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M Stöhr

Publications and source records attributed to M Stöhr.

131 records · Page 8Linked to original sources
PubMedDate not supplied

Observations on leukocytes from patients with severe familial hypercholesterolemia.

Differences in light scatter and fluorescence emission of blood leukocytes from patients with familial hypercholesterolemia (FH) and normal patients incubated with oil red O and r(NBD-Cl)-acetyl-LDL were observed by flow-through cytofluorometry and used to distinguish a subclass of leukocytes. The appearance of this subpopulation of leukocytes in FH apparently correlated with the excessive hypercholesterolemia. In addition, microscopic evaluation of blood smears suggested the formation of small cytoplasmic vacuoles in a population of FH monocytic cells. While these are preliminary observations on a small number of patients, they warrant further study. However, the use of lipophilic dyes and fluorescent acetyl-LDL in combination with flow cytometry may be another useful means for evaluation of FH.

Azo Compounds↗
PubMedDate not supplied

On the correlation of chromosome number and DNA content in HeLa cell clones.

Chromosome number and nuclear DNA content of two cloned HeLa cell lines were analysed by quantitative Feulgen reaction microspectrophotometry, ultra-rapid microfluorometry and chromosome counting. These cell clones revealed corresponding alterations in their chromosome number and nuclear DNA amount. The results support the hypothesis that a constant relationship exists between both chromosome number and nuclear DNA content in these clonal population.

Cell Count↗
PubMedDate not supplied

Reversing multidrug resistance in L1210 tumor cells by hycanthone or chlorophenoxamine in vitro and in vivo.

In the presence study we demonstrated that hycanthone and chlorophenoxamine can modulate the resistance of multidrug resistant (MDR) murine L1210 leukemia tumor lines in vitro and in vivo. The circumvention of MDR by hycanthone and chlorophenoxamine in vitro was demonstrated by a short-term test using tritiated nucleic acid precursors and by flow cytometrical measurement of accumulation of rhodamine 123. Furthermore, we treated mice bearing resistant L1210 ascites cells with doxorubicin and hycanthone or chlorophenoxamine. Hycanthone in combination with doxorubicin significantly inhibited tumor growth. We also found an improved therapeutic effect of doxorubicin plus chlorophenoxamine. Our results in vitro and in vivo indicate that hycanthone and chlorophenoxamine might be appropriate tools for the circumvention of MDR in human tumors.

Animals↗
PubMedDate not supplied

Dinaline inhibits amino acid transport and proliferation of colon carcinoma cells in vitro.

The human colon carcinoma cell line SW707 was incubated with different concentrations (7 microM - 540 microM) of the novel antineoplastic drug 4-amino-N(2'-aminophenyl)benzamide (GOE1734, dinaline) to study the effects on 3H-alpha-aminoisobutyric acid (AIB) - and 14C-methionine uptake as well as on 3H-thymidine incorporation into DNA. Additionally, adenine nucleotide pools were determined by high performance liquid chromatography (h.p.l.c.), and cell cycle distribution by flow cytometry. 24 h exposure to low concentrations of dinaline caused mild cell proliferation which turned into a cytostatic effect within a further 24 h without drug exposure. High concentrations of dinaline, however, were found to be cytostatic and then cytotoxic after corresponding time intervals. Dinaline caused a concentration-dependent decrease in sodium-dependent AIB uptake. Immediately after exposure the effect ranged from 67%-36% of control uptake. One day later an incomplete recovery not exceeding 70% of control was found for the three highest concentrations. This differed significantly from sodium-dependent methionine uptake which was initially decreased by 24%-36% but recovered within one hour and was enhanced one day after exposure. Significant differences were also measured for sodium-independent AIB uptake and sodium-independent methionine uptake immediately, 1 and 4 h after exposure. Adenine nucleotide pools were mildly increased immediately and 4 h after exposure. Thymidine incorporation into DNA was decreased by 70% to 84% immediately after exposure, and no full recovery was seen in the subsequent observation period. Cell cycle analyses revealed a block at the S phase entrance. Changes in thymidine incorporation and S phase fraction were highly correlated. The inhibition of the sodium-dependent uptake of AIB might indicate interaction of dinaline with cell membrane functions at low concentrations, the increase in methionine uptake points to enhanced protein synthesis following drug withdrawal and the impaired thymidine incorporation into DNA results from the cytostatic effect of dinaline. Taken together, the results show that SW707 colon carcinoma cells exposed to dinaline demonstrate distinct but reversible changes in amino acid transport, protein metabolism, DNA synthesis and cell proliferation, thus giving a correlation with observations in vivo.

Adenine Nucleotides↗