Observation of a hybrid spin resonance

A new type of spin depolarization resonance has been observed at the Brookhaven Alternating Gradient Synchrotron (AGS). This spin resonance is identified as a strong closed-orbit sideband around the dominant intrinsic spin resonance. The strength of the resonance was proportional to the 9th harmonic component of the horizontal closed orbit and proportional to the vertical betatron oscillation amplitude. This "hybrid" spin resonance cannot be overcome by the partial snake at the AGS, but it can be corrected by the harmonic orbit correctors.

Dexamethasone treatment and fluid balance in preterm infants at risk for chronic lung disease.

UNLABELLED: The influence of dexamethasone on diuresis in preterm infants has not been well studied. We examined 15 preterm infants at risk for chronic lung disease with gestational ages ranging from 26 to 29 wk (median 27.6 wk) and birthweights ranging from 700 to 1485 g (median 965 g). Urine output, blood glucose, serum urea, serum creatinine, serum sodium and serum potassium, as well as systolic, diastolic and mean arterial pressure were measured on the day before, and on 4 consecutive days after starting treatment with dexamethasone (0.25 mg kg-1 i.v., twice daily). We found an increase of diuresis of 30 ml kg -1 d-1, 48-96 h after starting dexamethasone treatment. This coincided with a gradual but significant increase of serum urea levels and arterial pressure. During the study period, fluid and protein intake remained constant. Blood glucose and serum creatinine levels did not change. Our findings suggest that the increased urine output following dexamethasone treatment might be caused by two factors: (1) pressure diuresis induced by the increase of arterial pressure and (2) an increase of the osmolar load to the kidney due to an increase of serum urea. CONCLUSIONS: This study demonstrates that a significant increase of diuresis occurs in preterm infants, 48-96 h after starting dexamethasone. A careful monitoring of fluid balance during the first days of dexamethasone treatment is recommended.

Postnatal glucose kinetics in newborns of tightly controlled insulin-dependent diabetic mothers.

Infants of diabetic mothers are at risk of developing hypoglycemia postnatally. Strict control of blood glucose during pregnancy might result in adequate glucose homeostasis in the neonate. We followed 15 mother-infant pairs from the beginning of pregnancy until birth. Glucose kinetics in the infants were measured on the first day of life, using a stable isotope dilution technique. Furthermore, levels of alternative substrates, FFA, and ketone bodies were measured. All infants received i.v. glucose from birth onward at a rate of 3.4 +/- 0.7 mg/kg/min (mean +/- SD). There was no relationship between the parameters of control of the insulin-dependent diabetes mellitus in the mothers and glucose kinetics in their infants. Glucose turnover was 5.2 +/- 1.1 mg/kg/min, glucose production rate (GPR) was 1.8 +/- 1.1 mg/kg/min. GPR was significantly lower in the infants studied at the end of the first day of life (p < 0.01), irrespective of the glucose infusion rate. Furthermore, the lower GPR was associated with an increased concentration of ketone bodies, suggesting an increased production of ketone bodies in these infants. The relatively high GPR measured in the infants who were studied in the first hours postnatally may be the result of postnatal hormonal stimulation of glycogenolysis and/or gluconeogenesis. From this study, we conclude that glucose kinetics in infants of tightly controlled diabetic mothers appear to be normal. Interestingly, despite the near-optimal insulin therapy in the mothers, there is a relationship between the SD scores of birth weight and the mean 3rd-trimester blood glucose values.

Fat absorption in premature infants: the effect of lard and antibiotics.

Fat absorption of an adapted cow's milk formula was studied in a randomized controlled trial involving two groups of 18 premature infants (mean gestational age +/- SD: 33.0 +/- 2.9 weeks, range 26.5-37.5 weeks). The triglyceride configuration was modified by the use of lard. This modification did not improve the absorption of fat or energy. Also no difference in serum concentrations of cholesterol and triglycerides was found. Growth velocity during the study was similar in both groups. Detailed analysis of the data revealed that in infants who received (parenterally) antibiotics (mainly ampicillin and netilmicin) a higher coefficient of fat absorption (+20%, P less than 0.01) and of energy absorption (+8%, P = 0.03) was found. Based on these results, we find no support for the use of lard in adapted cow's milk infant formulas to improve fat absorption. In studies of fat and energy absorption the effects of antibiotics have to be taken into account.

Acute effects of pentobarbital-anaesthesia on bile secretion.

Male Wistar rats were equipped with permanent catheters in the bile duct and the duodenum under ether anaesthesia, at least seven days before the experiments. By this technique, the enterohepatic circulation can be interrupted for bile collection without direct surgical intervention. 14C-Pentobarbital (26.6 mumole/100 g body wt) was injected intraperitoneally immediately before interruption of the enterohepatic circulation (NBD, Non-Bile Diverted) or after eight days of bile diversion (BD, Bile Diverted). In NBD rats, bile flow and biliary bile acid excretion were significantly reduced during the first hour after pentobarbital administration when compared to unanaesthetized controls, but markedly increased thereafter. Pentobarbital treatment slightly decreased biliary bile acid excretion in BD rats, but caused a 60% increase in bile flow. Within four hours 22.3 +/- 0.4% and 26.0 +/- 2.7% of the injected radioactivity was excreted into bile in NBD and BD rats, respectively. The calculated osmotic activity of pentobarbital and its metabolites was 47.8 +/- 5.2 microliter/mumole in NBD rats and 37.8 +/- 1.3 microliter/mumole in BD rats. Consequently, pentobarbital treatment affected the bile acid independent fraction of bile flow (BAIF). The calculated BAIF was 2.68 microliter/min/100 g body wt in unanaesthetized animals, but 4.27 microliter/min/100 g body wt in pentobarbital treated NBD rats. Corresponding values for BD rats were 1.70 and 2.38 microliter/min/100 g body wt. It is concluded that pentobarbital anaesthesia affects bile production in the rat by direct and indirect means. Firstly, pentobarbital and its metabolites are rapidly excreted into bile and exert a significant choleretic effect, thereby increasing the BAIF. Secondly, pentobarbital anaesthesia retards the exhaustion of the intestinal bile acid pool, which leads to secondary changes in the biliary excretion process.