Biography:

In the past Marian B. Meyers has collaborated on articles with Michael P. LaQuaglia. One of their most recent publications is Conformational changes in erythrocyte membranes by prostaglandins as measured by circular dichroism☆. Which was published in journal Archives of Biochemistry and Biophysics.

More information about Marian B. Meyers research including statistics on their citations can be found on their Copernicus Academic profile page.

Marian B. Meyers's Articles: (6)

Conformational changes in erythrocyte membranes by prostaglandins as measured by circular dichroism☆

AbstractMembranes were prepared from fresh, washed human erythrocytes by hemolysis and washing with 5 mm sodium phosphate buffer (pH 7.4). The mean residue ellipticity, [θ], of erythrocyte membrane circular dichroism was altered by prostaglandin E1 or prostaglandin F2α at 37 °C when observed from 250 nm to 190 nm. The decrease in negativity of [θ] with 10−6m prostaglandin E1 was 12.7% at 222 nm and 17.7% at 208 nm, and with 10−6m prostaglandin F2α 22.5% and 34.2%, respectively (P < 0.01). Similar changes in [θ] were observed at lower concentrations of prostaglandins. No strict relationship between amount of change of [θ] and prostaglandin concentrations of 3 × 10−5m to 3 × 10−12m was evident. A persistent alteration of [θ] with prostaglandin was observed at 37 °C. Transient change of [θ] occurred at 25 °C with prostaglandin. No change of [θ] was observed at 15 or 20 °C. Buffer or palmitic acid were without effect on membrane [θ]. Phosphatidyl inositol or methyl arachidonate caused an increase in negativity of membrane spectra. The observed alterations of membrane [θ] did not arise from changes in light scattering as the OD700–OD200 of membranes was not changed by prostaglandin. Effects of prostaglandin were not dependent on light path length. The prostaglandin E1 antagonist, 7-oxa-13-prostynoic acid, at 10−7m produced no change of [θ] of membrane spectra and prevented the otherwise demonstrable effects of 10−10m prostaglandin E1 on [θ]. The decrease in negativity of [θ] at 222 nm is indicative of a decrease in ellipticity of membrane protein. These studies suggest that prostaglandins may act by inducing a conformational change in membrane protein.

Increased synthesis of a low molecular weight protein in vincristine-resistant cells

AbstractA 19,000-dalton peptide (pI = 5.7) that is synthesized in increased amounts in vincristine-resistant Chinese hamster cells (DC-3FVCRd-5) has been identified by two-dimensional gel electrophoresis. Reduced amounts of the protein were present in a revertant line of DC-3FVCRd-5, and only trace amounts were detected in control DC-3F cells. A similar protein (Mr = 19,000; pI = 5.7) was also found in a vincristine-resistant mouse line. Two vincristine-resistant human neuroblastoma cell lines likewise contained elevated levels of a low molecular weight acidic protein. Increased biosynthesis of the 19,000-dalton polypeptide in DC-3FVCRd-5 cells coincides with the presence of a homogeneously staining region, HSR, on a metaphase chromosome.

Conformational changes in erythrocyte membranes by prostaglandins as measured by circular dichroism☆

AbstractMembranes were prepared from fresh, washed human erythrocytes by hemolysis and washing with 5 mm sodium phosphate buffer (pH 7.4). The mean residue ellipticity, [θ], of erythrocyte membrane circular dichroism was altered by prostaglandin E1 or prostaglandin F2α at 37 °C when observed from 250 nm to 190 nm. The decrease in negativity of [θ] with 10−6m prostaglandin E1 was 12.7% at 222 nm and 17.7% at 208 nm, and with 10−6m prostaglandin F2α 22.5% and 34.2%, respectively (P < 0.01). Similar changes in [θ] were observed at lower concentrations of prostaglandins. No strict relationship between amount of change of [θ] and prostaglandin concentrations of 3 × 10−5m to 3 × 10−12m was evident. A persistent alteration of [θ] with prostaglandin was observed at 37 °C. Transient change of [θ] occurred at 25 °C with prostaglandin. No change of [θ] was observed at 15 or 20 °C. Buffer or palmitic acid were without effect on membrane [θ]. Phosphatidyl inositol or methyl arachidonate caused an increase in negativity of membrane spectra. The observed alterations of membrane [θ] did not arise from changes in light scattering as the OD700–OD200 of membranes was not changed by prostaglandin. Effects of prostaglandin were not dependent on light path length. The prostaglandin E1 antagonist, 7-oxa-13-prostynoic acid, at 10−7m produced no change of [θ] of membrane spectra and prevented the otherwise demonstrable effects of 10−10m prostaglandin E1 on [θ]. The decrease in negativity of [θ] at 222 nm is indicative of a decrease in ellipticity of membrane protein. These studies suggest that prostaglandins may act by inducing a conformational change in membrane protein.

Conformational changes in erythrocyte membranes by prostaglandins as measured by circular dichroism☆

AbstractMembranes were prepared from fresh, washed human erythrocytes by hemolysis and washing with 5 mm sodium phosphate buffer (pH 7.4). The mean residue ellipticity, [θ], of erythrocyte membrane circular dichroism was altered by prostaglandin E1 or prostaglandin F2α at 37 °C when observed from 250 nm to 190 nm. The decrease in negativity of [θ] with 10−6m prostaglandin E1 was 12.7% at 222 nm and 17.7% at 208 nm, and with 10−6m prostaglandin F2α 22.5% and 34.2%, respectively (P < 0.01). Similar changes in [θ] were observed at lower concentrations of prostaglandins. No strict relationship between amount of change of [θ] and prostaglandin concentrations of 3 × 10−5m to 3 × 10−12m was evident. A persistent alteration of [θ] with prostaglandin was observed at 37 °C. Transient change of [θ] occurred at 25 °C with prostaglandin. No change of [θ] was observed at 15 or 20 °C. Buffer or palmitic acid were without effect on membrane [θ]. Phosphatidyl inositol or methyl arachidonate caused an increase in negativity of membrane spectra. The observed alterations of membrane [θ] did not arise from changes in light scattering as the OD700–OD200 of membranes was not changed by prostaglandin. Effects of prostaglandin were not dependent on light path length. The prostaglandin E1 antagonist, 7-oxa-13-prostynoic acid, at 10−7m produced no change of [θ] of membrane spectra and prevented the otherwise demonstrable effects of 10−10m prostaglandin E1 on [θ]. The decrease in negativity of [θ] at 222 nm is indicative of a decrease in ellipticity of membrane protein. These studies suggest that prostaglandins may act by inducing a conformational change in membrane protein.

Increased synthesis of a low molecular weight protein in vincristine-resistant cells

AbstractA 19,000-dalton peptide (pI = 5.7) that is synthesized in increased amounts in vincristine-resistant Chinese hamster cells (DC-3FVCRd-5) has been identified by two-dimensional gel electrophoresis. Reduced amounts of the protein were present in a revertant line of DC-3FVCRd-5, and only trace amounts were detected in control DC-3F cells. A similar protein (Mr = 19,000; pI = 5.7) was also found in a vincristine-resistant mouse line. Two vincristine-resistant human neuroblastoma cell lines likewise contained elevated levels of a low molecular weight acidic protein. Increased biosynthesis of the 19,000-dalton polypeptide in DC-3FVCRd-5 cells coincides with the presence of a homogeneously staining region, HSR, on a metaphase chromosome.

Multidrug resistance in human neuroblastoma cells☆☆☆

AbstractNeuroblastoma remains a significant problem in pediatric oncology. Recently a “multidrug-resistance” gene that may cause cells to become resistant to various chemotherapeutic agents has been cloned. The gene encodes the high-molecular-weight plasma membrane protein known as P-glycoprotein. To study the expression of this gene in cells exhibiting the multidrug-resistant phenotype, a panel of sublines selected with several different natural product drugs was established. The drug-sensitive parental BE(2)-C cells were clonally isolated from the human neuroblastoma SK-N-BE(2) line and exhibit a 150-fold increase in the copy number of the N-myc protooncogene. Sublines were selected by stepwise increases in the concentration of actinomycin-D, doxorubicin, vincristine, or colchicine. Gene amplification was assessed using Southern analysis, and RNA levels were determined by Northern and dot-blot analysis. Western blotting was used to determine protein levels. N-myc amplification and expression were simultaneously determined to assess possible alterations associated with development of multidrug resistance. Amplified P-glycoprotein-encoding genes were not seen in control lines but were clearly present in those that had undergone exposure to each of the chemical agents. Similarly, steady-state messenger RNA and protein levels were greatly increased in the drug-resistant sublines. We conclude that human neuroblastoma cells can acquire the multidrug-resistant phenotype after exposure to various chemotherapeutic agents.

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