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Biomedical subjects

S Lieberman

Publications and source records attributed to S Lieberman.

At least 91 records · Page 5Linked to original sources
PubMed1977

Detection in bovine adrenal cortex of a lipoidal substance that yields pregnenolone upon treatment with alkali.

Bovine adrenal cortical tissue contains a lipoidal derivative of pregnenolone (3beta-hydroxy-pregn-5-en-20-one) from which the free steroid can be liberated by treatment with alkali. Evidence for the presence of such an entity comes from examination of a nonpolar extract of tissue from which pregnenolone and its sulfate had been removed by chromatography. Treatment of the nonpolar fraction with alkali followed by exhaustive chromatographic analysis led to the detection of pregnenolone. The steroid was identified by both gas chromatography/mass spectrometry and double isotope procedures. Quantitative analysis indicated that the three forms of pregnenolone are present in bovine adrenal cortical tissue in the following amounts (mug/kg): lipoidal derivative, 290; free steroid, 435; and sulfate, 65. Because the only known metabolic function of pregnenolone is to serve as a precursor of the steroid hormones, these findings have far-reaching implications for steroid hormone biochemistry.

Adrenal Cortex↗
PubMed1977

A survey of consultant psychiatrists' attitudes to their work, with particular reference to psychotherapy.

Ninety-six out of 137 consultant psychiatrists working for the majority of their time in the London area outside academic units returned questionnaires concerning attitudes to their work. Analysis of the 88 fully completed questionnaires suggested the existence of four relatively discrete but overlapping patterns of psychiatric practice in the Regions concerned, of which two largely excluded individual psychotherapy. These findings are discussed in relation to the education in psychotherapy of trainee psychiatrists working in mental hospitals.

Attitude of Health Personnel↗
PubMed1976

Identification of 17-methyl-18-norandrosta-5,13(17-dien-3beta-ol, the C19 fragment formed by adrenal side chain cleavage of a 20-aryl analog of (20S)-20-hydroxycholesterol.

Incubation of (20R)-20-phenyl-5-pregnene-3beta,20-diol, an aromatic analog of (23S)-20-hydroxycholesterol, with an adrenal mitochondrial preparation leads to the formation of four compounds: pregnenolone, phenol, a C8 ketone, acetophenone, and a nonpolar C19 compound. This latter compound has now been identified by reverse isotope dilution analysis and by gas chromatography/mass spectrometry as 17-methyl-18-norandrosta-5,13(17)-dien-3beta-ol. From these results it is evident that enzymatic fission of the C-17,20 bond of this synthetic derivative occurs. On the other hand, when (20S)-20-hydroxy[21-14C]cholesterol was used as substrate, the analogous cleavage did not take place. Thus, substitution of an aromatic group on C-20 facilitates side chain cleavage between that carbon atom and the nucleus whereas neither of the naturally occuring precursors, cholesterol or its 20-hydroxylated counterpart, are metabolized to a C8 fragment.

Adrenal Glands↗
PubMed1976

Biosynthesis of steroid sulfates by the boar testes.

The steroidogenic enzymes present in boar testicular tissue have been shown to use steroid sulfates as substrates. Pregnenolone sulfate, doubly labeled with 3H in the nucleus and 35S, was incubated with the microsomal fraction of boar testicular tissue and a reduced triphosphopyridine nucleotide generating system and 17-hydroxypregnenolone sulfate as well as dehydroisoandrosterone sulfate were isolated. These products had the same 3H to 35S ratio as the substrate demonstrating that the conversions had taken place with the sulfate group intact. Thus testicular 17-hydroxylase and C-17,20-desmolase can convert delta5-3beta-yl sulfates into products which still contain the sulfate group at C-3. An unusual steroid sulfate, doubly labeled 5,16-androstadien-3beta-yl sulfate, was also isolated demonstrating that such an olefin can be biosynthetized via steroid sulfate pathways. In a second experiment small amounts of [3H]-21-hydroxypregnenolone sulfate were isolated from the incubation of [3H]pregnenolone sulfate with microsomes from boar testes. The isolation of the 21-hydroxylated steroid sulfate is taken as support for the hypothesis that delta16 steroids are biosynthesized from their C21 precursors by events that are initiated by oxygenation at C-21.

Androgens↗
PubMed1976

Conversion of a C-20-deoxy-C21, steroid, 5-pregnen-3beta-ol, into testosterone by rat testicular microsomes.

5-[7ALPHA-3H] Pregnen-3beta-ol, a C-20-deoxy analog of pregnenolone, was synthesized and tested as a substrate for the enzyme system occurring in testes that cleaves the side chain of C21 steroids between C-17 and C-20. This C-20-deoxy C21 steroid was incubated with a microsomal preparation obtained from rat testis and was converted into testosterone in 5% yield. Another C-20-deoxy analog of pregnenolone, 5,20-pregnadien-3beta-ol, was not converted into testosterone by this enzyme system. The significance of this finding for the natural processes by which pregnenolone is converted by the same subcellular fraction into the male sex hormone is examined in the light of the hypothesis that intermediates involved in steroidogenesis are transient, reactive complexes of the appropriate reactants (steroids, oxygen, etc.) with specific enzymes.

Animals↗
PubMed1976

Fragments formed by the side chain cleavage of a 20-aryl analog of 20alpha-hydroxycholesterol by adrenal mitochondria.

An analog of 20alpha-hydroxycholesterol, (20R)-20-phenyl-5-pregnene-3beta,20-diol, which is completely substituted at C-22 was prepared with radioisotopes at various positions. The analog labeled with 3H at C-M and 14C at C-4 and C-IU was converted into radioactive pregnenolone by an enzyme preparation derived from adrenal mitochondria. Cleavage of the phenyl analog labeled with 3H in the aromatic ring by the same enzyme preparation led to the formation of [3H]phenol. Using the substrate doubly labeled with 14C at C-4 and 3H in the aromatic ring, it appeared that the products of the reactions, pregnenolone and phenol, were formed in equal amounts. During incubation of the side chain labeled substrate, another labeled fragment was formed. It was identified as acetophenone, a product resulting from cleavage of the C17,20 bond. The steroidal fragment corresponding to this C8 ketone was traced using nuclear label analog. From its nonpolar chromatographic properties it appears to be a C-17-deoxy-C19 steroid.

Adrenal Medulla↗
PubMed1975

The utilization of a consulting clinical psychologist within an urban vision training clinic.

Multi-disciplinary evaluation of children with learning problems is necessary in many cases. The private optometrist frequently has psychological resources available to him and his patients. In an urban setting with an inner city patient population, the clinical practitioner has much difficulty in referring and in retrieving psychological data. The function of a consulting psychologist as an attending staff member of the Visual Training Department of the Optometric Center of New York is described, and a preliminary report of 52cases referred for psychological consultation between September 1, 1972 and June 30, 1973 is presented.

Community Health Services↗