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P Dick

Publications and source records attributed to P Dick.

At least 37 records · Page 2Linked to original sources
PubMed1999

Infrared Spectroscopic Characterization of the Alumina Surface.

Infrared spectra of Cr(CO)6 adsorbed at different surface centers on gamma-alumina were investigated. The spectra of the probe complex revealed the existence of three types of strong Lewis centers and that of physisorbed Cr(CO)6. In the case of the physisorbed complex Oh symmetry was widely conserved, and addition to strong Lewis centers led to lowering of the symmetry. The assumption of C4v symmetry, caused by interaction of one CO group of the complex with a Lewis center, may explain the spectra. Approximate values for the integral extinction coefficients were determined. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Infrared Spectroscopic Characterization of the Alumina Surface.

Using IR spectroscopic data of Cr(CO)6 adsorbed on different surface centers on gamma-Al2O3, we were able to calculate isotherms for adsorption on these centers. Linear relations were observed between spectroscopic data (position, extinction coefficient, and half-width values) of corresponding bands of Cr(CO)6, adsorbed on different Lewis acid centers and the free enthalpy of adsorption. Thus it is possible to determine DeltaG degreesad values for different centers from one adsorption measurement and thus to characterize the Lewis acid strength of the centers. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Effect of prepartum administration of monensin in a controlled-release capsule on milk production and milk components in early lactation.

Dry cows and pregnant heifers from 25 farms near Guelph, Ontario, Canada were enrolled in a large double-blind, randomized clinical trial that was designed to evaluate the impact of monensin on energy metabolism, health, and production. A total of 503 cows was given monensin in controlled-release capsules, and 507 were administered placebo capsules 3 wk prior to the expected calving date. The effects of treatment on milk production and milk components at the first three Dairy Herd Improvement (DHI) tests were evaluated using repeated measures analysis of variance. Treatment with monensin increased milk production, but this effect was dependent on body condition score prior to calving. Cows that were classified as thin (score of < or = 3.0) did not have increased production in response to monensin treatment. Cows with fair body condition (score of 3.25 to 3.75) produced significantly more milk at the second DHI test (+0.85 kg), but cows that were fat (score of > or = 4.0) produced significantly more milk than did controls for all three DHI tests (+1.25 kg) in early lactation. Monensin significantly increased projected 305-d milk production in cows from herds at increased risk of ketosis. Treatment with monensin had no significant effect on either milk fat percentage or milk protein percentage.

Animals↗
PubMed1999

The impact of a monensin controlled-release capsule on subclinical ketosis in the transition dairy cow.

An experiment was designed to examine subclinical ketosis in periparturient dairy cows and the antiketogenic effects of monensin. Subclinical ketosis was induced through a 10% feed restriction and was quantitatively determined using a blood beta-hydroxybutyrate (BHBA) threshold of 1200 mumol/L. Monensin decreased the BHBA concentration by 35% and increased the glucose concentration by 15%. No effect of monensin on milk production was detected, but rumen fermentation was altered. Monensin decreased the acetate to propionate ratio, decreased the butyrate concentration, and increased pH. The lower concentration of BHBA in blood and higher concentration of blood glucose in cows treated with a monensin controlled-release capsule decreased subclinical ketosis in early lactation cows.

3-Hydroxybutyric Acid↗
PubMed1999

Effect of a monensin-controlled release capsule on cow health and reproductive performance.

Dry cows and pregnant heifers from 25 farms near Guelph, Ontario, Canada were enrolled in a large, double-blind, randomized clinical trial designed to evaluate the impact of monensin on energy metabolism, health, and production. A total of 503 cows was given monensin in controlled-release capsules, and 507 cows were administered placebo capsules 3 wk before expected calving date. The effects of treatment on health were evaluated using a logistic regression model. Treatment with monensin significantly reduced the incidence of abomasal displacement (OR = 0.41-0.84) and multiple illnesses (OR = 0.38-0.89). Monensin treatment tended to reduce the incidence of clinical ketosis (P = 0.11) and the risk of being culled (P = 0.09) in the first 94 d of lactation. Reproductive performance was analyzed with both a logistic regression model for conception rate and a survival analysis for days to first breeding and days from calving to conception. Treatment with monensin had no significant effect on any measure of reproductive performance.

Abomasum↗
PubMed1998

Is bone marrow aspiration needed in acute childhood idiopathic thrombocytopenic purpura to rule out leukemia?

OBJECTIVE: To assess the prevalence of leukemia in a series of bone marrow aspiration (BMA) samples collected to confirm provisional diagnoses of acute idiopathic thrombocytopenic purpura (ITP) in children. DESIGN: A retrospective cohort. SETTING: All BMA reports at The Hospital for Sick Children, Toronto, Ontario (a tertiary care pediatric hospital), from January 1, 1984, to May 31, 1996, were reviewed. PATIENTS: Included were BMAs performed to confirm provisional diagnoses of ITP in children (6 months to 18 years of age) with "typical" contemporaneous hematologic features of ITP (platelet count, < or =50 x 10(9)/L; hemoglobin level, > or =100 g/L [6-12 months of age] or > or =110 g/L [> 1 year of age]; white blood cell count, > or =5 x 10(9)/L [6 months to 6 years of age] or > or =4 x 10(9)/L [> 6 years of age]; and neutrophil count, > or =1.5 x 10(9)/L [6 months to 6 years of age] or > or =2 x 10(9)/L [> 6 years of age]). Children with chronic ITP, thrombocytopenia-related chronic conditions, or leukemic blasts on peripheral smears were excluded. MAIN OUTCOME MEASURE: The finding of leukemia in the BMA report was chosen a priori as the primary outcome for the yield of BMA. RESULTS: Four hundred eighty-four BMAs were performed to confirm provisional diagnoses of acute childhood ITP. No diagnoses of leukemia were revealed in the 332 children with typical hematologic features of ITP. The risk of missing the diagnosis of leukemia in this setting is less than 1%. CONCLUSIONS: The yield of BMA for leukemia in this setting is low. Routine BMA is not necessary for children with typical acute ITP.

Adolescent↗
PubMed1998

Effect of prepartum administration of monensin in a controlled-release capsule on postpartum energy indicators in lactating dairy cows.

The effects of monensin on the energy metabolism of dairy cows in early lactation were investigated in a large clinical trial that was randomized and double-blinded. A total of 1010 Holstein cows and first lactation heifers were allocated to receive a controlled-release capsule of monensin or a placebo at 3 wk prior to expected calving date. Treatments were randomized across 25 dairy farms located near Guelph, Ontario, Canada. Serum samples obtained at the time of treatment administration and at wk 1, 2, 3, 6, and 9 postcalving were analyzed for beta-hydroxybutyrate, glucose, aspartate aminotransferase, urea, total protein, calcium, and phosphorus. Cows were also assigned a body condition score at the time each sample was obtained. Monensin treatment significantly reduced serum beta-hydroxy-butyrate concentrations at wk 1, 2, and 3 postpartum and significantly raised serum glucose concentrations during wk 1 and 2 of lactation. In addition, monensin treatment significantly reduced the loss of body condition score and decreased serum activity of aspartate aminotransferase during the postpartum period. Concentrations of serum urea were significantly higher during wk 2 and 3 postpartum for the cows that were treated with monensin. Monensin treatment had no effect on the concentrations of calcium, phosphorus, or total protein.

3-Hydroxybutyric Acid↗
PubMed1998

Efficacy of monensin for the prevention of subclinical ketosis in lactating dairy cows.

A total of 1010 dry cows and pregnant heifers was randomly selected from 25 dairy farms near Guelph, Ontario, Canada to receive either a controlled-release capsule of monensin or a placebo at 3 wk prior to expected calving. Serum samples were obtained at the time of treatment administration, and both serum and milk samples were collected at wk 1, 2, 3, 6, and 9 postcalving. The threshold used to define subclinical ketosis was selected a priori at a concentration of > or = 1200 mumol/L of beta-hydroxybutyrate. Using this threshold, the prevalence and incidence of subclinical ketosis were significantly reduced (50%) by monensin treatment. The duration of subclinical ketosis for cows that had been treated with monensin was also shorter than that for cows treated with the placebo. Monensin treatment significantly reduced the incidence of subclinical ketosis when the threshold was defined using higher concentrations of serum beta-hydroxybutyrate (1400 and 2000 mumol/L). In addition, monensin significantly reduced the prevalence of positive milk ketone tests.

3-Hydroxybutyric Acid↗
PubMed1998

Anti-inflammatory benefits of tilmicosin in calves with Pasteurella haemolytica-infected lungs.

OBJECTIVES: To determine whether tilmicosin alters neutrophil infiltration or function, induces neutrophil apoptosis, and affects accumulation of leukotriene B4 (LTB4) or tumor necrosis factor-alpha (TNF-alpha) in lungs of calves experimentally infected with Pasteurella haemolytica. ANIMALS: 12 weight-ranked Holstein calves. PROCEDURE: Calves were given 25% propylene glycol vehicle (n = 5) or tilmicosin (10 mg/kg of body weight; n = 6) subcutaneously, 18 hours and 15 minutes before intratracheal infection with 2 x 10(8) P haemolytica organisms. Two unmanipulated calves served as controls in some experiments. Rectal temperatures were recorded 15 minutes before, and at 3-hour intervals after infection for 24 hours. Samples obtained from bronchoalveolar lavage performed 3 and 24 hours after infection were used to assess colonization by P haemolytica, and neutrophil infiltration. Neutrophil phagocytosis of P haemolytica, membrane leakage as determined by trypan blue exclusion, oxidative function as determined by nitro blue tetrazolium reduction, and apoptosis, using electron microscopy and DNA fragmentation ELISA, were determined. SOluble TNF-alpha and LTB4 were measured from supernatants from bronchoalveolar lavage samples, using ELISA. RESULTS: Treatment with tilmicosin resulted in significant (P < 0.05) clearance of P haemolytica and neutrophil apoptosis at 3 hours, and decreased concentration of LTB4 at 24 hours. Rectal temperatures, neutrophil infiltration, phagocytosis, oxidative functions, membrane leakage, and soluble TNF-alpha concentrations were not significantly affected by tilmicosin. CONCLUSION: Tilmicosin effectively controlled P haemolytica infection, induced neutrophil apoptosis, reduced pulmonary inflammation, and did not affect neutrophil infiltration or function. CLINICAL RELEVANCE: By inducing neutrophil apoptosis, tilmicosin prevents further amplification of inflammatory injury in P haemolytica-infected lungs.

Animals↗
PubMed1996

A cohort study on childhood asthma admissions and readmissions.

BACKGROUND: Admissions to hospitals for childhood asthma seem to be increasing, even though admissions for other childhood conditions are decreasing. We studied admissions and readmissions for childhood asthma in Ontario in an attempt to uncover factors relating to the admission patterns. METHODS: Using the hospital discharge data from the Canadian Institute for Health Information, 28,646 children with diagnoses of asthma were identified from April 1, 1989, to March 31, 1992. RESULTS: The admission rates for asthma among children in Ontario showed a 14.8% decrease from 1987 to 1992. This decline was observed primarily in 5- to 17-year-olds. Younger children had a fourfold risk of hospital admission for asthma. In the 4 years studied, 10,427 children (36.4%) were readmitted at least once, representing 22,114 readmissions, 16,196 (73.2%) of which were for asthma. The 6-month probabilities of readmission for asthma were 20.0% (0- to 4-year-olds) and 11.7% (5- to 17-year-olds). The estimated relative risks (RRs) indicated that younger children had a significantly higher risk of readmission for asthma (RR, 1.38; 95% confidence interval, 1.30 to 1.46) or asthma-related causes (RR, 5.02; 95% confidence interval, 4.16 to 6.05). CONCLUSIONS: The observed increasing trend in admissions for asthma among children in the 1970s and 1980s leveled off in the early 1990s. The declining admission rates were largely caused by the lower admission rates among school-aged children from 5 to 17 years. The relatively high admission and readmission rates of preschool children are still a concern. Further research is necessary to examine factors that influence admissions for asthma among young children.

Adolescent↗
PubMed1995

Influence of different flow modi during extracorporeal circulation on endothelial-derived vasoactive substances.

Influences of shear stress on endothelin (ET) as well as prostacyclin (PGF) levels are common findings in different experimental settings. Thus, plasma levels of both substances seem to be a good tool to verify if different flow modi can be produced in blood vessels by generating pulsatile flow with a roller pump. In the present study, 20 patients scheduled for elective aortocoronary bypass operation were divided into two groups at random. One group was perfused with nonpulsatile (CON-group) and the other with pulsatile flow (PULS-group) during extracorporeal circulation. ET and PGF plasma levels were monitored perioperatively together with parameters of renal function and haemodynamic data. ET values were only slightly elevated at the end of extracorporeal circulation (mean baseline value; CON 3.1 pg/ml and PULS 3.2 pg/ml; mean maximal values at the end of cardiopulmonary bypass (CPB) 4.0 pg/ml and 3.9 pg/ml respectively). Prostacylin values (median baseline values: CON 56.7 pg/ml and PULS 57.1 pg/ml) peaked at the end of operation (median CON 117.8 pg/ml and PULS 137.5 pg/ml respectively) with a subsequent small decrease. No differences between the groups could be observed at any time point with respect to vasoactive substances, urine output (CON 6.5 ml/min and PULS 6.2 ml/min) or haemodynamics during CPB. This confirms studies emphasizing that no effective microvascular pulsatile flow is generated by conventional pulsatile flow-generating devices. In the present study, normothermia and a constant flow rate were maintained during CPB. Aortic cannulae (body-surface-related not maximal large diameters) were inserted. Altering these procedures may have led to more pronounced differences between the groups. All patients had an uneventful course after the operation. Similar to other reports, the present study was not able to demonstrate any benefit of pulsatile perfusion during extracorporeal circulation.

Aged↗
PubMed1994

Comparison of the efficacy and tolerability of moclobemide and maprotiline in depressed patients treated by general practitioners.

We report the results of a multicenter, double-blind study conducted in a general practice setting, in which the efficacy and tolerability of moclobemide, a new antidepressant drug of the reversible inhibitor of monoamine oxidase type A class, were compared with those of maprotiline, a noradrenaline reuptake inhibitor often prescribed in the general practice setting. Participating general practitioners were required to make differential diagnoses of depressive disorders according to DSM-III criteria and then quantitatively assess the efficacy of treatment using the Hamilton Depression Rating Scale (HDRS) and the Zung self-rating depression scale (Zung SDS). One hundred thirty outpatients (mean age 48 years) with major depression according to DSM-III were randomized to receive either moclobemide 300 mg or maprotiline 75 mg daily for 4 weeks. From day 8, dosages were increased if necessary up to a maximum of 400 mg of moclobemide or 100 mg of maprotiline. The results showed that moclobemide was as effective as maprotiline (HDRS, Zung SDS); moclobemide appeared to have the same antidepressant and anxiolytic activity, but a stronger drive-enhancing effect. Moclobemide was the better-tolerated drug, producing fewer side effects than maprotiline did: in particular, fewer instances of somnolence and dry mouth. The good tolerability of the compound was confirmed by the qualitative assessments of the study physicians.

Antidepressive Agents↗
PubMed1993

Effect of ractopamine and sex on growth, carcass characteristics, processing yield, and meat quality characteristics of crossbred swine.

One hundred twenty-eight 64-kg crossbred barrows and gilts were administered either 0 or 20 ppm of Ractopamine (RAC) in a pelleted corn-soybean meal diet that contained either 17.5 or 19.6% CP. Carcass quality was evaluated after slaughter at 100 kg. Dietary protein levels produced few significant effects; therefore, data were pooled for analysis. Pigs fed RAC exhibited improvement in feed efficiency (P < .01), ADG (P < .01), and number of days to slaughter (P < .01). Pigs fed RAC had 1.8 mm less fat (P < .05) and 3.4 mm more lean (P < .01) at the grading probe site. Gilts had 4.9 mm less fat than barrows at the probe site (P < .01) and also yielded an estimated 4.1% more lean (P < .01). Trimmed loins and bellies of animals fed 20 ppm of RAC were 230 g heavier (P < .05) than those of animals fed the control diet. Trimmed loins from gilts were 260 g heavier (P < .05), whereas barrows produced bellies that were 490 g heavier (P < .05) than those of gilts. The yield of processed ham was greater from both pigs fed RAC (P < .01) and barrows (P < .05). Loins of pigs fed RAC had lower cooking loss (P < .05), greater Warner-Bratzler shear value (P < .05), and higher fragmentation index value (P < .01). Although effects of sex were similar to or greater than the effects of 20 ppm of RAC, these effects were additive.

Adrenergic beta-Agonists↗
PubMed1990

[Modification of degenerative and regenerative processes in peripheral nerves by treatment with B vitamins].

Degenerative and regenerative changes in the saphenous nerve of the rabbit following systemic treatment with either a combination of the vitamins B1, B6 and B12 or physiological saline solution were investigated. Cold lesion of the nerve (-196 degrees C), which led to an optimal axonotmesis, was used to cause a secondary degeneration. The nerves were removed and investigated by light and electron microscopy after 4, 10 and 21 days. Morphological results show that the number of regenerating axons is higher and that of degenerating axons lower in the group treated with the given doses of vitamins than in the comparable control group. An explanation of the underlying metabolic processes is as yet not possible. Further investigations considering the contribution of the individual vitamins to the enhancement of degenerative and regenerative processes are necessary. Clinical indications of neurotoxicity due to the dose levels used here were not observed.

Animals↗
PubMed1990

Inositol monophosphate esterase inhibition by lithium in normal human studies using neuroendocrine tests. Part I. PRL and TSH responses to TRH.

1. Many neuroendocrine events are mediated by intracellularly second messengers, among which are the breakdown of phosphatidylinositol 4,5-biphosphate (PIP2). 2. Lithium (Li) was shown in therapeutic doses to be a specific inhibitor of the enzyme inositol monophosphate esterase Li reduces the turnover of PIP2 and diminishes the cell responses. 3. In order to investigate this new mode of action of Li the authors studied the influence of acute dose of Li on the response of prolactin (PRL) and thyrotropin (TSH) to thyrotropin stimulating hormone (TRH), a stimulation mainly mediated through the activation of the turnover of PIP2. 4. In seven normal subjects a single dose of 19.80 meq of Li reduced the response of PRL in 4, and augmented it in 3 subjects: Li decreased the TSH response in 4 subjects, it was increased in 1 and remained unchanged in 2. 5. These results are discussed in the light of the different interactions between hormone secretion, and the fact that adenopituitary is located out of the brain blood barrier.

Adult↗
PubMed1990

Inositol monophosphate esterase inhibition by lithium in normal human studies using neuroendocrine tests. Part II. HGH, PRL and TSH responses to clonidine.

1. Recent preclinical researches gave evidence that the actions of many neurotransmitters and drugs are mediated through the activation of the turnover of phosphatidylinositol 4,5 biphosphate (PIP2). Lithium (Li) a specific inhibitor of the enzyme inositol monophosphate esterase reduces the turn over of PIP2 and decreases the cell responses mediated via the cleavage of PIP2. 2. The authors studied the influence of a therapeutic single dose of Li on the response of human growth hormone (HGH) prolactin (PRL) and thyrotropin (TSH) to clonidine (C), an alpha adrenergic agonist which stimulates the turn over of PIP2. 3. Li reduces the HGH response to C in 3, increases in 1 and provokes no change in 2 subjects. The basal secretion of PRL and TSH were not modified. 4. These findings could support the hypothesis that some of the action of Li in humans is mediated through the inhibition of the enzyme inositol monophosphate esterase. Further studies are needed in order to determine the importance of this action.

Adult↗
PubMed1990

A contribution to the scientific assessment of degenerative and regenerative processes of peripheral nerve fibers following axonotmesis under the systemic administration of vitamins B1, B6 and B12--light and electron microscopy findings of the saphenous nerve in the rabbit.

The present study investigates the de- and regenerative changes in the saphenous nerve of the rabbit following systemic treatment with a combination of the vitamins B1, B6 and B12 and a control group that was treated with physiological saline solution. Cold lesion of the nerve, which led to an optimal axonotmesis, was used to cause a secondary degeneration. After 4, 10 and 21 days the nerves were removed and investigated by light and electron microscopy. The morphological results show that the number of regenerating axons is higher and that of degenerating axons lower in the group treated with the given doses of the vitamins than in the comparable control group. Statements as to the metabolic processes and vitamins from which the better regeneration results are due are as yet not possible. Further investigations with the individual vitamins are necessary. Clinical indications of neurotoxicity due to the dose levels used were not observed in any of the cases.

Animals↗