Search PubMed⌕ Search

Biomedical subjects

S Stein

Publications and source records attributed to S Stein.

At least 217 records · Page 12Linked to original sources
PubMed1977

Isolation and characterization of the opioid peptides from rat pituitary: beta-endorphin.

beta-Endorphin was isolated from 200 rat pituitaries by means of high-performance column chromatography, using sensitive fluorometric methods and a radioreceptor assay for opioid activity. The beta-endorphin was characterized as to molecular weight, amino acid composition, and mapping of tryptic peptides by a new microtechnique. It was found that rat beta-endorphin is identical to camel and sheep beta-endorphin. Furthermore, alpha-endorphin, Met-enkephalin, a nonpeptide morphine-like compound (MLC), and an additional unidentified opioid compound were detected in the extract of rat pituitary.

Amino Acids↗
PubMed1977

Isolation and characterization of the opioid peptides from rat pituitary: beta-lipotropin.

Rat beta-lipotropin was isolated from 40 anterior pituitaries using high efficiency chromatography columns and sensitive fluorometric methods. The beta-lipotropin was characterized as to molecular weight, amino acid composition, and generation of opioid activity by trypsinization. Other opioid peptides, as well as a precursor to opioid peptides with a molecular weight larger than that of beta-lipotropin, were observed in this tissue.

Amino Acids↗
PubMed1977

The impact of government insurance on a psychiatric clinic.

This paper considers the impact of a state medical insurance system on the structure of psychiatric services. The tendency of the upper socioeconomic classes to use private practitioners, and the lower classes to use public clinics, is examined before and after the imposition of the medical insurance system in Quebec in 1970. Data from one public clinic reveal a significant rise in the socioeconomic status of patients after Medicare. Alternative interpretations for the change in the clinic population are explored.

Hospitals, Psychiatric↗
PubMed1976

Fluorometric assay of vasopressin and oxytocin: a general approach to the assay of peptides in tissues.

A fluorometric method for the quantitative assay of vasopressin and oxytocin in individual rat pituitaries has been developed. Acid extracts of pituitaries are freed of amino acids and polyamines by passage over a copper-Sephadex column, and the peptides fraction is then labeled by reaction with fluorescamine. The resulting peptide fluorophors are separated by chromatography on a reverse-phase bonded column. Specificity of the procedure was ascertained by several criteria, including bioassay and amino-acid analysis of the eluted peptide fluorophors. The procedure serves as a model system for the assay of tissue peptides in the picomole range.

Amino Acids↗
PubMed1976

Resting state in normal and simian virus 40 transformed Chinese hamster lung cells.

Normal cell deprived of amino acids or serum factors enter a resting state, whereas cells transformed by wild-type simian virus 40 do not. The ability to enter a resting state is temperature-sensitive (ts) in cells transformed by a tsA mutant of simian virus 40. We shown further: (i) that when complete medium is added to resting cells, the length of time until the onset of DNA synthesis often exceeds the length of G1 in growing cells; (ii) that the length of this interval depends upon the conditions used to arrest cell growth; but (iii) that transferring cultures from medium depleted for one factor to medium depleted in a second factor never leads to a round of DNA synthesis; and (iv) that DNA synthesis does not resume rapidly when a resting culture of cells transformed by the tsA mutant is transferred to the permissive temperature in suboptimal medium. A model proposing that in suboptimal conditions cells leave the cell cycle and traverse a branch pathway to enter the resting state is consistent with these findings.

Cell Division↗