PubMed Health⌕ Search

Biomedical subjects

J Epstein

Publications and source records attributed to J Epstein.

At least 19 recordsLinked to original sources
PubMed1992

Ouabain-resistant transfectants of the murine ouabain resistance gene contain mutations in the alpha-subunit of the Na,K-ATPase.

A 6.5-kilobase murine genomic DNA fragment isolated by Levenson et al. (Levenson, R., Racaniello, V., Albritton, L., and Housman, D. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 1489-1493) (called the ouabain resistance gene) has been shown to produce ouabain resistance in primate cells. Preliminary sequence information has revealed no homology with the coding sequence of the Na,K-ATPase. We have introduced this murine sequence into monkey and murine cells in an attempt to characterize its mechanism of action. In our experiments, transfection of this DNA fragment is associated with the low frequency (1 in 8 x 10(5) cells) appearance of ouabain-resistant clones of CV1, COS, and NIH 3T3 cells, an event not seen in control transfections. Characterization of a new clone of ouabain-resistant CV1 cells (called OR8 cells) revealed a 5-fold increase in the IC50 for ouabain inhibition of rubidium uptake and a 10-fold increase in cell survival on ouabain. Although the murine sequence was detectable in Southern blots of ouabain-resistant cells soon after transfection, this exogenous DNA was rapidly lost despite continued exposure to ouabain. Furthermore, we were unable to detect message expression by this genomic sequence in any of the three cell types tested. Instead, we found that all three ouabain-resistant cell lines exhibited point mutations in a domain of the alpha-subunit that has been implicated in ouabain sensitivity (H1-H2). One of these mutations (Asp121-Asn121 in OR8 cells) has been previously reported to cause ouabain resistance (Price, E.M., Rice, D.A., and Lingrel, J.B. (1989) J. Biol. Chem. 264, 21902-21906). Other novel mutations in the H2 transmembrane domain were also detected. We postulate that the "ouabain resistance gene" is important in the early selection process on ouabain but that the permanent ouabain-resistant phenotype is due to a stable mutation in one allele of the alpha-subunit of the Na,K-ATPase.

3T3 Cells↗
PubMed1992

Compliance with infection control procedures in a dental hospital clinic.

Dental hospital staff and students were observed during clinical work for their compliance with infection control procedures, as recommended by the British Dental Association. A total of 183 contacts between health care worker and patient were scrutinised during December 1990. Nearly all health care workers (96%) wore gloves to carry out dental treatment, but in some cases gloves were neither changed nor hands washed between patients. Only one half wore protective eyewear and about one third (38%) wore no mask. Some dental surgery assistants used heavy duty gloves and some even scrubbed dirty dental instruments without wearing any gloves. Strict audit is clearly needed in every clinical setting in order to ensure compliance with infection control.

Attitude of Health Personnel↗
PubMed1992

Interleukin-6 fused to a mutant form of Pseudomonas exotoxin kills malignant cells from patients with multiple myeloma.

IL-6-PE4E is a recombinant protein consisting of interleukin-6 (IL-6) fused to a mutant form of Pseudomonas exotoxin in which four basic amino acids are changed to glutamate (PE4E). The chimeric toxin has been previously shown to specifically kill malignant hepatic, prostatic, epidermoid, and myeloma cell lines in vitro. To explore the possible clinical utility of IL-6-PE4E, particularly as an agent for ex vivo purging of marrow for autologous bone marrow transplantation (ABMT), we tested malignant cells from patients with multiple myeloma for sensitivity to this chimeric toxin. Ficoll-purified bone marrow cells were incubated with and without IL-6-toxin for 2 to 3 days. Eight of the 15 myeloma patients had cells that were sensitive to IL-6-toxin as measured by a decrease in the level of protein synthesis. Cells from five patients were very sensitive to IL-6-PE4E, with 50% inhibition of protein synthesis (ID50) achieved at or below 6 ng/mL (7 x 10(-11) mol/L). Cells from three additional patients showed moderate sensitivity, with ID50s between 30 and 140 ng/mL. The remaining seven samples showed little or no sensitivity, with ID50s greater than or equal to 400 ng/mL. Normal bone marrow cells or normal BFU-E and CFU-GM were resistant to the IL-6-toxin even at 1,000 ng/mL. Neither IL-6, IL-2-PE4E, nor an enzymatically deficient mutant of IL-6-PE4E was cytotoxic toward the myeloma cells, indicating that the cytotoxic effect of IL-6-PE4E required the adenosine diphosphate-ribosylation function as well as the specific ligand. Our data suggest that IL-6-toxin could be effective in ex vivo marrow purging in selected multiple myeloma patients who are candidates for ABMT, and that this toxin should also be investigated further for in vivo therapy.

ADP Ribose Transferases↗
PubMed1992

Recombinant human mullerian inhibiting substance inhibits human ocular melanoma cell lines in vitro and in vivo.

Since Mullerian Inhibiting Substance (MIS) causes regression of the Mullerian duct, the anlagen of the uterus, vagina, and fallopian tube, we expected and have previously observed that purified recombinant human MIS causes regression of gynecological tumors. However, recent experiments indicating that neural crest derivatives might be responsive to MIS prompted study of a group of human ocular melanoma cell lines in 4 in vitro inhibition assays, and a subrenal capsule assay in vivo. Ocular melanoma cell lines that grew well in a respective assay were studied with MIS to determine whether this biological modifier could inhibit growth. Three human ocular melanomas, OM431 (P less than 0.01), OM467 (P less than 0.02), and OM482 (P less than 0.03), were growth-inhibited by highly purified human recombinant MIS in soft agarose. A dose-dependent tumor inhibition was noted when OM431 cells were incubated with MIS in a liquid colony inhibition assay (P less than 0.05). In addition, OM467 was inhibited (P less than 0.05) by MIS in a multicellular tumor spheroid assay. Cell cycle analysis indicated that OM431 cells were inhibited in monolayer by MIS while in G1. At 100-fold lower serum concentrations than required in the media of in vitro assays, MIS delivered via i.p. osmotic pumps inhibited (P less than 0.05) in vivo the growth of OM431 implanted beneath the renal capsule of nude and CD-1 irradiated mice when compared to mice given implants of pumps containing no MIS. The responsiveness of ocular melanoma to MIS broadens the spectrum of tumors that might be treated with MIS and suggests further investigation of other neural crest tumors.

Animals↗
PubMed1992

Myeloma phenotype: clues to disease origin and manifestation.

Phenotypic analysis of myeloma cells has had a major impact on our understanding of the development of the disease. Heterogeneity in the expression of lineage- and differentiation-associated antigens has helped delineate a circulating clonal premyeloma cell compartment coexpressing CD19 and CD11b. These cells can be stimulated in vitro to proliferate and differentiate into the mature myeloma cells. Other studies have demonstrated the involvement of very early bone marrow B lymphocytes, which could be differentiated into myeloma cells through a CD10-positive intermediate stage. These data suggest that myeloma originates in the bone marrow and is mobilized through the circulation to and from extramedullary sites, probably lymph nodes, which are required for their development. Subsequently, these cells return to the bone marrow or soft-tissue sites, using adhesion molecules for homing to sites that can provide the stimuli for expansion and maturation. Development of myeloma and disease manifestation are governed by a network of cytokines. Among the cytokines, IL-6 has been promoted as the major myeloma growth factor. Recent findings indicate that, whereas myeloma cells have the ability to express both the IL-6 and its receptor gene, their ability to respond to the cytokine is minimal. The requirement in vitro for both IL-3 and IL-6 for the stimulation of premyeloma cell proliferation and differentiation suggests a role for IL-6 in affecting differentiation of myeloma progenitors and the involvement of an earlier hematopoietic progenitor. Frequent association with myeloid dysplasia and neoplasia and expression of multiple hematopoietic lineage-associated markers forward the hypothesis that myeloma originates in a hematopoietic stem cell.

Cytokines↗
PubMed1991

[The evidence of human immunodeficiency virus infection in the seronegative subjects of high-risk groups].

BACKGROUND: Polymerase chain reaction (PCR) is a new diagnostic procedure which has been used to recognise HIV-infected individuals who remain seronegatives. METHODS: Genomic DNA isolated from the peripheral blood mononuclear cells of 90 high-risk individuals were analyzed by PCR using gag primers SK 38/39. Subjects were classified in four groups: 42 drug abusers, 35 heterosexual partners of HIV-infected individuals, 9 homosexual men, and 4 health care workers accidentally exposed to HIV. Liquid hybridization using radiolabelled probes was done to confirm the results. All samples were also tested for HIV antigen and antibodies (Ab) using EIA and Western blot (WB). RESULTS: Two out of 11 (18%) drug abusers and 5 out of 34 (14%) couples were PCR positive in absence of HIV antibodies. This silent HIV infections were not recognized in homosexuals and health care workers. All 38 seropositive samples were PCR positive. None of the samples PCR+/Ab- was positive for HIV antigenemia or showed indeterminate results in the WB assay. CONCLUSIONS: Silent HIV infections were recognized in drug abusers (18%) and couples of HIV-infected individuals (14%). Mechanisms involved in the production of this "occult" HIV infections are reviewed.

HIV Antibodies↗
PubMed1991

Viruses and chronic disorders involving the human oral mucosa.

Viruses have been implicated in the etiology of several chronic disorders of the oral mucosa. Most of these associations have been with DNA viruses, particularly certain herpesviruses, which are associated, for example, with some cases of erythema multiforme and with hairy leukoplakia. Papillomaviruses are associated with various papillomatous lesions, focal epithelial hyperplasia, and possibly with some carcinomas. Viruses may possibly be associated with recurrent aphthae, Behçet's syndrome, and some dermatoses. The literature concerning these possible associations is reviewed. However, much more research needs to be done before the full story of viral associations with oral mucosal disorders can be written.

Burkitt Lymphoma↗
PubMed1990

Markers of multiple hematopoietic-cell lineages in multiple myeloma.

Multiple myeloma is considered a cancer of mature plasma cells. Recent studies, however, suggest the possible involvement of early B cells and the expression of myelomonocytic antigens by myeloma cells. Using flow cytometry, we searched for evidence of the expression of genes specific for different hematopoietic lineages by tumor cells in bone marrow aspirates from 27 patients with aneuploid multiple myeloma. In addition to features characteristic of myeloma cells, we found evidence of the frequent expression by myeloma tumor cells of the pre-B-cell antigen CALLA (common acute lymphocytic leukemia antigen) (in specimens from 58 percent of patients) and of megakaryocytic (88 percent), myelomonocytic (65 percent), and erythroid (39 percent) surface markers. The proportion of tumor cells expressing the different markers varied among patients, from 2 to 100 percent of recognizable tumor cells. We conclude that cells of multiple lineages are involved in myeloma--a finding that is consistent with the hypothesis that there is a common primary neoplastic lesion for all hematologic cancers.

Aneuploidy↗