DNA restriction-site polymorphisms associated with the alpha 1-antitrypsin gene.

Restriction-site variation in and around the alpha 1-antitrypsin gene has been studied using two genomic probes. With use of restriction enzymes SstI, MspI, and AvaII, three polymorphic sites have been described with a 4.6-kb probe in the 5' portion of the gene. With use of a 6.5-kb probe, polymorphisms in the coding and 3' regions of the gene have been detected with AvaII, MaeIII, and TaqI. All of these polymorphisms are of sufficiently high frequency to be useful in genetic mapping studies. The polymorphisms with AvaII and MaeIII (6.5-kb probe) are particularly useful for prenatal diagnosis. PI types and M subtypes tend to be associated with specific DNA haplotypes; there are two different types of DNA haplotypes associated with PI M1. The extent of linkage disequilibrium differs throughout the region of the alpha 1-antitrypsin gene.     

Facilitating care of patients with HIV infection by hospital and primary care teams.

To complement the role of primary care teams working with patients with HIV disease and AIDS within greater London and to ease the load on the special hospital units a home support team was developed. It comprises six specialist nurses, a general practitioner trained medical officer, and a receptionist and is funded from regional and district sources and charities. A nurse is available for out of hours and emergency weekend calls, with support from the patient''s general practitioner or the attached medical officer. During the first 18 months 249 patients were seen; the mean duration of care was five months. Nearly a third (18/50, 30%) of patients who were terminally ill died at home. The team''s activities included practical nursing care, emotional support for carers and patients, and advice and guidance to primary care teams. Problems in providing care in patients'' homes included issues relating to confidentiality and 24 hour cover. With the increasing incidence of HIV infection the home support team may be a useful model for care of large numbers of patients with symptomatic HIV disease, especially in large urban areas.     

Optical difference spectrum of the electron acceptor Ao in photosystem I

Optical measurements were made during low temperature photoreduction of photosystem I acceptors, A₁ and A₀. In the presence of a significant amount ofA₁ (detected by EPR), no absorbance changes occurred between 750-350 nm, indicating that this species is not a chlorophyll or pheophytin molecule. Spectral changes in this region that may be correlated with the appearance of A⁻₀, suggest that this component is a chlorophyll a anion monomer. The species is present in reaction centres in a ratio of 0.94 A_o/P700.

Photosystem I Primary acceptor Optical difference spectrum Chlorophyll a monomer     

Lymphocyte function in experimental African trypanosomiasis. VII. Loss of antigen-nonspecific suppressor-T-cell activity

The extent of immunosuppression occurring in mice infected with the pathogenic African trypanosomes was studied. Spleen cells from Trypanosoma rhodesiense-infected C57BL/6J mice were tested for antigen-nonspecific suppressor-T-cell (Ts) activity after concanavalin A (Con A) treatment in vitro. After exposure to Con A, control and infected mouse spleen cells were added to responder spleen cell cultures stimulated with sheep erythrocytes (SRBC). Assays for the resultant plaque-forming cell responses to SRBC revealed that antigen-nonspecific Ts activity was lost during the first week of infection. Changes in infected mouse T-cell subpopulations, including a terminal loss of Lyt 2.2+ cells, accompanied but did not precede the demonstrable loss of Ts function. Splenic suppressor macrophages which arise during infections with T. rhodesiense also did not seem to be associated with the loss of antigen-nonspecific Ts activity. It is concluded that the generalized immunosuppression associated with experimental African trypanosomiasis extends to the mitogen-induced Ts population.     

Evolutionary analysis of the multigene pregnancy-specific β1-Glycoprotein family: Separation of historical and nonhistorical signals

The pregnancy-specific ₁-glycoproteins (PSG) form a large family of closely related proteins. Using newly developed methods of sequence analysis, in combination with protein modeling, we provide a framework for investigating the evolution and biological function of genes like the PSG. Evolutionary trees, based on C-terminal sequence, group PSG genes in a manner consistent with their genomic organization. Trees constructed using the N-terminal domain sequences are unreliable as an indicator of phylogeny because of non-neutral processes of sequence change. During duplication of the PSG genes, evolutionary pressures have resulted in a gradient of constrained change across each gene. The N-terminal domains show a nonrandom pattern of amino acid substitutions clustered in the immunoglobulin complementarity-determining region (CDR)-like regions, which appear to be important in the function of the protein.     

Variation in Salmonella core lipopolysaccharide as detected by the monoclonal antibody M105

L.P. MANSFIELD, E. BILLETT, E. OLSEN AND S.J. FORSYTHE. 1996. The lipopolysaccharide antigenicity of 22 Salmonella strains (representing nine serogroups) and four non-salmonellae Enterobacteriaceae to the Salmonella genus specific monoclonal antibody M105 was analysed. The monoclonal antibody M105 reacted with all 22 Salmonella strains. Probing SDS-PAGE separated LPS molecules with MAb M105 revealed that the antibody reacted with the core region of all Salmonella serovars. However, no reaction was obtained to the long-chain LPS of serovars O ( Salm. adelaide and Salm. ealing ), C₁ ( Salm. infantis, Salm. livingstone and Salm. virchow ) or Salm. arizonae . It is plausible that the presence of a second core antigenic type results in the lack of reaction between long-chain LPS and the Salmonella genus specific monoclonal antibody M105.     

Chemotaxis ofAeromonas hydrophila to the surface mucus of fish

Isolates ofAeromonas hydrophila from various sources show different chemotactic responses to mucus from the surface of freshwater fish. Some isolates were nonchemotactic to fish surface mucus. Isolates ofA. hydrophila from fish lesions had a significantly higher chemotactic index than isolates ofA. hydrophila from water. Maximum chemotactic responses occurred more often to diluted fish mucus than to undiluted samples. Fish which were experimentally stressed did not produce mucus that was more or less chemotactic than that of unstressed fish. Fish with red-sore lesions produced surface mucus which was not chemotactic toA. hydrophila. Differences between fish, for any isolate, were also not significant. The chemotactic substance(s) in fish mucus has a molecular weight of approximately 100,000 and did not appear to be labile when heated to 56°C.