Targeted gene disruption of murine CD7

CD7 is a 40 kDa type I transmembrane glycoprotein member of the Ig superfamily. CD7 is a marker of mature human T cells and NK cells, and is expressed early in their development. Cross-linking CD7 positively modulates T cell and NK cell activity as measured by calcium fluxes, expression of adhesion molecules, cytokine secretion and proliferation. CD7 associates directly with phosphoinositol 3'-kinase, and CD7 ligation induces production of D-3 phosphoinositides and tyrosine phosphorylation. Severe combined immunodeficiency has been associated with a lack of lymphocyte surface CD7. The CD7 ligand is unknown. The murine CD7 homolog is encoded by a single gene on chromosome 11. In order to characterize the role of CD7 in lymphocyte development and function we have eliminated the CD7 gene by targeted disruption. CD7- deficient mice display normal histology of thymus and spleen, normal lymphocyte populations in primary and secondary lymphoid tissues, and normal serum Ig levels. Specific antibody responses after immunization with T-dependent and T-independent antigens are equivalent in wild-type and CD7 knockout mice. CD7-deficient lymphocytes respond normally to T cell mitogenic and allogeneic stimuli, and display normal NK cell cytotoxicity.      

Use of a commercial reagent leads to reduced germ tube production by Candida dubliniensis

The goal of this study was to determine the factor(s) explaining our inability to detect Candida dubliniensis. When germ tube-positive yeasts were tested for C. dubliniensis, no C. dubliniensis was detected; however, 58 C. dubliniensis strains were detected when germ tube-negative Candida albicans strains were tested further. Since all 58 C. dubliniensis strains detected were germ tube negative, these data implied that false-negative germ tube tests occurred with germ tube solution (GTS; Remel, Lenexa, KS). All 41 known C. dubliniensis strains tested were negative with GTS, whereas 40 were positive with rabbit serum (RS; Sigma-Aldrich, St. Louis, MO). Results for C. albicans were equivalent in GTS and RS. In conclusion, GTS cannot be used for the detection of C. dubliniensis, and switching from yeast to hyphae in C. dubliniensis is more restricted than in C. albicans.     

Gamma-Ray Induction of Malignant Tumors in Rats

Sources of protracted gamma radiation adjacent to bone were found to induceosteogenic sarcoma in half of the exposed males. Osteogenic sarcomas appeared in 3 males remote from the radioactive sources and may not have been radiation induced. Some tumors were small enough so that the site of origin could be determined accurately: some arose from endosteum, others from periosteum. Although portions of the skeleton in the female rats incidentally received doses of over 20,000 rads, no osteogenic sarcomas developed in them. Parauterine sources induced adenocarcinoma of the endometrium in 14 of 32 rats (44%). The incidence of carcinoma of the ovary (12%) was lower than expected. Carcinomas of the breast were frequent, but often distant from the source. Increased total dose, which was usually related to length of time of exposure, produced an increased incidence of cancer and a shortening of the latent period. However, extremely high doses (over a million rads to bone and hundreds of thousands to the uterus) at times failed to induce cancers.     

Epstein-Barr-virus-transformed lymphoblastoid cell lines derived from patients with X-linked agammaglobulinaemia and Wiskott-Aldrich syndrome: responses to B cell growth and differentiation factors.

Epstein-Barr-virus-transformed B lymphoblastoid cell lines (EBV-transformed LCL) from three patients with X-linked agammaglobulinaemia (XLA), six patients with Wiskott-Aldrich Syndrome (WAS), and seven normal donors, were tested for growth and differentiation in response to human recombinant IL-4, a commercially available, low molecular weight B cell growth factor (BCGFlow), and B cell differentiation factor (BCDF) secreted by the T24 cell line, now known to be IL-6. Proliferation (3H-TdR uptake) by EBV-transformed LCL from both XLA and WAS patients in response to BCGFlow was similar to that obtained with the normal cell lines. In addition, three normal and three WAS, but none of the XLA EBV-transformed LCL, proliferated a little in response to IL-4. All the normal B cell lines secreted IgM, and six out of the seven secreted IgG in response to BCGFlow and BCDF. A similar pattern of response was obtained with the WAS EBV-transformed LCL (6/6 secreted IgM and 4/6 secreted IgG). Several of the normal and WAS EBV-transformed LCL also secreted IgM and IgG in response to IL-4. In contrast, the lines from the XLA patients were abnormal. One secreted large amounts of IgM and two secreted small amounts, but none of the XLA lines secreted IgG constitutively or in response to any of the factors (IL-4, BCDF). The lack of detectable IgG secretion by the XLA lines was probably due to an absence of precommitted IgG B cell precursors transformed by EBV rather than an intrinsic inability to respond to BCGF and BCDF. All of the lines, including those derived from XLA patients, were shown to secrete B cell growth and differentiation factors detected on indicator B cell lines. These results suggest that the abnormal X-linked genes responsible for XLA and WAS do not interfere with B cell responses to B cell growth and differentiation factors.     

Some determinants of the locomotory behaviour of phagocytes and lymphocytes in vitro

In this review, we discuss some physical and chemical determinants of locomotor behaviour of phagocytic cells and lymphocytes as studied in visual assays, paying particular attention to the following points. (a) A distinction is made between chemokinesis and other forms of kinesis. We propose that the term chemokinesis be reserved for responses resulting from selective recognition of chemical substances. Many kineses in leucocytes may not involve such recognition, but may result from a variety of physical factors, such as those that alter the adhesiveness between cell and substratum. (b) Neutrophils moving in aligned gels of collagen or fibrin show contact guidance of locomotion, i.e. bidirectional movement along the axis of alignment of the fibres of the gel. Thus neutrophils show directional locomotion not only in chemotactic gradients but also in response to physical properties of the substratum. (c) Lymphocytes adhere poorly and move poorly on 2D protein coated substrata. However they move rapidly through 3D collagen gels. This locomotion may be independent of adhesion since lymphocytes may gain traction for locomotion by expanding pseudopods into gaps in the gel matrix, then using the pseudopod as an anchor for subsequent locomotion in any direction.     

Intestinal hypersensitivity reactions in the rat. I. Uptake of intact protein, permeability to sugars and their correlation with mucosal mast-cell activation.

We have confirmed previous observations that intestinal anaphylaxis induced in rats previously sensitized to ovalbumin (OVA) is associated with an increased uptake of an unrelated 'bystander' protein, bovine serum albumin (BSA) fed 1 hr previously. In this study, this enhanced protein uptake was associated with an increased lactulose/rhamnose excretion ratio after administration of these sugars, although there was no correlation between the two measurements. One hour after antigen challenge the serum levels of rat mast-cell protease II (RMCPII), a specific marker for mucosal mast-cell secretion, were significantly higher than both the pre-challenge levels and those of sham-challenged controls (P less than 0.002). There was a significant positive correlation between the serum levels of RMCPII and the lactulose/rhamnose excretion ratios (P less than 0.05), but no such correlation existed between RMCPII and BSA levels in the challenged rats. In other studies the urinary lactulose/rhamnose ratios of rats with cetrimide-induced gut damage were found to be significantly increased, although BSA uptake into the serum remained unaltered. We conclude that there is no simple correlation between gut permeation of low-molecular weight sugars and and the uptake of macromolecular proteins.     

SKALP/elafin gene polymorphisms are not associated with pustular forms of psoriasis

Psoriasis is a multifactorial skin disease characterised by epidermal abnormalities and infiltration by lymphocytes and polymorphonuclear leukocytes (PMN). Skin-derived antileukoproteinase (SKALP), also known as elafin, is a potent inhibitor of human leukocyte elastase and proteinase 3, two PMN-derived proteinases implicated in tissue destruction and leukocyte migration. We have shown that, at least at the protein level, SKALP is significantly decreased in lesional skin of patients with pustular psoriasis compared with plaque-type psoriasis. This finding raised the possibility that SKALP could be one of the candidate genes for pustular forms of psoriasis. We therefore performed single strand conformation polymorphism (SSCP) analysis on the SKALP gene to screen for mutations/polymorphisms in the exons of 30 patients with plaque-type psoriasis, 15 patients with pustular psoriasis and 48 healthy controls. In exon 1 a polymorphism was detected at position + 43 relative to the translation start site, resulting in a substitution of threonine for alanine in the signal peptide. In the promoter region a dinucleotide repeat polymorphism was identified. Both polymorphisms were not associated with pustular psoriasis, or psoriasis in general. Our data indicate that the decrease in SKALP activity in pustular psoriasis is not caused by mutations in the coding region of the gene, and that there is no allelic association between pustular psoriasis and SKALP gene polymorphisms.     

<Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> Ats1p interacts with Nap1p,a cytoplasmic protein that controls bud morphogenesis

Saccharomyces cerevisiae ATS1 (-tubulin suppressor 1) was originally identified as a high-copy suppressor of class two -tubulin mutations and was proposed to have a regulatory role in coordinating the microtubule state with the cell cycle. Here, we show that Ats1p interacts with Nap1p, a cytoplasmic protein that regulates the activity of the Cdc28p/Clb2p complex. Loss of Nap1p results in a delayed switch from polar to isotropic bud growth. The delayed switch results in elongated buds. Nap1p and Ats1p interact in two-hybrid and co-immunoprecipitation assays. Both nap1 and ats1 cells have a Clb2p-dependent elongated bud morphology. Deletion of ATS1 partially suppresses the elongated bud morphology and benomyl resistance of nap1 mutants. Our results suggest Ats1p might regulate coordination of the microtubule state with the cell cycle through an interaction with Nap1p.Communicated by S. Hohmann     

The mouse Mid1 gene: implications for the pathogenesis of Opitz syndrome and the evolution of the mammalian pseudoautosomal region

We have recently reported isolation of the gene responsible for X- linked Opitz G/BBB syndrome, a defect of midline development. MID1 is located on the distal short arm of the human X chromosome (Xp22. 3) and encodes a novel member of the B box family of zinc finger proteins. We have now cloned the murine homolog of MID1 and performed preliminary expression studies during development. Mid1 expression in undifferentiated cells in the central nervous, gastrointestinal and urogenital systems suggests that abnormal cell proliferation may underlie the defect in midline development characteristic of Opitz syndrome. We have also found that Mid1 is located within the mouse pseudoautosomal region (PAR) in Mus musculus , while it seems to be X- specific in Mus spretus. Therefore, Mid1 is likely to be a recent acquisition of the M. musculus PAR. Genetic and FISH analyses also demonstrated a high frequency of unequal crossovers in the murine PAR, creating spontaneous deletion/duplication events involving Mid1. These data provide evidence for the first time that genetic instability of the PAR may affect functionally important genes. In addition, we show that MID1 is the first example of a gene subject to X-inactivation in man while escaping it in mouse. These data contribute to a better understanding of the molecular content and evolution of the rodent PAR.      

The salivary microbiota as a diagnostic indicator of oral cancer: A descriptive,non-randomized study of cancer-free and oral squamous cell carcinoma subjects

Background  

The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls.