An experience of renal replacement therapy in a combined neonatal and paediatric intensive care unit of Hong Kong

Intensive care services are expensive. The experience of developing a combined paediatric and neonatal intensive care unit (ICU) in a regional hospital is reported with reference to the provision of renal support for the critically ill patients. The combined unit is staffed by a team of paediatric intensivists, each of whom has special interest in a subspecialty, including cardiology, respiratory medicine, nephrology and neonatology. In the past 7 years, renal replacement therapy (peritoneal dialysis and haemofiltration) was provided to 40 patients, with comparable mortality and complication rates to other reports. This arrangement has been feasible and might be more efficient than running separate paediatric and neonatal ICUs or combining the paediatric ICU with the adult ICU.     

Effect of deoxynivalenol on neurotransmitters in discrete regions of swine brain

The effect of deoxynivalenol (DON, vomitoxin) on brain amine levels was investigated in swine. DON, a trichothecene mycotoxin, causes suppression of feed intake (anorexia) in susceptible species. Following acute administration of DON to pigs (0.25 mg/kg, IV), concentrations of endogenous catecholamines norepinephrine (NE), dopamine (DA), 3,4-dihydroxyphenyl-acetic acid (DOPAC), and homovanillic acid (HVA), and the indoleamines, 5-hydroxytryptamine (5HT, serotonin) and 5-hydroxyindoleacetic acid (5HIAA) were determined in five brain regions, periodically during the 24 h post-dosing. Analysis was carried out by high performance liquid chromatography, using electrochemical detection.Effects of DON in the swine brain were transmitter, time and region-specific. It was observed that levels of the major transmitters (NE, DA and 5HT) were statistically different from controls in the hypothalamus (Hypo), frontal cortex (FCX) and cerebellum (Cb) up to 8 h post-dosing. Overall, DON administration elevated NE and depressed DA concentrations in these regions, and levels of 5HT which increased initially in Hypo (1 h), had dropped significantly below controls in both Hypo and FCX at 8 h. These alterations, however, were not indicative of known neurochemical changes associated with chemical-induced anorexia. Instead, this data suggested that the neurochemical effects of acute DON exposure might be due to peripheral toxicological events (i.e., vomiting), which overwhelmed its more subtle feed refusal activity.Animal Research Centre; Contribution No. 1743.Research Program Service; Contribution No. R082.     

Inhibition of 2-nitropropane-induced rat liver DNA and RNA damage by benzyl selenocyanate

We observed that pretreatment of male F344 rats with benzyl selenocyanate, a versatile organoselenium chemopreventive agent in several animal model systems, decreases the levels of DNA and RNA modifications produced in the liver by the hepatocarcinogen 2- nitropropane. To clarify the mechanisms involved, we pretreated male F344 rats with either benzyl selenocyanate, its sulfur analog benzyl thiocyanate, phenobarbital or cobalt protoporphyrin IX; the latter is a depletor of P450. We then determined (1) the ability of liver microsomes to denitrify 2-nitropropane, (2) effects on 2-nitropropane- induced liver DNA and RNA modifications and (3) amount of nitrate excreted in rat urine following administration of the carcinogen. Pretreatment with benzyl selenocyanate or phenobarbital increased the denitrification activity of liver microsomes by 217 and 765%, respectively, increased liver P4502B1 by 31- and 435-fold, respectively, decreased the levels of 2-nitropropane-induced modifications in liver DNA (29-70% and 17-30%, respectively) and RNA (67-85% and 30-50%, respectively), and increased the 24-h urinary excretion of nitrate by 157 and 209%, respectively. Pretreatment with benzyl thiocyanate had no significant effect on any of these parameters. Pretreatment with cobalt protoporphyrin IX decreased liver P4502B 1 by 87%, decreased the denitrification activity of liver microsomes by 76%, decreased the 24 h urinary excretion of nitrate by 88.5%, but increased the extent of 2-nitropropane-induced liver nucleic acid modifications by 17-67%. These results indicate that the metabolic sequence from 2-nitropropane to the reactive species causing DNA and RNA modifications does not involve the removal of the nitro group. Moreover, they suggest that benzyl selenocyanate inhibits 2-NP-induced liver nucleic acid modifications in part by increasing its detoxication through induction of denitrification, although it is evident that other mechanisms must also be involved.      

Purification and characterization of the reovirus cell attachment protein sigma 1

It has previously been shown that of all the soluble reovirus-specified proteins present in the infected cell lysate, protein sigma 1 alone possesses the capacity to bind to host cells (P.W.K. Lee, E.C. Hayes, and W.K. Joklik, 1981, Virology 108, 156-163). We found that sigma 1 from urea-disrupted reovirus particles was also capable of such specific binding. Reovirions were therefore used as a source of functional sigma 1. Accordingly, a simple procedure has been developed to purify sigma 1 by subjecting urea-disrupted reovirions to DEAE ion-exchange chromatography. Protein sigma 1 thus isolated was electrophoretically homogeneous and the recovery was estimated to be 50 to 60% of the theoretical yield. The purified protein presumably maintained its native conformation since it was recognized by a panel of monoclonal anti-sigma 1 antibodies previously isolated, and was capable of specifically binding to host cell receptors, agglutinating human erythrocytes and inducing neutralization and hemagglutination-inhibition antibodies. Subsequent chemical crosslinking studies revealed the presence of oligomeric (mostly dimeric) sigma 1 forms in the preparation. The amino acid composition of the purified sigma 1 was found to closely match that inferred from the S1 gene sequence. However, attempts to determine its amino-terminal sequence have not been successful. The p/ of the purified protein was determined to be 6.8. Circular dichroic measurements of the purified sigma 1 indicated that 54 and 19% of its residues were arranged in alpha-helical and beta-sheet secondary structures, respectively.