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J Snider

Publications and source records attributed to J Snider.

26 records · Page 2Linked to original sources
PubMed1992

Characterization of the heterogeneity of polyethylene glycol-modified superoxide dismutase by chromatographic and electrophoretic techniques.

Covalent attachment of polyethylene glycol (PEG) chains to the enzyme Cu,Zn-superoxide dismutase (SOD) produces a heterogeneous mixture of modified protein species. The heterogeneity of the product (PEG-SOD) derives from a variable stoichiometric combination of PEG with individual SOD molecules in addition to the polydispersity of the PEG reagent. Characterization of PEG-SOD presents significant challenges due in part to this heterogeneity in addition to the hybrid nature of the modified enzyme. The application of classical methods of protein characterization is not always successful for these PEG-proteins requiring the development of alternative or modified procedures. A series of chromatographic techniques including reversed-phase, ion-exchange, size-exclusion, and hydrophobic interaction high-performance liquid chromatography along with electrophoretic techniques including isoelectric focusing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and capillary zone electrophoresis have been developed for assessing the degree of heterogeneity of PEG-SOD samples which encompass a range of different stoichiometries. Examples will be given demonstrating the application of these techniques to characterize PEG-SOD samples of different composition produced during the course of the reaction between SOD and an activated PEG reagent.

Animals↗
PubMed1990

Possible role of H1 histone in the differentiation of mouse erythroleukemia cells.

Serum-starved mouse erythroleukemia cells, stationary phase cells or cells cultured in dibutyryl cAMP (1 mM) can be induced to differentiate by addition of 20% fetal calf serum plus cycloheximide. Culturing unstarved log phase cells in 20% fetal calf serum plus low levels of cycloheximide and histone H1 also causes a significant level of differentiation. These same concentrations of cycloheximide and H1 histone employed separately with 20% fetal calf serum do not induce differentiation. The role these procedures may have in causing an accumulation of histone H1 and cell differentiation is discussed.

Animals↗
PubMedDate not supplied

A rapid microprocedure for isolating RNA from multiple samples of human and rat brain.

In order to establish a routine procedure for isolating undegraded RNA from small amounts of rat and human brain tissue, several techniques were investigated. Initial studies demonstrated that undegraded RNA could not be reproducibly isolated from milligram amounts of brain tissue homogenized in an aqueous medium. Several isolation techniques utilizing tissue homogenization in the denaturing agent guanidinium chloride were compared. This method of homogenization, followed by sedimentation of RNA through cesium chloride, resulted in good yields of undegraded translationally active RNA. A maximum of 6 RNA samples could be processed simultaneously. In contrast, when homogenization in guanidinium chloride was followed by repeated guanidinium chloride-ethanol precipitations many samples could be processed simultaneously. The resulting RNA yields were low. The introduction of several modifications in the guanidinium chloride-ethanol precipitation technique resulted in a high yield of undegraded translationally active RNA. DNA was removed by two guanidinium-ethanol precipitations. Residual protein was digested with proteinase K. RNA was precipitated after extraction with phenol-chloroform-isoamyl alcohol. This refined procedure allows the recovery, in high yields, of translationally active undegraded RNA which is both DNA and protein free. Thirty-six samples can be processed in one day.

Animals↗
PubMedDate not supplied

How does service drive the service company?

"How Does Service Drive the Service Company?" presents commentators on Leonard A. Schlesinger and James L. Heskett's September-October article. Commentators include Michael R. Quinlan, Ron Zemke, Jim Snider, Dinah Nemeroff, Steven S. Reinemund, Robert Ayling, Karmjit Singh, James A. Perkins, Joseph E. Antonini, and Walter F. Loeb.

Advertising↗
PubMedDate not supplied

Factors important in promoting cervical cancer screening among Canadian women: findings from the 1996-97 National Population Health Survey (NPHS).

Although routine Pap screening represents an effective tool in the early detection of cervical cancer, it remains underused by some Canadian women. This study examines selected sociodemographic, health, lifestyle, and system barriers to Pap test participation among 33,817 women aged 18+ years in the cross-sectional 1996-97 National Population Health Survey (NPHS). Among women 18 years and over, 87% reported ever having had a Pap test while 72% reported a recent (< 3 years) test. A report of ever and recent use was most common among women 25-34 (92% and 86.9%, respectively). Only 0.6% of recently screened women reported access problems. Among those without a recent test, most (53%) reported that they did not think it was necessary. Pap test use varied little across provinces and was less common among older and single women, those with lower education, a spoken language other than English, a birth place outside Canada and negative health and lifestyle characteristics.

Adolescent↗