Search Results - (Author, Cooperation:T. R. Ward)

2012-11-01

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Alkenes/chemistry ; Benzamides/*chemistry ; Biotinylation ; Carbon/chemistry ; Catalysis ; Catalytic Domain ; Coordination Complexes/*chemistry ; Enzyme Activation ; Enzymes/*chemistry ; Hydrogen/chemistry ; Mutagenesis, Site-Directed ; *Protein Engineering ; Rhodium/*chemistry ; Streptavidin/*chemistry/genetics ; Substrate Specificity

1436-5073

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Zusammenfassung Eine kolorimetrische Methode zur Bestimmung von Pyrazol im Blut auf der Basis seines Reaktionsproduktes mit Pentacyanoaminoferrat(III) wurde ausgearbeitet. Sie eignet sich bis zur Größenordnung von 0,1μMol Pyrazol in 0,2 ml Probe. Im Serum normaler Tiere fanden sich keine die Bestimmung störenden Substanzen.

Summary A colorimetric procedure has been developed whereby pyrazole may be determined in blood. The pyrazole is assayed as a reaction product with pentacyanoaminoferrate(III). The method is rapid, straightforward, and will detect levels of pyrazole down to 0.1μmol in a total sample volume of 0.2 ml. There appears to be no interfering materials in the serum of normal animals.

Electronic Resource

1432-0738

Key words Polychlorinated biphenyls ; Calcium sequestration ; Cerebellum ; 45Ca2+-uptake ; In vitro ; Structure-activity relationships

Springer Online Journal Archives 1860-2000

Medicine

Abstract  Recent studies from our laboratory indicate that polychlorinated biphenyl (PCB) congeners in vitro perturbed signal transduction mechanisms including cellular Ca2+-homeostasis and protein kinase C translocation. We have now investigated the structure-activity relationship (SAR) of three PCB mixtures, 24 PCB congeners and one dibenzofuran for their effects on microsomal and mitochondrial Ca2+-sequestration in rat cerebellum. Ca2+-sequestration by these intracellular organelles was determined using radioactive 45CaCl2. All three mixtures studied, Aroclor 1016, Aroclor 1254 and Aroclor 1260, were equally potent in inhibiting microsomal and mitochondrial Ca2+-sequestration with IC50 values of 6–8 μM. 1,2,3,7,8-Pentachlorodibenzofuran had no effect on Ca2+-sequestration by these organelles. The SAR among the congeners revealed: (1) congeners with ortho-/meta- or ortho-, para-chlorine substitutions were the most potent in inhibiting microsomal and mitochondrial Ca2+-sequestration (IC50=2.4–22.3 μM); (2) congeners with only para- but without ortho-substitutions were not effective in inhibiting Ca2+-sequestration by microsomes and mitochondria; (3) increased chlorination was not related to the effectiveness of these congeners. The present SAR studies indicate that the effects of most PCB congeners in vitro may be related to an interaction at specific sites having preference for low lateral substitution or lateral content (meta- or para) in the presence of ortho-substitution.

Electronic Resource

0197-8462

microwave ; blood-brain barrier ; 1.7 GHz ; pulsed ; continuous wave ; rat ; low-power ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology

Wiley InterScience Backfile Collection 1832-2000

Biology

Physics

The permeability of the blood-brain barrier to high- and low-molecular-weight compounds has been measured as a function of continuous-wave (CW) and pulsed-microwave radiation. Adult rats, anesthetized with pentobarbital and injected intravenously with a mixture of [14C] sucrose and [3H] inulin, were exposed for 30 min at a specific absorption rate of 0.1 W/kg to 1.7-GHz CW and pulsed (0.5-μs pulse width, 1,000 pps) microwaves. After exposure, the brain was perfused and sectioned into nine regions, and the radioactivity in each region was counted. During identical exposure conditions, temperatures of rats were measured in eight of the brain regions by a thermistor probe that did not perturb the field. No change in uptake of either tracer was found in any of the eight regions as compared with those of sham-exposed animals.

2 Ill.

Electronic Resource

0197-8462

blood-brain barrier ; rats ; 2450-MHz microwaves ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology

Wiley InterScience Backfile Collection 1832-2000

Biology

Physics

Adult rats anesthesized with pentobarbital and injected intravenously with a mixture of [14C]sucrose and [3H]inulin were exposed for 30 min to an environment at an ambient temperature of 22, 30, or 40 °C, or were exposed at 22 °C to 2450-MHz CW microwave radiation at power densities of 0, 10, 20, or 30 mW/cm2. Following exposure, the brain was perfused and sectioned into eight regions, and the radioactivity in each region was counted. The data were analyzed by two methods. First, the data for each of the eight regions and for each of the two radioactive tracers were analyzed by regression analysis for a total of 16 analyses and Bonferroni's Inequality was applied to prevent false positive results from numerous analyses. By this conservative test, no statistically significant increase in permeation was found for either tracer in any brain region of rats exposed to microwaves. Second, a profile analysis was used to test for a general change in tracer uptake across all brain regions. Using this statistical method, a significant increase in permeation was found for sucrose but not for inulin. A correction factor was then derived from the warm-air experiments to correct for the increase in permeation of the brain associated with change in body temperature. This correction factor was applied to the data for the irradiated animals. After correcting the data for thermal effects of the microwave radiation, no significant increase in permeation was found.

1 Ill.

Electronic Resource

0197-8462

heat transfer ; electromagnetic dosimetry ; computer model ; squirrel monkey ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology

Wiley InterScience Backfile Collection 1832-2000

Biology

Physics

The rate of the electromagnetic energy deposition and the resultant thermoregulatory response of a block model of a squirrel monkey exposed to plane-wave fields at 350 MHz were calculated using a finite-difference procedure. Noninvasive temperature measurements in live squirrel monkeys under similar exposure conditions were obtained using Vitek probes. Calculations exhibit reasonable correlation with the measured data, especially for the rise in colonic temperature.

6 Ill.

Electronic Resource