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Biomedical subjects

C D Moyes

Publications and source records attributed to C D Moyes.

At least 19 recordsLinked to original sources
PubMed1995

Respiratory symptoms and environmental factors in schoolchildren in the Bay of Plenty.

AIMS: To determine the prevalence of respiratory symptoms in children and to examine associations with environmental factors in the Bay of Plenty. METHODS: International Study of Asthma and Allergies in Childhood (ISAAC) questionnaires were distributed to 13-14 year old children and to care-givers of 6-7 year old children as part of the ISAAC study. RESULTS: Completed questionnaires were received for 2614 primary and 2752 secondary students. Analysis by district showed no consistent association with exposure to industrial emissions from paper mills, natural sulphur fumes, or climatic variation. All districts are subject to high levels of pollen. Symptom prevalence was close to the mean for New Zealand centres participating in the ISAAC survey. Night cough and nasal symptoms were more common in secondary pupils exposed to smoking in the home, but there was no consistent association between passive smoking and wheeze or diagnosed asthma. Children from larger households reported less wheezy symptoms and less diagnosed asthma. CONCLUSIONS: There was no consistent evidence of an effect on respiratory morbidity from natural fumes, industrial air pollution, or climate. The indoor environment is probably of greater importance in this population.

Adolescent↗
PubMed1994

Hypernatraemia: still seen as a problem in paediatric practice.

AIMS: To illustrate that hypernatraemia is still seen as a problem in paediatric practice and to discuss its management. METHODS: A collection of four patients with hypernatraemia from different causes are reported. Recommended treatment include initial plasma expanders, where necessary, followed by gradual rehydration to prevent cerebral oedema using fluid containing 75-80 mmol/L of sodium until adequate urine output is observed, followed by a maintenance rate of solution containing 35-40 mmol/L of sodium over 48 h. RESULTS: All four patients recovered completely and without complications. CONCLUSIONS: Hypernatraemia is still seen in practice as an important problem. Recommended treatment is gradual rehydration with appropriate concentrations of electrolyte and glucose mixture.

Humans↗
PubMed1994

Temperature and pH effects on Ca2+ sensitivity of cardiac myofibrils: a comparison of trout with mammals.

Active salmonids maintain myocardial contractility at temperatures that are cardioplegic for mammals. We postulated that myofibrillar Ca2+ sensitivity in the trout heart might 1) exhibit lower temperature dependence and/or 2) be greater over the range of physiological temperatures. Temperature-induced changes in intracellular pH may also play a role as alkalosis typically increases calcium affinity of myofibrillar adenosinetriphosphatase (ATPase). Ca2+ sensitivities of ventricular myofibrillar ATPase were determined in rats and in rainbow trout (Oncorhynchus mykiss) over a physiological range of pH and temperatures. Maximal myofibrillar ATPase activities of each species were similar and equally affected by temperature. Trout myofibrillar ATPase lost Ca2+ dependence at 37 degrees C. At constant pH, reduced temperature decreased calcium affinity more in trout (0.35 pCa/10 degrees C) than in rat (0.08-0.16 pCa/10 degrees C). Under alpha-stat conditions, the effects of temperature were reduced in both trout (0.2 pCa/10 degrees C) and rat (no significant effect). Over trout physiological temperatures, Ca2+ sensitivity was greater than rat at 37 degrees C. Qualitatively similar results were observed in studies measuring tension in skinned trout ventricular fibers. One mechanism by which the trout heart is able to maintain contractility at low temperatures is through the inherent higher Ca2+ sensitivity of the contractile element compared with mammalian species.

Adenosine Triphosphatases↗
PubMed1992

Immunisation status of children in the eastern Bay of Plenty.

AIM: To assess the status of immunisation of children in the eastern Bay of Plenty. METHOD: Survey of general practitioner records and case notes of all resident children born over a period of two years and aged from five to 29 months. Immunisation was considered up to date if received within a reasonable period of the expected time. RESULTS: One thousand five hundred and ninety-three children were studied (97% of those known to be resident). The six week immunisations were received by 91%, 88% received the three month, and 81% the five month vaccines. Delivery of second year immunisation was much less successful, only 72% receiving measles or MMR vaccine despite publicity about a current measles epidemic and 61% the eighteen month vaccines. CONCLUSION: Forty-three percent children of two years of age had not received the full recommended immunisation schedule. Some of the contributing factors were identified and measures that could improve immunisation uptake are discussed.

Child, Preschool↗
PubMed1992

Hepatitis B vaccination in children: five year booster study.

AIM: to demonstrate that appropriate doses of hepatitis B vaccines would be protective for at least five years in children. This would be shown by administering booster doses and measuring the response. METHODS: 2 micrograms intramuscular (IM) doses of Merck Sharp and Dohme (MSD) recombinant DNA vaccine (rDNAV) were given to 318 children who had received age appropriate doses of MSD plasma derived vaccine (PDV) five years earlier. Sera were tested for hepatitis B virus (HBV) seromarkers pre- and postbooster. RESULTS: all children who had responsed to primary immunisation demonstrated an anamnestic response. The geometric mean titre (GMT) of antibody to hepatitis B surface antigen (antiHBs) rose from 89 to 4777 IU/L. AntiHBs was detected in 94% of vaccinees just prior to the five year booster, and 96.5% a mean of 10 days later. CONCLUSION: when initial vaccine seroconversion is satisfactory, protection of responders persists for at least five years, assuming that the response to vaccine boosters mimics the response to wild virus. Therefore, for population control of hepatitis B in children in endemic areas, booster doses are not required for at least five years.

Antibodies, Viral↗
PubMed1992

Recovery metabolism of trout white muscle: role of mitochondria.

Recovery from burst exercise in fish is very slow. Lactate conversion to glycogen occurs primarily within white muscle and must be fueled by mitochondrially produced ATP. In a parallel study we characterized the changes in tissue metabolites associated with burst exercise and recovery in rainbow trout (Oncorhynchus mykiss) white muscle. The present study examines whether the mitochondrial capacity to produce ATP may limit the rate of recovery of trout white muscle. The cost (ATP.min-1.g-1) of glycogen resynthesis (0.05 mumol lactate converted.min-1.g tissue-1) was compared with the mitochondrial capacity to produce ATP. The cost of recovery can be met by only 3.5% of the maximal mitochondrial capacity. In fact, during recovery trout white muscle mitochondria operate at a small fraction of their in vitro maximum. This capacity is suppressed in vivo by highly inhibitory ATP/ADP and limiting phosphate. The primary signal for increased ATP synthesis associated with recovery is not a change in ATP/ADP but probably phosphate, elevated because of phosphocreatine hydrolysis and adenylate catabolism in the purine nucleotide cycle. At low ADP availability and suboptimal phosphate (less than 5 mM), acidosis enhances respiration. At high respiratory rates mitochondrial pyruvate oxidation is sensitive to pyruvate concentration over the physiological range (apparent Michaelis constant = 35-40 microM). This sensitivity is lost at the low rates that approximate in vivo respiration. Changes in lactate do not affect the kinetics of pyruvate oxidation. Fatty acid oxidation may spare pyruvate and lactate for use in glyconeogenesis, primarily through allosteric inhibition of pyruvate dehydrogenase rather than covalent modification.

Adenosine Diphosphate↗
PubMed1992

Integrating metabolic pathways in post-exercise recovery of white muscle.

Purine nucleotides (ATP, ADP, AMP, IMP), creatine, phosphocreatine, lactate, pyruvate and glycogen were measured in rainbow trout (Oncorhynchus mykiss) white muscle following exercise to exhaustion. Estimates of intracellular pH permitted calculation of free concentrations of nucleotides ([nucleotide]f) required for most models of control of energy metabolism. Creatine charge, [PCr]/([PCr]+[Cr]), fell from 0.49 +/- 0.05 (mean +/- S.E.M.) to 0.08 +/- 0.02 with exercise but recovered completely by the first sample (2 h). Although [ATP] declined to 24% of resting levels and recovered very slowly, RATP, [ATP]/([ATP]+[ADP]f+[AMP]f), and energy charge, EC, ([ATP]+0.5[ADP]f)/([ATP]+[ADP]f+[AMP]f), recovered as quickly as creatine charge. Changes in [IMP] mirrored those in [ATP], suggesting that AMP deaminase is responsible for maintaining RATP and EC. Recovery of carbon status was much slower than recovery of energy status. Lactate increased from 4 mumol g-1 at rest to 40 mumol g-1 at exhaustion and did not recover for more than 8 h. Glycogen depletion and resynthesis followed a similar time course. During the early stages of recovery, calculated [ADP]f declined by more than 10-fold relative to the resting values. The resulting high [ATP]/[ADP]f ratios may limit the rate at which white muscle mitochondria can produce ATP to fuel glycogenesis in situ. It is postulated that the high [ATP]/[ADP]f ratios are required to drive pyruvate kinase in the reverse direction for glyconeogenesis in recovery.

Adenine Nucleotides↗
PubMed1991

Peroxisomal beta-oxidation: insights from comparative biochemistry.

The activities of fatty acyl-CoA oxidase (FAO) and carnitine palmitoyl transferase (CPT), indices of the capacities of peroxisomal beta-oxidation and mitochondrial beta-oxidation, respectively, were determined in livers of several vertebrate species notable for differences in dietary fatty acid composition. In suckling rats FAO activities were half that in adult rats and CPT/FAO ratios twice that of adult rats. As their milk diet is dominated by medium chain fatty acids, this observation is consistent with current ideas about the role of peroxisomal beta-oxidation in rat liver in oxidation of long chain unsaturated fatty acids. In nectar-feeding hummingbirds (fatty acids synthesized de novo) FAO activities were 50% greater than adult rats and CPT/FAO ratios one-third less than adult rats, suggesting that peroxisomal beta-oxidation is relatively more important in this species, despite a fatty-acid-poor diet. In marine fish (herring, dogfish shark, hagfish) FAO activities were all less than 15% that of rats and undetectable in hagfish. CPT/FAO ratios were greater in herring (8.1) and hagfish (greater than 30) than adult rats (3.1), suggesting that peroxisomal beta-oxidation is relatively less important in these species despite a natural diet containing high levels of long chain polyunsaturated fatty acids. These data are discussed in relation to current ideas about the role of peroxisomes in beta-oxidation of fatty acids.

Acyl-CoA Oxidase↗
PubMed1990

Hepatitis B vaccine boosters: further studies in children.

Two groups of children were given reduced dose boosters with Merck Sharp and Dohme (MSD) recombinant DNa, yeast derived hepatitis B vaccine (YDV), 30 and 34 months respectively after primary immunisation with MSD plasma derived vaccine (PDV). In the first group of unselected children the geometric mean titre (GMT) rose from 387 to 8346 IU/L, with all children protected. The second group were selected as the poorest responders to their primary course of vaccine. The booster raised the GMT from 14.6 to 325 IU/L, with 95% having protective levels of anti-HBs (greater than 10 IU/L). This study confirms that the vaccine used by the New Zealand Department of Health for the hepatitis B immunisation programme in preschoolers, will provide protection for the great majority of children for at least three years.

Adolescent↗
PubMed1990

Injuries to child cyclists in the Bay of Plenty.

Over five years 415 children attended the accident and emergency department at Whakatane Hospital for injuries sustained while riding pedal cycles, four of whom died and 17% required admission to hospital. Twenty-eight percent of riders were less than eight years old, although it is known that children are not safe on roads up to this age. Forty-five children were passengers, mostly under five years of age and suffering from lower limb injuries from catching feet in wheel spokes. BMX bicycle riders were overrepresented among the injured. All deaths and permanent incapacity were a result of brain damage and could probably have been prevented by the use of approved safety helmets. There is a clear need for communities to address these safety issues.

Accidents↗
PubMed1990

Very low dose hepatitis B vaccination in the newborn: anamnestic response to booster at four years.

Seventy-eight children who had received three very low doses (1 or 2 microg) of Merck, Sharp and Dohme (MSD) plasma-derived vaccine (PDV) in early infancy were followed to approximately four years of age. Of the 70 who had responded to the initial course of vaccine with measurable anti-HBs, levels had fallen to below 10 mlU/ml in 38% of subjects given 1 microg doses and in 17% of those who had been given 2 microg doses. None of the children were positive for anti-HBc. Two weeks after 2 microg dose of MSD recombinant DNA (rDNA) vaccine all subjects had more than 10 mlU/ml of anti-HBs, with 90% exceeding 1,000 mlU/ml. A response to hepatitis B vaccine in infancy is followed by an effective immunological memory for several years, even if anti-HBs falls to low levels. The rDNA hepatitis B vaccine (MSD) in 2 microg doses is an effective booster following a primary course of plasma derived vaccine.

Child, Preschool↗
PubMed1990

Fuel selection in rufous hummingbirds: ecological implications of metabolic biochemistry.

Hummingbirds in flight display the highest rates of aerobic metabolism known among vertebrates. Their flight muscles possess sufficient maximal activities of hexokinase and carnitine palmitoyltransferase to allow the exclusive use of either glucose or long-chain fatty acids as metabolic fuels during flight. Respiratory quotients (RQ = VCO2/VO2) indicate that fatty acid oxidation serves as the primary energy source in fasted resting birds, while subsequent foraging occurs with a rapid shift towards the use of carbohydrate as the metabolic fuel. We suggest that hummingbirds building up fat deposits in preparation for migration behave as carbohydrate maximizers (or fat minimizers) with respect to the metabolic fuels selected to power foraging flight.

Animals↗
PubMed1990

Mitochondrial and peroxisomal fatty acid oxidation in elasmobranchs.

In heart and red muscle of dogfish (Squalus acanthias), the maximal activities of the fatty acid catabolizing enzyme carnitine palmitoyltransferase (CPT) are less than 5% the rate in the same tissues of teleosts (carp, Cyprinus carpio; trout, Salmo gairdneri). CPT activities in these tissues of hagfish (Eptatretus stouti) are approximately 10% the rate in teleosts. However, the maximal activities of the beta-oxidation enzyme beta-hydroxyacyl-CoA dehydrogenase (HOAD) in dogfish red muscle and heart are similar to these tissues in the other species. This paradox prompted a more detailed study on the capacity of mitochondria from dogfish cardiac and red skeletal muscles to utilize fatty acids, possibly by a CPT-independent pathway. Free fatty acids were not oxidized by mitochondria from red muscle (hexanoate, octanoate, decanoate, and palmitate) or from heart (octanoate, palmitate). Neither hyposmotic incubation nor addition of 5 mM ATP could stimulate oxidation of octanoate or palmitate in either preparation, suggesting that these tissues have little capacity to oxidize fatty acids by a carnitine-independent pathway. Palmitoyl carnitine oxidation was detectable at very low rates in these mitochondria only with hyposmotic incubation. Octanoyl carnitine was oxidized at greater rates than palmitoyl carnitine, 10% the rate of pyruvate in both tissues, suggesting that medium-chain fatty acids could be physiologically relevant fuels in elasmobranchs if available to heart and red muscle. One potential source of medium-chain fatty acids is hepatic peroxisomal beta-oxidation, which occurs in dogfish liver at maximal activities similar to carp and trout liver. However, based on relative rates of oxidation, it is likely that dogfish heart and red muscle metabolism are fueled primarily by carbohydrate and ketone bodies.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1989

Mass vaccination against hepatitis B in preschool children: immunogenicity after three reduced doses.

The immunising effect of three reduced doses of Merck Sharp and Dohme (MSD) H-B Vax plasma derived vaccine delivered at monthly intervals was evaluated in 1225 four year old children. Eighteen children had evidence of previous or current infection with HBV. Of the remaining 1207 children, 1186 (98.3%) had antibody to hepatitis B surface antigen (anti-HBs) when tested by enzyme immunoassay (EIA). Levels of anti-HBs in 96 randomly selected sera were independently quantitated by radioimmunoassay (RIA) and all were positive for anti-HBs, with a geometric mean titre of 1013. There was no significant difference in seroconversion or anti-HBs levels between the groups of children nationwide. In 19 of the 39 centres, seroconversion was 100%. No centre had less than 92% seroconversion. This study confirms that three 2 microgram doses of MSD H-B Vax plasma derived vaccine given intramuscularly (IM) at monthly intervals are highly immunogenic in this paediatric population.

Child, Preschool↗
PubMed1989

Liver disease and hepatitis B infection in a large New Zealand family.

This study illustrates the relationship between the hepatitis B virus (HBV) carrier state and primary hepatocellular carcinoma in a large family of Maori (173 members) amongst whom four brothers have died of primary hepatocellular carcinoma. The brothers were from a generation of fourteen siblings, eleven of whom were tested for hepatitis B surface antigen (HBsAg) and all found to be positive. Amongst the offspring of this generation there were 13 HBsAg positives from 28 children (46%) born to female carriers but no HBsAg positives amongst the 28 offspring of male carriers. The study provides further evidence that the morbidity which often follows HBsAg carriage, may be associated with early (perinatal) infection. There was a marked decrease in HBV serologic markers in succeeding generations, from 100% in generation two, to 55% in generation three and 14% in generation four, unrelated to the use of hepatitis B vaccine.

Adult↗
PubMed1989

Oxidative properties of carp red and white muscle.

Substrate preferences of isolated mitochondria and maximal enzyme activities were used to assess the oxidative capacities of red muscle (RM) and white muscle (WM) of carp (Cyprinus carpio). A 14-fold higher activity of citrate synthase (CS) in RM reflects the higher mitochondrial density in this tissue. RM mitochondria oxidize pyruvate and fatty acyl carnitines (8:O, 12:O, 16:O) at similarly high rates. WM mitochondria oxidize these fatty acyl carnitines at 35-70% the rate of pyruvate, depending on chain length. WM has only half the carnitine palmitoyl transferase/CS ratio of RM, but similar ratios of beta-hydroxyacyl CoA dehydrogenase/CS. Ketone bodies are poor substrates for mitochondria from both tissues. In both tissues mitochondrial alpha-glycerophosphate oxidation was minimal, and alpha-glycerophosphate dehydrogenase was present at low activities, suggesting the alpha-glycerophosphate shuttle is of minor significance in maintaining cytosolic redox balance in either tissue. The mitochondrial oxidation rates of other substrates relative to pyruvate are as follows: alpha-ketoglutarate 90% (RM and WM); glutamate 45% (WM) and 70% (RM); proline 20% (WM) and 45% (RM). Oxidation of neutral amino acids (serine, glycine, alanine, beta-alanine) was not consistently detectable. These data suggest that RM and WM differ in mitochondrial properties as well as mitochondrial abundance. Whereas RM mitochondria appear to be able to utilize a wide range of metabolic fuels (fatty acids, pyruvate, amino acids but not ketone bodies), WM mitochondria appear to be specialized to use pyruvate.

Animals↗