Search PubMed⌕ Search

Biomedical subjects

M Kohler

Publications and source records attributed to M Kohler.

96 records · Page 6Linked to original sources
PubMedDate not supplied

A quantitative study of normal nephrogenesis in the human fetus: its implication in the natural history of kidney changes due to low obstructive uropathies.

An evaluation of nephrogenesis according to fetal age was performed by quantifying the state of the nephrogenic blastema (NB) and the number of glomeruli (GN) on frontal renal sections in 99 control fetuses (gestational age ranging from 9 to 40 weeks) and in 17 aborted fetuses with low urinary tract obstruction (gestational age ranging from 14 to 36 weeks). In the control group, GN increases slowly from the 10th to the 18th week, then abruptly from the 18th to the 32nd week, reaching an upper limit with NB disappearance by the 32nd week. In the uropathy group, the renal changes show a wide range of severity clearly accounted for by the impairment of both NB and GN. The dysplastic effect of urinary backpressure is the more consistent pathogeny with the spectrum of observed renal changes. It is likely, from GN used as a time-dependent marker of renal development, that the most severe dysplasia is the result of early obstruction with abnormal disappearance of NB and subsequent arrest of nephrogenesis.

Female↗
PubMedDate not supplied

Ito cell tumor: immunohistochemical investigations of a rare lesion in the liver of mice.

In 2 lifespan transgeneration experiments using a total of 4,682 CBA/J mice, we observed uncommon lipomatous lesions in the livers of 8 mice independent of the treatment. Macroscopically, the lesions were described as pale white areas (2) or nodules (6) during necropsy. The lesions ranged from 1 to 15 mm in diameter. Microscopically, the lesions consisted of nodular aggregations of round to spindle-shaped cells that partly caused distinct compression of the adjacent hepatic parenchyma. The tumor cells were smaller than hepatocytes and had dark oval nuclei. Many of the more spherical cells contained clear vacuoles of various sizes, which were shown to be lipid droplets by oil red O staining. In addition to Gomori's silver and Masson's trichrome staining, several immunohistochemical stains were used to characterize the origin of the proliferating cells. Tumor cells were labeled by vimentin, actin, desmin, and proliferating cell nuclear antigen. The 2 cell phenotypes showed similar staining characteristics. Increased amounts of laminin and tenascin, 2 extracellular matrix proteins of the liver, were detected within these neoplasms. Summarizing, we suggest that these tumors are of Ito cell origin.

Adenocarcinoma↗
PubMedDate not supplied

Expression analysis of EGF-R and TGFa in human ovarian carcinomas.

Differences in the tumor biology of ovarian carcinomas probably influence operability and response to chemotherapy which are the most relevant prognostic factors. The phenotype of different malignant epithelial tumors including ovarian carcinomas is obviously associated with an activation of the EGF/TGFa signal pathway. When we analysed the expression of EGF-R and TGFa with biochemical, molecular-chemical and immunohistochemical methods in 29 different ovarian carcinomas, we found a correlation between the mRNA and protein levels of EGF-R as well as TGFa for tumors with low or high expressing rates. However, the concentration of measurable free EGF-Rs seems to depend on the amount of TGFa expression by the tumors. The EGF-R binding ligand TGFa is produced by the tumor cells; stromal cells are TGFa negative as shown by immunohistochemistry. By the use of an immunostaining index the TGFa protein concentration was measured semiquantitatively, classifying tumors according to their TGFa production rate. The comparison of TGFa mRNA amounts and staining index supports the hypothesis that TGFa is modified posttranslationally. EGF-R or TGFa expressing ovarian carcinomas had a high response rate to chemotherapy, whereas the EGF-R or TGFa negative tumors mostly exhibit a no change or progressive disease behaviour. These findings are the basis for our assumption that ovarian carcinomas with the basis for our assumption that ovarian carcinomas with an activated EGF-TGFa system are tumor biologically different compared to the EGF-R/TGFa negative tumors.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

The expression of EGF receptors, EGF-like factors and c-myc in ovarian and cervical carcinomas and their potential clinical significance.

The expression of the epidermal growth factor receptor (EGF-R) and the c-myc oncogene was investigated in different specimens of ovarian and cervical carcinomas. The EGF-Rs were analyzed by EGF binding assay, immunohistochemistry and Northern blotting. For analysis of c-myc expression, we used Northern blotting and immunohistochemistry. Furthermore, tissue concentrations of EGF-like factors (EGF-F) were measured in the same tumor and non-malignant specimens. The biochemical determination of EGF-R demonstrated that EGF specific binding sites were detected in 36% of ovarian (n = 140) and 81% of cervical carcinomas (n = 42). High amounts of EGF-R (greater than 10 fmol/mg specific binding) were found in 8% of the ovarian and 41% of the cervical carcinomas. Increased expression of EGF-R specific mRNA was detectable in 7/21 ovarian and in 5/7 cervical carcinomas. A positive correlation between the amounts of EGF-R mRNA, the EGF-R binding data and the staining index of EGF-R immunohistochemistry was found. The EGF-R immunohistochemistry demonstrates that only the tumor cells produce increased amounts of EGF-R, while the stromal cells are EGF-R negative. Low amounts of EGF-R specific mRNA were also detected in biochemically EGF-R negative tumors. The c-myc specific mRNA signal was found in all cases investigated. It is shown that the c-myc expression was increased in 10/21 ovarian and 5/7 cervical carcinomas. There was no positive correlation between the amounts of EGF-R and c-myc mRNAs. The product of myc, as detected by immunohistochemistry, is found in tumor as well as in stromal cells. The levels of EGF-F were measured in extracts of 63 ovarian and 12 cervical carcinomas and in 21 non-malignant tissues. About 30% of the tumor extracts contained higher EGF-F levels (4-15 ng/mg) than those found in the non-malignant specimens. Tumors with high EGF-F levels expressed high amounts of c-myc RNA. The EGF-R status (n = 111) and the EGF-F levels (n = 63) were related to the prognosis of survival for patients with ovarian carcinomas. EGF-R positive (EGF-R(+)) ovarian carcinomas had a significantly higher response rate to chemotherapy. The survival time of the EGF-R(+) group is reduced compared to the EGF-R negative (EGF-R(-)) group if only patients in remission are used to construct survival curves. Furthermore, a poor prognosis for survival was noticed for ovarian carcinoma patients with high EGF-F levels.

Biomarkers, Tumor↗