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Biomedical subjects

B W Young

Publications and source records attributed to B W Young.

At least 19 recordsLinked to original sources
PubMed2002

Monotropa uniflora: morphological and molecular assessment of mycorrhizae retrieved from sites in the sub-boreal spruce biogeoclimatic zone in central British Columbia.

Plant species in the subfamily Monotropoideae are achlorophyllous and have developed a complex mode of nutrition, receiving photosynthates from neighboring trees via shared fungi. To explore the mycorrhizal associations of Monotropa uniflora in central British Columbia (B.C.), plants were sampled from three sites: a Betula-dominated site and two sites with a mixture of conifer and hardwood trees. Fifteen M. uniflora root-clusters were sampled (five per site) and the mycorrhizal diversity was assessed using morphological and molecular (PCR-RFLP analysis and DNA sequencing) methods. Both methods showed that root-clusters (often comprising several hundred mycorrhizal tips) belonging to the same plant appeared to involve fungus monocultures in the family Russulaceae. All mycorrhizae exhibited typical Russula morphology and had mantle cystidia. Two root-clusters, one each from sites 1 and 3, lacked one of the two types of cystidia present on all other root-clusters. PCR-RFLP analysis resulted in three fragment patterns for the 15 root clusters. One molecular fragment pattern included the two root-clusters displaying the single cystidium type plus an additional root-cluster with both cystidia types. DNA sequencing of a portion of the ITS2 region of the ribosomal DNA suggests that the three variants represent different species; two of the variants clustered with the hypogeous fungi Martellia and Gymnomyces. The study provides increased evidence of low diversity and high specificity in the Monotropa-fungus relationship and suggests that M. uniflora associates uniquely with fungi in the family Russulaceae in central B.C.

British Columbia↗
PubMed2001

Prediction of hyperbilirubinemia in near-term and term infants.

OBJECTIVE: The purpose of this study was to determine whether end-tidal carbon monoxide (CO) corrected for ambient CO (ETCOc), as a single measurement or in combination with serum total bilirubin (STB) measurements, can predict the development of hyperbilirubinemia during the first 7 days of life. METHODS: From nine multinational clinical sites, 1370 neonates completed this cohort study from February 20, 1998 through February 22, 1999. Measurements of both ETCOc and STB were performed at 30+/-6 hours of life; STB also was measured at 96+/-12 hours and subsequently following a flow diagram based on a table of hours of age-specific STB. An infant was defined as hyperbilirubinemic if the hours of age-specific STB was greater than or equal to the 95th percentile as defined by the table at any time during the study. RESULTS: A total of 120 (8.8%) of the enrolled infants became hyperbilirubinemic. Mean STB in breast-fed infants was 8.92+/-4.37 mg/dl at 96 hours versus 7.63+/-3.58 mg/dl in those fed formula only. The mean ETCOc at 30+/-6 hours for the total population was 1.48+/-0.49 ppm, whereas those of nonhyperbilirubinemic and hyperbilirubinemic infants were 1.45+/-0.47 and 1.81+/-0.59 ppm, respectively. Seventy-six percent (92 of 120) of hyperbilirubinemic infants had ETCOc greater than the population mean. An ETCOc greater than the population mean at 30+/-6 hours yielded a 13.0% positive predictive value (PPV) and a 95.8% negative predictive value (NPV) for STB > or =95th percentile. When infants with STB > or =95th percentile at <36 hours of age were excluded, the STB at 30+/-6 hours yielded a 16.7% PPV and a 98.1% NPV for STB >75th percentile. The combination of these two measurements at 30+/-6 hours (either ETCOc more than the population mean or STB >75th percentile) had a 6.4% PPV with a 99.0% NPV. CONCLUSIONS: This prospective cohort study supports previous observations that measuring STB before discharge may provide some assistance in predicting an infant's risk for developing hyperbilirubinemia. The addition of an ETCOc measurement provides insight into the processes that contribute to the condition but does not materially improve the predictive ability of an hours of age-specific STB in this study population. The combination of STB and ETCOc as early as 30+/-6 hours may identify infants with increased bilirubin production (eg, hemolysis) or decreased elimination (conjugation defects) as well as infants who require early follow-up after discharge for jaundice or other clinical problems such as late anemia. Depending on the incidence of hyperbilirubinemia within an institution, the criteria for decision making should vary according to its unique population.

Bilirubin↗
PubMed2001

Prediction of hyperbilirubinemia in near-term and term infants.

OBJECTIVE: The purpose of this study was to determine whether end-tidal carbon monoxide (CO) corrected for ambient CO (ETCOc), as a single measurement or in combination with serum total bilirubin (STB) measurements, can predict the development of hyperbilirubinemia during the first 7 days of life. METHODS: From 9 multinational clinical sites, 1370 neonates completed this cohort study from February 20, 1998, through February 22, 1999. Measurements of both ETCOc and STB were performed at 30 +/- 6 hours of life; STB also was measured at 96 +/- 12 hours and subsequently following a flow diagram based on a table of hours of age-specific STB. An infant was defined as hyperbilirubinemic if the hours of age-specific STB was greater than or equal to the 95th percentile as defined by the table at any time during the study. RESULTS: A total of 120 (8.8%) of the enrolled infants became hyperbilirubinemic. Mean STB in breastfed infants was 8.92 +/- 4.37 mg/dL at 96 hours versus 7.63 +/- 3.58 mg/dL in those fed formula only. The mean ETCOc at 30 +/- 6 hours for the total population was 1.48 +/- 0.49 ppm, whereas those of nonhyperbilirubinemic and hyperbilirubinemic infants were 1.45 +/- 0.47 ppm and 1.81 +/- 0.59 ppm, respectively. Seventy-six percent (92 of 120) of hyperbilirubinemic infants had ETCOc greater than the population mean. An ETCOc greater than the population mean at 30 +/- 6 hours yielded a 13.0% positive predictive value (PPV) and a 95.8% negative predictive value (NPV) for STB >/=95th percentile. When infants with STB >95th percentile at <36 hours of age were excluded, the STB at 30 +/- 6 hours yielded a 16.7% PPV and a 98.1% NPV for STB >75th percentile. The combination of these 2 measurements at 30 +/- 6 hours (either ETCOc more than the population mean or STB >75th percentile) had a 6.4% PPV with a 99.0% NPV. Conclusions. This prospective cohort study supports previous observations that measuring STB before discharge may provide some assistance in predicting an infant's risk for developing hyperbilirubinemia. The addition of an ETCOc measurement provides insight into the processes that contribute to the condition but does not materially improve the predictive ability of an hours of age-specific STB in this study population. The combination of STB and ETCOc as early as 30 +/- 6 hours may identify infants with increased bilirubin production (eg, hemolysis) or decreased elimination (conjugation defects) as well as infants who require early follow-up after discharge for jaundice or other clinical problems such as late anemia. Depending on the incidence of hyperbilirubinemia within an institution, the criteria for decision making should vary according to its unique population.

Bilirubin↗
PubMed2000

Effects of low doses of caffeine on aggressive behavior of male rats.

To date, the effect of low doses of caffeine on aggression has not been systematically examined. Doses of caffeine greater than 30 mg/kg appear to reduce social interaction and aggression in all species studied. In a double blind study of the effects of low doses of caffeine on aggression, rats were housed four per cage, and aggressive behavior against an intruder was recorded during baseline and following administration of 2.5, 5, 10, and 20 mg/kg caffeine. Aggressive behavior was significantly increased following administration of the higher doses of caffeine. Doses of 5, 10, and 20 mg/kg caffeine all were effective in increasing pushing behavior, whereas doses of 5 and 10 mg/kg were most effective in increasing boxing behavior, and a dose of 10 mg/kg was significantly more effective than other doses in increasing chasing and roll-tumble-bite behaviors. Based on these results and other published reports, the inverted-U shaped dose-dependent effect of caffeine on aggression appears to apply, with aggressive behavior being most elevated following doses of 5-20 mg/kg caffeine, less elevated following 2.5 mg/kg or 30 mg/kg, and significantly reduced with doses above 40 mg/kg and at doses below 2.5 mg/kg.

Aggression↗
PubMed1995

A reduced dose approach to hepatitis B vaccination for low-risk newborns and preschool children.

The effectiveness of a 2.5 micrograms dose of the hepatitis B vaccine (B-Hepavac II) was compared with that of 5 micrograms in 587 low-risk neonates and 777 preschool children of age 3-8 years. The vaccines were administered at months 0, 1 and 3, with postvaccination serology tested at months 4 and 12. The seroconversion rates of the 2.5 microgram recipients (newborn: 93.5%; preschool children: 97.4%) are comparable with the 5 micrograms group (newborn: 95.7%; preschool children: 98.7%). The seroconversion rates of the newborns are, however, significantly lower in the 2.5 micrograms group if positive response is taken as a titre > 10 IU l-1, instead of > 0 IU l-1. The older children, on the other hand, achieved a higher seroconversion rate and geometric mean titre (GMT) when compared with the newborns. irrespective of the dose received.

Child, Preschool↗
PubMed1985

Uptake and incorporation of choline by Schistosoma mansoni adults.

Choline uptake and incorporation into Schistosoma mansoni is used as a model for investigating transport across and formation of a double bilayer surface of a syncytial transporting epithelium. Choline uptake reached a maximal rate during the first 2 min (Vmax = 0.27 mumol mg-1 protein min-1; Km = 36 microM). Choline uptake during a 30 min incubation was similar to that of single bilayer transport systems described in the literature. Choline incorporation into phosphatidylcholine was saturated above 40 microM external choline concentration (Vmax = 3.7 pmol mg-1 protein min-1; Km = 7 microM). The low rate of choline efflux and the half life of the tissue choline pool (T 1/2 = 3 h), suggests that free choline pools available for efflux in S. mansoni are small. This model allows the determination of whether a proposed effector of membrane phosphatidylcholine synthesis and turnover alters surface bilayer formation through changes in transport of the precursor across the apical surface.

Animals↗
PubMed1984

Hormonal and pharmacologic agents affecting choline uptake and incorporation in Schistosoma mansoni adults.

Initial uptake of choline by Schistosoma mansoni (2-min uptake) revealed no differences between male, female or paired worms for any of the control or experimental groups. After a 30-min uptake period, however, males showed significantly higher uptake of choline in the presence of mitomycin C, cytochalasin B and calcium ionophore A23187, while paired worms showed significantly reduced uptake in the presence of actinomycin D, puromycin, mitomycin C, cytochalasin B, colchicine, insulin, thyroxine and lysine. Choline uptake by females was elevated, in the presence of cytochalasin B at 30 min, although not significantly. Significantly increased incorporation of choline into phosphatidylcholine was observed following a 30-min incubation with 5-hydroxytryptamine (males), puromycin and thyroxine (females) and calcium ionophore A23187 (males, females and pairs). These effects on phosphatidylcholine synthesis are discussed in relation to the uptake data and to previous work concerning the outer membrane complex of the parasite as an important facet of parasite resistance to the host immune response.

Animals↗
PubMed1984

Serum factors affecting choline uptake and incorporation in Schistosoma mansoni adults.

Uptake and incorporation of choline into adult Schistosoma mansoni was examined in the presence of serum from known permissive and non-permissive hosts. Uptake of choline was not significantly different for paired, male or female worms in any one treatment. The presence of serum from uninfected rat, hamster and human sources and from infected rat and hamster sources did not significantly affect choline uptake. Heat-inactivation of these sera before addition to the culture medium also had no effect on choline uptake. The incorporation of choline into phosphatidylcholine appeared similar in all of the sera until 30-min incubation at which point some significant differences could be demonstrated. Increased incorporation could be shown with the addition of serum from uninfected rat, hamster and human sources. Heat-inactivation of these sera abrogated this effect. The stimulation of choline incorporation into phosphatidylcholine is discussed in relation to the heat labile components of serum. Host permissiveness to infection did not alter choline uptake or incorporation into phosphatidylcholine.

Animals↗
PubMed1983

The influence of dietary iron and molybdenum on copper metabolism in calves.

1. Twenty heifer calves were allocated to four groups and maintained for 32 weeks on a diet based mainly on barley and straw and containing 4 mg copper/kg. The diet was supplemented with 0 or 800 mg iron/kg and 0 or 5 mg molybdenum/kg. 2. Liver and plasma Cu concentrations, erythrocyte superoxide dismutase (EC 1.15.1.1) and plasma caeruloplasmin (EC 1.16.3.1) activities decreased greatly and rapidly in all calves given the Fe or Mo supplements or both. Levels indicative of severe Cu deficiency were attained within 16 weeks. There were no significant differences in values in animals given Fe, Mo or Fe plus Mo. 3. Clinical signs of Cu deficiency developed after 20 weeks in the calves given the Mo supplement. Growth rates were reduced, skeletal lesions developed and hair texture and colour were affected. No such effects were observed in the calves given only the Fe supplement. 4. Plasma and liver Fe concentrations increased in calves given the Fe supplement but were not greatly affected by Mo, even when the calves were severely Cu-deficient. 5. The significance of the effects of Fe and Mo on Cu metabolism are discussed with special regard to the influence of soil ingestion on Cu availability and to the frequent lack of correlation between the Cu status of animals and their clinical condition.

Animals↗
PubMed1982

Major phospholipids and phosphatidylcholine synthesis in adult Schistosoma mansoni.

The major phospholipids present in the phospholipid extract of Schistosoma Mansoni were phosphatidylcholine (28%), phosphatidylethanolamine 925%), phosphatidylserine (15%) and phosphatidylglycerol (8%). The synthesis of phosphatidylcholine in S. mansoni adults occurred by the choline to phosphatidylcholine of worm slices appeared linear over time with no demonstrable sex differences in choline incorporation. A slight difference in the incorporation of CDPcholine by separate sexes was evident. Methylation phosphatidylethanolamine to phosphatidylcholine could not be demonstrated.

Animals↗
PubMed1982

Copper metabolism in rats given di- or trithiomolybdates.

As one of a series of studies on the influence of S substitution of MoO4(2-) on the action of Mo as an antagonist of Cu, the effects of MoO2S2(2-) and MoOS3(2-) on the metabolism of Cu by rats have been investigated. Administration of either oxythiomolybdate increased both plasma Cu concentration and the retention of Cu by the albumin fraction of plasma. In contrast to the effects of MoS4(2-), described previously, neither oxythiomolybdate inhibited 64Cu absorption from the digestive tract or induced biochemical or clinical signs of Cu deficiency. Evidence is discussed suggesting that the potency of the thio- and oxythiomolybdates as inhibitors of Cu utilization is directly proportional to the degree of thio substitution within the series series MoO4- chi S chi 2-.

Animals↗
PubMed1982

Effects of tetrathiotungstate and dithiotungstate on copper metabolism in rats.

The effects of dietary supplementation with ammonium tetrathiotungstate and dithiotungstate on copper metabolism in young rats have been investigated. The addition of WS4(2-) (4-32 mg W/kg diet) decreased growth rates and induced clinical and biochemical signs of Cu deficiency. These were overcome by increasing the dietary content of Cu. The intestinal absorption of 64Cu was impaired and the tissue distribution of absorbed Cu modified by the administration of WS4(2-). No clinical or biochemical defects indicative of Cu deficiency developed in rats receiving WO2S2(2-) in their diet at concentrations up to 32 mg W/kg. In contrast, this oxythioanion enhanced the content of Cu in plasma liver and kidney, especially when dietary Cu was increased. Most of the additional Cu retained by plasma and kidney was associated with albumin and metallothionein, respectively. The effects of these W sources are compared with those caused by their thio- and oxythiomolybdate analogs and are discussed in relation to the mechanisms whereby Mo induces Cy deficiency in ruminants.

Animals↗
PubMed1981

The effects of age, sex, and zinc status on the accumulation of (copper, zinc)- metallothionein in rat kidneys.

A study has been made of the distribution of copper in the kidneys of growing rats. Renal copper concentrations increased steadily with age and were greater in female than in male animals. Most of the copper was present as (copper, zinc)-metallothionein and two forms of this protein were isolated and characterized from the kidneys of mature female rats. That copper metabolism in kidneys is subject to hormonal influence was indicated by a reduction in the concentrations of copper and (copper, zinc)-metallothionein in ovariectomized rats and by an increase in their concentrations after the administration of progesterone. Concentrations of renal (copper, zinc)-metallothionein were less in zinc-deficient than zinc-adequate rats during pregnancy and after progesterone administration.

Age Factors↗