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Biomedical subjects

R Wagner

Publications and source records attributed to R Wagner.

At least 469 records · Page 26Linked to original sources
PubMed1982

The relation between tumor cell proliferation and vascularization in differentiated and undifferentiated colon carcinomas in the rat.

Tumor cell proliferation and tumor vascularization were investigated in differentiated and undifferentiated colon carcinomas of the rat. The following results were found: 1, in both tumor types, vascularization is developed equally well; 2, both in the differentiated and in the undifferentiated carcinomas, the number of proliferating tumor cells decreases with increasing distance from the capillaries; at a distance of about 80 microns, there is no longer any noteworthy tumor cell proliferation; 3, the differentiated and undifferentiated carcinomas differ both in the level of the mitosis index and 3H-thymidine labeling index as well as in their local proliferation pattern despite equal vascularization; 4, these differences must be based on factors which are independent of vascularization; they are attributed to proliferation properties which are inherent in the differently differentiated tumor cell populations. It is concluded from this that the actual proliferation behavior of a carcinoma is primarily dependent on the proliferation properties of the tumor cell population.

Animals↗
PubMed1982

Chromosomal rearrangement and carcinogenesis.

All carcinogens that have been thoroughly tested have been found to induce some kind of chromosomal rearrangement. Chromosomal rearrangements are associated with a variety of human and rodent cancers and are associated, with in vitro cell transformation. The DNA from non-malignant cells can transform other non-malignant cells under conditions that may involve chromosomal rearrangement. These findings support the view that chromosomal rearrangement can be a step in carcinogenesis. Available evidence indicates that carcinogens can act to induce chromosomal rearrangement by creating or revealing sites on DNA for recombination, or by inducing or activating cellular systems resulting in a stimulation of recombination. Chromosomal rearrangement may affect carcinogenesis by altering gene expression. Perhaps by allowing the activation of cellular cancer genes.

Carcinogens↗
PubMed1982

Quantification of antigens with haemolysing antibodies exemplified by the bovine J blood group system.

1. The J blood group activity of red cells is measured in terms of 50% haemolysis ('direct test'), that of dissolved or suspended samples in terms of 50% haemolysis inhibition ('indirect test') in a standardized bovine J system. 2. The volume of J-containing sample required for a 50% haemolysis inhibition decreases with increasing J activity. 3. The volume of anti-J required for a 50% haemolysis of J-positive erythrocytes also decreases with increasing J activity. 4. The use of antigen units (UAg) was introduced to serve as a measure of J activity of dissolved or suspended samples. 5. Antigen units were also used to characterize J-containing red cells. This was made possible by measuring the relation of the direct test (on red cells). Thus, a relatively simple method of determination of red cell UAg is obtained. 6. It was confirmed by absorption experiments that erythrocytes containing high concentrations of antigen require relatively low amounts of antibody to bring about a 50% haemolysis, but are able to bind a relatively high excess of antibody.

Absorption↗
PubMed1982

Partition coefficients of 5-(substituted benzyl)-2,4-diaminopyrimidines.

The pK-values of 19 and the partition coefficients P of 79 5-benzyl-2,4-diaminopyrimidines substituted in the benzene moiety were experimentally determined. The results of a multiple regression analysis show that the partition coefficients cannot be calculated with reasonable accuracy starting from fragmental constants. Interactions between substituents can reduce P-values by an order of magnitude below those obtained by applying Hansch's and Rekker's models. Interaction terms between different substituents were calculated. Similar effects are to be expected for other poly-substituted aromatic compounds.

Chemical Phenomena↗
PubMed1981

Glucocorticoid receptor activation and inactivation in cultured human lymphocytes.

Although glucocorticoids are not cytolytic for and do not inhibit the growth of the IM-9 line of cultured human lymphoblasts, these cells have a high steroid-binding capacity. We have used IM-9 cells in order to examine whether unoccupied glucocorticoid receptors are inactivated and activated in intact cells. when IM-9 cells are incubated in glucose-free medium in a nitrogen atmosphere, both their ability to bind triamcinolone acetonide and their ATP levels decline and, when glucose and oxygen are reintroduced, ATP levels and receptor activity return. The specific glucocorticoid-binding activity of cytosol prepared from cells exposed to various degrees of energy limitation is directly correlated with the ATP content. Receptor activation in intact cells is rapid and independent of protein synthesis. Cytosol prepared from inactivated cells cannot be activated by addition of ATP. The inactivation of glucocorticoid receptors that occurs when cytosol from normal IM-9 cells is incubated at 25 degrees C is inhibited by molybdate, vanadate, fluoride, ATP, and several other nucleotides. The experiments with intact human lymphoblasts suggest that assays of specific glucocorticoid-binding capacity do not necessarily reflect the cellular content of receptor protein.

Adenosine Triphosphate↗
PubMed1981

N-Methyl-N'-nitro-N-nitrosoguanidine sensitivity of E. coli mutants deficient in DNA methylation and mismatch repair.

E. coli mutants deficient in DNA methylation (dam) and mismatch repair (mut) have been characterized with respect to their sensitivity to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Dam bacteria are more sensitive than mutH, mutL, and mutS single mutant bacteria. Dam mutL and dam mutS double mutant bacteria are less sensitive than dam bacteria, whereas dam mutH double mutant bacteria are as sensitive as dam bacteria. This pattern of MNNG sensitivity may be a result of the specificity of the components of the E. coli mismatch repair system.

DNA (Cytosine-5-)-Methyltransferases↗
PubMed1981

Malignant fibrous histiocytoma of the renal capsule.

We report about an extremely rare case of malignant fibrous histiocytoma (MFH) of the renal capsule. The tumor is composed of fibroblast-like cells arranged in a storiform pattern and histiocyte-like cells with multinucleated giant cells, both showing no iron reaction. Characteristic of the histiocytic quality of the tumor are numerous PAS-positive intracytoplasmic droplets which can be identified as erythrophagosomes only under the electron microscope. Emphasis is put on the preoperative differential diagnosis of the tumor from renal cell carcinoma as well as on its histogenesis and prognosis.

Aged↗
PubMed1981

Behavioral and biological effects of acute beta-endorphin injection in schizophrenic and depressed patients.

In this double-blind study, beta-endorphin, 4-15 mg, was administered intravenously to 6 schizophrenic and 4 depressed patients. There were neither significant differences in behavioral ratings between beta-endorphin and placebo for the overall group nor for either the schizophrenic or depressed subgroup. Clinical worsening and improvement were observed in individual schizophrenic patients. There was no evidence of late-appearing therapeutic effects in 4 schizophrenic patients rated for 5 consecutive days after placebo and drug infusions. In 1 patient 10 mg of beta-endorphin produced neuroendocrine effects comparable to those produced by 5 mg of intravenously administered methadone; in 2 other patients it produced large increases in circulating opioid activity as determined by radioreceptor assay. These biological data support the notion that parenterally administered beta-endorphin exerts significant opiate-like activity in vivo.

Adult↗
PubMed1981

Does uremic enterocolitis exist? A morphological and functional investigation of rat intestine in chronic renal insufficiency.

In rats a severe but compensated chronic renal insufficiency was induced by stepwise 9/10 nephrectomy. Despite this severe chronic renal insufficiency we observed no relevant pathological changes in the intestinal mucosa. In particular, we found no evidence of mucosal erosions, ulceration or pseudomembranous colitis, findings which are traditionally thought to be characteristic of the uremic state. This was also true of those animals dying prematurely from uremia. Thus serious doubts arise about the existence of "uremic enterocolitis", doubts which also proved justified after a critical review of the literature on human pathology.

Animals↗
PubMed1981

[Chronic intestinal ischemia after migration of larvae in ascaridiasis (author's transl)].

A case report is given of a 25 year old turkish patient, who had ascaridiasis and multiple stenoses of the small intestine. This syndrome was caused by extensive obliterating phlebitis of the small mesenterial veins and sclerosing lymphadenitis of the mesenterial lymph nodes. Granuloma containing epitheloid cells and giant cells could be found in the venous walls and in the lymph nodes, some of the granuloma being grouped around atrophic ascarides larvae; this demonstrates, that the intestinal stenoses represent an unusual complication of larvae migration in this worm disease. Perforation of the intestinal wall in one these stenotic areas possibly was caused by ascarides worms actively.

Adult↗
PubMed1980

[Ischemic lesions and post-ischemic regeneration of the small intestinal mucosa].

After ligationof the vascular arcades of the upper jejunum in rats ischemic damage to the intestinal mucosa and its regenerative behavior were investigated by histology, morphometry, enzyme-histochemistrym, autoradiography and electron microscopy. The process of ischemic damage begins at the tips of the villi and progresses to the crypts. After ischemia lasting 300 min the mucosa, submucosa and muscularis propria are necrotic, which means, that the small intestine is at this time completely infarcted. Whilst sthe ischemic damage to the crypt epithelia is similar to that of other kinds of epithelia, the ischemic damage to the enterocytes is different. The enterocytes are shed to the intestinal lumen without any signs of irreversible damage by a blebformation at their cell base. After 2 h ischemia -- the basal epithelia of the crypts are not irreversible damaged yet at this time--and a 12 h period of restored blood flow, the mucosal surface is completely covered again by a flat epithelium. This is achieved 1) by an above-normal proliferation of the epithelia derived from the residual crypts, 2) by the appearance of flat epithelia with an increased diameter. After 8 days of repair the small intestinal mucosa shows morphologically, autoradiographically and enzyme-histochemically a normal picture again.

Acid Phosphatase↗
PubMed1980

Gas chromatography mass spectrometry computer analysis of volatile halogenated hydrocarbons in man and his environment--A multimedia environmental study.

As part of a study to make a comparative analysis of selected halogenated compounds in man and the environmental media, a quantitative gas chromatography mass spectrometric analysis of the levels of the halogenated compounds found in the breath, blood and urine of an exposed population (Old Love Canal area, Niagara, New York) and their immediate environment (air and water) was undertaken. In addition, levels of halogenated hydrocarbons in air samples taken in the general Buffalo, Niagara Falls area were determined.

Air Pollutants↗