摘要:

Arginine vasopressin (AVP), atrial natriuretic factor, and water balance were examined in the infants with or without hronchopulmonary dysplasia (BPD) during the first 4 wk of life. Fourteen premature infants, nine in the early stage of BPD secondary to respiratory distress syndrome (BPD infants) and five healthy low birthwt infants (LBW infants), were the subjects of this study. The water and sodium balance, renal function, and plasma AVP and atrial natriuretic factor concentrations were determined during the first 4 wk of life. Plasma AVP and atrial natriuretic factor levels of BPD infants at the 4th wk of life were higher than those of LBW infants at the corresponding age. Urine osmolality was higher and free water clearance was lower in BPD infants at the 4th wk of life when compared with each parameter in LBW infants, respectively. PaCo2of BPD infants at the 4th wk of life was more elevated than that of LBW infants. These results suggest that elevated plasma AVP level may be related with pulmonary abnormalities and that atrial natriuretic factor may hence compensate the water retention resulted from the functionally activated AVP in the early stage of BPD.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Heat stroke and other hyperthermia-related crises are serious clinical problems in childhood and adolescence. Rapid cooling is required to reduce morbidity and mortality. A variety of effective cooling methods exist, and some may interfere with monitoring and resuscitation or are not readily available. We studied in 12 pigtail monkeys the pathophysiology of immersion hyperthermia (42°C) to cardiac arrest (1 min no flow) and CPR plus cooling to normothermia for restoration and stabilization of spontaneous normotension. This was followed by intractable shock and secondary arrest. These studies gave us the opportunity to compare two simple cooling methods applied during and after CPR: group I (n= 6) received application of ice bags to the groins, axillae, and neck. Group II (n= 6) received ice bags plus cold water wetting (sponging) over the entire anterior surface of trunk and extremities, plus fanning. CPR restored spontaneous circulation in four of six in each group, after CPR of 1.5–16 min (NS between groups). Speed of cooling correlated with speed of stabilization of spontaneous normotension. After cardiac arrest and during and after CPR, rectal temperature had declined from a lethal level of 42.2°C to a safe level of 38.5°C within 45 ± 6 (38–53) min in group I, and within 28 ± 4 (23–32) min in group II (p< 0.05). Epidural and esophageal temperatures declined more rapidly than rectal temperature. For critical hyperthermia, we recommend immediate application of ice bags, cold water wetting (sponging), fanning, and head cooling combined when invasive blood cooling (the most effective method) is not immediately available

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Palmitic acid is a minor component of natural surfactant and has been used to modify lipid extracts of natural surfactants to optimize theirin vitrosurface properties. The metabolic fate of palmitic acid in surfactant is unknown. The clearance of surfactant-associated radiolabeled palmitic acid after intratracheal administration was investigated with trace doses of surfactant in the adult rabbit and with trace and treatment doses in the 28-d fetal rabbit and the 132-d fetal sheep. Palmitic acid was cleared rapidly from the airways, with less than 2% of the radiolabel recovered as free palmitic acid in the alveolar wash by l h in all models. Recovery as free palmitic acid in the total lung at 2 h was 2% in the adult rabbit and 3% both doses in the preterm rabbit. In the preterm sheep, the recovery as free palmitic acid in the total lung was approximately 2% of the trace dose and 1 % of the treatment dose by 5 h. Between 5 and 15% of the instilled palmitic acid was used as substrate for phospholipid synthesis by the lung in the different models. About 30% of the palmitate derived label was recovered in lipid extracts of liver 30 min after trachéal instillation of labeled surfactant in adult rabbits, whereas only 5—10% of the palmitate derived label was found in liver lipids in the preterm animals. In contrast to palmitic acid, radiolabeled triglycéride was cleared much more slowly from the airspaces and lungs of preterm sheep. Inasmuch as large amounts of palmitic acid are cleared rapidly from airspaces and lung tissue, it will not have a prolonged effect on the surface properties of surfactant but it may serve as a precursor for lung lipid metabolism.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

We have previously shown that lactate is produced by the ovine fetal lung. Inasmuch as factors that might affect lactate production, such as pulmonary glucose and oxygen uptake, change late in gestation we investigated whether pulmonary lactate metabolism also changes. Eleven chronically catheterized fetal lambs were studied over 119–141 d gestation. Lactate, glucose, and oxygen concentrations were measured in the pulmonary artery (PA) and vein while lung blood flow was determined using labeled microspheres. Between early studies (≤127 d) and studies near term (≥134 d) PA lactate levels did not change, but due to increasing pulmonary blood flow, lung lactate delivery rose 51% (p < 0.05). Because of a decline in PA glucose, lactate also made up a larger fraction of the major nonnitrogenous substrate in PA blood near term (p < 0.001). Despite this, no net pulmonary uptake of lactate occurred. Lactate production continued, but decreased by 80% between early and late studies (p < 0.05) and the maximum fraction of glucose uptake that could be accounted for by lactate production dropped from 0.78 to 0.20 (p < 0.025). Correlations were found between lung lactate production and both glucose delivery (p < 0.005) and PA glucose concentration (p < 0.05). The ratio between lactate production and glucose uptake also correlated with PA glucose (p < 0.05). No relationships were observed between lactate production and PA oxygen content, oxygen delivery, lactate concentration, or lactate delivery. The decreasing fraction of glucose uptake explained by lactate production suggests that metabolism of pulmonary glucose is altered near term. The correlation between decreasing glucose delivery and declining lactate production also suggests that glucose itself influences this change.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To assess the effect of patent ductus arteriosus (PDA) on left ventricular output (LVO) we studied stroke volume (SV), LVO, and heart rate (HR) in 21 very low birth wt preterm neonates with clinically symptomatic PDA before and after surgical ligation. Six additional infants were also studied before PDA with left-to-right shunt was detectable by the pulsed Doppler technique. Gestational age (median and range) was 28 (24–32) wk. SV was measured by duplex Doppler and M-mode echocardiography, and LVO was calculated as product of SV and HR. LVO was 419 (305–562) mL/min/kg during symptomatic PDA. It decreased to 246 (191–292) mL/min/ kg after ligation (n = 21, p< 0.001). SV was 2.69 (1.98–4.10) mL/kg during symptomatic PDA decreasing to 1.63 (1.22–1.98) mL/kg after ductal closure (n = 21, p< 0.001). HR did not change after ductal closure. In the six infants with three examinations, LVO and SV were normal before detectable ductal left-to-right shunt and after ligation, but LVO was increased by 59.5 ± 23% (mean ± SD) (p < 0.05), and SV by 60 ± 32% (p < 0.05) during symptomatic PDA. In conclusion, preterm neonates with RDS, requiring mechanical ventilation, increased LVO during symptomatic PDA by increasing their SV, and not by changing their HR.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To explore the possibility that intraamniotic administration of digoxin is an effective treatment regimen for fetal tachyarrhythmia, we injected digoxin into the amniotic fluid cavity of pregnant sheep and examined the time course of digoxin distribution to the fetal and maternal plasma compartments. Animals were studied in two groups according to digoxin dosage: 0.7–1.8 nmol/kg fetal body wt in the high-dose group (n = 6) and 0.1–0.6 nmol/kg fetal body wt in the low-dose group (n = 14). Within 1 h, plasma digoxin concentrations in the high-dose and low-dose groups were 18.2 ± 15.0 nmol/L and 2.7 ± 0.8 nmol/L, respectively (values are expressed as mean ± SD). At 6 h digoxin concentrations were 13.8 ± 7.0 and 3.1 ± 0.9 nmol/ L, and at 24 h they were 2.3 nmol/L (n = 1) and 1.8 ± 1.2 nmol/L, respectively. Peak maternal digoxin levels were about one-tenth fetal values in the high-dose group and undetectable in the low-dose group. Fetal digoxin concentrations were significantly greater in the descending aorta than in the umbilical vein (p < 0.02). Fetal arterial blood pressure and heart rate were not significantly different from control at any time after digoxin administration. These results demonstrate that digoxin is rapidly taken up into the fetal circulation from the maternal amniotic cavity. The exact mechanism whereby this occurs is unknown, but transplacental transfer from the maternal circulation is not involved. Our findings suggest that intraamniotic administration of digoxin may be an alternative treatment for fetal tachyarrhythmias when direct administration of antiarrhythmic agents is ineffective or produces maternal toxicity.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Through oxygen free radical production, xanthine oxidase (XOD, E.C.1.2.3.2) has been implicated in the pathogenesis of postischemic and hyperoxic tissue injuries among newborn. We measured the activity and evaluated the kinetic characteristics of XOD in human fetal liver, intestine, brain, and myocardium. Both the fetal liver and intestine contain a high XOD activity through gestation. The activity increases in the liver and decreases in the intestine with advancing gestation. The apparent Km for hypoxanthine is 4.8–5.5 μM in the intestine throughout gestation and in the liver at term but higher than 30 μM in the liver during the first half of pregnancy. The activity is undetectable both in the fetal brain and myocardium throughout gestation. Thus, XOD activity is present at least in the liver and intestine to account for the oxidation of hypoxanthine and xanthine. However, direct evidence for adenine nucleotide catabolism, followed by oxidation of the accumulated hypoxanthine during tissue reoxygenation in the human liver or intestine is not available.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The feasibility of using spectral edge frequency (SEF) as a single quantitative measure of the maturation of electrocortical activity is demonstrated in a large number of fetal lambs studied throughout the 3rd trimester. A total of 43 electrocortical recordings obtained from 23 fetal lambs ranging from 116–140 d were subjected to power spectral analysis using the fast Fourier transform. Spectral edge frequency was calculated as the frequency below which 90% of the power resides. The SEF was found to be highly sensitive in identifying the transition between high-voltage slow-activity and low-voltage fast-activity electrocortical activity. By 125 d, the distribution of SEF clearly showed two distinct populations, a low SEF with peak values ranging from 3–9 Hz; and a high SEF (SEFH) with values ranging from 13–23 Hz. Increase in gestational age was associated with a progressive increase in SEFH, which can be described by the linear function (SEF = 0.53GA–51.3). This progressive increase in SEFHreflects the gradual acquisition of faster frequencies. In contrast, low SEF declined with age before 130 d, but then stabilized at 4 Hz throughout the rest of gestation. As a result, there was a gradual increase in the separation between SEFHand low SEF as a function of gestational age.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

It has been suggested that sugar cataracts associated with diabetes mellitus result from the accumulation of excess sorbitol within lens fibrils. Swelling of lens fibrils occurs when water moves in to maintain osmotic balance; the excess water causes disruption of fibrils and cataract formation. Other studies have indicated that more than sorbitol-induced osmotic stress is involved. Our study used lenses collected from rats after 21 or 44 d of streptozotocin diabetes. Cataracts formed in untreated 44-d streptozotocin diabetic rats, but were not apparent in the 21-d untreated diabetic animals. Lens sorbitol increased in the diabetic animals both before and after cataract formation. Lens taurine varied inversely with the sorbitol content in a fashion that resulted in no net change in total lens osmoles. Lens water did not increase in the diabetic animals with or without cataracts. The aldose reductase inhibitor Sorbinil prevented the increase in lens sorbitol in both the 21− and 44-d streptozotocin diabetic rats; cataract formation was prevented in the 44-d diabetic animals. The lens water in untreated diabetic animals with cataracts did not differ from lens water in the Sorbinil-treated diabetic animals that did not develop cataracts. Sorbinil treatment of diabetic animals was associated with normalization of both lens sorbitol and taurine levels. Taurine has been shown to serve both as an osmoregulator and as an antioxidant. The apparent increase in lens osmolality attributed to sorbitol was counterbalanced by an equimolar reduction in taurine concentration. The reciprocal relationship between taurine and sorbitol reduces the likelihood of an osmotic mechanism for sugar cataractogenesis; the reduced lens taurine, however, may increase the risk of lens protein oxidation and subsequent cataract formation. Thusin vivosugar cataract formation may be an oxidative process rather than an osmotic phenomenon.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The aim of this collaborative study was to investigate whether guanidino compound analyses in the biologic fluids can be used as a complementary diagnostic parameter for hyperargininemia. Guanidino compounds were determined in the biologic fluids of all known living hyperargininemic patients using a cation exchange Chromatographie system with a fluorescence detection method. The serum arginine, homoarginine, α-keto-δ-guanidino-valeric acid, argininic acid, and N-α-acetylarginine levels of all the hyperargininemic patients are higher than the normal range. Similar increases were seen for the urinary excretion of α-keto-δ-guanidinovaleric acid and argininic acid. Untreated hyperargininemic patients have the highest guanidino compound levels in cerebrospinal fluid. However, even under therapy, the arginine, homoarginine, α-keto-δ-guanidinovaleric acid, and argininic acid levels in cerebrospinal fluid are still increased. Protein restriction alone is not sufficient to normalize the hyperargininemia, but protein restriction together with supplementation of essential amino acids with or without sodium benzoate decreases further the arginine levels. However, whereas the argininemia can be normalized, the catabolites of arginine are still increased. We conclude that the urinary amino acid levels may remain normal in hyperargininemia, whereas consistent increases of the guanidino compounds are observed. Thus, guanidino compound analyses can be used as a complementary biochemical diagnostic parameter for hyperargininemia. Although the argininemia can be normalized by therapy, the levels of the catabolites of arginine are still elevated.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID