Expression of Lex antigen in Schistosoma japonicum and S.haematobium and immune responses to Lex in infected animals: lack of Lex expression in other trematodes and nematodes

Adults of the human parasitic trematode Schistosoma mansoni, which causes hepatosplenic/intestinal complications in humans, synthesize glycoconjugates containing the Lewis x (Lex) Galbeta1-->4(Fucalpha1-- >3)GlcNAcbeta1-->R, but not sialyl Lewis x (sLex), antigen. We now report on our analyses of Lexand sLexexpression in S.haematobium and S.japonicum, which are two other major species of human schistosomes that cause disease, and the possible autoimmunity to these antigens in infected individuals. Antigen expression was evaluated by both ELISA and Western blot analyses of detergent extracts of parasites using monoclonal antibodies. Several high molecular weight glycoproteins in both S. haematobium and S. japonicum contain the Lexantigen, but no sialyl Lexantigen was detected. In addition, sera from humans and rodents infected with S.haematobium and S.japonicum contain antibodies reactive with Lex. These results led us to investigate whether Lexantigens are expressed in other helminths, including the parasitic trematode Fasciola hepatica , the parasitic nematode Dirofilaria immitis (dog heartworm), the ruminant nematode Haemonchus contortus , and the free-living nematode Caenorhabditis elegans . Neither Lexnor sialyl-Lexis detectable in these other helminths. Furthermore, none of the helminths, including schistosomes, express Lea, Leb, Ley, or the H- type 1 antigen. However, several glycoproteins from all helminths analyzed are bound by Lotus tetragonolobus agglutinin , which binds Fucalpha1-->3GlcNAc, and Wisteria floribunda agglutinin, which binds GalNAcbeta1-->4GlcNAc (lacdiNAc or LDN). Thus, schistosomes may be unique among helminths in expressing the Lexantigen, whereas many different helminths may express alpha1,3-fucosylated glycans and the LDN motif.      

Kinetics of the in vitro lymphocyte response to myelin basic protein in the the Lewis and Brown Norway strains of rat.

Several parameters of the in vitro lymphocyte proliferative response to myelin basic protein (BP) in Lewis (Le) and Brown Norway (BN) rats were examined. The results demonstrate that BN rats, a strain normally resistant to BP-induced experimental allergic encephalomyelitis, and Le rats, a strain readily susceptible to the disease, have similar patterns of the proliferative response to BP. An important difference, however, is that BN lymphocytes, although responding significantly to BP, are unable to proliferate to the same level as Le lymphocytes. In experiments measuring the lymphocyte response as a function of antigenic stimulus, days of culture, or type of adjuvant used, the BN rat peak response was in general 70% or less of the Le rat peak response. Furthermore, the BN lymphocyte response was reduced when B cells were removed whereas there was no effect in the Le rat. A negative feedback mechanism, possibly suppressor cells, has been suggested to explain these differences.     

Immunity of children to diphtheria,tetanus, and poliomyelitis.

A survey of titres of diphtheria and tetanus antitoxins and of antibodies to polioviruses in the sera of 291 schoolchildren aged 15, 11, and 7 years showed that high immunisation rates can evoke protective concentrations of tetanus antitoxin in 98% of children and protective levels of the antibodies to diphtheria and all three types of poliomyelitis in 85% of children. Reinforcing immunisation at school entry appeared to be necessary to maintain adequate titres of diphtheria antitoxin in children up to 15 years of age, not essential to maintain adequate titres of tetanus antitoxin, and to have little effect on the titres of antibodies to poliomyelitis.     

Effect of trypsin on mouse mammary tumor virus.

Undisrupted mouse mammary tumor virus (MuMTV) derived from the milk of of RIII mice has been analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electron microscopy after treatment with insolubilized trypsin. No alterations were found in viral fine structure by either freeze-etch or negative-stain electron microscopy. No alterations were found in the ability of trypsinized virus to compete in a radioimmune assay for viral antigens. Infectivity experiments indicate no significant differences in the ability of treated virus to infect C57Bl mice. However, significant differences were observed in polypeptide composition. The intensely periodic acid-Schiff-positive band, gp140, was shown by galactose oxidase-borotritide labeling to be degraded into a fragment of 125,000 molecular weight. The major glycoprotein, gp55, was split into fragments of 36,000 and 23,000 molecular weight, both of which stained with periodic acid-Schiff stain. Gp68 was removed from the virus. Experiments with purified, iodinated gp55 showed that the trypsin-induced fragments of gp55 were immunologically active. We conclude that: (i) certain glycoproteins at the surface of MuMTV are accessible to an insoluble form of trypsin, (ii) the trypsin causes a nick in the polypeptide chain without affecting the configuration of the molecule; (iii) the nicked molecules remain bound to the virus; and (iv) the presence of these nicked molecules does not interfere with the biological or antigenic expression of virus function.     

Community,mobility and racism in a semi-rural area: Comparing minority experience in East Kent

Much research into community, racism and racialization has been conducted in metropolitan urban settings. It is only recently that race in rural areas has received some attention. A key theme of existing research on race in rural areas has focused on the issue of racial violence. Drawing on interviews with a variety of ethnic minority groups in East Kent the article will focus on broader issues of race and ethnicity in a semi-rural area. The study explores the meaning of race, ethnicity and belonging in the partially rural setting of East Kent, UK. The article will raise issues around the intersection of the regional and global, the problematic notion of “community”, and the fluidity of racialization in a setting in which many ethnic minorities were transitory and mobile. We conclude by highlighting the ways in which community, racism and racialization are embedded in differentiated discourses and processes.     

Solubility of fluoromethemoglobin S: effect of phosphate and temperature on polymerization

The polymerization properties of the fully liganded fluoromet derivative of hemoglobin S (FmetHb S) were investigated by electron microscopy and absorption spectroscopy. Polymerization progress curves, as measured by increasing sample turbidity at 700 nm, exhibit a delay time (t(d)) consistent with the double nucleation mechanism. The pattern of fiber growth, as monitored by electron microscopy, is also indicative of a heterogeneous nucleation process, and dimensions of the fibers were found to be comparable to that of deoxyHb S. The polymerization rate constant (1/t(d)) depends exponentially on Hb S concentration, and the size of the homogeneous and heterogeneous nuclei also depend on FmetHb S concentration. As for deoxyHb S, higher concentrations of protein and phosphate favor fiber formation, while lower temperatures inhibit polymerization. Solubility experiments reveal, however, that eight times more FmetHb S is required for polymerization. The current studies further show that reaction order is independent of phosphate concentration if Hb S activity and not concentration is considered. The allosteric effector, inositol hexaphosphate (IHP), promotes fiber formation, and temperature-dependent reaggregation of FmetHb S suggests that IHP stabilizes pregelation aggregates. These studies show that FmetHb S resembles deoxyHb S in many of its polymerization properties; however, IHP-bound FmetHb S potentially provides a unique avenue for future studies of the early stages of Hb S polymerization and the effect of tertiary and quaternary protein structure on the polymerization process.     

Preparation and crystal structure of the recombinant alpha(1)/alpha(2) catalytic heterodimer of bovine brain platelet-activating factor acetylhydrolase Ib

The intracellular form of mammalian platelet activating factor acetylhydrolase found in brain (PAF-AH Ib) is thought to play a critical role in control in neuronal migration during cortex development. This oligomeric complex consists of a homodimer of the 45 kDa (beta) LIS1 protein, the product of the causative gene for type I lissencephaly, and, depending on the developmental stage and species, one of three possible pairs of two homologous approximately 26 kDa alpha-subunits, which harbor all of the catalytic activity. The exact composition of this complex depends on the expression patterns of the alpha(1) and alpha(2) genes, exhibiting tissue specificity and developmental control. All three possible dimers (alpha(1)/alpha(1), alpha(1)/alpha(2) and alpha(2)/alpha(2)) were identified in tissues. The alpha(1)/alpha(2) heterodimer is thought to play an important role in fetal brain. The structure of the alpha(1)/alpha(1) homodimer was solved earlier in our laboratory at 1.7 A. We report here the preparation of recombinant alpha(1)/alpha(2) heterodimers using a specially constructed bi-cistronic expression vector. The approach may be useful in studies of other systems where pure heterodimers of recombinant proteins are required. The alpha(1)/alpha(2) dimer has been crystallized and its structure was solved at 2.1 A resolution by molecular replacement. These results set the stage for a detailed characterization of the PAF-AH Ib complex.     

Pitfalls in homozygosity mapping

There is much interest in use of identity-by-descent (IBD) methods to map genes, both in Mendelian and in complex disorders. Homozygosity mapping provides a rapid means of mapping autosomal recessive genes in consanguineous families by identifying chromosomal regions that show homozygous IBD segments in pooled samples. In this report, we point out some potential pitfalls that arose during the course of homozygosity mapping of the enhanced S-cone syndrome gene, resulting from (1) unexpected allelic heterogeneity, so that the region containing the disease locus was missed as a result of pooling; (2) identification of a homozygous IBD region unrelated to the disease locus; and (3) the potential for inflation of LOD scores as a result of underestimation of the extent of inbreeding, which Broman and Weber suggest may be quite common.