ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The aim of this study was to investigate the effects of an abundance of unsaturated fatty acids, hyperoxia, and vitamin E on free radical formation in vitamin E-deficient rats. The excess of unsaturated fatty acids was achieved by i.v. administration of a lipid emulsion (Intralipid). To assess free radical formation, we measured the autooxidative susceptibility of red blood cells (AOS) and the thiobarbituric acid reacting substrates (TEARS) in LDL and HDL. Intralipid significantly increased all the measured parameters compared with controls (AOS: 1385 ± 73versus1056 ± 55; LDL-TBARS: 4955 ± 422versus1050 ± 33; HDL-TBARS: 6855 ± 573 versus 1033 ± 26 nmol TBARS/mmol). Hyper-oxia alone increased AOS more than Intralipid alone, whereas LDL- and HDL-TBARS concentrations were affected less by hyperoxia than lipid emulsion. The combination of hyperoxia and Intralipid was most effective in raising all measured parameters (AOS: 2285 ± 141; LDL-TBARS: 6716 ± 318; HDL-TBARS: 14614 ± 1000 nmol TBARS/mmol). Vitamin E completely prevented the increase in AOS, LDL-TBARS, and HDL-TBARS without fully reversing the increase in free radical formation caused either by Intralipid or by the combination of hyperoxia and Intralipid. These findings suggest that vitamin E supplementation is beneficial to counter increased free radical formation, such as that in response to hyperoxic attacks or lipid-containing parenteral nutrition, which is frequently encountered in the treatment of premature infants.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Ischemia-reperfusion injury may affect morbidity and mortality in preterm and asphyxiated term infants. Reoxygenation of hypoxic tissues leads to the formation of free oxygen radicals by xanthine oxidase that may induce lipid peroxidation, enzyme inhibition, and DNA strand breakage. We measured arterial cord blood samples from 36 healthy term infants for baseline values and arterial blood sampled at 1 and 4 h after birth from 45 preterm infants admitted for intensive care for serial estimates of plasma xanthine oxidase activity and lipid hydroperoxide levels. Mean ± SEM plasma xanthine oxidase activity in cord blood of term infants was 2.3 ± 0.4 mU/mL and lipid hydroperoxide levels were 2.6 ± 0.3 nmol/mL. Eighteen of the 45 preterm infants met the criteria defining poor out-come (poor outcome group) and had lower umbilical arterial pH and base excess than the 27 preterm infants in the control group. Mean plasma xanthine oxidase activity increased from 2.7 ± 0.4 at I h to 4.7 ± 0.6 mU/mL at 4 h of age (p< 0.001) in the poor outcome group and decreased from 2.1 ± 0.3 to 1.1 ± 0.2 mU/mL (p= 0.004) in the control group. Lipid hydroperoxide levels in the poor out-come group increased from 2.8 ± 0.6 nmol/mL at 1 h to 4.3 ± 0.6 nmol/mL at 4 h of age (p< 0.001) and decreased from 2.1 ± 0.6 to 1.6 ± 0.2 nmol/mL (p= 0.008) in the control group. At 4 h of age, xanthine oxidase activity and lipid hydroperoxide levels were significantly higher in the poor outcome group than in the controls (p< 0.001). We conclude that serial measurements of plasma xanthine oxidase activity and lipid hydroperoxide levels may identify critically ill preterm infants destined for major neonatal morbidity and mortality and may be clinically useful as an indicator of severity of acute perinatal hypoxia-ischemia.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Carnitine plays a central role in lipid metabolism by transporting long-chain fatty acids into the mitochondria for β-oxidation. Reduction of carnitine concentration does not automatically imply that functional carnitine deficiency exists with direct consequences on energy metabolism. In our experimental model, we reduced tissue concentrations of carnitine to levels that are comparable to those in patients with various metabolic disorders with secondary carnitine deficiency and did a study on thein vivoeffects of moderate carnitine depletion on palmitate oxidation, exercise capacity, and nitrogen balance. Thirty rats were divided into a carnitine-depleted group (group I) and pair-fed controls (group II). Carnitine depletion resulting in a 48% reduction of tissue carnitine concentrations was induced by feeding ad libitum a carnitine-free oral diet consisting of parenteral nutrition solutions. Palmitate oxidation was measured by collecting expired14CO2after an intraperitoneal injection of [l-14C] palmitate, and exercise capacity was determined by having the rats swim to exhaustion. Despite the 48% depletion of carnitine in serum, muscle, and liver, there were no differences in cumulative palmitate oxidation in 3 h (group I, 40 ± 7%; group II, 37 ± 9% of injected activity), swimming time to exhaustion (group I, 8.1 ± 2.8 h; group II, 7.7 ± 3.6 h), or nitrogen balance (group I, 1.1 ± 0.5 g of nitrogen/kg/d; group II, 1.2 ± 0.5 g of nitrogen/kg/d). We conclude that carnitine depiction of 48% has no effect on palmitate oxidation, exercise capacity, or nitrogen balance in the rats studied.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

To determine effects of diabetic gestation on plasma concentration of the coagulation regulatory protein, protein C, pregnant ewes were given glucose infusions to raise plasma glucose to twice baseline concentration or insulin infusions to lower glucose concentration to half baseline value. Control animals received no infusions. Concentrations of protein S, factor X, and antithrombin III were determined for comparison. Concentrations of glucose, insulin, and those above were determined thrice weekly for 2–9 wk. Short-term (8–12 h) infusions of glucose or insulin were performed to isolate their effects on concentration of protein C. Results were analyzed using a two-tailedttest, and protein C concentrations were further analyzed using a full linear mixed-effects model. In long-term infusions, hyperglycemia-induced hyperinsulinemia (mean insulin concentration 141 μU/mL) exerted negative effects on maternal concentrations of protein C [0.69 U/mL,n(number of samples) = 32, experimental versus 0.97 U/mL,n= 157, control], protein S (0.86 U/mL,n= 31, experimental ver-sus 1.04 U/mL,n= 109, control), and factor X (0.89 U/mL, n = 31, experimental versus 1.08 U/mL, n = 109, control); it exerted no effects on antithrombin III (1.05 U/mL,n= 23, experimental versus 1.04 U/mL,n= 32, control). The fetal lamb did not respond to chronic moderate hypergly-cemia (mean 33 mg/dL) with a consistent change in insulin concentration (mean 10 versus 9 μU/mL): no coagulation protein changed. In contrast, fetal hypoglycemia resulted in decreased fetal plasma insulin (5 μU/mL versus 10 μU/ mL) and a corresponding increase in protein C (0.56 U/mL, n = 17, experimental, versus 0.48 U/mL,n= 180, control) protein S (0.65 U/mL, n = 17, experimental versus 0.44 U/mL,n= 87, control), factor X (0.31 U/mL,n= 16, experimental versus 0.24 U/mL,n= 86, control), and antithrombin III (0.96 U/mL, n = 14, experimental versus 0.84 U/mL,n= 32, control). Insulin concentration varied inversely with protein C concentration when all groups were considered together and accounted for 12% of the variability of protein C concentration in control ewes. Glucose was not found to exert an independent effect on protein C concentration within any study group but was significant when all groups were considered together. Short-term studies confirmed the long-term infusion findings in the maternal group with hyperglycemia-induced hyperinsulinemia. These studies indicate that hyperglycemia-induced hyperinsulinemia may predispose to hyperco-agulability and thrombosis in the diabetic ewe and her fetus.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Alkylglycerols (AG) are glyceryl ether lipids and are present in human and cow's milk and the hematopoietic organs such as bone marrow, spleen, and liver. The bio-logic effects of AG include stimulation of blood leukocyte and thrombocyte production and activation of macrophage and anti-tumor activity. The present study was conducted to determine the effects of dietary AG in lactating rats on AG levels in milk and development of certain immune responses in the pups. Lactating rats were fed diets supplemented with various levels of AG. Milk samples were expressed from the dams and blood was collected from the pups on postpartum d 8, 16, and 24. Concentrations of AG in milk from the dams fed AG were significantly greater than those of the controls (p< 0.05). Peripheral blood granulocytes were significantly elevated in pups from the dams fed AG, but there were no differences in peripheral blood lymphocyte numbers. Plasma levels of immunoglobulins were significantly greater for IgG (p< 0.01) and IgM (p< 0.001) in pups from the dams fed AG than in the control pups. The supplementation of AG in the diets of lactating dams significantly elevated AG levels in the milk, and the increased AG in the milk subsequently stimulated certain immune responses in the pups.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Infants of less than 32 wk gestation have a defective epidermal barrier, with increased skin permeability and transepidermal water loss (TEWL). We studied the effect of a nonadhesive semipermeable dressing on the epidermal barrier of premature infants and on fetal skin transplanted to nude mice. Fifteen infants with a mean estimated gestational age of 27.7 wk and 16 human fetal skin grafts (estimated gestational age, 23–26 wk) transplanted to eight nude mice were studied. One lower leg (or skin graft) was treated and the other left untreated as a control. In the infants, TEWL was measured on control skin and treated skin (both through the dressing and after temporary dressing removal) on d 0, 1,2, 4, and 7. Bacterial and fungal cultures were also performed. In the mice, TEWL and skin blood flow were measured on d 0, 2, and 4. Biopsies were obtained on d 4 for a cell proliferation assay, histology, and electron microscopy. Treated infant skin showed a consistently lower bacterial number and a significantly decreased TEWL (measured through the dressing). There was also a significantly lower TEWL on the treated side, measured after temporary dressing removal, on d 1, 2, 4, and 7, documenting improved epidermal barrier function. The animal study revealed decreased TEWL and a nearly 2-fold greater d-4 keratinocytc proliferation (p= 0.01) in treated skin and decreased blood flow on d 4 in control skin (p= 0.01). There was no significant difference in the volume density of membrane coating granules or the morphology of intcrcorneocyte spaces. It is concluded that semipermeable dressings improve epidermal barrier function without increasing bacterial or fungal colonization in premature infants, and that increased cellular proliferation is associated with improved barrier function in semipermeable dressing-treated fetal skin.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

In a previous work, we reported that passive immunization with anti-growth hormone-releasing hormone (GHRH) anti-bodies (GHRH-Ab) in neonatal rats caused disruption of somatotropic function that was still present 60 d posttreatment. We studied the reversibility of this condition by growth hormone (GH) replacement therapy. Neonatal rats received GHRH-Ab (50 μ L/rat, s.c.) or normal rabbit serum every second day from birth up to postnatal d 10 and received hGH (0.4 μg/g body weight, s.c, b.i.d.) or vehicle in a 2 χ 2 factorial design. Animals were studied on d 11 of age. In GHRH-Ab-treated rats, GH therapyl) counteracted the reduced body weight and low plasma IGF-I levels;2) failed to modify the reduced pituitary weight and GH content;3) further reduced the low plasma GH levels;4) partially restored the defective GH responsiveness to GHRH;5) failed to modify the reduced hypothalamic somatostatin and increased GHRH gene expression in the hypothalamus; and6) reverted the decreased pituitary somatostatin binding. Morphologic and morphometric evaluation of the pituitary gland from GHRH-Ab+GH pups showed that the number of GH-labeled structures was lower than in normal rat serum-GH-treated pups, whereas the total GH immunorcactrvify per unit surface, an index of intracellular hormone concentration, was slightly higher than in vehicle-GH or GHRH-Ab pups. As determined by electron microscopy, somatotropcs from GHRH-Ab+GH pups had morphologic features of high cellular activity. It appears that in GHRH-deprived pups GH replacement therapy can normalize most but not all altered indices of the somatotropic function. The effects of GH are mainly directed at the pituitary, whereas the sensitivity of the hypothalamus to GH replacement is lower.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

A retrospective study is reported assessing final height (FH) and its predictive factors in 52 patients (31 male, 21 female) who underwent renal transplantation (RTx) before the age of 15 y. They received prednisone daily or on alternate days as well as azathioprine. The study period covered 20 y. FH remained below the third height percentile [height standard deviation score for chronologic age (hSDSCA) < −1.88] for most of these patients (77% males, 71% females). Median (range) FH was 165.0 (143.0–176.8) cm in males and 153.0 (135.0–168.4) cm in females. Median difference between FH and target height was 15.0 and 15.4 cm for males and females, respectively. For both sexes, the median hSDSCAwas already below −1.88 at the start of the first hemodialysis, after which it decreased significantly until the first RTx. After RTx, there was no significant improvement of hSDSCA. The predictive factors for FH were determined by evaluating various factors simultaneously in a multiple regression analysis. This analysis provided a regression equation for predicting FH. A higher hSDSCAat the time of the first RTx and alternate-dayversusdaily prednisone therapy both had a significantly positive influence on FH, whereas a longer duration of reduced GFR (<50 mL/min/1.73 m2) had a significantly negative effect on FH. Other factors such as age or bone age at first RTx, primary renal disease, duration of initial dialysis, repeat RTx, and the cumulative dose of prednisone did not influence FH significantly. In conclusion, 71–77% of patients that received their first renal transplant before the age of 15 ended up with severely short adult stature. Optimization of the hSDSCAat first RTx appears very important. Long-term administration of prednisone on alternate days would then result in optimal FH, particularly if the GFR remains above 50 mL/min/1.73 m2.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Casein-predominant infant milk formulas have been speculated to predispose to lactobezoar formation in preterm infants due to delayed gastric emptying. There have been, however, no prospective studies to prove this possi-bility. In a randomized, double-blinded, prospective study, we tested the hypothesis that preterm infants fed casein-predominant milk formula have slower gastric emptying than infants fed whey-predominant formulas. Twenty pre-term infants within the first 4 d of life were randomized to receive either the whey-predominant formula Similac Special Care (whey:casein ratio 60:40) or an experimental casein-predominant formula (whey:casein ratio 18:82). Only the protein composition differed between the two formulas. The infants were fed the assigned study formula until they reached approximately 2200 g body weight when a gastric emptying scan was performed, using the designated study formula mixed with 25 μCi of technetium-99 sulfur colloid. Gastric emptying was followed continuously for 2 h. Gastric emptying at 30, 60, 90, and 120 min was similar between the two study groups. The time for 50% gastric emptying was 64.9 ± 12.3 min for the infants fed the whey-predominant formula and 56.5 ± 14.8 min for those fed the casein-predominant formula (p= 0.75). We conclude that the rate of gastric emptying in preterm infants fed casein-predominant formulas is similar to that in those fed whey-predominant formulas.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID