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Biomedical subjects

J Mordoh

Publications and source records attributed to J Mordoh.

At least 55 records · Page 3Linked to original sources
PubMed1985

A prostatic-like acid phosphatase is present in human lactating milk.

The presence of a prostatic-like acid phosphatase is reported in human lactating milk. Its activity is associated with skim milk and it could be separated from the other acid phosphatases only after Triton X-100 treatment. By all the criteria applied, it appears to be very similar to prostatic acid phosphatase. An approximate molecular weight of 96 000 was measured for the native enzyme, which is inhibited by L-(+)tartrate and has similar electrophoretic migration. Besides, it hydrolyzes choline-o-phosphate very well and cross-reacts with an antibody anti-prostatic acid phosphatase. This prostatic-like acid phosphatase has also been detected in a human mammary carcinoma from a lactating patient.

Acid Phosphatase↗
PubMed1984

Acid phosphatase in human breast cancer tissue.

When the total acid phosphatase (AP) activity of mammary carcinoma was compared with those of benign pathology and normal mammary tissue the results showed statistically significant differences (P less than 0.05) when expressed per milligram of protein: 358 +/- 42 nmoles per hour (mean +/- standard error) in the malignant tumor, 216 +/- 30 in the benign pathology, and 96 +/- 45 in normal tissue and when expressed per milligram of DNA: 1858 +/- 234, 1227 +/- 140, 695 +/- 345 nmoles per hour, respectively. The polyacrylamide gel electrophoretic profiles showed different levels of isoenzymes 3 and 4 in the three tissue groups. The appearance of isoenzyme 1 is reported after treatment of the homogenates with 5% Triton X-100. It was also found by counterimmunoelectrophoresis that the 28,000 Xg mammary tumor supernatant cross reacts with an antiserum raised against AP isoenzyme 2 although the mammary tissue does not contain such an isoenzyme. To elucidate this point, isoenzymes 1, 3 and 4 were separated by columns of Sephadex G-200 and DEAE-Sephadex. By counterimmunoelectrophoresis, it was observed that only the fraction containing isoenzyme 4 cross-reacted with the antiserum anti-AP isoenzyme 2 maintaining the catalytic activity.

Acid Phosphatase↗
PubMed1984

A high-molecular weight complex with acid phosphatase activity in human breast cancer.

The presence of a high-molecular weight complex with acid phosphatase activity in the cytosol of human mammary tumors is reported. This complex appeared in the cytosol after tissue homogenization in the presence of dithiotreitol, with or without Triton X-100 and at acidic or neutral pH. Upon gel electrophoresis, this fraction showed only one band of enzyme activity which did not enter the fine pore gel. Lubrol or n-butanol had no apparent effect on this complex, and 8 M urea or 2% sodium dodecyl sulfate did not disaggregate this large molecule. After purification by gel filtration, ammonium sulfate precipitation and ion-exchange chromatography an apparent molecular weight or 10(6) was measured. It hydrolyzed typical acid phosphatase substrates such as p-NPP and alpha-NP, but also ATP and PPi. Only 44% inhibition was observed with L-(+)tartrate and it was still 40% active after 1 hr incubation at 60 degrees C. Reduction in the presence of SDS yielded several polypeptide bands. It was also detected in some samples of normal mammary tissues, but not in normal human placenta or liver.

Acid Phosphatase↗
PubMed1984

Dipyridamole inhibits reversion by thymidine of methotrexate effect and increases drug uptake in Sarcoma 180 cells.

The combined effect of methotrexate (MTX) with dipyridamole, an inhibitor of nucleoside transport, was studied in ascitic Sarcoma 180 cells. It was determined that 10 microM MTX inhibits by greater than 90% deoxy[3H]uridine incorporation into DNA and that this MTX concentration inhibits DNA synthesis as revealed by deoxy[3H]cytidine but not [3H]thymidine incorporation into DNA. Exogenous thymidine (greater than or equal to 1 microM) in the cell culture medium enhances DNA synthesis in nontreated cells and fully restores it in MTX-treated cells, whereas hypoxanthine has no appreciable effect on DNA synthesis. Dipyridamole inhibits deoxy[3H]cytidine and [3H]thymidine uptake by these cells (IC50 = 0.2 and 3 microM, respectively) and blocks the increase in TTP pool produced by 1 microM thymidine in MTX-treated cells (23.1 +/- 4.7 pmol per 1 X 10(6) cells vs. 80.4 +/- 18.9 pmol per 1 X 10(6) cells). Dipyridamole at 10 microM enhances [3H]MTX accumulation by Sarcoma 180 cells and diminishes the efflux of the drug in previously loaded cells. It is suggested that the combination of inhibitors of the de novo pathway for pyrimidine biosynthesis, such as MTX, with inhibitors of the salvage pathway, such as dipyridamole, may increase the cytotoxic activity of MTX alone.

Animals↗
PubMed1983

Inhibitory effect of 1-beta-D-arabinofuranosylcytosine on the synthesis of phosphatidyl-dCMP.

The synthesis of phosphatidyl-dCMP in mouse thymocytes is inhibited by the antineoplastic agent 1-beta-D-arabinofuranosyl cytosine (AraCyt) 50% inhibition (ID50) being reached at an AraCyt concentration of 0.18 mM. In the same cells, ID50 for DNA synthesis is 0.03 mM. This inhibition is probably mediated by the phosphorylated derivative of AraCyt (aCTP) since the synthesis of phosphatidyl-dCMP from dCTP using permeabilized thymocytes is inhibited by aCTP (ID50 = 0.11 mM). The incorporation of [3H]AraCyt into the organic phase could also be detected, suggesting that this drug may act as a substrate for the enzyme that catalyzes the transfer of dCTP into phosphatidic acid.

Animals↗
PubMed1983

Separation of newborn BALB/c thymocytes by a density gradient method.

The recognition of T-lymphocyte subpopulations has led to a search for methods to separate lymphoid subsets on the basis of physical, biochemical and biological differences. The analysis of these properties of thymic cells made it possible to distinguish two main subsets: a major population of immunologically inactive cells, and a minor subpopulation of immunocompetent T cells. In the present paper a method for the separation of thymic lymphoid cell subpopulations in mice aged 5 to 10 days is reported. The cells resulting from this procedure were analyzed according to different criteria. From a morphological point of view, the existence of a large blast-like cell (termed I) and a smaller cell (termed III) was evident. These two cell subclasses were investigated in order to characterize their division rate, in vitro sensitivity to dexamethasone and peanut lectin agglutination pattern. It was found that subpopulation I had a faster division rate than subpopulation III, as measured in vitro by [3H]thymidine (dThd) incorporation and mitotic index with colchicine. When these different cells were incubated in the presence of dexamethasone at different concentrations, no significant difference was seen in [3H]dThd incorporation at the age of 5 days, while on the tenth day subpopulation I became more resistant to the hormone than subpopulation III. When incubated with peanut lectin, it was evident that subpopulation I was mainly constituted by PNA-unagglutinable cells. On the other hand, subpopulation III consisted mostly of PNA-agglutinable cells.

Aging↗
PubMed1981

Synthesis of phosphatidyl-dCMP in human lymphocytes and its enhancement by chlorpromazine.

When phytohemagglutinin-stimulated lymphocytes are labelled with [3H]deoxycytidine (dCyd), a compound soluble in organic solvents is formed. Several analytical procedures such as thin-layer chromatography and alkaline hydrolysis of the product obtained after labeling of stimulated lymphocytes with [14C]glycerol and [3H]dCyd, suggest that the product synthesized is phosphatidyl-dCMP. This compound is synthesized in much smaller amounts than when permeabilized lymphocytes and [3H]dCTP as a precursor are used. The synthesis of phosphatidyl-dCMP is highly enhanced by chlorpromazine, phosphatidic acid and arachidonic acid, whereas addition of inositol diminishes the amount of detected phosphatidyl-dCMP. It is suggested that this compound would be a precursor of phosphatidylinositol.

Chlorpromazine↗
PubMed1981

Isolation of tumor cells from patients with osteosarcoma and analysis of their sensitivity to methotrexate.

Many clinical studies have been conducted on the role of high-dose methotrexate (MTX) in human osteosarcoma, but information about the in vitro effect of MTX on human osteosarcoma cells is lacking. In this paper, the effect of MTX on tumor cells derived from seven patients with osteosarcoma has been studied in an attempt to correlate clinical and in vitro sensitivity to the drug. Isolation of the cells from the primary tumors (four patients) or metastasis (three patients) was carried out with a collagenase treatment followed by purification through a density gradient. The osteosarcoma cells were identified by electron microscopy and histochemical reactions. The cellular sensitivity to MTX was measured by the inhibitory effect of MTX on [3H]deoxyuridine incorporation into DNA. This incorporation ws 50% inhibited in primary tumors at concentrations from 3 X 10(-7) to 3 X 10(-6) M. The metastatic cells isolated from patients that were clinically resistant to high-dose MTX had a 50% inhibition ranging from 1.5 X 10(-7) to 4 X 10(-5) M. Human stimulated lymphocytes, Sarcoma 180 cells, and Ehrlich ascitic mouse cells had a 50% inhibition of about 1.5 X 10(-7) M. When [3H]thymidine incorporation into DNA of human osteosarcoma cells was studied, it was observed that MTX increased its incorporation up to 4-fold. This increase was stable for at lest 6 hr and was only slightly enhanced by the addition of hypoxanthine. The stimulation by MTX of [3H]thymidine incorporation into DNA in stimulated lymphocytes and Ehrlich cells is much smaller, between 40 and 60%. A hypothesis to explain these results is that osteosarcoma cells build their deoxythymidine monophosphate pool largely through the de novo pathway, the salvage pathway being less important. It is suggested that the importance of the de novo pathway for deoxythymidine monophosphate synthesis is a biochemical characteristic of the osteosarcoma cells which could be related to the initial sensitivity of this tumor to MTX and that an activation of the salvage pathway could constitute an additional mechanism of resistance to this drug.

Cell Separation↗
PubMed1979

Synthesis of phosphatidly-dCMP in permeabilized normal human lymphocytes.

When peripheral lymphocytes stimulated with phytohemagglutinin were permeabilized in vitro, (3H) dCTP acted as a precursor for DNA synthesis, but the formation of a compound soluble in organic solvents could also be demonstrated. The structure of the latter compound was studied analyzing the products formed after alkaline hydrolysis or an enzymatic treatment with nucleotide pyrophosphatase. Both treatments led to the formation of (3H)dCMP. When stimulated lymphocytes were labeled in vivo with (14C)glycerol before permeabilization and ulterior labeling with (3H)dCTP a double labeled compound was obtained. When this compound was submitted to alkaline hydrolysis, (3H)dCMP and (14C)glycerol-3-phosphate were obtained. It was concluded that the compound soluble in organic solvents was phosphatidyl-dCMP.

Cell Membrane Permeability↗
PubMed1977

Synthesis of a compound soluble in organic solvents from deoxycytidine triphosphate in permeabilized normal human lymphocytes.

Normal human lymphocytes may be rendered permeable to deoxynucleoside triphosphates. When [3H]dCTP is furnished to permeabilized lymphocytes tow compounds are formed: DNA and a compound soluble in organic solvents. [3H]dCTP incorporation is higher in stimulated lymphocytes than in unstimulated cells. Some characteristics of the system are reported.

Adenosine Triphosphate↗
PubMed1974

Synthesis of DNA in human lymphocytes: possible control mechanism.

Partially purified, isolated nuclei from lymphocytes either stimulated or not stimulated by phytohemagglutinin can equally well synthesize DNA when [(3)H]dTTP is used as precursor. Studies of DNA polymerase activity in nuclei and cytoplasm from these cells showed that the enzyme can be detected in either stimulated or nonstimulated lymphocytes. In nonstimulated lymphocytes the uptake of thymidine is very low. The use of inhibitors such as cycloheximide, arbinosylcytosine, and actinomycin D showed that a parallel existed between thymidine uptake and DNA synthesis. All the conditions in which DNA synthesis was inhibited resulted also in an inhibition of thymidine uptake.

Cell Fractionation↗