Effects of purine nucleotide administration on purine nucleotide metabolism in brains of heroin-dependent rats

ABSTRACT Heroin is known to enhance catabolism and inhibit anabolism of purine nucleotides, leading to purine nucleotide deficiencies in rat brains. Here, we determined the effect of exogenous purine nucleotide administration on purine nucleotide metabolism in the brains of heroin-dependent rats. Heroin was administrated in increasing doses for 9 consecutive days to induce addiction, and the biochemical changes associated with heroin and purine nucleotide administration were compared among the treated groups. HPLC was performed to detect the absolute concentrations of purine nucleotides in the rat brain cortices. The enzymatic activities of adenosine deaminase (ADA) and xanthine oxidase (XO) in the treated rat cortices were analyzed, and qRT-PCR was performed to determine the relative expression of ADA, XO, adenine phosphoribosyl transferase (APRT), hypoxanthine-guaninephosphoribosyl transferase (HGPRT), and adenosine kinase (AK). Heroin increased the enzymatic activity of ADA and XO, and up-regulated the transcription of ADA and XO. Alternatively, heroin decreased the transcription of AK, APRT, and HGPRT in the rat cortices. Furthermore, purine nucleotide administration alleviated the effect of heroin on purine nucleotide content, activity of essential purine nucleotide metabolic enzymes, and transcript levels of these genes. Our findings therefore represent a novel, putative approach to the treatment of heroin addiction.

Seguridad y eficacia del regimen: clofarabina + ciclofosfamida + etoposido en pacientes pediatricos con leucemias linfocitica aguda recurrente y/o refractaria a dos lienas de tratamiento / Safety and efficacy of the regimen: clofarabine + cyclophosphamide + etoposide in pediatric patients with recurrent and / or refractory acute lymphocytic leukemias to two treatment

IINTRODUCCIÓN: Antecedentes: El presente informe expone la evaluación del medicamento clofarabina respecto a su uso en combinación con ciclofosfamida y etopósido, en pacientes menores de 21 años con leucemia leucemia linfocítica aguda recurrente y/o refractaria a dos líneas de tratamiento con donante disponible. Aspectos Generales: La leucemia aguda es el cáncer más frecuente el la población pediátrica, comprendiendo aproximadamente el 30% de todas las enfermedades malignas pedátricas. De todas las leucemias, la leucemia linfoblástica aguda (LLA) ocurre cinco veces más frecuentemente que la leucemia mieloide aguda (LMA). Tecnología Sanitaria de Interés: Clofarabina: La clofarabina es un análogo nucleósido purínico de segunbda generación. Después de varias fosforilaciones consecutivas, la clofarabina es convertida en su metabolito activo trifosfato. Se cree que la actividad anticancerígena de clofarabina trifosfato se debe a tres mecanismos: (1) la incorporación del trifosfato en el DNA por intermedio de la DNA polimerasa que conduce a sua inhibición resultadno en la detención de la elongación del DNA y/o la reparación o sínstesis del DNA, (2) inhibición de la ribo nucleótido reductasa con reducción del pool de trifosfato deoxínucleotido (dNTP), e (3) inducción de la apoptosis a través de la acción directa e indirecta en la mitocondria produciendo la liberación de citocromo C y otros factores proapottóticos. METODOLOGÍA: Estratégia de Búsqueda: Se realizó una búsqueda con respecto a la eficacia y seguridad del esquema de clofarabina + ciclofosfamida + etopósido para el tratamiento de la leucemia linfocítica aguda en pacientes pediátricos con dos o más recaídas y/o recurriecias a líneas de quimioterapia en las bases de datos de Ovid Medline y Tripdatabase. También se hizo una búsqueda adicional en www.clinicaltrials.gov, para poder identificar ensayos en desarrollo. RESULTADOS: Se realizó la búsqueda bibliográfica y de la evidencia científica para el sustento del uso del esquema combinado de clofarabina con etocósido y ciclofosfamida como tratamiento de reinducción en pacientes pediátricos con LLA y con 2 o más recaídas o resistencias al tratamiento. CONCLUSIONES: En la presente evaluación de tecnología sanitaria la evidencia es escasa respecto a la eficacia y seguridad del esquema triple de clofarabina, etopósido y ciclofosfamida en el tratamiento de pacientes pediátricos con LLA y con recaídas y/o resistencia. Se identificaron dos ensayos fase II no comparativos y cuatro estudios de series de casos, que sugieren que el esquema triple pueden lograr la remissión general (RC y RCp) en cerca de la mitad de los pacientes tratados. Sin embargo, debido a las limitaciones metodológicas de los estudios, esta evidencia es de baja calidad, significando que la confianza en los estimados es aún muy baja respecto a pacientes peidátricos con LLA que requieren tratamiento de rescate, en quienes es un desafio realizar ensayos clínicos fase III. El Instituto de Evaluación de Tecnologías en Salud e Investigación-IETSI aprueba temporalmente el uso del esquema triple de clofarabina, etopósido y ciclofosfamida para el tratamiento de pacientes pediátricos con LLA y con recaídas o resistencia. Dado que la evidencia que respalda este uso del esquema triple de clofarabina, etopósido y ciclofosfamida es aún limitadam, se establece que el efecto del esquema triple se evaluará con los datos de los pacientes que hayan recibido el esquema por el lapso de un año para determinar el impacto de su uso en varios desenlaces clínicos. Esta información será tomada en cuenta en la reevaluación de este medicamento para efectos de un nuevo dictamen al terminar la vigencia del presente Dictamen Preliminar.

BCX4430 - A broad-spectrum antiviral adenosine nucleoside analog under development for the treatment of Ebola virus disease

The adenosine nucleoside analog BCX4430 is a direct-acting antiviral drug under investigation for the treatment of serious and life-threatening infections from highly pathogenic viruses, such as the Ebola virus. Cellular kinases phosphorylate BCX4430 to a triphosphate that mimics ATP; viral RNA polymerases incorporate the drug's monophosphate nucleotide into the growing RNA chain, causing premature chain termination. BCX4430 is active in vitro against many RNA viral pathogens, including the filoviruses and emerging infectious agents such as MERS-CoV and SARS-CoV. In vivo, BCX4430 is active after intramuscular, intraperitoneal, and oral administration in a variety of experimental infections. In nonclinical studies involving lethal infections with Ebola virus, Marburg virus, Rift Valley fever virus, and Yellow Fever virus, BCX4430 has demonstrated pronounced efficacy. In experiments conducted in several models, both a reduction in the viral load and an improvement in survival were found to be related to the dose of BCX4430. A Phase 1 clinical trial of intramuscular administration of BCX4430 in healthy subjects is currently ongoing

Purines and oxypurines in myocardial ischemia

To evaluate the plasma levels of purine nucleosides and oxypurines in the presence of other risk factors as additional markers for the diagnosis of myocardial ischemia and severity of myocardial infarction. A case control study was conducted on 101 patients with ischemic heart disease [stable angina, n=19: unstable angina, n=29: acute myocardial infarction [AMI]; n=53 patients] admitted to the Cardiology Unit at Al-Kadhimyia Teaching Hospital, Baghdad, Iraq from January to November 2007 in addition to 31 healthy controls. Blood samples were aspirated from those with AMI within the first 12 hours of onset of chest pain. Plasma adenosine [ADO], inosine [INO], hypoxanthine [HYP], and xanthine [XAN] were analyzed by high-performance liquid chromatography. The mean plasma ADO, INO, HYP, and XAN levels were raised in unstable angina over the control values. More increase in all nucleosides and oxypurines was reported in the plasma of patients with AMI as compared to the controls and those of stable angina. The INO [p = 0.01] and HYP [p = 0.001] values were increased significantly in diabetic men with AMI and at age of Conclusion: The levels of purines and their catabolites could be used as additional indices for prior or current ischemia. Pretreatment with such nucleosides, or their oxypurine derivatives, is suggested to improve the regional ventricular function after coronary artery occlusion

Chemical Constituents of the Fruiting Bodies of Clitocybe nebularis and Their Antifungal Activity

During a continuing search for antimicrobial substances from Korean native wild mushroom extracts, we found that the methanolic extract of the fruiting body of Clitocybe nebularis exhibited mild antifungal activity against pathogenic fungi. Therefore we evaluated the antifungal substances and other chemical components of the fruiting body of Clitocybe nebularis, which led to the isolation of nebularine, phenylacetic acid, purine, uridine, adenine, uracil, benzoic acid, and mannitol. Nebularine showed mild antifungal activity against Magnaphorthe grisea and Trichophyton mentagrophytes, and phenylacetic acid potently inhibited the growth of Pythium ultiumand displayed moderate antifungal activity against Magnaphorthe grisea, Botrytis cinerea, and Trichophyton mentagrophytes. The other isolated compounds showed no antimicrobial activity.

hTERT-targeted E. coli purine nucleoside phosphorylase gene/6-methylpurine deoxyribose therapy for pancreatic cancer / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pancreatic cancer is one of the most common tumors and has a 5-year survival for all stages of less than 5%. Most patients with pancreatic cancer are diagnosed at an advanced stage and therefore are not candidates for surgical resection. In recent years, investigation into alternative treatment strategies for this aggressive disease has led to advances in the field of gene therapy for pancreatic cancer. E. coli purine nucleoside phosphorylase/6-methylpurine deoxyribose (ePNP/MePdR) is a suicide gene/prodrug system where PNP enzyme cleaves nontoxic MePdR into cytotoxic membrane-permeable compounds 6-methylpurine (MeP) with high bystander activity. hTERT is expressed in cell lines and tissues for telomerase activity. In this study we examined the efficacy of ePNP under the control of hTERT promoter sequences and assessed the selective killing effects of the ePNP/prodrug MePdR system on pancreatic tumors.</p><p><b>METHODS</b>Recombinant pET-PNP was established. The protein of E. coli PNPase was expressed and an antibody to E. coli PNPase was prepared. Transcriptional activities of hTERT promoter sequences were analyzed using a luciferase reporter gene. A recombinant phTERT-ePNP vector was constructed. The ePNP/MePdR system affects SW1990 human pancreatic cancer cell lines in vitro.</p><p><b>RESULTS</b>The hTERT promoter had high transcriptional activity and conferred specificity on cancer cell lines. The antibody to E. coli PNPase was demonstrated to be specific for the ePNP protein. The MePdR treatment induced a high in vitro cytotoxicity on the sole hTERT-ePNP-producing cell lines and affected SW1990 cells in a dose-dependent manner.</p><p><b>CONCLUSIONS</b>The hTERT promoter control of the ePNP/MePdR system can provide a beneficial anti-tumor treatment in pancreatic cancer cell lines including a good bystander killing effect.</p>

Avaliação temporal da regulação do tônus vascular e da produção de superóxido induzido por purinas em aorta isolada de ratos Wistar endotoxêmicos / Analysis of purinergic modulation of vascular reactivity and superoxide production in aorta from endotoxemic rats

Pacientes sépticos podem evoluir para choque séptico, destes 40 por cento sobrevivem. Caracterizamos o modelo experimental, avaliamos fatores envolvidos na inflamação e avaliamos a modulação causada por purinas (ATP/ADP) na quantificação de superóxido (O2-) e na reatividade vascular da aorta isolada. Os resultados sugerem que na aorta isolada de animais endotoxêmicos, ATP e ADP aumentam a síntese de óxido nítrico (NO), porém somente o ATP reduz a biodisponibilidade de O2-, provavelmente pelo reacoplamento da NO sintase endotelial / Septic patients can evolve for septic shock and 40 per cent of these survive. We characterize the experimental model we evaluate involved factors in the inflammation and evaluate the modulation caused by purines (ATP/ADP) in the superoxide quantification (O2-) and in the vascular reactivity of isolated aorta. The results suggest that in isolated aorta of endotoxemics rats, ATP and ADP increase the endothelial nitric oxide synthase (NOS) however just ATP reduces the bio availability of O2-, probably for the re-couples of the endothelial NOS synthase...

In Vitro Perfusion Studies on Coronary Function of Cardiac Ischemia-Reperfusion in Spontaneously Hypertensive Rat Heart

BACKGROUND: Myocardial ischemia in human hypertension and in various animal models of hypertension may be due to abnormal maximal coronary vasodilator reserve and disturbaces of coronary vasomotion. The vascular reactivity defects in hypertension have been associated with the defective endothelium and sympathetic neural activation. However, such abnormalities in hypertension need to be elucidated. In the present study the effectsof cardiac ischemia reperfusion on coronary circulation, intramyocytic adenylates and purine nucleosides were examined in Langendorff-perfused Sprague Dawley rat (SD) and spontaneously hypertensive rat (SHR) hearts. Coronary venous and cardiac lactate and cardiac pyruvate were also measured. It should be noted that in the regulation of coronary flow the intrinsic flow autoregulation is highly variable due to coexisting metabolic flow control, and that natural coronary flow and cardiomyocytic energy state are normally reciprocally related in perfused heart. METHODS: For the Langendorff heart perfusion, bicarbonate perfusion buffer (pH 7.40+/-0.02,37degrees C) was equilibrated with 95% O2 : 5% CO2 and contained 5mM glucose (+5U/1 insulin) and 2mM pyruvate as energy-yielding substrates. Global hypoperfusion ischemia was induced by lowering coronary perfusion pressure of 100 to 40 cmH2O, followed by 20 min reperfusion. RESULTS: During the ischemia and reperfusion, metabolic acidosis and enhanced venous lactate output in SHR were observed with increases in coronary vascular resistance and myocardial oxygen consumption.In addition, coronary reactive hyperemia during reperfusion was depressed. Although ischemia-induced increase in combined adenosine plus inosine were abolished during prolonged reperfusion, SD still exhibited coronary vasodilation. The depressed reactive hyperemia in SHR was associated with decreases in cardiac adenosine triphosphate (ATP) pool and creatine phosphate/inorganic phosphate (CrP/Pi) ratio and an increase in cardiac lactate/pyruvate ratio. CONCLUSION: This abnormal vascular reactivity during ischemia and reperfusion in SHR may be in part due to an alteration in the cardiac energy state and hence to a mismatch between myocardial metabolic demand and supply.