Noncommutative Particles in Curved Spaces

We present a formulation in a curved background of noncommutative mechanics, where the object of noncommutativity $\theta^{\mu\nu}$ is considered as an independent quantity having a canonical conjugate momentum. We introduced a noncommutative first-order action in D=10 curved spacetime and the covariant equations of motions were computed. This model, invariant under diffeomorphism, generalizes recent relativistic results.Comment: 1+15 pages. Latex. New comments and results adde

A landmark-free morphometrics pipeline for high-resolution phenotyping: application to a mouse model of Down syndrome

Characterising phenotypes often requires quantification of anatomical shape. Quantitative shape comparison (morphometrics) traditionally uses manually located landmarks and is limited by landmark number and operator accuracy. Here, we apply a landmark-free method to characterise the craniofacial skeletal phenotype of the Dp1Tyb mouse model of Down syndrome and a population of the Diversity Outbred (DO) mouse model, comparing it with a landmark-based approach. We identified cranial dysmorphologies in Dp1Tyb mice, especially smaller size and brachycephaly (front-back shortening), homologous to the human phenotype. Shape variation in the DO mice was partly attributable to allometry (size-dependent shape variation) and sexual dimorphism. The landmark-free method performed as well as, or better than, the landmark-based method but was less labour-intensive, required less user training and, uniquely, enabled fine mapping of local differences as planar expansion or shrinkage. Its higher resolution pinpointed reductions in interior mid-snout structures and occipital bones in both the models that were not otherwise apparent. We propose that this landmark-free pipeline could make morphometrics widely accessible beyond its traditional niches in zoology and palaeontology, especially in characterising developmental mutant phenotypes

Ultra-Rare Genetic Variation in the Epilepsies : A Whole-Exome Sequencing Study of 17,606 Individuals

Sequencing-based studies have identified novel risk genes associated with severe epilepsies and revealed an excess of rare deleterious variation in less-severe forms of epilepsy. To identify the shared and distinct ultra-rare genetic risk factors for different types of epilepsies, we performed a whole-exome sequencing (WES) analysis of 9,170 epilepsy-affected individuals and 8,436 controls of European ancestry. We focused on three phenotypic groups: severe developmental and epileptic encephalopathies (DEEs), genetic generalized epilepsy (GGE), and non-acquired focal epilepsy (NAFE). We observed that compared to controls, individuals with any type of epilepsy carried an excess of ultra-rare, deleterious variants in constrained genes and in genes previously associated with epilepsy; we saw the strongest enrichment in individuals with DEEs and the least strong in individuals with NAFE. Moreover, we found that inhibitory GABA(A) receptor genes were enriched for missense variants across all three classes of epilepsy, whereas no enrichment was seen in excitatory receptor genes. The larger gene groups for the GABAergic pathway or cation channels also showed a significant mutational burden in DEEs and GGE. Although no single gene surpassed exome-wide significance among individuals with GGE or NAFE, highly constrained genes and genes encoding ion channels were among the lead associations; such genes included CACNAIG, EEF1A2, and GABRG2 for GGE and LGI1, TRIM3, and GABRG2 for NAFE. Our study, the largest epilepsy WES study to date, confirms a convergence in the genetics of severe and less-severe epilepsies associated with ultra-rare coding variation, and it highlights a ubiquitous role for GABAergic inhibition in epilepsy etiology.Peer reviewe

A spuriously 'normal' haemoglobin A1c result

Case reportWe report a case of spuriously 'normal' haemoglobin A1c (HbA1c) result due to misidentification of HbG Taipei as HbAo by the Variant II built-in retention time algorithm. The defect was circumvented effectively by the implementation of a chromatographic system specific internal quality control mechanism for peak identity verification. HbA1c and estimated average glucose results were corrected from 4.7% to 8.2%, and 4.9 to 10.5 mmol/L, respectively. The results were consistent with the patient's concurrent and previous fasting blood glucose concentrations and existence of diabetes mellitus dermopathy, indicating poor glycaemic control. A review of currently available analytical systems showed that other than mass spectrometry, HbA1c measurements by these systems were generally affected by the presence of haemoglobin variants. The same haemoglobin variant may affect different analytical systems differently, resulting in the deviation of HbA1c results from the true value to different extents. Including the analytical principle of HbA1c measurement in the laboratory report can avoid inappropriate comparison of results obtained by different analytical systems. Moreover, since individual haemoglobinopathy may affect the degree of glucose binding to haemoglobin in a different way, this uncertainty limits the general application of same decision cut-off of established guidelines for glycaemic control monitoring. Adoption of an individualized monitoring system based on the critical difference or reference change value of HbA1c can be considered.link_to_OA_fulltex

Effects of blood-processing protocols on fetal and total DNA quantification in maternal plasma

Background: Recently, apoptotic cells have been found in plasma obtained by centrifugation of blood from pregnant women, raising the question of what constitutes plasma and whether plasma is truly cell free. We compared the effects of different blood-processing protocols on the quantification, DNA composition, and day-to-day fluctuation of fetal and total DNA in maternal plasma. Methods: Blood samples were collected from healthy pregnant women. The blood sample from each individual was simultaneously processed by different means, including the following: Percoll separation, centrifugation, microcentrifugation, and filtration. The resulting plasma aliquots were subjected to real-time quantitative amplification of the β-globin (for total DNA) and SRY (for fetal DNA) genes. The differences in the β-globin and SRY DNA concentrations and the degree of variation between the various plasma aliquots were assessed statistically. Results: Different protocols of blood processing significantly affected the quantification and the day-to-day fluctuation of total (P <0.001), but not fetal (quantification, P = 0.336; fluctuation, P = 0.206), DNA in maternal plasma. The quantitative difference could be attributed to the fact that efficacies of different protocols for generating cell-free plasma vary. Processing blood samples by centrifugation followed by filtration or microcentrifugation is effective in producing cell-free plasma. Conclusions: Standardization in plasma-processing protocols is needed for maternal plasma DNA analysis, especially for quantification of total DNA in maternal plasma. Such preanalytic factors may also affect other applications of plasma DNA analysis. © 2001 American Association for Clinical Chemistry.link_to_subscribed_fulltex

Concomitant Eber-Positive Lymphomatoid Papulosis and Malignant Transformation of Colonic Polyposis in a Heart Transplant Recipient

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Predictors of 3-month continuous abstinence from cigarette smoking among Chinese smokers treated in a smoking cessation health centre

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Implementation of a clinic based smoking cessation service in Hong Kong

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Post-transplantation lymphoproliferative disease in Chinese: The Queen Mary Hospital experience in Hong Kong

Post-transplantation lymphoproliferative disease (PTLD) is an unique iatrogenic complication after bone marrow transplantation (BMT) and solid organ transplantation (SOTx). The pattern of EBV related lymphoma in Chinese is different from Caucasians. We surveyed the incidence, clinical and pathological spectrum of PTLD among 541 cases of allogeneic BMT, 145 cases of renal transplant, 35 cases of heart/lung transplantation and 146 cases of orthotopic liver transplantation (OLT). From 1994 to 2001, 13 consecutive cases of PTLD were diagnosed, ranging from disseminated NK cell lymphoma to localized plasmacytoma. Both donor and recipient derived PTLD was documented. Disease was often heralded by cytomegaloviral disease and antithymocyte globulin (ATG) usage. Two cases were diagnosed post-mortem, and six patients died of PTLD at a median of 3 months. Complete and partial remission was only achieved in 3 and 2 cases, respectively, despite a range of treatment (reduced immuosuppression, explantation, radiotherapy, combination chemotherapy, donor lymphocytes, autologous marrow infusion and rituximab). Most responding patients died subsequently of rejection, infection and graft versus host disease (GVHD). The incidence of PTLD is not increased in Chinese patients. However, some patients may be at increased risk, especially mismatched allogeneic BMT, parental OLT (especially involving young infants) and heavy ATG exposure.link_to_subscribed_fulltex