Vav2 is an activator of Cdc42, Rac1, and RhoA

Vav and Vav2 are members of the Dbl family of proteins that act as guanine nucleotide exchange factors (GEFs) for Rho family proteins. Whereas Vav expression is restricted to cells of hematopoietic origin, Vav2 is widely expressed. Although Vav and Vav2 share highly related structural similarities and high sequence identity in their Dbl homology domains, it has been reported that they are active GEFs with distinct substrate specificities toward Rho family members. Whereas Vav displayed GEF activity for Rac1, Cdc42, RhoA, and RhoG, Vav2 was reported to exhibit GEF activity for RhoA, RhoB, and RhoG but not for Rac1 or Cdc42. Consistent with their distinct substrate targets, it was found that constitutively activated versions of Vav and Vav2 caused distinct transformed phenotypes when expressed in NIH 3T3 cells. In contrast to the previous findings, we found that Vav2 can act as a potent GEF for Cdc42, Rac1, and RhoA in vitro. Furthermore, we found that NH(2)-terminally truncated and activated Vav and Vav2 caused indistinguishable transforming actions in NIH 3T3 cells that required Cdc42, Rac1, and RhoA function. In addition, like Vav and Rac1, we found that Vav2 activated the Jun NH(2)-terminal kinase cascade and also caused the formation of lamellipodia and membrane ruffles in NIH 3T3 cells. Finally, Vav2-transformed NIH 3T3 cells showed up-regulated levels of Rac-GTP. We conclude that Vav2 and Vav share overlapping downstream targets and are activators of multiple Rho family proteins. Therefore, Vav2 may mediate the same cellular consequences in nonhematopoietic cells as Vav does in hematopoietic cells.

Potential misidentification of Burkholderia pseudomallei by API 20NE

Biochemical confirmation of the identity of Burkholderia pseudomallei in Singapore previously relied on the API 20NE panel of tests. After introducing an alternative proprietary biochemical panel, the Microbact 24E (MedVet, Adelaide, Australia), we noted that the API panel identified some presumptive B. pseudomallei isolates as other species. We therefore compared the performance of the API 20NE against the Microbact 24E with 50 distinct clinical isolates of B. pseudomallei, after 24 hours and after five days incubation of primary cultures. The API panel correctly identified 40 isolates. Four results were unacceptable or uninterpretable. Six isolates were misidentified as other species; the commonest being Chromobacterium violaceum. One of these was again identified as C. violaceum by the repeat API panel. Fourteen isolates, including the six misidentified isolates and four isolate pairs from separate sources in four separate patients, were typed using PCR amplification of repetitive extragenic palindromic sequences (REPS). The isolates identified as C. violaceum appeared to have identical REPS patterns, suggesting that some of the errant API results may be due to a single locally prevalent strain of B. pseudomallei. A previous suggestion that C. violaceum may produce a melioidosis-like illness may therefore be due to laboratory misidentification of B. pseudomallei with the API 20NE biochemical test panel.

Protein sequence entropy is closely related to packing density and hydrophobicity

We investigated the correlation between the Shannon information entropy, 'sequence entropy', with respect to the local flexibility of native globular proteins as described by inverse packing density. These are determined at each residue position for a total set of 130 query proteins, where sequence entropies are calculated from each set of aligned residues. For the accompanying aggregate set of 130 alignments, a strong linear correlation is observed between the calculated sequence entropy and the corresponding inverse packing density determined at an associated residue position. This region of linearity spans the range of C(alpha) packing densities from 12 to 25 amino acids within a sphere of 9 angstrom radius. Three different hydrophobicity scales all mimic the behavior of the sequence entropies. This confirms the idea that the ability to accommodate mutations is strongly dependent on the available space and on the propensity for each amino acid type to be buried. Future applications of these types of methods may prove useful in identifying both core and flexible residues within a protein.

DOES THE ENDOSCOPIC TECHNIQUE OF URETEROCELE INCISION MATTER?

PURPOSE

Endoscopic ureterocele decompression is a well established procedure in children. However, an accurate endoscopic incision may be challenging in large ectopic ureteroceles. We describe a percutaneously assisted technique to facilitate the ease of ureterocele incision and review other described methods.

MATERIALS AND METHODS

We reviewed the medical records of 12 children with ectopic ureteroceles subtending a double collecting system who underwent endoscopic, percutaneously assisted incision. Six ureteroceles were on the left side, 5 were on the right side and 1 child had bilateral ureteroceles. Decompression results were evaluated by ultrasound and Tc-mercaptoacetyltriglycine imaging during a mean of 2.8 years of followup.

RESULTS

There were 7 girls and 5 boys. Mean age at presentation was 11.6 months (range 1 week to 6 years). The decompression success rate was 84% (11 of 13 renal units), and improved renal function and drainage was noted in 5 of 12 patients (41.6%). Seven of 12 patients had vesicoureteral reflux, of whom 2 were asymptomatic at followup and, hence, were treated conservatively. Five children underwent surgery because of recurrent urinary tract infections.

CONCLUSIONS

Although our results are similar to those of other methods, percutaneously assisted cystoscopic incision of ureterocele enables easier and more accurate decompression. However, when comparing the various techniques described, it seems that postoperative results mostly reflect the anatomical and functional characteristics of the urinary system rather than the technique used.

Management of post-operative bladder spasm

OBJECTIVE

Pain management following bladder surgery in children is often complicated by bladder spasm. The overall severity of spasm can be reduced with opioids, anticholinergic medication and sedatives, although breakthrough spasms often occur. At the Royal Children's Hospital, Melbourne, intravesical bupivacaine has been used to manage postoperative bladder spasm to good effect. The administration of intravesical bupivacaine is analysed in this prospective audit of locally applied intravesical anaesthetic and compared with other methods.

METHOD

From February to August 2003, histories of 58 patients who had intravesical bupivacaine were studied and compared with six other methods of management of postoperative bladder spasm.

CONCLUSION

Data showed that epidural anaesthesia was the most effective treatment of pain, with a pain score reduction of 6.6, compared with a reduction of 6.1 with intravesical bupivacaine, and 4.5 using intravenous morphine. However, intravesical bupivacaine was the most effective method for the relief of bladder spasm.

Prediction of stone disease by discriminant analysis and artificial neural networks in genetic polymorphisms: a new method

OBJECTIVE

To use information from genetic polymorphisms and from patients (drinking/exercise habits) to identify their association with stone disease, the main analytical and predictive tools being discriminant analysis (DA) and artificial neural networks (ANNs).

PATIENTS, SUBJECTS AND METHODS

Urinary stone disease is common in Taiwan; the formation of calcium oxalate stone is reportedly associated with genetic polymorphisms but there are many of these. Genotyping requires many individuals and markers because of the complexity of gene-gene and gene-environmental factor interactions. With the development of artificial intelligence, data-mining tools like ANNs can be used to derive more from patient data in predicting disease. Thus we compared 151 patients with calcium oxalate stones and 105 healthy controls for the presence of four genetic polymorphisms; cytochrome p450c17, E-cadherin, urokinase and vascular endothelial growth factor (VEGF). Information about environmental factors, e.g. water, milk and coffee consumption, and outdoor activities, was also collected. Stepwise DA and ANNs were used as classification methods to obtain an effective discriminant model.

RESULTS

With only the genetic variables, DA successfully classified 64% of the participants, but when all related factors (gene and environmental factors) were considered simultaneously, stepwise DA was successful in classifying 74%. The results for DA were best when six variables (sex, VEGF, stone number, coffee, milk, outdoor activities), found by iterative selection, were used. The ANN successfully classified 89% of participants and was better than DA when considering all factors in the model. A sensitivity analysis of the input parameters for ANN was conducted after the ANN program was trained; the most important inputs affecting stone disease were genetic (VEGF), while the second and third were water and milk consumption.

CONCLUSIONS

While data-mining tools such as DA and ANN both provide accurate results for assessing genetic markers of calcium stone disease, the ANN provides a better prediction than the DA, especially when considering all (genetic and environmental) related factors simultaneously. This model provides a new way to study stone disease in combination with genetic polymorphisms and environmental factors.

Guide wire-assisted urethral dilatation for urethral strictures in pediatric urology

PURPOSE

The aim of this study was to report the results of 32 cases of dilatation of urethral stricture using a guide wire and sheath dilator technique supplemented by clean intermittent catheterization if further stabilization of the urethral stricture was felt warranted.

METHODS

The procedure involves insertion of a straight flexi-tip lubricated guide wire through the urethral stricture under cystoscopic guidance followed by insertion of a series of sheath dilators. Dilatation was followed by insertion of a Foley catheter, which was left in situ for 1 to 3 days. Patients underwent repeat cystoscopy to evaluate the urethra for recurrent stricture and those with a recalcitrant stricture were commenced on clean intermittent catheterization (CIC) to stabilize the narrowing.

RESULTS

Thirty-two patients were included. They have been followed up for up to 2(1/2) years after their last cystoscopy (mean, 16 months). Thirteen of 32 patients had more than 4 dilatations under anesthesia. Twelve patients had undergone CIC postoperatively. Complications included a urinary tract infection in 3 boys and bladder spasms in one. No false passage or sepsis occurred with this approach.

CONCLUSIONS

Guide wire-assisted urethral dilatation helps avoid risks associated with blind dilatation techniques and appears to be a safe and simple alternative for management of urethral strictures in pediatric urology.

Missed diagnosis of influenza B virus due to nucleoprotein sequence mutations, Singapore, April 2011

A new influenza B variant was discovered in Singapore in April 2011 during diagnostic testing of a 3-year-old boy with respiratory symptoms. Influenza B virus was isolated from culture and confirmed by standard immunofluorescence testing, but was not detected by the routine, in-house influenza screening reverse-transcription polymerase chain reaction assay that targets the nucleoprotein (NP) gene. Subsequent sequencing investigations demonstrated that several other published assays targeting NP could also fail to detect this novel variant.

Ulaanbaatar Procedure for Tubularization of the Glans in Severe Hypospadias

PURPOSE

We developed a new procedure for the repair of proximal hypospadias in which the distal urethra is constructed as part of the first of 2 stages, and reviewed the results of 34 cases.

MATERIALS AND METHODS

We performed stage 1 of the Ulaanbaatar procedure in 35 children 0.6 to 11 years old (average age 2.5), and stage 2 in 20. The meatus was at the posterior third of the shaft in 14 children, at the penoscrotal junction in 16 and in the perineum in 5. Three patients had a previous operation, and none had Byars flaps formed. Followup was less than 2(1/2) years for stage 1 and less than 1(1/2) years for stage 2. In 2 stage 2 procedures a free graft was also used to augment the proximal part of the urethroplasty.

RESULTS

Urethral fistula did not develop in any patient, a minor early stricture occurred in 2 patients and 1 urethral diverticulum occurred in 1 patient after stage 2. In all patients the glans and meatus were more normal compared to other 2-stage procedures after the first operation, and the cosmetic result was usually satisfactory.

CONCLUSIONS

The Ulaanbaatar technique provides an alternative approach to the formation of the glans urethra in severe hypospadias. It does not have the risks associated with a single stage procedure but has the benefit of enabling tunneling of the urethra through the glans, thus facilitating a favorable cosmetic outcome and an easy stage 2.

Genome-wide association study identifies 18 new susceptibility variants loci associated with Brugada Syndrome

 

The Brugada Syndrome (BrS) is characterized by ST-segment elevation in the right precordial leads and is associated with an increased risk of sudden cardiac death. The disorder was initially described as a monogenic primary cardiac electrical disease. However, mutations in SCN5A, encoding the cardiac sodium channel (NaV1.5), which is the major gene associated with the disorder are found in only around 20% of cases and are associated with low penetrance. Furthermore many cases did not display familial aggregation. Based on a previous GWAS conducted on 312 BrS patients and the discovery of the unexpected strong effect of 3 common variants, we proposed that the BrS may comprise a more complex inheritance model. We conducted a genome-wide association study on 2820 individuals with BrS and 10001 ancestry-matched controls to uncover additional genetic loci that modulate susceptibility to BrS, to characterize further the BrS genetic architecture and to uncover new molecular mechanisms.

We identified 21 susceptibility variants that passed the genome-wide statistical significance threshold (P<5.10–8), of which 18 were novel. Eight were located at the SCN5A-SCN10A locus, illustrating the central role of NaV1.5 in the disease. Interestingly, 9 occur in the vicinity of genes known to play a crucial role in cardiac development (HEY2, TBX20, GATA4, ZFPM2, WT1, TBX5, IRX3, IRX5) and / or control cardiac ion channel expression. Of note, 2 others signals occurred in the vicinity of microtubule / cytoskeleton associated proteins (MAPRE2 and MYO18B). Through studies in zebrafish and in human iPSC-derived cardiomyocytes, we demonstrate a role of MAPRE2 on NaV1.5 function.

We identified 18 new susceptibility variants associated with BrS and uncovered a new pathophysiological molecular mechanism underlying BrS susceptibility. We provided further support for a complex genetic architecture underlying susceptibility for the disorder.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): H2020 - Marie Sklodowska Curie IF grant, Rising star grant from the Pays de la Loire regional council

Missed diagnosis of influenza B virus due to nucleoprotein sequence mutations, Singapore, April 2011

A new influenza B variant was discovered in Singapore in April 2011 during diagnostic testing of a 3-year-old boy with respiratory symptoms. Influenza B virus was isolated from culture and confirmed by standard immunofluorescence testing, but was not detected by the routine, in-house influenza screening reverse-transcription polymerase chain reaction assay that targets the nucleoprotein (NP) gene. Subsequent sequencing investigations demonstrated that several other published assays targeting NP could also fail to detect this novel variant.

The role of P2Y12 in cardiovascular disease beyond atherothrombosis: P2Y12 signaling promotes emergency hematopoiesis after myocardial infarction

Background

Adenosine diphosphate (ADP) plays a pivotal role in platelet activation. The purinergic ADP-receptor P2Y12 has therefore been targeted in the treatment of cardiovascular disease (CVD) to prevent atherothrombosis (1). Beyond P2Y12 expression on platelets, purinergic receptors have also been described on hematopoietic stem and progenitor cells (LSK) (2). After myocardial infarction (MI), accelerated LSK proliferation launches emergency hematopoiesis as the driving force behind the inflammatory response to MI, increasing inflammatory cell production in the bone marrow (BM) and providing leukocyte resupply for local cell recruitment to the infarct (3). The inflammatory cascade after MI covers intricate multilayered interactions between the injured myocardium and the hematopoietic BM that still remain to be fully elucidated and may unearth novel therapeutic strategies. Whereas P2X receptors have recently been found to be involved in cell trafficking (4), the role of P2Y receptors in the hematopoietic BM have not yet been characterized.

Purpose

This study aims to characterize the influence of P2Y12 signaling on emergency hematopoiesis and cardiac remodeling after MI.

Methods

Permanent coronary ligation was performed for MI to assess BM activation, inflammatory cell composition, cardiac remodeling and function in murine global and platelet-specific P2Y12 knockout models and under pharmacological P2Y12 inhibition with prasugrel using flow cytometry, qPCR, immunohistochemistry and echocardiography. In vitro studies including colony forming unit (CFU) assays and flow cytometry allowed for investigation of ADP-dependent effects on LSK cells and intracellular pathway analysis.

Results

We identified ADP as a danger signal for the hematopoietic BM, fueling emergency hematopoiesis by promoting Akt phosphorylation and cell cycle progression. Detection of P2Y12 expression in LSK implicated a direct effect of ADP on LSK via P2Y12 signaling. P2Y12 deficiency and P2Y12 inhibition with prasugrel decelerated emergency hematopoiesis and consecutively reduced the excessive inflammatory response to MI, translating to lower numbers of hematopoietic progenitors and inflammatory cells in the blood and infarct. Ultimately, P2Y12 inhibition ameliorated chronic adverse cardiac remodeling and preserved cardiac function after MI.

Conclusion

ADP-dependent P2Y12-mediated activation of hematopoietic stem and progenitor cells in the BM promotes emergency hematopoiesis after MI and fuels post-ischemic inflammation, proposing a novel role of P2Y12 antagonists in CVD beyond atherothrombosis.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft (DFG)

Reaching NLM through the Internet

Currently, many of the electronic services are still new, and there may be a need for further fine-tuning and changes. Having separate electronic addresses for each service rather than having one centralized address will make it easier for NLM to identify and isolate questions or problems. The Appendix summarizes the commands and addresses mentioned in this article.