PubMed Health⌕ Search

Biomedical subjects

C Carruthers

Publications and source records attributed to C Carruthers.

At least 19 recordsLinked to original sources
PubMed2001

Transmission of hepatitis C in a pharmacologic study.

OBJECTIVE: To describe an outbreak of hepatitis C in a clinical research study. DESIGN: Observational study. SETTING: Tertiary-care hospital. PATIENTS: Healthcare workers who volunteered to be subjects in a study of the metabolic effects of inhaled and oral corticosteroids who were unwittingly exposed to hepatitis C virus (HCV). METHODS: Epidemiological investigation and serological analyses. RESULTS: One chronic carrier of HCV was identified. Four fellow workers volunteering in the studies became infected with HCV, with 96% homology among strains. There was no evidence of spread from infected healthcare workers to patients on whom they had performed arterial punctures (2 of 214 positive, unrelated to each other and to the outbreak strain). CONCLUSION: Infection control standards in clinical research must be maintained vigorously to prevent transmission of blood-borne pathogens such as HCV.

Adrenal Cortex Hormones↗
PubMed1995

Saying goodbye to Canada's single-payer system.

Cost shifting, in which governments transfer the cost of certain health care services to patients or private insurance companies, is increasing rapidly, and Dr. Christopher Carruthers thinks it will spell an end to Canada's single-payer system. The signs are already there: the private sector is offering more services and employers are keeping a closer eye on the health care system as they begin to pay a bigger share of the costs. The result, says Carruthers, is that government influence is bound to diminish as the private sector tries to fill voids created by governments that are trying to live within their fiscal means.

Canada↗
PubMed1993

Direct role for Myc in transcription initiation mediated by interactions with TFII-I.

The nuclear proto-oncoprotein Myc has been implicated in the control of cell proliferation and differentiation. Myc participates in transcription and belongs to the basic-helix-loop-helix (bHLH) family of regulatory proteins. Here we show that Myc interacts with TFII-I, a transcription initiation factor that activates core promoters through an initiator element (Inr). As previously observed for the bHLH activator USF, Myc was found to interact cooperatively with TFII-I at both Inr and upstream E-box promoter elements. However, in this case Myc interactions with TFII-I at the Inr lead to an inhibition of transcription initiation. This inhibition is selective for a TFII-I-dependent (as opposed to TFIIA-dependent) initiation pathway and correlates with the prevention of complex formation between the TATA-binding protein TBP (TFIID tau), TFII-I and the promoter. TBP probably interacts with Myc, but only slowly. These observations indicate that Myc has the potential to interact physically and functionally with components of the general transcription machinery.

Adenoviridae↗
PubMed1983

Effect of 12-O-tetradecanoyl-phorbol-13-acetate and 3-methylcholanthrene on the toxicity of nicotine applied to mouse skin.

The effect of the tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and 3-methylcholanthrene (MCA) on the toxicity of nicotine and the content of this alkaloid in mouse skin has been determined following the application of these reagents to the skin. TPA or MCA was applied to mouse skin at time 0, and then at various time intervals thereafter, nicotine was applied to the skin. The content of this alkaloid (nicotine DNA ratio) remaining in the skin was then determined 1/2 h after its application. After the application of TPA, the nicotine DNA ratio of the skin decreased from 120 at 1.8 h to 80 at 18 h, increased sharply from 24 h, reaching a maximum of 165 at 72 h, and then decreased gradually. As the nicotine DNA ratio of the skin increased, the mortality rate of the mice also increased, reaching a maximum of over 40% at 48 and 72 h following the application of TPA. When MCA was applied to mouse skin in the same fashion and then nicotine, there was a decrease in the nicotine DNA ratio similar to that induced by TPA and nicotine followed by an average increase in the nicotine DNA ratio of 130 at 72, 96 and 120 h. The mortality rate of these mice was low. Finally, ethyl phenyl propiolate (EPP) was applied to mouse skin at time 0, and nicotine was applied 24, 48, 72, 96 and 120 h later. The mortality rate was also quite low at these times 1/2 h after application of nicotine (nicotine was not determined in the skin). TPA has induced some change in the skin 24, 48, 72 and 96 h after its application which resulted in an increase in the toxicity of nicotine to mice. Nicotine was not detected by the gas chromatographic method employed in the serum or plasma of nicotine-treated and TPA and nicotine-treated mice even though the mice showed acute reactions of nicotine toxicity and the skin surface contained ample amounts of this alkaloid.

Administration, Topical↗
PubMed1982

Effect of the tumor promotor 12-O-tetradecanoylphorbol-13-acetate on the rate of disappearance of nicotine from mouse skin.

The rate of disappearance of nicotine from mouse skin was increased by the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA) during the first 2-hour period following the application of nicotine to mouse skin. The biological half-life (t1/2) for nicotine alone was 1.2-1.3 h whereas in the presence of TPA, t1/2 was 0.8 to 0.9 h. The disappearance of nicotine from mouse skin followed first-order kinetics over a period of 6 h whereas the loss of nicotine in the presence of TPA from mouse skin followed first-order kinetics for the first 2 h, then the nicotine level became fairly constant for the time period of 2-5 h. Benzo (alpha) pyrene did not affect the rate of disappearance of nicotine from mouse skin. Neither cotinine nor nicotine 1'-N oxide, metabolites of nicotine, was detected in mouse skin following the topical application of this alkaloid.

Administration, Topical↗
PubMed1980

Ligandin content of normal and carcinogen-treated rat tissues.

Ligandin was detected by immunofluorescence in tissue sections and determined by immunoquantitation in the cytosols of the liver, kidney and testes of normal and carcinogen-treated rats. Ligandin was not detected by either of these procedures in normal or carcinogen-treated rat lung, spleen, brain, and skeletal or cardiac muscle.

Animals↗
PubMed1979

Detection by antihapten antibodies of liver-bound compounds related to azocarcinogens or their metabolites.

The localization of known azocarcinogens and metabolites such as p-aminoazobenzene and N-methyl-p-aminoazobenzene bound to components of liver cells of rats fed single or multiple doses of 3'-methyl-p-dimethylaminoazobenzene has been determined with the use of antibodies raised against p'-azo-p-aminoazobenzene and p'-azo-N-monomethyl-p-aminoazobenzene in the indirect fluorescent antibody procedure. These 2 antisera reacted with liver cells of rats fed 3'-methyl-p-dimethylaminoazobenzene, p'-amino-p-aminoazobenzene, p'-amino-N-monomethyl-p-aminoazobenzene and N-methyl-p-aminoazobenzene. The results obtained in this study suggest that both major and minor metabolites of azocarcinogens have common antigenic determinants.

Animals↗
PubMed1979

Distribution of ligandin in normal and azocarcinogen-treated rat liver and azocarcinogen-induced liver tumors.

Antibodies were raised in rabbits against pure ligandin. Employing the fluorescent antibody procedure, an antigen identical to ligandin was shown to be uniformly distributed in the hepatic cells of both normal rat liver and in early and late 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB)-treated liver. Ligandin was absent in liver carcinomas induced by this azocarcinogen. The results obtained with fluorescent antibody procedure were confirmed by the immunoquantitation of ligandin in the cytosols prepared from normal rat liver, early and late 3'-Me-DAB-treated liver, mixtures of both late 3'-Me-DAB-treated liver and liver carcinomas and liver carcinomas. Riboflavin-deficient diets lowered significantly the hepatic ligandin content.

Animals↗
PubMed1977

A distinctive antigen present in liver carcinomas induced by 3'-methyl-p-dimethylaminoazobenzene.

Hepatocellular carcinomas and cholangiocarcinomas induced in rat liver by the administration of 3'-methyl-p-dimethyl-aminoazobenzene (3'-Me-DAB) were found to contain a carcinoma distinctive antigen by immunofluorescence, immunoelectrophoresis and immunodiffusion. This carcinoma distinctive antigen does not appear to be alpha-fetoprotein (AFP) or the preneoplastic antigen.

Adenoma, Bile Duct↗
PubMed1976

Detection of liver-bound metabolites of azocarcinogens by the use of anti-hapten antibodies.

The presence of the azocompounds, p-dimethylaminoazobenzene and 3'-methyl-p-dimethylaminoazobenzene, and p-amino-N-acetyl-N-methylaniline (or their metabolites) bound to components of the liver cells of rats fed a single large dose of each compound has been detected using rabbit antibodies raised against the p-azo-N-acetyl-N-methylaniline hapten in the indirect fluorescent antibody technique. Binding of these antibodies was seen on liver sections from rats fed any one of these compounds. When the anti-p-azo-N-acetyl-N-methylaniline antiserum was absorbed with either liver sediments or cytosol fractions from rats fed p-amino-N-acetyl-N-methylaniline, the antibodies reacting with the liver-bound compounds were removed from the antiserum. Also, absorption of the antiserum with liver sediments or cytosol fractions of rats fed either one of the azocompounds selectively removed all of the antibodies reacting with the livers of rats fed that compound but did not remove other antibodies that were still capable of reacting with liver cells of rats fed the other azocompound or p-amino-N-acetyl-N-methylaniline. Thus this antiserum appears to contain several different anti-p-azo-N-acetyl-N-methylaniline antibodies with different structural requirements for reaction. Some can react with the azocompounds or certain of their metabolites, while others require more of the p-azo-N-acetyl-N-methylaniline structure for reaction. Some of the antibodies appear to react with liver-bound p-dimethylaminoazobenzene but not with liver-bound 3'-methyl-p-dimethylaminoazobenzene, while still others react with 3'-methyl-p-dimethylaminoazobenzene but not with p-dimethylaminoazobenzene.

Aniline Compounds↗
PubMed1975

Immunological escape mechanism in spontaneously metastasizing mammary tumors.

Immunological and biochemical studies of spontaneously metastasizing and nonmetastasizing rat mammary carcinomas and their plasma membranes indicated that: (i) all spontaneously metastasizing tumors have little or no demonstrable glycocalyx, while all nonmetastasizing tumors have a thick glycocalyx; (ii) there is a direct relationship between the glycocalyx and immunogenicity, and an inverse relationship with the metastasizing capacity of tumor cells, properties which can be quantitated by levels of the plasma membrane marker enzyme 5'-nucleotidase (EC3.1.3.5;5'-ribonucleotide phosphohydrolase) activity; (iii) the absence of glycocalyx from the metastasizing tumor cell surface seems to result from its dissociation from plasma membranes, for solubilized cell surface antigen is readily found in the blood of metastasizing tumor bearing rats, while there was no detectable tumor cell surface antigen in the blood of the nonmetastasizing tumor hosts tested; (iv) both metastasizing and nonmetastasizing mammary tumors appear to have a common soluble cell surface antigen; (v) in addition to this common antigen, there is another membrane-bound antigen in the nonmetastasizing, immunogenic tumor cell surface which presumably is the tumor specific transplantation antigen; and (vi) this antigen is immunobiologically unique, but seems to be immunochemically related to the common soluble antigen. It is postulated that the lack of an immunogenic coat and/or the presence of solubilized tumor cell surface antigen in the blood may provide an immune escape mechanism for tumor cells by interfering with cell-mediated immune response of tumor hosts, leading to their dissemination.

Animals↗
PubMed1975

Heterogeneity of bovine snout epidermal prekeratin.

The prekeratin of the snout of cows was extracted with 0-1 mol/l citric acid-sodium citrate buffer, pH 2-6. The results of equilibrium ultracentrifugation analyses of this prekeratin strongly suggest that this protein is not homogeneous. This conclusion is in accordance with the observations of two other investigators whose data infer that there is no major homogeneous keratin precursor in cow's lip or snout epidermis.

Animals↗
PubMed1975

Binding of the azocarcinogen 3'-methyl-p-dimethylaminoazobenzene to cellular components of normal rat liver and azocarcinogen-induced hepatomas.

The location of binding sites for 3'-methyl-p-dimethylaminoazobenzene (3'-Me-DAB) or metabolites on components of rat liver cells and hepatoma cells in tumors induced by this carcinogen was determined at 2 stages during the induction of tumors in rats: (a) in normal liver immediately following the application of a massive dose of the azocarcinogen by intragastric feeding, and (b) in liver and tumor after hepatomas had developed following repeated exposures to the carcinogen by s.c. injections. Bound 3'-Me-DAB or metabolites were detected by the use of rabbit antisera directed against either p-azoazobenzene or p'-azo-p-dimethylaminoazobenzene in an indirect fluorescent antibody technique. Soon after massive intragastric doses of 3'-Me-DAB, the staining observed when the anti-p-azoazobenzene antiserum was used was principally on cytoplasmic components of liver cells with some staining of the intranuclear components. When the second antiserum, anti-p'-azo-p-dimethylaminoazobenzene antiserum, was used, the most intense fluorescent staining was on the nuclear membranes, although there was some cytoplasmic and intranuclear staining as well.

Adenoma, Bile Duct↗