Evidence for the expression of two distinct MHC class II DRβ like molecules in the sheep

This study used monoclonal antibodies to sheep MHC class II molecules as well as an L cell transfectant (T8.1) which expresses DRA and DRB genes to show that two distinct DRβ chains are expressed in the sheep. Two anti-β chain specific monoclonal antibodies VPM37 and VPM43 react with DR antigen but not DQ antigen by ELISA. These two antibodies do not react with the DRβ chain expressed in the T8.1 cell line. Two-dimensional immunoblotting shows that these antibodies recognize a subgroup of the spots recognized by the DR-specific monoclonal antibody VPM57 which does react with the T8.1 β chain. Amino-terminal sequence analysis of the α chain associated with VPM37β chain shows that this α chain is homologous to the human DRα chain strongly indicating that the β chain is DR-like. VPM37 and VPM43 are shown to be directed against different epitopes on sheep MHC class II molecules so it is highly unlikely that the data can be explained by the presence of posttranslational modifications or the existence of a very common allele. These data provide clear evidence for the expression of two distinct DRP chains in the sheep.     

Polymer Coated Urea in Turfgrass Maintains Vigor and Mitigates Nitrogen's Environmental Impacts

Polymer coated urea (PCU) is a N fertilizer which, when added to moist soil, uses temperature-controlled diffusion to regulate N release in matching plant demand and mitigate environmental losses. Uncoated urea and PCU were compared for their effects on gaseous (N₂O and NH₃) and aqueous (NO₃^-) N environmental losses in cool season turfgrass over the entire PCU N-release period. Field studies were conducted on established turfgrass sites with mixtures of Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.) in sand and loam soils. Each study compared 0 kg N ha^-1 (control) to 200 kg N ha^-1 applied as either urea or PCU (Duration 45CR®). Application of urea resulted in 127–476% more evolution of measured N₂O into the atmosphere, whereas PCU was similar to background emission levels from the control. Compared to urea, PCU reduced NH₃ emissions by 41–49% and N₂O emissions by 45–73%, while improving growth and verdure compared to the control. Differences in leachate NO₃^- among urea, PCU and control were inconclusive. This improvement in N management to ameliorate atmospheric losses of N using PCU will contribute to conserving natural resources and mitigating environmental impacts of N fertilization in turfgrass.     

Tapetoretinal Degeneration in Childhood Presenting as a Disturbance of Behaviour

Four children presented at the age of 6 years with progressive disturbances of behaviour due to increasing visual handicap. In three of them routine ophthalmological examination was carried out in the early stages, but no objective evidence of eye disease was found. The severity and nature of the visual defect and its causal relationship to the behaviour disorder went unrecognized for periods ranging from 18 to 30 months. Eventually the development of retinal changes enabled a diagnosis of tapetoretinal degeneration to be made which was confirmed by the finding of extinction of the electroretinographic response. Transfer of the children to schools for the visually handicapped resulted in improvement in their behaviour disorder.Electroretinography is of great importance in the early diagnosis of juvenile tapetoretinal degeneration.     

Effects of 1-ethynylpyrene and related inhibitors of P450 isozymes upon benzo[a]pyrene metabolism by liver microsomes

The effects of three aryl acetylenes, 1-ethynylpyrene (EP), 2-ethynylnaphthalene (EN) and 3-ethynylperylene (EPE), upon the metabolism of benzo[a]pyrene (BaP) by microsomes isolated from rat liver were investigated. These aryl acetylenes all inhibited the total metabolism of BaP. Formation of BaP 7,8-dihydrodiol and BaP tetrol products by microsomal preparations from rats that had been pretreated with 3-methylcholanthrene (3MC) were preferentially inhibited. The effects of EP upon the metabolism of BaP 7,8-dihydrodiol by microsomes from rat liver were also studied. This aryl acetylene strongly inhibited the formation of BaP tetrols from BaP 7,8-dihydrodiol by liver microsomes both from untreated rats and from rats pretreated with 3MC, but enhanced the conversion of the BaP dihydrodiol into other metabolites.