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Biomedical subjects

P A John

Publications and source records attributed to P A John.

At least 19 recordsLinked to original sources
PubMed1999

Enteroviral meningoencephalitis as a complication of X-linked hyper IgM syndrome.

We describe 5 children from 2 families with mutations in the CD40 ligand (CD40L) gene leading to absent expression of CD40L on activated CD4 cells. All subjects presented with interstitial pneumonia with low serum IgG and normal serum IgM. One child had normal and one child had elevated serum IgA. Four had confirmed Pneumocystis carinii pneumonia. In spite of intravenous immunoglobulin treatment yielding therapeutic serum immunoglobulin levels, 3 children had enteroviral encephalitis. When assessed by flow cytometry, the 3 surviving affected male children had absent CD40L expression on activated CD4(+) T cells. The affected children from both families were shown to have the same single nucleotide insertion (codon 131) resulting in frameshift and early termination within exon 4 (extracellular domain). This observation demonstrates that persistent enteroviral infection is not only observed in X-linked agammaglobulinemia but may also occur in patients with X-linked hyper IgM syndrome.

CD4-Positive T-Lymphocytes↗
PubMed1991

A streptococcal erythrogenic toxin preparation augments natural killer activity of peripheral blood mononuclear cells.

Natural killer (NK) activity in peripheral blood mononuclear cells is augmented by products released by two different strains of streptococci. This property is due at least in part to an erythrogenic toxin (ET). A preparation of physiologically active ET from strain NY5 group A beta-hemolytic streptococci and streptococcal products (SP) derived from the culture supernatants of ATCC strain 19165 group A streptococci were both potent inducers of NK activity. An anti-serum to ET reacted with two polypeptides in SP, one of which comigrated with ET when analyzed by SDS-PAGE. Using an affinity column with an antiserum to ET known to neutralize its mitogenic properties, the NK-enhancing activity of ET and SP was partly absorbed and was recovered upon elution. These findings suggest that immunologically related ETs in different streptococcal strains play a role in the activation of NK cells. This novel property of streptococci may feature in the pathogenesis of streptococcal infections and their protean manifestations.

Adsorption↗
PubMed1990

Serum factors in the progression of human immunodeficiency virus type 1 infection to AIDS.

We studied the prevalence of four serum factors in individuals at different stages of human immunodeficiency virus-1 (HIV-1) infection. Soluble interleukin-2 receptors (sIL-2R) were elevated in all antibody-positive groups compared with high-risk, antibody-negative controls. Paraproteins, usually of the IgG-kappa isotype, were found in the sera of a significant number of HIV-1-infected individuals as were antibodies to lymphocytes (ALAs). Serum factors that inhibit proliferation of peripheral blood mononuclear cells from healthy donors appear late in the course of infection and were associated with increasing clinical severity. Measurement of these factors may prove to be useful in defining the stages of infection and in predicting the appearance or exacerbation of symptoms. They may also play a role in the development of the HIV-1-induced immune defects that lead to the expression of clinical acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Preferential homing of tumor-infiltrating lymphocytes in tumor-bearing mice.

In view of the current interest in the use of lymphoid cells in adoptive immunotherapy of patients with advanced cancer, we have studied the homing patterns of various lymphoid effector cells in mammary-tumor-bearing mice. Single-cell suspensions of total splenocytes, natural killer (NK) cells, and lymphokine-activated killer (LAK) cells were prepared from the spleens of C3H/OuJ mice. Tumor-infiltrating lymphocytes (TIL) were isolated from mammary adenocarcinomas excised from retired breeder females of the same substrain. Effector cells were labeled with indium-111 and injected via a tail vein into female C3H/OuJ mice bearing one or more mammary tumors. Twenty-four hours after administration, total splenocytes, NK cells, and LAK cells distributed themselves evenly between normal mammary tissue and mammary adenocarcinomas. Only TIL had a higher concentration in tumors than in corresponding normal mammary tissue. The ability of the different lymphocyte preparations to lyse YAC-1 cells was determined by means of a 4-h 51Cr-release cytotoxicity assay. Cells harvested from LAK cell cultures and further enriched by centrifugation through a discontinuous Percoll gradient and interleukin-2 (IL-2)-stimulated TIL demonstrated the highest levels of cytotoxicity, while total splenocytes and fresh TIL were characterized by the lowest levels. Since IL-2-stimulated TIL were highly cytotoxic and exhibited better tumor localization than both NK cells and LAK cells in this system, they may be the lymphoid effectors of choice for adoptive immunotherapy of advanced cancer.

Adenocarcinoma↗
PubMed1988

The ergonomics of computer aided design within advanced manufacturing technology.

Many manufacturing companies have now awakened to the significance of computer aided design (CAD), although the majority of them have only been able to purchase computerised draughting systems of which only a subset produce direct manufacturing data. Such companies are moving steadily towards the concept of computer integrated manufacture (CIM), and this demands CAD to address more than draughting. CAD architects are thus having to rethink the basic specification of such systems, although they typically suffer from an insufficient understanding of the design task and have consequently been working with inadequate specifications. It is at this fundamental level that ergonomics has much to offer, making its contribution by encouraging user-centred design. The discussion considers the relationships between CAD and: the design task; the organisation and people; creativity; and artificial intelligence. It finishes with a summary of the contribution of ergonomics.

Journal Article↗
PubMed1987

Lysis of fresh murine mammary tumor cells by syngeneic natural killer cells and lymphokine-activated killer cells.

We have compared the ability of natural killer (NK) cells from two substrains of C3H mice that differ with respect to their susceptibility to the development of mammary adenocarcinomas to lyse fresh syngeneic mammary tumor cells. Single cell suspensions of mammary tumors from retired breeder females were used as targets in 22-h 51Cr-release cytotoxicity assays with syngeneic NK cells. Tumor cell suspensions were prepared by enzymatic digestion of finely minced tissue followed by centrifugation through a discontinuous Percoll gradient. Effector cells were prepared by passing spleen cells over nylon wool followed by centrifugation through Percoll fraction 7. Syngeneic NK cells had significant levels of lysis against 5/8 tumors studied. NK cells from low risk animals (C3Heb/FeJ) consistently demonstrated greater cytotoxicity against tumor cell preparations than did effectors from the high tumor substrain (C3H/OuJ). Study of cytocentrifuge preparations stained with Wright-Giemsa revealed that the two substrains were identical with respect to the number of azurophilic granules present in the cytoplasm of their NK cells. We have also shown that lymphokine-activated killer (LAK) cells can be generated from splenocytes in C3H mice. While LAK cells from both substrains were capable of lysing fresh syngeneic mammary tumor cells in vitro, LAK cells from the animals at high risk for the formation of mammary adenocarcinomas had greater cytotoxicity against tumor cell suspensions than LAK cells from the low tumor substrain.

Adenocarcinoma↗
PubMed1987

Soluble interleukin 2 receptors are elevated in patients with AIDS or at risk of developing AIDS.

Utilizing an enzyme-linked immunosorbent assay, we detected elevated serum levels of soluble interleukin 2 receptors (SIL-2R) in 73% of patients with acquired immunodeficiency syndrome (AIDS), 80% of AIDS-related complex patients, 78% of anti-HIV-positive lymphadenopathy syndrome patients, 85% of HIV-antibody-positive hemophiliacs, and 80% of anti-HIV-positive asymptomatic homosexual males, iv drug abusers, and heterosexual contacts. Of the subjects with no demonstrable antibody to HIV, 29% of hemophiliacs, 12% of adult homosexual males and iv drug abusers, and none of the patients with lymphadenopathy had elevated SIL-2R. Overall, only 5 of 40 antibody-negative "high-risk" individuals had SIL-2R values greater than the reference interval whereas 108 of 138 antibody-positive individuals had elevated values (chi 2 = 57.85, P less than 0.001).

AIDS-Related Complex↗
PubMed1986

The mechanism of enhancement of natural killer cell activity by soluble streptococcal products.

Products prepared from broth extracts of beta-hemolytic Group A streptococci activate human natural killer (NK) cells. The active moiety is likely a protein since the enhancing capability is destroyed by the proteolytic enzyme pronase, although not by trypsin. The enhancement in NK cytotoxicity is due at least in part to lymphokines, since normal peripheral blood mononuclear cells and T cells, upon incubation with streptococcal products (SP), release supernatant factors which augment NK activity. These cell culture supernatants contain interferons (IFN) as well as low levels of interleukin-2 (IL-2). Treatment of supernatants with anti-IFN antibodies has variable effects, depending on the donor cells used to produce the factors. In most cases, anti-IFN-gamma totally abrogates enhancement. Treatment of supernatants with antibodies to IFN-alpha modestly decreases enhancement of most donor cells; however, IFN-alpha appears not to be a major factor in SP-activated lymphokines. Pretreating effector cells with a monoclonal antibody directed against the IL-2 receptor (anti-Tac) usually reduces the supernatant effect. The combination of anti-Tac and anti-IFN-gamma totally nullifies enhancement. Thus T lymphocytes stimulated with streptococcal products augment NK activity at least in part by producing IFN-gamma and a factor whose activity is reduced by the interaction of the IL-2 receptor with anti-Tac.

Antibodies↗
PubMed1986

Decreased natural cytotoxicity in mice with high incidence of mammary adenocarcinoma.

In an attempt to gather evidence relevant to the question of whether natural killer (NK) cells play a role in resisting the development of primary tumors, we compared natural cell-mediated cytotoxicity in two substrains of C3H mice. Animals of the C3H/OuJ substrain are at high risk for the formation of mammary adenocarcinomas, while C3Heb/FeJ mice have a low incidence of such tumors. Natural cytotoxicity of splenic mononuclear cells was lower in the high-risk substrain, suggesting that a lesion in NK cell activity may be involved in murine mammary tumorigenesis. This difference was observed in animals between 5 and 37 weeks of age. There was no significant difference in the number of splenic large granular lymphocytes between the substrains. A significant difference in the ability of splenic lymphocytes from the two substrains to bind to the target cells was noted. Since the binding capacity of lymphocytes was greater in mice with reduced NK cell activity, the lesion in cytotoxicity may exist at a postbinding step in the lytic sequence. It is felt that the C3H mouse may provide a useful model for studying the role of NK cells in controlling primary tumors.

Adenocarcinoma↗
PubMed1985

Cellular targets of antilymphocyte antibodies in AIDS and LAS.

Many patients with acquired immune deficiency syndrome (AIDS) and lymphadenopathy syndrome (LAS) have serum antilymphocyte antibodies. The targets of these antibodies are neither sex nor HLA directed. There is disagreement about the cell subset at risk. We examined the cellular specificity of antilymphocyte antibodies from AIDS and LAS patients by microcytotoxicity on positively selected lymphocytes, by using double-labeling immunofluorescence, and by using well-characterized continuous cell lines as targets. We find that most AIDS/LAS patients have antibodies to T and B cells, that immunofluorescence is somewhat more sensitive than microcytotoxicity, and that the antibodies are directed to both T4+ and T4- lymphoid cells.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Antibodies to human T-cell lymphotropic virus-I membrane antigens and inverted T4/T8 ratios in hemophiliacs.

Antibodies to the membrane antigens of human T-cell lymphotropic virus-I (anti-HTLV-MA) have been detected in patients with the acquired immune deficiency syndrome (AIDS) and in patients with hemophilia. The authors examined sera from 71 AIDS patients and 46 hemophiliac children for the presence of anti-HTLV-MA using an indirect membrane immunofluorescence assay with flow cytometry analysis. Thirty-seven of the 71 (52%) AIDS patients and 7 of the 46 (15%) hemophiliac patients had high titered anti-HTLV-MA, using a T-lymphoid cell line infected with the leukemia virus. None of the 78 control subjects had high titered antibody. All seven hemophiliac patients with elevated anti-HTLV-MA used Factor VIII concentrates, and all had inverted T-lymphocyte helper-suppressor (T4 [Leu-3]/T8 [Leu 2]) ratios. No correlations were found between inverted T4/T8 ratios and antibody to cytomegalovirus, Toxoplasma gondii, or hepatitis B. This work supports contentions that HTLV-like organisms cause AIDS and that these organisms are transmitted by blood products such as Factor VIII concentrate.

Acquired Immunodeficiency Syndrome↗
PubMed1980

Human T lymphcytes are enriched for transfer factor.

Using a canine local skin assay, we tested transfer factor prepared from three subpopulations of human peripheral blood mononuclear cells. T lymphocytes are enriched for transfer factor whereas adherent cells and nonadherent/nonrosetting cells are not. Thus, it appears as if transfer factor is a T cell lymphokine, the immunobiology of which is still unclear.

Animals↗
PubMed1979

Mononuclear cells contain human transfer factor as assayed locally on the skin of dogs.

We prepared transfer factor from mononuclear (M) cells and polymorphonuclear (PMN) cells by sieving cell lysates through a P-2 Biogel column. By assaying column fractions by their ability to induce a local delayed-type reaction to antigen in canine skin, we determined that mononuclear cells most consistently contained skin activity. The elution patterns from P-2 Biogel of PMN or M-enriched preparations were less complex and much different from that seen with whole leukocytes.

Absorption↗