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Biomedical subjects

I M Asher

Publications and source records attributed to I M Asher.

13 recordsLinked to original sources
PubMed1984

Retropharyngeal abscess: a previously unreported symptom.

Four cases of retropharyngeal abscess are presented. All patients were older than the usual age group and all complained of pain in the back of the neck or shoulder precipitated or aggravated by swallowing. All recovered. The clinical features of retropharyngeal abscess are discussed, and the possible importance of this previously undescribed symptom in distinguishing retropharyngeal abscess from other less serious disease entities is proposed.

Abscess↗
PubMed1980

Cyclo(L-prolylglycyl)3 and its sodium, potassium, and calcium ion complexes: a Raman spectroscopic study.

Raman spectra of the cyclic hexapeptide cyclo-(L-prolylglycyl)3 and its Na+, K+, and Ca2+ complexes are reported for the solid state and for samples in solution. Model compounds and N-deuteration were used to aid mode identification. Spectra of the uncomplexed ionophore in solution are consistent with previously proposed solution conformations and permit the identification of spectral lines characteristic of proline-containing peptide bonds in the trans and the cis conformations. Upon cation complexation the prolyl carbonyl stretch bands sharpen and upshift 20-30 cm-1 (to 1690-1700 cm-1). The glycyl carbonyl stretch band is unaffected by Na+ complexation, upshifted approximately 15 cm-1 by K+ complexation, and downshifted approximately 20 cm-1 (to 1619 cm-1) by Ca2+ complexation. Arguments supporting the involvement of prolyl carbonyl groups in cation complexation are noted. Spectra of the Na+ complex of the tetramer cyclo(L-prolylglycyl)4 suggest an asymmetric structure.

Calcium↗
PubMed1975

Laser raman spectroscopy--new probe of myosin substructure.

Laser Raman spectroscopy is used to probe the heterogeneous substructure of the large contractile protein myosin. Some peaks are assigned to specific chemical groups of the molecule; others, notably the conformationally sensitive amide III vibrations, provide information on the structurally distinct regions of the molecule. Deuteration of the NH groups is instrumental in the assignment of these vibrational modes. The relative intensities of bands typical of alpha-helical conformations (near 1265 and 1304 cm-1) and bands associated with nonhelical structure (near 1244 cm-1) are sensitive indicators of myosin substructure and represent potentially useful probes of conformational changes.

Animals↗
PubMed1973

Raman spectroscopic evidence for two conformations of uncomplexed valinomycin in the solid state.

Raman spectroscopy is applied for the first time to elucidate the different conformations of the carrier transport molecule, valinomycin. Splitting of the ester and amide carbonyl stretch vibrations is observed in the Raman spectrum of crystals of valinomycin grown from both n-octane and acetone. These observations support the contention that some ester carbonyl groups are intramolecularly hydrogen bonded. The Raman spectrum of valinomycin grown from o-dichlorobenzene does not display this feature.

Acetone↗
PubMed1971

Histochemical fluorescence of raphe neurons: selective enhancement by tryptophan.

The histochemical fluorescence of those neurons in brainstem raphe nuclei which are presumed to contain serotonin is selectively and stereospecifically enhanced by L-tryptophan at doses that also produce an elevation in the concentration of serotonin. However, contrary to our assumptions, the increase in raphe fluorescence is not prevented by p-chlorophenylalanine, an inhibitor of serotonin synthesis. These results suggest that under some conditions derivatives of tryptophan other than, or in addition to, serotonin may be of significance in raphe neurons.

Animals↗