摘要:

The cardiac, pulmonary vascular, and systemic vascular effects of bolus injections (2.5, 25, 50 µg/ kg) and 5-min infusions of 50 µg/kg/min of Nifedipine were tested in conscious, chronically instrumented newborn lambs. While breathing room air, bolus injections of 50 µg/kg into the pulmonary artery caused the cardiac index and left ventricular dp/dt to fall as did systemic arterial pressure and calculated resistance (all changes significantp<0.05). Pulmonary artery, pulmonary vein, and left atrial pressure all tended to increase and there was a shift in flow away from the injected lung (14 ± 0.05%). Pulmonary arteriolar resistance in the injected lung increased significantly (p<0.05). Nifedipine failed to prevent hypoxia- induced pulmonary vasoconstriction, and when given during hypoxia, caused a further rise in pulmonary artery pressure with a marked fall in left ventricular dp/dt and systemic vascular resistance. These acute effects peaked 30 s to 2 min after injection and all hemodynamic variables returned to baseline by 10 min. Five-min infusions caused similar effects which completely reversed 20 min after the infusion was stopped. Nifedipine causes significant cardiac depression combined with systemic vasodilatation and pulmonary arteriolar constriction in conscious newborn lambs. Assuming similar actions in humans, it seems quite unsuitable for the therapy of pulmonary hypertensive problems of newborn infants.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Ten children with end stage renal disease on chronic hemofiltration (HF) were studied for a 1-yr period to evaluate the efficacy of l,25-dihydroxyvitamin-D3(1,25(OH)2D3) therapy on biohumoral parameters of renal osteodystrophy and bone mineral content. In six of these children an acute study was done of the direct effect of the HF procedure on calcium and phosphate balance during 12 HF sessions. During the first 6 months of the study all children were treated with 1,25(OH)2D3(0.25-0.50 µg/day) to maintain plasma calcium at 9.5-11.0 mg/dl. There was a significant increase in plasma calcium (p<0.05) and a significant decrease in plasma phosphate (p<0.01) and alkaline phosphatase concentrations (p<0.05). The circulating levels of NH2immunoreactive parathyroid hormone did not change, remaining at the upper limits of reference values. Immunoreactive parathyroid hormone- COOH terminal fragment levels decreased significantly (p<0.05). Bone mineral content rose significantly (p<0.01). During the last 6 months of the study, to evaluate the possibility that HF alone might control secondary hyperparathyroidism, 1,25(OH)2D3treatment was discontinued in five children; plasma calcium and phosphate were well controlled whereas hyperparathyroidism worsened in all five, and one also developed intense pruritus and hypertension. The other five children remained on 1,25(OH)2D3treatment; two of these were transplanted, and the other three continued to show an improvement of mineral balance. The results of the acute study showed that calcium balance was positive with a mean Ca++gain of 140 mg/HF session. The mean total phosphate removed per HF run was 574 mg. We conclude that even though a calcium gain and a high phosphate removal was obtained with our HF prescription, secondary hyperparathyroidism in children on chronic HF may be maintainued under control if 1,25(OH)2D3supplementation is provided.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effect of Cis-platin on the glomerular filtration rate and effective renal plasma flow was determined using a radioisotope clearance technique in young (3 wk old) and adult (more than 12 wk old) rats. Cis-platin was administered intravenously in dosages ranging from 2.5 to 10 mg/kg body weight, either as a single dose or fractionated over 5 consecutive days. Following either dose regimen, identical total doses of Cis-platin caused less severe nephrotoxicity in young rats than in adult ones. In adult rats fractionated dosage significantly reduced nephrotoxicity. This was not observed in young rats. The difference in nephrotoxicity between young and adult rats was due to the renal handling of Cis-platin. After a single dose of 5 and 7.5 mg/kg body weight, platinum concentrations were measured in urine and renal tissue. During the first 2 days after Cis-platin administration, up to 60% of the amount of platinum injected was excreted in the urine of both age groups. There was a marked difference, however, in renal platinum concentration between the two groups. In young rats renal platinum concentration was only 63 and 49% of that in adult rats after 5 and 7.5 mg/kg body weight, respectively. We believe that this is due to the comparatively larger renal mass in relation to body weight in the young animals. Relatively more renal tissue provides at least partial protection against nephrotoxic drugs in these young rats.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Acute hypoxemia was produced in chronically catheterized sheep fetuses to determine the response time necessary to increase plasma immunoreactive erythropoietin (Ep) concentration. Sodium nitrite (0.2 mM) was infused via a fetal vein to induce fetal hypoxemia. The resultant fetal methemoglobinemia was associated with a predictable, incremental decrease in arterial oxygen content. Twelve nitrite infusions were performed in eight fetal sheep preparations (gestational ages 115-146 days). Mean methemoglobin level increased to 33% of total Hb after 1- 2 h of NaNO2infusion. These results were compared to those obtained in nine control studies in eight fetuses in which no change was observed for plasma Ep, arterial oxygen content, Pao2, pHa, or whole blood lactate. In the nitrite infused group, however, a significant and progressive increase in mean plasma Ep level over baseline levels was observed during the 4th and 5th h of hypoxemia (p<0.01). This change in Ep was significantly greater compared to the control group. These results, however, were confounded by the concomitant development of a lactic acidemia secondary to the fetal hypoxemia. To examine the theoretic possibility that lactic acidemia may primarily affect fetal Ep levels, an additional group of five fetuses was infused with L-lactic acid for the same time period. Although the decrements in pHaand whole blood lactate levels achieved in these fetuses were in excess of those observed during the nitrite infusions, this possibility was ruled out since no change in fetal plasma Ep levels occurred. We conclude that during the 4th h of acute fetal hypoxemia a predictable, progressive increase in plasma Ep level is observed. This response of plasma Ep to hypoxemia in late gestation fetal sheep is qualitatively similar to that observed in adult animals, thus demonstrating developmental maturity of the fetus.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Our previous cross-sectional study of patients with thalassemia major suggested progressive lung changes characterized by low total lung capacity, hypoxemia, and elevated transfer factor for carbon monoxide. We reevaluated nine of the patients for three reasons: 1) to determine the relationship of the previous findings to the immediate effects of blood transfusion; 2) to assess the longitudinal progression of the lung changes; and 3) to evaluate the effect of splenectomy on lung volume changes in these patients, all of whom underwent splenectomy in the interval between the two studies. We found that during the 5- to 6-yr period between studies total lung capacity had decreased significantly (p<0.05) from a mean 86% predicted to a mean 79% predicted. However, vital capacity increased significantly (p<0.05) from a mean 81% predicted to 88% with no significant change in functional residual capacity. There was no significant immediate effect of transfusion on total lung capacity, vital capacity, or functional residual capacity. However, the diffusion constant for carbon monoxide increased significantly (p<0.005) immediately following transfusion and there was a positive correlation between the increase and the amount of blood transfused (r=0.74,p<0.05). Arterial oxygen saturation was below 95% in five of eight patients and increased significantly with transfusion (p<0.05). We conclude: 1) thalassemia major and/or its treatment is associated with hypoxemia and a progressive reduction in total lung capacity. 2) Despite the progressive reduction in total lung capacity, splenectomy in patients with thalassemia major increases expiratory reserve volume and thereby increases vital capacity. 3) The previous finding of elevated KCOcarbon monoxide is explained quantitatively as a transient effect caused by blood transfusion. 4) Transfusion in patients with thalassemia major without overt signs of cardiac failure is usually associated with a transient increase in arterial oxygen saturation.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To study the possibility that changes in fetal surfactant composition depend on the availability of inositol, we isolated surfactant material from lungs of fetal and neonatal rats and estimated their plasma inositol concentration. During the 18- to 22-day gestational period the amount of surfactant increases from 0.17 to 3.10 µmol phospholipids/g wet lung. From day 20 onward, 70% or more of the phospholipids is phosphatidylcholine. In this period the relatively high percentage of phosphatidylinositol (8%) in the lung surfactant decreases to 4% whereas the percentage of phosphatidylglycerol increases from 2 to 8% at parturition. During gestation the phospholipid/protein ratio of the surfactant material increase from 3 to 11 and the highest ratio is found immediately after birth. It decreases again 24 h after birth to values characteristic for surfactant from adult rats. The plasma inositol concentration drops during the 18- to 22-day period from 0.81 to 0.26 mmol/liter and a similar decrease in inositol concentration occurs in amniotic fluids. The phosphatidylglyercol/phosphatidylinositol ratio of surfactant correlated negatively with the fetal plasma inositol concentration. It is most likely that the reduction in the level of fetal plasma inositol resulting from a declining production and an increasing metabolism, causes the decrease in phosphatidylinositol and increase in PG content of the surfactant of the fetal rat.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Using four different digoxin kits, it was disclosed that the majority of various samples including amniotic fluid, cord blood, and serum from neonates contained substantial levels of digoxin-like immunoreactive substance. The differences in data seemed to be due to the range of epitopes which are recognized by antidigoxin antiserum. The day-to-day studies on sera serially obtained from infants at birth to 48 days old revealed that the level of the substance (0.31 ± 0.12 ng/ml) in sera of the 1-dayold neonates rapidly declined to the level of 0.1 ng/ml by the 2nd postnatal wk and thereafter gradually declined. The immunological specificity and accuracy of the detection of digoxin-like immunoreactive substance was confirmed by a sample dilution test, a recovery test for standard digoxin, and an absorption test with antidigoxin antiserum. The amniotic fluid and cord blood also contained four to eight times more of a digitoxin-like immunoreactive substance than they did digoxin-like immunoreactive substance. A significant correlation was observed between the levels of digoxin-like immunoreactive substance and of digitoxin-like immunoreactive substance (p<0.01).

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Nitrogen retention and rates of whole body amino nitrogen flux, protein synthesis, and breakdown were measured in 18 neonates during the 72 h immediately postsurgery. The infants were all intravenously fed with a crystalline amino acid source (Vamin), glucose, and Intralipid The infants were divided into two groups based on amino acid intake: either 2.3 SD 0.4 g or 3.9 SD 0.5 g/kg/ day. Nonprotein energy intakes were similar and averaged 81 kcal/kg/day. Group A (n=11) retained 145 SD 110 mg N/kg/day, whilst group B (n=7) retained 315 SD 93 mg N/kg/day (p<0.001). There were no differences seen in flux, synthesis or breakdown. However, group B had significantly higher net protein synthesis rates (synthesis breakdown) (p<0.01). The improved nitrogen utilization in group B was achieved principally by a reduction in endogenous protein breakdown. There were no differences between the two groups in urinary creatinine or 3-methylhistidine excretion. Since these two parameters reflect skeletal muscle turnover the differences between groups in nitrogen retention and turnover appear to be mediated through visceral protein

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:

To identify evidence of essential fatty acid deficiency, we screened 64 patients with cystic fibrosis by analyzing total lipid extracts from plasma. Forty-three had an abnormal linoleate (18:2) level (less than 26%). Thirteen deficient patients (aged 10-24 yr) ingested for 1 yr 7% of their total calories as linoleate derived from a daily supplement of Microlipid. Five deficient patients (aged 10-37 yr) served as controls. Plasma and erythrocyte fatty acid composition were monitored by gas chromatography of total lipid extracts seven times during the twelve month period. Prostaglandins E2and F2αand their 15 keto 13, 14 dihydrometabolite, 6-keto F1α, and thromboxane B2were measured by radioimmunoassay. Sweat tests, oxygen saturation, growth indices, clinical severity scores, compliance, and possible side effects from taking Microlipid were followed. Results showed that oral supplementation with Microlipid can significantly increase plasma and erythrocytes %18:2. One compliant patient died during the study and had normal tissue 18:2 levels. Nine of 13 patients gained more weight while taking Microlipid than in the previous year. No significant changes in sweat electrolytes, clinical scores, or oxygen saturation were found during the study year. Prostaglandin metabolites prostaglandin E2showed an upward trend in supplemented patients, compared to controls. Prostaglandin F2αremained unchanged over 1 yr but showed a trend significantly downward over the final 6 months in supplemented patients. We conclude that linoleate deficiency can be corrected with daily Microlipid supplements and that correction may alter prostaglandin metabolism

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID