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O Bagasra

Publications and source records attributed to O Bagasra.

88 records · Page 5Linked to original sources
PubMed1985

Immune response of mice exposed to cis-diamminedichloroplatinum.

The effects of cis-diamminedichloroplatinum (CDDP) on lymphoid organs and the immune response of young and older adult mice were studied histologically and by functionally assessing the activity of various subpopulations of immune cells. Young adult mice (6-8 weeks old) treated with 2 mg/kg CDDP mounted an enhanced splenic plaque-forming cell (PFC) response to both sheep erythrocytes, a helper T-cell-dependent antigen (HD), and pneumococcal polysaccharide type III a helper T-cell-independent antigen (HI). Older adult mice (18-22 weeks old) treated in the same way exhibited an equally enhanced PFC response to HD antigen and even a more pronounced response to HI antigen. Treatment of mice with 12 mg/kg CDDP resulted in immunosuppression. Thymus, lymph nodes, and spleen of animals treated with the higher dose of CDDP showed a marked cell depletion from both T and B areas, confirming that the immunosuppression was due to an indiscriminate elimination of both T and B lymphocytes. The immunosuppression and the cell depletion from lymphoid organs were more pronounced in younger mice. Thus, the effects of CDDP on the lymphoid organs and the immune response depend both on the age of the animals and on the dose of the drug. CDDP given in small doses enhances the PFC response, whereas a reduced PFC response is obtained following high-dose treatment.

Animals↗
PubMed1985

In vitro cloning of tumor stem cells in semi-solid media containing agar and agarose.

The formation of tumor stem cell colonies in vitro has been studied by comparing the growth of three mouse teratocarcinoma derived cell lines and one human teratocarcinoma derived cell line in semi-solid media containing either agar or agarose. We show that agaroses should be used in higher concentrations than agar to obtain comparable results. The maximum number of colonies were obtained in agarose over a broader range of concentrations (1%-4% for SeaPrep and 0.5%-2% for SeaPlaque agarose) than in agar, which allowed anchorage-independent growth of tumor cells only over a narrow concentration range (0.3%-0.5%). Overall, the preparation of media containing agarose was less cumbersome than preparation of agar-containing media, primarily because agaroses gelled more slowly and remained liquid in the physiological temperature range. Furthermore, the transfer of colonies from semi-solid media containing agarose to solid surface tissue culture dishes was much more efficient than the transfer of colonies from agar. The stock solutions of SeaPrep agarose could be kept ready for use for extended periods of time. All these features show that the low melting point agarose has considerable advantages over agar for preparation of semi-solid media for anchorage-independent tumor cell growth.

Agar↗
PubMed1985

Lymphocyte function in experimental endemic syphilis of Syrian hamsters.

We have studied the changes in the lymph nodes, spleen and thymus that occur in inbred LSH Syrian hamsters infected with Treponema pallidum Bosnia A, the causative agent of endemic syphilis, as well as the B-cell responses of these infected animals to helper T-cell independent and dependent antigens. The lymph nodes increased significantly in weight up to 6 weeks after infection, and contained viable treponemes. No significant changes in the spleen weight were observed, and no viable treponemes could be recovered from the spleen. However, the size of the thymus decreased steadily during the course of the disease. The relative number of Ig+ cells (B cells) increased in the spleen and regional lymph nodes, whereas the relative number of T cells decreased during the course of infection. In both the spleen and lymph nodes, the relative number of macrophages increased initially and decreased thereafter in the form of a bell-shaped curve showing a peak at 4-6 weeks of infection. The ability of splenic lymphocytes from infected hamsters to mount a primary PFC response to pneumococcal polysaccharide type III (SIII), a helper T-cell independent antigen, was elevated throughout the course of infection. However, the splenic PFC response to sheep erythrocytes (SRBC), a helper T-cell dependent antigen, was increased only during the first 4 weeks of infection and progressively decreased thereafter. The PFC responses of infected lymph node lymphocytes to both SIII and SRBC were increased during the first 4 weeks and decreased thereafter. These data suggested that atrophy of the thymus seen in syphilitic infection is accompanied by the complex losses of subsets of T cells and altered B-cell functions. An early loss of suppressor T cells in both the lymph nodes and spleen occurs concomitantly with a loss of T helper cells and heterologous (treponema-unrelated) B-cell functions in the lymph nodes. Helper T cells are lost from the spleen only in the later stages of infection, whereas splenic B-cell functions remain intact throughout the course of the disease. These findings were further tested by in vitro methods where splenic and lymph node lymphocytes from infected hamsters were examined for their ability to respond to Con A in terms of the induction of antigen non-specific suppressor T cells. The mixing of Con A stimulated splenic or lymph node lymphocytes from infected hamsters was unable to inhibit the primary antibody responses of SRBC as compared to the normal control.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Latex bead technique for detection of the plaque-forming cell response to teratocarcinoma tumor antigens.

A latex bead technique modified for measuring the plaque-forming cell (PFC) response to teratocarcinoma tumor antigens in syngeneic animals is described. With this method one can detect both the primary (IgM) and the secondary (IgG) immune response to tumor antigens. Optimal detection of the PFC response depends on the proper ratio of sheep red blood cells to latex beads and the dose of tumor cell antigen used for immunization. The presence of fetal calf serum interfered with immunization of animals and the coating of the latex beads with the tumor cell antigens. The plaques obtained in response to immunization with teratocarcinoma cell antigens varied in size, probably reflecting the complex immune response to more than one class of antigens on tumor cells.

Animals↗
PubMed1983

The effects of regional factors on the growth rate and the differentiation of mouse teratocarcinoma.

Murine embryonal carcinoma cells, the pluripotent stem cells of teratocarcinoma were injected simultaneously into caudal and cranial sites on the back of syngeneic recipients in order to determine whether regional anatomical differences affect their take and growth rate and differentiation. The overall tumour take rate was higher in caudal than cranial sites, but the initial weight of tumours was higher in the cranial than caudal sites. Tumours developing in the two anatomical sites grew at the same rate with a linear increase in volume. At the end of the 4-week experimental period the differences in the size of anterior and posterior tumours were negligible and no histological differences were noted between the two groups. Our data indicate that regional factors significantly affect the take rate and the initial growth of this murine teratocarcinoma, i.e. the establishment of solid tumours from injected stem cells. The growth rate of established tumours was not affected by regional factors.

Animals↗
PubMed1982

Embryo-derived teratocarcinoma. IV. The role of immune factors in the regulation of teratocarcinogenesis.

Seven-day-old mouse embryos were transplanted under the kidney capsule of adult syngeneic recipients which were either X-irradiated, treated with cyclophosphamide, splenectomized or immunized with teratocarcinoma cell lines prior to embryonic transplantation. The yield of malignant tumors was decreased in preirradiated, as well as in cyclophosphamide-pretreated animals, as compared with untreated hosts. The effect of the pretreatment could be fully abrogated by allowing animals to spontaneously recover for 4 weeks or by adoptive transfer of thymus cells from untreated animals. Partial recovery was obtained by the adoptive transfer of spleen cells. Splenectomy at the time of embryonic transplantation did not affect the embryo-derived teratocarcinogenesis in C3H mice but reduced the yield of malignancy and the weight of tumors produced in C57BL/6 mice. Immunization of hosts with teratocarcinoma cells did not influence the subsequent embryo-derived teratocarcinogenesis. These data indicate that embryo-derived teratocarcinogenesis is regulated by X-ray and cyclophosphamide-sensitive cells residing in the thymus and the spleen. The permissiveness to teratocarcinogenesis seems to be a function of the total number of these regulatory cells in the host.

Animals↗
PubMed1982

Detection of plaque-forming cells by a latex bead technique.

A new latex bead technique for measuring the plaque-forming cell (PFC) responses to bacterial antigens is described. This technique has been designed for the study of antigens that cannot be readily coated onto SRBC but may also used for antigens that adsorb onto SRBC as well. Application of the latex based technique for the study of PFC response of hamsters to Treponema reiter antigen is described in detail. Using SIII, an antigen that readily adsorbs to SRBC, we have compared the latex bead technique and the conventional SRBC-PFC technique and found that the latex bead technique is more sensitive than the conventional technique. The technique can be used for direct and indirect PFC assays. Technical details for the optimal performance of the latex bead PFC assay are outlined.

Adsorption↗
PubMed1982

Ability of macrophages to process and present Treponema pallidum Bosnia A strain antigens in experimental syphilis of syrian hamsters.

The ability of macrophages to process and present treponemal antigens to T-lymphocytes was studied in early stages of experimental syphilis produced by Treponema pallidum Bosnia A strain (the causative agent of endemic syphilis) infection of inbred Syrian hamsters (LSH/Ss Lak strain). A difference was noticed in the response of macrophages obtained from the peritoneal cavity, lymph nodes, and spleens of the infected animals. In all of these locations, a general increase in the population of Ia(k)-positive macrophage was seen during the entire period of infection, i.e., 3 to 18 weeks after inoculation. Peritoneal cavity-derived macrophages showed no difference in antigen presentation to sensitized and nonsensitized T-lymphocytes for the first 7 weeks of infection. However, at 18 weeks after infection, peritoneal macrophages lost their ability to process treponema antigens. Spleen- and lymph node-derived macrophages did not exhibit a parallel loss in their ability to process treponema antigens. A fluctuation without a consistent pattern was noticed in the antigen processing and presentation by macrophages from the spleen and lymph nodes. In general, the sensitized T-lymphocytes responded to treponema antigen presented by macrophages more vigorously than the nonsensitized T-lymphocytes. An increased ability of spleen-derived macrophages to process and present antigens was noticed throughout the entire period of infection. The macrophages from the lymph nodes showed such an increase only temporarily at 3 weeks after infection. These data suggest that the processing and presentation of treponema antigens by macrophages in acute syphilitic infection fluctuates considerably and depends on the source of macrophages and the duration of the infection. The differences in the response of peritoneal cavity-, spleen-, and lymph node-derived macrophages probably reflect the complex interactions between the macrophage and other cells involved in the immune response to treponema infection.

Animals↗
PubMed1981

Evidence for depletion of Ia+ macrophages and associated immunosuppression in African trypanosomiasis.

The percentage of Ia antigen-bearing (Ia+) macrophages was significantly lower in mice infected with Trypanosoma rhodesiense than in normal controls. The degree of difference varied with the source of macrophages and time course of infection. The percentage of Ia+ macrophages isolated from spleens 10 days after infection was 71% of that in the controls, and depletion continued until Ia+ macrophages were almost undetectable 30 days after infection. The rate of depletion was slower in the peritoneal cavity. In contrast, Ia+ macrophages were not significantly depleted from the lymph nodes until 30 days after infection. The ability of macrophages from trypanosome-infected mice to present listerial antigen to sensitized T cells was significantly lower than in controls. Immune T cells had significantly less ability (43% of controls) to incorporate thymidine when exposed to splenic macrophages from infected mice during the early stage of disease. This loss of antigen presentation increased during the course of infection. Peritoneal macrophages also exhibited an early loss of ability to present antigen, but no significant decline occurred thereafter. No significant loss of antigen had occurred in the lymph node macrophages 10 days after infection, but during the later stages of the disease a significant loss was detected. Treatment of macrophages from infected and control mice with anti-Iab serum and complement inhibited their ability to present antigen. Our results demonstrate that Ia+ macrophages and their distribution can influence the ability of infected animals to process antigens and may therefore account in part for the immunosuppression observed in trypanosomiasis.

Animals↗
PubMed1980

Endemic syphilis: transfer of resistance to Treponema pallidum strain Bosnia A in hamsters with a cell suspension enriched in thymus-derived cells.

Direct evidence for involvement of thymus-derived (T) cells in host defense against syphilitic infection is presented. Irradiated, bone marrow-reconstituted hamsters receiving cells from hamsters immune to infection with Treponema pallidum strain Bosnia A had significantly lower weights and fewer treponemes per lymph node than animals that had received normal lymphoid cells or only normal bone marrow cells. Cell suspensions enriched in T cells from immune hamsters were obtained by sequential filtration of pooled spleen and lymph node cells through glass- and nylon-wool columns. The fractionated suspensions of cells responded poorly to stimulation by phytohemagglutinin, Escherichia coli lipopolysaccharide, and dextran sulfate, but responded relatively strongly to the T-cell mitogen, convanavalin A. After fractionation the proportion of cells susceptible to antithymocyte serum and complement increased significantly. These immune cell suspensions depleted of bone marrow-derived cells closely resembled unfractionated suspensions in their ability to confer resistance to challenge with T. pallidium.

Animals↗
PubMed1980

LSH hamster model of syphilitic infection.

The inbred LSH/Se LAK strain of hamster can be infected with Treponema pallidum Bosnia A, the causative agent of endemic syphilis. When infected, this strain consistently produced extensive chronic skin lesions that persisted for 6 to 9 months, even in the presence of peak antitreponemal antibody titers. The lymph nodes increased in weight and contained measurable numbers of treponemes. This infection also gave the hamster cross-immunity to T. pallidum Nichols and Treponema pertenue, the causative agents of venereal syphilis and frambesia, respectively. LSH hamsters are thus an excellent model to study the immune response mechanisms to syphilitic infection.

Animals↗
PubMedDate not supplied

A potential vaccine for cocaine abuse prophylaxis.

Presently, there are estimated to be 1.5 to 2.0 million individuals infected with HIV-1 in the U.S. and about 12 million worldwide. In the U.S. over 90% of reported cases of AIDS occurred among two subgroups, homosexual males and intravenous substance abusers (IVSAs). Currently, there is no anti-cocaine addiction medication available. In order to explore vaccination as an alternative means for protection against cocaine addition, we immunized inbred male Fisher rats with either cocaine emulsification in complete Freund adjuvant (CFA) or with cocaine conjugated with keyhole limpet hemocyanin (KLH), as carrier plus CFA. Animals were initially immunized with 0.1 mg/animal of cocaine or cocaine-KLH. Animals were given a booster with the corresponding agents after 4 weeks. Ten animals/group were used. Controls received normal saline at the time of immunizations. These animals were injected, intraperitoneally, with 25 mg/kg of cocaine, and were examined for the analgesic effect of cocaine by the hot plate method. The average analgesic effect of cocaine was significantly reduced (p greater than 0.03) in animals immunized with cocaine-KLH (13.77 s) as compared to saline controls (21.6 s). Fifty percent of the animals (5/10) in the cocaine-KLH group and 33% of the animals (3/9) in the cocaine immunized group appeared completely resistant to the effect of cocaine on the central nervous system (CNS). We also have determined the levels of cocaine-specific antibodies produced by each animal by an ELISA method. Degree of protection from cocaine seems to correlate well with the amount of anti-cocaine antibodies produced by each animal (-0.61).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Human studies on alcohol and susceptibility to HIV infection.

Here we review existing evidence that alcohol intake may influence the susceptibility to human immunodeficiency virus type 1 (HIV-1) infection and the effect that alcohol may have on accelerating the onset of AIDS after the initial infection. Possible immunological and psychosocial mechanisms to explain the increased incidence of HIV-1 infection in alcoholism are discussed.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Potential of the in situ polymerase chain reaction in diagnostic cytology.

Routine examination of cytologic material by light microscopy in our laboratory includes special stains and enzyme histochemistry, but molecular biology techniques are not generally employed. We examined the feasibility of utilizing the in situ polymerase chain reaction (PCR) for examination of archival cytologic specimens. Protocols were shortened in an effort to employ a technique that would be economical and have diagnostic relevance; a result would be obtained within two days of a request. Cases of transitional cell carcinoma were examined for the p53 tumor suppressor oncogene; preparation of direct incorporation PCR required eight hours of laboratory work, thermal cycling was performed overnight, and product visualization required three hours of laboratory work the following day. Amplification products were found in the cytoplasm and nuclear regions with an antidigoxigenin fluorescent and peroxidase probe. In situ PCR has enormous potential in the diagnostic cytology laboratory.

Base Sequence↗