摘要:

AbstractRates of enzymatic single‐electron reduction of some myotoxc quinones to semiquinone metabolites in anin vitroxanthine oxidase/hypoxanthine/catalase system varied widely. Naphthoquinones, especially juglone, were found to undergo rapid single‐electron reduction. Benzoquinones and benzoquinoneimines, as well as phenanthrene‐9,10‐quinone, benzo[a]pyrene‐3,6‐quinone, and diethylstilbestrolquinone, were also actively reduced. The anthraquinones danthron, doxorubicin and emodin were poorly metabolized in this system.N‐Acetylcysteine inhibited quinone‐stimulated cytochrome C reduction at high concentrations. The results of this study are discussed with respect to cytotoxicity and mutagenicity of se

ISSN:0260-437X    

DOI:10.1002/jat.2550090502

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA mercury vapour generating system is described that is based on the reduction of HgCI2by SnCI2in the input airstream of the inhalation chamber. The solutions of the two chemicals are pumped by peristaltic pumps from reservoirs through a miniature mixing chamber into the upper part of a sloping glass tube (reduction chamber) through which air is sucked into the inhalation assembly. The liquid flows down the slope and through a port into a Quickfit flask. Reservoirs can be filled and the collecting flask emptied without interruption of exposure. The desired vapour concentration is achieved by varying the rate of mercury injection and the rate of airflow. Concentration in the inhalation chamber can be measured by passing air through a mercury vapour monitor or by radioactivity when203HgCI2is used and a known volume of air is passed through a hopcalite absorber. Operation instructions and an experimental example with mice are given.

ISSN:0260-437X    

DOI:10.1002/jat.2550090503

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe expiratory bradypnoea indicative of upper airway irritation in mice was evaluated duringa15‐min oronasal exposure to increasing concentrations of twenty aliphatic amines. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each test compound. Moreover, eight out of the twenty amines were tested for pulmonary toxicity in mice and for the effects of a 120‐min exposure on the respiratory rates of non‐anaesthetized, traheally cannulated mice (RD50TC). Both allylamine and diallylamine showedRD50values of 9 ppm and 4 ppm, respectively, while theRD50values associated with exposure to saturated amines ranged from 50 to 200 ppm. Among the eight amines tested for both upper airway irritation and pulmonary toxicity, diisopropylamine and di‐n‐butylamine showed aRD50TC/RD50ratio of<1, indicating that the respiratory toxicity induced by these two amines would be related primarily to pulmonary effects. On the basis of prior predictions proposed for upper airway irritants, tentative standards are given for ten amines. Moreover, it is suggested that the basis of standards for industrial exposure to diisopropylamine and di‐n‐butylamine should

ISSN:0260-437X    

DOI:10.1002/jat.2550090504

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of intratracheally instilled slate dust on the phospholipid profile, and14C‐acetate incorporation into the lipids of lung lavage, whole lung tissue and its subcellular fractions, has been studied in rats. The acellular fraction of lung lavage showed a decrease in the phospholipid content at 4 days and then an increase at 40 days of dust exposure, whereas the cellular fraction showed the reverse. The order of14C‐acetate incorporation into total lipids and individual phospholipids showed a parallel trend. The rate of incorporation with total lipids of lung tissue was higher at the two stages of dust exposure and a similar pattern prevailed in the subceiiuiar fractions, i.e. mitochondrial, microsomal and cytosolic fraction. Acetate incorporation was highest in mitochondria, followed by the microsomes. An increase in the microsomal and mitochondrial cholesterol levels was also observed. There was no significant change in the solvent‐extracted14C‐counts of whole plasma, trichloroacetic acid (TCA) precipitate and TCA supernatant of plasma. The results indicate that slate dust causes an enhanced synthesis of pulmonary surfactant and other lung lipids and, therefore, has an effect on the metabolism of type II alveolar epithelia

ISSN:0260-437X    

DOI:10.1002/jat.2550090505

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractStudies were conducted to investigate the effect of vanadium (V5+), cadmium (Cd2+), mercury (Hg2+), aluminium (Al3+), lead (Pb2+) and manganese (Mn2+) ions on calmodulin (CaM)‐related Ca2+‐ATPase activity in rhesus monkey (Macaca mulatta) brain (RMB). The cerebral cortex of RMB was dissected and homogenized in 10% sucrose buffer, and synaptic plasma membranes (SPM) were prepared. Ca2+‐ATPase activity was determined by the inorganic phosphate method. Different concentrations of metal ions were incubated with RMB fractions containing endogenous CaM and RMB fractions without CaM. The results show that no metal ion inhibited the basal enzyme but that they showed a profound inhibition of total Ca2+‐ATPase containing CaM. The order of potency of metals was Hg>Cd>Pb>Mn>Al>V. Exogenous addition of CaM restored the metal‐inhibited enzyme activity to near the normal level. The basal enzyme, when reconstituted with CaM, showed sensitivity to metal ions. These data, presented for the first time in non‐human primate brain, indicate that the metal ions inhibit CaM acti

ISSN:0260-437X    

DOI:10.1002/jat.2550090506

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractVolume, specific gravity, creatinine, lactate dehydrogenase (LDH), leucine aminopeptidase (LAP), betagalactosidase (GAL), leucocytes, erythrocytes, nitrite, protein (albumin), glucose, ketone, urobilinogen, bilirubin and pH were estimated in urine of rats after single (by gavage) or repeated (via drinking water) oral administration of diethyiene glycol (DEG). Following single or repetitive doses (daily over 90 days) of 0.2 g DEG kg−1body weight, no change in renal function was observed (no effect level). In urine of rats treated once with 0.7 g DEG kg−1body weight, LDH activity was significantly enhanced one day after treatment. A single dose of 2.0 g DEG kg−1body weight resulted in an additional rise in urinary GAL activity two days after treatment, a significant rise of urinary volume and a decrease in creatinine concentration and pH on the first day. One day following a single dose of 8.0 g DEG kg−1body weight, in addition to the changes mentioned before, LAP activity was significantly elevated and the specific gravity decreased. However, in all experiments the wet weight of the kidneys remained normal as compared to controls. The results thus show dose‐dependent changes in several renal parameters, indicating a slight‐to‐moderate and reversible ren

ISSN:0260-437X    

DOI:10.1002/jat.2550090507

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractAn improved and simplified spectrophotometric method for the determination of carboxyhemoglobin (COHb) is described, which employs an equation to correct for the dissociation error during analysis. Two microliters, or less, of blood is diluted with an ammonium hydroxide solution directly in the measuring cuvette. A layer of light mineral oil overlying the diluent was found to increase measured COHb saturation of blood equilibrated with 100% CO. Sodium dithionite treatment of the oil further increased this value in one case. The measured COHb was shown to be affected directly by factors that alter hemoglobin concentration in the diluent (i.e. blood volume, hematocrit). Blood samples kept cold and under oil may be stored safely for as long as 10 days. Measurement of COHb by this method in rats exposed to 525, 900, 1800 and 2400 ppm CO produces higher values than those obtained with the 1965 spectrophotometric method of Commins and Lawther. Variations on the method of Commins and Lawther, as well as COHb values available in the literature for animals exposed to CO, are reviewed briefly.

ISSN:0260-437X    

DOI:10.1002/jat.2550090508

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractValues for the indepedent kinetic variables, clearance (CL) and volume of distribution (V), for six xenobioticsantipyrine, ethosuximide, phencyclidine, theophylline, valproic acid and warfarin—were culled from the literature for each of three small subhuman species and for humans, and then allometrically scaled. Scaling was performed in two ways. First, using kinetic data acquired for three small subhuman species and for man, scaled parameters were observed for goodness of fit to a standard allometrie expression. Second, scaled parameters were averaged for three subhuman species. Mean scaled kinetic parameters from only three species were used to predict half‐life values of the xenobiotics in humans. Finally, predicted percentages of the xenobiotic burdens remainig in humans at the end of four allometrically‐predicted half‐lives were compared with the expected percentages of remainig xenobiotic based upon four actual half‐lives in humans. The results suggest that it may be feasible to estimate, using three small subhuman specie, allometrically‐derived toxicokinetic parameters of some substances in man with sufficient accuracy to be of prac

ISSN:0260-437X    

DOI:10.1002/jat.2550090509

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis study demonstrates the greater susceptibility of the heart as compared to the kidney to cadmium in the presence of high dietary selenium. Male weanling rats were fed an adequate‐copper low‐selenium feed supplemented with 0, 10 or 50 ppm copper with or without 50 ppm dietary cadmium for 7 weeks. All rats received 0.5 ppm selenium in their drinking water. Cadmium treatment resulted in histopathological lesions in the heart, but not in the kidney. Although cadmium treatment resulted in more extensive effects on glutathione peroxidase and superoxide dismutase in the heart as compared to the kidney, no increase in peroxidation was noted in either organ, suggesting that cadmium cardiotoxicity can be dissociated from tissue peroxidation. Mean cadmium concentrations in the heart ranged from 0.55 to 1.22 μg cadmium g−1tissue, wet weight, and in the kidney from 11.53 to 21.04 μg cadmium g−1tissue, wet weight, and in the kidney from 11.53 to 21.04 μg cadmium g−1tissue, wet weight. In both tissues examined, cadmium levels were influenced by dietary copper and heart cadmium concentrations did not correlate with either the biochemical or histological lesions observed. Thus, tissue cadmium levels alone may not be adequate for predicting cadm

ISSN:0260-437X    

DOI:10.1002/jat.2550090510

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractEthanol (1, 2 or 5 g kg−1) and lead (0.55 g I−1in drinking water) were given either alone or in combination for 4 months to rats. The uptake of lead in tissues, some lead‐sensitive variables, the levels of biogenic amines in different brain regions, hepatic lipid peroxidation, glycogen and blood glucose concentrations were measured.Ethanol or lead when given alone inhibited the activity of blood δ‐aminolevulinic acid dehydratase (ALAD). The co‐administration of 5 g kg−1but not 1 or 2 g kg−1ethanol significantly enhanced the lead‐induced inhibition of blood δ‐ALAD activity and the elevation of δ‐aminolevulinic acid (ALA) excretion. Co‐exposure to lead and ethanol (5 g kg−1) produced a more pronounced increase in hepatic lipid peroxidation and blood glucose level than either ethanol or lead alone. This combination also caused a significant increase in the dopamine (DA) contents of striatum, midbrain and pons medulla, norepinephrine (NE) contents in midbrain and 5‐hydroxytryptamine (5‐HT) contents of hypothalamus, striatum, midbrain and pons medulla over levels produced by lead alone. However, the level of NE in hypothalamus decreased upon co‐administration. The uptake and retention of lead was significantly higher in blood, liver, kidney and brain in animals co‐exposed to lead and 5 g kg−1ethanol. Blood and kidney lead was also increased by 2 g kg−1ethanol. The results suggest that prolonged and heavy consumption of alc

ISSN:0260-437X    

DOI:10.1002/jat.2550090511

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY