Evaluation of the humoral immune response of CD rats following a 2-week exposure to the pesticide carbaryl by the oral, dermal, or inhalation routes

The objective of this study was to examine the immunotoxicological effects of the methyl-carbamate pesticide carbaryl via the oral, dermal, or inhalation routes. Male CD rats were exposed to carbaryl 5 d/wk for a 2-wk period. During nose-only inhalation exposures, rats received either 36, 137, or 335 mg/m3 carbaryl in acetone for 6 h. Air only and acetone/air controls were run concurrently. Orally exposed animals received either 1 ml corn oil or 10, 25, or 50 mg/kg carbaryl, while dermally exposed animals received either 2 ml acetone or 100, 500, or 1000 mg/kg carbaryl on their dorsal flank for 6 h. Four days prior to sacrifice, animals from all exposure groups were injected iv with 2 x 10(8) sheep red blood cells (SRBC). The primary immunoglobulin M (IgM) humoral immune response to SRBC was then assessed by measuring SRBC-specific antibody-forming cells (AFC) and levels of serum anti-SRBC IgM antibody, respectively, using the hemolytic plaque assay and an enzyme-linked immunosorbent assay. Individual body weights, spleen, thymus, and liver weights, spleen cell number, and red and white blood cell (RBC, WBC) counts were obtained for each animal. Following nose-only inhalation exposures, dose-dependent decreases in thymus weights, spleen cell number, AFC/spleen, AFC/10(6) splenocytes, and serum levels of SRBC-specific IgM antibody were observed. Significant decreases of 33, 57, and 22% in spleen cell number, AFC/spleen, and thymus weight, respectively, were found at the 335 mg/m3 exposure level. Animals exposed orally to 25 mg/kg carbaryl had a 34% decrease in WBC counts. A 34% decrease in WBC and a 13% increase in RBC counts were observed at the 50 mg/kg oral dose. Significant decreases in liver weights ranging from 11 to 13% were found at all oral exposure levels. Dermal exposure to carbaryl revealed no significant toxicological effects. Results indicate that humoral immune suppression was observed following inhalation, but not following oral or dermal exposures to carbaryl. Immunotoxicological studies evaluating pesticides need to consider relevant exposure routes and dosages for appropriate risk assessment procedures and exposure limits to be established.     

Room-temperature oxidation of reduced Cu/ZnO surfaces by lattice oxygen diffusion

At room temperature in the absence of gas-phase oxygen, reduced Cu on Cu/ZnO extracts oxygen from the ZnO lattice to reoxidize the surface. After 120 min at room temperature, diffusion of lattice oxygen reoxidizes reduced Cu/ZnO to 3% of its completely oxidized state. When gas-phase oxygen is present, it promotes the partial reoxidation of the reduced Cu/ZnO surface at room-temperature.     

Effect of temperature and pH value on the growth-rate constants of nitrifying bacteria in the activated-sludge process

The specific growth rates of nitrifying organisms were determined under non-equilibrium conditions in laboratory-scale activated sludge plants at three temperatures and six pH values. The highest growth rate for the first stage (to nitrite) was 0.61 d⁻¹; no nitrification was observed over a 7 week period at pH 6.0 at any temperature, indicating a μ value of <0.06 d⁻¹. Fewer data were obtained for the second stage (to nitrate); in all but one of ten comparisons the specific growth rate was lower (by an average of 16%) than for the first stage. The effects of temperature and pH value were not as expected probably because of greater effects resulting from the differences in composition and strength of the sewages used.It is shown that calculations of μ from simple measurements made on full-scale plants can give an early warning of harmful changes in the aeration tank well before the concentration of ammonia in the effluent increases.     

Posterior column ataxia with retinitis pigmentosa (AXPC1) maps to chromosome 1q31-q32

OBJECTIVE: To establish a genetic linkage between highly polymorphic microsatellite loci and the disease locus responsible for an autosomal recessive neurodegenerative syndrome that causes posterior column ataxia and retinitis pigmentosa. BACKGROUND: The authors reported previously a genetic syndrome that causes visual impairment, proprioceptive loss, sensory ataxia, and areflexia in affected individuals from a large, inbred family belonging to a sectarian population that has been genetically semi-isolated from mainstream society for several centuries. METHODS: To find the disease locus responsible for this condition, the authors performed a genome-wide search using genetic loci spaced at 10 to 20-cM intervals spanning human chromosomes (chr) 1-22. Pairwise linkage analysis, multipoint linkage analysis, and haplotype reconstruction were used to delineate the candidate region containing the disease gene. RESULTS: After testing 226 loci that covered the entire genome, the authors identified a maximum lod score of 8.94 at a recombination fraction of 0.00 for locus D1S2692. Additional analyses placed the disease gene, AXPC1, in an 8.3-cM interval flanked by markers D1S2692 and D1S414 on chr 1q31-q32. CONCLUSIONS: This study suggests that a single genetic mutation can cause selective degeneration of the posterior columns of the spinal cord and retina. Finding the gene responsible for this syndrome may increase our understanding of the molecular basis of diseases that affect sensory neurons.     

The Effect of Overbank Flow in a Meandering River on its Conveyance and the Transport of Graded Sediments

A large-scale model hydraulic study of inbank and over-bank river flow, using a regular sinuous river channel with a mobile bed, was carried out in the Flood Channel Facility at HR Wallingford, UK. The selected sediment had a wide range of particle sizes present over the 'fine sand to coarse sand'range. Flow velocity, local and global sediment transport rates, and channel conveyance were all measured. The resulting bed forms were determined and used to explain the secondary circulation in the sinuous channel as well as the size sorting of the sediment. The paper gives an early overview of this major project.     

Measuring the Magnetic Flux Density in the CMS Steel Yoke

The Compact Muon Solenoid (CMS) is a general purpose detector, designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with 6-m-diameter by 12.5-m-length free bore, enclosed inside a 10,000-ton return yoke made of construction steel. The return yoke consists of five dodecagonal three-layered barrel wheels and four end-cap disks at each end comprised of steel blocks up to 620 mm thick, which serve as the absorber plates of the muon detection system. Accurate characterization of the magnetic field everywhere in the CMS detector is required. To measure the field in and around the steel, a system of 22 flux loops and 82 3-D Hall sensors is installed on the return yoke blocks. Fast discharges of the solenoid (190 s time-constant) made during the CMS magnet surface commissioning test at the solenoid central fields of 2.64, 3.16, 3.68 and 4.01 T were used to induce voltages in the flux loops. The voltages are measured on-line and integrated off-line to obtain the magnetic flux in the steel yoke close to the muon chambers at full excitations of the solenoid. The 3-D Hall sensors installed on the steel–air interfaces give supplementary information on the components of magnetic field and permit to estimate the remanent field in steel to be added to the magnetic flux density obtained by the voltages integration. A TOSCA 3-D model of the CMS magnet is developed to describe the magnetic field everywhere outside the tracking volume measured with the field-mapping machine. The results of the measurements and calculations are presented, compared, and discussed.     

Evidence that a gene for essential tremor maps to chromosome 2p in four families

In this Journal, we previously reported genetic linkage between loci on chromosome (chr)2p(ETM) and dominantly inherited essential tremor (ET) in a large American kindred of Czech ancestry. Other investigators reported another ET susceptibility locus on chr 3q (FET1) which accounted for over half of the Icelandic families that were studied. We now report evidence for linkage to the ETM locus in three additional, unrelated American families with ET and exclude the FET1 locus in these families. Fine mapping results, using an "affecteds-only" model in all four American families, demonstrate positive combined pairwise lod scores (Z) at the ETM locus with aZ(max) = 5.94 at a recombination fraction (theta) = 0.00 for locus D2S220. Haplotype reconstruction places the ETM gene in a 9.10 cM interval between the D2S224 and D2S405 loci. Multipoint linkage analysis suggests that the ETM gene is in the 2.18 cM interval between loci D2S2150 and D2S220 with a Z(max) = 8.12. These findings may facilitate the search for a gene that causes ET and may further our understanding of other disorders that are associated with tremor [corrected].