Browsing by Author "LABARCA, R"

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    CLINICAL AND BIOCHEMICAL EFFECTS OF VERAPAMIL ADMINISTRATION TO SCHIZOPHRENIC-PATIENTS
    (1987) PICKAR, D; WOLKOWITZ, OM; DORAN, AR; LABARCA, R; ROY, A; BREIER, A; NARANG, PK
    We administered verapamil hydrochloride, a calcium channel antagonist, to seven chronically ill schizophrenic patients for five weeks under double-blind, placebo-controlled conditions. No therapeutic effect was noted. Worsening in hostile and uncooperative behaviors and a syndrome of heightened emotional tone was observed during verapamil treatment and during the postverapamil placebo period. Verapamil produced significant increases in cerebrospinal fluid (CSF) and plasma levels of homovanillic acid and in plasma level of prolactin, as well as significant decreases in plasma levels of 3-methoxy-4-hydroxyphenethyleneglycol. Verapamil and its active metabolite, norverapamil, were partitioned into CSF with CSF/plasma ratios of 0.06 and 0.04, respectively. The lack of therapeutic effects of verapamil of schizophrenic patients differ from earlier reports of its usefulness in treating manic patients. The biochemical and clinical data from our study suggest the possibility that verapamil exerts behaviorally relevant central nervous system activity in schizophrenic patients.
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    NEUROTRANSMITTER-RELATED ENZYME ACETYLCHOLINESTERASE IN JUVENILES OF CONCHOLEPAS-CONCHOLEPAS (MOLLUSCA, GASTROPODA, MURICIDAE)
    (1990) GONZALEZ, M; PERELMAN, A; FUENTES, ME; CASTILLA, JC; LABARCA, R; BRANDAN, E; GONZALEZPLAZA, R; INESTROSA, NC
    With the aim of understanding the organization of the nervous systemn in the Prosobranchia gastropod Concholepas concholepas, we studied the properties, specificity, sedimentation coefficient, and solubility of the cholinergic enzyme, acetylcholinesterase (AChE). It was found that 95% of the esterase was inhibited by BW284c51 dibromide but not by iso-OMPA, which is consistent with the specificity of AChE. The calculated Km 0.22 mM is eight to ten times higher than are the Kms for AChE of other invertebrates and similar to the values reported for fish and vertebrates. The AChE shows a maximal activity around 22.degree. C, has a glycoprotein character and presents sedimentation coefficients of 6.5 S and 10.5 S. Most of this AChE activity is soluble under low ionic strength conditions; however, the enzyme aggregates in the absence of detergents. In conclusion, our evidence indicates the presence of a well-recognized molecular marker that could be useful for the study of the development of Concholepas concholepas.