Sidney Udenfriend

Bio: Sidney Udenfriend is an academic researcher from Roche Institute of Molecular Biology. The author has contributed to research in topics: Tyrosine & Tyrosine hydroxylase. The author has an hindex of 102, co-authored 397 publications receiving 41669 citations. Previous affiliations of Sidney Udenfriend include National Institutes of Health & Washington University in St. Louis.

Fluorescamine: A Reagent for Assay of Amino Acids, Peptides, Proteins, and Primary Amines in the Picomole Range

Abstract: Fluorescamine is a new reagent for the detection of primary amines in the picomole range. Its reaction with amines is almost instantaneous at room temperature in aqueous media. The products are highly fluorescent, whereas the reagent and its degradation products are nonfluorescent. Applications are discussed.

Elucidation of the rate-limiting step in norepinephrine biosynthesis in the perfused guinea-pig heart

Abstract: Guinea-pig hearts were perfused with varying concentrations of the norepinephrine precursors, tyrosine, 3,4-dihydroxyphenylalanine (dopa) and 3,4-dihydroxyphenethylamine (dopamine). With all three precursors the rate of norepinephrine synthesis increased as the concentration in the perfusion fluid increased. However, only with tyrosine were maximal rates achieved (0.2 µg/g/hr) at concentrations below 5 x 10 -4 M. The apparent Km for the overall reaction (tyrosine → norepinephrine) was found to be comparable to that observed for conversion of tyrosine to dopa by purified tyrosine hydroxylase ( 2 x 10 -5 M). These and other factors indicate that conversion of tyrosine to dopa is the rate-limiting step in the formation of norepinephrine in the sympathetic nervous system. Although ascorbic acid has been shown to be a requirement for purified dopamine-β-oxidase activity severe seurvy did not diminish the ability of isolated heart to form norepinephrine from tyrosine or dopamine.

Regional studies of catecholamines in the rat brain. I. The disposition of [3H]norepinephrine, [3H]dopamine and [3H]dopa in various regions of the brain.

Abstract: NOREPINEPHRINE is found in appreciable amounts in mammalian brain tissue. VOGT (1954) showed that this amine was unequally distributed in various regions of the cat brain, the highest concentrations being found in the hypothalamus. Similar findings were reported for other animal species (BERTLER and ROSENGREN, 1959a; MCGEER, MCGEER and WADA, 1963) and man (SANO, GAMO, KAKIMOTO, TANAGUCHI, TAKE~ADA and NISHINUMA, 1959). Dopamine is also present in the brain in comparable amounts to norepinephrine (MONTAGU, 1957 ; CARLSSON, LINDQVIST, MAGNUSSON and WALDECK, 1958) but with a different regional distribution, the highest concentrations being in the corpus striatum of both animals and man (BERTLER and ROSENGREN, 1959a; SANO et al., 1959; EHRINGER and HORNYKIEWICZ, 1960; BERTLER, 1961). The anatomical distribution of these two catecholamines in the brain was confirmed by the use of fluorescent histochemical techniques which allow a precise description of the cellular localization of the amines in brain tissue (CARLSSON, FALK and HILLARP, 1962; DAHLSTROM and FUXE, 1964; FUXE, 1965). These techniques revealed that norepinephrine and dopamine are specifically localized in complex systems of neurons in the brain, a finding which lends support to the hypothesis that both amines may be neurotransmitters in the central nervous system. The metabolism of catecholamines in the rat brain was studied by introducing small amounts of radioactive norepinephrine or dopamine directly into the lateral ventricle (MILHAUD and GLOWINSKI, 1962, 1963; GLOWINSKI, KOPIN and AXELROD, 1965; GLOWINSKI, IVERSEN and AXELROD, 1966). By this approach the blood-brain barrier to catecholamines can be circumvented, penetration of the radioactive catecholamines into the brain being allowed. The disposition of PHInorepinephrine in the whole brain indicates that [3H]norepinephrine introduced into the lateral ventricle of the brain mixes with the endogenous amine and can be used as a tracer to study the biochemical behaviour of norepinephrine in the brain (GLOWINSKI and AXELROD, 1966). PHIDopamine, which is also taken up and retained in the brain, is rapidly metabolized and converted to norepinephrine (GLOWINSKI et a!., 1966). The unequal regional distribution of the endogeneous catecholamines in the brain led us to undertake a study of the disposition of radioactive norepinephrine and dopamine in various brain regions after intraventricular injection. The regional

Isolation and structure of a brain constituent that binds to the cannabinoid receptor

Abstract: Arachidonylethanolamide, an arachidonic acid derivative in porcine brain, was identified in a screen for endogenous ligands for the cannabinoid receptor. The structure of this compound, which has been named "anandamide," was determined by mass spectrometry and nuclear magnetic resonance spectroscopy and was confirmed by synthesis. Anandamide inhibited the specific binding of a radiolabeled cannabinoid probe to synaptosomal membranes in a manner typical of competitive ligands and produced a concentration-dependent inhibition of the electrically evoked twitch response to the mouse vas deferens, a characteristic effect of psychotropic cannabinoids. These properties suggest that anandamide may function as a natural ligand for the cannabinoid receptor.

Fibroblasts in cancer

Abstract: Tumours are known as wounds that do not heal - this implies that cells that are involved in angiogenesis and the response to injury, such as endothelial cells and fibroblasts, have a prominent role in the progression, growth and spread of cancers. Fibroblasts are associated with cancer cells at all stages of cancer progression, and their structural and functional contributions to this process are beginning to emerge. Their production of growth factors, chemokines and extracellular matrix facilitates the angiogenic recruitment of endothelial cells and pericytes. Fibroblasts are therefore a key determinant in the malignant progression of cancer and represent an important target for cancer therapies.