Biomedical subjects
Publications and source records attributed to D Linder.
Under the assumption that benign ovarian teratomas arise parthenogenetically from a germ cell by suppression of the second meiotic division, the proportion gamma of heteratomas collected from heterozygous hosts is a measure for the distance between the corresponding gene and its centromere. For proportions gamma less than or equal to 0.3, the mapping function x = gamma/2 applies, where x is the map distance in Morgans.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
To determine the origin of benign cystic teratomas of the ovary, chromosome-banding studies were done on normal tissues and teratomas from five patients. The normal tissues were heterozygous (+/-) for 17 chromosome polymorphisms at or near the centromere, whereas the teratomas were uniformly homozygous (+/+ or -/-). These findings and those employing electrophoretic variants indicate that ovarian teratomas are parthenogenic tumors that arise from a single germ cell after the first meiotic division.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
If benign cystic teratomas (dermoid cysts) of the ovary arise from a germ cell that has undergone meiosis, they should be missing genes which are present in the person. Three independently segregating allelic isozymes in 11 benign cystic teratomas of the human female ovary were compared with normal tissue of the same case. Dermoid cysts from persons heterozygous for these isozymes are frequently homozygous for that particular gene product. One of two dermoid cysts is homozygous for glucose-6-phosphate dehydrogenase, two of four tumors are homozygous for phosphoglucomutase at the PGM(1) locus, and two (or more) of eight tumors are homozygous for phosphoglucomutase at the PGM(3) locus in women heterozygous for these allelic isozymes. These findings are consistent with the hypothesis that these tumors arise from a germ cell which has undergone meiosis with varying degrees of crossing-over.
The sex-linked electrophoretic variants A and B of glucose-6-phosphate dehydrogenase were studied in 86 samples of myometrium and 27 leiomyomas from five heterozygous women. All but one sample of myometrium had both A and B bands in equal or nearly equal amounts. In contrast to this, all of the leiomyomas had either an A band or a B band. Both A and B tumors were found in all uteri. These findings are consistent with the hypothesis that these tumors arose from single cells.
The BATLE LE TCA-100 tumour chemosensitivity assay has been used to evaluate chemotherapeutic drug sensitivity of cultured tumour cell lines. Studies were performed using test drug concentrations calibrated to discriminate sensitivity and resistance of clinical specimens. Strong sensitivity which appeared to be inconsistent with clinical experience was detected for some drugs and cell lines. Findings of strong sensitivity were consistent with basic differences between sensitivity testing cultured cell lines and clinical specimens. Results with cell lines frequently may not apply directly to clinical applications. Characterization of differences between cell lines and clinical specimens may assist in application of cell line findings to clinical trials.
Human pancreatic carboxypeptidase A, which was isolated from a pool of necrobiotic pancreae, crystallized spontaneously and appeared homogenous in sodium dodecylsulphate polyacrylamide gel electrophoresis. Reversed phase high performance liquid chromatography of the dissolved crystals, however, revealed the presence of two distinct isoenzymes, which were shown by aminoterminal sequence analysis to be only 61% homologous in their 31 amino terminal amino acids. On the other hand, amino terminal sequences of the isoenzymes were found to be 79% and 87% homologous with CAP1 and CPA2 of the rat, respectively. Thus, the presence of two distinct pancreatic carboxypeptidase A isoenzymes could be clearly demonstrated for the first time in human tissue.
Purification of a soluble cytochrome c6 from the unicellular green alga Scenedesmus obliquus by a simple and rapid method is described. The purification procedure includes ammonium sulfate precipitation and non-denaturating PAGE. The N-terminal sequence of the first 20 amino acids was determined and shows 85% similarity and 75% identity to the sequence of cytochrome c6 from the green alga Monoraphidium braunii. The ferrocytochrome shows typical UV/VIS absorption peaks at 552.9, 521.9 and 415.7 nm. The apparent molecular mass was estimated to be 12 kDa by SDS-PAGE. EPR-spectroscopy at 20 K shows resonances indicative for two distinct low-spin heme forms.