An evolutionary analysis of trypanosomatid GP63 proteases

The trypanosomatid GP63 proteases are known to be involved in parasite–host interaction and exhibit strong sequence and structural similarities to those of their hosts and insect vectors. Based on genome sequences of the three trypanosomatids, Trypanosoma brucei, Trypanosoma cruzi, and Leishmania spp., we annotated all their GP63 proteases and divided highly duplicated T. cruzi GP63 proteases into four novel groups according to sequence features. In Leishmania spp., we studied the evolutionary dynamics of GP63 proteins and identified 57 amino acid sites that are under significant positive selections. These sites may contribute to the functional variations of the GP63 proteases and provide clues for vaccine development.     

Neuroendocrine and mucinous differentiation in signet ring cell carcinoma of the stomach: evidence for a common cell of origin in composite tumors

Composite tumors are rare neoplasms containing a mixture of 2 different cellular components present in roughly equal proportions. It is hypothesized that composite tumors arise from a multipotential stem cell with subsequent bidirectional differentiation. We present an unusual composite tumor of the stomach composed equally of signet ring cell carcinoma and low-grade neuroendocrine carcinoma. Twenty-one additional patients with signet ring cell carcinomas of the stomach were studied to determine the prevalence of neuroendocrine differentiation by morphology and immunohistochemistry for synaptophysin and chromogranin A. Immunohistochemistry for mucins 5AC and 2 was performed to assess for divergent differentiation toward foveolar and intestinal mucin phenotypes, respectively, and to evaluate for any potential relationship with neuroendocrine differentiation. We found morphologic evidence of neuroendocrine carcinoma in 4 (19%) of 21 consecutive signet ring carcinomas. E-cadherin immunostaining was subsequently performed on these 4 tumors plus the index case. All 5 tumors demonstrated concordance between the signet ring and neuroendocrine components. There was no distinct relationship to mucin 5AC/mucin 2 profiles, with the exception that all 11 intramucosal signet ring cell carcinomas from 4 patients with germ line cadherin 1 gene mutations were composed exclusively of mucin 5AC+ signet ring cells that lacked intestinal mucin and neuroendocrine differentiation. The concordant E-cadherin status in the neuroendocrine and signet ring cell tumor components and the frequent admixture of mucin 5AC+ cells with foveolar differentiation and mucin 2+ cells with intestinal differentiation may support the hypothesis that composite tumors arise from a common stem cell with bilineage or multilineage differentiation.     

Electrophysiological correlates of speech perception mechanisms and individual differences in second language attainment

In an increasingly globalized world mastering a second language (L2) provides a clear advantage. However, after early childhood, not everyone can easily learn a foreign language. The present study explored whether the large variability found in L2 attainment in the normal population, not diagnosed as learning disabled, is related to preattentive speech perception abilities. Using event‐related potentials (ERPs) we examined the mismatch negativity, P3a, and the late discriminative negativity (MMN‐P3a‐LDN) complex, which served as an index for preattentive foreign phonological contrast discrimination abilities. Our results show that, compared to unsuccessful L2 learners, successful L2 learners had shorter latencies of the MMN and P3a components and higher amplitudes of the LDN component. These results suggest that unsuccessful L2 learners have a deficient speech perception mechanism.     

Performance characteristics and comparison of Abbott and artus real-time systems for hepatitis B virus DNA quantification

Virological monitoring of hepatitis B virus (HBV) DNA is critical to the management of HBV infection. With several HBV DNA quantification assays available, it is important to use the most efficient testing system for virological monitoring. In this study, we evaluated the performance characteristics and comparability of three HBV DNA quantification systems: Abbott HBV real-time PCR (Abbott PCR), artus HBV real-time PCR with QIAamp DNA blood kit purification (artus-DB), and artus HBV real-time PCR with the QIAamp DSP virus kit purification (artus-DSP). The lower limits of detection of these systems were established against the WHO international standards for HBV DNA and were found to be 1.43, 82, and 9 IU/ml, respectively. The intra-assay and interassay coefficients of variation of plasma samples (1 to 6 log(10) IU/ml) ranged between 0.05 to 8.34% and 0.16 to 3.48% for the Abbott PCR, 1.53 to 26.85% and 0.50 to 12.89% for artus-DB, and 0.29 to 7.42% and 0.94 to 3.01% for artus-DSP, respectively. Ninety HBV clinical samples were used for comparison of assays, and paired quantitative results showed strong correlation by linear regression analysis (artus-DB with Abbott PCR, r = 0.95; Abbott PCR with artus-DSP, r = 0.97; and artus-DSP with artus-DB, r = 0.94). Bland-Altman analysis showed a good level of agreement for Abbott PCR and artus-DSP, with a mean difference of 0.10 log(10) IU/ml and limits of agreement of -0.91 to 1.11 log(10) IU/ml. No genotype-specific bias was seen in all three systems for HBV genotypes A, C, and D, which are predominant in this region. This finding illustrates that the Abbott real-time HBV and artus-DSP systems show more comparable performance than the artus-DB system, meeting the current guidelines for assays to be used in the management of hepatitis B.     

Implementation of a methicillin-resistant Staphylococcus aureus (MRSA) prevention bundle results in decreased MRSA surgical site infections

Background

Methicillin-resistant Staphylococcus aureus (MRSA) surgical site infections (SSIs) increase morbidity and mortality. We examined the impact of the MRSA bundle on SSIs.

Methods

Data regarding the implementation of the MRSA bundle from 2007 to 2008 were obtained, including admission and discharge MRSA screenings, overall MRSA infections, and cardiac and orthopedic SSIs. Chi-square was used for all comparisons.

Results

A significant decrease in MRSA transmission from a 5.8 to 3.0 per 1,000 bed-days (P < .05) was found after implementation of the MRSA bundle. Overall MRSA nosocomial infections decreased from 2.0 to 1.0 per 1,000 bed-days (P = .016). There was a statistically significant decrease in overall SSIs (P < .05), with a 65% decrease in orthopaedic MRSA SSIs and 1% decrease in cardiac MRSA SSIs.

Conclusion

Our data demonstrate that successful implementation of the MRSA bundle significantly decreases MRSA transmission between patients, the overall number of nosocomial MRSA infections, and MRSA SSIs.     

Novel SOX2 partner-factor domain mutation in a four-generation family

Anophthalmia (no eye), microphthalmia (small eye) and associated ocular developmental anomalies cause significant visual handicap. In most cases the underlying genetic cause is unknown, but mutations in some genes, such as SOX2, cause ocular developmental defects, particularly anophthalmia, in a subset of patients. Here, we describe a four-generation family with a p.Asp123Gly mutation in the highly conserved partner-factor interaction region of the SOX2 protein, which is important for cell-specific actions of SOX2. The proband in this family has bilateral anophthalmia and several other family members have milder ocular phenotypes, including typical optic fissure coloboma. Expression studies indicate that Sox2 is expressed in the eye at the site of closure of the optic fissure during development. The SOX2 mutation in this family implicates the partner-factor interaction region of SOX2 in contributing to the specificity of SOX2 action in optic fissure closure. Our findings indicate that investigation of SOX2 in a broad range of eye anomaly patients aids in the determination of particular functions of SOX2 in development.     

Rnf19a,a ubiquitin protein ligase,and Psmc3, a component of the 26S proteasome,Tether to the acrosome membranes and the head–tail coupling apparatus during rat spermatid development

We report the cDNA cloning of rat testis Rnf19a, a ubiquitin protein ligase, and show 98% and 93% protein sequence identity of testicular mouse and human Rnf19a, respectively. Rnf19a interacts with Psmc3, a protein component of the 19S regulatory cap of the 26S proteasome. During spermatid development, Rnf19a and Psmc3 are initially found in Golgi‐derived proacrosomal vesicles. Later on, Rnf19a, Psmc3, and ubiquitin are seen along the cytosolic side of the acrosomal membranes and the acroplaxome, a cytoskeletal plate linking the acrosome to the spermatid nuclear envelope. Rnf19a and Psmc3 accumulate at the acroplaxome marginal ring–manchette perinuclear ring region during spermatid head shaping and in the developing sperm head–tail coupling apparatus and tail. Rnf19a and Psmc3 may interact directly or indirectly with each other, presumably pointing to the participation of the ubiquitin–proteasome system in acrosome biogenesis, spermatid head shaping, and development of the head‐tail coupling apparatus and tail. Developmental Dynamics 238:1851–1861, 2009. © 2009 Wiley‐Liss, Inc.     

BAK1 gene variation and abdominal aortic aneurysms

We sought to examine the role of genetics in the multifactorial disease, abdominal aortic aneurysm (AAA), by studying sequence variation in the BAK1 gene (BAK1) that codes for an apoptotic‐promoting protein, as chronic apoptosis activation has been linked to AAA development and progression. BAK1 abdominal aorta cDNA from AAA patients and nondiseased individuals were compared with each other, as well as to the BAK1 genomic sequence obtained from matching blood samples. We found specific BAK1 single nucleotide polymorphism (SNP) containing alleles in both aneurysmic (31 cases) and healthy aortic tissue (5 cases) without seeing them in the matching blood samples. These same BAK1 SNPs have been reported, although rarely (average frequency <0.06%), in reference BAK1 DNA sequences. Based on this and other similar observations, we propose a novel hypothesis postulating that multiple variants of genes may preexist in “minority” forms within specific nondiseased tissues and be selected for, when intra‐ and/or extracellular conditions change. Therefore, the fact that different BAK1 variants can exist in both diseased and nondiseased AA tissues compared to matching blood samples, together with the rare occurrence of these same SNPs in reference sequences, suggests that selection may be a significant factor in AAA ontogeny. Hum Mutat 30:1–5, 2009. © 2009 Wiley‐Liss, Inc.