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Biomedical subjects

W M Mitchell

Publications and source records attributed to W M Mitchell.

At least 73 records · Page 4Linked to original sources
PubMed1986

Effects of the mobilization of aged tissue cadmium by chelating agents.

An examination of the kidney and liver subsequent to the mobilization of aged cadmium deposits from them by the use of both dithiocarbamates and 1,2-dimercapto-1-propranolol (BAL) was carried out. No striking permanent effects due to cadmium mobilization were noted in the kidneys or livers for most of the chelating agents used. After the mobilization of part of the cadmium burden, the remaining cadmium gives evidence of undergoing a redistribution, leading to a renewed increase in both the kidney and liver levels of this element.

Animals↗
PubMed1986

Inhibition of murine interferon production following in vivo administration of benzo[a]pyrene.

To investigate whether alteration in interferon (IFN) production might serve as a biomarker for certain toxic chemical exposures, an in vivo mouse model system was studied. Female C3H mice were injected intraperitoneally with varying doses of benzo[a]pyrene (BP), and at various times subsequent to this treatment, serum IFN levels, following Sendai virus induction, were determined by a cytopathic effect inhibition assay. Doses of 4.6 mg/mouse (180 mg/kg body weight) caused a significant depression in IFN production at 12, 48, and 120 h after BP administration. Doses of 0.46 mg also produced significant decreases at 48 h following exposure. At 48 h post-BP treatment, the reduction in serum IFN titers in treated animals relative to controls was: 62% for the 0.46-mg dose, and 94% for the 4.6-mg dose. These results indicate that systemic administration of BP can significantly depress the whole-animal IFN response to viral stimulation, and that such depression can persist for a rather extended period at certain dose levels.

Analysis of Variance↗
PubMed1985

Mutagenic and cell transformation activities of representative phosphorothioate esters in vitro.

Five alkyl and five aryl phosphorothioates are ranked relative to parathion in effectiveness as base-pair mutagens in the Ames mutagenic assay. Three in each series were mutagenic. Two commercial insecticidal phosphates, included for comparison, were mutagenic. The mutagenic phosphorothioates contained a strong electron-withdrawing and/or a good leaving group, together with two other groups small enough to permit nucleophilic attack by a biomacromolecule on the electrophilic phosphorus atom. All but one of the phosphorothioates [i.e., O,O,O-tris(2,2,2-trifluoro)ethyl phosphorothioate, VI] required metabolic activation for mutagenicity to be manifested; hence most of the phosphorothioates per se evidently are not ordinarily sufficiently electrophilic to be mutagenic but must instead be transformed to more electrophilic oxygen-containing products. In evaluation for cell-transformation properties, methyl parathion was inactive, in contrast to VI. The phosphorothioates that were novel were synthesized by formation of the phosphite from the appropriate alcohol or phenol, followed by reaction of the phosphite with sulfur.

Animals↗
PubMed1985

Application of an objective biological assay of human interferons to clinical specimens and a survey of a normal population.

A rapid, quantitative, and nonsubjective method of interferon assay is described, which can be readily applied to clinical specimens. Automated data acquisition and data reduction allowed a significant increase in volume per unit of time over existing methodologies. Plasma always yielded higher (usually 2:1) interferon values than did serum obtained simultaneously. Ranges of interferon levels in plasma in normal control populations are reported as well as ranges for clinical virology laboratory technicians and patients with terminal malignancies or collagen vascular diseases.

Biological Assay↗
PubMed1985

Antidotes for gold (sodium bis[thiosulfato]gold[I]) intoxication in mice.

Eight compounds were examined to determine their relative efficacy as antidotes in acute gold intoxication in mice after the intraperitoneal injection of 200 mg/kg of Na3 [Au(S2O3)2] X 2H2O. Of the compounds examined, 2,3 dimercaptosuccinic acid was the most effective antidote. It was noted that with D-penicillamine those animals which did not survive died sooner (in a matter of hours) than the corresponding control animals which had received no antidote (about 3 days). In subsequent experiments in which Na3 [Au(S2O3)2] X 2H2O was administered at the lower level of 140 mg/kg, 2,3 dimercaptosuccinic acid showed itself to be capable of reducing kidney gold levels by a factor of about 5 and liver gold levels by a factor of approximately 2.

Animals↗
PubMed1984

Thiono compounds. 4. In vitro mutagenic and antineoplastic activity of TEPA and thio-TEPA.

Tris (1-aziridinyl) phosphine oxide (TEPA) and tris (1-aziridinyl) phosphine sulfide (thio-TEPA) induced base pair mutations in the Ames mutagenic assay. Thio-TEPA required metabolic activation while TEPA was active without metabolic activation. Growth of a human vaginal carcinoma (A431), a human breast carcinoma (MDA-MB-231), and a human cervical carcinoma (HeLa) were inhibited in soft agar in vitro at concentrations which induced mutagenesis in the Ames Assay. A fourth line, JEG choriocarcinoma, was sensitive to the antigrowth properties of both drugs at concentrations below that which induced mutagenesis. These data suggest that as more antineoplastic agents become available, and as mean survival times increase, knowledge of the relative in vitro sensitivity of a patient's neoplasm to a specific antineoplastic drug (i.e., dose required for growth inhibition) as a function of its mutagenic index might be useful for prediction of clinical remission, as well as the risk of secondary neoplasm induction.

Antineoplastic Agents↗
PubMed1984

Evidence that the collagen in the culture medium of Chinese hamster lung cells contains components related at the primary structural level to the alpha1(V) collagen chain.

The collagenous protein synthesized by cultured Chinese hamster lung (CHL) cells and present in the culture medium has been isolated after limited pepsin digestion and differential salt precipitation. Molecular size analysis of this material indicates that the CHL cell medium collagen contains chains which exhibit an apparent molecular mass of approximately 85,000 Da. When chromatographed on CM-cellulose under denaturing conditions, the reduced and alkylated CHL cell medium collagen chains elute slightly after the human alpha1(I) chain but well before the pepsin-derived alpha1(V) chain, which is the constituent chain present in the CHL cell cellular matrix collagen. Analysis of the peptides derived by CNBr cleavage of the CHL medium collagen chains by chromatography on CM-cellulose reveals, however, that these chains contain peptides which correspond both in size and in chemical properties to those derived from the alpha1(V) collagen chain, but clearly lack two peptides (alpha1(V)-CB4 and alpha1(V)-CB5) which are normally present in pepsin-derived alpha1(V) chains. Furthermore, analysis of the CHL cell culture medium collagenous material obtained without pepsin digestion indicates the presence of collagenous chains that exhibit after reduction a molecular mass of approximately 160,000 Da, which is smaller than the proposed size of the pro alpha1(V) collagen chain. These results demonstrate that the collagenous protein present in the culture medium of CHL cells is directly related at the primary structural level to the alpha1(V) collagen chain, and it is postulated that this material represents the large fragment derived from a collagenase cleavage of the [pro alpha1(V)]3 molecules present in the cell layer. Furthermore, these results and previous reports indicate that the only identifiable genetic type of procollagen chain synthesized by this cloned cell line in culture corresponds to the pro alpha1(V) chain.

Amino Acid Sequence↗
PubMed1984

Pleiotropic activities of human interferons are mediated by multiple response pathways.

Among the pleiotropic effects of human interferon are the inhibition of viral replication, the activation of natural killer cells, and the inhibition of cellular growth. Oxyphenbutazone, a nonsteroidal antiinflammatory agent, is a potent inhibitor of the antiviral activity of human alpha and beta interferons as determined by cytopathic effect and vesicular stomatitis virus synthesis and release in human foreskin fibroblasts. The inhibition of interferon activity is dose dependent with maximal inhibition at 25-50 microM and minimal inhibition at 1 microM. In contrast, oxyphenbutazone at concentrations as high as 100 microM has no effect on the activation of natural killer cells by human interferon. Similarly, oxyphenbutazone has no inhibitory effect on interferon-induced antigrowth activity in the human breast carcinoma cell line MDA-MB-231. This cell line is sensitive to oxyphenbutazone inhibition of interferon-induced antiviral activity in vitro. In another human cell line, the vulvar carcinoma A431, oxyphenbutazone apparently augments the antigrowth activity of interferon. Although oxyphenbutazone inhibits the fatty acid cyclooxygenase enzyme in these systems, other inhibitors of cyclooxygenase fail to inactivate the antiviral activity of human interferon. Thus, oxyphenbutazone appears to inhibit the interferon antiviral cascade at a site distinct from prostaglandin biosynthesis. Moreover, the failure to inhibit natural killer cell activation or cellular antigrowth effects of human interferon suggests a pathway different from that associated with the antiviral effect of human interferon.

Breast Neoplasms↗
PubMed1984

Comparison of histochemical and biochemical assays for estrogen receptor in human breast cancer cell lines.

Two human breast cancer lines, MCF-7 and T47D cells, were investigated for the presence of estrogen receptor (ER) by biochemical and histochemical techniques. Using the dextran-coated charcoal technique and isoelectric focusing, MCF-7 cells were ER positive, and T47D cells were ER negative. Fluorescein conjugates to 17 beta-estradiol by the sixth carbon (17 beta-estradiol-6-carboxymethyloxime:bovine serum albumin: fluorescein isothiocyanate and 17 beta-estradiol-6-iminooxyacetylfluoresceinamine) and by the 17th carbon [N-fluoresceino-N'-[17 beta-(estradiol hemisuccinamide)ethyl]thiourea, 17-FE] were prepared for cytochemical evaluation of the ER status of the two cell lines. The binding affinity of the estradiol conjugates for ER varied, the 17-FE conjugate having the highest affinity of 0.08 relative to 17 beta-estradiol. Following incubation with 10 nM 17-FE, both MCF-7 and T47D cells displayed cytoplasmic and nuclear fluorescent staining. Isoelectric focusing of MCF-7 cytosol incubated in the presence of 10 nM 17-FE revealed binding of the fluorescein conjugate to a protein species which did not bind 17 beta-[3H]-estradiol. Isoelectric focusing of T47D cytosol revealed binding of 17-FE to two protein components, neither one of which showed specific binding of 17 beta-[3H]estradiol. The results suggest different protein binding species for fluoresceinated estradiol conjugates and [3H]estradiol and help to explain reported differences in histochemical and biochemical ER analyses.

Breast Neoplasms↗
PubMed1984

Antiproliferative effect of vitamin A on xenotransplanted CaMa-15 cells.

In vitro and in vivo investigations have shown that nontoxic treatment with vitamin A (retinol) has an inhibitory effect on the growth of malignant cells. The tumorigenic CaMa -15 cell line responds to both retinol and retinoic acid under both anchorage-dependent and anchorage-independent conditions, reducing growth or colony formation by at least 50%. To date, there have been few studies on the effects of vitamin A on xenotransplanted neoplastic cells. Twenty-five adult female nude rats (rnu/rnu) were inoculated in the inguinal fat pad with 10(6) CaMa -15 cells, a tumorigenic epithelial cell line. The rats were divided into three groups: ten high dose (3 mg retinol/day i.p.); five low dose (30 micrograms retinol/day i.p.); and ten controls (corn oil i.p.). All animals were housed in specific-pathogen-free conditions and permitted access to sterile laboratory chow (5.4 micrograms retinol/g chow) and water ad libitum. Rats were sacrificed at 21 days after inoculation. Onset of tumor development occurred between Days 9 and 13 in all groups. Tumors grew progressively and were reduced in mean diameter by 26% (p = less than 0.05) with high-dose retinol and 44% (p = less than 0.02) by low-dose treatment. No clinical signs of vitamin A toxicity were apparent. Necropsy and radiological examination revealed no evidence of toxic effects or metastases. These results indicate that vitamin A can reduce the growth of xenotransplanted tumorigenic cells at nontoxic levels in T-cell-deficient hosts. The nude rat offers a potential model to study the inhibitory effects of retinoids on xenotransplanted cancers.

Animals↗
PubMed1983

Physical and chemical properties of human type III procollagen.

Type III procollagen was isolated from the serum-free culture media of human foreskin fibroblasts by adsorption to controlled-pore glass beads and chromatography of the eluted procollagen pool on diethylaminoethylcellulose [Gerard, S., & Mitchell, W. M. (1979) Anal. Biochem. 96, 433-447]. Sodium dodecyl sulfate (NaDodSO4) electrophoresis in 1% agarose-2% acrylamide gels with or without prior sample reduction revealed the predominance of a band with retarded mobility as compared to human procollagen I [hupro(I)]. Digestion of hupro(III) with pepsin yielded a product whose electrophoretic mobility was retarded for both the intact trimer and its reduced monomeric subunit as compared to that for the respective bands of rat skin (type I) collagen. NaDodSO4-polyacrylamide gel electrophoresis of bacterial collagenase-digested hupro(III) demonstrated disulfide-bonded propeptides which upon reduction were replaced by two distinct monomeric propeptide bands. The amino acid composition of hupro(III) was similar to that of hupro(I) but contained increased amounts of HO-Pro and Cys and less Thr, Ala, Val, and Arg. Sedimentation equilibrium analysis in 1 M CaCl2 yielded at extrapolated zero concentration a Mr of 505 +/- 25K. A [hupro(III) - collagen(III)] circular dichroic difference spectrum suggests approximately 10% alpha helix. The zero-order mutarotation rate of hupro(III) (vo = 55.0 X 10(-5) s-1) was twice that of hucol(III) (vo = 25.4 X 10(-5) s-1) at 20 degrees C, which may reflect the influence of the interchain disulfide-bonded carboxyl propeptides on the process of collagen fold formation.

Animals↗
PubMed1983

A functional cyclooxygenase enzyme is not required for mediation of the pleiotropic effects of human alpha or beta interferon.

Aspirin, indomethacin, and phenbutazone at 50 microM concentration inhibit cyclooxygenase in cultured human foreskin fibroblasts as evidenced by the suppression of the major prostaglandin species which accumulate in the culture medium. In contrast to data reported for mouse interferon on target mouse cells, these agents have no effect on the induction of antiviral activity by human alpha or beta interferons. Similarly, these agents have no effect on interferon induced inhibition of cell growth in vitro or on interferon induced natural killer cell activity.

Aspirin↗
PubMed1982

Antagonism of acute copper(II)-induced renal lesions by sodium 2,3-dimercaptopropanesulfonate.

Acute copper(II) sulfate poisoning in the mouse induces renal tubular degeneration and necrosis. Timely administration of sodium 2,3-dimercaptopropane-sulfonate (DMPS) effectively prevented the development of the morphological renal sequelae of copper intoxication. During the time course of this study (5 days), no copper-induced hepatic lesions were observed. DMPS and its preformed copper complex possess low inherent toxicity with no hepatorenal lesions occurring over a 5-day period. These findings suggest that DMPS may be an effective antidote in acute and chronic copper poisoning in humans.

Acute Kidney Injury↗
PubMed1981

Cell-free synthesis of putative type V procollagen chains programmed by Chinese hamster lung cell mRNA.

A messenger RNA fraction isolated from cultured Chinese hamster lung (CHL) cells programs in a cell-free system prepared from wheat germ the efficient incorporation of [14C] proline into newly synthesized protein with a significant fraction of the incorporated substrate being digestible with bacterial collagenase. This reaction requires both subcellular fractions, an energy source, and is inhibited by the antibiotic puromycin. The relative amount of collagenase-digestible to non-digestible cell-free product depends upon the ratio of CHL mRNA to wheat germ lysate, is not affected by either the Mg2+ or K+ concentrations employed, and under optimal condition, approximately 38% of the total incorporated substrate is collagenase-sensitive. Electrophoresis on SDS-polyacrylamide gels of the products programmed by CHL mRNA indicates that the collagenase-digestible material corresponds in size to a procollagen chain with an apparent molecular mass of approximately 170,000 daltons. These studies suggest that the collagen alpha 1 (V) chain is initially synthesized as a precursor procollagen chain and demonstrate that a significant amount of the mRNA in Chinese hamster lung cells codes for this protein.

Animals↗