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Biomedical subjects

R N Shen

Publications and source records attributed to R N Shen.

At least 19 recordsLinked to original sources
PubMed2000

[Enzymatic resolution of racemic naproxen in a low aqueous-organic biphase system].

A stereoselective hydrolysis of the racemic naproxen methyl ester by immobilized lipase from Candida rugosa in a low aqueous-organic biphase system was studied. Support polar, water content, the logP value of organic phase and product inhibition effected the activity of immobilized enzyme. According to these reaction conditions, a low aqueous-organic biphase system for the continuous production of (S)-(+)-Naproxen was developed. The reaction was carried out in a continuous-flow closed-loop 50 mL stirred bioreactor packed with YWG-C6H5, a poorly polar synthetic support on which the lipase had been immobilized by adsorption. The aqueous phase was permanently remained in the reactor associated with the immobilized enzyme particles; the organic phase containing substrate was pumped through this reactor and emerged with the products. The continous-flow stirred bioreactor containing 75 mg lipase was allowed to operate continuously for 60 days at 30 degrees C with a 25% loss of activity, 900 mg of (S)-(+)-Naproxen (eep 95%) were producted.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Stem cells from bone marrow, umbilical cord blood and peripheral blood for clinical application: current status and future application.

Bone marrow transplantation (BMT) has progressed rapidly during the past two decades to that of a treatment of choice as a therapeutically effective modality for the treatment of selected patients with malignant disease and non-malignant hematological disorders. However, its use is limited by availability of human leukocyte antigens (HLA)-matched donor cells, engraftment and graft-versus-host disease (GVHD). Prevention of GVHD, improvement in the speed and quality of marrow reconstitution, and screening of new immunomodulating agents which improve engraftment and augment hemopoiesis are intense areas of investigation. To this end there has clearly been progress in purification and characterization of human stem cells from different tissue sources. Discussed in this review are: (a) stem cell purification, characterization and ex vivo expansion; (b) bone marrow stem cell transplantation; (c) cord blood stem cell transplantation; (d) peripheral blood stem cell transplantation; (e) fetal liver stem cell transplantation; (f) in utero stem cell transplantation; and (g) evaluation of the capacity of stem cells to serve as targets for gene therapy.

Blood Cells↗
PubMed1996

A comparison of referral patterns and characteristics of patients with first episode symptomatic genital HSV-1 and HSV-2 infections in Sheffield.

OBJECTIVE: To ascertain factors associated with HSV-1 and HSV-2 isolates in patients attending a genitourinary medicine clinic with symptomatic first episode genital herpes (FEGH). DESIGN: Retrospective study. SUBJECTS: A total of 606 females and 333 males presenting with culture positive FEGH between 1990-94. SETTING: Department of Genitourinary Medicine, Royal Hallamshire Hospital, Sheffield, UK. METHODS: Group comparison of referral patterns, demographic data, prior and concurrent episodes of STD, recent partner change. RESULTS: HSV-1 infected patients of either sex were more likely to be general practitioner (GP) referred, to be white, and less likely to have had preceding STD episodes. Recent sexual partner change had occurred significantly more often in HSV-2 infected females but there was no similar difference between HSV-1 and HSV-2 infected males. CONCLUSION: The relative HSV-1:HSV-2 isolate ratio in FEGH is influenced by the referral patterns. HSV-1 isolates predominate in patients presenting to GPs who refer the patients to GUM clinics for accurate diagnosis, counselling, follow up and screening for other STDs.

Adolescent↗
PubMed1996

Forced over-expression of the myeloid zinc finger gene MZF-1 inhibits apoptosis and promotes oncogenesis in interleukin-3-dependent FDCP.1 cells.

The myeloid zinc finger protein MZF-1 is important in hematopoiesis. Previous studies have found that reducing expression of MZF-1 inhibited G-CSF-driven human marrow colony formation assays. In this study we found that retrovirally overexpressing MZF-1 in IL-3-dependent FDCP.1 cells inhibited their apoptosis when IL-3 was withdrawn. The MZF-1-transduced FDCP.1 cells also formed tumors when injected into congenic mice, whereas control FDCP.1 cells did not.

Animals↗
PubMed1994

Influence of elevated temperature on natural killer cell activity, lymphokine-activated killer cell activity and lectin-dependent cytotoxicity of human umbilical cord blood and adult blood cells.

PURPOSE: To determine whether hyperthermia is to the benefit or detriment of host immune function, the effect of hyperthermia was evaluated on various functions of T-lymphocytes from human umbilical cord blood and compared to that of adult blood. METHODS AND MATERIALS: Nonadherent mononuclear cells from cord blood or adult blood were used as the effector cells. To generate lymphokine activated killer (LAK) cells, effector cells were kept in culture for 5 days in complete medium containing recombinant human interleukin-2. To activate effector cells to become cytotoxic, cells were kept in culture in complete medium containing Con A. Cytotoxicity was determined in a standard 4-h chromium release assay using K-562 human erythroleukemic cells (in the natural killer cell activity assay) or Daudi cells (in the LAK cell activity or Lectin dependent cytotoxicity assay) as targets. For heat effects, cells in complete medium were heated at the desired temperature in a water bath for 1 h. RESULTS: Lymphokine-activated killer cell activity, lectin-dependent cytotoxicity and T-cell proliferative capacity were not deficient in human cord blood. Cytotoxic activities of T-cells from adult blood as well as from cord blood can be enhanced at febrile range (< or = 40 degrees C), and were significantly decreased by exposure to 1 h at 42 degrees C. CONCLUSION: The febrile responses (< or = 40 degrees C) to infection, in the course of malignant disease and with biological response modifiers treatment, may all be related to host defense mechanisms. Based on these observations, whole body hyperthermia (< or = 40 degrees C), in combination with the appropriate cytokines, may have therapeutic potential in the treatment of neonatal infections and malignancies under certain circumstances. Hyperthermia in febrile range may, therefore, confer an important immunoregulatory advantage to the host. In contrast, tumor killing therapeutic temperature (> 42 degrees C) which inhibits host immunocompetence should probably be used only for local hyperthermia.

Adult↗
PubMed1994

Comparative analysis of retroviral-mediated gene transduction into CD34+ cord blood hematopoietic progenitors in the presence and absence of growth factors.

Hematopoietic stem and progenitor cells present in umbilical cord blood at the birth of a child are efficiently transduced ex vivo by genes using retroviral vectors in combination with exposure of these cells to combinations of growth factors. Because retroviral-mediated gene transduction of adult bone marrow and blood hematopoietic stem and progenitor cells is greatly enhanced by growth factors, we evaluated the possibility that cord blood progenitors, which have extensive proliferative and replating capacity, could be efficiently transduced with a TK neo gene in a retroviral vector in the absence of growth factors, and also determined the influence of exogenously added growth factors on this transduction. Highly purified CD34+ (62% pure) cord blood cells isolated by magnetic bead separation were cultured in suspension for 72 hours with viral supernatant in the absence and presence of interleukin-3 (IL-3), IL-6, and steel factor. Evaluation of progenitor cell-derived colonies and polymerase chain reaction (PCR)/Southern analysis of the TK neo gene in resultant colony cells demonstrated that some gene transduction was apparent in the absence of growth factors (12.8-14.3% by PCR), but that this was greatly enhanced (40.0-44.4%) by addition of growth factors. Reverse transcription PCR analysis of the expression of IL-3, IL-6, and granulocyte-macrophage colony-stimulating factor genes in this population of cells suggested that the transduction, although at a lower efficiency, in the absence of added growth factors might in part be due to "constitutive" and viral supernatant-induced expression of these cytokine genes in the CD34(+)-enriched cell population.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, CD↗
PubMed1993

Enrichment, characterization, and responsiveness of single primitive CD34 human umbilical cord blood hematopoietic progenitors with high proliferative and replating potential.

To characterize the growth of cord blood progenitor cells, single nonadherent, low-density, T-lymphocyte-depleted CD34 cells were sorted by flow cytometer with an autoclone device into single wells containing culture medium and cytokines. These cells were evaluated for proliferation and for replating ability of their progeny. This latter effect is used as a measure of self-renewal capacity. Colony formation was assessed in 1 degree wells containing various cytokines, alone and in combination, and single colonies deriving after 21 days in semisolid medium were replated into 2 degree wells in the presence of the combination of purified preparations of recombinant human steel factor (SF, a c-kit ligand), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), interleukin-3 (IL-3), and erythropoietin (Epo). Replating of single colonies was performed also for 3 degrees, 4 degrees, and 5 degrees cultures. In the presence of serum, colony formation was observed in > 66% of the wells stimulated with the combination of Epo, SF, GM-CSF, G-CSF, and IL-3, and more than 39% of the colonies formed in these 1 degree wells were very large in size (> 2.5 mm in diameter, dense in the center, and containing > 10(4) cells/colony). The replating efficiency of these large colonies was up to 93% with generation of subsequent colonies of very large size. Replating could be shown for up to five generations. The cells in these colonies were large, nonspecific esterase positive, and contained large amounts of cytoplasm with one or more nuclei containing several nucleoli per nucleus. Smaller colonies (1 to 2.5 mm in diameter and dense in the center) containing similar cells and making up an additional 14% of the colonies formed in 1 degree wells also showed extensive replating capacity, including generation of larger colonies. These colony-forming cells are likely similar to the murine macrophage high-proliferative potential colony-forming cells. The cells giving rise to these colonies are present in about eightfold higher frequency in cord blood than in adult bone marrow. These cells may at least in part be associated with the successful hematopoietic repopulating capacity of umbilical cord blood cells.

Antigens, CD↗
PubMed1993

Antitumor effect of interleukin 7 in combination with local hyperthermia in mice bearing B16a melanoma cells.

Interleukin (IL)-7 has been evaluated for its influence, alone or in combination with local hyperthermia (LH), on B16a melanoma-bearing mice. Six- to eight-week-old C57BL/6J male mice were inoculated s.c. with 5 x 10(5) tumor cells into the left hind limb. Mice were randomly divided into four groups, and treated s.c. with IL-7 (5 ng) or saline as control, twice a day for three weeks beginning eight days after tumor inoculation. LH, using hot water circulator at 43 +/- 0.2 degrees C for 30 min, was induced to the limb with tumor twice a week for two weeks. Size of the primary tumor was measured every other day for five weeks. Mice were sacrificed five weeks after tumor inoculation. The size of the primary tumor and the number of lung metastases were reduced in mice treated either with IL-7 or LH alone. As a control for IL-7, granulocyte colony stimulating factor (G-CSF) alone had no effect on primary tumor size or number of lung metastases. The greatest antitumor effect was observed in mice treated with IL-7 in combination with LH. Survival was prolonged significantly only in mice treated with IL-7 plus LH compared with that of mice treated with saline. Decreased natural killer (NK) cell activity, number of Thy1.2 cells, and ratio of L3T4+/Lyt2+ cells were associated with tumor growth. These parameters were restored in mice treated with IL-7 plus LH. Increases in levels of IL-1 alpha, IL-6, tumor necrosis factor (TNF alpha) and interferon (IFN gamma) were associated with an increase in the survival of tumor-bearing mice treated with IL-7 and/or LH. These results suggest that changes in T-cell, NK cell and cytokines such as IL-1 alpha, IL-6, TNF-alpha and IFN-gamma in response to IL7 and/or LH might account for prolonged survival of B16a melanoma-bearing mice and that IL-7 might be useful as a potential antitumor agent combined with other therapy in certain malignant solid tumors with metastases.

Animals↗
PubMed1993

Comparative effects of suppressive cytokines on isolated single CD34(3+) stem/progenitor cells from human bone marrow and umbilical cord blood plated with and without serum.

A number of cytokines have been implicated in the suppression of myeloid stem and progenitor cell proliferation. It has been suggested that some of these act directly on the stem/progenitors themselves, based on the effects of these cells, plated in culture at low seeding densities, on highly enriched populations. These studies, however, do not definitively rule out effects on accessory cells. To more rigorously evaluate direct-acting suppressive effects of cytokines, such cytokines were assessed for their effects on colony formation initiated by single bone marrow (BM) or umbilical cord blood (CB) CD34 cells sorted into single wells in the presence of a combination of growth-stimulating cytokines (erythropoietin [Epo], steel factor [SLF], granulocyte-macrophage colony-stimulating factor [GM-CSF], and interleukin-3 [IL-3]) and in the presence or absence of serum. Under these conditions, it was demonstrated that H-ferritin, transforming growth factor-beta 1 (TGF-beta 1), and members of the chemokine family (macrophage inflammatory protein-1 alpha [MIP-1 alpha], MIP-2 beta, platelet factor 4 [PF4], IL-8, and macrophage chemotactic and activating factor [MCAF]) had direct significant suppressive activities on single stem/progenitor cells from adult human BM in the presence or absence of serum. Single sorted CB cells were much less sensitive to inhibition by these cytokines. The reasons for this differential sensitivity are not known. Of possible relevance to this for cytokines, such as H-ferritin and the chemokines that have actions during S-phase of the cell cycle, CB progenitors were in slower cycle at initiation of culture than were BM progenitors.

Antigens, CD↗
PubMed1993

In vivo effects of purified recombinant human macrophage colony-stimulating factor in combination with local hyperthermia on tumor progression in B16a melanoma bearing mice.

Recombinant human (rhu) macrophage colony-stimulating factor (M-CSF) was evaluated, alone or in combination with local hyperthermia (LH), for their antitumor effects in mice inoculated with B16a melanoma cells. Several tumor related parameters and other hematopoietic and immunologic parameters were evaluated 5 weeks after subcutaneous (s.c.) inoculation of tumor cells into the right limbs of C57BL/6J male mice. RhuM-CSF was administered at 20 micrograms/injection, s.c., twice a day for 5 days/week for 2 weeks beginning 6 days after tumor cell inoculation and LH (43 +/- 0.2 degrees C) was given for 30 min twice/week for 2 weeks. Combined therapy prolonged survival of mice and caused significant inhibition of tumor growth, as measured by the volume or size of primary tumor, number and size of lung metastases, and chromatin fragment (CF) formation in tumor bearing mice, while treatment with M-CSF or LH alone had less or no effect. Combined therapy also resulted in increased numbers of splenic T-lymphocytes and the ratio of T-helper/suppressor cells, restoration of natural killer (NK) cell activity, increased numbers of peritoneal macrophages and their erythrophagocytosis capacity, and increased release or production of tumor necrosis factor (TNF)-alpha, but not interleukin (IL)-1 alpha or IL-6. These results add to previous evidence that M-CSF might be a relevant therapeutic agent in combination with other therapies in the treatment of certain malignant diseases.

Animals↗
PubMed1992

Influence of recombinant human interleukin (IL)-7 on disease progression in mice infected with Friend virus complex.

Recombinant human (rhu) IL-7 was evaluated for its influence on disease progression in mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC). DBA/2 mice were injected i.v. with FVC, and then treated s.c. with rhuIL-7. IL-7 significantly prolonged survival time and decreased spleen focus-forming virus (SFFV) levels, expression of SFFV mRNA and SFFV protein production in FVC-infected mice. IL-7 did not appear to directly inactivate SFFV. Although both splenic weight and cellularity in FVC-infected mice treated with IL-7 were higher than those of normal mice, they were respectively 58% and 66% lower than those of the untreated FVC-infected mice. NK-cell activity was substantially lower in FVC-infected mice than in normal mice, while IL-7 restored NK-cell activity to normal levels. IL-6 and IFN-gamma levels were markedly reduced in FVC-infected mice compared to normal mice, but treatment of FVC-infected mice with IL-7 restored these cytokine levels. While the actual mechanisms of these effects are not yet known, the results suggest the potential therapeutic efficacy of IL-7 for certain hematopoietic and viral disorders, possibly mediated through an action on accessory cells and cytokine production.

Animals↗
PubMed1992

A reliable method for quantitating chromatin fragments by flow cytometry to predict the effect of total body irradiation and hyperthermia on mice.

The frequencies of chromatin fragments, including micronuclei, in murine thymus cells, spleen cells and bone marrow cells have been used as a quantitative indicator of gamma-ray induced chromosome damage and could be used to screen potential radioprotective agents as well. The yield of chromatin fragments induced in mice receiving different dosage levels of total body irradiation alone and in mice also given whole body hyperthermia as a potent radioprotector were assessed by flow cytometric analysis. Our results demonstrated that chromatin fragments induced by irradiation in vivo was clearly dose-dependent and that chromatin fragments could potentially serve as a biological indicator of radiation damage. One hour of whole body hyperthermia at 40 degrees C (+/- 0.2 degree C) given 20 hours before a lethal dosage (900 cGy) of total body irradiation protects 100% of DBA/2 mice from an LD 100/16 irradiation dose (dose of irradiation that killed 100% of the mice in 16 days). This is in good agreement with the percent of chromatin fragments formed in the cells of the protected animals, which showed no significant difference from those observed in the normal mice. The results indicate that whole body hyperthermia protected the thymus and bone marrow from irradiation damage. This study provides further evidence which supports that whole body hyperthermia can act as a potent radioprotector in vivo. Measurement of the frequencies of chromatin fragments by flow cytometry is simple and reliable. The method can be applied to screen radioprotective agents.

Animals↗
PubMed1991

Anti-tumor effects of recombinant human macrophage colony-stimulating factor, alone or in combination with local irradiation, in mice inoculated with Lewis lung carcinoma cells.

Recombinant human (rhu) macrophage colony-stimulating factor (M-CSF) was evaluated for efficacy, either alone or in combination with local X-irradiation (LR), in mice inoculated subcutaneously (s.c.) with Lewis lung carcinoma (LLC) cells. The size of the primary tumor and numbers of lung metastases, 21 days after tumor inoculation and 15 days after the start of treatment, were reduced by 87% in tumor-bearing mice treated with 20 micrograms/dose M-CSF s.c. twice a day for 5 days. LR (800 cGy) to the tumor once a week for 2 weeks had a moderate anti-tumor effect and enhanced the anti-tumor effect of M-CSF. Hematological parameters, including nucleated cellularity in peripheral blood, femoral marrow, spleen and peritoneal exudate, as well as marrow and splenic granulocyte-macrophage progenitor cells, and numbers of splenic Thy 1.2+ cell and peritoneal mast cells, were perturbed in LLC-bearing mice, and were influenced by treatment with M-CSF and LR. Treatment with M-CSF plus LR, but not with either agent alone, was associated with a significant, although slight, enhancement in survival time for LLC-bearing mice. Inability to obtain a better survival-enhancing effect appeared to be related to the limited treatment, since the anti-tumor effects of M-CSF were more notable early on in disease progression and were related to the dose of M-CSF used. The effects of M-CSF were most probably indirect ones on the host immune system. M-CSF, in combination with LR, may be of benefit in the treatment of human tumors that have metastatic potential.

Animals↗
PubMed1991

In vivo effects of recombinant human interleukin 6, alone or in combination with local irradiation, on tumor growth in Lewis lung carcinoma-bearing mice.

Lewis lung carcinoma (LLC)-bearing mice were used as a mouse model to evaluate effects of recombinant human (rh) interleukin (IL) 6 and local X-irradiation (LR) on the growth of primary tumors and lung metastases. Mice were inoculated s.c. with LLC tumor cells and then treated with rhIL-6 (100 ng/dose) s.c. twice a day (b.i.d.) for 5 days, beginning 6 days after tumor inoculation. LR (800 cGy) was administered to the site of the primary tumor 6 days after tumor inoculation and again 1 wk later. Mice were then observed for survival or sacrificed at day 21 after tumor inoculation to determine size of primary tumor, numbers and size of lung metastases, and other hematological parameters including numbers of granulocyte-macrophage progenitor cells (CFU-gm). The size of the primary tumor and numbers of lung metastases were reduced by rhIL-6. LR enhanced the antitumor effect of rhIL-6 significantly, while LR alone had only a slight antitumor effect. Tumor-associated increases in peripheral blood, femoral marrow, splenic-nucleated cellularity, and marrow and splenic CFU-gm were reduced in mice treated with rhIL-6 plus LR. Prolonged survival time was observed only in tumor-bearing mice treated with rhIL-6 in combination with LR. The antitumor effects in vivo of rhIL-6 appear to be mediated indirectly as rhIL-6 had no effect on proliferation of LLC cells in vitro as assessed by colony and 3H-thymidine incorporation assays. These studies suggest that rhIL-6 may have therapeutic value in the treatment of certain malignancies, especially if used in combination with LR.

Animals↗