Identification of a candidate tumour suppressor gene, MMAC1, at chromosome 10q23.3 that is mutated in multiple advanced cancers

Deletions involving regions of chromosome 10 occur in the vast majority (> 90%) of human glioblastoma multiformes. A region at chromosome 10q23-24 was implicated to contain a tumour suppressor gene and the identification of homozygous deletions in four glioma cell lines further refined the location. We have identified a gene, designated MMAC1, that spans these deletions and encodes a widely expressed 5.5-kb mRNA. The predicted MMAC1 protein contains sequence motifs with significant homology to the catalytic domain of protein phosphatases and to the cytoskeletal proteins, tensin and auxilin. MMAC1 coding-region mutations were observed in a number of glioma, prostate, kidney and breast carcinoma cell lines or tumour specimens. Our results identify a strong candidate tumour suppressor gene at chromosome 10q23.3, whose loss of function appears to be associated with the oncogenesis of multiple human cancers.

Very delayed infarction after mild focal cerebral ischemia: a role for apoptosis?

The temporal evolution of cerebral infarction was examined in rats subjected to transient occlusion of both common carotid arteries and the right middle cerebral artery. After severe (90-min) ischemia, substantial right-sided cortical infarction was evident within 6 h and fully developed after 1 day. After mild (30-min) ischemia, no cortical infarction was present after 1 day. However, infarction developed after 3 days; by 2 weeks, infarction volume was as large as that induced by 90-min ischemia. These data suggest that infarction after mild focal ischemia can develop in a surprisingly delayed fashion. Some evidence of neuronal apoptosis was present after severe ischemia, but only to a limited degree. However, 3 days after mild ischemia, neurons bordering the maturing infarction exhibited prominent TUNEL staining, and DNA prepared from the periinfarct area of ischemic cortex showed internucleosomal fragmentation. Furthermore, pretreatment with 1 mg/kg cycloheximide markedly reduced infarction volume 2 weeks after mild ischemia. These data raise the possibility that apoptosis, dependent on active protein synthesis, contributes to the delayed infarction observed in rats subjected to mild transient focal cerebral ischemia.

A candidate prostate cancer susceptibility gene at chromosome 17p

It is difficult to identify genes that predispose to prostate cancer due to late age at diagnosis, presence of phenocopies within high-risk pedigrees and genetic complexity. A genome-wide scan of large, high-risk pedigrees from Utah has provided evidence for linkage to a locus on chromosome 17p. We carried out positional cloning and mutation screening within the refined interval, identifying a gene, ELAC2, harboring mutations (including a frameshift and a nonconservative missense change) that segregate with prostate cancer in two pedigrees. In addition, two common missense variants in the gene are associated with the occurrence of prostate cancer. ELAC2 is a member of an uncharacterized gene family predicted to encode a metal-dependent hydrolase domain that is conserved among eukaryotes, archaebacteria and eubacteria. The gene product bears amino acid sequence similarity to two better understood protein families, namely the PSO2 (SNM1) DNA interstrand crosslink repair proteins and the 73-kD subunit of mRNA 3' end cleavage and polyadenylation specificity factor (CPSF73).

Epidemiology of incident spinal fracture in a complete population

STUDY DESIGN

Cross-section observational study of incident spinal fractures using an administrative data-base.

OBJECTIVES

To identify and define all patients who have spinal fractures within a complete population.

SUMMARY OF BACKGROUND DATA

The true incidence of spinal column and cord injury is not known. Previous studies have been institutional or practice based. Accurate information concerning the magnitude of the spinal injury population and their characteristics may provide more rational basis for public health decision making and resource allocation.

METHODS

The study dates were April 1, 1981 to March 31, 1984. Using the Manitoba Health Services Insurance Plan database, all patients with ICD-9-CM coding of 805.x and 806.x (spinal column fracture with and without spinal cord injury) were identified. Incidence rates, age and gender distribution, and ambulatory and hospital contracts were identified. Hospital discharge abstracts were used to classify mechanisms of injury, associated injuries, and length of stay.

RESULT

The annual incidence rate of spinal fracture was 64 per 100,000. Two thousand sixty-three patients were identified, with 944 being admitted to the hospital. There were two peaks of incidence occurring in young men and elderly women. Of the hospitalized patients, 182 had cervical injury, 286 had thoracic fracture, and 403 had injury in the lumbosacral spine Associated injuries occurred in 38% of hospitalized patients. Length of stay was an average of 38.5 days. Overall mortality was 41%. Neurologic injury occurred in 122 patients.

CONCLUSIONS

Ambulatory care of spine injuries is more common than hospital care. Two peaks of incidence occur-in young men and elderly women. Future decisions for research, public health policy, and resource allocation can be based on these data.

Induction of xenobiotic enzymes by the MAP kinase pathway and the antioxidant or electrophile response element (ARE/EpRE)

Cellular responses to xenobiotic-induced stress can signal proliferation, differentiation, homeostasis, apoptosis, or necrosis. To better understand the underlying molecular mechanisms after exposure to xenobiotics or drugs, we studied the signal transduction pathways, the mitogen-activated protein kinase (MAPK), and the basic leucine zipper transcription factor Nrf2, activated by different agents in the induction of Phase II drug metabolizing enzymes (DMEs). The MAPKs, characterized as proline-directed serine/threonine kinases, are essential components of signaling pathways that convert various extracellular signals into intracellular responses through serial phosphorylation cascades. Once activated, MAPKs can phosphorylate many transcription factors, such as c-Jun, ATF-2, and ultimately lead to changes in gene expression. Two classes of Phase II gene inducers, which are also cancer chemopreventive agents, were studied: (1) the phenolic antioxidants, namely butylated hydroxyanisole (BHA) and its active de-methylated metabolite t-butylhydroquinone (tBHQ), and phenolic flavonoids such as green tea polyphenols (GTP) and (-)-epigallocatechin-3-gallate (EGCG); and (2) the naturally occurring isothiocyanates, namely phenethyl isothiocyanate (PEITC), and sulforaphane. BHA and tBHQ are both well-known phenolic antioxidants used as food preservatives, and strongly activate c-Jun N-terminal kinase 1 (JNK1), extracellular signal-regulated protein kinase 2 (ERK2), or p38, in a time- and dose-dependent fashion. Free radical scavengers N-acetyl-L-cysteine (NAC), or glutathione (GSH), inhibited ERK2 activation and, to a much lesser extent, JNK1 activation by BHA/tBHQ, implicating the role of oxidative stress. Under conditions where MAPKs were activated, BHA or GTP also activated ARE/EpRE (antioxidant/electrophile response element), with the induction of Phase II genes such as NQO. Transfection studies with various cDNAs encoding wild-type or dominant-negative mutants of MAPKs and/or transcription factor Nrf2, substantially modulated ARE-mediated luciferase reporter activity in the presence or absence of phenolic compounds. Other phytochemicals including PEITC, and sulforaphane, also differentially regulated the activities of MAPKs, Nrf2, and ARE-mediated luciferase reporter gene activity and Phase II enzyme induction. A model is proposed where these xenobiotics (BHA, tBHQ, GTP, EGCG, PEITC, sulforaphane) activate the MAPK pathway via an electrophilic-mediated stress response, leading to the transcription activation of Nrf2/Maf heterodimers on ARE/EpRE enhancers, with the subsequent induction of cellular defense/detoxifying genes including Phase II DMEs, which may protect the cells against toxic environmental insults and thereby enhance cell survival. The studies of these signaling pathways may yield insights into the fate of cells upon exposure to xenobiotics.

Association of genetic variation in FTO with risk of obesity and type 2 diabetes with data from 96,551 East and South Asians

AIMS/HYPOTHESIS

FTO harbours the strongest known obesity-susceptibility locus in Europeans. While there is growing evidence for a role for FTO in obesity risk in Asians, its association with type 2 diabetes, independently of BMI, remains inconsistent. To test whether there is an association of the FTO locus with obesity and type 2 diabetes, we conducted a meta-analysis of 32 populations including 96,551 East and South Asians.

METHODS

All studies published on the association between FTO-rs9939609 (or proxy [r (2) > 0.98]) and BMI, obesity or type 2 diabetes in East or South Asians were invited. Each study group analysed their data according to a standardised analysis plan. Association with type 2 diabetes was also adjusted for BMI. Random-effects meta-analyses were performed to pool all effect sizes.

RESULTS

The FTO-rs9939609 minor allele increased risk of obesity by 1.25-fold/allele (p = 9.0 × 10(-19)), overweight by 1.13-fold/allele (p = 1.0 × 10(-11)) and type 2 diabetes by 1.15-fold/allele (p = 5.5 × 10(-8)). The association with type 2 diabetes was attenuated after adjustment for BMI (OR 1.10-fold/allele, p = 6.6 × 10(-5)). The FTO-rs9939609 minor allele increased BMI by 0.26 kg/m(2) per allele (p = 2.8 × 10(-17)), WHR by 0.003/allele (p = 1.2 × 10(-6)), and body fat percentage by 0.31%/allele (p = 0.0005). Associations were similar using dominant models. While the minor allele is less common in East Asians (12-20%) than South Asians (30-33%), the effect of FTO variation on obesity-related traits and type 2 diabetes was similar in the two populations.

CONCLUSIONS/INTERPRETATION

FTO is associated with increased risk of obesity and type 2 diabetes, with effect sizes similar in East and South Asians and similar to those observed in Europeans. Furthermore, FTO is also associated with type 2 diabetes independently of BMI.

Should calcaneal fractures be treated surgically? A meta-analysis

A MEDLINE search from 1980 through 1996 revealed 1845 articles dealing with calcaneal fractures. Six of these articles that compared operative versus nonoperative treatment for displaced calcaneal fractures met the minimum criteria for inclusion in a meta-analysis. A statistical summary of information across the six articles revealed a trend for surgically treated patients to be more likely to return to the same type of work as compared with nonoperatively treated individuals. There also was a trend for nonoperatively treated patients to have a higher risk of experiencing severe foot pain than did operatively treated patients. Unfortunately, none of the other outcomes could be summarized formally across studies using statistical techniques because of variability in reporting across studies. Although the tendency was always for operatively treated patients to have better outcomes (reaching statistical significance in some of the articles), the strength of evidence to recommend operative treatment for displaced intraarticular calcaneal fractures remains weak. A large prospective randomized controlled trial should be able to answer this question.

Signal transduction events elicited by cancer prevention compounds

Many chemopreventive agents have been shown to modulate gene expression including induction of phase II detoxifying enzymes, such as glutathione S-transferases (GST) and quinone reductases (QR). Induction of phase II enzymes in general leads to protection of cells/tissues against exogenous and/or endogenous carcinogenic intermediates. The antioxidant or electrophile response element (ARE/EpRE) found at the 5'-flanking region of these phase II genes may play important role in mediating their induction by xenobiotics including chemopreventive agents. Members of the basic leucine zipper (bZIP) transcription factor, Nrf2 which heterodimerizes with Maf G/K, are found to bind to the ARE, and transcriptionally-activated ARE. Recently, we showed that the mitogen-activated protein kinases (MAPK) were activated by phase II gene inducers such as phenolic antioxidant butylated hydroxyanisol (BHA) and isothiocyanate sulforaphane (SUL), and involved in the transcription activation of ARE-mediated reporter gene. Transfection studies with wild-type and dominant negative mutants of Nrf2 and MAPK showed synergistic response during co-transfection as well as to phase II gene inducers. However, increasing the concentrations of these compounds such as BHA, the activities of cell death signaling molecules, caspases, were stimulated and resulted in apoptotic cell death. At these concentrations, BHA stimulated loss of mitochondrial membrane potential, cytochrome c release, and activation of caspase 3, 8 and 9 preceding apoptosis. Further increase in concentrations led to rapid cell necrosis. A model is proposed for BHA and SUL, in that at low concentrations, these potential chemopreventive agents may modulate MAPK pathway leading to transcription activation of Nrf2 and ARE with subsequent induction of cellular defensive enzymes including phase II detoxifying enzymes as well as other defensive genes, which may protect the cells against cellular injury, which is a homeostatic response. At higher concentrations, these agents may activate the caspase pathways, leading to apoptosis, a potential beneficial effect if occurs at preneoplastic/neoplastic tissues, but a potential cytotoxic response if occurs in normal tissues. On the other hand, some phenolic compounds such as resveratrol inhibits TPA- or UV-induced AP-1-mediated activity through the inhibition of c-Src non-receptor tyrosine kinase and MAPK pathways. It is possible that in proliferating or stimulated cells, these chemopreventive compounds may block proliferation by inhibiting these signaling kinases, whereas in non-proliferating or quiescent cells, some of these compounds may activate these signaling kinases leading to gene expression of cellular defensive enzymes such as phase II detoxifying enzymes. The studies of these and other signaling pathways may yield insights into the development of potential chemopreventive compounds.

Characterization of immobilization of an enzyme in a modified Y zeolite matrix and its application to an amperometric glucose biosensor

A new approach to construct an amperometric biosensor is described. Without using bovine serum albumin-glutaraldehyde, glucose oxidase (GOx) was immobilized on a dealuminized Y zeolite (DAY)-modified platinum electrode to construct a glucose sensor. The large specific surface area of the zeolite substrate resulted in high enzyme loading. The immobilized GOx in this manner was stable and could maintain its high activity for at least 3 months. The interactions between the zeolite and the enzyme were investigated by means of Fourier transform infrared spectra, and the pore distribution and the surface acid property of DAY were preliminarily studied. The results showed that the hydrophilic property and the existing mesopores of DAY played important roles in the enzyme immobilization. This resulting biosensor exhibited good reproducibility and selectivity, owing to the uniform pore structure and unique ion-exchange property of the zeolite. The biosensor responded rapidly to glucose in the linear range from 2.0 x 10(-6) to 3.0 x 10(-3) M, with a detection limit of 0.5 microM.

Pollutants in Hong Kong soils: polycyclic aromatic hydrocarbons

An extensive soil survey was carried out to study the polycyclic aromatic hydrocarbon (PAH) contaminations in 138 soil samples collected throughout Hong Kong. Results demonstrated that there were low levels of PAH contaminations (median of summation operator 16US EPA PAHs=140 microg kg(-1)) for all land uses (urban park, greening area, country park, rural area, restored landfill, agricultural farmland, orchard farm, crematorium, industrial and near highway area). However, localized hotspots were identified with summation operator 16PAH concentrations as high as 19,500 microg kg(-1) in one urban park. These findings were also confirmed by multivariate analysis. Comparison of PAH profiles showed a widespread domination of its 4-ring member. The major contribution was vehicular emissions from petroleum, and however at the hotspots, the improper disposal of used motor oils. In general, the pollution levels for all the land uses were below the recommended values for residential and general purposes stated in soil quality guidelines such as Netherlands and Denmark except certain identified hotspots. The potential health hazards imposed by these hotspots were alarming, and their existence (3 out of 138 samples) suggested that sole monitoring of atmospheric PAHs may not adequately address the hidden risks to human in urban city.

The nonoperative treatment of burst fractures of the thoracolumbar junction

Treatment of thoracolumbar spine burst fracture with a neurologically intact patient is controversial, with advocates of operative and nonoperative approaches. Of 404 patients in a prospective spinal trauma study, 21 had burst fractures, were neurologically intact, and had greater than 1-year followup. This group was analyzed to evaluate treatment with early mobilization using a thoracolumbar total contact orthosis. The average time in a brace was 6 months. Two patients had pulmonary embolus treated successfully with anticoagulants. No patient required subsequent surgery for increasing kyphosis or neurologic deficit. Change in K angle at followup was 4.6 degrees (+/- 5.7) and change in anterior vertebral height was 6.1 degrees (+/- 10). All patients had a satisfactory pain score and most individuals returned to full employment. It is concluded that it is not necessary to routinely treat patients operatively with burst fractures if they fulfill the following criteria: 1) neurologically intact; 2) kyphosis angle less than 35 degrees; 3) other injuries do not preclude the use of a total contact orthosis; and 4) the patient is capable of understanding and cooperating with the treatment regime. These criteria are irrespective of the CT findings of posterior vertebral retropulsion and spinal canal narrowing.

The role of MMAC1 mutations in early-onset breast cancer: causative in association with Cowden syndrome and excluded in BRCA1-negative cases

Cowden syndrome (CS) is an autosomal dominant disorder associated with the development of hamartomas and benign tumors in a variety of tissues, including the skin, thyroid, breast, endometrium, and brain. It has been suggested that women with CS are at increased risk for breast cancer. A locus for CS was recently defined on chromosome 10 in 12 families, resulting in the identification of the CS critical interval, between the markers D10S215 and D10S541. More recently, affected individuals in four families with CS have been shown to have germ-line mutations in a gene known as "PTEN," or "MMAC1," which is located in the CS critical interval on chromosome 10. In this study, we report three novel MMAC1 mutations in CS and demonstrate that MMAC1 mutations are associated with CS and breast cancer. Furthermore, we also show that certain families and individuals with CS do not have mutations in the coding sequence of MMAC1. Finally, we did not detect MMAC1 mutations in a subpopulation of individuals with early-onset breast cancer, suggesting that germ-line mutations in this gene do not appear to be common in this group.

Binding of human plasminogen and urokinase-type plasminogen activator to the Lyme disease spirochete, Borrelia burgdorferi

Many bacteria that spread in the skin produce enzymes that digest extracellular matrix components. Borrelia burgdorferi spreads from a skin inoculation site to form the characteristic erythema migrans skin lesion. It was determined that B. burgdorferi does not produce collagenase, elastase, hyaluronidase, or other enzymes that digest extracellular matrix components. However, B. burgdorferi bound human plasmin, plasminogen (Pgn), and urokinase-type plasminogen activator (uPA). When spirochetes were sequentially incubated with Pgn and uPA, bioactive plasmin was generated on the surface of B. burgdorferi. B. burgdorferi did not produce an endogenous Pgn activator. Fluorochrome-conjugated uPA and Pgn colocalized to the terminus of the spirochete. In a mouse model, uPA-treated B. burgdorferi were more infectious than control spirochetes. Binding of host uPA and Pgn to form a bioactive extracellular matrix protease on B. burgdorferi represents a mechanism that could facilitate dissemination and localization of spirochetes to sites of vascular injury.

NF-κB and Nrf2 signaling pathways contribute to wogonin-mediated inhibition of inflammation-associated colorectal carcinogenesis

The transcriptional factors nuclear factor-κB (NF-κB) and NF-E2-related factor 2 (Nrf2) have been recently reported to have critical roles in protecting various tissues against inflammation and colitis-associated colorectal cancer (aberrant crypt foci). Our previous studies showed that wogonin (5,7-dihydroxy-8-methoxyflavone) possessed anti-neoplastic and anti-inflammatory activities. The present study extended these important earlier findings by exploring the effect of wogonin on the initiation and development of colitis-associated cancer. Wogonin lowered tumor incidence and inhibited the development of colorectal adenomas in azoxymethane- or dextran sulfate sodium-induced mice. We found that wogonin significantly decreased the secretion and expression of IL-6 and IL-1β, reduced cell proliferation and nuclear expression of NF-κB in adenomas and surrounding tissues and promoted Nrf2 nuclear translocation in surrounding tissues, although overexpressed Nrf2 in tumor tissues was independent of wogonin administration. Furthermore, wogonin inhibited the interaction between human monocytic THP-1 cells and human colon cancer HCT116 cells, and significantly downregulated lipopolysaccharide-induced secretion of prototypical pro-inflammatory cytokines IL-6 and IL-1β in THP-1 cells. Further mechanism research revealed that wogonin inhibited the nuclear translocation of NF-κB and phosphorylation of IκB and IKKα/β, and promoted Nrf2 signaling pathway in HCT116 cells and THP-1 cells. Taken together, the present results indicated that wogonin effectively suppressed inflammation-associated colon carcinogenesis and cancer development, suggesting its potential as a chemopreventive agent against colitis-associated colon cancer.

Metabolic effects of bariatric surgery in type 2 diabetic patients with body mass index < 35 kg/m2

AIM

The aim of this meta-analysis is to assess the metabolic effects of bariatric surgery in type 2 diabetes mellitus (T2DM) patients with body mass index (BMI) < 35 kg/m(2) .

METHODS

We performed an electronic literature search of published articles to identify relevant evidence since inception to June 2011. Primary outcome measures were metabolic improvement and resolution diabetes after bariatric surgery. The weighted mean difference (WMD) and its 95% confidence interval (CI) were calculated from the raw data extracted from the original literature. The software Review Manager (version 4.3.1) was applied for meta-analysis.

RESULTS

Thirteen trials involving 357 patients were included in the meta-analysis. The follow-up interval ranged from 6 months to 18 years. According to WMD calculation, bariatric surgery led to 5.18 kg/m(2) of BMI lowering (95% CI, 3.79-6.57, p < 0.00001), 4.8 mmol/l of fasting plasma glucose (FPG) decrement (95% CI, 3.88-5.71 mmol/l, p < 0.00001), 2.59% of HbA1c decreasing (95% CI, 2.12-3.07%, p < 0.00001), 56.67 mg/dl of triglyceride decrement (95% CI 11.53-101.82, p = 0.01) and 48.38 mg/dl of total cholesterol reduction (95% CI 21.08-75.68, p = 0.0005). Moreover, the procedures produced an increased high-density lipoprotein cholesterol by 5.37 mg/dl (95% CI -11.37-0.63, p = 0.08). However, this effect was not statistically significant. Overall, 80.0% of the patients achieved adequate glycaemic control (HbA1c < 7%) without antidiabetic medication. The surgeries produced a low incidence of major complications (3.2%) with no mortality.

CONCLUSIONS

Bariatric surgery is effectual and safe in the treatment of non-severely obese (BMI < 35 kg/m(2) ) T2DM patients. Moreover, the metabolic benefits acquired from the procedures can be long sustained after the surgery.

Deep-learning-based detection and segmentation of organs at risk in nasopharyngeal carcinoma computed tomographic images for radiotherapy planning

OBJECTIVE

Accurate detection and segmentation of organs at risks (OARs) in CT image is the key step for efficient planning of radiation therapy for nasopharyngeal carcinoma (NPC) treatment. We develop a fully automated deep-learning-based method (termed organs-at-risk detection and segmentation network (ODS net)) on CT images and investigate ODS net performance in automated detection and segmentation of OARs.

METHODS

The ODS net consists of two convolutional neural networks (CNNs). The first CNN proposes organ bounding boxes along with their scores, and then a second CNN utilizes the proposed bounding boxes to predict segmentation masks for each organ. A total of 185 subjects were included in this study for statistical comparison. Sensitivity and specificity were performed to determine the performance of the detection and the Dice coefficient was used to quantitatively measure the overlap between automated segmentation results and manual segmentation. Paired samples t tests and analysis of variance were employed for statistical analysis.

RESULTS

ODS net provides an accurate detection result with a sensitivity of 0.997 to 1 for most organs and a specificity of 0.983 to 0.999. Furthermore, segmentation results from ODS net correlated strongly with manual segmentation with a Dice coefficient of more than 0.85 in most organs. A significantly higher Dice coefficient for all organs together (p = 0.0003 < 0.01) was obtained in ODS net (0.861 ± 0.07) than in fully convolutional neural network (FCN) (0.8 ± 0.07). The Dice coefficients of each OAR did not differ significantly between different T-staging patients.

CONCLUSION

The ODS net yielded accurate automated detection and segmentation of OARs in CT images and thereby may improve and facilitate radiotherapy planning for NPC.

KEY POINTS

• A fully automated deep-learning method (ODS net) is developed to detect and segment OARs in clinical CT images. • This deep-learning-based framework produces reliable detection and segmentation results and thus can be useful in delineating OARs in NPC radiotherapy planning. • This deep-learning-based framework delineating a single image requires approximately 30 s, which is suitable for clinical workflows.

A common variant in MTNR1B, encoding melatonin receptor 1B, is associated with type 2 diabetes and fasting plasma glucose in Han Chinese individuals

AIMS/HYPOTHESIS

Recently, three groups independently reported that variation in MTNR1B, the gene encoding melatonin receptor 1B, was associated with an increased risk of type 2 diabetes, increased fasting plasma glucose and impaired insulin secretion in populations of European ancestry. In the present study, we investigated whether a single MTNR1B polymorphism was associated with type 2 diabetes in Han Chinese individuals, to elucidate whether this is a cross-populational effect.

METHODS

The MTNR1B variant rs10830963 was genotyped in 1,165 type 2 diabetic patients and 1,105 normoglycaemic control individuals of southern Han Chinese ancestry who were residents of the metropolitan area of Shanghai. The risk of developing type 2 diabetes was calculated using a logistic regression model adjusted for age, sex and BMI. A possible association with fasting plasma glucose was analysed in the normoglycaemic control individuals using a multiple linear regression analysis with adjustments for age, sex and BMI.

RESULTS

The genetic variant rs10830963 was associated with an increased risk of type 2 diabetes in our Han Chinese cohort (OR 1.16, 95% CI 1.03-1.31, p = 0.015). As previously described, the risk variant was also associated with increased fasting plasma glucose, showing an increase of 0.068 mmol/l (95% CI 0.036-0.100, p = 4 x 10(-5)) per risk allele.

CONCLUSIONS/INTERPRETATION

A common variant in the MTNR1B gene is associated with an increased risk of type 2 diabetes and increased fasting plasma glucose in Han Chinese, suggesting an important role for this polymorphism in populations of different ethnic and environmental backgrounds.

Molecular sieve mechanism of selective release of cytoplasmic proteins by osmotically shocked Escherichia coli

Escherichia coli cells, the outer membrane of which is permeabilized with EDTA, release a specific subset of cytoplasmic proteins upon a sudden drop in osmolarity in the surrounding medium. This subset includes EF-Tu, thioredoxin, and DnaK among other proteins, and comprises approximately 10% of the total bacterial protein content. As we demonstrate here, the same proteins are released from electroporated E. coli cells pretreated with EDTA. Although known for several decades, the phenomenon of selective release of proteins has received no satisfactory explanation. Here we show that the subset of released proteins is almost identical to the subset of proteins that are able to pass through a 100-kDa-cutoff cellulose membrane upon molecular filtration of an E. coli homogenate. This finding indicates that in osmotically shocked or electroporated bacteria, proteins are strained through a molecular sieve formed by the transiently damaged bacterial envelope. As a result, proteins of small native sizes are selectively released, whereas large proteins and large protein complexes are retained by bacterial cells.

Pedicle morphology of the lower thoracic and lumbar spine in a Chinese population

Knowledge of pedicle diameter and surface landmarks is crucial for safe placement of screws. Little attention has been paid to variations of entrance points for pedicle screws, differentiation of male and female pedicle sizes and pedicle size differences in nonwhite populations. Forty thoracolumbar spinal columns from T9 to L5 were measured using vernier calipers. Cephalad-caudad and medial-lateral diameter of the pedicle, length of the pedicle from posterior cortex to anterior cortex at the midline and parallel to midline was measured. Relation of the centre of the pedicle to the transverse process (TP) and to the superior facet joint was noted. Twenty-five male and 15 female specimens were measured. Average pedicle width in the female was 5.2 mm at T9 (SD 0.9) to 13 mm at L5 (SD 2.7) and in the male 6.0 mm at T9 (SD 1.1) to 12.8 mm at L5 (SD 2.7). Cephalad caudad diameter was 12.5 mm (SD 1.2) at T9 to 20.5 mm (SD 3.6) at L5 in the male and in the female 12.2 mm (SD 1.3) at T9 to 18.7 mm (SD 3.9) at L5. All specimens had starting points cephalad to the midpoint of the TP at T9. At L5, 37 of 40 specimens had starting points at the midpoint of the TP. Starting points were parallel to the middle or lateral third of the superior facet joint at T9. At L5 starting points were at least one third of the facet joint lateral to the lateral border of the facet. Female pedicle width was smaller than male at T9 (P = 0.03) and T12 (P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Genome-wide association study in a Chinese population identifies a susceptibility locus for type 2 diabetes at 7q32 near PAX4

AIMS/HYPOTHESIS

Most genetic variants identified for type 2 diabetes have been discovered in European populations. We performed genome-wide association studies (GWAS) in a Chinese population with the aim of identifying novel variants for type 2 diabetes in Asians.

METHODS

We performed a meta-analysis of three GWAS comprising 684 patients with type 2 diabetes and 955 controls of Southern Han Chinese descent. We followed up the top signals in two independent Southern Han Chinese cohorts (totalling 10,383 cases and 6,974 controls), and performed in silico replication in multiple populations.

RESULTS

We identified CDKN2A/B and four novel type 2 diabetes association signals with p < 1 × 10(-5) from the meta-analysis. Thirteen variants within these four loci were followed up in two independent Chinese cohorts, and rs10229583 at 7q32 was found to be associated with type 2 diabetes in a combined analysis of 11,067 cases and 7,929 controls (p meta = 2.6 × 10(-8); OR [95% CI] 1.18 [1.11, 1.25]). In silico replication revealed consistent associations across multiethnic groups, including five East Asian populations (p meta = 2.3 × 10(-10)) and a population of European descent (p = 8.6 × 10(-3)). The rs10229583 risk variant was associated with elevated fasting plasma glucose, impaired beta cell function in controls, and an earlier age at diagnosis for the cases. The novel variant lies within an islet-selective cluster of open regulatory elements. There was significant heterogeneity of effect between Han Chinese and individuals of European descent, Malaysians and Indians.

CONCLUSIONS/INTERPRETATION

Our study identifies rs10229583 near PAX4 as a novel locus for type 2 diabetes in Chinese and other populations and provides new insights into the pathogenesis of type 2 diabetes.

Characterization of urinary peptide biomarkers of acute rejection in renal allografts

We previously demonstrated that 4.7 kDa and 4.4 kDa peptides are useful in diagnosing acute rejection in renal transplant recipients. The aim of this study was to characterize these polypeptides and assess their potential as biomarkers. The polypeptides were identified as human beta-Defensin-1 (4.7 kDa) and alpha-1-antichymotrypsin (4.4 kDa), by tandem mass spectrometry and ProteinChip immunoassay. The urinary abundance of both polypeptides, assessed using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS), revealed a reduction in beta-Defensin-1 while alpha-1-antichymotrypsin increased in patients with rejection (p < 0.05) compared with clinically stable transplants. The area under the curve (AUC) for the receiver operator characteristic (ROC) curve for the diagnosis of rejection for the ratio of both peptides combined was 0.912. Longitudinal analysis confirmed a reduction in beta-Defensin-1 with a reciprocal increase in alpha-1-antichymotrypsin as rejection developed. The difference in urinary beta-Defensin-1 levels quantified by radioimmunoassay was 176.8 +/- 122.3 pg/mL in stable patients compared with 83.2 +/- 52.2 pg/mL in patients with acute rejection, with an ROC AUC of 0.749 (p < 0.01). Immunohistochemistry (IHC) confirmed reduced beta-Defensin-1 expression in the renal parenchyma of patients experiencing acute rejection. In conclusion, the ratio of beta-Defensin-1 and alpha-1-antichymotrypsin excretion in the urine is a novel, potentially useful candidate biomarkers of acute rejection.

Neurologic evaluation of infant and adult rats before and after sciatic nerve blockade

BACKGROUND

Only limited data exist comparing differences in sensory function and responses to neural blockade in infant and adult rats. Therefore, the authors sought (1) to compare baseline thermal, proprioceptive, and postural responses in infant, adolescent, and adult rats; and (2) to compare the effects of sciatic nerve blockade on thermal, proprioceptive, and postural responses in infant, adolescent, and adult rats.

METHODS

Infant, adolescent, and adult rats were evaluated for proprioceptive, thermal, and mechanical nociceptive and motor function before and after sciatic blockade using a detailed neurologic examination.

RESULTS

Mechanical and thermal nociception were present in all rats, starting from age 1 day. The withdrawal reflex latency to pinch was rapid at all ages, whereas that reaction to thermal stimulus depended on both age and temperature. In contrast, the tactile placing response and hopping response were absent at birth and developed completely during the first 10 days of life. The extensor postural thrust was absent in the first 2 weeks of life and developed variably during the first 50 days of life. Sciatic blockade duration is shorter in infant rats than in adult rats receiving the same dose per kilogram. A brief halothane general anesthetic at the time of sciatic injection in infant or adult rats does not alter the duration of blockade.

CONCLUSIONS

Infant rats show increased sensitivity to noxious thermal stimuli and similar response to deep mechanical stimuli compared with adult rats. Their proprioceptive and motor responses develop during the first 2 weeks of life. When doses are scaled by body weight, block duration is shorter in infant than in adult rats.

Mutant B-RAF signaling and cyclin D1 regulate Cks1/S-phase kinase-associated protein 2-mediated degradation of p27Kip1 in human melanoma cells

Levels of cyclins and cyclin-dependent kinase (Cdk) inhibitors are tightly controlled during normal cell proliferation and are frequently dysregulated in cancerous cells. In melanoma, cyclin D1 is highly expressed and downregulation of the Cdk inhibitor, p27(Kip1), is associated with a poor prognosis. Mutant B-RAF is frequently expressed in melanoma and overrides growth factor and matrix adhesion control of cyclin D1 and p27(Kip1) levels in human melanocytes. Here, we demonstrate that p27(Kip1) expression is regulated by multiple mechanisms in melanoma cells. B-RAF regulates p27(Kip1) mRNA abundance independently of cyclin D1. Additionally, B-RAF and cyclin D1 control the levels of S-phase kinase-associated protein 2 (Skp2) that directs ubiquitin-mediated proteolysis of p27(Kip1). The cofactor for Skp2, Cdc kinase subunit 1 (Cks1) controls levels of Skp2 in melanoma cells and acts jointly with Skp2 to regulate p27(Kip1) levels. Importantly, expression of Cks1 is regulated by B-RAF and cyclin D1 at the mRNA level. Reduced Cks1 or Skp2 expression and enhanced p27(Kip1) levels inhibit melanoma cell growth. In summary, p27(Kip1) expression in melanoma is regulated by B-RAF at the mRNA level, and via B-RAF and cyclin D1 control of Cks1/Skp2-mediated proteolysis.

Proteomic analysis of hypoxia-induced responses in the syncytialization of human placental cell line BeWo

Syncytiotrophoblast formation is affected by a number of pathological conditions and suppressed syncytiotrophoblast formation due to hypoxia may play a role in the pathogenesis of preeclampsia. However, the molecular basis of hypoxia-inhibited trophoblast syncytialization is poorly understood. To determine the effect of hypoxia on trophoblast syncytialization, a proteomic analysis was performed in the human cytotrophoblast cell line BeWo using two-dimensional electrophoresis and MALDI-TOF-TOF-MS. Hypoxia induced marked inhibition of BeWo cell fusion and differentiation. The proteomic profiling was established under hypoxia in BeWo cell syncytialization. The results showed that twenty proteins were significantly up-or down-regulated under hypoxia, compared with cells under normoxia. In response to hypoxia, three antioxidants, peroxiredoxin 1, peroxiredoxin 2 and 1-Cys peroxiredoxin, were down-regulated, two proteins involved in glycolysis pathway (malate dehydrogenase and enolase) were up-regulated. The expression of two members of the annexin family (annexin A2 and annexin A5) increased. We also found a decreased expression of 14-3-3 tau protein in hypoxia treated cells. Proteins implied in protein degradation and folding were also identified. The expression of two cytoskeleton components (keratin 1 and beta-actin) was found to be down-regulated. In addition, galectin-3 was up-regulated. These proteins have been implicated in regulating cellular oxidative stress, glycolysis, signal transduction, protein folding and degradation, cell mobility and cytoskeletal structure formation. Western blot analysis revealed that the levels of peroxiredoxin 1 and 14-3-3 tau decreased, whereas the levels of annexin A5 and annexin A2 increased in BeWo cells under hypoxia. These findings provided new insights into the molecular mechanisms in mediating cellular response to hypoxia in trophoblast syncytialization.