Biomedical subjects

J Karras

Publications and source records attributed to J Karras.

4 recordsLinked to original sources

PubMed2001

Inhibition of STAT3 signaling leads to apoptosis of leukemic large granular lymphocytes and decreased Mcl-1 expression.

Large granular lymphocyte (LGL) leukemia is characterized by the expansion of antigen-activated cytotoxic T lymphocytes. These leukemic cells are resistant to Fas-mediated apoptosis despite expressing high levels of Fas. We found that leukemic LGL from 19 patients displayed high levels of activated STAT3. Treatment of leukemic LGL with the JAK-selective tyrosine kinase inhibitor AG-490 induced apoptosis with a corresponding decrease in STAT-DNA binding activity. Moreover, using an antisense oligonucleotide approach to diminish STAT3 expression, we found that Fas sensitivity was restored in leukemic LGL. AG-490-induced apoptosis in leukemic LGL was independent of Bcl-xL or Bcl-2 expression. However, we found that the Bcl-2-family protein Mcl-1 was significantly reduced by AG-490 treatment. Activated STAT3 was shown to bind an SIE-related element in the murine mcl-1 promoter. Using a luciferase reporter assay, we demonstrated that v-src overexpression in NIH3T3 induced STAT3-dependent transcriptional activity from the mcl-1 promoter and increased endogenous Mcl-1 protein levels. We conclude that STAT3 activation contributed to accumulation of the leukemic LGL clones. These findings suggest that investigation should focus on novel strategies targeting STAT3 in the treatment of LGL leukemia.

Apoptosis↗

PubMed1994

The distribution of omega-conotoxin MVIICnle-binding sites in rat brain measured by autoradiography.

An analogue of omega-conotoxin MVIIC, [125I]omega-MVIICnle, has been employed in an autoradiographic assay to define the distribution of binding sites in rat brain of this neuronal calcium channel antagonist. In comparison with N-type channels (labeled by [125I]omega conotoxin GVIA), omega-MVIICnle sites are much denser in cerebellum (molecular layer) than in forebrain. Binding in thalamus is also comparatively high for omega-MVIICnle. Under these conditions, [125I]omega-MVIICnle binding to rat brain sections is not displaceable by the N-channel antagonist, omega-conotoxin GVIA. The calcium channel blocker [125I]omega-conotoxin MVIICnle labels a unique set of binding sites in mammalian brain.

Animals↗

PubMed1983

Determination of canrenone, the major metabolite of spironolactone, in plasma and urine by high-performance liquid chromatography.

An assay procedure for measuring plasma and urine levels of canrenone is described. The drug is extracted with n-hexane-toluene (1:1, v/v) after adding spirorenone as internal standard, and is then separated from plasma constituents and metabolites by high-performance liquid chromatography followed by UV detection at 285 nm. The limit of detection is less than 5 ng/ml. Interference with a series of spironolactone and canrenone metabolites was not observed. Plasma levels and renal excretion of canrenone after oral administration of 200 mg of spironolactone and intravenous injection of 200 mg of potassium canrenoate to a healthy male volunteer were measured.

Administration, Oral↗

PubMed1983

Pharmacokinetics of canrenone after oral administration of spironolactone and intravenous injection of canrenoate-K in healthy man.

Five healthy male volunteers received canrenoate-K 200 mg (Sincomen pro injectione) by intravenous injection and one week later spironolactone 200 mg (Sincomen-100) orally. Plasma levels and urinary excretion of unchanged canrenone were determined up to 24 h by a specific HPLC method. Following intravenous administration, the maximum plasma level of 2066 +/- 876 ng/ml was found after 29 +/- 15 min and thereafter the concentration declined with a half-life of 3.7 +/- 1.2 h. Total clearance was 4.2 +/- 1.7 ml/min . kg. After oral ingestion, the maximum concentration of 177 +/- 33 ng/ml was observed at 4.4 +/- 0.9 h. The absolute bioavailability of canrenone was 25 +/- 9%. Within 24 h, respectively 0.4 and 0.6 mg, canrenone were excreted by the kidney after intravenous and oral administration. The half-life of elimination was 4.9 +/- 1.8 h (i.v.) and 3.9 +/- 1.2 h (p.o.).

Administration, Oral↗