摘要:

We studied the effect on the circulation of reducing peripheral vascular resistance by infusing sodium nitroprusside into lambs of three different age groups (subgroup A, 11-26 days, subgroup B, 32-52 days, and subgroup C, 61-88 days of age) with and without an aortopulmonary left to right shunt. Infusion of 10 μg/kg/ min nitroprusside over 2 h decreased aortic and left atrial pressures markedly and increased heart rate, whereas systemic, pulmonary, and left to right shunt blood flows hardly changed. Within 30 min after the onset of infusion, the hemodynamic variables stabilized. Aortic and left atrial pressures were still below control levels at that time. The different flows remained the same and heart rate, after an initial fall, increased again. The pattern of hemodynamic changes was not influenced by age or the presence of an aortopulmonary left to right shunt. Based on this study, we do not advocate sodium nitroprusside administration in case of a left to right shunt with normal arterial pressure and systemic blood flow

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Mucin levels are generally elevated in sera from many cystic fibrosis (CF) patients as measured by radioimmunoassay using monoclonal antibody 19-9, which is directed against the mucin-associated sialyl Leaantigen. Antibody 19-9 can only be used to measure mucin-associated antigen levels in those patients who are genetically able to make detectable levels of mucin-associated sialyl Lea<0.025). Serum mucinassociated antigen levels of CF patients who were colonized with Pseudomonas aeruginosa did not significantly differ from those of uninfected CF patients. The mean serum mucin-associated antigen level of CF patients colonized with Pseudomonas was higher than the mean mucin level of six non-CF bronchiectatic patients whose lungs were colonized with Pseudomonas (p=0.053). Serum mucinassociated antigen levels are thus related to CF patients' ages and clinical statuses

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

We investigated the role of lipid peroxidation as the mechanism mediating copper toxicity in isolated rat hepatocytes and the modulating effect of vitamin E. Hepatocytes, isolated from rats fed diets containing deficient (E—), sufficient (E+), and excess (E++) amounts of vitamin E, were incubated with CuCl2(0-2400 μM) for 150 min. Dose and time-dependent decreases in hepatocyte viability (determined by trypan blue exclusion and lactate dehydrogenase release) due to copper toxicity correlated with production of malonyldialdehyde in E - and E+ hepatocytes. However, malonyldialdehyde generation did not accompany copper toxicity in E++ cells. Copper toxicity was enhanced in E— compared to E+ and E++ hepatocytes as assessed by cell viability studies and ultrastructural plasma membrane bleb formation. In vitro vitamin E repletion of E— hepatocytes restored resistance to copper and decreased malonyldialdehyde production proportionately. Thus vitamin E deficiency appeared to increase the susceptibility of hepatocytes to copper toxicity. We conclude that lipid peroxidation may not be the mechanism by which copper is toxic to isolated hepatocytes but that the site of injury may be thiol-rich cellular proteins

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

We studied the effects of a diet that was low in fat, high in carbohydrate (CHO) on milk lipid composition and de novo endogenous fatty acid synthesis by the mammary gland in five lactating women. The women consumed either a low fat (LF) (5% fat, 80% CHO) diet or a high fat (HF) (40% fat, 45% CHO) diet. Fat synthesis was determined after an oral dose of 500 mg/kg D2O by measuring the incorporation of deuterium into C10:0 to C18:0 saturated fatty acids of milk fat and plasma triglycerides by gas chromatography-mass spectrometry. Synthesis of plasma C16:0 and C18:0 triglycerides was barely detectable while women consumed the HF diet, but was increased 6-fold during the LF diet. Medium chain fatty acids secreted by the mammary gland increased from 12.8% (HF diet) to 16.3% (LF diet) in milk fat from four of five subjects (p=0.027). Medium chain fatty acid secretion, however, increased from 13.9% (HF diet) to 29.9% (LF diet) in one subject. The primary fatty acids synthesized during lactation were C10:0, C12:0, and C14:0 in the majority of women studied. The LF diet significantly increased the apparent synthesis of C14:0 (p=0.05), whereas no changes were observed in C12:0, C16:0, or C18:0. One subject had highly enriched C16:0 and C18:0 fatty acids in her milk on the LF diet, which could have been the result of mammary synthesis or of transport and secretion of hepatically synthesized lipids

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

To find a better treatment for patent ductus arteriosus of preterm infants, we studied the combined effect of indomethacin and betamethasone on the fetal ductus in rats. We used a rapid whole-body freezing technique, and the ratio of the inner diameter of the ductus to the main pulmonary artery, which was 1.0 in controls, was used as an index of constriction. Indices of ductal constriction 4 h after administration of indomethacin (1 mg/kg) alone, betamethasone (1 mg/kg) alone or in combination in near-term rats were 0.56 ± 0.05 (mean ± SEM), 0.76 ± 0.06, and 0.17 ± 0.03, respectively. In preterm rats too, a marked increase in fetal ductus constriction was observed with the combined administration of these two drugs. Study of the dose effect of betamethasone revealed that maximal effects were obtained with 1 mg/kg of betamethasone combined with indomethacin in both preterm and near-term fetal rats. Increased constriction of the fetal ductus with combination treatment persisted from 1 to 8 h after administration. Administration of betamethasone 24 h before the rat was killed did not augment constriction of the fetal ductus by indomethacin administered 4 h before they were killed. Fetal ductus constriction by sulindac, another nonsteroidal antiinflammatory drug with little inhibitory effect on renal function, also was augmented by combined use with betamethasone (1 mg/kg). In conclusion, ductal constriction was markedly increased by combined administration of indomethacin and betamethasone in near-term and preterm fetal rats

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

To determine whether growth hormone has a direct effect on skeletal tissues not mediated by somatomedins, and to better define the role of somatomedin-C/ insulin-like growth factor I (Sm-C/IGF-I) in skeletal development, bovine growth plate, and rabbit articular and growth plate chondrocytes in primary culture were evaluated under a variety of experimental conditions designed to elicit growth hormone and Sm-C/IGF-I stimulation. Under none of these conditions did bovine growth plate chondrocytes respond to either homologous bovine growth hormone or heterologous hGH. Under the same conditions, these cells were highly responsive to human Sm-C/IGF-I with respect to both [3H]thymidine and [35S]sulfate incorporation, indices of mitotic and differentiated cell functions, respectively. Similarly, both rabbit articular and growth plate chondrocytes showed enhanced incorporation of [3H] thymidine and [35SJsulfate in the presence of Sm-C/IGF-I, but did not respond to either native or recombinant hGH. Cells at different stages of maturation within the bovine growth plate differed in their reaction to Sm-C/IGF-I with proliferative zone cells manifesting a greater response to the peptide than cells of the reserve zone. These results suggest that the action of Sm-C/IGF-I on growth plate and articular chondrocytes is direct and that the effect of GH on these cells is indirect. The data further suggest that within the growth plate, the transition from reserve to proliferative status is associated with an increased Sm-C/ IGF-I responsiveness, a change which may contribute to the functional differences in these cells

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

We studied the effect on surfactant metabolism of 8 h of mechanical ventilation at tidal volumes of 13 ± 0.3 ml/kg and very high tidal volumes of 28 ± 1.5 ml/kg, with and without added CO2, in the presence of an atrial right to left shunt in 4- to 8-day-old lambs. Similarly aged, spontaneously breathing lambs were used as controls. Right to left atrial shunts were created by inflating a balloon in the right atrium after a Rashkind atrial septostomy, thus creating a stable, easily controlled atrial shunt. Radiolabeled surfactant phospholipid precursors were used to probe incorporation into and secretion of surfactant phosphatidylcholine, whereas intratracheally administered labeled natural surfactant was used to evaluate alveolar clearance. Protein leak from the vascular space to the lungs was measured using radioactive iodine-labeled albumins. At the end of the 8-h study period, tissue association of alveolar surfactant was significantly increased to 63% in the mechanically hyperventilated lambs as compared to 44% in those lambs mechanically ventilated but not hyperventilated (p<0.05) and to 39% in the spontaneously breathing control animals (p<0.05). No increased surfactant secretion or decreased compliance was detected with hyperventilation. However, the lambs had very large surfactant- saturated phosphatidylcholine pool sizes, and a large portion (50%) was already in the alveolar pool, even in the spontaneously breathing lambs. Precursor incorporation into saturated phosphatidylcholine was similar in all groups, and very low and comparable protein leaks were seen in the different groups of lambs. These experiments did not detect any adverse effects of 8 h of mechanical ventilation, large atrial shunts or mechanical hyperventilation on the surfactant system of newborn lambs

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

A girl aged 12 y, 9 mo, suffered from a progressive neurodegenerative disorder marked by ataxia, extrapyramidal symptoms, and convulsions. A skin biopsy showed axonal pathology that emphasized axonal segments enlarged by mitochondria, dense bodies, and lysosomal residual bodies of the membranous cytoplasmic body type. This ultrastructural pathology suggested GM2gangliosidosis which was shown to be a Bivariant by specific biochemical studies, although conventional techniques had failed to detect GM2gangliosidosis. The Bivariant is marked by a deficient activity of β-hexosaminidase A towards one substrate, and by an almost normal activity towards another. Both parents showed a diminished activity towards the sulfated substrate, suggesting a heterozygous state, and almost normal activity with the second substrate type

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

The vessel wall properties of the common carotid artery were noninvasively studied in 53 normotensive, presumed normal boys of various ages (4-19 yr) with the use of a multigate pulsed Doppler system. This device allows the on-line recording of velocity profiles and the relative changes in carotid artery diameter during the cardiac cycle. From the width of these profiles, the internal diameter of the carotid artery can be determined. With the use of internal carotid artery diameter, relative changes in carotid artery diameter during the cardiac cycle, and pulse pressure the pulse pressure, as measured in the brachial artery, the distensibility coefficient and the cross-sectional compliance were calculated. The children were allotted to three different age groups: group I (4-10 yr), group II (11- 14 yr), and group III (15-19 yr). In the older children (group III) the systolic arterial pressure and the pulse pressure were significantly higher than in groups I and II. The carotid artery diameter was significantly larger and the distensibility coefficient was significantly smaller in group III than in groups I and II. The cross-sectional compliance was not significantly different in the age groups, which can be explained by the larger artery diameter in the older age group. The findings indicate that the carotid artery wall is less distensible in adolescents than in younger children. The subjects in group III showed similar carotid artery wall properties as the young adults (aged 20-34 yr) in a previous study. Therefore, it is likely that in adolescents the vascular system can be considered as mature as far as the arterial wall properties are concerned

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

To investigate mechanisms of ATP depletion in human umbilical vein endothelial cells after oxidant injury, we studied the relationship between DNA damage, activation of the DNA-repairing enzyme poly ADP-ribose polymerase, NAD depletion, and ATP depletion. We found that oxidant stress generated with hypoxanthine-xanthine oxidase and glucose-glucose oxidase resulted in profound DNA damage. When endothelial cells were exposed to 25 and 50 mU/ml xanthine oxidase for 60 min, the percentage of double-stranded DNA was significantly reduced (p<0.05) to 15.2 ± 1.2 and 4.6 ± 0.5%, respectively, compared to 75.7 ± 3.9% for control cells. When endothelial cells were exposed to 25 and 50 mU/ml glucose oxidase for 60 min, the percentage of double-stranded DNA was significantly (p<0.05) reduced to 35.0 ± 1.5% and 9.9 ± 7.7%, respectively, compared to 73.2 ± 2.4% for control cells. ATP and NAD levels declined simultaneously with DNA damage. Because activation of the DNA-repairing enzyme poly ADP-ribose polymerase can consume NAD sufficient to interfere with ATP synthesis, we studied NAD and ATP levels after oxidant injury when ADP-ribose polymerase was inhibited with 3-aminobenzamide and nicotinamide. When poly ADP-ribose polymerase was inhibited, NAD levels remained normal, but ATP depletion was not prevented. We conclude that oxidant injury to human umbilical vein endothelial cells results in profound DNA damage and NAD and ATP depletion. NAD depletion results from activation of poly ADP-ribose polymerase, but this phenomenon is not the mechanism of ATP depletion in human umbilical vein endothelial cells

ISSN:0031-3998    

出版商:OVID    

年代:1989

数据来源: OVID