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L Marton

Publications and source records attributed to L Marton.

10 recordsLinked to original sources
PubMed1997

Effects of the polyamine analogues BE-4-4-4-4, BE-3-7-3, and BE-3-3-3 on the proliferation of three prostate cancer cell lines.

PURPOSE: Polyamines are biologic cations necessary for normal cell growth. Polyamine analogues have been shown to be effective inhibitors of tumor growth. We tested the effect of the polyamine analogues 1,1 9-bis(ethylamino)-5,10,15-triazanonadecane (BE-4-4-4-4), N1,N11-bis(ethyl)norspermine (BE-3-3-3) and 1,15-bis(ethylamino)-4,12-diazapentadecane (BE-3-7-3) on the growth of the prostate cancer cell lines DU145, LNCaP and PC-3 in vitro. We also tested the effect of BE-4-4-4-4 on androgen-independent DU145 cells in vivo via a nude mouse xenograft model. METHODS: In vitro, cell proliferation was measured using a DNA assay or a colony-formation assay. In vivo, mice were given saline or BE-4-4-4-4 3 mg/kg or 5 mg/kg intraperitoneally twice daily on days 7-10 and 14-17 (cycle 1), days 49-52 and 56-59 (cycle 2) and days 91-94 and 98-101 (cycle 3). RESULTS: The proliferation of DU145, LNCaP and PC-3 prostate cancer cell lines was inhibited in a dose-dependent manner by BE-4-4-4-4. Intracellular putrescine, spermidine and spermine levels in all three cell lines declined after only 24 h exposure to BE-4-4-4-4 in vitro. Animals receiving BE-4-4-4-4 showed inhibition of tumor growth which continued throughout the experiment with 74% (3 mg/kg) and 81% (5 mg/kg) growth inhibition seen on day 101. No overt toxic reactions besides weight loss were observed in BE-4-4-4-4-treated animals. Tumor tissue from animals treated with BE-4-4-4-4 showed a dose-dependent decrease in spermidine and spermine levels but no decline in putrescine levels as compared with control. BE-4-4-4-4 levels were highest in tumors on day 63 with levels reaching 0.33 and 1.45 nmol/mg protein from animals treated at the 3 mg/kg and 5 mg/kg doses, respectively. CONCLUSION: These results show the polyamine analogues BE-4-4-4-4, BE-3-3-3 and BE-3-7-3 to be effective inhibitors of prostate cancer cell growth in vitro and BE-4-4-4-4 to be an effective inhibitor of DU145 cells in vivo with minimal toxicity.

Animals↗
PubMed1997

Antisense expression of the peptide transport gene AtPTR2-B delays flowering and arrests seed development in transgenic Arabidopsis plants.

Previously, we identified a peptide transport gene, AtPTR2-B, from Arabidopsis thaliana that was constitutively expressed in all plant organs, suggesting an important physiological role in plant growth and development. To evaluate the function of this transporter, transgenic Arabidopsis plants were constructed expressing antisense or sense AtPTR2-B. Genomic Southern analysis indicated that four independent antisense and three independent sense AtPTR2-B transgenic lines were obtained, which was confirmed by analysis of the segregation of the kanamycin resistance gene carried on the T-DNA. RNA blot data showed that the endogenous AtPTR2-B mRNA levels were significantly reduced in transgenic leaves and flowers, but not in transgenic roots. Consistent with this reduction in endogenous AtPTR2-B mRNA levels, all four antisense lines and one sense line exhibited significant phenotypic changes, including late flowering and arrested seed development. These phenotypic changes could be explained by a defect in nitrogen nutrition due to the reduced peptide transport activity conferred by AtPTR2-B. These results suggest that AtPTR2-B may play a general role in plant nutrition. The AtPTR2-B gene was mapped to chromosome 2, which is closely linked to the restriction fragment length polymorphism marker m246.

Agrobacterium tumefaciens↗
PubMed1996

Preproricin expressed in Nicotiana tabacum cells in vitro is fully processed and biologically active.

Ricin, the highly toxic glycoprotein expressed in the endosperm of castor seeds, is composed of a galactose-binding lectin B chain (RTB) disulfide linked to a RNA N-glycosidase A chain (RTA). Chemically modified ricin has been conjugated to monoclonal antibodies and used for targeted therapy of cancer and autoimmune diseases. Replacement of chemically coupled molecules with a genetically engineered targeted ricin would improve homogeneity and yield and permit structural changes in the fusion toxin to be introduced readily by oligonucleotide-directed mutagenesis. Previous methods of expression of ricin fusion proteins have been limited to expression of RTA or RTB moieties alone or expression of incompletely processed toxin in Xenopus laevis oocytes. In the present study, we introduced the cDNA encoding preproricin into cultured tobacco cells via Agrobacterium tumefaciens-mediated gene transfer. Yields of ricin in soluble cell extracts were 1 microg/g in cells or, approximately, 0.1% of the total soluble protein. The ricin was partially purified by P2 monoclonal antibody anti-RTB affinity chromatography. The RTA and RTB immunoreactive material migrated on SDS-PAGE at 65 kDa under nonreducing conditions and at 32-35 kDa under reducing conditions. The tobacco ricin bound to immobilized asialofetuin as avidly as castor bean ricin, suggesting intact sugar binding. Tobacco ricin inhibited rabbit reticulocyte lysate protein translation similar to castor bean ricin (IC50 of 3 x 10(-12) M for tobacco ricin and 1 x 10(-11) M for castor bean ricin). The human cutaneous T cell lymphoma cell line HUT102 showed similar sensitivity to tobacco ricin when compared to castor bean ricin (IC50 = 9 x 10(-13) and 2 x 10(-12) M, respectively). The efficiency of gene transfer, reasonable levels of expression, and full post-translational processing indicate that this expression system is suitable for production of ricin fusion toxins for therapeutic applications.

Agrobacterium tumefaciens↗
PubMed1993

Alz-50 immunohistochemistry in the normal sheep striatum: a light and electron microscope study.

Alz-50 is a monoclonal antibody raised against ventral forebrain tissue from patients with Alzheimer's disease (AD). It was originally believed that the antigen recognized by Alz-50 was only found in degenerating neurons. However, recent studies indicate that Alz-50 stains neurons in a limited but specific distribution in normal brains throughout life. As the antigen recognized by Alz-50 in normal brains may give some insight into the AD degenerative process, we characterized Alz-50 staining in the normal ovine striatum using immunoblots and immunocytochemistry at the light and electron microscope levels. We then compared the Alz-50 staining pattern with those of NADPH diaphorase histochemistry and immunocytochemistry using antisera against several neuropeptides, Alzheimer-related proteins, and heat-shock proteins. Western blot analysis indicated that the epitope recognized by Alz-50 in the normal sheep brain is on the microtubule-associated protein tau, and preadsorbing Alz-50 with a peptide corresponding to the amino terminus of the tau molecule eliminated staining. Alz-50 labeled a single population of cells in the ovine striatum, the medium aspiny neurons. At the light microscope level, the granular staining pattern closely resembled Alz-50 immunoreactive neurons in the normal human striatum and in cells undergoing early degeneration in AD. Alz-50 immunoreactive neurons stained immunocytochemically with antisera against somatostatin, neuropeptide Y, and histochemically for NADPH diaphorase. These cells were morphologically characterized by smooth dendrites, elaborate local axonal plexuses, and indented nuclei with filamentous inclusions. Ultrastructurally, Alz-50 immunodecorated ribosomes and membranous structures (e.g. vesicles, endoplasmic reticulum), and many boutons which contained Alz-50-positive synaptic vesicles. None of the antisera against other Alzheimer-related proteins, including paired helical filament protein, ubiquitin, beta-amyloid protein, or heat-shock proteins specifically stained the population of cells labelled by Alz-50. Other tau antisera also did not specifically stain these cells. We conclude that Alz-50 recognizes an amino terminal epitope that is exposed on tau proteins within a single, discrete population of neurons in the normal sheep striatum. The presence of this epitope in a normal cell population raises the possibility that the early stages of AD degeneration may involve the activation of a normal cellular pathway that modifies the tau molecule.

Alzheimer Disease↗
PubMed1983

Neuropathy accompanying IgM lambda monoclonal gammopathy.

A set of observations made on a patient with IgM lambda monoclonal gammopathy and neuropathy implicate humoral immunity in the pathogenesis of the neuropathy. A sural nerve biopsy from the patient showed a characteristic increase in the width of the intraperiod lines. Deposits of mu-heavy chains and lambda-light chains were found in myelin sheaths of the nerve biopsy. Immunohistochemically, it was demonstrated that mu-heavy chains and lambda-light chains from the patient's serum bound to myelin sheaths of normal peripheral nerves and to a lesser extent to myelin sheaths in the central nervous system (CNS). By immunoblots it was demonstrated that mu-heavy chains and lambda-light chains from the patient's serum bound to myelin associated glycoprotein but to no other antigens from the peripheral and central nervous systems. gamma and alpha heavy chains and chi light chains from the patient's serum were also shown to bind to myelin-associated glycoprotein but not as distinctly as the mu and lambda chains. It is postulated that the monoclonal gammopathy may have arisen on the background of polyclonal autoimmune attack directed against myelin-associated glycoprotein.

Biopsy↗
PubMed1980

Determination of organic acids in biological fluids by ion chromatography: plasma lactate and pyruvate and urinary vanillylmandelic acid.

We describe the general aspects of ion chromatography and how on-line counted ion-exchange techniques can be utilized to determine pyruvic and lactic acids in plasma and vanillymandelic acid in urine. Pyruvate and lactate are extracted from deproteinized plasma by use of an ion-exclusion resin. After elution from the resin, the plasma extract is chromatographed on an anion-exchange column, with 0.66 mmol/L sodium bicarbonate as the mobile phase. The effluent is detected with an electrical conductivity cell. Vanillylmandelic acid is extracted from diluted urine by use of an anion-exchange resin. After elution from resin, the urine extract is chromatographed on an ion-exclusion column, followed by electrochemical detection. We evaluated the procedures for precision, linearity, analytical recovery, intefering substances, and correlation with an established procedure. the combination of a preliminary resin extraction, an ion chromatographic separation, and a conductivity or electrochemical detector results in rapid, specific methods that can be adapted for use in the clinical laboratory. Preliminary data for other organic acids are presented.

Carboxylic Acids↗