Biomedical subjects

K Kopitzki

Publications and source records attributed to K Kopitzki.

4 recordsLinked to original sources

PubMed2006

Genetic and metabolic predictors of chemosensitivity in oligodendroglial neoplasms.

The -1p/-19q genotype predicts chemosensitivity in oligodendroglial neoplasms, but some with intact 1p/19q also respond and not all with 1p/19q loss derive durable benefit from chemotherapy. We have evaluated the predictive and prognostic significance of pretherapy (201)Tl and (18)F-FDG SPECT and genotype in 38 primary and 10 recurrent oligodendroglial neoplasms following PCV chemotherapy. 1p/19q loss was seen in 8/15 OII, 6/15 OAII, 7/7 OIII, 3/11 OAIII and was associated with response (Fisher-Exact: P=0.000) and prolonged progression-free (log-rank: P=0.002) and overall survival (OS) (log-rank: P=0.0048). Response was unrelated to metabolism, with tumours with high or low metabolism showing response. Increased (18)F-FDG or (201)Tl uptake predicted shorter progression-free survival (PFS) in the series (log-rank: (201)Tl P=0.0097, (18)F-FDG P=0.0170) and in cases with or without the -1p/-19q genotype. Elevated metabolism was associated with shorter OS in cases with intact 1p/19q (log-rank: (18)F-FDG P=0.0077; (201)Tl P=0.0004) and shorter PFS in responders (log-rank: (18)F-FDG P=0.005; (201)Tl P=0.0132). (201)Tl uptake and 1p/19q loss were independent predictors of survival in multivariate analysis. In this initial study, (201)Tl and (18)F-FDG uptake did not predict response to PCV, but may be associated with poor survival following therapy irrespective of genotype. This may be clinically useful warranting further study.

Adult↗

PubMed2003

Interstitial stereotactic radiosurgery.

Stereotactic radiosurgery by means of interstitial application of either radionuclides or radiation devices has been used extensively in primary and secondary brain tumors. A few centers have gained sufficient expertise and clinical data to scientifically evaluate this treatment modality. Interstitial stereotactic radiosurgery is limited to circumscribed lesions with a diameter of 3.5 cm or less. The radiobiology of interstitial radiosurgery is quite well elaborated as to doses, dose rates and effects on vascular physiology. Efficacy in low grade gliomas is well documented by several European centers using 125-J sources. Different modes of implantation have been used and evaluated including single fraction treatment using a miniature linear accelerator (Photoelectron). In malignant gliomas interstitial radiosurgery has been investigated in a prospective, randomised, controlled trial and not shown to be effective. Steretactic interstitial radiosurgery is a powerful treatment option in circumscribed CNS tumors like some low grade gliomas and metastasis but does play no major role in the treatment of malignant glioma.

Animals↗

PubMed2002

Comment on "Kullback-Leibler and renormalized entropies: applications to electroencephalograms of epilepsy patients".

In a recent paper Quian Quiroga et al. [R. Quian Quiroga et al., Phys. Rev. E 62, 8380 (2000)] found renormalized entropy, formerly introduced as a complexity measure for the different regimes of a dynamical system, to be closely related to the standard Kullback-Leibler entropy. They assure this finding by reanalyzing electroencephalographic data of epilepsy patients, previously examined by exclusive use of renormalized entropy [K. Kopitzki et al., Phys. Rev. E 58, 4859 (1998)]. We argue that the general considerations undertaken by the authors and the experimental results do not justify this conclusion.

Data Interpretation, Statistical↗

PubMed2000

Early effects of PRS-irradiation for 9L gliosarcoma: characterization of interphase cell death.

We characterized the interphase cell death of 9L gliosarcoma after high-dose-rate, low-energy photon irradiation using the Photon Radiosurgery System (PRS), a novel device for interstitial radiotherapy. Within 24 hours after irradiation with a dose of 18 Gray, 22.0% of cells underwent metabolic cell death, whereas dead cells in controls stayed less than 5.0% (p<0.005). In the majority of sensitive cells, loss of membrane integrity preceded the lethal morphological changes. The response was dose-dependent over the range of 9-18 Gray, but saturation was obtained over 18 Gray. On the other hand, a significant (p < 0.01) increase in the number of TUNEL-positive cells with apoptotic morphology was detected 6-24 hours after irradiation, but the fraction remained 1.9-2.1% of the population and was independent of the doses between 9 and 25 Gray. Apoptotic cells were rarely observed in the control cells (0.3-0.6%). Our data indicate that single high-dose irradiation induces both necrotic and apoptotic interphase cell death in 9L gliosarcoma, but rapid cell death mostly occurs through the non-apoptotic pathway.

Apoptosis↗