摘要:

Sulfhydryl oxidase (SOX) is present in human milk and in milk from all species that have been studied. The pH optimum of human milk SOX is in the neutral range between 7.0 and 7.5. Human milk SOX is stable in an acid environment: 50% of its activity remains after 1 h at pH 2.5. Acid stability is also characteristic of y-glutamyltranspeptidase, another membrane-bound enzyme in skim milk. SOX is resistant to pepsin (4000 U/ml), trypsin (50 μg/ml), chymotrypsin (200 μg/ml), and to trypsin plus chymotrypsin (25 μg each/ml). Milk SOX activity has been detected in the stomach and proximal small intestine contents of suckling rats. Human and bovine SOX are relatively heat stable: 75% of the latter remains after treatment at 62.5°C for 30 rnin and 65% of the former remains after treatment at 607°C for 10 min. Neither remains after 62.5°C for 30 min.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Exposure of circulating rabbit granulocytes to the chemoat-tractant N-formyl-methionyl-leucyl-phenylalanine (FMLP) in vivo results in transient granulocytopenia, hypotension, and car-diorespiratory distress. The effectiveness of vitamin E in attenuating these responses was tested. Vitamin E accelerated the rate of return of granulocytes to the peripheral circulation after FMLP-induced granulocytopeniaand mitigated the hypotension. The reversible adherence of FMLP-stimulated granulocytes to endothelium offers a plausible mechanism to explain the transient granulocytopenia.From in vitro studies it was found that FMLP-activated granulocytes from animals treated with vitamin E showed decreased adherence to cultivated aortic endothelial monolayers when compared with FMLP-activated granulocytes from control animals.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We have previously described the purification and partial characterization of a serum glycopeptide with mucociliary activity from cystic fibrosis patients and a normal counterpart from sera of controls (3,4). After removal of its oligosaccharide component by β-elimination, the peptide portion of the glycopeptide from cystic fibrosis patients did not reveal any mucociliary activity on rabbit tracheal explants. This mucociliary activity was shown to be inhibited by mannose, glucose, and N-acetyl-galactosamine as well as by the glycopeptide purified from controls. It was not affected by xylose, fucose, galactose, or N-acetyl-glucosamine.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We describe an assay for acetyl-CoA: a-glucosaminide N-acetyltransferase using purified [14C]glucosamine as substrate, and leukocytes as enzyme source. The assay is suitable for the diagnosis of homozygous and heterozygous carriers of Sanfilippo syndrome type C.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The present study employed an animal model in an attempt to document effects on brain growth of long-term exposure to the ophylline in the presence or absence of malnutrition.One group of dams was randomly divided into half. One-half was fed a 20% protein diet and the other half a 6% protein diet. Similarly, a second group of dams was also randomly divided into two groups. These were pair-fed with rats of the first group, receiving diets comparable to those in group one but to which theophylline was added in amounts calculated to provide daily doses of 2 μg/100 g of body weight. Theophylline supplementation in the dams' 6% protein diet decreased the body weight of the pups consistently from d 3 to the end of the study at d 15 in comparison to the non-theophylline group. In contrast, the pres- ence of theophylline in the control diet increased the body weight of the pups at d 15 compared with that of the non-theophylline group. Brain weight was essentially identical in the normal controls and the normally nourished group given theophylline. No difference in brain weight was noted between the malnour- ished group and the malnourished group given theophylline.We found a significant reduction in DNA content per brain or per mg of brain weight in the normally nourished group given theophylline compared with non-theophylline group. DNA values per mg of brain weight from the controls that received theophylline were not different from either malnourished group. RNA, expressed as μg RNA per mg brain weight, was significantly reduced in the normally nourished group that received theophylline when compared with the normally nourished controls and the malnourished group that received theophylline.Total protein content per brain was significantly reduced in the malnourished group that received theophylline compared with non-theophylline group. A significant increase in the amount of protein in the malnourished groups as opposed to the normally nourished groups was measured (μg protein per mg brain).The brain cell size (protein:DNA) calculated by the standard method in the malnourished group supplemented with theophylline was smaller compared with that of the non-theophylline group, but cell size in the control group given theophylline was greater. It appears that theophylline supplementation in the maternal diet affects the cell size differently according to the nutritonal state of the offspring.Our data suggest that, in the animal model, the administration of theophylline in the presence of a compromised nutritional status may have effects not now apparent. We add our concern to that expressed by others that methylxanthine administration may have previously unsuspected effects on the developing brain.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Hypoxia is a potent stimulus to the release of vasopressin in fetal sheep and, in turn, plasma concentrations of the hormone correlate inversely with fetal oxygenation. Because the fetal kidney contributes to vasopressin clearance, we propose that measurement of increased amounts of vasopressin in amniotic fluid would be indicative of fetal hypoxia. We therefore measured concentrations of vasopressin in amniotic fluid under resting conditions, during and after fetal hypoxia, and with intravenous and intra-amniotic administration of vasopressin in 15 chronically instrumented fetal lambs 111–141 d gestation. In the resting state mean (±SE) vasopressin concentrations in amniotic fluid (1.6 ± 0.3 pg·ml-1) did not differ from those in maternal (1.4 ± 0.4 pg·ml-1) or fetal (1.8 ± 0.2 pg·ml-1) plasma. After exposure of the ewe to 10% O2or partial occlusion of the umbilical cord, vasopressin concentrations in fetal plasma increased significantly (P < 0.001) to 200 ± 59 pg.ml-1with a delayed increase in amniotic fluid concentrations (P < 0.03) to 15.8 ± 4.5 pg.ml-1. This rise in concentration of vasopressin in amniotic fluid was sustained for at least 24 h and levels at that time were highly correlated with peak plasma concentrations (r = 0.83, P < 0.001). Intravenous infusion of vasopressin into the fetus was accompanied by an equally significant (P < 0.02) and sustained increase of vasopressin in amniotic fluid. After intraamniotic injection of vasopressin, levels remained increased for at least 24 h.In the third trimester of ovine gestation amniotic fluid vasopressin concentration was a reliable indicator of prior fetal hypoxia. Parallel amounts of antidiuretic activity measured by bioassay and vasopressin by radioimmunoassay confirmed the presence of active hormone in amniotic fluid. Hypoxia alone was not a stimulus to passage of meconium and increased concentrations of vasopressin in fetal plasma were not associated with expulsion of meconium in utero. Despite elevated concentrations of vasopressin in amniotic fluid, no associated changes in intra-uterine pressure were discerned.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

To gain insight into the mechanisms responsible for the impaired glycogenolytic response to glucagon and the diminished ketogenic capacity of newborn guinea pig, we studied the ontogeny of insulin and glucagon receptors, and the responsiveness of the adenylate cyclase complex to glucagon, PGE1NaF, and cholera toxin in liver plasma membrane from fetal (58 d, late gestation, and 65 d, term) and adult guinea pigs. The number of insulin receptors (7×10-1M/L) was least in 58-d fetus (3.0 ± 0.4; mean ± SEM) and increased 3-fold in 65 d fetus (8.8 ± 0.6; P < 0.01). In adult guinea pig, both insulin receptor number (6.0 ± 0.7) and average affinity constant (1.20 ± 0.08 × 108M-1) were significantly lower (P < 0.01) compared with 65-d fetus. The number of glucagon receptors remained unchanged between 58-d and 65-d fetuses, but both average and high affinity association constants were significantly higher at d 65. In contrast to the lower capacity and affinity of insulin receptors in the adult compared with term fetus, the total glucagon receptor number (×10-10M/L) in adults (7.2 ± 0.8) was twice that of the 58 d (3.2 ± 0.2) and 65 d (3.2 ± 1.0) fetuses. The average affinity constant (×108M-1) in adult (3.8 ± 0.2) was, however, significantly lower than the two fetal groups (58 d, 5.0 ± 0.3; P < 0.05 and 65 d, 8.1 ± 1.0; P < 0.05). Although the total glucagon receptor number at d 58 was approximately 50% of that present in the adult, glucagon did not stimulate cAMP production above basal; all other stimuli evoked significant increases. By 65 d, the fetal membranes responded to glucagon as well as to all other agents with appropriate cAMP production. In the presence of 0.5 mM guanosine-5'-triphosphate, the cAMP response to prostaglandin El was similar in all three groups. These results demonstrate the following in liver plasma membrane from the guinea pig. 1) At term, insulin receptor numbers are higher than in less mature fetus or in adult. 2) There is a delay in maturation of functional glucagon receptors coupled to the adenylate cyclase complex. 3) Apart from failure of response to glucagon, the adenylate cyclase complex is otherwise functionally mature even at 58 d because it responds to PGE, and other agents.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The absorption of liquid volume and radiolabeled tracer solutes from the lungs of premature lambs was investigated during the first hours of ventilation. Exteriorized lambs, 133–141 d gestation, with intact umbilical circulation had [131I]albumin and [125I] cytochrome C added to the fetal lung liquid before breathing, and, additionally, [57Co]cyanocobalamin added to the remaining alveolar liquid after 20, 60, and 120 rnin of ventilation. Alveolar liquid was rapidly absorbed from the alveolar space, averaging more than 75% absorption in the first hour whether they breathed spontaneously or were ventilated. All animals absorbed proteins and water at the same rate as water during the first 20 rnin of breathing. Older, spontaneously breathing lambs released more surfactant into the alveolar space (302 ± 82 pM) than younger ventilated animals (92 ± 32 pM). After the first 20 rnin of breathing, older animals no longer absorbed [131I]albumin and [125I]cytochrome C, and at 4 h had near normal lung wet:dry weight ratio, 5.7 ± 0.2. Younger animals continued to absorb [131I]albumin and [125I]cytochrome C as rapidly or more rapidly than liquid, and after 4 h had retained liquid in the lung wet:dry weight ratio 6.3 ± 0.2. Alveolar surfactant appears able to alter the solute permeability of ventilated premature lung and the clearance of the fetal liquid from the lungs.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID