The sbiTRS Operon Contributes to Stenobactin-Mediated Iron Utilization in Stenotrophomonas maltophilia.

Iron is an essential micronutrient for various bacterial cellular processes. Fur is a global transcriptional regulator participating in iron homeostasis. Stenotrophomonas maltophilia is a ubiquitous environmental bacterium that has emerged as an opportunistic pathogen. To elucidate the novel regulatory mechanism behind iron homeostasis in S. maltophilia, wild-type KJ and KJΔFur, a fur mutant, were subjected to transcriptome assay. A five-gene cluster, sbiBA-sbiTRS, was significantly upregulated in KJΔFur. SbiAB is an ATP type efflux pump, SbiT is an inner membrane protein, and SbiSR is a two-component regulatory system (TCS). The sbiTRS operon organization was verified by reverse transcription-PCR (RT-PCR). Localization prediction and bacterial two-hybrid studies revealed that SbiT resided in the inner membrane and had an intramembrane interaction with SbiS. In iron-replete conditions, SbiT interacted with SbiS and maintained SbiSR TCS in a resting state. In response to iron depletion stress, SbiT no longer interacted with SbiS, leading to SbiSR TCS activation. The iron source utilization assay demonstrated the contribution of SbiSR TCS to stenobactin-mediated ferric iron utilization but notto the utilization of hemin and ferric citrate. Furthermore, SmeDEF and SbiAB pumps, known stenobactin secretion outlets, were members of the SbiSR regulon. Collectively, in an iron-depleted condition, SbiSR activation is regulated by Fur at the transcriptional level and by SbiT at the posttranslational level. Activated SbiSR contributes to stenobactin-mediated ferric iron utilization by upregulating the smeDEF and sbiAB operons. SbiSR is the first TCS found to be involved in iron homeostasis in S. maltophilia. IMPORTANCE Therapeutic options for Stenotrophomonas maltophilia infections are limited because S. maltophilia is intrinsically resistant to several antibiotics. Iron is an essential element for viability, but iron overload is a lethal threat to bacteria. Therefore, disruption of iron homeostasis can be an alternative strategy to cope with S. maltophilia infection. The intricate regulatory networks involved in iron hemostasis have been reported in various pathogens; however, little is known about S. maltophilia. Herein, a novel sbiTRS operon, a member of Fur regulon, was characterized. SbiT, an inner membrane protein, negatively modulated the SbiSR two-component regulatory system by intramembrane protein-protein interaction with SbiS. In response to iron-depleted stress, SbiSR was activated via the regulation of Fur and SbiT. Activated SbiSR upregulated smeDEF and sbiAB, which contributed to stenobactin-mediated ferric iron utilization. A novel fur-sbiT-sbiSR-smeDEF/sbiAB regulatory circuit in S. maltophilia was revealed.

Predictors of Surgical Intervention for Pediatric Acute Rhinosinusitis with Periorbital Infection.

Background: Medical versus surgical management of pediatric periorbital infection secondary to acute bacterial rhinosinusitis (ABRS) can be a dilemma for clinicians. This study aimed to evaluate the prognostic factors related to the need for surgical drainage and to help direct management decisions. Methods: Children admitted for periorbital infection secondary to ABRS between 2001 and 2019 were retrospectively reviewed. Demographics, clinical presentations, laboratory data, comorbidities, and computed tomography results were collected from medical records. Results: A total of 141 pediatric patients were enrolled. Forty-two patients (29.8%) required surgical intervention. Multivariate logistic regression analysis identified that delayed initiation of intravenous antibiotics from the onset of periorbital swelling (odds ratio [OR] = 1.94; p < 0.001) and proptosis at initial presentation (OR = 6.63; p = 0.008) were significantly associated with the need for surgical intervention. A C-reactive protein value of > 55.73 mg/L and initiation of intravenous antibiotic treatment > 2 days from the onset of periorbital swelling showed the best predictive power for surgery. Conclusions: Pediatric patients with delayed initiation of intravenous antibiotic treatment and initial presentation of proptosis had worse outcomes and required surgical intervention.

Revised annotation and extended characterizations of components of the Chlamydomonas reinhardtii SUMOylation system.

Small ubiquitin-like modifier (SUMO) conjugation, or SUMOylation, is a reversible post-translational modification that is important for regulation of many cellular processes including cell division cycle in the eukaryotic kingdom. However, only a portion of the components of the Chlamydomonas SUMOylation system are known and their functions and regulation investigated. The present studies are aimed at extending discovery and characterization of new components and improving the annotation and nomenclature of all known proteins and genes involved in the system. Even though only one copy of the heterodimerized SUMO-activating enzyme, SAE1 and SAE2, was identified, the number of SUMO-conjugating enzymes (SCEs) and SUMO proteases/isopeptidase was expanded in Chlamydomonas. Using the reconstituted SUMOylation system, we showed that SCE1, SCE2, and SCE3 have SUMO-conjugating activity. In addition to SUMOylation, components required for other post-translational modifications such as NEDDylation, URMylation, and UFMylation, were confirmed to be present in Chlamydomonas. Our data also showed that besides isopeptidase activity, the SUMO protease domain of SUPPRESSOR OF MAT3 7/SENTRIN-SPECIFIC PROTEASE 1 (SMT7/SENP1) has endopeptidase activity that is capable of processing SUMO precursors. Moreover, the key cell cycle regulators of Chlamydomonas E2F1, DP1, CDKG1, CYCD2, and CYCD3 were SUMOylated in vitro, suggesting SUMOylation may be part of regulatory pathway modulating cell cycle regulators.

Biodegradation ZK50 magnesium alloy compression screws: Mechanical properties, biodegradable characteristics and implant test.

BACKGROUND: Magnesium alloy implants have lower stress load and can be absorbed gradually, but their degradation rates are too fast generally. A magnesium alloy contained 5% Zn and 0.5% Zr (ZK50) which have lower degradation rate are designed to be applied to cannulated bone screw. METHODS: An oxidation heat treatment of 380 °C for 2 h proceeds to modify the ZK50 Mg alloy (ZK50-H). The microstructure observation, degradation tests and Biocompatibility analysis are proceeded between ZK50 and ZK50-H. Finally, a mini-pig implantation test is proceeded to provide a reference of implant application for future pre-clinical evaluation. RESULTS: The heat treatment can improve the mechanical properties. A passive ceramic layer formed after simulated body fluid (SBF) solution immersion can restrict the degradation effectively. The cytotoxicity test shows the initial biosafety of ZK50 Mg alloy. A mini-pig implantation test of bone screw has proceeded to confirm the advanced biocompatibility. The ZK50-H screws can maintain enough support at least 8 weeks which the fracture of bone can get curing. The excellent osteoinduction of ZK50-H has a positive effect to growth of new bones and help the mini-pig regain heal faster in 12 weeks. CONCLUSION: This study shows ZK50-H Mg alloy screw is a feasible degradation implant and can be carried out the next-step clinical experiments.

SUMO Protease SMT7 Modulates Ribosomal Protein L30 and Regulates Cell-Size Checkpoint Function.

Proliferating cells actively coordinate growth and cell division to ensure cell-size homeostasis; however, the underlying mechanism through which size is controlled is poorly understood. Defect in a SUMO protease protein, suppressor of mat3 7 (SMT7), has been shown to reduce cell division number and increase cell size of the small-size mutant mating type locus 3-4 (mat3-4), which contains a defective retinoblastoma tumor suppressor-related protein of Chlamydomonas (Chlamydomonas reinhardtii). Here we describe development of an in vitro SUMOylation system using Chlamydomonas components and use it to provide evidence that SMT7 is a bona fide SUMO protease. We further demonstrate that the SUMO protease activity is required for supernumerous mitotic divisions of the mat3-4 cells. In addition, we identified RIBOSOMAL PROTEIN L30 (RPL30) as a prime SMT7 target and demonstrated that its SUMOylation is an important modulator of cell division in mat3-4 cells. Loss of SMT7 caused elevated SUMOylated RPL30 levels. Importantly, overexpression of the translational fusion version of RPL30-SUMO4, which mimics elevation of the SUMOylated RPL30 protein in mat3-4, caused a decrease in mitotic division and recapitulated the size-increasing phenotype of the smt7-1 mat3-4 cells. In summary, our study reveals a novel mechanism through which a SUMO protease regulates cell division in the mat3-4 mutant of Chlamydomonas and provides yet another important example of the role that protein SUMOylation can play in regulating key cellular processes, including cell division.

An Assessment of Factors Related to Ocean Literacy Based on Gender-Invariance Measurement.

This study sought to gain a more comprehensive understanding of how the factors of parental education level and student attitude toward the ocean influence the ocean literacy of students in Taiwan after establishing measurement invariance across genders. The analyzed data were collected from self-reported questionnaires filled out by students aged 16-18 years old. The students' ocean literacy was used as the outcome variable, while parental education level and student attitude toward the ocean were employed as the independent variables. The effects of parental education level and student attitude toward the ocean on ocean literacy were estimated with a multi-group structural equation model. Of the final total of 945 valid respondents in this study, 58.1% were male and 41.9% were female. The results from the multiple-group analysis supported measurement invariance across the genders. After establishing gender invariance, it was further found that higher degrees of parental education level and student attitude toward the ocean were positively related to ocean literacy. A considerable contribution was detected between parental education level and ocean literacy that was indirectly related through student attitude toward the ocean in the female student.

Preparation of fibril nuclei of beta-amyloid peptides in reverse micelles.

We report the preparation of protofibrils from oligomeric Aß40 aggregates, which have been incubated under spatially constrained conditions. The molecular structure of the resultant protofibrils is highly homogeneous, suggesting that the phenomenon of structural polymorphism commonly observed in Aß40 fibrils may be largely due to multiple nucleation events.

Long-term administration of olanzapine induces adiposity and increases hepatic fatty acid desaturation protein in female C57BL/6J mice.

OBJECTIVES: Weight gain and metabolic disturbances such as dyslipidemia, are frequent side effects of second-generation antipsychotics, including olanzapine. This study examined the metabolic effects of chronic olanzapine exposure. In addition, we investigated the hepatic fatty acid effects of olanzapine in female C57BL/6J mice fed a normal diet. MATERIALS AND METHODS: Female C57BL/6J mice orally received olanzapine or normal saline for 7 weeks. The effects of long-term olanzapine exposure on body weight changes, food efficiency, blood glucose, triglyceride (TG), insulin, and leptin levels were observed. Hepatic TG and abdominal fat mass were investigated, and fat cell morphology was analyzed through histopathological methods. The levels of protein markers of fatty acid regulation in the liver, namely fatty acid synthase (FAS) and stearoyl-CoA desaturase-1 (SCD-1), were measured. RESULTS: Olanzapine treatment increased the food intake of the mice as well as their body weight. Biochemical analyses showed that olanzapine increased blood TG, insulin, leptin, and hepatic TG. The olanzapine group exhibited increased abdominal fat mass and fat cell enlargement in abdominal fat tissue. Western blotting of the mouse liver revealed significantly higher (1.6-fold) levels of SCD-1 in the olanzapine group relative to the control group; by contrast, FAS levels in the two groups did not differ significantly. CONCLUSION: Enhanced lipogenesis triggered by increased hepatic SCD-1 activity might be a probable peripheral mechanism of olanzapine-induced dyslipidemia. Some adverse metabolic effects of olanzapine may be related to the disturbance of lipid homeostasis in the liver.

Silencing bcl-2 expression in epithelial cancer cells using "smart" particles.

Short interfering RNA (siRNA) targeted against anti-apoptotic Bcl-2 protein proved to knockdown its expression and trigger cancer cell death. We used degradable, pH-sensitive, comb-like [P(EAA-co-BMA)-b-PNASI-g-P(HMA-co-TMAEMA)] polymer to condense anti-Bcl-2 siRNA into "smart" particles, which proved to shuttle their cargo past the endosomal membrane and into the cytoplasm of HeLa and UM-SCC-17B cancer cells. HeLa and UM-SCC-17B cancer cells were treated with anti-Bcl-2 particles followed by quantifying Bcl-2 mRNA and protein levels using qRT-PCR and western blotting, respectively. "Smart" anti-Bcl-2 particles selectively suppress Bcl-2 mRNA and protein levels in HeLa cells by 50%-60% and 79%-81%, respectively. Similarly, "smart" anti-Bcl-2 particles inhibited Bcl-2 mRNA levels by 30%, 40%, and 20% upon incubation with UM-SCC-17B cancer cells for 48, 72, and 96 h, respectively. Bcl-2 protein expression in UM-SCC-17B cancer cells was inhibited by 30% after treatment for 72 h. Results show that pH-sensitive comb-like polymer complex anti-Bcl-2 siRNA forming "smart" nanoparticles that deliver their cargo into the cytoplasm of HeLa and UM-SCC-17B cancer cells causing Bcl-2 knockdown at the mRNA and protein levels.

Fas/Fas ligand mediates keratinocyte death in sunitinib-induced hand-foot skin reaction.

Sunitinib, a multitargeted receptor Y kinase inhibitor (TKI) used for the treatment of renal cell carcinoma and gastrointestinal stromal tumor (GIST), is notorious for cutaneous adverse effects, such as hand-foot skin reaction (HFSR). To explore the underlying mechanism of HFSR, we enrolled 53 sunitinib-treated GIST patients, including 23 HFSR cases, and 30 tolerant controls. Among the 29 biomarkers examined, soluble FasL (sFasL) showed significant increase in the plasma, blister fluids, and skin lesions of HFSR patients. The plasma levels of sFasL were significantly correlated with those of sunitinib in HFSR patients. In addition to FasL, augmented expression of Fas and active caspase 3 was also detected in the epidermis of HFSR patients. The increased FasL caused keratinocyte death, as the use of anti-FasL antibody specifically blocked cell apoptosis. Oral administration of sunitinib to mice increased skin susceptibility to mechanical injuries in a dose/time-dependent manner. The administration of sunitinib (40 mg kg(-1) per day) for 4 weeks to mice caused the maximally affected skin area with an erosion-to-ulceration response to tape-stripping. The skin biopsies of mice administered sunitinib exhibited increased expression of Fas and FasL in the apoptotic keratinocytes in the epidermis. Our data revealed that Fas/FasL interaction mediates keratinocyte death in sunitinib-induced HFSR.

Synergistic combination of small molecule inhibitor and RNA interference against antiapoptotic Bcl-2 protein in head and neck cancer cells.

B-cell lymphoma 2 (Bcl-2) is an antiapoptotic protein that is overexpressed in head and neck squamous cell carcinomas, which has been implicated in development of radio- and chemoresistance. Small molecule inhibitors such as AT-101 (a BH3-mimetic drug) have been developed to inhibit the antiapoptotic activity of Bcl-2 proteins, which proved effective in restoring radio- and chemo-sensitivity in head and neck cancer cells. However, high doses of AT-101 are associated with gastrointestinal, hepatic, and fertility side effects, which prompted the search for other Bcl-2 inhibitors. Short interfering RNA (siRNA) proved to inhibit antiapoptotic Bcl-2 protein expression and trigger cancer cell death. However, transforming siRNA molecules into a viable therapy remains a challenge due to the lack of efficient and biocompatible carriers. We report the development of degradable star-shaped polymers that proved to condense anti-Bcl-2 siRNA into "smart" pH-sensitive and membrane-destabilizing particles that shuttle their cargo past the endosomal membrane and into the cytoplasm of head and neck cancer cells. Results show that "smart" anti-Bcl-2 particles reduced the mRNA and protein levels of antiapoptotic Bcl-2 protein in UM-SCC-17B cancer cells by 50-60% and 65-75%, respectively. Results also show that combining "smart" anti-Bcl-2 particles with the IC25 of AT-101 (inhibitory concentration responsible for killing 25% of the cells) synergistically inhibits cancer cell proliferation and increases cell apoptosis, which reduce the survival of UM-SCC-17B cancer cells compared to treatment with AT-101 alone. Results indicate the therapeutic benefit of combining siRNA-mediated knockdown of antiapoptotic Bcl-2 protein expression with low doses of AT-101 for inhibiting the growth of head and neck cancer cells.

Visualizing the attack of RNase enzymes on dendriplexes and naked RNA using atomic force microscopy.

Cationic polymers such as poly(amidoamine), PAMAM, dendrimers have been used to electrostatically complex siRNA molecules forming dendriplexes for enhancing the cytoplasmic delivery of the encapsulated cargo. However, excess PAMAM dendrimers is typically used to protect the loaded siRNA against enzymatic attack, which results in systemic toxicity that hinders the in vivo use of these particles. In this paper, we evaluate the ability of G4 (flexible) and G5 (rigid) dendrimers to complex model siRNA molecules at low +/- ratio of 2/1 upon incubation for 20 minutes and 24 hours. We examine the ability of the formed G4 and G5 dendriplexes to shield the loaded siRNA molecules and protect them from degradation by RNase V1 enzymes using atomic force microscopy (AFM). Results show that G4 and G5 dendrimers form similar hexagonal complexes upon incubation with siRNA molecules for 20 minutes with average full width of 43±19.3 nm and 62±8.3 at half the maximum height, respectively. AFM images show that these G4 and G5 dendriplexes were attacked by RNase V1 enzyme leading to degradation of the exposed RNA molecules that increased with the increase in incubation time. In comparison, incubating G4 and G5 dendrimers with siRNA for 24 hours led to the formation of large particles with average full width of 263±60 nm and 48.3±2.5 nm at half the maximum height, respectively. Both G4 and G5 dendriplexes had a dense central core that proved to shield the loaded RNA molecules from enzymatic attack for up to 60 minutes. These results show the feasibility of formulating G4 and G5 dendriplexes at a low N/P (+/-) ratio that can resist degradation by RNase enzymes, which reduces the risk of inducing non-specific toxicity when used in vivo.

Linear plasmids mobilize linear but not circular chromosomes in Streptomyces: support for the 'end first' model of conjugal transfer.

Gram-positive bacteria of the genus Streptomyces possess linear chromosomes and linear plasmids capped by terminal proteins covalently bound to the 5' ends of the DNA. The linearity of Streptomyces chromosomes raises the question of how they are transferred during conjugation, particularly when the mobilizing plasmids are also linear. The classical rolling circle replication model for transfer of circular plasmids and chromosomes from an internal origin cannot be applied to this situation. Instead it has been proposed that linear Streptomyces plasmids mobilize themselves and the linear chromosomes from their telomeres using terminal-protein-primed DNA synthesis. In support of this 'end first' model, we found that artificially circularized Streptomyces chromosomes could not be mobilized by linear plasmids (SLP2 and SCP1), while linear chromosomes could. In comparison, a circular plasmid (pIJ303) could mobilize both circular and linear chromosomes at the same efficiencies. Interestingly, artificially circularized SLP2 exhibited partial self-transfer capability, indicating that, being a composite replicon, it may have acquired the additional internal origin of transfer from an ancestral circular plasmid during evolution.

Site-directed mutations of thermostable direct hemolysin from Grimontia hollisae alter its arrhenius effect and biophysical properties.

Recombinant thermostable direct hemolysin from Grimontia hollisae (Gh-rTDH) exhibits paradoxical Arrhenius effect, where the hemolytic activity is inactivated by heating at 60 °C but is reactivated by additional heating above 80 °C. This study investigated individual or collective mutational effect of Tyr53, Thr59, and Ser63 positions of Gh-rTDH on hemolytic activity, Arrhenius effect, and biophysical properties. In contrast to the Gh-rTDH wild-type (Gh-rTDH(WT)) protein, a 2-fold decrease of hemolytic activity and alteration of Arrhenius effect could be detected from the Gh-rTDH(Y53H/T59I) and Gh-rTDH(T59I/S63T) double-mutants and the Gh-rTDH(Y53H/T59I/S63T) triple-mutant. Differential scanning calorimetry results showed that the Arrhenius effect-loss and -retaining mutants consistently exhibited higher and lower endothermic transition temperatures, respectively, than that of the Gh-rTDH(WT). Circular dichroism measurements of Gh-rTDH(WT) and Gh-rTDH(mut) showed a conspicuous change from a ß-sheet to α-helix structure around the endothermic transition temperature. Consistent with the observation is the conformational change of the proteins from native globular form into fibrillar form, as determined by Congo red experiments and transmission electron microscopy.

The health benefits following regular ongoing exercise lifestyle in independent community-dwelling older Taiwanese adults.

AIM: To examine the effect of regular ongoing exercise lifestyle on mental and physical health in a group of independent community-dwelling Taiwanese older adults over a 2-year period. METHODS: 197 older adults (mean age 72.5 years; 106 men and 91 women) who were independent in walking, instrumental and basic activities of daily living completed the baseline and a 2-year follow-up assessment. Older adults regularly performing exercises during the 2-year study period were grouped into regular exercise group; otherwise in the irregular exercise group. Baseline and follow-up assessments included a face-to-face interview and a battery of performance tests. RESULTS: The regular exercise group showed significantly less depression (P = 0.03) and tended to regress less on the performance tests (P = 0.025-0.410) across 2 years compared to the irregular exercise group. CONCLUSION: Regular exercise is important for maintaining or even improving mental and functional health, even for independent community-dwelling older adults.

Quantitative evaluation of the effect of poly(amidoamine) dendrimers on the porosity of epithelial monolayers.

Poly(amidoamine) (PAMAM) dendrimers are a family of water-soluble polymers with a characteristic tree-like branching architecture and a large number of surface groups, which have been used to immobilize a variety of therapeutic molecules for targeted drug delivery. Earlier studies showed that small cationic PAMAM-NH2 and selected anionic PAMAM-COOH dendrimers permeate across in vitro models of the small intestinal epithelium by paracellular and transcellular transport mechanisms. The focus of this research is to mathematically calculate the effect of cationic, anionic, and neutral PAMAM dendrimers on the porosity of epithelial tight junctions as a function of dendrimers concentration, incubation time, generation number, and charge density. Results show that the increase in the concentration, incubation time and generation number of cationic G0-G2 PAMAM-NH2 and anionic G2.5 and G3.5 PAMAM-COOH dendrimers caused a corresponding increase in the porosity of Caco-2 cell monolayers. Neutral G2-G4 PAMAM-OH dendrimers had no effect on the porosity of intestinal cells. These results provide quantitative evidence that the observed increase in permeability of PAMAM dendrimers across Caco-2 cell monolayers is due to their effect on the organization of the tight junctions and the associated increase in membrane porosity. Furthermore, these results emphasize the potential of cationic PAMAM-NH2 and anionic PAMAM-COOH dendrimers to function as carriers for controlled oral drug delivery.

Degradable, pH-sensitive, membrane-destabilizing, comb-like polymers for intracellular delivery of nucleic acids.

This report describes the design and synthesis of a new series of degradable, pH-sensitive, membrane-destabilizing, comb-like polymers that can enhance the intracellular delivery of therapeutic nucleic acids. These comb-like polymers are based on a diblock polymer backbone where the first block is a copolymer of pH-sensitive ethyl acrylic acid (EAA) monomers and hydrophobic butyl methacrylate (BMA) or hexyl methacrylate monomers. The second block is a homopolymer of N-acryloxy succinimide (NASI) or ss-benzyl l-aspartate N-carboxy-anhydride (BLA-NCA) monomers, which are functionalized to allow controlled grafting of hydrophobic HMA and cationic trimethyl aminoethyl methacrylate (TMAEMA) copolymers via acid-labile hydrazone linkages. These comb-like polymers displayed high hemolytic activity in acidic solutions, which increased with the increase in polymer concentration. All comb-like polymers degraded into small fragments upon incubation in an acidic solution (pH 5.8) due to hydrolysis of the hydrazone linkages connecting the hydrophobic/cationic grafts to the polymer backbone. Comb-like polymers successfully complexed anti-GAPDH siRNA molecules into serum- and nuclease-stable particles, which successfully silenced GAPDH expression at both the mRNA and protein levels. These results collectively indicate the potential of these new comb-like polymers to serve as vehicles for effective intracellular delivery of therapeutic nucleic acids.

The effect of chitosan and PVDF substrates on the behavior of embryonic rat cerebral cortical stem cells.

In this study, the behavior of neural stem cells from embryonic rat cerebral cortex were compared on the chitosan and poly(vinylidene fluoride) (PVDF) substrates at single-cell and neurosphere level. It was found that chitosan and PVDF substrates inhibited the proliferation and differentiation of single neural stem cells. It seemed that single-cell cultures on both substrates show cells remained dormant. However, neurospheres could exhibit different or similar behavior on these two substrates, which is dependent on the presence or absence of serum. More cells migrated outside from the neurospheres and longer processes extended from differentiated cells on chitosan than on PVDF when neurospheres were cultured in the serum-free medium. On the contrary, when serum was added to the culture system, chitosan and PVDF could induce the neurosphere-forming cells into an extensive cellular substratum of protoplasmic cells upon which process-bearing cells spread. In addition, based on the immunocytochemical analysis, the percentages of differentiated cell phenotypes of neurospheres cultured on chitosan and PVDF substrates became similar in the presence of serum. Therefore, it is reasonable to suggest that biomaterials may stimulate or inhibit the proliferation and differentiation of neural stem cells according to the complex environmental conditions. The information presented here should be useful for the development of biomaterials to regulate the preservation, proliferation, and differentiation of neural stem cells.

HLA-B*5801 allele as a genetic marker for severe cutaneous adverse reactions caused by allopurinol.

Allopurinol, a commonly prescribed medication for gout and hyperuricemia, is a frequent cause of severe cutaneous adverse reactions (SCAR), which include the drug hypersensitivity syndrome, Stevens-Johnson syndrome, and toxic epidermal necrolysis. The adverse events are unpredictable and carry significant morbidity and mortality. To identify genetic markers for allopurinol-SCAR, we carried out a case-control association study. We enrolled 51 patients with allopurinol-SCAR and 228 control individuals (135 allopurinol-tolerant subjects and 93 healthy subjects from the general population), and genotyped for 823 SNPs in genes related to drug metabolism and immune response. The initial screen revealed strong association between allopurinol-SCAR and SNPs in the MHC region, including BAT3 (encoding HLA-B associated transcript 3), MSH5 (mutS homolog 5), and MICB (MHC class I polypeptide-related sequence B) (P < 10(-7)). We then determined the alleles of HLA loci A, B, C, and DRB1. The HLA-B*5801 allele was present in all (100%) 51 patients with allopurinol-SCAR, but only in 20 (15%) of 135 tolerant patients [odds ratio 580.3 (95% confidence interval, 34.4-9780.9); corrected P value = 4.7 x 10(-24)] and in 19 (20%) of 93 of healthy subjects [393.51 (23.23-6665.26); corrected P value = 8.1 x 10(-18)]. HLA alleles A*3303, Cw*0302, and DRB1*0301 were in linkage disequilibrium and formed an extended haplotype with HLA-B*5801. Our results indicated that allopurinol-SCAR is strongly associated with a genetic predisposition in Han Chinese. In particular, HLA-B*5801 allele is an important genetic risk factor for this life-threatening condition.