Association study of the vesicular monoamine transporter gene SLC18A2 with tardive dyskinesia

Tardive dyskinesia (TD) is an involuntary movement disorder that can occur in up to 25% of patients receiving long-term first-generation antipsychotic treatment. Its etiology is unclear, but family studies suggest that genetic factors play an important role in contributing to risk for TD. The vesicular monoamine transporter 2 (VMAT2) is an interesting candidate for genetic studies of TD because it regulates the release of neurotransmitters implicated in TD, including dopamine, serotonin, and GABA. VMAT2 is also a target of tetrabenazine, a drug used in the treatment of hyperkinetic movement disorders, including TD. We examined nine single-nucleotide polymorphisms (SNPs) in the SLC18A2 gene that encodes VMAT2 for association with TD in our sample of chronic schizophrenia patients (n = 217). We found a number of SNPs to be nominally associated with TD occurrence and the Abnormal Involuntary Movement Scale (AIMS), including the rs2015586 marker which was previously found associated with TD in the CATIE sample ( Tsai et al., 2010), as well as the rs363224 marker, with the low-expression AA genotype appearing to be protective against TD (p = 0.005). We further found the rs363224 marker to interact with the putative functional D2 receptor rs6277 (C957T) polymorphism (p = 0.001), supporting the dopamine hypothesis of TD. Pending further replication, VMAT2 may be considered a therapeutic target for the treatment and/or prevention of TD.     

N-Acetylaspartate in the CNS: from neurodiagnostics to neurobiology

The brain is unique among organs in many respects, including its mechanisms of lipid synthesis and energy production. The nervous system-specific metabolite N-acetylaspartate (NAA), which is synthesized from aspartate and acetyl-coenzyme A in neurons, appears to be a key link in these distinct biochemical features of CNS metabolism. During early postnatal central nervous system (CNS) development, the expression of lipogenic enzymes in oligodendrocytes, including the NAA-degrading enzyme aspartoacylase (ASPA), is increased along with increased NAA production in neurons. NAA is transported from neurons to the cytoplasm of oligodendrocytes, where ASPA cleaves the acetate moiety for use in fatty acid and steroid synthesis. The fatty acids and steroids produced then go on to be used as building blocks for myelin lipid synthesis. Mutations in the gene for ASPA result in the fatal leukodystrophy Canavan disease, for which there is currently no effective treatment. Once postnatal myelination is completed, NAA may continue to be involved in myelin lipid turnover in adults, but it also appears to adopt other roles, including a bioenergetic role in neuronal mitochondria. NAA and ATP metabolism appear to be linked indirectly, whereby acetylation of aspartate may facilitate its removal from neuronal mitochondria, thus favoring conversion of glutamate to alpha ketoglutarate which can enter the tricarboxylic acid cycle for energy production. In its role as a mechanism for enhancing mitochondrial energy production from glutamate, NAA is in a key position to act as a magnetic resonance spectroscopy marker for neuronal health, viability and number. Evidence suggests that NAA is a direct precursor for the enzymatic synthesis of the neuron specific dipeptide N-acetylaspartylglutamate, the most concentrated neuropeptide in the human brain. Other proposed roles for NAA include neuronal osmoregulation and axon-glial signaling. We propose that NAA may also be involved in brain nitrogen balance. Further research will be required to more fully understand the biochemical functions served by NAA in CNS development and activity, and additional functions are likely to be discovered.     

IgM nephropathy in adults: incidence and correlation with electron microscopic features

IgM nephropathy is characterised on light microscopy (LM) by variable features of normal glomeruli to mesangial hypercellularity; and immunofluorescence (IF) deposits of LgM. Our aim was to study the incidence of IgM nephropathy in adults with primary glomerular disease, with correlation to electron microscopy (EM) features. All adults presenting with proteinuria glomerular hematuria underwent renal biopsy. We excluded patients with systemic diseases and post-infectious glomerulonephritis. All the specimens were evaluated by LM, IF and EM. Our series had 146 cases. Of the 42 cases diagnosed on LM as minimal change disease, mesangial deposition of IgM was present in 11 cases. In addition there were seven cases of mesangioproliferative glomerulonephritis with mesangial IgM deposition. Thus, there were a total of 18 cases of IgM nephropathy (12.3%). Only six of these 18 cases showed typical electron dense deposits in the mesangium on EM. We feel that IgM nephropathy is probably a separate pathological entity, comprising 12.3% of all adults with primary chronic glomerulopathy. Electron dense deposits are seen in only about a third of these cases.     

Simvastatin does not exhibit therapeutic anti-inflammatory effects in asthma

BACKGROUND: Statins lower cholesterol and also exhibit anti-inflammatory properties. In vitro and animal studies have suggested they may be useful for the treatment of a number of inflammatory conditions. OBJECTIVE: To evaluate the in vivo therapeutic potential of simvastatin as an anti-inflammatory agent in patients with asthma. METHODS: Potential signal from treatment effect was optimized by withdrawing all anti-inflammatory treatment for the duration of the study. Participants received 1 month of daily simvastatin and 1 month of daily placebo in a randomized, double-blind crossover trial. A total of 16 patients completed per protocol. Asthmatic inflammation was evaluated by measuring exhaled tidal nitric oxide, alveolar nitric oxide, sputum and peripheral eosinophil count, methacholine hyperresponsiveness, salivary eosinophilic cationic protein, and C-reactive protein. Measurements of dynamic and static lung volumes and of cholesterol were also made. RESULTS: After initial withdrawal of usual asthma medication, there was a 1.43 geometric mean fold increase (ie, 43% difference) in fraction of exhaled nitric oxide (95% CI, 1.15 to 1.78; P = .004). Compared with placebo, simvastatin led to a 0.86 geometric mean fold decrease (95% CI, 0.7 to 1.04; P = .15) in exhaled nitric oxide (ie, a 14% difference), and a -0.18 doubling dilution shift (95% CI, -1.90 to 1.55; P = 1.0) in methacholine hyperresponsiveness. There were no significant differences in other inflammatory outcomes, lung volumes, or airway resistance between simvastatin and placebo. Treatment with simvastatin led to a significant reduction (P < .005) of total and low-density lipoprotein cholesterol. CONCLUSION: There is no evidence to suggest simvastatin has anti-inflammatory activity in patients with asthma. CLINICAL IMPLICATIONS: Simvastatin is not useful for the treatment of asthma.     

N-hydroxy-pyrroline modification of verapamil exhibits antioxidant protection of the heart against ischemia/reperfusion-induced cardiac dysfunction without compromising its calcium antagonistic activity

Any clinical intervention (e.g., coronary angioplasty, thrombolysis) used to reintroduce blood flow to an ischemic region of the myocardium is accompanied by a complex enzymatic cascade of reactions resulting in severe injury to the heart, termed myocardial ischemia/reperfusion (I/R) injury. In this study, we evaluated the ability of H-3010 (1-hydroxy-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrole-3-carboxylic acid (2-(3,4-dimethoxyphenyl)-5-([2-(3,4-dimethoxyphenyl)ethyl]-methylamino)-2-isopropylpentyl)-amide), a pyrroline modification of verapamil (2-(3,4-dimethoxyphenyl)-5-[2-(3,4-dimethoxyphenyl)ethylmethyl-amino]-2-(1-methylethyl)pentanenitrile), to protect the heart against I/R-mediated injury. Isolated perfused rat hearts pretreated with verapamil and H-3010 were subjected to 30 min of global no-flow ischemia followed by 45 min of reperfusion. The recovery (expressed as a percentage of preischemic baseline) in contractile function (left ventricular developed pressure) of hearts subjected to I/R was significantly higher in hearts treated with H-3010 at 5 microM (51.0 +/- 6.4%) as well as at 50 microM (75.1 +/- 7.4%) as compared with verapamil at 5 microM (32.2 +/- 3.7%) or untreated control hearts (18.1 +/- 2.8%). Creatine kinase release was significantly attenuated in hearts treated with H-3010 (45.7 +/- 4.5 U/liter) as compared with untreated controls (131.5 +/- 6.4 U/liter). Similar trends were also observed for lactate dehydrogenase release as well. A marked reduction in percent area of infarction was observed in the H-3010 group (11.7 +/- 1.6%) compared with verapamil (25.1 +/- 2.9%) and control (41.3 +/- 1.9%) groups. Additional in vitro studies showed a marked decrease in reactive oxygen species generation with H-3010. In conclusion, our data clearly demonstrated that the verapamil derivative, H-3010, significantly decreased I/R-induced cardiac dysfunction. This can be attributed to the combined benefits of the pyrroline moiety (antioxidant) and the parent verapamil component (antiarrhythmic) in the protection of the heart from I/R-induced injury.