Involvement of L-arginine-nitric oxide-cyclic guanosine monophosphate pathway in the antidepressant-like effect of venlafaxine in mice

The involvement of L-arginine-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling pathway in the antidepressant action of venlafaxine (dual serotonin and norepinephrine reuptake inhibitor) was investigated in mice. The antidepressant activity was assessed in forced swim test (FST) behavioral paradigm. Total immobility time was registered during the period of 6 min. Venlafaxine produced dose-dependent (4-16 mg/kg, i.p.) reduction in immobility period. The antidepressant-like effect of venlafaxine (8 mg/kg, i.p.) was prevented by pretreatment with l-arginine (750 mg/kg, i.p.) [substrate for nitric oxide synthase (NOS)]. Pretreatment of mice with 7-nitroindazole (7-NI) (25 mg/kg, i.p.) [a specific neuronal nitric oxide synthase (nNOS) inhibitor] produced potentiation of the action of subeffective dose of venlafaxine (2 mg/kg, i.p.). In addition, treatment of mice with methylene blue (10 mg/kg, i.p.) [direct inhibitor of both nitric oxide synthase (NOS) and soluble guanylate cyclase (sGC)] potentiated the effect of venlafaxine (2 mg/kg, i.p.) in the FST. Furthermore, the reduction in the immobility time elicited by venlafaxine (8 mg/kg, i.p.) was also inhibited by pretreatment with sildenafil (5 mg/kg, i.p.) [phosphodiesterase 5 inhibitor]. The various modulators used in the study did not produce any changes in locomotor activity per se. The results demonstrated that the antidepressant-like effect of venlafaxine in the FST involved an interaction with the L-arginine-NO-cGMP pathway.     

Differences in protein mobility between pioneer versus follower growth cones

Navigating growth cones need to integrate, process and respond to guidance signals, requiring dynamic information transfer within and between different compartments. Studies have shown that, faced with different navigation challenges, growth cones display dynamic changes in growth kinetics and morphologies. However, it remains unknown whether these are paralleled by differences in their internal molecular dynamics. To examine whether there are protein mobility differences during guidance, we developed multiphoton fluorescence recovery after photobleaching methods to determine molecular diffusion rates in pathfinding growth cones in vivo. Actively navigating growth cones (leaders) have consistently longer recovery times than growth cones that are fasciculated and less actively navigating (followers). Pharmacological perturbations of the cytoskeleton point to actin as the primary modulator of diffusion in differently behaving growth cones. This approach provides a powerful means to quantify mobility of specific proteins in neurons in vivo and reveals that diffusion is important during axon navigation.     

Simultaneous downregulation of CDK inhibitors p18(Ink4c) and p27(Kip1) is required for MEN2A-RET-mediated mitogenesis

Multiple endocrine neoplasia type 2A (MEN2A) is predisposed by mutations in the RET proto-oncogene. Low expression of the cyclin-dependent kinase inhibitor (CDKI) p27(Kip1) is present in thyroid tumors, and recent evidence demonstrates p27 downregulation by the active RET mutant, RET/PTC1, found in papillary thyroid carcinoma. This implicates decreased p27 activity as an important event during thyroid tumorigenesis. However, p27(-/-) mice develop MEN-like tumors only in combination with loss of another CDKI, p18(Ink4c). This suggests that p18 and p27 functionally collaborate in suppression of tumorigenesis, that loss of both is critical in the development of MEN tumors and that both p18 and p27 are regulated by RET. We report that induction of the constitutively active MEN2A-specific RET mutant, RET2A(C634R), correlates with reduced p18/p27, and elevated cyclin D protein levels, leading to increased CDK activity, increased pRb phosphorylation and proliferation under growth arrest conditions. Mechanistically, RET2A represses p18/p27 mRNA levels while elevating cyclin D1 mRNA levels. RET2A expression also correlates with decreased p27 protein stability. RET2A-mediated regulation of p18 and p27, but not of cyclins D1 and D2, requires functional mitogen-activated protein kinase signaling. Additionally, RET2A-dependent p18 repression is required and sufficient to increase cell proliferation. Perhaps most significantly, MEN2A adrenal tumors also display these changes in cell cycle expression profile, demonstrating the biological relevance of our cell culture studies. Our results demonstrate for the first time that RET2A regulates p18, and suggest that loss of not only p27 but also of p18 expression is a key step in MEN tumorigenesis.     

Anti-inflammatory effect of licofelone against various inflammatory challenges

We investigated the pharmacological profile of licofelone [6-(4-chlorophenyl)-2,3-dihydro-2,2-dimethyl-7-phenyl-1H-pyrrolizine-5-acetic acid] against different inflammogens. The anti-inflammatory and anti-hyperalgesic effect of licofelone (2, 30 and 100 mg/kg, p.o.) against all the challenges was statistically significant (P < 0.05) when compared with control and indomethacin (10 mg/kg, p.o.). The ED(50) value of 19.1 mg/kg (onset by 2 h, duration: short), 13.0 mg/kg and 16.8 mg/kg (onset by 1 h, duration: long) was observed for licofelone against carrageenan-, arachidonic acid- and bradykinin-induced paw oedema, respectively. Similarly, licofelone showed ED(50) value of 47.6 mg/kg (onset by 1 h, duration: long), 92.2 mg/kg (onset by 1 h, duration: medium), and 78.6 mg/kg (onset by 2 h, duration: medium) against carrageenan-, arachidonic acid- and bradykinin-induced mechanical hyperalgesia, respectively. The rank order of potency based on percent inhibition and percent reversal against inflammation and mechanical hyperalgesia, respectively, was found to be licofelone > indomethacin. Moreover, licofelone (10-100 mg/kg, p.o.) significantly (P < 0.05) and dose-dependently prevented the Freund's adjuvant-induced increased vascularity in mice (vascularity index; 10 mg/kg: 0.059 +/- 0.015; 20 mg/kg: 0.048 +/- 0.004; 30 mg/kg: 0.039 +/- 0.012; 100 mg/kg: 0.025 +/- 0.015 vs. control: 0.0285 +/- 0.003). Furthermore, the results suggested that dual inhibitors of cyclooxygenase and lipoxygenase like licofelone provide an effective control of inflammation and hyperalgesia against acute inflammation/hyperalgesia in rats and mice.     

Flow cytometric quantification of antigen D sites on red blood cells of partial D and weak D variants in India

The D antigenic sites are diminished in weak D and partial D variants. The aim of this study was to estimate D antigen on RBC in weak D and partial D variants in Indian population by using flow cytometric method. Blood samples of 42 cases of partial D, eight cases of weak D and 123 normal Rh phenotypes identified by serological methods were used in the study. An indirect immunofluorescence method was employed using 29 monoclonal anti-D as primary antibody. The D antigenic sites were calculated using control RBC as internal standard. The D antigenic sites in weak D and partial D variants are less than that found in normal Rh phenotypes. In weak D, the D antigenic sites were between 1500 and 7000 D antigens per cell. Among partial D variants, DVI had minimum and DVa had maximum number of D sites. Flow cytometry is a very good tool for demonstrating minor variation in D antigen when serological methods are inconclusive. The D antigenic sites per RBC in partial D variants identified in Indian population are reported for the first time.     

Plasmablastic lymphoma of the oral cavity in an HIV-positive patient: a case report and review of literature

Plasmablastic lymphoma (PBL) of the oral cavity is an uncommon, recently described B-cell derived lymphoma that is most commonly seen in patients with human immunodeficiency virus (HIV) infections. The authors report a rare case of PBL in the oral cavity of a 40-year-old man with HIV. The lymphoma cells were positive for leukocyte common antigen, CD79a, CD138, Epstein–Barr virus (EBV) and kappa light chain restriction and negative for CD20, CD3, S100, HMB45 and cytokeratins. The lesion regressed after treatment with local radiotherapy and systemic chemotherapy. The features of this rare disease are summarized based on a comprehensive review of the epidemiological, clinical and immunohistochemical findings of previously reported cases.     

HIV-1 Disease-Influencing Effects Associated with ZNRD1, HCP5 and HLA-C Alleles Are Attributable Mainly to Either HLA-A10 or HLA-B*57 Alleles

A recent genome-wide association study (GWAS) suggested that polymorphisms in or around the genes HCP5, HLA-C and ZNRD1 confer restriction against HIV-1 viral replication or disease progression. Here, we also find that these alleles are associated with different aspects of HIV disease, albeit mainly in European Americans. Additionally, we offer that because the GWAS cohort was a subset of HIV-positive individuals, selected based in part on having a low viral load, the observed associations for viral load are magnified compared with those we detect in a large well-characterized prospective natural history cohort of HIV-1-infected persons. We also find that because of linkage disequilibrium (LD) patterns, the dominant viral load- and disease-influencing associations for the ZNRD1 or HLA-C and HCP5 alleles are apparent mainly when these alleles are present in HLA-A10- or HLA-B*57-containing haplotypes, respectively. ZNRD1 alleles lacking HLA-A10 did not confer disease protection whereas ZNRD1-A10 haplotypes did. When examined in isolation, the HCP5-G allele associates with a slow disease course and lower viral loads. However, in multivariate models, after partitioning out the protective effects of B*57, the HCP5-G allele associates with disease-acceleration and enhanced viral replication; these associations for HCP5-G are otherwise obscured because of the very strong LD between this allele and a subset of protective B*57 alleles. Furthermore, HCP5 and HLA-C alleles stratify B*57-containing genotypes into those that associate with either striking disease retardation or progressive disease, providing one explanation for the long-standing conundrum of why some HLA-B*57-carrying individuals are long-term non-progressors, whereas others exhibit progressive disease. Collectively, these data generally underscore the strong dependence of genotype-phenotype relationships upon cohort design, phenotype selection, LD patterns and populations studied. They specifically demonstrate that the influence of ZNRD1 alleles on disease progression rates are attributable to HLA-A10, help clarify the relationship between the HCP5, HLA-C and HLA-B*57 alleles, and reaffirm a critical role of HLA-B*57 alleles in HIV disease. Furthermore, as the protective B*57-containing genotypes convey striking salutary effects independent of their strong impact on viral control, it is conceivable that T cell-based therapeutic vaccine strategies aimed at reducing viral loads may be inadequate for limiting AIDS progression, raising the potential need for complementary strategies that target viral load-independent determinants of pathogenesis.