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G Stauffer

Publications and source records attributed to G Stauffer.

6 recordsLinked to original sources
PubMed2001

Induction of glutathione S-transferase activity and protein expression in brown bullhead (Ameiurus nebulosus) liver by ethoxyquin.

The inducibility of hepatic cytosolic glutathione S-transferases (GSTs) was examined in brown bullheads, a freshwater fish that is highly susceptible to hepatic neoplasia following exposure to carcinogen-contaminated sediments. Juvenile bullheads were fed a semi-purified antioxidant-free diet supplemented with ethoxyquin (0.5% w/w dissolved in 3% corn oil), a prototypical rodent GST-inducing agent, twice daily for 14 days. Control bullheads received the antioxidant-free diet supplemented with corn oil (3% w/w). A significant increase (1.6-fold, p < or = 0.01) in hepatic cytosolic GST activity toward 1-chloro-2,4-dinitrobenzene (CDNB) was observed in the ethoxyquin-treated bullheads relative to control fish. A trend toward increased GST-NBC activity was observed in the ethoxyquin-treated fish (1.2-fold, p = 0.06), whereas no treatment-related effects were observed on GST activities toward ethacrynic acid (ECA). In contrast, GST activity toward (+/-)-anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide (BPDE) was repressed in affinity-purified cytosolic fractions prepared from ethoxyquin-treated bullheads relative to control bullheads. Silver staining and densitometric analysis of isoelectric-focused, affinity-purified GST proteins revealed increased expression of two basic GST-like isoforms in ethoxyquin-treated fish. In summary, exposure to ethoxyquin increases brown bullhead GST-CDNB catalytic activity and hepatic cationic GST protein expression. However, the increase in overall GST-CDNB activity by ethoxyquin is associated with repression of GST-BPDE activity, suggesting differential effects on hepatic bullhead GST isoforms by ethoxyquin. The potential repression of bullhead GST isoforms that conjugate the carcinogenic metabolites of PAH metabolism under conditions of environmental chemical exposure could be a contributing factor in the sensitivity of bullheads to pollutant-associated neoplasia.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1996

Homocysteine antagonism of nitric oxide-related cytostasis in Salmonella typhimurium.

Nitric oxide (NO) is associated with broad-spectrum antimicrobial activity of particular importance in infections caused by intracellular pathogens. An insertion mutation in the metL gene of Salmonella typhimurium conferred specific hypersusceptibility to S-nitrosothiol NO-donor compounds and attenuated virulence of the organism in mice. The metL gene product catalyzes two proximal metabolic steps required for homocysteine biosynthesis. S-Nitrosothiol resistance was restored by exogenous homocysteine or introduction of the metL gene on a plasmid. Measurement of expression of the homocysteine-sensitive metH gene indicated that S-nitrosothiols may directly deplete intracellular homocysteine. Homocysteine may act as an endogenous NO antagonist in diverse processes including infection, atherosclerosis, and neurologic disease.

Animals↗
PubMed1994

[How long should cyclosporin be administered following bone marrow transplantation?].

After organ transplantation, life-long immunosuppression is mandatory to prevent rejection. This is not the case after allogeneic bone marrow transplantation (BMT). The mechanisms of tolerance are little understood and there is little data about the required duration of immunosuppression. In a retrospective study we analyzed the use of cyclosporine A (CyA) treatment in all BMT patients who where transplanted in Basel from 1979 to 1991. 243 patients with a median age of 26 (2-49) years received CyA to prevent graft-versus-host-disease (GvHD) and rejection. 206 patients had leukemia, 26 severe aplastic anemia and 10 a lymphoproliferative disorder. All were treated according to a common CyA regimen with initial parenteral administration followed by oral treatment for a year; after 1988 treatment duration was reduced to 6 months. Drug dosage was adjusted according to clinical symptoms, plasma levels and toxicity. At relapse of the original disease CyA was always withdrawn. Three months after BMT 96% were still on CyA. After 6 months 79%, after 1 year 61%, after 2 years 29%, after 3 years 18%, after 4 years 15%, after 5 years 8% and after 8 years 2% of patients were still taking CyA. All 20 patients who are still alive 10 years after BMT are off CyA. CyA was administered parenterally for a median of 31 (5-147) days. Oral treatment started at day 25 (4-28). The oral dose was reduced 5 (1-20) times, increased once (1-75) and finally discontinued after a median time lapse of 1 year (14d-8y).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[Isolation ward: initial experiences after 4 years].

UNLABELLED: Since October 1988 there has been an isolation ward at Basle Cantonal Hospital. Its purpose is to treat patients with high dose chemotherapy and bone marrow transplantation under protective isolation and by standardized criteria. The isolation ward has two sub-units, viz. the reverse isolation for neutropenic patients (8 single room units) and the LAF unit (5 laminar airflow units) for allogeneic bone marrow transplantation (BMT). Up to July 1992, 287 patients (152 males and 133 females) required 527 hospitalizations. The median age was 41 (5-82) years in the reverse isolation unit and 28 (4-61) years in the LAF unit. Bed occupation was 90% and 82% throughout the period. 71% of patients were from the Basle area and the rest from elsewhere in Switzerland or from other countries. DIAGNOSIS: acute leukemias (112); myelodysplastic or myeloproliferative syndromes (52); severe aplastic anemia or agranulocytosis (46); lymphoproliferative syndromes (50); solid tumors (28). Indications for hospitalisation: BMT (107); complications after BMT (infections, GvHD) (63); chemotherapy on protocols of SAKK (105); other chemotherapies (64); antilymphocyte globulin or growth factor treatment (27); splenectomies (18); neutropenic fever (62); patient work-up (59); terminal care (20). Patients in reverse isolation were hospitalized for a median 17 (1-142) days; in the LAF unit for 52 (1-121) days.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Regulation of methionine synthesis in Escherichia coli: effect of the MetR protein on the expression of the metE and metR genes.

A plasmid (pRSE562) containing the metE and metR genes of Escherichia coli was used to study the expression of these genes and the role of the MetR protein in regulating metE expression. DNA sequence analysis of the 236-base-pair region separating these genes showed the presence of seven putative met boxes. When this plasmid was used to transform either wild-type E. coli, metE mutant, or metR mutant, MetE enzyme activity increased 5- to 7-fold over wild-type levels. The metR gene was subcloned from pRSE562, and this plasmid, pMRIII, relieved the methionine auxotrophy of a metR mutant after transformation. The metR gene was also cloned into a vector containing the lambda PL promoter, and the MetR protein was overexpressed and purified to near homogeneity. This protein, when added to an in vitro DNA-dependent protein synthesis system in which the MetE and/or MetR proteins were synthesized, caused a large increase in the expression of the metE gene but a decrease in the expression of the metR gene. The in vitro expression of both genes was inhibited by the MetJ protein and S-adenosylmethionine in the presence or absence of MetR protein. These results provide evidence that the product of the metR gene is a trans-activator of the expression of the metE gene and that the expression of the metR gene is under autogenous regulation and is repressed by the MetJ protein.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗