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Biomedical subjects

W D Mercer

Publications and source records attributed to W D Mercer.

11 recordsLinked to original sources
PubMed1996

Characterization of a proteinaceous antimicrobial produced by Lactobacillus helveticus CNRZ450.

An antimicrobial substance which resembles a bacteriocin was identified in culture supernatant fluids of Lactobacillus helveticus strain CNRZ450. The bacteriocin was active against a narrow range of strains from closely related species of homofermentative lactobacilli. Its mode of action appeared to be bacteriostatic. Partial purification of the bacteriocin suggested that it was a complex protein with a mol. wt of between 30 and 50 kDa, although there is some evidence that the polypeptide monomer has a mol. wt of around 17 kDa. There was no evidence indicating an extrachromosomal location for its genetic determinant. PCR generated an amplicon from total DNA from strain CNRZ450 using primers based on the helJ gene sequence. A fragment showing homology to this amplicon was located in an EcoRI digest of total DNA from strain CNRZ450. The pattern obtained was different from that obtained with the helveticin J producer strain NCFB481. It is possible, therefore, that the antimicrobial from strain CNRZ450 is related to helveticin J at the DNA sequence level although the physical properties of the two antimicrobials reveal several differences.

Bacteriocins↗
PubMed1989

Natural killer cell activity and lymphocyte subsets in parenteral heroin abusers and long-term methadone maintenance patients.

We studied natural killer (NK) activity and lymphocyte subsets in 11 active parenteral heroin abusers, 11 long-term methadone-maintained former heroin abusers and 11 apparently healthy individuals. All subjects were males aged 23 to 49 and none had active infectious or inflammatory diseases. All current or former heroin abusers were seronegative for antibody to human immunodeficiency virus. The methadone maintenance patients were socially rehabilitated and had not abused drugs parenterally for at least 10 years. NK activity was determined by a standard Cr-release cytotoxicity assay using K562 cells as targets, and lymphocyte subsets were determined by direct immunofluorescence using flow cytometry. At all three effector-target ratios (100:1, 50:1 and 25:1), NK activity was reduced significantly (P less than .01) in parenteral heroin abusers compared with methadone maintenance patients and apparently healthy individuals. The latter two groups did not differ from each other. Parenteral heroin abusers also had higher absolute numbers of CD2, CD3, CD4 and CD8-positive cells. These data support our hypothesis that significant abnormalities of cellular immunity in parenteral heroin abusers can be normalized by successful long-term methadone treatment.

Adult↗
PubMed1986

Light chain myeloma with meningeal and pleural involvement.

A 76-year-old woman with newly diagnosed lambda light chain myeloma was found to have involvement of the pleura and meninges. Direct immunofluorescence demonstrated the monoclonal nature of plasma cells found in the pleural fluid; morphologically similar cells were found in the cerebrospinal fluid and bone marrow. Immunoelectrophoresis revealed lambda light chains in the pleural fluid and cerebrospinal fluid, as well as in the serum and urine. Clinically apparent pleural involvement and meningeal involvement by myeloma are each rare events. This is believed to be the first report of both phenomena occurring simultaneously and the first known case of light chain myeloma involving the cerebrospinal fluid.

Aged↗
PubMed1981

Failure of estradiol immunofluorescence in MCF-7 breast cancer cells to detect estrogen receptors.

An indirect immunofluorescence assay was used to detect estradiol in MCF-7 breast cancer cells to determine if the estradiol-specific fluorescence observed represented estrogen receptor-bound estradiol. Appropriate controls were used to demonstrate the immunological specificity of our assay procedures. Initial studies of estradiol binding in MCF-7 cells were performed at 20 degrees for 1 hr with different concentrations of estradiol. Cytoplasmic and nuclear staining were observed following treatment with 10 nM estradiol, but not with lower concentrations which were nevertheless still sufficient to saturate estrogen receptor. The staining intensity increased with higher estradiol concentration, which is consistent with estradiol binding to lower-affinity binding sites. In order to further determine if estradiol binding by estrogen receptor was being detected, we pretreated MCF-7 cells with 5 nM diethylstilbestrol at 37 degrees for 1 hr to translocate all estrogen receptor to the nucleus and then administered estradiol at varying concentrations for 4 hr at 4 degrees. The estradiol was still primarily detected in the cytoplasm, although virtually all of the estrogen receptor was found to be present in the nucleus by standard [3H]estradiol binding assays. Additional immunochemical studies using sucrose gradient analysis to detect antibody-estradiol-receptor complexes clearly established that these complexes could not be detected. The present results suggest that, although immunocytochemical assays can specifically detect estradiol in MCF-7 cells, the estradiol is bound to lower-affinity binding sites rather than to estrogen receptor. Saturation analyses of intact viable MCF-7 cells performed at 37 degrees for 30 min using [3H]estradiol at concentrations ranging from 0.1 to 93 nM revealed an additional lower-affinity estradiol-binding site besides the receptor, perhaps analogous to the Type II sites reported in the rat uterus and human breast cancers.

Binding Sites↗
PubMed1980

The use of immunocytochemical techniques for the detection of steroid hormones in breast cancer cells.

Indirect immunofluorescence and immunoperoxidase assays were developed to detect estradiol and progesterone in breast cancer cells. Appropriate controls were used to confirm immunologic specificity. Studies of estradiol binding by human breast cancer cells identified three groups: no detectable binding (25%); all tumor cells exhibiting binding although to different degrees (4%); and tumors with varying numbers of positive and negative cells (71%). Similar observations were made with respect to progesterone binding. The percentage of cells with estradiol binding was correlated with the amount of estrogen receptors (ER) present in the tumor specimens. Post-hormone binding events e.g., nuclear binding of estradiol, were also evaluated. Some tumor cells showing cytoplasmic binding of estradiol did not show nuclear binding of estradiol; such tumors lacked detectable diethylstilbestrol under routine assay conditions, and relatively high concentrations of estradiol were needed to observe estradiol-specific staining. The results suggest that the immunocytochemical assays detect hormone-specific binding, but that the binding is probably due to multiple classes of steroid-binding sites.

Animals↗
PubMed1980

Are histochemical methods for estrogen receptor valid?

Because of the great usefulness of estrogen receptor determinations in selecting therapy for breast cancer patients a number of histochemical and immunohistochemical methods for visualizing bound estrogen in cells and tissue sections have been proposed. We discuss all of these histochemical methods in the light of the known properties of the estrogen receptor and other estrogen binders, and we consider some criteria that must be met if such methods are to be considered valid for receptor. In spite of the great potential value of histochemical methods, we are forced to conclude that, in their present form, none of them are likely as yet to be detecting estrogen receptor.

Breast Neoplasms↗