摘要:

Red cell glycolytic intermediates and ATP were evaluated in 47 appropriate for gestational age preterm infants on the 1st day of life who were divided into three groups on the basis of gestational age: 28-30, 31- 33, and 34-36 wk. The results were compared to those previously obtained in term infants. The concentrations of glucose-6-phosphate, total triose phosphates, and ATP were significantly higher than in term infants but appeared to be appropriately elevated for the young mean age of the red cell population. The concentration of red cell 2,3- diphosphoglycerate (2,3-DPG) was significantly decreased when compared to term infants and was lowest at 28-30 wk gestation. The content of red cell 3-phosphoglycerate was increased in term infants and was inappropriately elevated for the age of the red cell population at 28-30 wk gestation. This pattern of glycolytic intermediates was suggestive of a young red cell population metabolizing at an increased glycolytic rate with increased flow through the phosphoglycerate kinase step rather than the 2,3-DPG bypass in “normal” preterm infants. Two preterm infants of 28-30 wk gestation with low red cell intracellular pH were also evaluated and had markedly decreased concentrations of red cell 2,3-DPG and ATP and all phosphorylated intermediates distal to the phosphofructokinase reaction, indicative of a cross-over at the phosphofructokinase step secondary to acidosis. These studies demonstrate that the “normal” preterm infant has a decreased concentration of red cell 2,3-DPG in the steady state and in the presence of acidosis additional red cell metabolic perturbations occur which lead to a further fall in red cell 2,3- DPG and a decrease in the concentration of red cell ATP.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Simultaneous colostrum (C) and plasma samples (P) from 14 women, 1 to 5 days postpartum, were examined. Total IgD and specific IgD antibodies to β- lactoglobulin, bovine serum albumin, Bermuda grass, and a-gliadin were measured by solid phase radioimmunoassay. The geometric mean concentrations of IgD were 35.8 (range 2.2-410) µg/dl for colostrum and 591.3 (range 72- 4100) µg/dl for plasma. Six subjects had a specific IgD antibody C/P ratio more than 10-fold greater than the total IgD C/P ratio, suggesting enhancement of antibody to a specific antigen in the mammary gland. All six had C/P ratios suggestive of local enhancement of IgD antibody to Bermuda grass, and two met this criterion for enhancement of IgD antibodies to β-lactoglobulin, bovine serum albumin, or a-gliadin. Specimens for these studies were obtained during the peak grass pollen season. Seventeen additional subjects were studied to compare total IgD in colostrum and plasma with total IgG and serum albumin. The mean C/P ratio for IgD (0.055 ± 0.015) exceeded the C/P ratio for total IgG (0.015 ± 0.003) or total albumin (0.020 ± 0.002). For 14 of 17 subjects the colostrum/plasma ratio for IgD exceeded the C/P ratio for albumin or IgG. Data were transformed logarithmically and correlation coefficients calculated. For albumin versus IgG in colostrum, there was a strong correlation, r = 0.865, p = 0.001. This was different from albumin versus IgD, r = 0.489, p = 0.046 and from IgD versus IgG, r = 0.556, p = 0.020. These analyses support a different mechanism of entry of IgD into milk compared to IgG or albumin. These studies also suggest that IgD antibodies may participate in responses of the mucosal immune system.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Newborn rabbits were overfed by encouraging them to suckle from two lactating does. Rabbits fed in this way (double fed) were compared with littermate controls (single fed) at age 7,14, and 21 days. The double-fed rabbits gained weight more rapidly and at each age contained a higher percentage of fat than their single-fed counterparts. During the 1st wk the double fed rabbits stored some of their extra fat in the cervical and interscapular adipose lobes. Double-fed rabbits utilized their feeds more efficiently than single fed rabbits in that they gained more weight per unit milk intake and their gross energetic efficiency was 10-20% higher. In a second series of experiments oxygen consumption rate was measured in singleand double-fed rabbits at ages 7,14, 21, and 28 days. The relation between oxygen consumption and body weight were similar. We conclude that rabbits respond to overfeeding with an increased rate of weight gain associated with extra fat deposition, and this is associated with increased energy efficiency.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To explain the reported predisposition to germinal matrix hemorrhage in premature infants, pathogenetically important morphological features of the germinal matrix should be present in the 3rd trimester and rapidly change near term. Such features were sought in this study of the germinal matrix and its vasculature in normal rhesus monkey fetuses. The matrix cells, glia, ependyma, and capillaries showed no important structural changes during the 3rd trimester. The terminal vein tributaries were greatly enlarged by 148 days, but cellular and collagen support in their walls was minimal at this time. The latter features developed by the final days of gestation. These findings do not support a structural immaturity or specialization of the germinal matrix predisposing to germinal matrix hemorrhage. Our results, therefore, support the recent emphasis on physiological parameters in the pathogenesis and prevention of germinal matrix hemorrhage.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Sucrase-isomaltase complex is expressed in human small intestine throughout gestation and in the large intestine between 12 and 30 wk. The molecular form of the enzyme was studied in the brush-border membrane fractions by the immunoblotting method. Before 30 wk of gestation, the enzyme is present only as the high molecular weight prosucrase-isomaltase, while from 30 wk until birth the two subunits are also present. The fetal enzyme, as its proform and as its two subunits, has a faster mobility in sodium-dodecylsulfate polyacrylamide gel electrophoresis, than the adult enzyme (removal of sialic acid residues from fetal enzymes emphasizes this difference). The colonic and the small intestinal fetal enzymes are identical.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The objective of this study was to characterize the fatty acid biosynthetic pathway of the lactating human breast. Mixed cell populations, obtained by centrifugation of human milk, were enriched in breast epithelial cells by a selective adsorption procedure. Confirmation of the identity of the breast epithelial cells was obtained immunohistochemically. These viable breast epithelial cells incorporated radioactively labeled acetate predominantly into fatty acids with less than 16C atoms. The presence of the two key enzymes characteristic of the medium-chain fatty acid biosynthetic pathway of nonruminants, fatty acid synthetase, and thioesterase II, was demonstrated both qualitatively, by immunohistochemistry, and quantitatively, by enzyme assay. The results indicate that the lipogenic system of the human breast is qualitatively very similar to that of rats, mice, and rabbits, which also secrete milk fats containing medium-chain fatty acids. Quantitatively, however, the mammary fatty acid biosynthetic pathway appears to be less active in humans than in these other species.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Premature rabbit neonates delivered at gestational age 27 days were ventilated by high frequency oscillation for 60 min with 100% O2, using a frequency of 7-8 Hz, 50% inspiration time and mean airway pressures of 6-8 cm H2O. Twenty-five animals received bovine surfactant (2 ml/kg body weight; phospholipid concentration 85-100 mg/ml) in the tracheal cannula before onset of ventilation, and 22 littermates served as controls. In the surfactant-treated group, average tidal volume was about 10 times larger than in controls, yet only 15% of the estimated dead space. Judged from ECG recordings, the treated animals also had a much higher survival rate: 96 versus 5% (p<0.001). Morphometrically, mean alveolar volume density was increased in the surfactant-treated animals in comparison with controls: 0.65 ± 0.08 versus 0.37 ± 0.08 (x ± SD;p<0.005). Bronchiolar epithelial lesions were found in all control animals and were severe in almost all cases. In the surfactant-treated group, epithelial lesions were absent in 12, mild in 11, and fairly prominent in two animals. We conclude that after treatment with surfactant, the premature newborn rabbit can be ventilated adequately with high frequency oscillation at comparatively low mean airway pressures and that surfactant replacement effectively reduces the development of epithelial lesions in conducting airways during high frequency oscillation.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Rheological parameters were measured in 10 pairs of mothers and newborns. Whole blood viscosity was similar despite a higher fetal hematocrit (47.0 ± 5.1 versus 35.5 ± 12.0%, mean ± SD,p<0.05). When the hematocrit of the suspension of red cells in plasma was adjusted to 45%, the viscosity was significantly lower in the fetal blood over a wide range of shear rates (0.52-208 s-1). The main reason for the lower viscosity in the fetal blood was the lower plasma viscosity as compared to the maternal blood (1.08 ± 0.05 versus 1.37 ± 0.08 centipoise,p<0.05); this in turn was attributable to a lower total plasma protein concentration (4.74 ± 0.71 versus 6.47 ± 0.64 g/dl,p<0.05). All protein fractions were lower in the fetal plasma. The assessment of red cell deformability by filtration through polycarbonate sieves revealed that the resistance of a fetal red cell was three times higher than that of a maternal red cell in a 2.6-μm pore, but there was no significant difference in resistance for these red cells in 6.9-μm pores. This higher filtration resistance of fetal red cells through the small pores was mainly due to their large volume (115.4 ± 10.8 versus 93.5 ± 5.9 fl,p<0.001). Measurements on membrane-free hemoglobin solutions indicated that the internal viscosity of these two types of red cells was not different. We conclude that in fetal blood the higher hematocrit and the presence of larger red cells, which cause impaired passage through pores <5 μm, are counterbalanced by a decreased plasma viscosity, resulting in a whole blood viscosity comparable to that of adults.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Acid sphingomyelinase activity was determined in Epstein-Barr virus-transformed lymphoid cell lines (LCL) established from patients affected with Niemann- Pick disease (NPD) using several substrates: sphingomyelin derivatives, radiolabeled [14C]sphingomyelin (SM), fluorescent 7V-(10-(l-pyrene)decanoyl)sphingomyelin (P10-SM) or colored trinitrophenylaminolaurylsphingomyelin, and the chromogenic non-natural substrate 2-/V-(hexadecanoyl)amino-4-nitrophenylphosphoryl-choline. LCL from NPD Type A and Type B showed a severe deficiency of acid sphingomyelinase determined using either substrate, whereas LCL from normal subjects had an activity close to that of blood leukocytes. Sphingomyelinase in normal LCL had the same pH optimum (5.0-5.2) and molecular form (pi 5.8) as the enzyme from other sources; identical profiles and activity levels were obtained using the various analogues of sphingomyelin. However, among these derivatives, the assay using P10-SM appeared as the most useful and sensitive for enzymatic diagnosis of NPD. Electron microscopy of NPD LCL demonstrated the lysosomal storage. These results prove the validity of LCL as an experimental model system for NPD.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID