摘要:

SummaryCarnitine, an important cofactor in the transport of fatty acids to the interior of cell mitochondria, is depleted in myocardial tissue of guinea pigs submitted to diphtheric toxin administration. Mortality rates were reduced in these animals by supplying exogenous amounts of carnitine. The accumulation of fatty acids in the cytoplasm of human heart cells reported in cases of diphtheria suggests that carnitine might possibly be depleted in human myocardium as well.For the purpose of studying the effect of carnitine administration, 132 diphtheric patients were randomly divided into two groups, one of them (carnitine-treated group,n=73) receiving DL-carnitine, 100 mg/kg/day during 4 days after admission, in addition to routine treatment, which was prescribed for this and the control group (n=59). The presence of myocardial damage was evaluated by clinical, electrocardiographic, radiological, and enzymatic criteria. Carnitine administration resulted in decreased incidence of heart failure (P=0.0475), of pacemaker implants (P=0.0256), and of lethality indexes due to myocarditis (P=0.013). We suggest that carnitine can play an important role in the treatment of diphtheric patients.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryThe electromyographic activity of an upper airway muscle (genioglossus, GG) and the diaphragm were studied in 10 adult and three young anesthetized rabbits during progressive asphyxia induced by airway occlusion. Results were similar for both age groups. Peak inspiratory activity of GG muscle increased more than that of the diaphragm during both the hyperpnea and gasping (P<0.05). The increase in GG activity during gasping was not significantly different from that during hyperpnea even though an important stimulus, arousal, was absent during gasping. During end stage asphyxia, as the strength of gasps grew weaker, the rate of loss of GG muscle activity was greater than that of the diaphragm. However, GG activity remained greater than that of the diaphragm at the time of the last spontaneous gasp. As asphyxia progressed, inspiratory duration and the inspiratory contour of integrated electromyogram activity of both muscles changed. These data indicate differences in the control mechanism of the genioglossus and diaphragm during acute severe asphyxia. Increased upper airway muscle activity seen during gasping should help preserve upper airway patency and facilitate autoresuscitation by gasping. These observations of coordinated changes in timing and activity of two functionally different respiratory muscles support the concept that gasping is a highly organized function of the respiratory centers.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryIn this study, we have investigated the possible role of the proaggregatory arachidonic acid (AA) metabolite thromboxane, in the impaired function of neonatal platelets. In platelet-rich plasma thromboxane production (measured by radioimmunoassay of thromboxane B2) was not different between neonates and adults when stimulated by thrombin (at 0.1 or 1.0 U/ml) or collagen (70μg/ml) although neonatal platelets produced decreased thromboxane (TBX2) postepinephrine stimulation. In response to 1 U/ml thrombin, adult and neonatal platelet-rich plasmas produced mean values of 3.41 ± 0.35 (SEM) and 3.11 ± 0.49 pmol of TXB2/106platelets, respectively. Production of TXB2in response to 0.1 U/ml thrombin was not dissimilar between neonates (1.01 ± 0.46 pmol) and adults (1.04 ± 0.38 pmol). When collagen was used as the aggregating agent, TXB2/production was also not significantly different with values of 2.44 ± 0.48 and 1.90 ± 0.46 pmol/106platelets produced by adult and neonatal platelet-rich plasma, respectively. In response to 200μM epinephrine, adult platelets produced 1.03 ± 0.39 pmol TXB2/106platelets while neonatal platelet TXB2production was significantly decreased (0.15 ± 0.04;P<0.05). Thromboxane production in response to AA, however, was markedly elevated in neonatal platelet-rich plasma. When 200 and 400μM concentrations of AA were used as the aggregating stimuli, neonatal platelet rich plasma produced 3.17 ± 0.77 and 8.0 ± 1.47 pmol TXB2/106platelets, respectively. These values were significantly elevatedP<0.02 and <0.005) when compared to mean values of 0.41 ± 0.10 and 3.32 ± 0.15 pmol in adult platelet-rich plasma. This elevated thromboxane production was not, however, inherent in neonatal platelets since when washed platelets were studied, results were reversed. Adult platelets produced more thromboxane at all doses of AA evaluated. These results suggest that the elevated response to exogenous AA observed in neonatal platelet-rich plasma results from as yet undetermined plasma factors. The reported deficiencies in platelet function in the newborn clearly do not result from deficient thromboxane production poststimulation with the physiologic aggregating agents collagen and thrombin. Moreover, our study introduces a new and possibly important difference between adult and neonatal plasma, namely, the differential response to exogenous arachidonic acid.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummarySoft neurologic signs were evaluated in 101 Barbadian school children, ages 4-11 years, who were malnourished in the first year of life, and 101 comparison children matched for age, sex, and handedness, but who had no history of malnutrition. Previously malnourished children performed significantly slower than comparison children on several timed motor tasks when using the nondominant hand only. Boys were found to perform significantly slower than girls, and younger (4-7 years of age) children performed slower than older (8-11 years of age) children. A model is presented that displays interrelationships among previous malnutrition, soft neurologic signs, classroom behavior, intelligence, and physical growth. In summary, slow motor performance was associated with lower verbal and performance IQ and the presence of attention deficit disorder, as assessed by the child's teacher. The time to perform the motor tests was unrelated to measures of physical growth.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryInhibition of prostaglandin cyclooxygenase augments hypoxic pulmonary vasoconstriction. We used a neonatal lamb lung preparation perfused with Krebs' bicarbonate buffer to characterize and quantify prostanoids produced by the pulmonary vasculature from endogenous arachidonic acid in the absence of formed blood elements during ventilation with normoxic and hypoxic gas mixtures. Prostaglandin (PG) I2synthesis increased from 6.4 ± 2.7 ng/min (SEM) during normoxic ventilation to 14.3 ± 5.4 ng/min during hypoxia and returned to 4.7 ± 1.2 ng/min with resumption of normoxia. These data demonstrate that hypoxia stimulates pulmonary vascular synthesis of prostaglandin I2from endogenous substrate in neonatal lambs and suggest that the augmentation of hypoxic pulmonary vasoconstriction by prostaglandin cyclooxygenase inhibition is due, at least in part, to interference with the synthesis of this vasodilator prostanoid.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryHypoxia is a potent stimulus to the release of vasopressin in fetal sheep, and plasma concentrations of the hormone correlate inversely with fetal oxygenation. Since 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. Therefore, we 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 between 111 and 141 days 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. Following 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. Following intra-amniotic injection of vasopressin, levels remained increased for at least 24 h.Thus, 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 measured 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 inutero. Despite elevated concentrations of vasopressin in amniotic fluid, no associated changes in intrauterine pressure were discerned.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryThe present investigation examines the biochemical and physiologic changes produced in fetal rabbit lungs by adding a prostaglandin synthetase inhibitor, sodium indomethacin trihydrate, to the pulmonary perfusate. A control group was similarly perfused without adding indomethacin. The ductus arteriosus was ligated and perfusion was then continued for 2 h while pulmonary artery pressures were monitored. At the end of this period, with perfusion continuing, the lungs were inflated with air at 5 cm H2O increments. Volume changes were recorded. After deflation, the lungs were lavaged with normal saline. Phospholipids were extracted from lung homogenates and lavage. Total lipid phosphorus was determined. Pulmonary vascular resistances in both groups manifested a sharp increase in pressure with ligation of the ductus. After 2 h of perfusion, pulmonary pressures in the control groups had returned very nearly to preligation levels, while in the indomethacin-treated group, pulmonary pressures remained significantly elevated. The first full inflation produced a slight fall in pulmonary vascular resistance in all control animals and a slight rise in all the treated rabbits. Perfused but untreated lungs had higher volumes during inflation as compared to both indomethacin-perfused lungs and unperfused untreated lungs. In this model, prostaglandins appear to have a significant role at two key points in transition: 1) the gradual accommodation to mechanically or hemodynamically mediated increases in pulmonary vascular resistance and 2) the drop in pulmonary vascular resistance which occurs with the first inflation of the lungs. No direct effect of prostaglandin inhibition on surfactant production was documented.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryAlthough body size and muscle mass increase considerably during growth in children, certain aerobic responses to exercise appear to be regulated so that the delivery of oxygen to muscle is maintained at optimized levels. We proposed that the relationship between oxygen uptake, (&OV0312;O2) and heart rate (HR) was one of the regulated responses. We further hypothesized that the increase in &OV0312;O2per increase in HR during progressive exercise would differ in subjects of different size, but when normalized to body weight would be constant since changes in muscle mass are highly correlated to changes in body mass. To test this, we performed a cross-sectional study of 107 normal children, 50 girls and 57 boys ranging in age from 6 to 17 years. The protocol consisted of a continuously increasing work rate on a cycle ergometer, to the limit of the child's tolerance (ramp forcing function). Gas exchange was measured breath-by-breath for the determination of &OV0312;O2, and heart rate was measured beat-by-beat. We used linear regression techniques to determineM, the slope, andB, theyintercept of the equation: &OV0312;O2=Mx HR -B. In both boys and girls,Mincreased significantly with body weight, but when normalized for body weight (M/kg), there was no systematic change with increasing weight or age, the mean value being 0.33 ± 0.10 ml/min/kg (SD). The mean value for the boys was 0.37 ± 0.10 which was significantly greater than that of the girls (0.29 ± 0.08,p<0.01). Using allometric equations, we foundM,B, and the O2-pulse (&OV0312;O2/HR) at a heart rate of 140 beats/min and at the anaerobic threshold, all scaled in direct proportion to body weight (i.e., to 1.0 power of body weight). We conclude that during growth, the output of the heart is closely tied to the size of the muscles so that delivery of oxygen during exercise is maintained at optimized levels from early in childhood.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryPlasma branched chain amino acid levels and their respective ketoacid analogues were determined in seven maple syrup urine disease patients ranging in age from 12 h to 12 years. One hundred one pairs were analyzed. There was a high degree of correlation between the amino acid and its ketoacid analogue at every amino acid level. The coefficient of correlation (0.84) was highest for leucine-α-ketoisocaproic acid. The ratio of ketoacid analogue to amino acid, (0.87), was also the greatest for leucine. The close correlation implies that adequate monitoring for therapy can be accomplished by the use of the technically simpler and more rapid determination of the plasma branched chain amino acids.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

SummaryStudies of maternal metabolism during pregnancy have focused principally upon the latter half of gestation. However, maternal metabolic adaptations to pregnancy may occur at all stages of pregnancy. To study maternal metabolism throughout pregnancy, we developed a chronically catheterized rabbit model in which animals could be studied under conscious, stress-free conditions when nonpregnant and then serially throughout pregnancy.Anesthesia produced marked hyperglycemia. In contrast, chronic catheterization and daily handling did not affect blood concentrations of glucose, lactate, ketone bodies, or free fatty acids, or food intake. Glucose concentration decreased with pregnancy to a value at term equal to 85% of the prepregnancy value. Lactate concentration rose significantly in the second half of pregnancy but changes in free fatty acids and ketoacid levels were not significant. These results are discussed from a comparative physiologic point of view, emphasizing the unique aspects of rabbit metabolism during pregnancy and the importance of performing such studies under conscious, stress-free conditions.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID