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Biomedical subjects

M Patchen

Publications and source records attributed to M Patchen.

7 recordsLinked to original sources
PubMed1998

Activation of rat macrophages by Betafectin PGG-glucan requires cross-linking of membrane receptors distinct from complement receptor three (CR3).

PGG-glucan (Betafectin) is a soluble, highly purified yeast (1,3)-beta-glucan with broad anti-infective and immunomodulatory activities. These studies evaluated the ability of PGG-glucan to directly elicit O2- and tumor necrosis factor alpha (TNF-alpha) production by rat leukocytes in vitro. Particulate beta-glucan stimulated O2- production by the rat NR8383 alveolar macrophage cell line and resident rat peritoneal macrophages, but soluble PGG-glucan did not. In contrast, presentation of PGG-glucan to cells after covalent immobilization to a plastic surface caused a direct stimulation of O2- and TNF-alpha production. The O2- response of rat leukocytes to immobilized PGG-glucan was inhibited by soluble PGG-glucan, indicating that cellular responses to both immobilized and soluble PGG-glucan occur via common cell surface receptors. Because complement receptor type three (CR3) has been proposed as a beta-glucan receptor on human leukocytes, NR8383 cells were evaluated for the presence of CR3. Indirect immunofluorescence and flow cytometric analysis showed that despite being responsive to both particulate and immobilized beta-glucans, NR8383 cells expressed no detectable CR3. These results indicate that the beta-glucan receptors on NR8383 cells are not CR3 and suggest that physical presentation plays an important role in inducing pro-inflammatory leukocyte responses to PGG-glucan.

Adjuvants, Immunologic↗
PubMed1997

Serum-free culture conditions for cells capable of producing long-term survival in lethally irradiated mice.

The goal of ex vivo culture is to expand and/or differentiate cells in culture such that they retain their functional characteristics when reinfused into a patient. The studies presented here analyzed the use of culture conditions devoid of serum to expand murine hematopoietic stem cells. Bone marrow cells from male B6D2F1/J mice were cultured for up to 28 days in serum-free medium in the absence or presence of stem cell factor (SCF), GM-CSF or a combination of the two factors. Cells cultured for up to 21 days were assessed for granulocyte-macrophage colony-forming cells (GM-CFC), spleen colony-forming units, and cells responsible for short-term and long-term hematopoietic repopulation in lethally irradiated mice. Compared to initial seeding levels, the presence of SCF and GM-CSF increased total cell numbers 90-fold and GM-CFC numbers 42-fold over a 21-28 day culture period. Although spleen colony-forming unit cells did not increase, they were maintained at initial seeding levels over a 21-day period in the presence of SCF and GM-CSF. In lethally irradiated mice, survival enhancement and hematologic reconstitution were optimum with cells cultured for only seven days: survival at six months was 100% with cells cultured in SCF plus GM-CSF or SCF alone, compared to 50% with cells cultured with only GM-CSF. Hybridization analysis of bone marrow, spleen and thymus DNA from irradiated mice transplanted with these cultured cells confirmed male donor cell-derived repopulation at 45 days and 180 days post-transplant. These studies illustrate that murine GM-CFC can be expanded and that long-term repopulating hematopoietic cells can, at the minimum, be maintained ex vivo in serum-free culture. The use of defined serum-free culture systems holds great promise for further evaluation of the mechanisms that control hematopoietic stem cell proliferation.

Animals↗
PubMed1994

Erythroid progenitor (BFU-E, CFU-E) proliferation as inferred from 5'bromodeoxyuridine labeling.

Survival patterns of burst-forming unit-erythroid (BFU-E) and cluster-forming unit-erythroid (CFU-E) were studied in B6D2F1 mice after 5'bromodeoxycytidine (BrdCyd) infusion and near-ultraviolet (near-UV) light treatment. Comparison of the kinetics of BrdCyd sensitization of these colony formers with the kinetics of granulocyte-monocyte colony-forming cells (GM-CFC) and colony-forming unit-spleen (CFU-S) demonstrated a similar, but distinguishable, pattern of labeling between BFU-E and CFU-S. BFU-E and CFU-S each contain a subpopulation of unlabeled cells that diminishes with a half-life of 35 to 40 hours. Subsequent comparisons of this close association of BFU-E and CFU-S in Sl/Sld mice, again, showed similar patterns of BrdCyd labeling without evidence of an unlabeled or G0 subpopulation. These results are discussed with respect to the likelihood of a precursor relationship between these two cell types.

Animals↗
PubMed1992

Effects of anti-CD3 monoclonal antibody on engraftment of T-cell-depleted bone marrow allografts in mice: host T-cell suppression, growth factors, and space.

To investigate the role of CD3-positive T cells in allogeneic marrow rejection in mice and to examine the effects of anti-CD3 monoclonal antibody (MoAb) on allogeneic marrow engraftment, a hamster MoAb, 145-2C11, with specificity for the CD3 epsilon portion of the murine T-cell receptor complex was administered to B6 (H-2b) mice that had been sublethally irradiated with 626 cGy and injected with 10 x 10(6) T-cell-depleted B6C3F1 (H-2b/k) bone marrow cells. Lymphoid chimerism status was assessed by flow cytometric analysis of peripheral blood lymphocytes using H-2k-specific MoAb 5 to 6 weeks after bone marrow transplantation. When hosts were treated with 400 micrograms of anti-CD3 MoAb at the time of marrow injection, the percentage of donor-type cells was 75.2% +/- 15.0%, while it was 1.9% +/- 1.2% in untreated mice. It was demonstrated that anti-CD3 MoAb not only suppressed T-cell function but also induced colony-stimulating factors in host mice, and that enhancement of marrow engraftment in anti-CD3 MoAb-treated mice was associated with factor release as well as suppression of host T-cell function. Results were consistent with engraftment being enhanced by a differential response of donor (rather than host) marrow to serum factors in association with host T-cell immunocompromise.

Animals↗
PubMed1987

16,16-Dimethyl prostaglandin E2 increases survival in mice following irradiation.

16,16-Dimethyl prostaglandin E2 (DiPGE2), a stable analog of PGE2, increases the LD50/30 survival in CD2F1 male mice when given prior to ionizing radiation. Subcutaneous administration of 40 micrograms of DiPGE2 30 min prior to 60Co gamma irradiation extends the LD50/30 from 9.39 Gy in the control animals to 16.14 Gy in DiPGE2 treated, with a dose reduction factor of 1.72 [95% confidence limits: 1.62, 1.82]. The degree of protection is dependent on both the time of administration and the dose of the prostaglandin. Ten micrograms administered 5 min prior to receiving a lethal dose of 10 Gy provides 90% survival but only 10% survival if administered 30 min prior to irradiation. Experiments to determine the in vivo concentration of DiPGE2 in organs postinjection show increased levels over time, but these are not correlated with protection. At 30 min after injection, as much as 80% of the DiPGE2 present in the spleen and plasma is unmetabolized. These results suggest that the protection results from the physiologic action of DiPGE2 rather than direct in vivo detoxification of radicals.

Animals↗
PubMed1981

Differential killing efficacy of twenty antitumor drugs on proliferating and nonproliferating human tumor cells.

The lethal effects of a 1-hr treatment with 20 antitumor drugs on proliferating and nonproliferating cultured human colon carcinoma cells (line LoVo) were analyzed quantitatively by the colony-forming technique. Proliferating cells were obtained from exponentially growing cultures, while nonproliferating cells were from cultures in a stationary phase of growth. The 1-hr treatment was intended to approximate serum peak levels after bolus administration. Two agents, cis-platinum and vindesine, were more effective on nonproliferating than on proliferating cells. Mitomycin C, nitrosourea, and dihydroxybisalkylanthracenedione were equally effective on proliferating and nonproliferating cells. The low lethal activity (less than 1 log) of methylglyoxal bis(guanylhydrazone), hycanthone, and vinblastine was similar in proliferating and nonproliferating cells. For most drugs (Adriamycin, rubidazone, bleomycin, maytansine, vincristine, epipodophyllotoxin, fluorouracil, hydroxyurea, methotrexate, and transplantinum) cytotoxicity was significantly less pronounced (or even totally absent) in nonproliferating than in proliferating cells. These results demonstrate the significance of cellular proliferation kinetics in determining sensitivity to antitumor therapy. Nonproliferating human cells have decreased sensitivity to most antitumor agents. An occasional agent may present increased activity to nonproliferating cells; but at best, few agents can be expected to be as effective on nonproliferating as on proliferating cells.

Animals↗