Biochemical characterisation and novel classification of monofunctional S-adenosylmethionine decarboxylase of Plasmodium falciparum

Plasmodium falciparum like other organisms is dependent on polyamines for proliferation. Polyamine biosynthesis in these parasites is regulated by a unique bifunctional S-adenosylmethionine decarboxylase/ornithine decarboxylase (PfAdoMetDC/ODC). Only limited biochemical and structural information is available on the bifunctional enzyme due to the low levels and impurity of an instable recombinantly expressed protein from the native gene. Here we describe the high level expression of stable monofunctional PfAdoMetDC from a codon-harmonised construct, which permitted its biochemical characterisation indicating similar catalytic properties to AdoMetDCs of orthologous parasites. In the absence of structural data, far-UV CD showed that at least on secondary structure level, PfAdoMetDC corresponds well to that of the human protein. The kinetic properties of the monofunctional enzyme were also found to be different from that of PfAdoMetDC/ODC as mainly evidenced by an increased K(m). We deduced that complex formation of PfAdoMetDC and PfODC could enable coordinated modulation of the decarboxylase activities since there is a convergence of their k(cat) and lowering of their K(m). Such coordination results in the aligned production of decarboxylated AdoMet and putrescine for the subsequent synthesis of spermidine. Furthermore, based on the results obtained in this study we propose a new AdoMetDC subclass for plasmodial AdoMetDCs.     

Further psychometric analysis of the Florida Obsessive-Compulsive Inventory

This study examined the psychometric properties of the Florida Obsessive-Compulsive Inventory (FOCI [Storch, E. A., Stigge-Kaufman, D., Bagner, D., Merlo, L. J., Shapira, N. A., Geffken, G. R., et al. (2007). Florida Obsessive-Compulsive Scale: development, reliability, and validity. Journal of Clinical Psychology, 63, 851-859]). Participants were 89 adults with OCD presenting for treatment at a specialty clinic. A trained clinician administered the Yale-Brown Obsessive Compulsive Scale and patients completed the FOCI, Obsessive-Compulsive Inventory-Revised, Beck Depression Inventory-Second Edition, and State Trait Anxiety Inventory at baseline and following 14 weekly or daily cognitive behavioral therapy sessions. The internal consistency of FOCI Symptom Checklist and Severity Scale were good, and the concurrent and divergent validity of the FOCI Symptom Checklist and Severity Scale was supported through its associations with clinician-rated OCD symptom severity, and self-reported OCD, depressive, and anxiety measures. In addition, sensitivity to cognitive-behavioral treatment effects was shown as the Severity Scale scores were significantly lower following treatment compared to baseline. These findings not only replicate Storch et al. [Storch, E. A., Stigge-Kaufman, D., Bagner, D., Merlo, L. J., Shapira, N. A., Geffken, G. R., et al. (2007). Florida Obsessive-Compulsive Scale: development, reliability, and validity. Journal of Clinical Psychology, 63, 851-859] but also add unique construct validity data in support of the psychometrics of the FOCI.     

Neuroendocrine-immune interactions in rheumatoid arthritis: mechanisms of glucocorticoid resistance

Rheumatoid arthritis (RA) is characterized by chronic inflammation of the synovial membrane, leading to joint destruction. Many autoimmune diseases and disease states of chronic inflammation are accompanied by alterations in the complex interactions between the endocrine, nervous and immune systems. Glucocorticoids, an end product of the hypothalamic-pituitary-adrenal axis, are a mainstay treatment for many autoimmune diseases, including RA, because of their potent anti-inflammatory action. However, about 30% of patients with RA fail to respond to steroid therapy. There are various mechanisms that may contribute to the development of glucocorticoid resistance in inflammatory disorders, which will be the subject of this review. In addition, glucocorticoid resistance may be a contributing factor in the development of inflammatory/autoimmune diseases themselves. Therefore, further elucidation of these mechanisms will reveal new targets for therapeutic intervention in the treatment of RA.     

Expression and prognostic significance of prothymosin-alpha and ERp57 in human gastric cancer

PURPOSE: Prothymosin-alpha and ERp57 were previously identified as markers for gastric metaplasia in a mouse model of Helicobacter-induced gastric metaplasia and neoplasia. In this paper we assess whether the expression of these putative biomarkers in humans is correlated with gastric metaplasia and adenocarcinoma and clinical outcomes. METHODS: Eight tissue microarrays, containing 749 paraffin-embedded tissue cores from 164 gastric cancer patients, were stained for prothymosin-alpha and ERp57 by horseradish peroxidase immunohistochemical techniques. The proportion of stained cells per core was quantitated using the Ariol SL-50 automated image analysis system. RESULTS: Prothymosin-alpha stained a significantly higher percentage of nuclei in cancer and metastases compared with normal gastric mucosa. ERp57 staining was significantly decreased in cancer and metastases compared with both normal gastric mucosa and metaplasias. ERp57 expression also correlated with greater depth of tumor invasion and advanced stage of disease. Kaplan-Meier survival analysis determined that tumors with the highest quartile of ERp57 expression were statistically associated with longer postoperative survival. A Cox proportional hazard analysis showed that maintenance of ERp57 expression was associated with longer postoperative survival. CONCLUSIONS: These results suggest that although prothymosin-alpha is overexpressed in gastric adenocarcinoma, it is not associated with alterations in survival. In contrast, loss of ERp57 expression correlated with more aggressive disease and could provide useful prognostic information for gastric cancer patients.