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Biomedical subjects

M Fitzek

Publications and source records attributed to M Fitzek.

6 recordsLinked to original sources
PubMed1993

Clonal heterogeneity in delayed decrease of plating efficiency of irradiated HeLa cells.

The clonogenic potential of progeny of irradiated HeLa cells was studied at different times after single doses of 4-12 Gy. The dose-dependent decrease in plating efficiency that was observed resembled the effect termed "delayed lethal mutation" by Seymour et al. (1986). The effect decreased with time after irradiation. Individual clones of irradiated and non-irradiated cells were isolated, expanded and replated 5 weeks after irradiation, i.e., after between 200,000 and 1,000,000 progeny had formed from the individual parent cell. The plating efficiency of progeny of unirradiated cells did not vary much, whereas clonal progeny of irradiated cells had plating efficiencies ranging from 3% to 76%. The plating efficiency was not related to the cell number in the original clone.

Cell Survival↗
PubMed1992

Serum markers for primary and recurrent breast cancer: BCM-EIA, CAM 26 and CAM 29.

Three sandwich enzyme immunoassays were used to evaluate serum from 93 women: 20 normal, 20 with benign breast disease, 22 with primary and 31 with recurrent breast cancer. Using the three assays, breast cancer mucin enzyme immunoassay (BCM-EIA) carcinoma-associated mucin antigen (CAM) 26 and CAM 29, both singly and in combination, we were unable to establish meaningful cut-offs to differentiate between patients with or without breast cancer. The sensitivity and specificity for BCM-EIA were 90% and 40%, for CAM 26, 89% and 42%, and for CAM 29, 91% and 66%, respectively. Serial serum specimens from 29 patients with recurrent breast cancer were assayed. At recurrence, an increase of 25% or more in marker level over the previous value was found in 24/29 (83%) BCM results, 14/29 (48%) CAM 26 results and 12/29 (41%) CAM 29 results. Prior to clinical detection of recurrence, stepwise increases in BCM and CAM 26 marker levels were seen up to 299 days prior to clinical detection of recurrence. We conclude that these markers may help in the early detection of recurrent breast cancer.

Antigens, Neoplasm↗
PubMed1988

Vectors for efficient expression in mammalian fibroblastoid, myeloid and lymphoid cells via transfection or infection.

We have constructed two related types of multi-cloning mammalian expression vectors. The first, pMPSVEH/HE, carries the promoter of the myeloproliferative sarcoma virus (MPSV). This promoter was found to be stronger than both the SV40 early and the trans-activated human immunodeficiency virus promoters in many cell lines including human and rodent fibroblastoid, lymphoid or myeloid cells. The other, pBEH/HE, carries the simian virus 40 (SV40) early promoter and origin of replication. This offers the possibility of encapsidation in SV40 pseudovirions and subsequent gene transfer into, e.g., hemopoietic cells, via infection. The usefulness of the expression systems was tested with a number of genes and cell lines.

Animals↗
PubMed1988

His+ reversions caused in Salmonella typhimurium by different types of ionizing radiation.

The yield of his+ reversions in the Ames Salmonella tester strain TA2638 has been determined for 60Co gamma rays, 140 kV X rays, 5.4 keV characteristic X rays, 2.2 MeV protons, 3.1 MeV alpha particles, and 18 MeV/U Fe ions. Inactivation studies were performed with the same radiations. For both mutation and inactivation, the maximum effectiveness per unit absorbed dose was obtained for the characteristic X rays, which have a dose averaged linear energy transfer (LET) of roughly 10 keV/micron. The ratio of the effectiveness of this radiation to gamma rays was 2 for inactivation and about 1.4 for the his+ reversion. For both end points the effectiveness decreases substantially at high LET, i.e., for the alpha particles and the Fe ions. The composition of the bottom and the top agar was the one recommended by Maron and Ames [Mutat. Res. 113, 173-215 (1983)] for application in chemical mutagenicity tests. The experiments with the less penetrating radiations differed from the usual protocol by utilization of a technique of plating the bacteria on the surface of the top agar. As in an earlier study [Roos et al., Radiat. Res. 104, 102-108 (1985)] greatly enhanced yields of mutations, relative to the spontaneous reversion rate, were obtained in these experiments by performing the irradiations 6 h after plating, which differs from the conventional procedure to irradiate the bacteria shortly after plating.

Alpha Particles↗