ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

To determine whether administration of human placental lactogen (hPL) to pregnant rats during late gestation might enhance fetal growth, we implanted osmotically driven minipumps to provide 75 μ h PL/24 h on day 14 of the rat's 21.5-day gestation. This substantially increased maternal and fetal plasma hPL concentrations. By day 18, hPL fetuses were significantly heavier and had larger placentas than controls. From this point until term, their rate of growth (1.20 g/24 h) significantly exceeded that of controls (0.95 g/24 h). Birth weights differed significantly (hPL 5.86 ± 0.08 g; controls 5.20 ± 0.08 g, p < 0.001). This increase was due primarily to significant increases in the growth of the liver and carcass. Enhanced glucose availability was in part responsible for this phenomenon inasmuch as plasma glucose concentrations were significantly increased in hPL maternal rats from days 15 to 19. This resulted on days 18 and 19 in significantly increased plasma glucose and insulin concentrations in hPL fetuses. Fetal/maternal glucose ratios did not differ between hPL and control fetuses. Fetal hepatic glycogen concentrations were significantly increased on day 18 and 19 but were similar to controls from day 20 until birth. These observations suggest that increased maternal glucose availability with consequent stimulation of fetal insulin secretion accelerated the growth of hPL fetuses. However, maternal and fetal plasma glucose concentrations and fetal plasma insulin and hepatic glycogen concentrations on days 20 and 21 were normal, suggesting that other factors also were responsible for sustaining the accelerated fetal growth on these days. These observations and the many reports of the stimulatory effect of placental lactogen upon numerous fetal metabolic functions suggest that hPL might have directly stimulated growth.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We have studied insulin resistance in a 12-year-old Japanese boy who presented with congenital generalized lipodystrophy. Oral glucose tolerance test exhibited a diabetic pattern with normal fasting plasma glucose. Results from euglycemic glucose clamp study showed decreases in both insulin sensitivity and responsiveness. Both the patient's erythrocytes and Epstein-Barr virus transformed lymphocytes showed low-normal insulin binding with a slight reduction in binding affinity in the latter. Insulin binding to the cultured fibroblasts was decreased due to a lowered affinity. In addition, they displayed a rightward shift of the insulin dose-response curve for D-14C-glucose uptake with no decrease in the maximum uptake. Insulin-stimulated autophosphorylation and kinase activity of the wheat germ agglutinin purified receptors from the Epstein-Barr virus-transformed lymphocytes appeared normal. The reason for some discrepancies in insulin binding among the cells remains unknown, and we cannot formulate a conclusion as to whether or not a primary binding defect of insulin receptors exists and contributes to insulin resistance in the patient. The decrease in insulin responsiveness demonstrated in the glucose clamp study may result from a defect at the rate-limiting step in the postbinding process of insulin action, presumably a defect in the glucose transport system in muscle tissues. The defect may be secondary to changes in in vivo circumstances.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Chediak-Higashi Syndrome (CHS) has been associated with recurrent bacterial infections and defective polymorphonuclear (PMN) leukocyte function. Confirmation of the diagnosis of CHS and defective PMN function was established in a 2-month-old with accelerated phase CHS. The diagnosis was confirmed by demonstrating reduced PMN degranulation (β-glucuronidase release 34.1 ± 0.9% versus 5.1 ± 4% and lysozyme release 17.6 ± 1.2% versus 11.1 ± .7% (control versus CHS) and staphylococcal bacterial killing at 15' 51.4 ± 3.6% versus 24.9 ±.4% (control versus CHS). Additional studies using fluorescent cytometric analysis were made to investigate other etiologies of PMN dysfunction in CHS. Total cell density and PMN granularity, as measured by fluorescent-activated cell sorter side scatter analysis, was no different from CHS and age-matched controls. Although CHS is characterized by large PMN granular inclusions, right angle light scatter analysis in this study suggests that the total cell density within the PMN of patients with CHS is normal (D <.01). PMN granular release of surface receptors was also studied using antibody binding and flourescent analysis. OKM1 antibody-binding demonstrated significantly reduced C3bi (MO-1) receptor expression (13% of control) p < 0.001. Decreased surface reception expression of C3bi receptors may play an additional role in defective PMN mobility, chemotaxis, and bactericidal activity in patients with CHS.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Reduced heart rate variability has been found in infants who later succumb to the sudden infant death syndrome (SIDS). To determine whether respiratory sinus arrhythmia, a major component of heart rate variability, is also reduced in SIDS victims, nighttime portions of eighteen 24-h recordings of ECG and respiration from infants who later died of SIDS and 52 recordings from control infants were assessed using spectral analysis. Two aspects of respiratory sinus arrhythmia were examined: “extent” (the absolute heart rate variation at the respiratory frequency) and “coherence” (the degree to which heart rate follows respiration regardless of the absolute amount of variation). Respiratory parameters were used to classify each 1-min epoch as quiet sleep, rapid eye movement sleep, waking, or indeterminate state. Median extent and coherence values across the night were then computed for each sleep-waking state. Two-way (group ± state) repeated measures analysis of variance tests were then used to compare respiratory sinus arrhythmia values for 13 SIDS victims and 13 control infants matched by postnatal age, birth weight, sex, and gestational age. Extent of respiratory sinus arrhythmia was significantly lower in the SIDS victims across all sleep-waking states, a finding that persisted after adjusting for heart rate. Coherence values did not differ significantly. These results suggest that even before the time of maximal risk for the syndrome, SIDS victims, as a group, differ from controls in the extent to which cardiac and respiratory activity couple, and this difference is independent of basal heart rate.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Comparison of the adult brain insulin receptor (IR) to other tissue IR demonstrates that the former migrates ∼10 kD faster on sodium dodecyl sulfate-polyacrylamide gel electrophoresis due to deficient sialic acid content of the asparagine N-linked carbohydrate moieties. We studied these receptors in the fetal rat (18-day) brain (∼125 kD) and liver (∼135 kD), and demonstrated that similar differences are present during fetal life. These differences are not modified by hyperglycemia associated with both mild hyperinsulinemia and normoinsulinemia/ hypoinsulinemia. We further studied the specific brain cell types: neurons, glial cells, and purified microvessel preparation, and demonstrated a heterogeneity in the N-linked glycosylation of the IR within an organ (brain). The neuronal (∼125 kD) and microvascular (∼125 kD, ∼135 kD) IR are deficient in sialic acid, thus conferring neuraminidase-insensitivity to the whole brain, whereas the glial cell IR, similar to the liver IR, exhibits neuraminidase sensitivity and migrates intermediate (∼128 kD) to the liver and brain IR. The functional significance of this receptor heterogeneity between various tissues and cells within the same organ (brain) remains to be determined.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

This study examines the effect of premature delivery on the switch from fetal (α2β2) to adult (α2β2) Hb, in lambs in which premature parturition was induced by the intrafetal infusion of ACTH or corticotropin releasing hormone. Of 10 chronically cannulated ovine fetuses given ACTH at the rate of 79 ng/min for a 15 min period every 2 h starting at days 125 (n = 9) or 126 (n = 1) of gestation, three died in utero at days 131, 131, and 130, respectively. The remaining seven were born alive at 133 ±1.6 days. Five control fetuses, treated with vehicle (0.9% NaCl, wt/vol) only were delivered at 149 ± 2.7 days of gestation, which is not significantly different from the duration of pregnancy in other chronically cannulated lambs in this flock. Hb switching, as measured by the globin synthesis ratio, β/α, was complete at term in the control lambs. The β/α globin synthesis ratio of the prematurely delivered lambs was not accelerated by birth, and was similar to that of control fetuses of the same gestational age still in utero. The four lambs surviving premature birth more than 70 days did not complete the switch to normal adult Hb until after 220 days postconception.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We measured bone mineral content (BMC) in 18 neonatal miniature piglets by single photon absorptiometry, total body calcium (TBC) by total body neutron activation analysis, growth, and serum indices of mineral status (calcium, phosphorus, alkaline phosphatase activity). Measurements were begun on day 6, when the piglets were weaned, and were continued to day 19. After weaning, the piglets were assigned randomly to receive one of three diets which differed only in their concentrations of calcium and phosphorus: 100% of the recommended level (diet A), 60% (diet B), and 20% (diet C). No differences were observed among groups during the 19-day study, either in weight gain (48 ± 2 g/day) or increment in crown-rump length (2.4 ± 0.2 cm/wk). BMC correlated significantly (p < 0.001) with TBC at 6 (r = 0.83), 13 (r = 0.77), and 19 (r = 0.93) days. BMC correlated significantly (p < 0.001) with the ash weight (r = 0.87) and calcium content (r = 0.90) of the corresponding tibial bone segment. Anthropometric parameters and serum indices of mineral status did not predict TBC as accurately as did BMC measurements. We observed a range in BMC measurements in this study that was similar to the range reported for infants in the 1st yr of life. The high correlation between BMC and TBC suggested that BMC is useful in the assessment of mineral status in infants.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

This study was performed to determine whether prostaglandins play a role in the increase in pulmonary blood flow in the fetal lamb caused by an increase in oxygen tension similar to that occurring at birth. To increase fetal oxygen tension without ventilating the lungs, nine pregnant ewes with chronically instrumented fetuses were exposed to 100% oxygen at 3 atmospheres absolute pressure for 20 min in a hyperbaric chamber. This exposure increased pulmonary arterial oxygen tension in the nine fetuses from 20 ± 1 to 54 ± 9 torr. It increased pulmonary blood flow from fetal to newborn values, 31 ± 3 to 295 ± 20 ml/kg/min. It did not change pulmonary arterial pressure, 52 ± 2 torr during normoxia and 50 ± 2 torr during hyperoxia. Treating five of these fetuses with 3.2 ± 0.4 mg/kg of indomethacin during hyperbaric oxygenation did not alter these effects (Po2= 51 ± 8 torr, pulmonary blood flow = 283 ± 13 ml/kg/min, and pulmonary arterial pressure = 48 ± 2 torr). We conclude that the increase in pulmonary blood flow caused by an increase in oxygen tension in the fetus is not maintained by prostaglandins.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

It is still uncertain whether the yolk sac is the only origin of hemopoietic stem cells during fetal development. We studied the level of circulating granulocyte/macrophage colony-forming unit (CFU-GM) from the 23rd week of gestation to fullterm, trying to delineate its role in the ontogeny of human hemopoiesis. Cord blood samples were collected from 45 healthy premature neonates and 91 healthy full-term neonates. CFU-GM assays were performed using a single agar layer system with human placental conditioned medium as a source of colony stimulating activity. The mean numbers of colonies produced from the cord blood samples of the premature and full-term neonates were 116 ± 185 (SD) and 96 ± 113/2 ± 105mononuclear cells, respectively. There was no statistical difference between the numbers of colonies of the two groups (Mann-Whitney test, p > 0.05). These results indicate that the level of circulating CFU-GM from the 23rd week of gestation to full term is constantly high and add credence to the assumption that CFU-GM are produced not only from the yolk sac but also from other hemopoietic sites.

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID