Publication Date: 1991
Neuropharmacology (00283908)(3)
The effects of the dihydropyridine calcium antagonist, nitrendipine and the calcium channel activator, Bay K 8644, have been compared on the anaesthetic, ataxic and anticonvulsant effects of benzodiazepines. Possible interactions between the peripheral benzodiazepine receptor antagonist, PK11195, and the classical benzodiazepines were also examined. Nitrendipine considerably potentiated the anaesthetic effects of benzodiazepines and increased their ataxic effects but had no effect on the anticonvulsant actions. Clonazepam did not produce anaesthesia, at doses up to 1 g kg-1 or when given with nitrendipine. When given alone, nitrendipine did not cause general anaesthesia. Nitrendipine did not appear to alter the metabolism of midazolam. The calcium channel activator, Bay K 8644, reduced the anaesthetic potency of midazolam and, when given alone, produced ataxia. It did not significantly alter central concentrations of midazolam. The "peripheral" benzodiazepine antagonist, PK11195, did not affect the ataxic or anaesthetic actions of benzodiazepines. These results suggest that dihydropyridine-sensitive calcium channels may be more important to the general anaesthetic than to the anticonvlsant actions of benzodiazepines. The "peripheral" benzodiazepine site did not appear to play a role in either of these properties. © 1991.
Publication Date: 1994
Pharmacology, Biochemistry and Behavior (00913057)(3)
We have shown previously that the dihydropyridine calcium channel antagonist nitrendipine, given chronically, prevents the development of ethanol tolerance and physical dependence. The present study examines the effects on barbiturate tolerance and physical dependence. Nitrendipine, given acutely during withdrawal, provided little protection against barbiturate withdrawal, as measured by convulsive behaviour on handling. When nitrendipine was given chronically concurrently with the barbiturate, a prolonged protection against the withdrawal syndrome was seen. Acute nitrendipine significantly increased the latency of seizures in response to the partial benzodiazepine inverse agonist FG7142 during barbiturate withdrawal, but there was no effect on the seizure incidence in response to bicuculline. Chronic treatment with nitrendipine did not alter the development of tolerance to the ataxic or general anaesthetic actions of barbiturates, but evidence was found of a possible interaction between nitrendipine and pentobarbitone, which may have been pharmacokinetic. The results suggest that neuronal calcium channels may be involved to some degree in the development of the changes responsible for barbiturate withdrawal, but to a less extent than found previously for ethanol dependence. © 1994.
Publication Date: 1994
British Journal of Pharmacology (00071188)(1)
The competitive antagonists at the N‐methyl‐d‐aspartate (NMDA) receptor, CGP39551 and CGP37849, protected against the barbiturate withdrawal syndrome in mice, as measured by ratings of convulsive behaviour on handling. The effective doses of these compounds were lower than those required to prevent seizures due to NMDA in naive animals; these were in turn lower than those needed to prevent the convulsive effects of the α‐aminobutyric acid (GABA) antagonist, bicuculline. The NMDA‐receptor antagonists did not alter the increase in the incidence of convulsions due to the GABAA antagonist, bicuculline, that is seen during barbiturate withdrawal, although the latencies to these convulsions during barbital withdrawal were significantly increased after CGP39551. Barbiturate withdrawal did not affect the convulsive actions of NMDA, whether measured by the incidence of convulsions or by intravenous infusion. The Bmax for [3H]‐dizocilpine ([3H]‐MK801) binding was significantly increased by chronic barbital treatment in cerebrocortical but not in hippocampal tissues, while the Kd remained unaltered in either case. At 1 h and 24 h after administration of a single dose of barbitone, the Bmax for [3H]‐dizocilpine binding was unaltered in cerebrocortical tissue. Acute addition of barbitone in vitro did not alter [3H]‐dizocilpine binding or the displacement of binding of thienylcyclohexylpyridine. 1994 British Pharmacological Society
Publication Date: 1995
Pharmacology, Biochemistry and Behavior (00913057)(1)
Tolerance occurred to the sedative actions of the competitive NMDA antagonists, CGP39551 and CGP37849, as measured by a decrease in spontaneous locomotor activity after 1 week or 2 weeks of administration, respectively, in studies using the TO strain of mice. Crosstolerance was seen between these compounds. When CGP37849 was given after 2 weeks treatment with CGP39551, an increase in locomotor activity was seen. Chronic barbiturate treatment, producing tolerance to the actions of pentobarbitone, did not affect the sedative properties of CGP39551 or CGP37849. Chronic treatment with CGP39551 did not alter the ataxic actions of pentobarbitone. Seven days of treatment with HA966 caused complete tolerance to its sedative actions, but no Crosstolerance was seen to pentobarbitone, CGP39551, or CGP37849. A small but significant decrease was seen in the convulsion thresholds to NMDA after 15 days of treatment with CGP39551, and a small significant increase in ratings of convulsive behavior after 16 days injections of CGP37849. No significant changes were found in either Bmax or Kd for [3H]-MK-801 binding in cerebrocortical tissue 24 h after the last chronic treatment with either of the NMDA antagonists. © 1994.
Gäken, J.A.,
Tavassoli, M.,
Gan, S.,
Vallian borujeni, S.,
Giddings, I.,
Darling, D.C.,
Galea-lauri, J.,
Thomas, M.G.,
Abedi, H.,
Schreiber, V. Publication Date: 1996
Journal of Virology (10985514)70(6)pp. 3992-4000
Integration of proviral DNA into the host cell genome is a characteristic feature of the retroviral life cycle. This process involves coordinate DNA strand break formation and rejoining reactions. The full details of the integration process are not yet fully understood. However, the endonuclease and DNA strand-joining activities of the virus-encoded integrase protein (IN) are thought to act in concert with other, as-yet-unidentified, endogenous nuclear components which are involved in the DNA repair process. The nuclear enzyme poly(ADP-ribose) polymerase (PARP), which is dependent on DNA strand breaks for its activity, is involved in the efficient repair of DNA strand breaks, and maintenance of genomic integrity, in nucleated eukaryotic cells. In the present work, we examine the possible involvement of PARP in the retroviral life cycle and demonstrate that inhibition of PARP activity, by any one of three independent mechanisms, blocks the infection of mammalian cells by recombinant retroviral vectors. This requirement for PARP activity appears to be restricted to processes involved in the integration of provirus into the host cell DNA. PARP inhibition does not affect viral entry into the host cell, reverse transcription of the viral RNA genome, postintegration synthesis of viral gene products, synthesis of the viral RNA genome, or the generation of infective virions. Therefore, efficient retroviral infection of mammalian cells is blocked by inhibition of PARP activity.
Arif, S.,
Vallian borujeni, S.,
Farzaneh, F.,
Zanone, M.M.,
James, S.L.,
Pietropaolo, M.,
Hettiarachchi, S.,
Vergani, D.,
Conway, G.S.,
Peakman, M. Publication Date: 1996
Journal of Clinical Endocrinology and Metabolism (0021972X)81(12)pp. 4439-4445
Autoantibodies directed against steroid hormone-producing cells (SCA) detectable by immunofluorescence are typically found in a small proportion of patients with premature ovarian failure (POF) as well as in other endocrine autoimmune diseases. The SCA pattern stains cells in the outer zones of the adrenal cortex, ovary, and testis. To identify the molecular target of SCA, an adrenal complementary DNA expression library was screened using SCA- positive serum, and the steroid enzyme 3β-hydroxysteroid dehydrogenase (3βHSD) was identified. Only 1 of 48 (2%) patients with idiopathic POF, not preselected for the presence of other autoimmune diseases, had SCA by immunofluorescence, whereas 10 of 48 (21%) had anti-3βHSD autoantibodies detectable by immunoblot using recombinant human enzyme compared with 6 of 115 (5%) control subjects (P = 0.002). Absorption of SCA-positive serum with recombinant human 3βHSD abolished the immunofluorescence pattern. We also examined the prevalence of anti-3βHSD autoantibodies in other endocrine autoimmune diseases. Two of 112 (2%) diabetic patients, but none of the thyroid or Addisonian patients, had SCA by immunofluorescence. Twenty-six (23%) diabetic subjects (P < 0.001 vs. controls), 3 of 18 thyroid patients (P > 0.05 vs. controls), and none of 4 Addisonian patients had anti-3βHSD autoantibodies. 3βHSD is the first steroid cell autoantigen defined at the molecular level to be associated with idiopathic POF occurring in the absence of other polyglandular diseases. Autoantibodies to 3βHSD in patients with other organ-specific autoimmune diseases indicate that the enzyme behaves as a typical target of polyendocrine autoimmunity. Anti-3βHSD autoantibodies in patients with POF may provide a marker of those subjects whose ovarian failure is autoimmune in origin and, as recent studies suggest, may be salvageable with glucocorticoid treatment.
Publication Date: 1997
Carcinogenesis (01433334)18(11)pp. 2063-2069
Our previous studies demonstrated that PML is a growth suppressor that suppresses oncogenic transformation of NIH/3T3 cells and rat embryo fibroblasts. PML is a nuclear matrix-associated phosphoprotein whose expression is regulated during the cell cycle. Disruption of PML function by t(15;17) in acute promyelocytic leukemia (APL) plays a critical role in leukemogenesis. To further study the role of PML in the control of cell growth, we have stably overexpressed PML protein in the HeLa cell line. This overexpression of PML significantly reduced the growth rate of HeLa cells and suppressed anchorage-independent growth in soft agar. We consequently investigated several parameters correlated with cell growth and cell cycle progression. We found that, in comparison with the parental HeLa cells, HeLa/PML stable clones showed proportionally more cells in G1 phase, fewer cells in S phase and about the same number in G2/M phase. The HeLa/PML clones showed a significantly longer doubling time as a result of a lengthening of the G1 phase. No effect on apoptosis was found in HeLa cells overexpressing PML. This observation indicates that PML suppresses cell growth by increasing cell cycle duration as a result of G1 elongation. To further understand the mechanism of the effect of PML on HeLa cells, expression of cell cycle-related proteins in HeLa/PML and parental HeLa cells was analyzed. We found that Rb phosphorylation was significantly reduced in PML stable clones. Expression of cyclin E, Cdk2 and p27 proteins was also significantly reduced. These studies indicate that PML affects cell cycle progression by mediating expression of several key proteins that normally control cell cycle progression. These results further extend our current understanding of PML function in human cells and its important role in cell cycle regulation.
Vallian borujeni, S.,
Gäken, J.A.,
Trayner, I.D.,
Gingold, E.B.,
Kouzarides, T.,
Chang k.-s., K.,
Farzaneh, F. Publication Date: 1997
Experimental Cell Research (10902422)237(2)pp. 371-382
Acute promyelocytic leukemia is characterized by the presence of a t(15; 17) chromosomal translocation which results in the expression of a chimeric gene product, PMLRARα, consisting of an N-terminal-truncated retinoic acid receptor-α fused to a C-terminal-truncated PML. Several structural features, and regions of homology to known transcription factors, suggest that PML may be involved in the regulation of gene expression. In this study we have analyzed the transcriptional regulatory activity of PML using chimeric GAL4/PML constructs and GAL4-responsive reporter plasmids. The data presented demonstrate that PML, when fused to the DNA-binding domain of GAL4 (GAL4/PML), inhibits transcription from GAL4-responsive promoters. The magnitude of this repression is cell type and promoter dependent, and deletion studies show that the putative coiled-coil and part of the serine- rich regions of PML are required for this activity. These regions are also shown to be responsible for the repression of transcription activity from the EGFR promoter. The data presented also demonstrate that GAL4/PML can recruit PMLRARα resulting in the retinoid-inducible transcriptional activation of a GAL4-responsive promoter, a function dependent on the presence of the coiled- coil region of PMLRARα.
Publication Date: 1998
Obstetrics and Gynecology (00297844)91(3)pp. 319-323
Objective: To determine whether the mechanism for the retention of interstitial fluid in trisomy 21 fetuses presenting with nuchal translucency at 10-14 weeks' gestation is an alteration in the composition of collagen type VI, which is normally a triple helix formed of three single chains, α1, α2, and α3. The genes responsible for the α1 and α2 chains, COL6A1 and COL6A2, are located on chromosome 21 and therefore may be overexpressed in trisomy 21, whereas COL6A3 is located in chromosome 2. Methods: Skin tissue was obtained after termination of pregnancy at 11-16 weeks' gestation in five fetuses with trisomy 21 and five normal controls. Total RNA was extracted and the steady-state levels of COL6A1 and COL6A3 mRNA expression of the gene transcripts were determined. Additionally, the distribution of collagen type VI in the skin of trisomy 21 and normal fetuses was analyzed using an immunohistochemical method. Results: The ratio of the normalized densitometric scores for the mRNA expression of COL6A1 to COL6A3 in the skin of trisomy 21 fetuses was twice as high as in normal fetuses. Immunohistochemistry demonstrated that in trisomy 21 fetuses collagen type VI formed a dense network extending from the epidermal basement membrane to the subcutis, whereas in normal fetuses dense staining was confined to the upper region of the dermis. Conclusion: The distribution for collagen type VI is different from normal in the skin of trisomy 21 fetuses, and there is overexpression of COL6A1 compared with COL6A3.
Vallian borujeni, S.,
Gäken, J.A.,
Gingold, E.B.,
Kouzarides, T.,
Chang k.-s., K.,
Farzaneh, F. Publication Date: 1998
Oncogene (14765594)16(22)pp. 2843-2853
The growth and transformation suppressor function of promyelocytic leukemia (PML) protein are disrupted in acute promyelocytic leukemia (APL) as a result of its fusion to the RARα gene by t(15;17) translocation. There is significant sequence homology between the dimerization domain of PML and the Fos family of proteins, which imply that PML may be involved in AP-1 activity. Here we show that PML can cooperate with Fos to stimulate its AP-1-mediated transcriptional activity. Cotransfection of PML, with GAL4/Fos strongly induced Fos-mediated activation of GAL4-responsive reporters, indicating a functional interaction between Fos and PML in vivo. Deletion analysis of Fos and PML demonstrated that the intact C-terminal domain of Fos (containing the dimerization domain), and the RING-finger, B1 box and nuclear localization domains of PML are involved in the cooperative activity of Fos and PML. Immunoprecipitation and electrophoretic mobility shift assay showed that PML is associated with the AP-1 complex. PMLRARα was also found to enhance the transcriptional activity of GAL4/Fos. The addition of retinoic acid abrogated the PMLRARα, but not PML-induced stimulation of GAL4/Fos activity in a dose-dependent manner. This study demonstrated that PML is involved in the AP-1 complex and can modulate Fos-mediated transcriptional activity, which may contribute to its growth suppressor function.
Publication Date: 1998
Oncogene (14765594)16(14)pp. 1839-1849
Our previous studies demonstrated that the promyelocytic leukemia gene, PML which involved in the 15;17 translocation in acute promyelocytic leukemia (APL) is a growth and transformation suppressor. In this study, recombinant PML adenovirus, Ad-PML was constructed and used to infect human breast cancer cells in vitro and in vivo, the anti-oncogenic function of PML and its mechanism of growth suppressing effect in breast cancer cells were examined. We showed that Ad-PML effectively infected the MCF-7 and SK-BR-3 cells. A high level of PML protein was expressed within 24 h post-infection and a detectable level remained at day 16. Ad-PML significantly suppressed the growth rate, clonogenicity, and tumorigenicity of breast cancer cells. Intratumoral injections of MCF-7-induced tumors by high titer Ad-PML suppressed tumor growth in nude K mice by about 80%. The injection sites expressed high level of PML and associated with a massive apoptotic cell death. To elucidate the molecular mechanism of PML's growth suppressing function, we examined the effect of Ad-PML on cell cycle distribution in MCF-7 and SK-BR-3 cells. We found that Ad-PML infection caused a cell cycle arrest at the G1 phase. We further showed that G1 arrest of MCF-7 cells is associated with a significant decrease in cyclin D1 and CDK2. An increased expression of p53, p21 and cyclin E was found. The Rb protein became predominantly hypophosphorylated 48 h post-infection. These findings indicate that PML exerts its growth suppressing effects by modulating several key G1 regulatory proteins. Our study provides important insight into the mechanism of tumor suppressing function of PML and suggests a potential application of Ad-PML in human cancer gene therapy.
Publication Date: 1998
Molecular and Cellular Biology (02707306)18(12)pp. 7147-7156
The promyelocytic leukemia protein (PML) is a nuclear phosphoprotein with growth- and transformation-suppressing ability. Having previously shown it to be a transcriptional repressor of the epidermal growth factor receptor (EGFR) gene promoter, we have now shown that PML's repression of EGFR transcription is caused by inhibition of EGFR's Sp1-dependent activity. On functional analysis, the repressive effect of PML was mapped to a 150-hp element (the sequences between -150 and -16, relative to the ATG initiation site) of the promoter. Transient transfection assays with Sp1-negative Drosophila melanogaster SL2 cells showed that the transcription of this region was regulated by Sp1 and that the Sp1-dependent activity of the promoter was suppressed by PML in a dose-dependent manner. Coimmunoprecipitation and mammalian two-hybrid assays demonstrated that PML and Sp1 were associated in vivo. In vitro binding by means of the glutathione S-transferase (GST) pull-down assay, using the full-length and truncated GST- Sp1 proteins and in vitro-translated PML, showed that PML and Sp1 directly interacted and that the C-terminal (DNA-binding) region of Sp1 and the coiled-coil (dimerization) domain of PML were essential for this interaction. Analysis of the effects of PML on Sp1 DNA binding by electrophoretic mobility shift assay (EMSA) showed that PML could specifically disrupt the binding of Sp1 to DNA. Furthermore, cotransfection of PML specifically repressed Sp1, but not the E2F1-mediated activity of the dihydrofolate reductase promoter. Together, these data suggest that the association of PML and Sp1 represents a novel mechanism for negative regulation of EGFR and other Sp1 target promoters.
Publication Date: 1999
Iranian Journal Of Medical Sciences (02530716)(3-4)
Background: The cAMP signal transduction systems are known to play a critical role in the acute and chronic effects of ethanol and other drugs of abuse. Objective: To investigate the role of protein kinase C (PKC) in the action of ethanol on platelets and human erythroleukemia (HEL) cells. Methods: HEL, HEK 293 cells [transfected with AC type VII(AC7)] and platelets were used to study the effects of ethanol. cAMP accumulation assay was used to determine the percentage conversion of [3H]ATP into [3H]cAMP. Each fraction was separated through sequential chromatography and the radioactive material was then quantified using a liquid scintillation counter. Results: Ethanol enhanced the PGE1-stimulated AC activity in HEL cells. The percent enhancement of cAMP accumulation by 200 mM ethanol was similar in HEL cells, platelets and HEK 293 cells transfected with AC7. When combined with PDBu, 200 mM ethanol further enhanced the PDBu stimulation of AC activity suggesting a separate mechanism by which ethanol and PDBu exert their effects on the AC. Pretreatment of the cells with staurosporine and chelerythrine significantly blocked the PDBu-and/or ethanol-enhancement of cAMP accumulation. Conclusion: These results indicate a clear role for PKC in the action of ethanol on AC in platelets.
Publication Date: 1999
European Journal of Pharmacology (00142999)(2-3)
Chronic barbital treatment significant increased the net K+-stimulated uptake of 45Ca2+ in cerebrocortical synaptosomal preparations, 24 h after withdrawal from chronic barbital administration. Basal uptake was not significantly changed. Hippocampal synaptosomal preparations showed a similar pattern, but the increase was not significant. The synaptosomal Ca2+ uptake was not affected by incubation with the dihydropyridine Ca2+ channel antagonist, nitrendipine, in controls or after chronic barbital treatment. Acute administration of a single dose of barbital did not alter the basal or stimulated uptake of 45Ca2+ in cortical synaptosomes, when this was measured 36 h after the barbital administration. Hippocampal slices prepared 24 h after withdrawal from chronic barbital treatment showed a significant increase in K+-stimulated uptake of 45Ca2+, and the basal uptake was significantly decreased. Both changes were prevented by nitrendipine. An increase in the density of dihydropyridine-sensitive binding sites was found in the cerebral cortex. The results indicate that both dihydropyridine-sensitive and insensitive neuronal Ca2+ channels are altered by chronic barbiturate treatment. These changes may be involved in physical dependence on barbiturates. Copyright (C) 1999 Elsevier Science B.V.
Publication Date: 1999
Alcoholism: Clinical and Experimental Research (01456008)(1)
Ethanol is known to enhance the activity of adenylyl cyclase (AC) in a number of cells and tissues. Recent work has suggested that the various isoforms of AC show differential sensitivity to ethanol, with Type VII AC being most sensitive. However, the mechanism of action of ethanol is unclear. In the present work, we investigated the effect of ethanol on AC activity in the human erythroleukemia (HEL) cell line, platelets, and AC VII-transfected HEK 293 cells. The HEL cells contain abundant amounts of mRNA for Type VII AC. We found that both ethanol and phorbol dibutyrate (PDBu) treatment enhanced agonist (prostaglandin E1; PGE1)-stimulated AC activity in HEL cells, as well as in platelets and HEK 293 cells transfected with AC VII. Inhibitors of protein kinase C (PKC) blocked the stimulatory effects of both ethanol and PDBu. However, the effects of ethanol and PDBu on AC activity were additive, suggesting that the mechanisms of action of ethanol and PDBu were not identical. Furthermore, a 30-min exposure of HEL cells to ethanol attenuated (desensitized) the ability of ethanol, but not PDBu, to enhance agonist-activated AC activity. On the other hand, a 30-min pretreatment with PDBu attenuated the AC response to the phorbol ester, but not to ethanol; but, after a 20 hr preincubation with phorbol ester, the ability of both PDBu and ethanol to enhance prostaglandin E1-stimulated AC activity was completely eliminated. Finally, pretreatment of HEL cells with pertussis toxin blocked the effect of PDBu, but not ethanol, on AC activity. The results support the involvement of phorbol ester-sensitive PKC(s) in ethanol's enhancement of agonist-activated activity of AC in HEL cells, but suggest that the mechanism of ethanol's action is different from that of PDBu. The findings with pertussis toxin suggest that PDBu activation of PKC(s) may affect AC activity through phosphorylation of a G(i) protein, whereas ethanol may act by promoting phosphorylation of a different substrate (e.g., AC VII).
Publication Date: 2000
American Journal of Hematology (03618609)65(3)pp. 192-195
Sickle cell anemia is not considered to be a significant disease in Iran, although the sickle cell trait is estimated to have a high incidence in the Southern provinces. Since 1977, when the presence of a mild sickle cell anemia was reported in this country, there have been no further investigations published giving precise data on the incidence and origins of the sickle cell mutation in Iran. We report here the finding of patients with the sickle cell trait, sickle cell anemia, and sickle-β thalassemia in Central Iran. A survey of 300 individuals from a village in Southeast Esfahan revealed an incidence of the sickle cell trait of 8.33%. 'Cascade screening' enabled 96 relatives in four surrounding villages to be tested, and the at-risk couples were offered counseling as a 'sickle cell control program.' The hematological indices and HbF levels of the affected patients were determined. The HbF levels were unusually high, ranging from 18% to 41.4%, and SS patients with the highest levels were asymptomatic. Linkage analysis revealed the β(s) gene haplotype in this population to be the Indian-Arab haplotype. (C) 2000 Wiley-Liss, Inc.
Publication Date: 2001
European Journal of Pharmacology (00142999)(1)
Characteristic changes of platelet membrane adenylyl cyclase activity have been described in men with alcoholism. We studied the occurrence of these changes in human erythroleukemia (HEL) cells after chronic ethanol treatment. Chronic treatment of the HEL cell with ethanol (50 or 100 mM) for 48 h resulted in significant reduction of prostaglandin E1-stimulated adenylyl cyclase activity. The acute ethanol (200 mM, 5 min) enhancement of adenylyl cyclase activity was significantly reduced after chronic ethanol treatment. We also observed a reduction in phorbol-12,13-dibutyrate (PDB) enhancement of prostaglandin E1-stimulation after chronic ethanol treatment. Chronic ethanol treatment (50 or 100 mM) reduced the activity of adenylyl cyclase in response to stimulation by acute ethanol to a greater extent than that of after acute PDB. The increase in cAMP formation by ethanol and PDB was only evident when prostaglandin E1 was present and under basal conditions (when no stimulatory agent was present) ethanol up to 200 mM, and PDB up to 1 M, had no significant effect on adenylyl cyclase activity. The reduced capacity of ethanol and/or PDB to stimulate adenylyl cyclase activity after chronic ethanol treatment suggests the involvement of a common denominator in the action of ethanol and PDB. © 2001 Elsevier Science B.V. All rights reserved.
Publication Date: 2001
Enzyme and Microbial Technology (18790909)29(8-9)pp. 554-559
In the present study, irreversible thermoinactivation of holo- and apo-yeast alcohol dehydrogenase (YADH, EC 1.1.1.1) and protection by sugars (mannitol, sorbitol, sucrose and trehalose) were investigated at 50°C and pH 7.8. The apo-protein was obtained by removing the structural zinc with the catalytic zinc remaining on the enzyme. Thiol group oxidation, aggregation and deamidation were examined. Hypochlorous acid and cupric chloride were used in relation to thiol group oxidation. Zn2+ mobilization was measured spectrophotometrically using the metallochromic indicator 4-(2-pyridylazo)resorcinol (PAR). The presence of sugars provided significant protection against all the three deleterious processes. It is concluded that use of sugars may provide an effective approach for stabilization of holo- and apo-YADH via alteration of protein microenvironment. © 2001 Elsevier Science Inc. All rights reserved.
Wu w.-s., ,
Vallian borujeni, S.,
Seto e., ,
Yang w.-m., ,
Edmondson d., ,
Roth s., ,
Chang k.-s., K. Publication Date: 2001
Molecular and Cellular Biology (02707306)21(7)pp. 2259-2268
The growth suppressor promyelocytic leukemia protein (PML) is disrupted by the chromosomal translocation t(15;17) in acute promyelocytic leukemia (APL). PML plays a key role in multiple pathways of apoptosis and regulates cell cycle progression. The present study demonstrates that PML represses transcription by functionally and physically interacting with histone deacetylase (HDAC). Transcriptional repression mediated by PML can be inhibited by trichostatin A, a specific inhibitor of HDAC. PML coimmunoprecipitates a significant level of HDAC activity in several cell lines. PML is associated with HDAC in vivo and directly interacts with HDAC in vitro. The fusion protein PML-RARα encoded by the t(15;17) breakpoint interacts with HDAC poorly. PML interacts with all three isoforms of HDAC through specific domains, and its expression deacetylates histone H3 in vivo. Together, the results of our study show that PML modulates histone deacetylation and that loss of this function in APL alters chromatin remodeling and gene expression. This event may contribute to the development of leukemia.
Publication Date: 2002
International Journal of Biochemistry and Cell Biology (13572725)34(2)pp. 169-175
A comparative study was performed regarding the catalytic activity and stability of two related enzymes (thermophilic alcohol dehydrogenase from Thermoanaerobacter brockii and its mesophilic counterpart from yeast) in the presence of a number of miscible and immiscible organic solvents. The study was performed in view of the practical usefulness of organic solvents for alcohol dehydrogenases which have been shown to catalyse a variety of industrially-important dehydrogenation reactions. A number of organic solvents of different physicochemical characteristics were used and substantial stabilization was achieved. The non-polar solvents utilized showed the ability to enhance thermal stability of both proteins. Protection against thermal denaturation was especially pronounced by n-dodecane, the solvent with the highest log P used in the present study. Dimethylformamide and dioxane, employed as two miscible organic solvents, showed the ability to cause substrate inhibition and changes in protein conformation as indicated by kinetic and fluorescence studies. A higher resistance of the thermophilic protein to the deleterious effect of pyridine and thermostabilization of the mesophilic enzyme by non-polar solvents are especially emphasized. Combined differences in protein structure and nature of organic solvents are suggested to explain the differences in stability and catalytic activity observed in the present investigation. © 2002 Published by Elsevier Science Ltd.
Publication Date: 2003
Biomass and Bioenergy (09619534)25(4)pp. 423-426
A Gram-negative bacterium was isolated from corn root. This isolate is ellipsoidal to rod-shaped and slightly curved. The size of bacterium is 0.6 × (1 - 4) nm and occurring singly, in pairs or in chains. The isolated strain reduces nitrate, oxidizes ethanol to acetic acid, and hydrolyses starch and cellulose. The maximum amylase and Cellulase activities are 20 and 5.5 u ml-1, respectively. In addition, the isolate fixes nitrogen and has a good growth on the media without any nitrogen sources. A nitrogen fixation negative strain (Nif-) was obtained from the isolate by UV mutation. This mutant strain Nif- dose not grow on the media without nitrogen sources, but it has cellulase activities. © 2003 Elsevier Ltd. All rights reserved.
Publication Date: 2003
Journal of Ethnopharmacology (03788741)(2-3)
Interest in alternative medicine and plant-derived medications that affect the "mind" is growing. The aim of the present study was to investigate the effects of a hydroalcoholic extract and essential oil of Stachys lavanduifolia Vahl on the elevated plus-maze (EPM) model of anxiety. The Stachys lavandulifolia extract or its essential oil was administered intraperitoneally to male TO mice, at various doses, 30min before the behavioral evaluation. The extract of Stachys lavandulifolia at the dose of 100mg/kg increased the percentage of time spent and the percentage of arm entries in the open arms of the EPM and decreased the percentage of time spent and the percentage of arm entries in the closed arms of the EPM. The plant extract at doses lower than 100mg/kg had no significant effects on any of the parameters measured on the EPM. This dose of the plant extract prolonged the ketamine-induced sleeping time, and decreased the locomotor activity in mice. These results suggested that the extract of Stachys lavandulifolia possessed anxiolytic effect with relatively lower sedative activity than diazepam. The essential oil of Stachys lavandulifolia, however, at doses of up to 100mg/kg did not have any significant effects on the mice behaviour on the EPM. © 2003 Elsevier Ireland Ltd. All rights reserved.
Publication Date: 2003
Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis (13861964)526(1-2)pp. 45-52
Phenylalanine hydroxylase (PAH) deficiency is caused by mutations in the PAH gene (12q22-q24) resulting in a primary deficiency of the PAH enzyme activity, intolerance to the dietary intake of phenylalanine (Phe) and production of the phenylketonuria (PKU) disease. To date there have been no reports on the molecular analysis of PKU in Iranian population. In this study, the states of the PKU disease in terms of prevalence and mutation spectrum among patients reside in the institutions for mentally retarded in Isfahan was investigated. In the first step, 611 out of 1541 patients with PKU phenotype or severe mental retardation were screened for the PKU disease using the Guthrie bacterial inhibition assay (GBIA) followed by HPLC. Among the patients screened 34 (5.56%) were found positive with abnormal serum Phe of above 7mg/dl. In the next step, the presence of 18 common mutations of the PAH gene in 26 of the patients with classical PKU (serum Phe above 20mg/dl) was investigated, using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Of the 52 independent mutant alleles that were analyzed, 34 (65.38%) were genotyped showing 8 mutations as follows: R252W (15.38%), Q232Q (13.46%), R261Q (7.69%), delL364 (7.69%), IVS10-11g > a (5.77%), L333F (5.77%), V245V (5.77%) and S67P (3.85%). The results from this study may serve as a reference to analyze the PKU mutations in other part of Iran, and to establish diagnostic tests for carrier detection and prenatal diagnosis of the PKU disease in Iranian population. © 2003 Elsevier Science B.V. All rights reserved.
Publication Date: 2004
Iranian Journal of Pharmaceutical Research (17350328)(2)
There is growing evidence indicating that neuronal calcium channels play an important role in the mechanism of morphine dependence. In this study, the effects of acute and chronic administration of nitrendipine on naloxone precipitated morphine withdrawal signs were investigated. Mice were rendered dependent to morphine by subcutaneous injection of morphine over a period of 5 days. In chronic studies, nitrendipine (25 and 50 mg/kg, i.p.), or vehicle injections were given once a day during the morphine treatment, and the last injection of nitrendipine was given 24 h before the morphine withdrawal. For acute studies, nitrendipine (25 and 50 mg/kg, i.p.) was given 1 h after the last dose of morphine (1 h before naloxone). A single injection of nitrendipine at 25 mg/kg was ineffective in blocking most signs of morphine withdrawal, however, at 50 mg/kg nitrendipine blocked signs such as hair raising, sniffing, diarrhea and number of jumping. The concurrent injections of nitrendipine with morphine prevented most signs of morphine withdrawal. In agreement with previous findings, these results suggest that alterations in voltage-sensitive calcium channels play a role in the adaptations that occur on chronic treatment with morphine. © 2004 by School of Pharmacy.
Publication Date: 2004
Fitoterapia (0367326X)(5)
The ethanolic extract of Echium amoenum flowers at the dose of 50 mg/kg increased the percentage of time-spent and the percentage of arm entries in the open arms of the elevated plus-maze (EPM) and decreased the percentage of time-spent in the closed arms of EPM. Moreover, it prolonged the ketamine-induced latency to sleep but had no significant effects on total sleeping time induced by ketamine. Also, the locomotor activity was affected but not to the same extent as observed for diazepam. These results suggested that the extract of E. amoenum seems to possess anxiolytic effect with lower sedative activity than that of diazepam. © 2004 Elsevier B.V. All rights reserved.
Publication Date: 2004
Iranian Journal of Pharmaceutical Research (17350328)(3)
Effect of Otostegia persica on naloxone-induced morphine withdrawal syndrome was studied in male mice. Dependence was induced using daily subcutaneous injections of morphine for three days. Morphine was injected to mice at doses of 30 and 45mg/kg on day 1 and 60 and 90mg/kg on day 2 (8:00 am and 6:00 pm). On day 3, morphine (90mg/kg) was injected 1h before oral administration and 1.5h before intraperitoneal (i.p.) injection of hydroalcoholic and hexane extracts of the plant. Naloxone was injected (5mg/kg, i.p.) 2h after the final dose of morphine and the withdrawal signs including jumping, rearing, diarrhoea, piloerection, tremor and ptosis were recorded during a period of 30 minutes. While oral and i.p. administration of hydroalcoholic extract reduced the number of jumping and rearing, the hexane extract could not exert any significant change. Also the hydroalcoholic extract (1500mg/kg) significantly (p<0.05) reduced diarrhoea, piloerection, tremor and ptosis. The hexane extract only significantly (p<0.05 ) inhibited diarrhoea. Results of this study indicated that the extract of Otostegia persica contained component(s) that alleviate morphine withdrawal syndrome and the responsible constituent(s) is(are) found in polar fraction since the hexane extract had only a negligible effect. © 2004 by School of Pharmacy Shaheed Beheshti University of Medical Sciences and Health Services.
Publication Date: 2004
African Journal of Biotechnology (16845315)3(6)pp. 330-333
Two Azotobacter strains were isolated from alkaline and acid soils. The production of alginate and exopolymer from these two strains showed that, strain AC2 produced high polymer in 2% beet molasses or 1% sucrose broth and addition of nitrogen sources (yeast extract) reduced production of this polymer. The optimum condition for production of maximum polymer production (7.5 mg/ml) was at 200 rpm shaking, pH 7 without addition of nitrogen sources. The production of polymer was reduced at pH 4. The polymer adsorbed Cu, Zn, and Fe, at 15.5, 20 and 25 mg, respectively. © 2004 Academic Journals.
