Heme oxygenase-2 is activated by calcium-calmodulin

The heme oxygenase family of enzymes catalyzes the metabolism of heme to biliverdin, ferrous iron, and carbon monoxide (CO). At least two isoforms exist, heme oxygenase-1 (HO1) and heme oxygenase-2 (HO2), which are encoded by separate genes. HO2 is selectively enriched in neurons, and substantial evidence suggests that HO2-derived CO functions as a neurotransmitter/neuromodulator. However, a molecular mechanism for the rapid activation of HO2 during neuronal activity has not been described. Through a yeast two-hybrid screen we identified calmodulin as a potential regulator of HO2 activity. Calmodulin binds with nanomolar affinity to HO2 in a calcium-dependent manner via a canonical 1-10 motif, resulting in a 3-fold increase in catalytic activity. Mutations within this motif block calmodulin binding and calcium-dependent stimulation of enzyme activity in vitro and in intact cells. The calcium mobilizing agents ionomycin and glutamate stimulate endogenous HO2 activity in primary cortical cultures, establishing in vivo relevance. Calcium-calmodulin provides a mechanism for rapid and transient activation of HO2 during neuronal activity.     

Complicated Role of Exercise in Modulating Memory: A Discussion of the Mechanisms Involved

Neurochemical Research - Evidence has shown the beneficial effects of exercise on learning and memory. However, many studies have reported controversial results, indicating that exercise can impair...     

Molecular confirmation of the occurrence of Elysia cf. tomentosa (Mollusca: Heterobranchia) in the Persian Gulf

The molluscan fauna of the Persian Gulf has recently been relatively well documented, yet there are few records of heterobranch sea slugs (opisthobranchs) from the Arabian parts and no report from the Iranian waters. Here we report for the first time the occurrence of one of these molluscs in the northern Persian Gulf (Bandar Abbas, Iran). Sacoglossan specimens were collected in association with the seaweed, Caulerpa sertularioides. Since morphological attributes were not adequately reliable for species identification, molecular approaches were carried out. Maximum-likelihood and Bayesian Inference analysis of partial DNA sequences of the mitochondrial cytochrome c oxidase subunit I (COI) locus were used for DNA barcoding of large-bodied specimens of Elysia. All Persian Gulf specimens were genetically confirmed as Elysia cf. tomentosa sp. 5, one of at least five morphologically similar but genetically distinct species in the taxonomically challenging and unresolved E. tomentosa complex. This species has previously been recorded only from Australia and Thailand and our finding adds another distant point to the geographic distribution of this species.     

Comparison of Plasticizer Effect on Thermo-responsive Properties of Eudragit RS Films

Preparation of an intelligent drug delivery system which releases the drug in response to the environmental stimuli in a controlled manner is one of the interesting subjects and it is the purpose of this study. Films composed of Eudragit RS and different percentages of plasticizers (0%, 5%, 10%, or 20% w/w based on polymer weight), poly ethylene glycol 400 or triethyl citrate (TEC), were prepared by solvent casting method. Glass transition temperatures of the films were determined by differential scanning colorimetery. Water uptake and drug permeation through membranes with the glass transition temperature (Tg) close to the body temperature were investigated. Propranolol hydrochloride and acetaminophen were used as model drugs in permeation studies. The results showed that Eudragit RS films with 20% of either plasticizer showed thermo-responsivity around body temperature. The water uptake of the films and the permeation rates of both drugs increased at temperatures above the Tg of the films. The films containing TEC was found to be more appropriate thermo-responsive membrane due to a higher sensitivity to temperature and more ability to control drug release.     

A simple and rapid HPLC method for quantitation of interferon-alpha2b in dosage forms and delivery systems

Development of reliable assay methods for quantitation of interferons in dosage forms has encountered serious limitations because of the physicochemical nature of these proteins as well as the sensitivity/selectivity issues. A rapid, available, and easy-to-use reversed-phase HPLC method has been developed for quantitative analysis of interferon-alpha2b in pharmaceuticals. The reversed- phase method was based on a gradient system using a wide-pore C4 column and produced linear response in drug concentration range of 0.25-5 MIU (r = 0.9997). The average within-run and between-run variables of the method were 4.19 and 9.40%, respectively, with corresponding average accuracies of 99.48+/-4.11 and 102.83+/-9.51%. The limits of detection (LOD) and quantitation (LOQ) of the method were 0.125 and 0.25MIU/ml, respectively. The practical applicability of the method was proven throughout a post-marketing quality control program on interferon-alpha2b products (PD-feron) produced and marketed in Iran.