Search PubMed⌕ Search

Biomedical subjects

N A Solomon

Publications and source records attributed to N A Solomon.

32 records · Page 2Linked to original sources
PubMed1980

Cell-free cyclization of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine to isopenicillin N.

Cell-free cyclization of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine to isopenicillin N by lytic enzyme extracts of Cephalosporium acremonium M-0198 was stimulated by ferrous ions. The optimum concentration of FeSO4 was 80 microM. No additional stimulation was observed with ascorbate, adenosine 5'-triphosphate, or alpha-ketoglutarate, but Triton X-100 and sonication of the extracts increased activity. ZnSO4 was very inhibitory to enzyme activity; CuSO4 was somewhat less inhibitory, and the least effective of the three was MnCl2. The dimer of the tripeptide was converted to a penicillin that has the biological spectrum of isopenicillin N, and this reaction was also stimulated by FeSO4. We found that sonication can be used directly to prepare extracts with cyclization activity from mycelia, without preparing protoplast lysates. The kinetics of cyclase appearance and disappearance during fermentation were similar to those of ring-expansion activity, i.e., enzyme appeared and peaked 13 h after growth ceased and then disappeared.

Acremonium↗
PubMed1979

The effects of injection site, age, and body position on cervical venous reflux.

The effects of injection site, age, and body position on cervical venous reflux during carotid radionuclide angiography were studied. Adults injected via the left arm while supine were more likely to show reflux; neither the position nor the side injected was important in children. Right arm injection is preferred for adults; adults injected via the left arm should be erect if possible.

Age Factors↗
PubMed1976

Persisting perfusion defects after bronchoscopic removal or spontaneous expulsion of aspirated foreign objects.

Follow-up lung scans were obtained in 9 children to determine whether perfusion lung scanning could be used to verify completeness of foreign-body removal. In 4 patients, extensive perfusion defects were present 4-19 days after removal of the object. In 1 patient, the area of hypoperfusion was larger than the territory served by a persistently obstructed lobar bronchus. Follow-up lung scans are of limited value for verifying completeness of foreign-body removal and localization of retained fragments.

Airway Obstruction↗
PubMed1975

Identification of tachistoscopically exposed symmetrical and asymmetrical letter arrays.

Six-letter arrays containing symmetrical, e.g., H, M, T, or asymmetrical letters, e.g., J, K, R, were tachistoscopically exposed bilaterally for 100 msec. to 100 college students. Significantly more asymmetrical than symmetrical letters were identified, and significantly more Ss identified more asymmetrical than symmetrical items. This experiment, which incorporated methodological considerations suggested by Harcum (1964) and Bryden (1968), corroborates their findings. Their ideas and other findings were used to account for the data. Asymmetrical letters have more intrinsic left-to-right directionality than symmetrical elements. The rapidly fading after-stimulation of tachistoscopically presented alphabetical material is usually scanned from left to right. Individual array letters might also be scanned in the same direction. Confluence of directionality of letter and scan, which obtains only with asymmetrical letters, might have typically allowed asymmetrical targets to be scanned more rapidly and, consequently, more efficiently than symmetrical displays.

Afterimage↗