P-gp activity is a critical resistance factor against AVE9633 and DM4 cytotoxicity in leukaemia cell lines, but not a major mechanism of chemoresistance in cells from acute myeloid leukaemia patients. (25/95)

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Effects of hypoxia-ischemia and MK-801 treatment on the binding of a phencyclidine analogue in the developing rat brain. (26/95)

The phencyclidine analogue [3H](1-[2-thienyl]cyclohexyl)piperidine (3H-TCP) binds to the ion channel associated with the N-methyl-D-aspartate receptor channel complex. In vitro autoradiography indicates that the distribution of 3H-TCP binding in brain closely parallels that of [3H]glutamate binding to the N-methyl-D-aspartate receptor. In nine 7-day-old rats, an acute focal hypoxic-ischemic insult produced by unilateral carotid artery ligation and subsequent exposure to 8% oxygen acutely reduced 3H-TCP binding ipsilateral to the ligation by 30% in the CA1, by 27% in the CA3, by 26% in the dentate gyrus, and by 17% in the striatum compared with values from the contralateral hemisphere. In 10 littermates that received 1 mg/kg of the neuroprotective noncompetitive N-methyl-D-aspartate antagonist MK-801 immediately before hypoxic exposure, the regional distribution of 3H-TCP binding in hypoxic-ischemic brain was relatively preserved and there were no interhemispheric asymmetries in 3H-TCP binding densities. In addition, in three unoperated rats decapitated 24 hours after MK-801 treatment, 3H-TCP binding was reduced by 15-35%; similar bilateral suppression of 3H-TCP binding was detected in MK-801-treated ligates. Our data indicate that 3H-TCP autoradiography can be used to assay the efficacy of neuroprotective agents in this experimental model of perinatal stroke.  (+info)

Protective effects of the glutamate antagonist MK-801 on pyrithiamine-induced lesions and amino acid changes in rat brain. (27/95)

An acute bout of pyrithiamine-induced thiamine deficiency (PTD) produces pathologic lesions within thalamus, mammillary body, and periventricular regions of rat brain. The biological bases for these pathologic changes and their selective distribution within the brain are unclear. The type of tissue damage observed within the thalamus of PTD rats closely resembles that observed following anoxic-ischemic insults and suggests the involvement of excitotoxic amino acids in its pathogenesis. The effects of the N-methyl-D-aspartate receptor antagonist MK-801 (3 mg/kg, i. p.) on brain lesions and amino acid changes have been assessed in rats killed during the late acute stages of PTD. A marked loss of neurons within midline intralaminar nuclei and the posterior nuclear group of the thalamus were observed in the early acute stage of PTD treatment. In the late acute stage, these changes were present throughout the entire thalamus and extended caudally to the periacqueductal gray and mesencephalic tegmentum. Hemorrhagic lesions were observed only in the late acute group and were the primary lesion within the mammillary body and medial and lateral geniculates. No pathologic changes were observed in hippocampus, amygdala, and cortex. MK-801 administered during the late stages resulted in a marked attenuation of necrotic damage to thalamus and periacqueductal gray and a reduction in the number and size of hemorrhagic lesions. Significant reductions of aspartate and glutamate and increases of glycine were observed in 5 regions of thalamus, the hippocampus, hypothalamus, and mammillary bodies of both the early and late acute PTD groups. Levels of GABA and taurine in caudal areas were significantly elevated in the early acute stage but were unchanged from controls in the late acute group. These amino acid changes were reduced in the MK-801 treated late acute group. These observations suggest that NMDA receptors are involved the pathogenesis of PTD-induced brain lesions and that nuclei of the intralaminar and posterior nuclear groups are most vulnerable to PTD effects.  (+info)

Amurensin G, a potent natural SIRT1 inhibitor, rescues doxorubicin responsiveness via down-regulation of multidrug resistance 1. (28/95)

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Zosuquidar, a novel modulator of P-glycoprotein, does not improve the outcome of older patients with newly diagnosed acute myeloid leukemia: a randomized, placebo-controlled trial of the Eastern Cooperative Oncology Group 3999. (29/95)

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Attenuation of intestinal absorption by major efflux transporters: quantitative tools and strategies using a Caco-2 model. (30/95)

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Endoxifen, the active metabolite of tamoxifen, is a substrate of the efflux transporter P-glycoprotein (multidrug resistance 1). (31/95)

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Amineptine treatment of persistent catatonic symptoms in schizophrenia: a controlled study. (32/95)

BACKGROUND: Data on the treatment response of enduring catatonic phenomena accompanying chronic schizophrenia are few and far between. The aim of this study was to explore the therapeutic effects of add-on amineptine, a dopamine agonist antidepressant in chronic catatonia occurring in schizophrenia. METHOD: Fifteen subjects with DSM-IV schizophrenia presenting with persistent catatonic features underwent a 15-week, double-blind, placebo-controlled cross-over trial; they were treated for 6 weeks each with amineptine and a placebo, with a 3-week wash-out period in between. The primary outcome measures were the sum scores of the Bush-Francis Catatonia Rating Scale and the Modified Rogers Scale. Changes in other aspects of psychopathology and extrapyramidal side effects (EPS) constituted the secondary outcome measures. RESULTS: Amineptine augmentation of antipsychotic treatment had no appreciable effect on either of the catatonia ratings. Apart from a statistically significant but clinically negligible improvement in the negative symptom scores, there were no changes in the psychopathology and EPS ratings. CONCLUSION: The lack of a therapeutic effect of the dopamine agonist amineptine on persistent catatonic signs and symptoms suggests that the dopamine system may not have a decisive role in the pathophysiology of chronic catatonic syndrome arising in the context of schizophrenia.  (+info)