摘要:

The high-density lipoprotein (HDL) subclass distribution was examined by gradient gel electrophoresis (gge) in 154 human cord blood samples, and determinations of triglyceride, total cholesterol, and HDL-cholesterol levels were performed. Three distinct gge patterns were recognizable. The first pattern, termed the normal (gge) pattern, was distinguished by a prominent double peak in the (HDL2a)ggeregion and a pronounced peak in the (HDL3b)ggeregion. Minor peaks, or shoulders, were also seen in the (HDL2b)ggeand (HDL3C)ggeregions, and a valley was present in the (HDL3a)ggeregion. This pattern was associated with normal lipid levels for cord blood plasma (mean triglycerides: 30-42 mg/dl; mean total cholesterol 62-85 mg/dl; mean HDL-cholesterol: 34-41 mg/ dl).The second pattern, termed the 2b(gge) pattern, contained a major peak in the (HDL2b)ggeregion rather than the shoulder seen in the normal (gge) pattern, while the (HDL2a)gge, (HDL3b)gge, and (HDL3c)ggeregions were less pronounced. This pattern was associated with elevated total cholesterol and HDL-C levels (means 85-102 and 49-56 mg/dl, respectively). The third pattern, termed the 3b(gge) pattern, was characterized by a paucity of material in the (HDL2b)ggeregion, a single peak in the (HDL2a)ggeregion, and either a relative increase in the (HDL3b)gge region, or a simultaneous increase in both (HDL3b)ggeand (HDL3c)gge. This pattern was associated with elevated triglyceride levels (means 78-88 mg/dl) and decreased HDL-C levels (means 20-30 mg/dl). Only two infants had a simultaneous elevation of triglycerides and total cholesterol and both cases exhibited the 3b(gge) pattern. Our study demonstrates that although the triglyceride and cholesterol levels in the newborn are much lower than those in adults, they are the important factors associated with the HDL subclass distribution. Elevated cholesterol was related to increased particles in the (HDL2b)ggeregion while elevated triglyceride levels were associated with a decrease in (HDL2b+2a)ggeparticles and a concomitant increase in (HDL3b)ggeparticles.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effect of smooth muscle tone on the functional characteristics of neonatal airways was studied in six newborn lambs. Tracheal mechanics, resistance, and collapsibility were determined in tracheal segments of uniform length which were surgically isolated just caudal to the cricoid cartilage. Resistance to airflow through uncompressed (zero transmural pressure) and compressed (increased transmural pressure) trachea was evaluated over a range of physiological flows both before and after induced contraction of airway smooth muscle. Results demonstrate that neonatal tracheal smooth muscle does respond to cholinergic stimulation and that there was a significant decrease in airway compliance. Furthermore, the consequent increase in airway rigidity may play a role in resisting collapse or compression of the intrathoracic airway during expiration.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The phagocytic and bactericidal capacities of ovine bronchoalveolar lavage (BAL) cells were investigated as a function of postnatal age. In addition, age-related changes in the elaboration by alveolar macrophages of chemotaxins for neutrophils, concentrations of BAL fluid and serum immunoglobulins, and serum opsonic capacity were determined. BAL cells exhibited major changes in morphology, composition, andin vitroproliferation during the 1st postnatal wk. Studies in germ-free Iambs indicated that the antigenic burden of the ambient environment markedly influenced the concentration of BAL neutrophils but had no effect on the influx, phagocytic, and proliferative activities of alveolar macrophages. Phagocytic and bactericidal functions of BAL cells improved rapidly during the 1st postnatal wk, then declined, and did not reattain adult levels until day 180. The capacity of alveolar macrophages to elaborate chemotaxins for neutrophils was deficient at day 8, but not at subsequent ages. The concentration of BAL IgG1increased until day 8, fell at day 21, and then continued to increase gradually. IgA was not detected in BAL until day 21 and increased rapidly thereafter. Serum opsonic capacity at days 1 and 4 was comparable to that of adult serum, but sera from days 8 to 42 showed a marked reduction in opsonic capacity. Pulmonary antimicrobial defenses in neonatal sheep were thus found to be deficient to some degree throughout the first 3 months of life. It was not until day 180 that the parameters investigated in this study approximated those of adult sheep.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The extent of in vivo lipid peroxidation and thein vivoantioxidant effects of α-tocopherol and α-tocopheryl acetate were studied in newborn rabbits exposed to one of two oxidant stresses: hyperoxia (Fio20.9) or parenteral lipid emulsion infusion. Lipid peroxidation was monitored by measurement of expired ethane and pentane, tissue thiobarbituric acid (TBA) reactants, and tissue lipid peroxides. Seventy-two h of hyperoxia did not increase any of the parameters of lipid peroxidation although mortality was higher in oxygen exposed animals. α-Tocopherol (100 mg/kg, intravenous) lowered expired hydrocarbons and tissue TBA reactants, but raised liver lipid peroxides in both air and hyperoxia exposed pups. Infusion of soybean oil emulsion increased production of ethane and pentane, liver TBA reactants, and lung lipid peroxides. Both α-tocopherol and α-tocopheryl acetate prevented the soybean oil emulsion induced increase in volatile hydrocarbons, α-Tocopherol (100 mg/kg, intravenous) administration also prevented the increase in liver TBA reactants and lung lipid peroxides. In identically treated animals, α-tocopheryl acetate administration decreased liver TBA reactants but had no effect on lung lipid peroxides. We conclude that α-tocopherol reduces lipid peroxidation in newborn rabbits including animals exposed to hyperoxia or infused with lipid emulsions. α-Tocopheryl acetate results in lower tissue α-tocopherol concentrations and is less effective as an antioxidant in lipid emulsion infused rabbits.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The auditory brainstem response (ABR) was monitored in nine infant rhesus monkeys during the intravenous infusion of 50-168 mg/kg of unconjugated bilirubin. Sulfisoxazole (200 mg/kg) was sometimes given near the end of or just before the bilirubin infusion if no obvious ABR change had yet occurred. Five of the animals were term gestation, four were preterm, and they ranged from 1 to 40 days of age at the time of study. The three oldest term animals, studied at 20, 35 and 40 days of age, respectively, showed variable changes in the ABR waves during bilirubin infusion and these changes were not altered further by sulfisoxazole administration. The other two term infants, studied at 1 and 6 days of age, respectively, showed sulfisoxazole enhanced ABR wave latency increase and amplitude reduction followed by loss of the ABR. Both of these animals became apneic following ABR loss and eventually died. The ABR reappeared in one animal prior to death. Minimal gross and microscopic changes were present in the brain of the 6-day-old animal at autopsy. The four preterm animals all had a progressive wave amplitude decrease followed by loss of the ABR with bilirubin alone. These preterm animals were sacrificed shortly after the ABR loss with only one showing yellow staining of the basal ganglia at autopsy. The infant rhesus monkey may be a useful paradigm for bilirubin-induced ototoxicity as manifested by potentially reversible ABR changes. The changes are dependent on gestational and chronological age of the animal and appear to occur in the peripheral eighth nerve or cochlea as well as in brainstem pathways. (Pediatr Res 20: 511-515,1986)

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Autoregulation of cerebral blood flow has been demonstrated in both fetal and newborn animal models under normoxic conditions. In the present experiments we have attempted to define the minimal hypoxic insult which impairs autoregulation in the newborn Iamb and to assess the time to recovery. We measured cerebral blood flow by the intracarotid133Xe method in fifteen 4- to 9-day-old lambs and tested autoregulation of cerebral blood flow by increasing blood pressure 20-30% with phenylephrine. Autoregulation was tested in the control state and at successive time intervals after an hypoxic stress (Pao2of 30 mm Hg) of 10 or 20 min. We found that cerebral autoregulation was abolished after 20 min of hypoxia and recovered within 7 h. Since this model identifies the minimal hypoxic insult to abolish autoregulation it might be used to study means to protect autoregulation or to hasten its recovery after hypoxia. (Pediatr Res 20:516-519,1986)

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

In order to determine whether cystic fibrosis neutrophils are affected in their secretory functions, lysosomal enzyme release and chemiluminescence (light emission from cells) were assayed in patients' cells and compared with those in normal control cells. We observed a decreased response of cystic fibrosis neutrophils in β-glucuronidase release and chemiluminescence after stimulation by N-formyl-methionyl-leucyl-phenylalanine. There was no significant correlation of these results with the clinical score nor with the medical treatment. On the other hand, responses to the calcium ionophore A23187 and to opsonized zymosan showed no significant difference between normal and cystic fibrosis subjects in lysosomal enzyme release. N-formyl-methionyl-leucyl-phenylalanine receptor alterations did not seem involved in the observed effect as demonstrated by Scatchard plot analysis of N-formyl- methionyl-leucyl-phenylalanine binding to these receptors. These results clearly demonstrate a difference between normal and cystic fibrosis neutrophils in release and chemiluminescence responses to N-formyl-methionyl-leucyl- phenylalanine stimulation, a difference that might be located in the plasma membrane as both responses are membrane dependent. (Pediatr Res 20: 520-526,1986)

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To study postheparin plasma lipase activities in nonfed newborn infants immediately after birth and to investigate the possible influence of fetal hyperinsulinemia on lipoprotein lipase activity, we measured lipoprotein and hepatic lipase activities in 55 macrosomic newborn infants: group I consisted of 21 infants born to mothers with insulin-dependent diabetes. The infants were hyperinsulinemic at birth and had hypoglycemia and poor lipolysis at the age of 2 h. Group II consisted of 18 infants born to mothers with gestational diabetes. Group III consisted of 16 large-for- date infants born to nondiabetic mothers. The mean postheparin plasma lipoprotein lipase activities at 2 h of age were similar (mean 36 μmol free fatty acids/ml/h; SEM 15) in groups I—III. Lipoprotein lipase activity correlated negatively with cord-serum triglycerides (range 0.13-1.2 mmol/liter) but did not correlate with serum insulin (range 5.4-524 μ U/ml) or C-peptide (range 0.6-21.0 μg/liter). Hepatic lipase activity was somewhat higher in group I (mean 68 μmol free fatty acids/ml/h; SEM 23) than in groups II and III (mean 55 μmol free fatty acids/ml/h; SEM 14). Hemoglobin Ale was the only important factor explaining the difference in hepatic lipase activities between groups. Lipoproteins and apolipoproteins A-I, A-II, and B were similar in all three groups. We conclude that in large-for-date infants lipoprotein lipase is active at birth without exogenous fat induction, and that these infants are capable of hydrolyzing fat, their main source of energy, immediately after birth. In addition, we conclude that postheparin plasma lipoprotein lipase activity is not affected by fetal hyperinsulinemia. (Pediatr Res 20: 527- 531,1986)

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

We have previously shown that the healthy fetal lamb liver does not release glucose and does not demonstrate gluconeogenesis. Shortly after birth, however, the liver releases glucose both by glycogenolysis and by gluconeogenesis. Previously it has been suggested that increased oxygen availability stimulates hepatic gluconeogenesis at birth. To test this hypothesis, we increased fetal arterial blood pO2by ventilating the fetus with high oxygen gas mixtures in utero. We placed intravascular catheters in the right or left hepatic vein, umbilical vein, inferior vena cava, and descending aorta and inserted a large polyvinyl tube into the trachea of seven fetal lambs at 134 ± 2.2 days gestation. Studies were done several days after surgery.14C-lactate was infused intravenously andI4C-glucose concentrations were measured in hepatic venous and umbilical venous blood during a control period, during ventilation with 5% CO2, 3% O2, 92% N2, and then during ventilation with 5% CO2and 95% O2. The difference between these two measurements represented hepatic gluconeogenesis. Arterial blood glucose concentrations and blood gases were also measured during each study period. Ventilation with 3% O2did not significantly change arterial PO2but ventilation with 95% oxygen increased mean arterial pO2from a control of 16.7 to 156.3 torr. Mean arterial blood glucose concentration increased significantly from a control of 11.9 to 17.6 mg/dl during ventilation with 3% O2and to 19.1 mg/dl during ventilation with 95% O2. However, the hepatic-umbilical venous14C-glucose concentration difference was not significant when control values were compared with each ventilation period. We conclude that an acute increase in fetal oxygenation does not stimulate hepatic gluconeogenesis in near-term fetal lambs. (Pediatr Res 20: 532-535,1986)

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID