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Biomedical subjects

J Cook

Publications and source records attributed to J Cook.

315 records · Page 18Linked to original sources
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Multiresidue analysis of pesticides in fresh fruits and vegetables using procedures developed by the Florida Department of Agriculture and Consumer Services.

Improved quality and efficiency of pesticide residue analysis were achieved by examining all aspects of the laboratory process. In an effort to eliminate methylene chloride hazardous waste, an acetonitrile extraction method, originally developed by the California Department of Agriculture, was modified and adopted. Sample size and solvent consumption were reduced with the new method. Custom glassware racks and disposable supplies reduced overall analysis time. Gravity-fed, solid-phase extraction simplified sample preparation and provided cleaner extracts for gas chromatographic analyses. Modifications to the method were made to achieve the ruggedness needed to maintain quality objectives during routine analysis. Instrumental improvements, including new selective detectors, retention time locking, and mass spectrometry screening for all samples, provided the laboratory with efficient, reliable, and confirmed analytical results.

Acetonitriles↗
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A short break.

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Adult↗
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Intensive standards.

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Clinical Protocols↗
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Role of beta 2-receptor stimulation in the peripheral vascular actions of the antihypertensive dilevalol.

Dilevalol (SCH 19927) is a potent, long-acting, nonselective beta-blocker with marked vasodilator actions. Unlike classical beta-blockers, dilevalol promptly lowers blood pressure and vascular resistance in animal models of hypertension. The present studies address the peripheral vascular effects of dilevalol and explore the role of beta-receptor agonism in the acute vasodilator and antihypertensive effects of the compound. In the denervated dog hindlimb preparation, dilevalol (0.1, 0.3, 1.0 and 3.0 micrograms, i.a.) significantly increased femoral blood flow by 12 +/- 6, 27 +/- 6, 84 +/- 31 and 132 +/- 41 ml/min, respectively. In contrast, celiprolol, a beta-blocker with purported vasodilator activity, caused a significant increase in flow of 31 +/- 9 ml/min at a dose of 30 micrograms i.a. Systematic pretreatment with the selective beta 2-antagonist ICI 118,551 virtually abolished dilevalol's vasodilator effect in the dog hindlimb. In conscious spontaneously hypertensive rats, 3 mg/kg i.v. dilevalol reduced blood pressure by 58 +/- 8 mmHg (P less than 0.05) and vascular resistance by 171 +/- 27 dyne.sec.cm-5/100 g (P less than 0.05) but did not change cardiac output significantly. Pretreatment of spontaneously hypertensive rats with ICI 118,551 significantly reduced both dilevalol's antihypertensive and resistance-lowering effects. Oral doses of 10 and 25 mg/kg dilevalol lowered blood pressure by 19 +/- 3 (P less than 0.05) and 37 +/- 5 mmHg (P less than 0.05) in spontaneously hypertensive rats with chronically implanted Doppler flow probes. The lower dilevalol dose reduced mesenteric vascular resistance 38 +/- 6% (P less than 0.05) while the higher dose significantly lowered vascular resistance in the hindlimb, mesenteric and renal vascular beds of spontaneously hypertensive rats by 18 +/- 8, 33 +/- 2 and 43 +/- 4%, respectively. Propranolol lowered neither blood pressure nor regional vascular resistances at the above doses in spontaneously hypertensive rats. Thus, dilevalol promotes a generalized fall in vascular resistance. Furthermore, the present studies illustrate that beta 2-receptor stimulation plays an obligatory role in both the vasodilatory and antihypertensive actions of dilevalol.

Adrenergic beta-Agonists↗
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Altered pharmacokinetics of recombinant human deoxyribonuclease in rats due to the presence of a binding protein.

Preclinical pharmacokinetic studies with recombinant human DNase (rhDNase) following a single intravenous injection of 0.01, 0.1, or 1.0 mg/kg in male rats demonstrated that clearance and steady-state volume of distribution increased at the 1.0 mg/kg dose, whereas the mean exit time from the serum remained unchanged. To characterize the molecular form of 125I-rhDNase in serum, rats were intravenously injected with approximately 300 microCi (5 micrograms)/kg 125I-rhDNase or approximately 300 microCi (5 micrograms)/kg 125I-rhDNase with 1 mg/kg unlabeled rhDNase, and blood samples were taken at 2 min. Urine was collected from one rat in each group from 0-6 and 6-24 hr after injection. Serum samples were analyzed by trichloroacetic acid precipitation and native PAGE; urine samples were analyzed by size exclusion HPLC. Native PAGE results indicate that there is a protein present in the serum that binds rhDNase specifically. The presence of excess unlabeled rhDNase decreases the 125I-rhDNase-binding protein complex level relative to free 125I-rhDNase. In contrast, a high-molecular weight peak of radioactivity was seen after size exclusion HPLC of the urine from the animal that received 125I-rhDNase with unlabeled rhDNase rather than the animal that received 125I-rhDNase alone. In addition to its effects on disposition, a specific serum binding protein for rhDNase may play a role in modulating the bioactivity of circulating rhDNase.

Animals↗
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Obesity in children and adolescents.

The prevalence of obesity in children and adolescents is increasing. For those whose weight is greater than or equal to 120% IBW a thorough evaluation is needed to determine the etiology. The majority of children will have exogenous obesity and will not require extensive diagnostic testing. Complications of obesity occur in children and adolescents with psychosocial being one of the more severe. Treatment is necessary to prevent complications and the only treatment that has been shown to be successful is a multidisciplinary family approach with long-term follow-up. The once a day pill to treat obesity is far in the future.

Adolescent↗