The characterization of a zebrafish mid‐hindbrain mutant,mid‐hindbrain gone (mgo)

The vertebrate mid‐hindbrain boundary (MHB) is a crucial morphological structure required for patterning and neural differentiation of the midbrain and anterior hindbrain. We isolated a novel zebrafish mutant, MHB gone (mgo), that exhibited a defective MHB. Expression of engrailed3 in the prospective MHB was absent at the 1‐somite stage, suggesting that initiation of the isthmic organizer was disrupted in mgo mutants. Complementation test with mgo and noi, in which the pax2a gene is mutated, infer that the mgo mutant may represent a novel noi allele. However, pronephric, otic vesicle, and commissural axonal defects described in noi mutants were not associated with mgo mutants. Genetic mapping revealed that the mgo mutation is linked to the Pax2a locus, but no mutation was detected in pax2a exons or within intron‐exon boundaries. Based on these findings, we propose that the mgo mutation genetically interacts with pax2a required for the initiation of MHB formation. Developmental Dynamics 238:899–907, 2009. © 2009 Wiley‐Liss, Inc.     

Roundabout 4 is expressed on hematopoietic stem cells and potentially involved in the niche-mediated regulation of the side population phenotype

Roundabout (Robo) family proteins are immunoglobulin-type cell surface receptors that are expressed predominantly in the nervous system. The fourth member of this family, Robo4, is distinct from the other family members in that it is expressed specifically in endothelial cells. In this study, we examined the expression of Robo4 in hematopoietic stem cells (HSCs) and its possible role in HSC regulation. Robo4 mRNA was specifically expressed in murine HSCs and the immature progenitor cell fraction but not in lineage-positive cells or differentiated progenitors. Moreover, flow cytometry showed a correlation between higher expression of Robo4 and immature phenotypes of hematopoietic cells. Robo4(high) hematopoietic stem/progenitor cells presented higher clonogenic activity or long-term repopulating activity by colony assays or transplantation assays, respectively. A ligand for Robo4, Slit2, is specifically expressed in bone marrow stromal cells, and its expression was induced in osteoblasts in response to myelosuppressive stress. Interestingly, overexpression of Robo4 or Slit2 in HSCs resulted in their decreased residence in the c-Kit(+)Sca-1(+)Lineage(-)-side population fraction. These results indicate that Robo4 is expressed in HSCs, and Robo4/Slit2 signaling may play a role in HSC homeostasis in the bone marrow niche.     

Characterization and role of NUMB in the human extravillous trophopblast

NUMB is a multifunctional protein involved in asymmetric cell differentiation, proliferation and maintenance. Four mammalian NUMB isoforms have been identified, which utilize the phosphotyrosine binding (PTB) domain and the proline rich region (PRR) domain to regulate cell growth and differentiation in the developing nervous system. The observation that a decrease in spongiotrophoblast number and thickness of placentae of null (Numb^−/−) mouse embryos, which died at E10.5, suggests NUMB may play a role in placental development. In this study, we demonstrated for the first time, that NUMB isoforms 1, 2, 3, and 4 are present in the human placenta and the human extravillous trophoblast (EVT) cell line HTR8/SVneo. We report three novel isoforms, NUMB 7, 8, and 9, identified by cloning of RT-PCR products and sequencing. Corresponding sequences of novel isoforms were submitted to genebank (accession numbers for each new isoform: NUMB 7- EU265736, NUMB 8- EU265737 and NUMB 9-EU265738). Western blot analysis confirmed the presence of all NUMB isofoms in human placental samples in all trimesters and in EVT cells. NUMB immunosignals were extensively localized in human extravillous trophoblasts and decidual cells at the maternal-fetal interface. NUMB 8 appeared to be the predominant isoform in placental villi. Furthermore, cell migration studies revealed NUMB isoform 1 to be involved in EVT cell migration and NUMB isoforms 2 and 4 to induce EVT apoptosis.     

Microglandular adenosis: a prime suspect in triple‐negative breast cancer development

Microglandular adenosis (MGA) and atypical MGA (AMGA) are unusual lesions of the breast. They were once regarded as benign proliferative lesions and innocent bystanders. Several lines of evidence suggested that they could be neoplastic, clonal lesions and a non‐obligate precursor for triple‐negative breast cancers (TNBC). Recent work published in The Journal of Pathology by Guerini‐Rocco and colleagues provided further evidence regarding the precursor–product relationship between MGA/AMGA and TNBC. Using a massively parallel sequencing approach, they demonstrated that MGA/AMGA, particularly those associated with TNBC, could be clonal neoplastic lesions showing clonal non‐synonymous mutations, but none in pure MGA. Importantly, those alterations were observed in the associated TNBC. They were also able to identify recurrent alterations in TP53 in those MGA/AMGA cases as well as their associated TNBC. The findings, in conjunction with others, underscore the significance for MGA in clinical diagnosis. The potential of a benign lesion to progress into an aggressive malignant tumour implies that modification of the current management approach may be necessary. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Introduction of new clones of penicillin-nonsusceptible Streptococcus pneumoniae in Hong Kong

Analysis of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) isolates in Hong Kong by use of a combination of antibiogram typing, serotyping, multilocus sequence typing, and pulsed-field gel electrophoresis indicated that the dissemination of PNSP was the result of the spread of international clones: variants of the Spain(23F)-1 or Spain(6B)-2 clones were the predominant PNSP isolates from 1994 to 1997 and remained so, but Taiwan(19F)-14 and Taiwan serotype 6B clones were disseminated in Hong Kong in 1999 and 2000. Concomitant changes in antibiotic susceptibility profiles, with the rate of susceptibility to chloramphenicol rising from 10% in the period from 1994 to 1997 to 31% (P < 0.001) in 1999 and 2000, were noted to accompany the shift of clones.     

MAPK signaling has stage-dependent osteogenic effects on human adipose-derived stem cells in vitro

Overview: The use of pro-osteogenic growth factors, such as BMP2, in human adipose-derived stem cell (ASC) osteogenesis is well described. Because these growth factors work via signal transduction pathways, such as the mitogen-activated protein kinase (MAPK) cascade, a study of the relationship between MAPK signaling and ASC osteogenesis was conducted. Materials and Methods: ERK, JNK, and p38MAPK activation were measured in ASCs osteo-induced using either dexamethasone or vitamin D3 and correlated with mineralization. Activation and mineralization were also measured without dexamethasone or using the glucocorticoid, cortisone. The expression of the MAPK phosphatase, MKP1, and its relationship to mineralization was also assessed. The effect of decreasing MAPK activation on mineralization through the use of exogenous inhibitors was examined along with siRNA-knockdown and adenoviral overexpression of ERK1/2. Finally, the effect of ERK1/2 overexpression on ASCs induced on PLGA scaffolds was assessed. Results: ASC mineralization in dexamethasone or vitamin D3-induced ASCs correlated with both increased ERK1/2 and JNK1/2 activation. ASCs induced without dexamethasone also mineralized, with JNK1/2 signaling possibly mediating this event. No link between cortisone induction and MAPK signaling could be ascertained. ASCs treated with ERK, JNK, or p38MAPK inhibitors showed decreased osteogenic gene expression and diminished mineralization. Mineralization levels were also affected by viruses designed to inhibit or augment ERK1/2 expression and activity. Finally, ASC mineralization appeared to be a balance between the MAPK kinase activity and MKP1. Conclusions: It is likely that MAPK signaling plays a significant role in ASC osteogenesis, affecting differentiation in kinase- and stage-specific manners.     

A characteristic syndrome associated with microduplication of 8q12, inclusive of CHD7

This report describes a 4 year-old girl with history of hypotonia, developmental delay, and failure to thrive in infancy. She has cognitive impairment and multiple congenital anomalies, including Duane anomaly, Mondini malformation with associated deafness, external ear malformations, and atrial and ventricular septal defects. Array comparative genomic hybridization demonstrated a de novo tandem 6.9 Mb duplication of at least 15 genes in chromosome 8q12, inclusive of CHD7, with breakpoints at 58,388,614 bp and 65,306,097 bp (NCBI build 36.1). Loss of CHD7 by microdeletion or intragenic mutation causes CHARGE syndrome. There is one previous report of an individual with microduplication of 8q12 involving CHD7. He also had early hypotonia, cognitive impairment, Duane anomaly, sensorineural deafness and a congenital heart defect. This rather specific recurrent pattern of congenital anomalies associated with overlapping duplications of the genomic region containing CHD7 suggests that the phenotype in these two patients may be the result of abnormal CHD7 dosage.     

Adverse events recorded in English primary care: observational study using the General Practice Research Database

Background

More accurate and recent estimates of adverse events in primary care are necessary to assign resources for improvement of patient safety, while predictors must be identified to ameliorate patient risk.

Aim

To determine the incidence of recorded iatrogenic harm in general practice and identify risk factors for these adverse events.

Design and setting

Cross-sectional sample of 74 763 patients at 457 English general practices between 1 January 1999 and 31 December 2008, obtained from the General Practice Research Database.

Method

Patient age at study entry, sex, ethnicity, deprivation, practice region, duration registered at practice, continuity of care, comorbidities, and health service use were extracted from the data. Adverse events were defined by Read Codes for complications of care (Chapters S, T, and U). Crude and adjusted analyses were performed by Poisson regression, using generalised estimating equations.

Results

The incidence was 6.0 adverse events per 1000 person-years (95% confidence interval [CI] = 5.74 to 6.27), equivalent to eight adverse events per 10 000 consultations (n = 2 540 877). After adjustment, patients aged 65–84 years (risk ratio [RR] = 5.62, 95% CI = 4.58 to 6.91; P<0.001), with the most consultations (RR = 2.14, 95% CI = 1.60 to 2.86; P<0.001), five or more emergency admissions (RR = 2.08, 95% CI = 1.66 to 2.60; P<0.001), or the most diseases according to expanded diagnosis clusters (RR = 8.46, 95% CI = 5.68 to 12.6; P<0.001) were at greater risk of adverse events. Patients registered at their practice for the longest periods of time were less at risk of an adverse event (RR = 0.40, 95% CI = 0.35 to 0.47; P<0.001).

Conclusion

The low incidence of recorded adverse events is comparable with other studies. Temporal sequencing of risk factors and case ascertainment would benefit from data triangulation. Future studies may explore whether first adverse events predict future incidents.     

Outbreak of serogroup C meningococcal disease caused by a variant of Neisseria meningitidis serotype 2a ET-15 in a community of men who have sex with men

We describe an outbreak, in a community of men who have sex with men, of serogroup C meningococcal disease caused by a genetic variant of the serotype 2a ET-15 Neisseria meningitidis characterized by a point mutation in the gene coding for the serotype 2a antigen. A microbiological characterization of the outbreak strain is presented in this report.