Biomedical subjects

K Eitel

Publications and source records attributed to K Eitel.

3 recordsLinked to original sources

PubMed2003

Improved limits on nu(e) emission from mu+ decay.

We investigated mu(+) decays at rest produced at the ISIS beam stop target. Lepton flavor (LF) conservation has been tested by searching for nu(e) via the detection reaction p(nu(e),e(+))n. No nu(e) signal from LF violating mu(+) decays was identified. We extract upper limits of the branching ratio (BR) for the LF violating decay mu(+)-->e(+)+nu(e)+nu(-) compared to the standard model (SM) mu(+)-->e(+)+nu(e)+nu(mu) decay: BR<0.9(1.7) x 10(-3) (90% C.L.) depending on the spectral distribution of nu(e) characterized by the Michel parameter rho=0.75(0.0). These results improve earlier limits by one order of magnitude and restrict extensions of the SM in which nu(e) emission from mu(+) decay is allowed with considerable strength. The decay mu(+)-->e(+)+nu(e)+nu(mu) often proposed as a potential source for the nu(e) signal observed in the LSND experiment can be excluded.

Journal Article↗

PubMed1999

Inhibition of drug-induced DNA fragmentation, but not cell death, of glioma cells by non-caspase protease inhibitors.

The role of non-caspase protease activation in drug-induced cell death of glioma cells was examined. Neither calpain inhibitors I or II, phenylmethylsulfonyl fluoride (PMSF), Nalpha -p-tosyl-L-lysine chloromethyl ketone (TLCK), N-tosyl-L-phenylalanine chloromethyl ketone (TPCK), E64, leupeptin nor pepstatin inhibit the cytotoxicity of vincristine, cisplatin, doxorubicin, cytarabine, camptothecin, BCNU or VM26 in two malignant glioma cell lines, T98G and LN-229. However, DNA fragmentation induced by VM26 is inhibited by calpain inhibitor I, PMSF, TLCK and TPCK, and that induced by camptothecin by calpain inhibitors I and II and TPCK. Moreover, protease inhibitors fail to abrogate CD95 ligand-induced apoptosis even though DNA fragmentation is attenuated by calpain inhibitor II and TPCK. Thus, non-caspase protease activation is not required for drug-induced apoptosis of glioma cells. Protease inhibitor-mediated inhibition of DNA fragmentation operates downstream of the commitment point for cell death.

Antineoplastic Agents↗

PubMed1999

Proteasome inhibitors induce p53/p21-independent apoptosis in human glioma cells.

The proteasome is a multiprotein complex involved in the degradation of ubiquitinated proteins. Three proteasome inhibitors, calpain inhibitor I, lactacystin and MG132, induced apoptosis in several human malignant glioma cell lines. Although proteasome inhibitors induced p53 accumulation in a cell line retaining wild-type p53 activity, p53 activity was dispensable for apoptosis since transdominant-negative p53 abrogated p53-dependent p21 induction but did not modulate apoptosis. Further, p21 was induced by higher concentrations of proteasome inhibitors in a p53-independent manner both in p53 wild-type and in p53 mutant cell lines. Although there was a strong G2/M arrest in response to proteasome inhibition in glioma cells, this G2/M arrest was also observed in p21(-/-) colon carcinoma cells, suggesting that p21 is dispensable for the G2/M arrest associated with proteasome inhibition. Interestingly, the p21(-/-) cells were more resistant to protease inhibitors than parental p21(+/+) cells. In summary, our data indicate that proteasome inhibition induces a p21-independent G2/M arrest and p53-independent apoptosis in human malignant glioma cells.

Acetylcysteine↗