Showing papers by "Hospital for Sick Children published in 1985"

Human 2-5A synthetase: characterization of a novel cDNA and corresponding gene structure.

Abstract: The enzyme 2-5A synthetase is induced in cultured cells in response to interferon (IFN) treatment. A lambda gt10 cDNA library of mRNA from IFN-induced Daudi lymphoblastoid cells was screened with oligonucleotide probes. Several overlapping cDNAs were isolated and shown to be derived from the human synthetase gene using filter selection and oocyte microinjection assays. The nucleotide sequence of one of these, cDNA 8-2, extended the 2-5A synthetase sequence already described 72 bp in the 5' direction but was found to differ significantly in coding sequence at the 3' end. The longest cDNA isolated (6-2) was approximately 1.4 kb. By Northern hybridization analysis single mRNAs of 1.7 kb were detected in Daudi and T98G (glioblastoma) cells. However, in HeLa cells, four mRNAs ranging in size from 1.5 to 3.5 kb were found, one of which differed at the 3' end. Analysis of both phage and cosmid genomic clones and comparison with genomic DNA indicate that there is a single gene for 2-5A synthetase, comprising at least six exons and five introns, which can undergo a novel form of alternative RNA processing depending on cell type.

Thinking about the threat of nuclear war: relevance to mental health.

Abstract: Ontario students in grades 7-13 responded to open-ended and multiple-choice questions about future concerns, particularly unemployment, job/career plans, and the nuclear threat. Although worries about nuclear war were more frequent than those in other areas, their expression was associated with a sense of social efficacy rather than with feelings of helplessness.

Elevated levels of interferon-induced 2'-5' oligoadenylate synthetase in generalized persistent lymphadenopathy and the acquired immunodeficiency syndrome

Abstract: The levels of the 2'-5' oligoadenylate enzyme synthetase in extracts of peripheral blood mononuclear cells from individuals with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) were measured and compared with synthetase levels in peripheral blood mononuclear cells (PBMs) from healthy heterosexual and homosexual controls. The mean basal synthetase level in heterosexual and homosexual controls was 14 +/- 13 and 12 +/- 9 pmol per hr/10(5) PBMs, respectively. Thirteen individuals with AIDS had a mean basal level of 129 +/- 75 pmol. Serial levels were persistently elevated in six of these individuals over a one- to 10-month period. Twelve of the 13 individuals had antibodies to human T cell lymphotrophic virus-III/lymphadenopathy-associated virus (HTLV-III/LAV). Thirty-three individuals with ARC had a mean basal synthetase level of 68 +/- 84 pmol. Thirty-two of the 33 had antibodies to HTLV-III/LAV. Eleven (33%) have had consistently normal synthetase levels (less than 2 SD above the mean for the homosexual controls, i.e., 30 pmol) over a three- to nine-month follow-up period. Fourteen (42%) had persistently elevated levels over the same period; four (29%) of these developed AIDS during the follow-up period. Eight have had fluctuating levels but have remained clinically well. These studies suggest that persistently elevated synthetase levels in individuals with ARC and antibodies to HTLV-III/LAV indicate progressive virus-induced disease activity. Elevated synthetase levels may be an important prognostic indicator of increased risk of progression to AIDS.

Partial pyruvate decarboxylase deficiency with profound lactic acidosis and hyperammonemia: responses to dichloroacetate and benzoate

Abstract: We describe the successful use of sodium benzoate in a neonate with hyperammonemia associated with congenital lactic acidosis caused by a partial deficiency of the E1 component of pyruvate dehydrogenase (PDH); of note, this biochemical disturbance has not been previously described in PDH deficiency. The pyruvate dehydrogenase complex in skin fibroblasts had 48% of normal activity with a deficiency of the E1 component. The infant presented with rapid onset of a severe metabolic lactic acidosis, hyperventilation, hyperammonemia, and coma. At 30 hours of age continuous peritoneal dialysis was started; however, plasma NH3 concentrations remained in the 300-400 micrograms/dl range over the next 12 hours. Sodium benzoate, 250 mg/kg, was infused intravenously with a decrease in plasma ammonia of 25 micrograms/dl/hr. Hippurate was documented in the urine and peritoneal fluid after benzoate therapy. At 10.5 months of age, 50 mg/kg dichloroacetate was administered orally under fasting conditions, which resulted in a 56 and 62% reduction in the serum lactate and pyruvate levels, respectively; after 2 weeks on dichloroacetate his fasting levels were significantly decreased. Fibroblast PDH activity responded similarly to this drug. In our patient sodium benzoate was rapidly effective in producing a decline in plasma ammonia that was associated with clinical improvement. We feel that its use in organic acidemias deserves further evaluation and, furthermore, that any child with suspected PDH deficiency requires a clinical trial of dichloroacetate.

Intelligence after early brain injury. I: Predicting IQ scores from medical variables.

Abstract: To study how psychometric intelligence is related to early brain damage, the medical histories and Wechsler IQ scores of 407 subjects were analysed by multiple regression techniques. The study separated those medical variables that predicted IQ from those that did not, estimated the relative importance of the predictor variables as modifying influences on intelligence, and established the overall predictive power of significant variable sets. Intelligence varied with some aspects of brain damage but not with others. There was no single predictor of intelligence; instead, there were sets of predictors that operated in contexts of varying width and definition, each set having a different level of predictive power. Intelligence itself was diverse, with different predictive sets for Full Scale, Verbal, and Performance IQ. An analysis of the pattern and magnitude of the nonpredictive and predictive medical variables, and of the predictor variables vis-a-vis each other, reveals some of the principles by which verbal and nonverbal intelligence are represented in the young damaged brain.

Dual-channel electrical stimulators for use by children with diplegic spastic cerebral palsy

Abstract: The paper describes the design of two dual-channel constant-current electrical stimulators for use by children with diplegic spastic cerebral palsy. One stimulator for correction of equinus gait. The technique used to isolate the two stimulus output channels permits expansion to multiple stimulus channels using a single DC/DC convertor. False triggering of the functional stimulator by footswitches has been accounted for electronically. Examples reflecting the use of the device in the course of gait studies are presented.

Effect of inhaled azlocillin, mistabron and combination therapy in children with cystic fibrosis

Abstract: EFFECT OF INHALED AZLOCILLIN, MISTABRON AND COMBINATION THERAPY IN CHILDREN WITH CYSTIC FIBROSIS

Glycosyltransferases Involved in the Biosynthesis of Protein-Bound Oligosaccharides of the Asparagine-N-Acetyl-D-Glucosamine and Serine(Threonine)-N-Acetyl-D-Galactosamine Types

Abstract: Glycoproteins are a diverse group of biopolymers containing one or more carbohydrate chains linked covalently to a polypeptide backbone. The carbohydrate chains are classified according to the linkage between sugar and amino acid. This chapter will deal with the biosynthesis of mammalian and avian protein-bound oligosaccharides linked to polypeptide via asparagine-N-acetyl-D-glucosamine (Asn-GlcNAc, N-glycosidic) and serine(threonine)-N-acetyl-D-galactosamine [Ser(Thr)-GalNAc, O-glycosidic] linkages. Several recent reviews have considered various aspects of this topic (Schachter, 1978; Schachter and Roseman, 1980; Schachter and Williams, 1982; Beyer et al., 1981).

Q fever and experimental sheep. From the International Council for Laboratory Animal Science.

Abstract: In August 1983 a Symposium was held in Vancouver to discuss Q fever as a hazard to humans in contact with infected sheep. On the basis of new preliminary information presented and discussion at the Symposium, an attempt has been made in this document to supplement published guidelines for the conduct of sheep research.

Production and characterization of a monoclonal antibody to a human interferon-induced double-stranded RNA-binding Mr 68,000 protein kinase

Abstract: One of the interferon-induced proteins thought to be involved in the antiviral effects of interferon is a double-stranded RNA-dependent protein kinase. This paper reports the development of a monoclonal antibody, 10A5, that recognizes a protein that co-migrates with the double-stranded RNA-dependent protein kinase at an approximate molecular weight of 68,000. Levels of this protein and of the protein kinase activity increase 3-fold on interferon treatment of T98G cells. The specificity of the monoclonal antibody was determined by ELISA, immunoblotting, and immunoprecipitation procedures. Furthermore, immunoaffinity chromatography of an interferon-induced T98G cell extract previously phosphorylated in the presence of double-stranded RNA and radiolabeled ATP resulted in the specific elution of a phosphorylated Mr 68,000 protein from the monoclonal antibody 10A5-Sepharose column. Monoclonal antibody 10A5 recognizes both native and denatured protein kinase, independent of double-stranded RNA binding or phosphorylation, and should therefore serve as a useful tool in analyzing the role of the double-stranded RNA-dependent protein kinase in the mechanism of interferon action.

Total parenteral nutrition in the newborn: an update.

Abstract: This review will focus first on the effect of providing total parenteral nutrition (TPN) on the outcome of various nutrient-depleting diseases in infants, then on a discussion of the need for, and metabolism of, “new” essential nutrients which are recommended for inclusion in TPN regiments: biotin, carnitine, zinc, copper, iron, and others.

376 age-dependent verapamil kinetics affect pediatric oral dose requirements

Abstract: Although intravenous verapamil effectively terminates supraventricular tachycardia (SVT) in children, its utility as a chronic oral antidysrhythmic drug has been disappointing. To assess whether drug kinetics contribute to this problem, we measured serum concentrations before and for 24 hours after a maintenance oral dose of verapamil (mean dose 1.36 mg/kg, range 0.4-2.9 mg/kg) in 7 children with a median age of 10.8 yrs (range 2.8-15.3 yrs). All had SVT controlled by chronic oral verapamil at mean serum peak and trough concentrations of 248±117 and 64±38 ng/ml, respectively. We found several clearly age-dependent kinetic parameters: younger children demonstrated faster drug uptake “Tmax” (p <.005), lower relative bioavailability “F” (p<.01), smaller volume of distribution “Vd” (p <.005) and slower elimination half-life “t ½ β” (p <.001). Younger children also exhibited a possible diurnal variation in drug kinetics. There was no significant age-relationship in distribution half-life “t½α” or drug clearance rate. Although these changes have opposing effects on serum concentrations, their net effect in young children is for a greater dosage requirement, and perhaps a shorter dosage interval, than are currently recommended. *Supported in part by G.D. Searle & Co. of Canada, Ltd., and the Ontario Heart and Stroke Foundation.

The effect of diet composition on energy metabolism, substrate utilisation and growth in the vlbw infant

Abstract: Medium-chain-triglycerides (MCT) induce a decrease in fat storage in adult animals. To study the effect of MCT on quality of growth in the VLBW infant, oxidation (ox) and accretion (accr) of energy, protein, fat and carbohydrate have been measured in 20 growing VLBW infants, fed either an MCT enriched formula (gp 1; n=8) or an LCT formula (gp 2; n=12). 16 studies were performed in each group, combining indirect calorimetry, macronutrient balance and anthropometry. Weight and length gain simulated intra-uterine growth rate in both groups. Subscapular skinfolds and calculated body fat were similar in both groups, but higher than in the fetus of comparable postconceptional age. CONCLUSIONS: 1) The similar energy expenditure and fat oxidation indicate that MCT are not preferentially oxidised. 2) Consequently, MCT have to be chain elongated before storage. 3) The improvement of protein accretion to a level exceeding the intra-uterine accretion rate and improved absorption for MCT vs LCT indicate that body composition can be manipulated by isocalorically altering diet composition.

Hematin-Assisted Intramolecular Oxygen Transfer Mechanism Is Involved in the Formation of 8-Hydroxy-11,12-epoxyeicosa-5,9,14-trienoic Acid (8H-11, 12-EPETE) from 12-HPETE

Abstract: We recently described the isolation and structure of two hydroxyepoxides formed from 12-HPETE by an enzyme system present in rat lung (Pace-Asciak et al.,1983a). These were shown to be 8-hydroxy-ll,12-epoxy (8H-11,12-EPETE) and 10-hydroxy-ll,12-epoxy (1 OH-11,12-EPETE) eicosatrienoic acid. Evidence was presented to show that both oxygen atoms in the hydroxyepoxides were derived from molecular oxygen (Pace-Asciak et al., 1983a). Also, when [18O]oxygenated 12-HPETE was incubated with this enzyme preparation, 18O atoms were found in both the hydroxyl and the epoxide groups, suggesting that the hydroxyl group at carbon 8 and carbon 10 was derived from the hydroperoxide of 12-HPETE (Pace-Asciak et al., 1983a). However, whether the terminal hydroxyl group of the hydroperoxide of 12-HPETE was transferred via an inter- or intramolecular mechanism was not determined. The present chapter reports evidence with a mixture of [16O]- and [18O]-labeled 12-HPETE to show a unique intramolecular rearrangement of 12-HPETE into the hydroxyepoxides catalyzed by bovine hematin in a protein-free environment as well as by a rat lung cytosol fraction.

Cortisone fails to affect levels of islet cell surface antibodies and incidence of diabetes in the BB rat

Abstract: Cortisone acetate (250 μg/kg·day) was given by im injections to 40 21-day-old diabetes-prone BB rats. The animals were followed longitudinally to determine islet cell surface antibodies (ICSA), as an expression of an abnormal immune reaction against the pancreatic islet cells and plasma glucose to estimate the degree of metabolic control. ICSA were detected 10–150 days before the diagnosis of diabetes. In the cortisone-treated group the diabetic rats showed significantly higher ICSA values compared to the nondiabetic ones, both in frequency of positive tests (P < 0.05) and in mean binding values (P < 0.02). In the control group, no difference in ICSA levels were seen between diabetic and nondiabetic rats. The cortisone regimen also failed to influence the degree of insulitis, commonly associated with diabetes in these rats. These experiments in well defined animals which spontaneously develop diabetes do not support the use of low dose cortisone treatment in attempts to improve or prevent insulin-dependen...