Nox2 Is a Mediator of Ischemia Reperfusion Injury

Delayed graft function (DGF) results from ischemia‐reperfusion injury (IRI) and the generation of reactive oxygen species. We hypothesized that NADPH oxidase 2 (Nox2) plays an important role in pathways leading to DGF. We tested this hypothesis in vitro, in an animal model of IRI using wild type and Nox2^?/? mice, and in patients with DGF. Under hypoxic conditions, primary tubular epithelial cells from Nox2^?/? mice had reduced expression of MMP2, vimentin, and HSP27. BUN and creatinine levels were significantly increased in both Nox2^?/? and WT mice at 4 weeks and 6 months after IRI, suggesting the development of acute and chronic kidney injury. At 4 weeks, kidney fibrosis (α‐SMA, picrosirius) and oxidative stress (dihydroethidine, HNE) were significantly reduced in Nox2^?/? mice, confirming the oxidative and pro‐fibrotic effects of Nox2. The molecular signature of IRI using genomic analyses demonstrated a significant decline in hypoxia reponse, oxidative stress, fibrosis, and inflammation in Nox2^?/? mice. Immunohistochemical analyses of pre‐implanatation kidney allograft biopsies from patients with subsequent DGF showed significantly greater Nox2 levels and vascular injury compared with patients without DGF. These studies demonstrate that Nox2 is a modulator of IRI and its absence is associated with reduced inflammation, OS, and fibrosis.

     

Preimplant Histologic Acute Tubular Necrosis and Allograft Outcomes

Background and objectives

The influence of deceased-donor AKI on post-transplant outcomes is poorly understood. The few published studies about deceased-donor preimplant biopsy have reported conflicting results regarding associations between AKI and recipient outcomes.

Design, setting, participants, & measurements

This multicenter study aimed to evaluate associations between deceased-donor biopsy reports of acute tubular necrosis (ATN) and delayed graft function (DGF), and secondarily for death-censored graft failure, first adjusting for the kidney donor risk index and then stratifying by donation after cardiac death (DCD) status.

Results

Between March 2010 and April 2012, 651 kidneys (369 donors, 4 organ procurement organizations) were biopsied and subsequently transplanted, with ATN reported in 110 (17%). There were 262 recipients (40%) who experienced DGF and 38 (6%) who experienced graft failure. DGF occurred in 45% of kidneys with reported ATN compared with 39% without ATN (P=0.31) resulting in a relative risk (RR) of 1.13 (95% confidence interval [95% CI], 0.9 to 1.43) and a kidney donor risk index–adjusted RR of 1.11 (95% CI, 0.88 to 1.41). There was no significant difference in graft failure for kidneys with versus without ATN (8% versus 5%). In stratified analyses, the adjusted RR for DGF with ATN was 0.97 (95% CI, 0.7 to 1.34) for non-DCD kidneys and 1.59 (95% CI, 1.23 to 2.06) for DCD kidneys (P=0.02 for the interaction between ATN and DCD on the development of DGF).

Conclusions

Despite a modest association with DGF for DCD kidneys, this study reveals no significant associations overall between preimplant biopsy-reported ATN and the outcomes of DGF or graft failure. The potential benefit of more rigorous ATN reporting is unclear, but these findings provide little evidence to suggest that current ATN reports are useful for predicting graft outcomes or deciding to accept or reject allograft offers.     

Randomized controlled trial of aripiprazole versus risperidone for the treatment of amphetamine-induced psychosis

Background: Lifetime prevalence of amphetamine-induced psychotic disorder is reported as being up to 23% for methamphetamine (MA) abusers. Approximately 25% of those with a baseline DSM-IV diagnosis of substance-induced psychosis are diagnosed with primary psychosis at one-year follow-up. Evidence on the treatment of amphetamine psychosis is very limited. Objectives: To investigate the efficacy of risperidone versus aripiprazole in treatment of amphetamine-induced psychotic symptoms. Methods: In a double-blind study, 45 participants were randomly allocated to either aripiprazole 15?mg or risperidone 4?mg daily over a six-week trial. Positive and negative symptoms of psychosis were assessed using the Scale for Assessment of Negative Symptoms (SANS) and the Scale for Assessment of Positive Symptoms (SAPS) at baseline and completion of the trial. Results: SANS and SAPS scores decreased significantly in both groups. Mean SAPS score reduction in risperidone and aripiprazole group was 16.20 and 10.80, respectively, after trial course (p?p?=?0.08). Conclusions: Both aripiprazole and risperidone were effective for patients diagnosed with amphetamine-induced psychotic disorder. However, risperidone had the greater effect on positive psychotic symptoms while patients with negative symptoms may respond better to aripiprazole. There is a case for further studies evaluating the efficacy of atypical antipsychotics in this disorder.     

Electron tomography on γ‐aminobutyric acid‐ergic synapses reveals a discontinuous postsynaptic network of filaments

The regulation of synaptic strength at γ‐aminobutyric acid (GABA)‐ergic synapses is dependent on the dynamic capture, retention, and modulation of GABA A‐type receptors by cytoplasmic proteins at GABAergic postsynaptic sites. How these proteins are oriented and organized in the postsynaptic cytoplasm is not yet established. To better understand these structures and gain further insight into the mechanisms by which they regulate receptor populations at postsynaptic sites, we utilized electron tomography to examine GABAergic synapses in dissociated rat hippocampal cultures. GABAergic synapses were identified and selected for tomography by using a set of criteria derived from the structure of immunogold‐labeled GABAergic synapses. Tomography revealed a complex postsynaptic network composed of filaments that extend ～100 nm into the cytoplasm from the postsynaptic membrane. The distribution of these postsynaptic filaments was strikingly similar to that of the immunogold label for gephyrin. Filaments were interconnected through uniform patterns of contact, forming complexes composed of 2–12 filaments each. Complexes did not link to form an integrated, continuous scaffold, suggesting that GABAergic postsynaptic specializations are less rigidly organized than glutamatergic postsynaptic densities. J. Comp. Neurol. 522:921–936, 2014. © 2013 Wiley Periodicals, Inc.     

Gender and ethnic differences in red cell distribution width and its association with mortality among low risk healthy United state adults

Limited information is available about gender and ethnic differences in red cell distribution width (RCDW) with regard to its relation to mortality in a population free of cardiovascular (CV) disease and diabetes. To assess gender and ethnic differences in RCDW and their effect on the association between RCDW and mortality, the Third National Health and Nutritional Examination Survey (n = 15,460, 1988 to 1994) data were examined. Multivariate adjusted Cox proportional hazard analysis was performed to assess effect of gender and ethnicity on the association between RCDW and mortality (total, CV disease, and coronary heart disease [CHD]). RCDW (mean ± SE) was greater in black women (13.1 ± 0.03) and men (13.4 ± 0.02) compared to women of white (12.9 ± 0.02) and other (13.0 ± 0.07) ethnicities and men of white (13.3 ± 0.02) and other (13.3 ± 0.07) ethnicities, respectively (p <0.001). The interaction between RCDW and gender was statistically significant for all study outcomes (p <0.001) but nonsignificant for RCDW and ethnicity. After adjusting for key variables, RCDW in women was associated with adjusted hazard ratios of 1.22 (95% confidence interval [CI] 1.14 to 1.31) for all-cause mortality, 1.17 (95% CI 1.07 to 1.28) for CV deaths, and 1.18 (95% CI 1.03 to 1.35) for CHD deaths; in men, adjusted hazard ratios were 1.29 (95% CI 1.20 to 1.38) for all-cause mortality, 1.27 (95% CI 1.17 to 1.37) for CV deaths, and 1.25 (95% CI 1.13 to 1.39) for CHD deaths (p <0.05 for all). In conclusion, blacks and men have significantly greater RCDWs compared to whites and women. Greater RCDW is associated with a greater risk of mortality in men compared to women, whereas no effect modification is observed by ethnicity.     

Using high throughput sequencing to explore the biodiversity in oral bacterial communities

High throughput sequencing of 16S ribosomal RNA gene amplicons is a cost-effective method for characterization of oral bacterial communities. However, before undertaking large-scale studies, it is necessary to understand the technique-associated limitations and intrinsic variability of the oral ecosystem. In this work we evaluated bias in species representation using an in vitro-assembled mock community of oral bacteria. We then characterized the bacterial communities in saliva and buccal mucosa of five healthy subjects to investigate the power of high throughput sequencing in revealing their diversity and biogeography patterns. Mock community analysis showed primer and DNA isolation biases and an overestimation of diversity that was reduced after eliminating singleton operational taxonomic units (OTUs). Sequencing of salivary and mucosal communities found a total of 455 OTUs (0.3% dissimilarity) with only 78 of these present in all subjects. We demonstrate that this variability was partly the result of incomplete richness coverage even at great sequencing depths, and so comparing communities by their structure was more effective than comparisons based solely on membership. With respect to oral biogeography, we found inter-subject variability in community structure was lower than site differences between salivary and mucosal communities within subjects. These differences were evident at very low sequencing depths and were mostly caused by the abundance of Streptococcus mitis and Gemella haemolysans in mucosa. In summary, we present an experimental and data analysis framework that will facilitate design and interpretation of pyrosequencing-based studies. Despite challenges associated with this technique, we demonstrate its power for evaluation of oral diversity and biogeography patterns.