The aminoacceptor stem of the yeast tRNA(Lys) contains determinants of mitochondrial import selectivity

The effect of quinine, a cinchona alkaloid, was studied on gastrointestinal transit in mice. Intraperitoneal (i.p.) administration of quinine inhibited the intestinal propulsion of a charcoal suspension at a dose of 100 mg/kg, comparing favorably with 5 mg/kg morphine. In an attempt to probe into the mechanism underlying this inhibition, a possible modulation by minoxidil (1 mg/kg, p.o.) and glibenclamide (1 mg/kg, p.o.), the drugs that, respectively, open and close ATP-sensitive K+ channels was tested on gastrointestinal transit in animals treated or not with quinine or morphine. While minoxidil produced no significant change of normal transit, glibenclamide significantly increased it. However, both drugs blocked the quinine-induced reduction in gastrointestinal transit. In contrast, the inhibitory effect of morphine on gastrointestinal transit was not modified by either drug. The effects of quinine as well as of morphine on gastrointestinal transit were significantly antagonized by naloxone (2 mg/kg, s.c.), a mu-opioid receptor antagonist but not by yohimbine (1 mg/kg, i.p.), an alpha2-adrenoceptor antagonist. Furthermore, quinine at a lower dose (25 mg/kg) that showed no per se effect on gastrointestinal transit, significantly potentiated the response to 2.5 mg/kg morphine. Although the role of ATP-sensitive K+ channels in the action of quinine and morphine was not clarified by the present results, a possible involvement of endogenous opioid(s) in the quinine-induced inhibition of gastrointestinal transit can be suggested.     

Effects of chromium (VI) addition on the activated sludge process

The effect of hexavalent chromium, Cr(VI), addition on various operating parameters of activated sludge process was evaluated. To accomplish this, two parallel lab-scale continuous-flow activated sludge plants were operated. One was used as a control plant, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5 mgl(-1). Cr(VI) concentrations of 0.5 mgl(-1) caused significant inhibition of the nitrification process (up to 74% decrease in ammonia removal efficiency). On the contrary, the effect of Cr(VI) on organic substrate removal was minor for concentrations up to 5 mgl(-1), indicating that heterotrophic microorganisms are less sensitive to Cr(VI) than nitrifiers. Activated sludge floc size and structure characterization showed that Cr(VI) concentrations higher than 1 mgl(-1) reduced the filaments abundance, causing the appearance of pin-point flocs and free-dispersed bacteria. Additionally, the variability of protozoa and rotifers was reduced. As a result of disperse growth, effluent quality deteriorated, since significant amounts of suspended solids escaped with the effluent. Termination of Cr(VI) addition led to a partial recovery of the nitrification process (up to 57% recovery). Similar recovery signs were not observed for activated sludge floc size and structure. Finally, shock loading to the control plant with 5 mgl(-1) Cr(VI) for 2 days resulted in a significant inhibition of the nitrification process and a reduction in filamentous microorganisms abundance.     

江苏德邦化工集团有限公司，江苏连云港 222023

1 简介 印度第一个纯碱厂始建于1932年，位于印度西部古吉拉特邦的Dhrangadhra，装置能力为50t/d。 作为基础无机化工产品，因为整个印度无天然碱矿，全部产品--包括轻灰和重灰只能以合成法生产。     

Quantification of historical dust exposures in the diatomaceous earth industry

Quantitative estimates of dust exposure in a diatomaceous earth (DE) mining and milling operation have been derived based on air sampling records for the period 1948-1988. A total of 6395 records was included in the analysis. Conversion of results obtained by particle counting, expressed as millions of particles per cubic feet (mppcf) of gravimetrically from a filter cassette and expressed as mg m-3 total, were converted to mg m-3 respirable dust using a conversion factor derived from data obtained during the same periods at the plant. Conversion factors were calculated as the average difference of means on the log scale in order to provide stable and consistent conversions and as a ratio of arithmetic means so that the results could be compared with similar studies. After converting the available data to mg m-3 respirable dust, geometric mean (geometric standard deviation) concentrations were 0.37 (2.43) during the 1950s and 0.17 (2.35) during later periods. Exposures were estimated using two linear models, one estimating the changes in concentration over time, and the other providing job-specific mean exposures during the more recent period. Extrapolation of the estimates to periods prior to the availability of any data was done using a subjectively-determined scaling factor. The average estimated respirable dust concentrations for 135 jobs were 3.55 (+/-1.25), 1.37 (+/-0.48), 0.47 (+/-0.16) and 0.29 (+/-0.10) mg m-3 prior to 1949, 1949-1953, 1954-1973 and 1974-1988, respectively. Despite the limitations of the available data, the estimation procedures used are expected to provide reasonable quantitative estimates of silica-containing dust exposure for subsequent exposure-response analyses.     

The ISO Headspace CO2 Biodegradation Test

Two published methods for evaluating the aerobic biodegradability of organic compounds by measuring inorganic carbon (CO2) production in sealed vessels, under a headspace of air were combined into one protocol. This was ring tested in 1995 by the International Organization for Standardization (ISO) using aniline and 1-octanol as the test substances. This paper describes the ISO method and discusses the results of the inter-laboratory calibration exercise in terms of the method's precision and performance.     

Clinical relevance of parvovirus B19 as a cause of anemia in patients with human immunodeficiency virus infection

Parvovirus B19 (B19) DNA was detected by dot blot hybridization in sera from 5 (17%) of 30 human immunodeficiency virus (HIV)-infected patients with hematocrits (HCT) of < or =24 and 4 (31%) of 13 HRV-infected patients with HCT of < or =20, suggesting that B19 is a reasonably common cause of severe anemia in HIV infection. The anemia promptly remitted after immunoglobulin therapy in 3 of 4 treated patients. The presence of IgM to B19, the clinical circumstance in which anemia developed, and the marrow morphology were poor predictors of chronic B19 infection. DNA hybridization studies of sera from 191 HIV-infected and 117 HIV-seronegative homosexual males attending a clinic in the Seattle area revealed that 1 (0.5%) and 2 (2%) samples, respectively, from the 2 groups contained B19. However, when assayed by polymerase chain reaction (PCR), 5% of the serum samples from HIV-infected persons and 9% from uninfected persons contained B19, although each had an HCT of > or =40. The data argue that anemia results from chronic high-titer B19 infection. Although a negative PCR assay excludes this diagnosis, DNA hybridization may be the more specific serum test.     

Cardiovascular effects of microinjections of opioid agonists into the ''Depressor Region'' of the ventrolateral periaqueductal gray region

Differentiating the binding properties of applied lectins should facilitate the selection of lectins for characterization of glycoreceptors on the cell surface. Based on the binding specificities studied by inhibition assays of lectin-glycan interactions, over twenty Gal and/or GalNAc specific lectins have been divided into eight groups according to their specificity for structural units (lectin determinants), which are the disaccharide as all or part of the determinants and of GalNAc alpha 1-->Ser (Thr) of the peptide chain. A scheme of codes for lectin determinants is illustrated as follows: (1) F (GalNAc alpha 1-->3GalNAc), Forssman specific disaccharide--Dolichos biflorus (DBL), Helix pomatia (HPL) and Wistaria floribunda (WFL) lectins. (2) A (GalNAc alpha 1-->3 Gal), blood group A specific disaccharide--Codium fragile subspecies tomentosoides (CFT), Soy bean (SBL), Vicia villosa-A4 (VVL-A4), and Wistaria floribunda (WFL) lectins. (3) Tn (GalNAc alpha 1-->Ser (Thr) of the protein core)--Vicia villosa B4 (VVL-B4), Salvia sclarea (SSL), Maclura pomifera (MPL), Bauhinia purpurea alba (BPL) and Artocarpus integrifolia (Jacalin, AIL). (4) T (Gal beta 1-->3GalNAc), the mucin type sugar sequences on the human erythrocyte membrane(T alpha), T antigen or the disaccharides at the terminal nonreducing end of gangliosides (T beta)--Peanut (PNA), Bauhinia purpurea alba (BPL), Maclura pomifera (MPL), Sophora japonica (SJL), Artocarpus lakoocha (Artocarpin) lectins and Abrus precatorius agglutinin (APA).(5) I and II (Gal beta 1-->3(4)GlcNAc)--the disaccharide residue at the nonreducing end of the carbohydrate chains derived from either N- or O-glycosidic linkage--Ricinus communis agglutinin (RCA1), Datura stramonium (TAL, Thorn apple), Erythrina cristagalli (ECL, Coral tree), and Geodia cydonium (GCL). (6) B (Gal alpha 1-->3Gal), human blood group B specific disaccharide--Griffonia(Banderiaea) simplicifolia B4 (GSI-B4). (7) E (Gal alpha 1-->4Gal), receptors for pathogenic E. coli agglutinin, Shiga toxin and Mistletoe toxic lectin-I (ML-I) and abrin-a.