The renal adenosine system: structure, function, and regulation.
Explore the source record for details and available documents.
Adenosine↗
Biomedical subjects
B A Olson
Publications and source records attributed to B A Olson.
Characterization of adenosine A1 receptor in a cell line (28A) derived from rabbit collecting tubule.
We have previously reported that in several renal cell types, adenosine receptor agonists inhibit adenylyl cyclase and activate phospholipase C via a pertussis toxin-sensitive G protein. In the present study, in 28A cells, both of these adenosine receptor-mediated responses were inhibited by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a highly selective A1 adenosine receptor antagonist. The binding characteristics of the adenosine A1 receptor in the 28A renal cell line were studied using the radiolabeled antagonist [3H]DPCPX to determine whether two separate binding sites could account for these responses. Saturation binding of [3H]DPCPX to 28A cell membranes revealed a single class of A1 binding sites with an apparent Kd value of 1.4 nM and maximal binding capacity of 64 fmol/mg protein. Competition experiments with a variety of adenosine agonists gave biphasic displacement curves with a pharmacological profile characteristic of A1 receptors. Comparison of [3H]DPCPX competition binding data from 28A cell membranes with rabbit brain membranes, a tissue with well-characterized A1 receptors, reveals that the A1 receptor population in 28A cells has similar agonist binding affinities to the receptor population in brain but has a considerably lower density. Addition of guanosine 5'-triphosphate (100 microM) to 28A cell membranes caused the competition curves to shift from biphasic to monophasic, indicating that the A1 receptors exist in two interconvertible affinity states because of their coupling to G proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
Adenosine↗
Acute effects of ELF electromagnetic fields: a field study of linesmen working with 400 kV power lines.
The aim of the study was to investigate the possible acute effects of exposure to electric and magnetic fields. Twenty six experienced linesmen, aged 25 to 52, were studied during two working days while performing a simulated routine inspection of insulators on steel poles of a 400 kV power line. During one of the working days the inspection was performed on a power line in operation and on the other day the same procedure was performed on an identical power line, which was not in operation. The two days were found to be comparable with regard to the physical workload which, on the basis of heart rate measurements, was estimated to be high. Exposure to the electric and magnetic fields was measured using a device designed for on-worker sampling on each linesman. The mean exposure for the working day was estimated to be 2.8 kV/m (SD = 0.35) and 23.3 microT (SD = 4.2). The possible effects of exposure were studied using a battery of four automated performance tests, EEG, a mood scale, and a questionnaire to assess subjective symptoms. All workers were examined immediately before and after each workday. Furthermore, blood samples were collected for each subject on three different occasions during each workday. The battery of behavioural tests comprised a test of simple reaction time, a vigilance test, a test of short term memory (digit span), and a perceptual test (symbol digit). The four EEG recordings for each worker were judged blindly and sorted with regard to amount and stability of alpha activity. The blood samples were used for an analysis of possible changes during the workday with regard to the following hormones: thyroid stimulated hormone, luteinising hormone, follicle stimulating hormone, prolactin, cortisol, testosterone, and neopterin. Detailed analyses of the results using both parametric and nonparametric tests showed no statistically significant difference between the two conditions which could be attributed to exposure to electric and magnetic fields.
Adult↗
Effect of route of administration on the development of organophosphate-induced delayed neurotoxicity in 4-week-old chicks.
The poor absorption of organophosphate delayed neurotoxins through the gastrointestinal tract has been suggested as a reason why young chickens are not susceptible to organophosphate-induced delayed neurotoxicity (OPIDN). In the present study, 4-wk-old White Leghorn chickens were administered a single dose of 500 mg tri-o-tolyl phosphate (TOTP)/kg body weight or 100 mg o-tolyl saligenin phosphate (TSP)/kg body weight via the oral, intramuscular, or intraperitoneal route. In addition, TOTP TSP were administered intravenously at 250 and 50 mg/kg body weight, respectively. Forty-eight hours after dosing, half the birds in each group were killed for subsequent determination of whole-brain and sciatic nerve neurotoxic esterase (NTE) activity while the remaining 5 birds per group were observed daily from d 7 through d 21 for development of OPIDN clinical signs. TOTP administered by the 4 routes generally resulted in whole-brain and sciatic nerve NTE inhibition in excess of 85%. TSP given via the different routes resulted in 75-84% inhibition of whole-brain NTE activity and 66-79% inhibition of sciatic nerve NTE activity. No birds displayed clinical signs typical of OPIDN during the 21-d test. Thus, the resistance of the young chicken to the delayed effects of organophosphate compounds is due to factors other than the poor absorption of the compound through the gastrointestinal tract or the inability of the bird to convert TOTP to its neuroactive metabolite, TSP.
Administration, Oral↗
Fragment length polymorphisms among independent isolates of Epstein-Barr virus from immunocompromised and normal hosts.
DNA restriction fragment length polymorphisms of Epstein-Barr virus (EBV) DNA were used as a molecular epidemiological tool to study multiple isolates of virus from the same and different individuals. We studied 35 EBV isolates: 19 from seven immunocompromised children and 16 from seven college students with mononucleosis. Analysis of the fragment length polymorphisms in this collection of isolates permitted several conclusions. Sites of polymorphism were most often encountered in regions with repetitive DNA. Epidemiologically unrelated patients harbored viruses that could be readily distinguished; by contrast, two infants and their mothers harbored similar viruses. Isolates from different sites in the same patient were similar. Variations between different clinical isolates of EBV mimic those found between different laboratory strains of the virus. Fragment length polymorphisms thus provide a useful marker for studying transmission and pathogenesis of EBV infections.
Adolescent↗
Toxicity of 3,4,5,3',4',5'-hexachlorobiphenyl to mink.
Explore the source record for details and available documents.
Animal Feed↗
Chronic toxicity of dietary fluorine to mink.
Seventy-two 3-mo-old pastel mink were fed diets that contained 0, 33, 60, 108, 194 or 350 ppm supplemental fluorine (F), as NaF, for 382 d to assess its effects on growth, fur quality, reproduction and survivability. The basal diet contained 35 ppm F as fed. No significant differences were observed in body weight gains or fur quality between the controls and any of the F-treated groups (P greater than .05). Some males fed 350 ppm supplemental F for a 4-mo period prior to pelting had weakened frontal, parietal and femoral bones that fractured during the pelting process. The F treatments had no measurable adverse effects on breeding, gestation, whelping or lactation, although only 14% of the kits whelped by females fed 350 ppm F survived to 3 wk of age. The survivability of the adult mink was adversely affected only at 350 ppm supplemental F. At the termination of the study, no differences were observed in hematologic parameters or serum calcium concentrations between the controls and treated mink (P greater than .05), but serum alkaline phosphatase activities were increased (P less than .05) by the two highest dietary F levels. Serum F levels were elevated (P less than .01) only in mink fed 194 and 350 ppm F, and urinary and femoral F concentrations in the treated animals were generally greater (P less than .05; P less than .01) than control values and were closely related with dietary F levels. Femoral ash contents of the 194 and 350 ppm F-treated mink were less than the control values (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Toxicological manifestations of 2,4,5,2',4',5'-, 2,3,6,2',3',6'-, and 3,4,5,3',4',5'-hexachlorobiphenyl and Aroclor 1254 in mink.
Adult female mink were fed diets that contained 2.5 ppm Aroclor 1254, 0.1 or 0.5 ppm 3,4,5,3',4',5'-hexachlorobiphenyl (345 HCB), 2.5 or 5.0 ppm 2,4,5,2',4',5'-hexachlorobiphenyl (245 HCB) or 2,3,6,2',3',6'-hexachlorobiphenyl (236 HCB), or a control diet from 1 mo prior to breeding through parturition. All mink fed 0.5 ppm 345 HCB died within 60 d, while those fed 0.1 ppm showed 50% mortality after 3 mo exposure. Only one stillborn kit was whelped in the Aroclor 1254 group. No adverse reproductive effects were observed in the animals fed 236 HCB or 245 HCB. Plasma progesterone concentrations were significantly depressed by Aroclor 1254 and significantly elevated by 0.1 ppm 345 HCB. 17 beta-Estradiol concentrations were not significantly altered by any of the dietary treatments. Hepatic microsomal cytochrome P-450 concentrations were significantly elevated by all treatments except 236 HCB, with the largest increases occurring in mink exposed to Aroclor 1254 and 345 HCB. Aminopyrine N-demethylase activity was elevated by 5.0 ppm 245 HCB. Aroclor 1254 caused significant elevations in both benzo[a]pyrene hydroxylase and ethoxyresorufin O-deethylase activities. Benzo[a]pyrene hydroxylase activities were also significantly elevated in mink fed 245 HCB and 345 HCB. Aroclor 1254 caused a significant elevation in cerebellar and hypothalamic norepinephrine concentrations and a significant elevation in hypothalamic dopamine concentrations. Cerebral dopamine was elevated by 0.1 ppm 345 HCB, while midbrain dopamine levels were depressed. Norepinephrine concentrations were significantly elevated by 5.0 ppm 236 HCB in the midbrain and by 5.0 ppm 245 HCB in the medulla.
Administration, Oral↗
Coexposure to toluene and p-xylene in man: central nervous functions.
Sixteen men were studied in an exposure chamber to assess the effect of four hours' exposure to toluene (3.25 mmol/m3), xylene (2.84 mmol/m3), a mixture of toluene and xylene (2.20 + 0.94 mmol/m3), and a control condition. With the aid of microcomputers, subjects performed tests of simple reaction time, short term memory, and choice reaction time immediately after entering the chamber, after two, and after four hours' exposure. The results indicate that the performance on the tests was unaffected by exposure. In the light of this result the risk of an acute effect on central nervous functions after exposure for four hours at concentrations that do not exceed the Swedish threshold limit values was considered to be minimal.
Adult↗
Polychlorinated biphenyls (Aroclors 1016 and 1242): effect on hepatic microsomal mixed function oxidases in mink and ferrets.
Explore the source record for details and available documents.
Animals↗
Reaction time changes among steel workers exposed to solvent vapors. A longitudinal study.
A longitudinal study was performed to investigate the behavioral changes associated with occupational exposure to organic solvents. An initial simple reaction time (SRT) test was performed on a group of steel workers who were exposed to vapor concentrations of solvents clearly exceeding threshold limit values (TLVs). A second SRT measurement was made six months following the completion of major improvements in the hygiene quality of the work environment which resulted in a reduction of exposure levels to 20% of the TLVs valid at the time. Approximately fifteen months after this measurement, a final SRT test was performed. The workers' performance on the SRT test improved over the three measurements. At the first measurement occasion SRT was found to be related to the degree of exposure, while no such relation could be observed on the following measurement occasions. The results indicate that the workers' central nervous functioning had been negatively affected by solvent exposure and that this effect was at least partially reversible in nature; they thus confirm the importance of changes which enhance the hygienic quality of the work environment.
Adolescent↗
Long-term exposure to jet fuel. II. A cross-sectional epidemiologic investigation on occupationally exposed industrial workers with special reference to the nervous system.
Thirty jet fuel exposed workers selected according to exposure criteria and thirty nonexposed controls from a jet motor factory were examined, with special reference to the nervous system, by occupational hygiene physicians, psychiatrists, psychologists, and neurophysiologists. The controls and the exposed subjects were matched with respect to age, employment duration, and education. Among the exposed subjects the mean exposure duration was 17 years, and 300 mg/m3 was calculated as a rough time-weighted average exposure level. The investigation revealed significant differences between the exposed and nonexposed groups for (a) incidence and prevalence of psychiatric symptoms, (b) psychological tests with the load on attention and sensorimotor speed and (c) electroencephalograms. When the control group was selected, it was ensured that the two groups were essentially equivalent except for exposure to jet fuel. It is concluded, therefore, that the differences found between the groups are probably related to exposure to jet fuel.
Adult↗
Exposure to trichloroethylene III. Psychological functions.
The effect of exposure to the solvent trichloroethylene (TRI) on the performance of tests of numerical ability, reaction time (simple and choice), and short-term memory was studied in 15 healthy male subjects. The subjects were tested individually on three different occasions during exposure to 540 and 1,080 mg/m3 of TRI in inspiratory air and under control conditions, respectively. At predetermined times during the three 70-min exposure periods, samples were taken of the subjects' alveolar air. Neither the reaction time tests nor the short-term memory test showed any signs of performance decrement during exposure to TRI as compared to those administered under control conditions. However, a statistically significant decrement in performance was obtained on the test of numerical ability during exposure to TRI. The results as a whole indicate that there should not be any risk of an acute effect on central nervous functions at concentrations which do not considerably exceed the Swedish threshold limit value for the solvent (160 mg/m3).
Adult↗
Microsomal enzyme induction, egg production, and reproduction in three lines of Japanese quail fed polybrominated biphenyls.
The sensitivity of three genetic lines of Japanese quail to polybrominated biphenyls (PBBs) was evaluated using criteria of egg production, reproduction, and induction of the hepatic microsomal mixed-function oxidase (MFO) system. Two genetic lines of quail, developed to diverge in their plasma cholesterol response to exogenous adrenocorticotropin (ACTH) (a "Low" line and a "High" line), were compared to a random-bred line ("Random"). ACTH administration caused increases in plasma cholesterol in the Low line that were 15 and 39% below the Random-line values in males and females, respectively, while High-line values were 31% higher in males and 36% higher in females when compared to the respective Random-line values. Hepatic activities of aryl hydrocarbon hydroxylase (AHH) and hexobarbital hydroxylase (HxH) were not significantly influenced by ACTH administration or by genetic line in either sex. PBBs fed at 40 or 80 mg/kg diet for 5 wk resulted in significant increases in hepatic AHH and aminopyrine N-demethylase (APND) activities and cytochrome P-450 concentrations. The induction of AHH, APND, and cytochrome P-450 was significantly less in Low-line males in comparison to Random- and High-line males, while the induction of AHH was less in Low-line females when compared to females from the other two lines, based on covariance analysis. In terms of reproductive parameters, there was a greater adverse effect on egg production at 80 ppm PBBs in Low-line females when compared to the Random and High lines. These data indicate an example in which the biological toxicity of a compound and the induction of a 3-methylcholanthrene-type hepatic enzyme are not directly correlated.
Adrenocorticotropic Hormone↗
Biological and induction effects of phenobarbital and 3-methylcholanthrene in mink (Mustela vison).
Mink were injected (ip) daily with 20 mg/kg of 3-methylcholanthrene (MC) or 40 mg/kg of phenobarbital (PB) for 3 days and killed 48 hr after the last injection. The duration of anesthetic action of PB increased after each injection. MC-treated mink became anorexic and lost substantial body weight. PB caused enlargement of liver and lungs, whereas MC caused liver atrophy. No major treatment-related morphologic changes including amount of endoplasmic reticulum (ER) in liver were revealed by electron microscopic examination. Microsomal protein content was not increased and NADPH cytochrome P-450 reductase was not induced in liver by either PB or MC. Cytochrome P-450 (448) was increased 3.2-fold by PB and 2.5-fold by MC. Cytochrome b5 was increased 2.3-fold by MC but was not affected by PB. Aminopyrine N-demethylase was enhanced 5.1-fold in activity by PB whereas hexobarbital hydroxylase was not induced. MC-treatment moderately increased the activities of benzo(a)pyrene hydroxylase (1.7-fold) and ethoxyresorufin O-deethylase (2.1-fold) but had no effect on ethoxycoumarin O-deethylase. The most distinctive features of the mink revealed by this study are a) lack of PB induction of the ER, microsomal protein content, NADPH-cytochrome P-450 reductase, and hexobarbital hydroxylase, and b) lack of MC induction of cytochrome P-448-associated mixed function oxidases that are known to be highly responsive to MC in other species.
Animals↗