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Biomedical subjects

E Ralston

Publications and source records attributed to E Ralston.

48 records · Page 3Linked to original sources
PubMed1980

Lysophosphatidylcholine in liposomal membranes: enhanced permeability but little effect on transfer of a water-soluble fluorescent marker into human lymphocytes.

In an attempt to enhance delivery of liposome contents into cells, we tested the effect of lysophosphatidylcholine on transfer of the fluorescent dye, carboxyfluorescein, from small unilamellar and large multilamellar vesicles to human lymphocytes. Dioleoyl phosphatidylcholine and dioleoyl phosphatidylcholine-lysophosphatidylcholine small unilamellar vesicles with varying lipid ratios were prepared and characterized. In the presence of lysophosphatidylcholine, small unilamellar vesicles were slightly smaller and more leaky than those made without lysophosphatidylcholine. Lysophosphatidylcholine induced less leakage in large multilamellar vesicles. It did not show any appreciable effect on transfer of liposome contents, whether included as part of the liposomal bilayer (of unilamellar or multilamellar vesicles) or added exogenously together with small unilamellar dioleoyl phosphatidylcholine vesicles.

Cell Membrane Permeability↗
PubMed1979

Effects of D and L amino acid residues in linear peptides on carbon-13 nuclear magnetic resonance parameters.

The 13C spectra of the linear tripeptidyl diastereoisomers, Gly-Gly-Leu, Gly-Gly-D-Leu, Leu-Gly-Gly, D-Leu-Gly-Gly, Ala3, Ala-Ala-D-Ala, Ala-D-Ala-Ala, Val3, and Val-Val-D-Val are very similar or even identical at pH meter readings of 1.0, 7.0 and 12.0 in D2O. The spectra of Pro-Leu-Gly-NH2 and Pro-D-Leu-Gly-NH2 likewise show only minor differences in 13C chemical shifts (less than 0.4 p.p.m.) under similar conditions. This contrasts significantly with previous findings comparing 13C chemical shifts of cyclo(Pro-Leu) and cyclo(Pro-D-Leu) where major differences in chemical shifts were observed for both residues due to differences in conformational constraints present in these cyclic proline-containing peptides. The least-squares fit of spin-lattice relaxation times (T1) for Pro-Leu-Gly-NH2 and Pro-D-Leu-Gly-NH2 show that it is not possible to fit all the T1 values to a unique and rigid structure whether folded or extended. The glycyl residue undergoes enhanced motion when compared with the prolyl and leucyl residues. Internal motion must be postulated within the proline ring and for the CH3 groups of leucine.

Amino Acid Sequence↗
PubMed1974

Tertiary structure of H-Pro-Leu-Gly-NH2, the factor that inhibits release of melanocyte stimulating hormone, derived by conformational energy calculations.

Conformational energy calculations were carried out on H-Pro-Leu-Gly-NH(2), the factor that inhibits the release of melanocyte stimulating hormone, and its biologically active analog, H-Pro-Ala-Gly-NH(2). Both peptides were found to be relatively compact molecules that retain, however, some degree of flexibility. After structure refinement, H-Pro-Leu-Gly-NH(2) possesses at least three preferred compact conformations. Two of these conformations occupy rather broad and flat energy troughs, while a third occupies a narrow and deep potential energy well. This third structure, which consists of a 10-membered beta-turn closed by a (4 --> 1) hydrogen bond between the proton of the trans carboxamide of Gly and the C=O of Pro, is the one that was proposed for H-Pro-Leu-Gly-NH(2) in dimethylsulfoxide and was also found by x-ray analysis.

Melanocyte-Stimulating Hormones↗
PubMed1972

Deoxyribonucleic acid homologies of some so-called "Hydrogenomonas" species.

Evidence based on deoxyribonucleic acid homology supports the abandonment of the genus Hydrogenomonas. Pseudomonas facilis (formerly Hydrogenomonas facilis) is closely related to the nonautotrophic species P. delafieldii. P. facilis and Alcaligenes eutrophus (often called H. eutropha) are not related to each other or to other hydrogen bacteria and pseudomonads studied.

Alcaligenes↗
PubMed1972

Deoxyribonucleic acid homologies among some Pseudomonas species.

Phylogenetic relationships among a number of strains belonging to the genus Pseudomonas were explored by the use of in vitro deoxyribonucleic acid (DNA) hybridization. The fluorescent nomenspecies (P. fluorescens, P. putida, P. aeruginosa, P. cichorii, P. syringae, and related species), as well as the nonfluorescent species P. stutzeri, P. mendocina, P. alcaligenes, and P. pseudoalcaligenes, were shown to belong to a single DNA homology complex which is isolated from other Pseudomonas species that have been studied [P. cepacia (= P. multivorans), P. caryophylli, P. marginata (= P. alliicola), P. pseudomallei, P. acidovorans, P. testosteroni, P. solanacearum, P. diminuta, P. facilis, P. delafieldii, P. saccharophila, P. palleronii]. A limited numerical analysis of the phenotypic properties of the examined strains supported, with some exceptions, their previous allocation to nomenspecies and biotypes. The internal structure and nomenclature of the "P. fluorescens homology complex" are discussed.

Biological Evolution↗
PubMedDate not supplied

Physicians' attitudes and beliefs about deaf patients.

BACKGROUND: We wanted to validate reports that deaf persons have difficulty obtaining medical care by comparing physicians' attitudes towards these patients with physicians' attitudes toward their patients in general. METHODS: Two questionnaires were randomly distributed to physicians attending continuing medical education conferences at the University of Michigan during a 3-month period. The questionnaires were identical except that one asked about deaf patients and the other about patients in general. The questions assessed the respondent's perceptions of communication with patients, attitudes toward their patients, knowledge of current information about deaf people, and demographics. RESULTS: One hundred sixty-five physicians responded, 94 to the general questionnaire and 71 to the deaf questionnaire. The two physician groups were similar demographically, but 165 differed significantly in communication and attitude variables. Physicians receiving the questionnaire focusing on deaf patients reported greater difficulties in understanding (P < 0.001) and maintaining free-flowing conversations (P < 0.001), and that these patients had more difficulty understanding them (P < 0.001), trusted them less (P < 0.001), asked them to repeat statements more often (P < 0.001) and were less likely to understand the diagnosis and recommended treatments (P < 0.001). Physicians also reported feeling less comfortable with deaf patients (P < 0.001) and that they asked fewer questions (P < 0.001). Physicians were more likely to say that deaf patients rely on interpreters (P = 0.040), get frustrated easily (P < 0.001), and are harder to communicate with (P < 0.001). There were no significant differences between the two groups in knowledge about deaf people. All physicians, however, displayed ignorance about their legal obligations under the Americans with Disabilities Act to provide interpreters for their deaf patients. CONCLUSIONS: Physicians surveyed about deaf patients reported significantly greater difficulties communicating with and different attitudes toward these patients than physicians surveyed about their patients in general. All physicians were unaware of their obligations under the Americans with Disabilities Act to provide interpreters for deaf patients. Research is needed to determine whether physician attitudes and beliefs affect the actual quality of care they deliver to deaf patients.

Adult↗