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Wilk S, Orlowski M. Evidence that pituitary cation-sensitive neutral endopeptidase is a multicatalytic protease complex. J Neurochem 1983; 40:842-9. [PMID: 6338156 DOI: 10.1111/j.1471-4159.1983.tb08056.x] [Citation(s) in RCA: 306] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Pituitary cation-sensitive neutral endopeptidase splits peptide bonds on the carboxyl side of hydrophobic amino acids (chymotrypsin-like activity), basic amino acids (trypsin-like activity), and acidic amino acids (peptidyl-glutamyl-peptide bond hydrolyzing activity). All three activities copurify, are inhibited by cations, and reside in a single high-molecular weight soluble protein complex. Treatment with sodium dodecylsulfate and 2-mercaptoethanol dissociates this complex into five low-molecular weight components. Incubation of the complex at 37 degrees C in buffers of high ionic strength produces aggregation and progressive loss of all three activities. Experiments with inhibitors and activators indicate that the three activities are catalyzed by distinct components. Benzyloxycarbonyl-glycyl-glycyl-leucinal, a peptide aldehyde transition state analog of the substrate used to measure the chymotrypsin-like activity, exclusively inhibits that activity (Ki = 2.5 x 10(-4) M), while markedly activating the trypsin-like activity. The trypsin-like activity is inhibited by leupeptin (Ki = 1.2 x 10(-6) M) and by sulfhydryl blocking agents, and activated by thiols, suggesting that this activity is due to a thiol protease. The peptidylglutamyl-peptide hydrolyzing activity is activated almost 10-fold by low concentrations of sodium dodecylsulfate, inhibited by bovine serum albumin, and suppressed at high enzyme concentrations, suggesting that this component readily interacts with other proteins, including the complex itself. The results indicate that cation-sensitive neutral endopeptidase is a multicatalytic protease complex whose distinct proteolytic activities are associated with separate components of this high-molecular weight protein.
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102
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Wilk S, Orlowski M. Determination of specificity of endopeptidases by combined high-performance liquid chromatography and amino acid analysis. J Chromatogr A 1982; 249:121-9. [PMID: 6757262 DOI: 10.1016/s0021-9673(00)80238-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The specificity of three neutral endopeptidases toward several biologically active peptides was determined by combined high-performance liquid chromatography and amino acid analysis of the degradation products. Incubation mixtures were chromatographed on a reversed-phase column equilibrated with a mixture of acetonitrile and potassium phosphate buffer (0.05 M; pH 2.0). Reaction products were eluted with a linear gradient of acetonitrile and the absorbance of the effluent monitored at 210 nm. Fractions corresponding to discrete peaks were subjected to quantitative amino acid analysis. The peptide bond undergoing cleavage is readily assigned from the knowledge of the primary structure of the peptide and the amino acid composition of the reaction products.
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103
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Wilk S, Amtsberg G, Meier C. [Serotyping and drug resistance of Escherichia coli strains in healthy dogs and dogs with enteritis]. BERLINER UND MUNCHENER TIERARZTLICHE WOCHENSCHRIFT 1982; 95:271-5. [PMID: 6753828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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104
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Dresdner K, Barker LA, Orlowski M, Wilk S. Subcellular distribution of prolyl endopeptidase and cation-sensitive neutral endopeptidase in rabbit brain. J Neurochem 1982; 38:1151-4. [PMID: 7038048 DOI: 10.1111/j.1471-4159.1982.tb05362.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The subcellular distribution of prolyl endopeptidase, and of cation-sensitive neutral endopeptidase, two enzymes actively metabolizing many neuropeptides, was determined in homogenates of rabbit brain. The subcellular distribution of both enzymes was more similar to lactate dehydrogenase, a cytoplasmic enzyme marker, than to choline acetyltransferase, a synaptosomal marker. Only 35% of the activity of these two neutral endopeptidases was found in the crude mitochondrial fraction (P2), the bulk of the remaining activity being associated with the high-speed supernatant. Prolyl endopeptidase and cation-sensitive neutral endopeptidase thus can be regarded as mainly cytoplasmic enzymes in the rabbit brain.
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105
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Almenoff J, Wilk S, Orlowski M. Membrane bound pituitary metalloendopeptidase: apparent identity to enkephalinase. Biochem Biophys Res Commun 1981; 102:206-14. [PMID: 7030340 DOI: 10.1016/0006-291x(81)91508-4] [Citation(s) in RCA: 153] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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106
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Orlowski M, Wilk S. Purification and specificity of a membrane-bound metalloendopeptidase from bovine pituitaries. Biochemistry 1981; 20:4942-50. [PMID: 7028098 DOI: 10.1021/bi00520a021] [Citation(s) in RCA: 143] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A metalloendopeptidase optimally active at a neutral pH was purified 10000-fold from particulate fractions of bovine pituitaries. The solubilized enzyme has an apparent molecular weight of about 90 000, as determined by gel filtration on Sephadex G-200 and G-100 columns. The enzyme is not sensitive to inhibition by SH-blocking agents, diisopropyl fluorophosphate, leupeptin, pepstatin, antipain, and chymostatin. Thiols and metal chelators such as ethylenediaminetetraacetic acid (EDTA) o-phenanthroline are inhibitory. An EDTA-treated enzyme can be reactivated by several divalent metal ions, with zinc giving reactivation at the lowest concentrations. The specificity and kinetic parameters of the enzyme were studied with a series of synthetic peptide naphthylamides. The enzyme cleaves bonds in which the amino group is provided by a hydrophobic amino acid residue (position P1'). Replacement of this residue by small neutral amino acids decreases or virtually eliminates activity. The nature of substituents in positions P1, P2, P3, and P4 greatly influences specificity. Relatively high kcat and kcat/Km ratios were obtained with substrates containing arginine residues in positions P1 and P2. In such cases the impression of a "trypsin-like" activity was created. High reaction rates were also observed with substrates containing small neutral amino acids in positions P1 and P2, provided that position P3 was occupied by the acidic (polar) glutaryl residue. Replacement of this residue with hydrophobic substituents greatly decreased the rate of reaction. When positions P1 and P2, however, were occupied by arginine residues, the unfavorable effect of hydrophobic substituents in position P3 or P4 on catalysis was eliminated.
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107
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Orlowski M, Wilk S. A multicatalytic protease complex from pituitary that forms enkephalin and enkephalin containing peptides. Biochem Biophys Res Commun 1981; 101:814-22. [PMID: 7030330 DOI: 10.1016/0006-291x(81)91823-4] [Citation(s) in RCA: 98] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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108
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Lin CW, Maayani S, Wilk S. [3H]dihydroergocryptine binding to bovine striatal membranes defined by a low d-butaclamol concentration: antagonism by substituted benzamides. Biochem Pharmacol 1981; 30:1305-14. [PMID: 6168265 DOI: 10.1016/0006-2952(81)90314-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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109
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Wilk S, Orlowski M. Cation-sensitive neutral endopeptidase: isolation and specificity of the bovine pituitary enzyme. J Neurochem 1980; 35:1172-82. [PMID: 6778972 DOI: 10.1111/j.1471-4159.1980.tb07873.x] [Citation(s) in RCA: 261] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A highly purified preparation of a cation-sensitive neutral endopeptidase was obtained from bovine pituitaries. The enzyme constitutes almost 0.1% of the protein in bovine pituitary homogenates. Polyacrylamide gel electrophoresis of the enzyme showed a single protein band, and in gel filtration experiments on calibrated Sepharose 6B columns the enzyme eluted slightly ahead of thyroglobulin, suggesting an apparent molecular weight of about 700,000. Polyacrylamide gel electrophoresis in SDS-containing buffers indicated the presence of three major components with molecular weights ranging from about 24,000 to 28,000. The enzyme hydrolyzes bonds between hydrophobic and small neutral amino acids in both model synthetic substrates and biologically active peptides such as substance P, LH-RH, and bradykinin. Peptide bonds in which the carbonyl group is contributed by a glutamyl or arginyl residue are also hydrolyzed, especially if they are preceded in the sequence by hydrophobic amino acids. Leupeptin exclusively inhibited enzymatic activity toward the arginine-containing substrates. This observation, together with the high molecular weight and broad specificity of the enzyme, raised the possibility that the isolated enzyme represents a proteolytic complex composed of units with distinctly different activities. Preliminary attempts to dissociate the enzyme into catalytic units of lower molecular weight were not successful and led to loss of activity.
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110
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Stanley M, Wilk S. The differential effects of morphine, oxotremorine and antipsychotic drugs on DOPAC concentrations in rat brain. J Pharm Pharmacol 1980; 32:567-70. [PMID: 6106695 DOI: 10.1111/j.2042-7158.1980.tb12998.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The effects of morphine and oxotremorine on concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) in the rat striatum and tuberculum olfactorium (TO) have been compared with the effects of the antipsychotic drugs haloperidol, chlorpromazine and clozapine. All the drugs elevated DOPAC concentrations in both brain regions. While the dose-response curves for the antipsychotic drugs were parallel, had steep slopes and similar maxima, the curves for morphine and oxotremorine were irregularly shaped but the curve for morphine in the TO had some similarity to that of the antipsychotic drugs. From these findings, it is concluded that the dose-dependent increase in striatal DOPAC effected by antipsychotic drugs can be used to differentiate them from other drugs known to elevate dopamine metabolites.
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111
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Orlowski M, Michaud C, Wilk S. Generation of methionine and leucine-enkephalin from precursor molecules by cation-sensitive neutral endopeptidase of bovine pituitary. Biochem Biophys Res Commun 1980; 94:1145-53. [PMID: 6994737 DOI: 10.1016/0006-291x(80)90539-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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112
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Lin CW, Maayani S, Wilk S. The effect of typical and atypical neuroleptics on binding of [3H]spiroperidol in calf caudate. J Pharmacol Exp Ther 1980; 212:462-8. [PMID: 6102144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The effect of typical and atypical neuroleptics on the binding of [3H]spiroperidol to calf caudate membranes was studied. Saturable or specific binding was defined as the difference between binding in the absence and in the presence of 1 microM d-butaclamol. Scatchard analysis revealed nonhomogeneity of the saturable sites. Inhibition constants (Ki) and IC50 values for various typical and atypical neuroleptics and for two clinically inactive butyrophenones were determined. The Ki and IC50 values of typical neuroleptics paralleled their potencies in vivo. By contrast, the binding potencies of atypical neuroleptics did not correlate with their effects in vivo. For example, the clinically active drug clozapine has an IC50 value similar to the clinically inactive butyrophenone AHR-1900. U-25, 927, another clinically inactive butyrophenone that does not increase dopamine turnover is more potent in the binding assay than perlapine, a drug that increases dopamine turnover and elevates serum prolactin levels. The most striking discrepancy between binding and properties in vivo was found for the benzamide derivatives, sulpiride and metoclopramide. These clinically active agents, which increase dopamine turnover, have much higher Ki values than the clinically inactive butyrophenones. It is concluded that binding assays with [3H]spiroperidol in calf caudate cannot account for the antidopamine effects in vivo of atypical neuroleptics.
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113
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Orlowski M, Mizoguchi H, Wilk S. N-acyl-gamma-glutamyl derivatives of sulfamethoxazole as models of kidney-selective prodrugs. J Pharmacol Exp Ther 1980; 212:167-72. [PMID: 6101340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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114
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Wilk S, Benuck M, Orlowski M, Marks N. Degradation of luteinizing hormone-releasing hormone (LHRH) by brain prolyl endopeptidase with release of des-glycinamide LHRH and glycinamide. Neurosci Lett 1979; 14:275-9. [PMID: 394029 DOI: 10.1016/0304-3940(79)96161-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A highly purified preparation of rabbit brain prolyl endopeptidase cleaved the decapeptide luteinizing hormone-releasing hormone (LHRH) at the ProGly . NH2 bond leading to the release within 1-3 h incubation at 37 degrees C of des-glycinamide LHRH and glycinamide. Evidence for this site of cleavage was obtained by the detection of glycinamide or glycine and groups by a microdanyslation procedure, and by separation of the breakdown products by high performance liquid chromatography (HPLC) on a revers phase C-18 column. Incubation led to the appearance of two new peaks as detected by HPLC one of which was collected and shown to have the composition consistent with des-glycinamide LHRH. The other peak ran in the position identical to that of authentic glycinamide. Results suggest that prolyl endopeptidase could play a role in the inactivation of LHRH in vivo.
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115
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Wilk S, Orlowski M. Degradation of bradykinin by isolated neutral endopeptidases of brain and pituitary. Biochem Biophys Res Commun 1979; 90:1-6. [PMID: 496963 DOI: 10.1016/0006-291x(79)91581-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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116
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Mizoguchi H, Orlowski M, Wilk S, Green JP. gamma-Glutamyl DOPA and gamma-glutamyl dopamine: effect on plasma glucose levels. Eur J Pharmacol 1979; 57:239-45. [PMID: 488163 DOI: 10.1016/0014-2999(79)90371-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
gamma-Glutamyl-L-3,4-dihydroxyphenylalanine (gamma-glutamyl DOPA) and gamma-glutamyldopamine (gamma-glutamyl DA) are kidney specific prodrugs. Their effect on plasma glucose levels in the rat was compared to that of L-DOPA and dopamine (DA) after a 30 min intravenous infusion. L-DOPA and DA induced hyperglycemia after 15 min of druginfusion. A more marked and protracted elevation of plasma glucose was observed after infusion of gamma-glutamyl DA. By gamma-glutamyl DOPA had no effect on plasma glucose levels in spite of the high accumulation of DA in the pancreas after this prodrug. Of the various dopamine produrgs studied only gamma-glutamyl DOPA was not hyperglycemic in doses that are known to increase renal plasma flow in the rat. A simplified new procedure for the synthesis of gamma-glutamyl DA is described.
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117
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Orlowski M, Wilk E, Pearce S, Wilk S. Purification and properties of a prolyl endopeptidase from rabbit brain. J Neurochem 1979; 33:461-9. [PMID: 469536 DOI: 10.1111/j.1471-4159.1979.tb05176.x] [Citation(s) in RCA: 151] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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118
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119
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Wilk S, Pearce S, Orlowski M. Identification and partial purification of a cation-sensitive neutral endopeptidase from bovine pituitaries. Life Sci 1979; 24:457-64. [PMID: 431331 DOI: 10.1016/0024-3205(79)90218-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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120
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Wilk S, Stanley M. Clozapine concentrations in brain regions: relationship to dopamine metabolite increase. Eur J Pharmacol 1978; 51:101-7. [PMID: 699976 DOI: 10.1016/0014-2999(78)90334-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Levels of clozapine in rat striatum and tuberculum olfactorium were quantitated by a gas chromatographic technique. The relationship of the increase in 3,4-dihydroxyphenylacetic acid (DOPAC) in these regions produced by clozapine to the concentration of clozapine was explored. One hour after 10, 20 or 40 mg/kg clozapine i.p. the concentration of drug increased in proportion to the dose and at each dose was similar in striatum and T.O. The percent increase in DOPAC in both areas was related to the clozapine concentration in a typical dose--response manner and was greater in the striatum than the T.O. A relatively high concentration of clozapine (40 micron) was required to produce a half-maximal elevation of DOPAC. Striatal clozapine levels were similar in acutely and chronically treated animals. The concentrations of clozapine in striatum and T.O. reflect the dose injected and do not account for its atypical properties.
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121
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Rotrosen J, Angrist BM, Gershon S, Aronson M, Gruen P, Sachar EJ, Denning RK, Matthysse S, Stanley M, Wilk S. Thiethylperazine; clinical antipsychotic efficacy and correlation with potency in predictive systems. ARCHIVES OF GENERAL PSYCHIATRY 1978; 35:1112-8. [PMID: 99115 DOI: 10.1001/archpsyc.1978.01770330086008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A one-to-one relationship between clinical antipsychotic potency and pharmacologic dopaminergic antagonism is implicit in the dopamine hypothesis of neuroleptic action. Thiethylperazine maleate, a classical antiemetic phenothiazine, displays dopaminergic antagonism in behavioral, neurochemical, and neuroendocrine systems, but is paradoxical insofar as it is thought not to possess clinical neuroleptic activity. In three tests of dopaminergic antagonism--elevation of levels of CSF homovanillic acid in monkeys, striatal dihydroxyphenylacetic acid in rats, and prolactin in man--as well as in a clinical trial of neuroleptic efficacy in schizophrenics, thiethylperazine was fully active and approximately three times as potent as chlorpromazine. Differences in efficacy between this and earlier clinical studies can be accounted for on the basis of dosage.
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122
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Wilk S, Mizoguchi H, Orlowski M. gamma-Glutamyl dopa: a kidney-specific dopamine precursor. J Pharmacol Exp Ther 1978; 206:227-32. [PMID: 660553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
gamma-Glutamyl derivatives of amino acids and peptides are selectively accumulated in the kidney and introduced into the metabolism of kidney cells. gamma-Glutamyl L-3,4-dihydroxyphenylalanine (gamma-glutamyl dopa) was synthesized both chemically and enzymatically. Injection of this derivative into mice led to a selective generation of dopamine in the kidney as a consequence of the sequential action of gamma-glutamyl transpeptidase and aromatic L-amino acid decarboxylase, two enzymes which are highly concentrated in the kidney. The concentration of dopamine in the kidney after gamma-glutamyl dopa was almost 5 times higher than that after an equivalent dose of L-dopa. Infusion of 10 nmol/g/30 min of gamma-glutamyl dopa to rats produced a 60% increase in renal plasma flow. By contrast the same dose of L-dopa had no effect on renal plasma flow. Only a small pressor effect was observed after the infusion dose of gamma-glutamyl dopa was increased 20-fold indicating that the systemic effects of this pro-drug slight. The results suggest that the pro-drug gamma-glutamyl dopa can be used as a specific renal vasodilator.
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Abstract
The relationship of human brain levels of 3,4-dihydroxyphenylacetic acid (DOPAC) to cerebrospinal fluid levels of this domapine (DA) metabolite was studied. The effect of postmortem delay was evaluated in the rat. DOPAC was resistant to postmortem changes in brain kept in situ. The level of DOPAC (free and conjugated) determined in DA-rich areas of six human brains amounted to only a fraction of the homovanillic acid (HVA) found in the same regions. The DOPAC/HVA ratio in human brain was similar to that found in CSF. We conclude that HVA is the major DA metabolite in human brain and that DA metabolite levels in CSF reflect DA metabolite levels in brain.
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Abstract
The synthesis of ophthalmic acid, an analogue of glutathione, was studied in vivo in mouse liver and kidney after administration of either L-alpha-aminobutyrate or L-gamma-glutamyl-L-alpha-aminobutyrate as precursor. L-alpha-aminobutyrate accumulated to a much greater extent, and induced a much greater synthesis of ophthalmic acid in the liver than in the kidney. In contrast, L-gamma-glutamyl-L-alpha-aminobutyrate initiated a large and more rapid synthesis of ophthalmic acid in the kidney than in the liver. Experiments with L-gamma-[G(-14)C]glutamyl-L-alpha-aminobutyrate showed that, although part of the dipeptide is degraded to its constituent amino acids, a significant proportion is directly incorporated into kidney ophthalmic acid. In contrast L-gamma-glutamyl-L-alpha-aminobutyrate serves poorly as a direct precursor of liver ophthalmic acid. The present results show that kidney gamma-glutamyl tripeptide synthesis can proceed directly from an exogenous gamma-glutamyl dipeptide precursor.
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125
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Orlowski M, Wilk S. Kidney as a site of uptake and metabolism of gamma-glutamyl compounds. CURRENT PROBLEMS IN CLINICAL BIOCHEMISTRY 1977; 8:66-72. [PMID: 616382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
gamma-Glutamyl derivatives of amino acids are extensively metabolized and accumulated in the kidney. The kideny also has a high capacity to synthesize ophthalmic acid, an analog of glutathione. These processes can be attributed to the high activity in the kidney of enzymes that both degrade and synthesize glutathione. Th possibility of using the gamma-glutamyl group as a carrier for the introduction of compounds containing an amino function into kidney metabolism was explored. Administration of L-gamma-glutamyl-L-3,4-di-hydroxyphenylalanine (gamma-glutamyl-DOPA) to rats led to the accumulation of gamma-glutamyl-DOPA in the kidney, release of DOPA and its conversion to dopamine by the action of aromatic amino acid decarboxylase. Dopamine actively generated in the kidney increased renal plasma flow and sodium excretion. No systemic effects or untoward reactions attributable to this amine were observed. It is suggested that gamma-glutamyl derivatives of certain drugs may be useful as kidney specific prodrugs.
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126
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Stanley M, Wilk S. The effect of antipsychotic drugs and their clinically inactive analogs on dopamine metabolism. Eur J Pharmacol 1977; 44:293-302. [PMID: 19267 DOI: 10.1016/0014-2999(77)90302-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Changes in dopamine metabolite levels in the rat striatum and tuberculum olfactorium, following the administration of three non-antipsychotic butyrophenones (AL-499, AHR-1900 and U-25,927) and a non-antipsychotic benzazepine (SCH-12,679), were compared to the effects seen following the antipsychotics haloperidol, chlorpromazine and clozapine. The non-antipsychotics, although clinically ineffective, were reported as active in a variety of animal screening tests. Haloperidol, chlorpromazine and clozapine produced a dose-dependent increase in 3,4-dihydroxyphenylacetic acid (DOPAC) levels in both regions. Of the non-antipsychotic drugs only AHR-1900 significantly elevated the level of DOPAC, however, the slope of its dose-response curve was atypically flat in comparison to the dose-response curves of drugs with known antipsychotic efficacy. Moreover, the maximal effect of AHR-1900 observed at a dose of 40 mg/kg was less than the ED50 effect of haloperidol which occurs at a 250 fold lower dose. It is concluded that the dose-dependent elevation of DOPAC in the striatum and tuberculum olfactorium of the rat is a good predictor of antipsychotic efficacy.
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128
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Abstract
A model for the prediction of antipsychotic efficacy based on the dose-dependent increase in levels of 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum and tuberculum olfactorium of the rat is presented. The effect of perlapine, a sleep-promoting and sedative agent reported to lack antipsychotic efficacy, was compared in this system to haloperidol, chlorpromazine and clozapine. All four drugs produced a dose-dependent increase in DOPAC in the two dopamine-rich structures. The potency of perlapine was similar to that of chlorpromazine. Dopamine, assayed in the striatum and tuberculum olfactorium by a new gas chromatographic procedure was not altered by perlapine. The time--action curves for perlapine and clozapine were virtually identical both in the striatum and in the tuberculum olfactorium. All four drugs also elevated homovanillic acid to a similar extent. These results indicate that perlapine should be re-evaluated clinically. We predict that such trials will reveal that perlapine does possess antipsychotic efficacy.
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129
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Orlowski M, Wilk S. Metabolism of gamma-glutamyl amino acids and peptides in mouse liver and kidney in vivo. EUROPEAN JOURNAL OF BIOCHEMISTRY 1976; 71:549-55. [PMID: 12970 DOI: 10.1111/j.1432-1033.1976.tb11144.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The metabolism in vivo of gamma-glutamyl amino acids and peptides was studied in the mouse after administration of loading doses of L-gamma-glutamyl-2-aminobutyrate and several other gamma-glutamyl compounds, including glutathione. A great and rapid accumulation of glutamate, glutamine, aspartate and pyrrolidone carboxylate was observed in the kidney. Similarly, after administration of a tracer dose of L-gamma-[14C]glutamyl-L-2-aminobutyrate a rapid incorporation of label into kidney glutamate, glutamine and aspartate was found. These results suggest that both the hydrolytic and gamma-glutamyl transfer reactions catalyzed by gamma-glutamyl transpeptidase are active in the renal handling of gamma-glutamyl compounds. Indirect evidence was obtained that L-gamma-glutamyl-2-aminobutyrate is partially taken up by the kidney cell in an intact form. In contrast to the kidney, administration of several gamma-glutamyl derivatives did not cause an increase in liver glutamate, glutamine and pyrrolidone carboxylate. After administration of L-gamma-glutamyl-2-aminobutyrate only a slight increase in liver aspartate and pyrrolidone carboxylate was observed. Experiments with L-gamma-[14C]glutamyl-L-2-aminobutyrate suggest that this derivative is largely first degraded to its component amino acids (probably in the kidney) before entering into the metabolism of the liver cell. gamma-Glutamyl transpeptidase may function in the metabolism and transport of glutathione and other gamma-glutamyl compounds in a manner analogous to the function of dipeptidases and disaccharidases in the metabolism and transport of dipeptides and disaccharides respectively.
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130
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Abstract
Dopamine metabolism in the nucleus accumbens of the rat was studied by gas chromatographic quantitation of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). The ratio of DOPAC/HVA in the nucleus accumbens was significantly greater than the same ratio in the striatum. Dose-response curves for the increase in DOPAC and HVA in the nucleus accumbens and striatum 2 h after clozapine were generated. The effect of clozapine on dopamine metabolism was similar in both structures.
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131
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Abstract
This report deals with a series of experimental approaches carried out in clinical studies to attempt to examine the role of amines in relationship to affective state and the mode of action of thymoleptic agents. Attempts have been made to examine enzymes, amines and other metabolites in biological fluids to assess the role of catecholamines and indoleamines in these disorders. Synthesis inhibitors were employed in studies where antidepressant drug-induced remission was initiated and the effect of two inhibitors was assessed on the clinical state. The results are presented and discussed in regard to the significance of the role of serotonin in depressive states and the action of thymoleptic agents.
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132
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Wilk S, Watson E, Stanley ME. Differential sensitivity of two dopaminergic structures in rat brain to haloperidol and to clozapine. J Pharmacol Exp Ther 1975; 195:265-70. [PMID: 1185596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The mechanisms underlying the dissociation of the extrapyramidal and antipsychotic properties of haloperidol as compared to clozapine were explored by studying the effects of these drugs on dopamine metabolism in the straitum and tuberculum olfactorium (TO) of the rat. Homovanillic acid and 3,4-dihydroxyphenylacetic acid were simutaneously measured in these regions by a gas chromatographic techinque after treating the rats with different doses of the drugs. Dose-response curves and time-action curves were generated. For both drugs, a higher dose was required to achieve half-maximal metabolite elevation in the TO as compared to the striatum. The apparent differential sensitivity to haloperidol was attributed to differences in time to peak response. The time to peak response to clozapine was similar in both structures. Thus, the striatum appears to be more sensitive to clozapine than the TO with respect to elevation of dopamine metabolites. The effect of haloperidol on dopamine metabolism in the striatum was more persistent than that in the TO. After 4 hours, metabolite levels were still elevated in the striatum, whereas after 2 hours they returned to base line in the TO. The extrapyramidal effects of haloperidol may be due to the persistent action of this drug on dopamine metabolism in the striatum, and the lack of extrapyramidal effects of clozapine may be due to its brief action on dopamine metabolism in the striatum.
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Orlowski M, Wilk S. In vivo inhibition of gamma-glutamylcysteine synthetase by L-methionine-RS-sulfoximine; influence on intermediates of the gamma-glutamyl cycle. J Neurochem 1975; 25:601-6. [PMID: 1194915 DOI: 10.1111/j.1471-4159.1975.tb04374.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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134
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Wilk S, Orlowski M. Determination of pyrrolidone carboxylate and gamma-glutamyl amino acids by gas chromatography. Anal Biochem 1975; 69:100-13. [PMID: 1211619 DOI: 10.1016/0003-2697(75)90571-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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135
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Wilk S. Neuroleptic drugs and dopamine metabolism. PSYCHOPHARMACOLOGY BULLETIN 1975; 11:73. [PMID: 1153686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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136
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Orlowski M, Wilk S. Intermediates of the gamma-glutamyl cycle in mouse tissues. Influence of administration of amino acids on pyrrolidone carboxylate and gamma-glutamyl amino acids. EUROPEAN JOURNAL OF BIOCHEMISTRY 1975; 53:581-90. [PMID: 237763 DOI: 10.1111/j.1432-1033.1975.tb04101.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
GAMMA-Glutamyl transpeptidase, gamma-glutamyl cyclotransferase, L-pyrrolidone carboxylate hydrolase, gamma-glutamylcysteine synthetase and glutathione synthetase, the enzymes of the gamma-glutamyl cycle, were found in mouse brain, liver and kidney. The activity of L-pyrrolidone carboxylate hydrolase was many times lower than the activities of the other enzymes, and thus the conversion of L-pyrrolidone carboxylate to L-glutamate is likely to be the rate-limiting step of the cycle. The specificity of gamma-glutamyl cyclotransferase from mouse tissues was similar to that from rat tissues. The concentration of pyrrolidone carboxylate and gamma-glutamyl amino acids, intermediates of the gamma-glutamyl cycle, was determined by a gas chromatographic procedure coupled with electron capture detection. Administration of L-2-aminobutyrate, an amino acid that is utilized as substrate in the reaction catalyzed by gamma-glutamylcysteine synthetase, led to a large accumulation of gamma-glutamyl-2-aminobutyrate and pyrrolidone carboxylate in mouse tissues. L-Methionine-RS-sulfoximine, an inhibitor of gamma-glutamylcysteine synthetase, abolished the increase in concentration of pyrrolidone carboxylate. No accumulation of pyrrolidone carboxylate was observed after L-cysteine. The separate administration of several protein amino acids had little effect on the concentration of pyrrolidone carboxylate; however formation of small amounts of the corresponding gamma-glutamyl derivatives (e.g. gamma-glutamylmethionine and gamma-glutamylphenylalanine) was detected. These intermediates are probably formed by transpeptidation between glutathione and the corresponding amino acid, catalyzed by gamma-glutamyl transpeptidase. The concentration of pyrrolidone carboxylate increased significantly after administration of a mixture containing all protein amino acids, the highest increase occurring in the kidney. The results suggest that two separate pathways for the formation of gamma-glutamyl amino acids and pyrrolidone carboxylate exist in vivo. One of these results from the function of gamma-glutamylcysteine synthetase in glutathione synthesis. The other pathway involves the amino-acid-dependent degradation of glutathione, mediatedby gamma-glutamyl transpeptidase. Only very small amounts of free intermediates are apparently derived from the latter pathway, suggesting that the gamma-glutamyl amino acids formed in this pathway are either enzyme-bound or are directly hydrolyzed to glutamate and free amino acid.
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Watson E, Wilk S. Assessment of cerebrospinal fluid levels of dopamine metabolites by gas chromatography. Psychopharmacology (Berl) 1975; 42:57-6. [PMID: 1153623 DOI: 10.1007/bf00428826] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The acid metabolites of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were determined in lumbar cerebrospinal fluid (CSF) by a new procedure. After gas chromatographic separation, the pentafluoroprionyl 2,2,3,3,3-pentafluoro-1-propionyl esters of DOPAC and HVA were analyzed by electron capture detection. Normal HVA levels were quantitated in as little as 0.1 ml CSF. No significant amounts of DOPAC (less than 1 ng/ml) were found in any of the drug-free samples analyzed. Levels of DOPAC increased only marginally in the CSF of patients receiving acute or chronic doses of L-Dopa. Baseline HVA levels ranged from 4.5--50 ng/ml with a mean value of 23 ng/ml. These studies demonstrate that HVA is the major dopamine metabolite in human CSF.
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Wilk S, Watson E, Travis B. Evaluation of dopamine metabolism in rat striatum by a gas chromatographic technique. Eur J Pharmacol 1975; 30:238-43. [PMID: 1126361 DOI: 10.1016/0014-2999(75)90105-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Dopamine metabolism in rat striatum was evaluated by gas chromatographic quantitation of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). The level of DOPAC (5.21 nmoles/g plus or minus 0.40 S.E.M., n equals 12) exceeded that HVA (3.63 nmoles/g plus or minus 0.25 S.E.M., n equals 12). 2 hr following administration of probenecid (200 mg/kg i.p.) the level of striatal HVA was approximately doubled whereas the level of DOPAC was not significantly elevated. Pargyline (75 mg/kg i.p.) poduced a rapid depletion of DOPAC and HVA. the rate of disappearance of DOPAC (t1/2 equals 10 min) exceeded that of HVA (t1/2 equals 18 min). Rates of metabolite formation were computed assuming steady state kinetics. The rate formation of DOPA (20.5 nmoles/g/hr) was much greater than that of HVA (10.1 nmoles/g/hr). We conclude that DOPAC is the major dopamine metabolite in rat striatum and that its measurement may provide the best index of functional neuronal activity in this species.
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Abstract
The occurrence of the major dopamine metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the tuberculum olfactorium of the rat was demonstrated by gas chromatography. The ratio of DOPAC to HVA in the tuberculum olfactorium was greater than the ratio of these metabolites in the striatum. The effect of pargyline and probenecid on dopamine metabolite levels was similar for both the tuberculum olfactorium and striatum.
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Watson E, Travis B, Wilk S. Simultaneous determination of 3,4-dihydroxyphenylacetic acid and homovanillic acid in milligram amounts of rat striatal tissue by gas-liquid chromatography. Life Sci 1974; 15:2167-78. [PMID: 4621013 DOI: 10.1016/0024-3205(74)90033-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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141
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Watson E, Wilk S. Derivatization and gas chromatographic determination of some biologically important acids in cerebrospinal fluid. Anal Biochem 1974; 59:441-51. [PMID: 4838778 DOI: 10.1016/0003-2697(74)90297-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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142
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Shopsin B, Wilk S, Sathananthan G, Gershon S, Davis K. Catecholamines and affective disorders revised: a critical assessment. J Nerv Ment Dis 1974; 158:369-83. [PMID: 4823936 DOI: 10.1097/00005053-197405000-00008] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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143
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Angrist BM, Wilk S, Gershon S. The effect of probenecid and large dose amphetamine administration on cerebrospinal fluid homovanillic acid. Biol Psychiatry 1974; 8:113-4. [PMID: 4815338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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145
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146
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Shopsin B, Wilk S, Gershon S, Angrist B. Collaborative psychopharmacologic studies exploring the major CNS metabolites of norepinephrine in psychiatrict subjects: A report of progress. Life Sci 1973. [DOI: 10.1016/0024-3205(73)90394-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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147
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Webber MM, Wilk S, Pirruccello R, Aiken J. Telecommunication of images in the practice of diagnostic radiology. Radiology 1973; 109:71-4. [PMID: 4783130 DOI: 10.1148/109.1.71] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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148
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Wilk S, Orlowski M. The occurrence of free L-pyrrolidone carboxylic acid in body fluids and tissues. FEBS Lett 1973; 33:157-60. [PMID: 4580896 DOI: 10.1016/0014-5793(73)80182-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Shopsin B, Wilk S, Gershon S, Davis K, Suhl M. Cerebrospinal fluid MHPG. An assessment of norepinephrine metabolism in affective disorders. ARCHIVES OF GENERAL PSYCHIATRY 1973; 28:230-3. [PMID: 4684289 DOI: 10.1001/archpsyc.1973.01750320062010] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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