survivability in other small-sized species. (Pediatr Res21: 427-431,1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

We have analyzed the lα,25-dihydroxycholecalciferol [1,25(OH)2D3] receptor content of cultured cells from human amniotic fluid. Six cell lines were grown to confluence in a minimum essential medium containing 20% fetal calf serum. All had a normal karyotype, five were male and one was female. Hypertonic cytosol extracts were prepared by sonication followed by centrifugation at 200,000 X g 30 min. Saturation analysis was performed by incubating the extracts with [3H]-1,25(OH)2D3(20-500 pM, 160 Ci/mmol) with and without 100-fold molar excess of unlabeled 1,25(OH)2D3. Linear sucrose gradient (5- 20% w/v) analysis was performed with 1.5 nM [3H]- 1,25(OH)2D3alone or in presence of 100-fold molar excess, 1,25(OH)2D3. Functional responsiveness was measured by induction of 25-hydroxycholecalciferol-24R-hydroxylase with 1 and 10 nM 1,25(OH)2D3. The six cell lines studied had receptors with dissociation constant of 44 ± 6 pM (mean ± SEM). The binding capacity was 10,200 ± 1,750 sites/ng protein (mean ± SEM) with extreme values of 4,700 and 15,500. A single peak for specific binding migrating at approximately 3S was observed by sucrose gradient centrifugation. 25-Hydroxycholecalciferol-24R-hydroxylase was induced by 1 and 10 nM 1,25(OH)2D3in a dose-dependent fashion. The data show that receptors for 1,25(OH)2D3are present in cultured amniotic fibroblast like cells early in pregnancy. These cells may thus prove to be useful for further characterization of 1,25(OH)2D3receptors in fetal tissue. (Pediatr Res21: 432-435, 1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Hyperinsulinemic rat fetuses were obtained either by repeated in utero injections of long-acting insulin (resulting in fetal hypoglycemia) or by chronically infusing intravenous glucose to the mother (resulting in fetal hyperglycemia). Fetuses were examined at term. In insulin injected fetuses (n=15), surfactant (S) fraction phosphatidylcholine (PC) and dis saturated phosphatidylcholine (DSPC) were significantly decreased (3.6 ± 0.1 nmol Pi/ mg tissue; p<0.001 and 2.8 ± 0.1 nmol/mg; p<0.025, respectively) as compared with their saline-injected controls (4.8 ± 0.2 and 3.3 ± 0.1 nmol/mg, respectively, n=19). However, residual (R) fraction was unchanged, and there was no difference in whole-lung phospholipids (combined S and R fractions). These results are consistent with morphological data showing a lower lamellar body area per type II cell profile in insulin-injected fetuses as compared with their controls [1.41 ± 0.13 µm2(n=72) versus 1.99 ± 0.14 µm2(n=129) p<0.01]. Glycogen content was slightly higher in insulin-injected fetuses (18.5 ± 1.0 Mg/mg, n=17) than in their controls (15.1 ±0.8 fig/mg, n=18; p<0.05). In the second model, changes in S fraction PC and DSPC were similar to those observed after insulin injections: 4.3 ± 0.25 and 3.4 ± 0.2 nmol Pi/mg in fetuses of glucose-infused rats (n=10) versus 5.7 ± 0.45 and 4.3 ± 0.3 nmol Pi/mg, respectively, in controls (n=10, p<0.05). In addition, PG was also decreased (0.24 ± 0.03 versus 0.40 ± 0.04 nmol Pi/mg, n=10; p<0.01), and in contrast with insulin injections, reductions of DSPC and PG were detectable in whole lung. However, glycogen content was unchanged by glucose infusion (13.7 ±1.0 µg mg, n=15 versus 14.0 ± 1.1 Mg/mg, n=20 in controls). In both models, the phospholipid composition of material recovered by lung lavage was unchanged. (Pediatr Res 21: 436-441,1987

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

To better characterize the effects of body position and exercise on urinary protein excretion, carefully defined random urine samples were obtained during recumbency and following both ambulation and exercise in healthy adolescent student athletes. Albumin, lysozyme, and N-acetyl-B-D-glucosaminidase were measured in all samples. Glomerular permeability and tubular function were assessed using the urinary albumin creatinine ratio (UAlb/UCr), the urinary lysozyme creatinine ratio (ULy/Ucr), the urinary N-acetyl-B-D-glucosaminidase creatinine ratio (UNa/UCr), and the urinary lysozyme albumin ratio (ULy/ UAlb)- UAlb/Ucr was significantly (p<0.001) lower in recumbent urine samples than in either ambulatory or post exercise samples, although no difference was seen between the latter two groups. Furthermore, recumbent UAlb/UCr was higher in females (/ 0.01) and post exercise UAlb/UCr varied significantly (p<0.001), depending on the type of physical activity. ULy/UCr, UNag/UCr, and ULy/UAlb were unaffected by either posture or physical activity. A significant correlation was found between UAlb/UCr(r=0.60, p=0.0001) and also between UNag/UCr and ULy/UAib (r=0.84, p=0.001). In addition, urine specific gravity was found to have a significant negative correlation with UAlb/Ucr (r=-0.33, p=0.001). The results of this study suggest that in the adolescent, recumbent albumin excretion is higher in females and that ambulation increases glomerular permeability. Exercise does not appear to induce any additional alteration in glomerular permeability, although the effects of exercise are likely related to the type and severity of physical activity. Renal tubular function is unaltered by either ambulation or exercise. Furthermore, urinary albumin excretion may be increased in the face of diuresis and urinary N-acetyl-B-D-glucosaminidase excretion may be stimulated by the effects of increasing albumin excretion. (Pediatr Res 21: 442-446, 1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

We studied the effects of anemia and ouabain administration on cardiac function, oxygen physiology, and blood catecholamine levels in nine newborn lambs. We measured oxygen consumption continuously, along with traditional hemodynamic variables. Oxygen transport was calculated. Following baseline measurements, lambs were made anemic (mean hematocrit=12%) by isovolemic exchange transfusion with Plasmanate, and measurements were repeated. Thereafter ouabain was administered as a 75μg/kg bolus, followed by 30 min of infusion at a rate of 0.05 μg/kg/min. Measurements were repeated at the conclusion of infusion. Anemia was associated with a heart rate related rise in left ventricular rate of pressure rise, a rise in oxygen consumption, an increase in cardiac output, a decrease in systemic vascular resistance, and a rise in fractional oxygen extraction (oxygen consumption/transport). Following ouabain administration, cardiac output, oxygen consumption, and stroke work fell, but left ventricular rate of pressure rise and the extraction ratio did not change. Serum levels of epinephrine and norepinephrine rose with sustained anemia and ouabain infusion. In this setting, ouabain effects are manifested primarily by alterations in oxygen transport and metabolism rather than by changes in traditional assessments of left ventricular contractile function. (Pediatr Res 21: 447-452,1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

We investigated the effect of the transient neonatal hyperthyroid state on thermogenesis at birth by measuring rectal temperature, plasma free fatty acids, plasma catecholamines, andin vitrobrown adipose tissue respiration in thyroidectomized (n=6) and sham operated (n=5) fetal sheep. Surgery was performed at an average of 133 days of gestation followed by cesarean delivery at 146 days. Fetuses were delivered into a constant room temperature of 25° C. Serial measurements were madein uterobefore delivery and at timed intervals after birth. Serum 3,3',5 triiodothyronine and thyroxine concentrations in the neonatal period were normal in sham operated and nondetectable in thyroidectomized fetuses. Rectal temperatures and serum free fatty acid levels were reduced in thyroidectomized newborns. Plasma epinephrine concentrations were increased and the hypothyroid neonates were acidotic when compared to control animals.In vitrobasal and norepinephrine stimulated brown adipose tissue respiration were reduced in thyroidectomized compared to control animals. These results indicate that thyroid hormone deficiency impairs non shivering thermogenesis in brown adipose tissue and leads to hypothermia despite augmented plasma epinephrine values.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Growth and nitrogen and energy balances were studied with a combined technique of nutrient balance and indirect calorimetry measurement in two groups of eight very low birth weight infants fed pooled pasteurized human milk (HM) or cow's milk casein hydrolysate supplemented HM (HM-Pr). There was no difference in the amount of energy absorbed (91 ± 17 kcal/kg/day with HM-Pr versus 95 ± 8 with HM-P) or in the growth rate. The infants fed HM-Pr had a higher nitrogen intake (602 ± 80 versus 395 ± 64 mg/kg/day; p<0.001), urinary nitrogen excretion (160 ± 64 versus 78 ± 16 mg/kg/day; p<0.005) and nitrogen retention (326 ± 32 versus 252 ± 48 mg/kg/day; p<0.01). They also had increased plasma concentrations of essential amino acids, urea nitrogen, and total protein without metabolic imbalance. Energy expenditure was higher (58 versus 49 kcal/kg/day; p<0.005) and energy storage lower (33 versus 47 kcal/kg/day; p<0.05) with HM-Pr. In percent of weight gain, protein and fat accretion represented 12 and 14% in HM-Pr group versus 10 and 27% in HM group. Very low birth weight infants fed casein hydrolysate supplemented pooled HM achieved a growth rate and a weight gain composition similar to the fetus. (Pediatr Res 21: 458-461,1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

We characterized the lipid-lipoprotein abnormalities encountered in a series of 45 nonnephrotic uremic children with various degrees of chronic renal insufficiency. A mild hypertriglyceridemia associated with decreased serum high-density lipoprotein cholesterol levels was confirmed. The correlation between high-density lipoprotein cholesterol and creatinine clearance showed a power behavior with a marked decrease in high-density lipoprotein cholesterol below a creatinine clearance value of 40 ml/min/1.73 m2A number of uremic children accumulate an abnormal population of very low-density lipoprotein particles in their plasma. On agarose gel electrophoresis these particles migrate as a slow moving pre-/β band and are clearly distinguished from the regular fast moving pre-/β very low-density lipoprotein band. This electrophoretic phenomenon has been called double pre-/β lipoproteinemia. The prevalence of double pre-£ lipoproteinemia increased significantly with the degree of impairment of renal function, reaching highest figures in patients on hemodialysis. Accordingly, the very low-density lipoprotein cholesterol/triglyceride ratio also was significantly increased. The double pre-/β lipoproteinemia phenomenon was not detected in any of the control, nonuremic subjects. The clinical importance of double pre-/? lipoproteinemia in uremic plasma is related to its possible atherogenic role. (Pediatr Res 21: 462-465,1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Based on experimental studies in mutant mouse strains, an imbalance between the rate of migration of neural crest cells and the rate of differentiation of the mesenchyme of the distal gut has been proposed as an etiological factor in Hirschsprung's disease. We studied the influence of the stage of differentiation of embryonal chick gut on the migration of neural crest cells in an in vivo culture system: the chorioallantoic membrane. Neural crest cells in cultured gut were demonstrated with antibodies directed against the HNK-1 epitope. Enteric neurons were demonstrated with neurofilament immunoreactivity. By culturing isolated gut segments of E4 embryos, we obtained aneuronal (neurofilament-negative) embryonal chick gut up to 25 days of development. In cocultures of aneuronal gut and the neural anlage (neural tube and neural crest) neural crest cell colonization was observed, even in advanced stages of differentiation. The significance of the results is discussed in terms of the etiology of Hirschsprung's disease. (Pediatr Res 21: 466-470, 1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Seven-day-old rats (15 g body weight) were injected subcutaneously with iodo-[14C] antipyrine (5 µCi). After a variable period, each pup was decapitated and arterial blood collected for scintillation counting. Brains were immediately removed and either prepared for isotopic counting or frozen for autoradiography. The brain:blood partition coefficient was determined [0.944 ± 0.006 ml/g (mean ± SEM)]. Both cerebral blood flow (CBF) and regional CBF (RCBF) were calculated according to a formula derived from the Fick equation. CBF equaled 66 ± 4 ml/100 g/min (mean ± SEM), a value midway between reported 1-day-old rat CBF and adult rat CBF. Autoradiographs were of sufficient quality to permit microdensitimetric readings of a minimum of 11 structures. RCBF ranged from 20 ml/100 g/min in subcortical white matter to 71 ml/100 g/min in the brain stem. Immature rat RCBF, as a proportion of adult rat RCBF, was greatest in brain stem. Previously thought not feasible, this technique provides a reliable and relatively simple means of measuring both CBF and RCBF in the very small laboratory animal.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID