摘要:

We examined the acute effects of a change in hemoglobin oxygen affinity (P50) on systemic oxygen transport and oxygen consumption during hypoxia. Ten awake, intact, newborn lambs were studied during four consecutive conditions: normoxia (Fio2=0.21); hypoxia (Fio2=0.10); hypoxia after isovolemic exchange transfusion, raising P508 ± 3 Torr without changing hematocrit; and normoxia after the exchange transfusion. With hypoxia, oxygen extraction rose, cardiac output increased minimally, and systemic oxygen transport and oxygen consumption fell. After exchange transfusion during hypoxia, oxygen consumption rose to resting levels due to a significant augmentation of systemic oxygen transport, which resulted from an increase in cardiac output. This change in cardiac output was due to an increased stroke volume, most likely due to an improved inotropic state. The above findings are consistent with observations in newborn infants with respiratory distress syndrome who underwent exchange transfusion.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Using isopycnic gradient centrifugation, blood samples from adults, from umblilical cord, from newborn infants and from infants of different age group up to the age of 8 mo, were separated into seven fractions according to cellular age. We measured the number of erythrocytes and reticulocytes, mean cellular volume, mean cellular hemoglobin concentration, and the concentration of hemoglobin in each of the seven fractions. The distribution of erythrocytes within the gradient during postnatal aging revealed a bimodal distribution between 2-4 mo. Correspondingly, during the age of 2-8 mo the oldest cells did not contain the highest hemoglobin F concentration as was observed in the younger age group. From these data we conclude that the postnatal disappearance of hemoglobin F is not a continuous process.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Using weanling mice of two different genetic strains we demonstrated a potentiation of the toxic effects of acetaminophen by prior infection with influenza B virus. The C57BL/6N (B6) strain of mice is genetically predisposed to increased toxicity from acetaminophen when the hepatic cytochrome P-450 mixed function oxidase system is preinduced. When B6 animals are pretreated with influenza B virus and an mixed function oxidase system inducing agent before administering acetaminophen, we observed a significant incidence of atypical “fatty” liver pathology on light microscopy similar to the microvesicular steatosis seen in human Reye's syndrome. Electron microscopic changes in the liver of these animals resemble those published to date in human Reye's syndrome.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The effect of hypoxemia on arginine vasopressin (AVP) and oxytocin (OT) release was investigated in the chronically catheterized fetus and ewe. During 30 min of 10% maternal oxygen delivery, mean (±SEM) arterial Po2decreased from 105 ± 10.6 to 48 ± 3.5 mm Hg in the ewe and from 21 ± 1.3 to 12 ± 0.8 mm Hg in the fetus (each P< 0.001). Arterial Pco2decreased from 35 ± 44 to 29 ± 1.0 mm Hg in the ewe, whereas fetal Pco2decreased from 43 ± 2.3 to 35 ± 3.5 mm Hg (P< 0.05). Blood pH increased from 7.44 ± 0.03 to 7.56 ± 0.04 in the ewe (P< 0.01) and from 7.36 ± 0.004 to 7.40 ± 0.006 in the fetuses (P< 0.01). Baseline mean AVP levels were identical in ewes and fetuses (0.7 ± 0.1 µ μ U/ml). After 30 min of hypoxia, plasma AVP levels remained unchanged in the ewes (0.9 ± 0.1), but increased dramatically in the fetuses (47 ± 21 µ μU/ml) (P<0.001). There was a highly significant correlation between the duration of hypoxia and log fetal AVP concentrations (r=0.85). The log fetal plasma AVP also was inversely correlated to the log fetal Po2values (=0.83). Mean baseline fetal and maternal plasma OT levels were 2.6 ± 0.5 µ μU/ml and 2.2 ± 0.5 µ μU/ml, respectively. After 30 min of hypoxia fetal and maternal OT values were 2.9 ± 0.8 µ μU/ml (not significant).

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Previous studies have shown that triiodothyronine (T3) enhances the effect of dexamethasone on phosphatidylcholine (PC) synthesis in organ cultures of fetal rat lung. The aim of this study was to investigate whether similar interactions occurred in vivo and to explore possible mechanisms for this phenomenon. Injection of 7.0 mg/kg T3into pregnant rats on d 18 and 19 of gestation resulted in a mean fetal serum T3level of 2380 ng/dl on d 20 (control, 84 ng/dl) and in maximal (34%) stimulation of choline incorporation into PC. Injection of 1.0 mg/kg betamethasone using the same protocol as for T3resulted in maximal stimulation of 33% and administration of both hormones together produced a 69% increase, an additive affect. The percentage of PC that was disaturated was increased with betamethasone, but decreased with T3. Betamethasone treatment resulted in an increase in the whole lung disaturated PC content, but treatment with T3did not. Betamethasone administration also increased fetal serum T3levels, but T3injection did not produce elevated fetal serum corticosterone levels. Injection of T3in vivo, or exposure of explants of 18-d fetal lung to 100 nm T3for up to 48 h did not result in an increase in cytoplasmic glucocorticoid binding or nuclear translocation of the receptor steroid complex. Exposure of explants to glucocorticoid or T3in vivo or in culture (dexamethasone, 100 nM and T3, 100 nM; for 48 h) resulted in a significant increase in the activity of cholinephosphate cytidylyltransferase, an enzyme in the choline incorporation pathway of PC synthesis. Exposure of explants to the combination of hormones resulted in stimulation that was equal to the sum of that produced by the single hormones but was not statistically significantly different from the glucocorticoid effect. The activities of other enzymes of phospholipid synthesis were not increased by exposure to either hormone, in vivo or in vitro. The additive effects of T3and glucocorticoid with regard to choline incorporation into PC in fetal rat lung suggest that combined hormone therapy may be useful for the prevention of respiratory distress syndrome in humans. Further animal studies are required, however, before clinical use can be considered.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Although growth hormone (GH) concentrations are not always pathologically elevated in patients with acromegaly, it has been suggested that the metabolic and somatic consequences of this condition may be due to a loss of the normal episodic secretion of GH. To examine the effects of maintaining modest but constant levels of circulating GH, we administered continuous subcutaneous infusions of growth hormone (CSIGH) to eight previously untreated GH-deficient children (6-19 yr). CSIGH given for 90 h in doses equivalent to the standard dose for replacement therapy, raised mean serum GH levels from less than 3.0 to 5.9 ± 1 .0 ng/ml. In comparison, 24-h mean GH levels in five normal adolescents averaged 10.1 ± 1.5 ng/ml. As expected, however, normals showed much more variability in GH concentration. The constant elevations in serum GH levels achieved with CSIGH produced significant impairment of oral glucose tolerance. During CSIGH, plasma glucose concentrations 60-120 min after oral glucose loading were 30-40 mg/dl higher than corresponding pre-infusion values (P< 0.01). This impairment of oral glucose tolerance during CSIGH occurred despite a doubling of the area under the insulin/time curve after oral glucose (P< 0.02 versus pre-infusion area). Indeed, plasma insulin levels after oral glucose in patients on CSIGH exceeded those observed in normal controls, suggesting that CSIGH,had induced a degree of insulin resistance. There was a transient increase in plasma free fatty acid levels on the first day of CSIGH. Somatomedin-C concentration remained unchanged in four of six patients. We conclude that small but sustained increases in growth hormone concentrations in GH deficiency can, when infused continuously, have effects on fuel metabolism similar to those observed during pathologic GH hypersecretion.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A method was developed for the measurement of the binding of [3H]5α -dihydrotestosterone, [3H]DHT and other steroids at equilibrium with intracellular androgen receptor of genital skin fibroblasts. This method utilized 0.2 M Na2MoO4to stabilize the receptor and Sephadex G-25 chromatography to eliminate steroid metabolism. This binding protein showed the expected limited capacity, high affinity, and specificity of an androgen receptor. Using this method, penile skin cultures from 26 infants with simple hypospadias (HS) were compared with 18 controls. The [3H)DHT binding capacity (Bmax) was 10.1 ± 1.3 (±SE) fmol/mg protein for controls and 6.1 ± 1.7 for HS. The two populations were significantly different by Mann-Whitney test (P< 0.001). Equilibrium dissociation constant was similar for both groups. Surprisingly, there was no correlation between Bmaxand the severity of the anatomic defect. Bmaxwas below the values seen in HS for two of three infants with male pseudohermaphroditism. In complete androgen insensitivity, DHT binding was unmeasurable. A subgroup exists in HS with an abnormality of intracellular androgen receptors. The lack of correlation between severity of hypospadias and Bmaxsuggests that additional factors, such as differences in physicochemical properties of the receptor or factors present in utero, contribute to the development of HS.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Protective effect of pertussis vaccine (PV) against the development of insulin-dependent diabetes (IDD) induced by streptozotocin (STZ) in young CD-I male mice were studied. When PV at a dose of 1.2 X 1010microorganism was administered on —10, 0, or +4 d relative to a single injection of STZ (60 mg/kg body wt) on d 0, it completely aborted the development of IDD after 140 d. When PV was given on +30 d after STZ injection and followed by PV booster injections, 66% of mice reverted to normoglycemic state. Intact islet cells in the pancreas were confirmed by histologic findings and normal plasma insulin values. The effect of PV was compared with that of boiled PV in another model of IDD induced by multiple injections of STZ (40 mg/kg for five doses). In this model, 60% of mice either remained or reverted to normoglycemic state with PV and booster injections whereas boiled PV protected 40% of mice from developing IDD. The protective effect appeared to reside in the biologic property of both pertussigen and endotoxin of Bordetella pertussis.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID