Immunohistochemical localization of phosphohistidine phosphatase PHPT1 in mouse and human tissues

Protein histidine phosphorylation accounts for about 6% of the total protein phosphorylation in eukaryotic cells; still details concerning histidine phosphorylation and dephosphorylation are limited. A mammalian 14-kDa phosphohistidine phosphatase, also denominated PHPT1, was found 6 years ago that provided a new tool in the study of phosphohistidine phosphorylation. The localization of PHPT1 mRNA by Northern blot analysis revealed high expression in heart and skeletal muscle. The main object of the present study was to determine the PHPT1 expression on protein level in mouse tissues in order to get further information on the physiological role of the enzyme. Tissue samples from adult mice and 14.5-day-old mouse embryos were processed for immunostaining using a PHPT1-specific polyclonal antibody. The same antibody was also provided to the Swedish human protein atlas project (HPR) (http://www.proteinatlas.org/index.php). The results from both studies were essentially consistent with the previously reported expression of mRNA of a few human tissues. In addition, several other tissues, including testis, displayed a high protein expression. A salient result of the present investigation was the ubiquitous expression of the PHPT1 protein and its high expression in continuously dividing epithelial cells

Ethics takes time, but not that long

© 2007 Hansson et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Reappraisal of Metformin Efficacy in the Treatment of Type 2 Diabetes: A Meta-Analysis of Randomised Controlled Trials

Catherine Cornu and colleagues performed a meta-analysis of randomised controlled trials of metformin efficacy on cardiovascular morbidity or mortality in patients with type 2 diabetes and showed that although metformin is considered the gold standard, its benefit/risk ratio remains uncertain

High-Capacity Conductive Nanocellulose Paper Sheets for Electrochemically Controlled Extraction of DNA Oligomers

Highly porous polypyrrole (PPy)-nanocellulose paper sheets have been evaluated as inexpensive and disposable electrochemically controlled three-dimensional solid phase extraction materials. The composites, which had a total anion exchange capacity of about 1.1 mol kg−1, were used for extraction and subsequent release of negatively charged fluorophore tagged DNA oligomers via galvanostatic oxidation and reduction of a 30–50 nm conformal PPy layer on the cellulose substrate. The ion exchange capacity, which was, at least, two orders of magnitude higher than those previously reached in electrochemically controlled extraction, originated from the high surface area (i.e. 80 m2 g−1) of the porous composites and the thin PPy layer which ensured excellent access to the ion exchange material. This enabled the extractions to be carried out faster and with better control of the PPy charge than with previously employed approaches. Experiments in equimolar mixtures of (dT)6, (dT)20, and (dT)40 DNA oligomers showed that all oligomers could be extracted, and that the smallest oligomer was preferentially released with an efficiency of up to 40% during the reduction of the PPy layer. These results indicate that the present material is very promising for the development of inexpensive and efficient electrochemically controlled ion-exchange membranes for batch-wise extraction of biomolecules

Common Inherited Variation in Mitochondrial Genes Is Not Enriched for Associations with Type 2 Diabetes or Related Glycemic Traits

Mitochondrial dysfunction has been observed in skeletal muscle of people with diabetes and insulin-resistant individuals. Furthermore, inherited mutations in mitochondrial DNA can cause a rare form of diabetes. However, it is unclear whether mitochondrial dysfunction is a primary cause of the common form of diabetes. To date, common genetic variants robustly associated with type 2 diabetes (T2D) are not known to affect mitochondrial function. One possibility is that multiple mitochondrial genes contain modest genetic effects that collectively influence T2D risk. To test this hypothesis we developed a method named Meta-Analysis Gene-set Enrichment of variaNT Associations (MAGENTA; http://www.broadinstitute.org/mpg/magenta). MAGENTA, in analogy to Gene Set Enrichment Analysis, tests whether sets of functionally related genes are enriched for associations with a polygenic disease or trait. MAGENTA was specifically designed to exploit the statistical power of large genome-wide association (GWA) study meta-analyses whose individual genotypes are not available. This is achieved by combining variant association p-values into gene scores and then correcting for confounders, such as gene size, variant number, and linkage disequilibrium properties. Using simulations, we determined the range of parameters for which MAGENTA can detect associations likely missed by single-marker analysis. We verified MAGENTA's performance on empirical data by identifying known relevant pathways in lipid and lipoprotein GWA meta-analyses. We then tested our mitochondrial hypothesis by applying MAGENTA to three gene sets: nuclear regulators of mitochondrial genes, oxidative phosphorylation genes, and ∼1,000 nuclear-encoded mitochondrial genes. The analysis was performed using the most recent T2D GWA meta-analysis of 47,117 people and meta-analyses of seven diabetes-related glycemic traits (up to 46,186 non-diabetic individuals). This well-powered analysis found no significant enrichment of associations to T2D or any of the glycemic traits in any of the gene sets tested. These results suggest that common variants affecting nuclear-encoded mitochondrial genes have at most a small genetic contribution to T2D susceptibility

Copy Number Variation in Intron 1 of SOX5 Causes the Pea-comb Phenotype in Chickens

Pea-comb is a dominant mutation in chickens that drastically reduces the size of the comb and wattles. It is an adaptive trait in cold climates as it reduces heat loss and makes the chicken less susceptible to frost lesions. Here we report that Pea-comb is caused by a massive amplification of a duplicated sequence located near evolutionary conserved non-coding sequences in intron 1 of the gene encoding the SOX5 transcription factor. This must be the causative mutation since all other polymorphisms associated with the Pea-comb allele were excluded by genetic analysis. SOX5 controls cell fate and differentiation and is essential for skeletal development, chondrocyte differentiation, and extracellular matrix production. Immunostaining in early embryos demonstrated that Pea-comb is associated with ectopic expression of SOX5 in mesenchymal cells located just beneath the surface ectoderm where the comb and wattles will subsequently develop. The results imply that the duplication expansion interferes with the regulation of SOX5 expression during the differentiation of cells crucial for the development of comb and wattles. The study provides novel insight into the nature of mutations that contribute to phenotypic evolution and is the first description of a spontaneous and fully viable mutation in this developmentally important gene

Mutations in or near the Transmembrane Domain Alter PMEL Amyloid Formation from Functional to Pathogenic

PMEL is a pigment cell-specific protein that forms physiological amyloid fibrils upon which melanins ultimately deposit in the lumen of the pigment organelle, the melanosome. Whereas hypomorphic PMEL mutations in several species result in a mild pigment dilution that is inherited in a recessive manner, PMEL alleles found in the Dominant white (DW) chicken and Silver horse (HoSi)—which bear mutations that alter the PMEL transmembrane domain (TMD) and that are thus outside the amyloid core—are associated with a striking loss of pigmentation that is inherited in a dominant fashion. Here we show that the DW and HoSi mutations alter PMEL TMD oligomerization and/or association with membranes, with consequent formation of aberrantly packed fibrils. The aberrant fibrils are associated with a loss of pigmentation in cultured melanocytes, suggesting that they inhibit melanin production and/or melanosome integrity. A secondary mutation in the Smoky chicken, which reverts the dominant DW phenotype, prevents the accumulation of PMEL in fibrillogenic compartments and thus averts DW–associated pigment loss; a secondary mutation found in the Dun chicken likely dampens a HoSi–like dominant mutation in a similar manner. We propose that the DW and HoSi mutations alter the normally benign amyloid to a pathogenic form that antagonizes melanosome function, and that the secondary mutations found in the Smoky and Dun chickens revert or dampen pathogenicity by functioning as null alleles, thus preventing the formation of aberrant fibrils. We speculate that PMEL mutations can model the conversion between physiological and pathological amyloid

Ergebnisse nach Transkatheter-Aortenklappenersatz bei älteren Patienten

$\bf Background$ The prevalence of aortic valve stenosis is increasing due to the continuously growing geriatric population. Data on procedural success and mortality of very old patients are sparse, raising the question of when this population may be deemed as "too old even for transcatheter aortic valve replacement (TAVR)". We, therefore, sought to evaluate the influence of age on outcome after TAVR and the impact of direct implantation. $\bf Methods$ The data of 394 consecutive patients undergoing TF-TAVR were analyzed. Patients were divided into four age groups: ≤75 (group 1, $\it n$ = 28), 76–80 (group 2, $\it n$ = 107), 81–85 (group 3, $\it n$ = 148), and >85 (group 4, $\it n$ = 111) years. Direct implantation was performed when possible according to current recommendations. Survival was evaluated by Kaplan–Meier analysis. $\bf Results$ Mortality at 30 days and 1 year was not significantly different between the four age groups (3.6 vs. 6.7 vs. 5.4 vs. 2.7% and 7.6 vs. 17 vs. 14.5 vs. 13%m respectively, log-rank $\it p$ = 0.59). Direct implantation without balloon aortic valvuloplasty was more frequently performed on patients aged >85 vs. ≤85 years (33.3 vs. 14.1%, $\it p$ < 0.001). the incidence of procedural complications frequently associated with advanced age (stroke, vascular complications) was not significantly increased in group 4. \ (\bf Conclusion\) Outcome after TF-TAVR is comparable among different age cohorts, even in very old patients. Direct implantation simplifies the procedure and could therefore play a role in reducing the incidence of peri-interventional complications in patients of advanced age.$\bf Hintergrund$ Die Prävalenz der Aortenklappenstenose steigt durch eine kontinuierlich wachsende geriatrische Bevölkerung. Daten über prozeduralen Erfolg sowie Mortalität von sehr alten Patienten sind gering, sodass sich die Frage stellt, wann diese Population "als bereits zu alt" für einen Transkatheter-Aortenklappenersatz (TAVR) anzusehen wäre. Ziel dieser Studie war es, den Einfluss der direkten Implantation auf die Ergebnisse nach transfemoraler (TF-)TAVR bei Patienten in fortgeschrittenem Alter zu evaluieren. $\bf Methoden$ Dazu wurden die Daten von 394 konsekutiven Patienten nach TF-TAVR ermittelt. Die Patienten wurden in 4 Altersgruppen eingeteilt: ≤75 Jahre (Gruppe 1, $\it n$ = 28), 76–80 Jahre (Gruppe 2, $\it n$ = 107), 81–85 Jahre (Gruppe 3, $\it n$ = 148) und >85 Jahre (Gruppe 4, $\it n$ = 111). Sofern es die aktuellen Empfehlungen erlaubten, wurde eine direkte Implantation durchgeführt. Das Überleben wurde mittels Kaplan–Meier-Analyse evaluiert. $\bf Ergebnisse$ Zwischen den 4 Altersgruppen waren keine signifikanten Unterschiede der Mortalität nach 30 Tagen und nach einem Jahr zu verzeichnen (entsprechend 3,6 vs. 6,7 vs. 5,4 vs. 2,7 % und 7,6 vs. 17 vs. 14,5 vs. 13 %; $\it p$ = 0,59 für Log-Rank-Test). Eine direkte Implantation ohne Ballonvalvuloplastie wurde bei Patienten >85 Jahre häufiger durchgeführt als ≤85 Jahre (33,3 vs. 14,1 %; $\it p$ < 0,001). Die Inzidenz von häufig mit fortgeschrittenem Patientenalter assoziierten prozeduralen Komplikationen (Schlaganfall, vaskuläre Komplikationen) war in der Gruppe 4 nicht signifikant erhöht. $\bf Schlussfolgerung$ In verschiedenen Alterskollektiven zeigen sich vergleichbare Ergebnisse nach TF-TAVR, dies gilt sogar für Patienten sehr hohen Alters. Die direkte Implantation kann die Prozedur vereinfachen und zu einer konsekutiven Reduktion der Inzidenz von periprozeduralen Komplikationen bei Patienten mit fortgeschrittenem Alter führen