HTS driven by fluorescence lifetime detection of FRET identifies activators and inhibitors of cardiac myosin

Small molecules that bind to allosteric sites on target proteins to alter protein function are highly sought in drug discovery. High-throughput screening (HTS) assays are needed to facilitate the direct discovery of allosterically active compounds. We have developed technology for high-throughput time-resolved fluorescence lifetime detection of fluorescence resonance energy transfer (FRET), which enables the detection of allosteric modulators by monitoring changes in protein structure. We tested this approach at the industrial scale by adapting an allosteric FRET sensor of cardiac myosin to high-throughput screening (HTS), based on technology provided by Photonic Pharma and the University of Minnesota, and then used the sensor to screen 1.6 million compounds in the HTS facility at Bristol Myers Squibb. The results identified allosteric activators and inhibitors of cardiac myosin that do not compete with ATP binding, demonstrating high potential for FLT-based drug discovery.

597. Are We Dosing Correctly? Population Pharmacokinetic Modeling of Cefepime, Piperacillin-Tazobactam, and Meropenem in Individuals with Cystic Fibrosis

Background

Patients with cystic fibrosis (CF) experience recurrent bacterial pulmonary exacerbations. The management of these infections becomes increasingly complex due to decreased antimicrobial susceptibility and inadequate pharmacokinetic/pharmacodynamic (PK/PD) characterization of the most commonly used antimicrobial agents in this population.

Methods

One hundred fifty-five pediatric and adult participants receiving cefepime (n=82), meropenem (n=42), or piperacillin-tazobactam (n=31) were enrolled. Opportunistic blood samples were obtained during hospitalization. Population PK (PopPK) analysis was conducted using nonlinear mixed effects modeling in NONMEM, and clinical and demographic characteristics were evaluated as potential covariates. Monte Carlo simulations evaluated the probability of PK/PD target attainment (PTA) for different dosing regimens. Multiple targets, defined as percentage of a 24-h time period that the free drug concentration exceeds the MIC (fT > MIC), were selected based on prior studies of beta-lactam antibiotics.

Results

Preliminary PopPK modeling results show that lean body weight, creatinine clearance, daily dose, mode of administration (standard vs. extended infusion), and age affect PK parameters, with varying effects by drug. As anticipated, extended or continuous infusions resulted in higher PTA (Table 1). In the cefepime group, the 3-h infusion regimen achieved higher PTAs than the 0.5-h regimen across all age groups (Figure 1, Figure 2). Estimated breakpoints (in which ≥ 90% of patients are expected to achieve a PK/PD target) were 2-4 fold higher in pediatric participants receiving a 3-h infusion vs. 0.5-h infusion, based on age and target fT > MIC (Table 1). In the meropenem group, increased creatinine clearance led to reduced PTA, and in the piperacillin-tazobactam group, total daily dose and interval were the principal drivers of PTA. Table 1:Breakpoints (mg/L, highest minimum inhibitory concentration (MIC) with ≥ 90% PK target attainment) for different infusion durations, based on Monte Carlo simulations.Figure 1:Comparison of PTA between the two durations of infusion for 50 mg/kg (3 to 11 years) or 2 g (12 years and above) cefepime q8h at the target of 65% fT> MIC.Figure 2:Comparison of PTA between two durations of infusion for 50 mg/kg (3 to 11 years) or 2 g (12 years and above) cefepime q8h at the target of 100% fT> MIC.

Conclusion

To our knowledge, this is the largest PopPK study to date of these antimicrobials in individuals with CF. Clinicians should incorporate local antibiograms with these PopPK models to determine optimal dosing in patients with CF, since standard dosing regimens may fail to achieve specific PK/PD targets. This population may also benefit from beta-lactam therapeutic drug monitoring.

Disclosures

C. Buddy Creech, MD, MPH, Altimmune: Advisor/Consultant|Astellas: Advisor/Consultant|Merck: Grant/Research Support|Premier: Advisor/Consultant.

SELNET clinical practice guidelines for bone sarcoma

Bone sarcoma are infrequent diseases, representing < 0.2% of all adult neoplasms. A multidisciplinary management within reference centers for sarcoma, with discussion of the diagnostic and therapeutic strategies within an expert multidisciplinary tumour board, is essential for these patients, given its heterogeneity and low frequency. This approach leads to an improvement in patient's outcome, as demonstrated in several studies. The Sarcoma European Latin-American Network (SELNET), aims to improve clinical outcome in sarcoma care, with a special focus in Latin-American countries. These Clinical Practice Guidelines (CPG) have been developed and agreed by a multidisciplinary expert group (including medical and radiation oncologist, surgical oncologist, orthopaedic surgeons, radiologist, pathologist, molecular biologist and representatives of patients advocacy groups) of the SELNET consortium, and are conceived to provide the standard approach to diagnosis, treatment and follow-up of bone sarcoma patients in the Latin-American context.

Taxane-induced Attenuation of the CXCR2/BCL-2 Axis Sensitizes Prostate Cancer to Platinum-based Treatment

BACKGROUND

Taxanes are the most active chemotherapy agents in metastatic castration-resistant prostate cancer (mCRPC) patients; yet, resistance occurs almost invariably, representing an important clinical challenge. Taxane-platinum combinations have shown clinical benefit in a subset of patients, but the mechanistic basis and biomarkers remain elusive.

OBJECTIVE

To identify mechanisms and response indicators for the antitumor efficacy of taxane-platinum combinations in mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

Transcriptomic data from a publicly available mCRPC dataset of taxane-exposed and taxane-naïve patients were analyzed to identify response indicators and emerging vulnerabilities. Functional and preclinical validation was performed in taxane-resistant mCRPC cell lines and genetically engineered mouse models (GEMMs).

INTERVENTION

Metastatic CRPC cells were treated with docetaxel, cisplatin, carboplatin, the CXCR2 antagonist SB265610, and the BCL-2 inhibitor venetoclax. Gain and loss of function in culture of CXCR2 and BCL-2 were achieved by overexpression or siRNA silencing. Preclinical assays in GEMM mice tested the antitumor efficacy of taxane-platinum combinations.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Proliferation, apoptosis, and colony assays measured drug activity in vitro. Preclinical endpoints in mice included growth, survival, and histopathology. Changes in CXCR2, BCL-2, and chemokines were analyzed by reverse transcriptase quantitative polymerase chain reaction and Western blot. Human expression data were analyzed using Gene Set Enrichment Analysis, hierarchical clustering, and correlation studies. GraphPad Prism software and R-studio were used for statistical and data analyses.

RESULTS AND LIMITATIONS

Transcriptomic data from taxane-exposed human mCRPC tumors correlate with a marked negative enrichment of apoptosis and inflammatory response pathways accompanied by a marked downregulation of CXCR2 and BCL-2. Mechanistically, we show that docetaxel inhibits CXCR2 and that BCL-2 downregulation occurs as a downstream effect. Further, we demonstrated in experimental models that the sensitivity to cisplatin is dependent on CXCR2 and BCL-2, and that targeting them sensitizes prostate cancer (PC) cells to cisplatin. In vivo taxane-platinum combinations are highly synergistic, and previous exposure to taxanes sensitizes mCRPC tumors to second-line cisplatin treatment.

CONCLUSIONS

The hitherto unappreciated attenuation of the CXCR2/BCL-2 axis in taxane-treated mCRPC patients is an acquired vulnerability with potential predictive activity for platinum-based treatments.

PATIENT SUMMARY

A subset of patients with aggressive and therapy-resistant prostate cancer benefits from taxane-platinum combination chemotherapy; however, we lack the mechanistic understanding of how that synergistic effect occurs. Here, using patient data and preclinical models, we found that taxanes reduce cancer cell escape mechanisms to chemotherapy-induced cell death, hence making these cells more vulnerable to additional platinum treatment.

MYT1 role in the microtia-craniofacial microsomia spectrum

Background

Craniofacial microsomia (CFM), also known as the oculo‐auriculo‐vertebral spectrum, comprises a variable phenotype with the most common features including microtia and mandibular hypoplasia on one or both sides, in addition to lateral oral clefts, epibulbar dermoids, cardiac, vertebral, and renal abnormalities. The etiology of CFM is largely unknown. The MYT1 gene has been reported as a candidate based in mutations found in three unrelated individuals. Additional patients with mutations in this gene are required to establish its causality. We present two individuals with CFM that have rare variants in MYT1 contributing to better understand the genotype and phenotype associated with mutations in this gene.

Methods/Results

We conducted genetic analysis using whole‐exome and ‐genome sequencing in 128 trios with CFM. Two novel MYT1 mutations were identified in two participants. Sanger sequencing was used to confirm these mutations.

Conclusion

We identified two additional individuals with CFM who carry rare variants in MYT1, further supporting the presumptive role of this gene in the CFM spectrum.

Association of neuroendocrine (NE) mRNA expression profiling in hormone-sensitive tumors samples with adverse clinical outcome in castration-resistant prostate cancer (CRPC) patients

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Background: NE dedifferentiation is associated to clinical aggressiveness and resistance to androgen receptor inhibition in prostate cancer. We investigated impact of a NE expression signature in the clinical outcome of mCRPC patients treated with taxanes. Methods: This is a multicenter retrospective study. A customized panel of 45 NE-related gene signature was tested in total RNA from formalin-fixed paraffin-embedded hormone-sensitive tumor samples, by the nCounter platform (Nanostring Technologies). Patients were grouped according to their molecular profile by unsupervised clustering. Expression levels were correlated with taxanes response and clinical outcome. Independent association with survival was evaluated by multivariate Cox modeling. Results: Eighty seven patients were included in the study, 79 were treated with docetaxel and 8 with cabazitaxel. Median age was 64.8 (44-88.3) years and median follow-up was 20.7 (1.17-74.4) months. High expression of the NE signature was associated with a shorter time of CRPC development (N=60, median 12.8 vs 21.6, HR 2.4, 95%CI 1.3-4.3, P=0.003) and shorter OS from CRPC diagnosis (median 24.1 vs 41.33, HR 2.3, 95%CI 1.4-3.8, P=0.001). Moreover, according to the outcome to taxanes, high NE signature correlated with lower PSA-PFS (median 6.6 vs 10.1 mo P=0.047, HR 1.6, 95%CI 1-2.7, P=0.05) and OS (median 19 vs 22 mo, HR 1.8, 95%CI 1.1-2.8, P=0.014), and it was independently associated to a lower OS (HR 1.9, 95%CI 1.1-3.2, P=0.016). Conclusions: NE-related gene expression in hormone-sensitive tumor samples is associated with adverse clinical outcome and lower taxane benefit in metastatic CRPC patients. Thus, molecular characterization of primary tumors may be useful to guide treatment strategies in metastatic prostate cancer.

Disparities in Use of Subspecialty Concussion Care Based on Ethnicity

Concussion is common and subspecialty care can be essential to ensure recovery. However, barriers may exist to accessing care. This study aimed to assess disparities in subspecialty concussion care related to ethnicity, limited English proficiency (LEP), and insurance status. We utilized logistic regression to analyze 2010-2015 administrative data from four Sports Medicine clinics, comparing odds of being seen for concussion to odds of being seen for fracture by ethnicity, insurance type, and interpreter usage, controlling for demographic factors. ICD-9 codes were used to identify concussion and fracture. Our final sample contained 25,294 subjects: 5621 with concussion and 19,673 with fracture. In bivariate analysis, youth seen for concussion had 83% lower odds of being Hispanic compared with youth seen for fracture (95%CI: 75-92%). Due to interactions between ethnicity and interpreter use, we utilized a stratified multivariate model as our final model. Youth with concussion had 1.8× greater odds of having private insurance compared with youth with fracture (Hispanic OR 1.8, 95% CI 1.5-2.3; Non-Hispanic OR 1.8, 95% CI 1.7-2.0). Youth with concussion also had greater odds of not using an interpreter, though the strength of this association was weaker for Hispanic youth compared with non-Hispanic youth (Hispanic OR 1.68, 95% CI 1.30-2.17; Non-Hispanic OR 4.36, 95% CI 3.00-6.35). Age and sex were included as covariates. In conclusion, our analysis suggests disparities in subspecialty concussion care for Hispanic youth, as well as for individuals with LEP and non-private insurance. Further research should explore means for improving access to concussion care for all youth.

In vitro characterization and clinical use of platelet-rich plasma-derived Endoret-Gel as an autologous treatment for atrophic scars

BACKGROUND

Normal healing process becomes severely dysregulated in pathophysiological conditions such as inflammation, infection or underlaying diseases. These scenarios hamper the standard healing pattern and dermal fibrotic tissue develops.

OBJECTIVE

In the present study a novel three-dimensional formulation (Endoret-Gel) based on plasma rich in growth factors technology (Endoret-PRGF) has been assessed for atrophic scar management.

MATERIALS AND METHODS

Microstructure analysis, growth factor content, and projection capacity of both formulations (Endoret-Gel and Endoret-PRGF) was assessed. Additionally, a clinical evaluation of Endoret-Gel treatment was also performed in a case of an extense atrophic scar.

RESULTS

Endoret-Gel presented high molecular weight plasmatic proteins that formed solid thermal aggregates enclosed by a stable fibrin network. This formulation has a higher cutaneous projection capacity compared with Endoret-PRGF. Both formulations presented a high load of bioactive proteins such as EGF, PDGF-AB, and IGF-I being higher in liquid Endoret-PRGF. Clinical results evidenced that infiltrations of Endoret-Gel derived in an early volumetric disposal that was maintained for several months. The treatment provided and immediate soft tissue augmentation and scar amelioration effect that was translated into a noticeable clinical improvement of the injury. No side effects or adverse events were reported during ten-month follow-up period.

CONCLUSION

These preliminary findings suggest that Endoret-Gel may act not only as a temporary volumizer but also as soft tissue stimulator that might be used as a monotherapy for scar management.

ARV7/AR ratio and neutrophil-to-lymphocyte ratio (NLR) as predictors of docetaxel benefit in metastatic castration-resistant prostate cancer patients (mCRPC)

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Background: The constitutively active androgen receptor (AR) variant 7 (ARV7) has been associated to AR inhibitors resistance, but its role in taxane-benefit has not been stablished. Moreover, the neutrophil-to-lymphocyte ratio (NLR) has been associated with poor outcome in prostate cancer.The PBMC population may contain circulating tumor cells (CTCs) but is mainly constituted by lymphocytes and monocytes, that also express the AR. Here we studied the expression of ARV7 and AR in peripheral blood mononuclear cells (PBMC) and its correlation with NLR and clinical outcome in mCRPC treated with docetaxel. Methods: ARV7 and AR mRNAs were tested by quantitative reverse-transcription PCR. Baseline neutrophil and lymphocyte values and PBMC samples were prospectively collected before treatment initiation. Patients were stratified according to NLR ratio (low NLR: ≤3; high NLR:>3) and to ARV7/ARFL ratio expression (Maxstat Cutoff 1.99). Correlation between NLR and PSA progression-free (PSA-PFS) and overall survival (OS), were measured from the start of docetaxel treatment and calculated by log rank test. Results: Fifty patients were included:25 (50%) had low NLR. Thirty-eight patients (76%) expressed high ARV7/ARFL. No significant correlation between NLR with ARV7, AR and ARV7/AR was observed. High ARV7/ARF ratio correlated to a better PSA-PFS (median PSA-PFS 7.47; HR 0.38, 95%CI 0.17-0.85; P=0.0179) , but not OS. High NLR was associated to a lower OS [Median OS was 9.2 months versus 30.17 months in those with low NLR (HR 2.19, 95% CI 1.17-4.09, p= 0.01)]. When both parameters were combined, high NLR and low ARV7/ARFL ratio were associated to a worse PSA-PFS in comparison with low NLR and high ARV7/ARFL ratiogroup(median PSA-PFS: 4.9 vs. 7.5; p=0.008 and HR 5.08, 95% CI 1.33-19.41, p= 0.08) and OS (median OS: 7.4 vs. 30.5; p=0.001 and HR 22.79, 95% CI 4.29-121.17, p= 0.00). Conclusions: The combination of low ARV7/ARFL high NLR and ratio evaluated in PBMC prior to docetaxel treatment has a predictive impact on response and survival in mCRPC patients.

Participants’ Perspectives of a Culturally Competent Diabetes Education for Hispanic/Latinos

Background: ¡Si, Yo Puedo Controlar Mi Diabetes! (Sí, Yo Puedo) is a culturally appropriate diabetes self-management education program targeting underserved Hispanic/Latinos. Purpose: The purpose of this article is to report on our post-test focus group observations that elaborate upon quantitative evaluation results that are published elsewhere. Methods: Following a seven-week intervention, we conducted seven focus groups to capture participants’ perspectives about managing their diabetes before and after participating in classes. These sessions were held during a one-month post-intervention (reunion) session. Results: Participants were mostly female (77%; N=34) with a mean age of 58.8 years. Perceived improvements in eating habits, blood glucose testing, and physical activity were among the positive outcomes of attending the program. Barriers to diabetes self-management included struggles changing lifestyle habits, accepting disease diagnosis, and financial issues. Despite these concerns, participants found Sí, Yo Puedo to be beneficial, especially with psychosocial support. “Not feeling alone” was a prevailing sentiment expressed by participants. Conclusions: Overall, participants indicated the program was relevant to their needs. This study suggests that Sí, Yo Puedo is an effective program to reach Hispanic/Latinos and improve their health outcomes.

Resistant itchy lesions in a young man

Case study A man, 18 years of age, presented with a 6-month history of a widespread itchy rash, more intense at night, which had appeared 1 month after returning from a holiday to the Dominican Republic. The rash initially appeared as white patches affecting the fingers. The patient reported unprotected heterosexual intercourse while on holiday. There was no previous or family history of atopic dermatitis, however, the patient's sister had recently begun to experience similar symptoms. Clinical examination revealed scattered excoriated papules over the trunk (Figure 1), limbs and hands (Figure 2). Intensely itchy nodules were observed on the scrotum (Figure 3). A prolonged course of oral antihistamine in addition to topical corticosteroids did not improve the symptoms. 

An empowerment-based diabetes self-management education program for Hispanic/Latinos: a quasi-experimental pilot study

PURPOSE

The purpose of this pilot study was to evaluate the effects of a culturally sensitive, empowerment-based diabetes self-management education program for Spanish-speaking Hispanic/Latinos.

METHODS

A prospective quasi-experimental repeated measures design tested the effectiveness of the ¡Si, Yo Puedo Controlar Mi Diabetes! diabetes self-management education program. In sum, 144 persons residing in 2 Texas counties at the Texas-Mexico border (Starr and Hidalgo) served as participants. Two groups were formed, an intervention and a control (wait list). Clinical (A1C), cognitive, attitudinal, behavioral, and cultural assessments were collected at baseline and 3 months.

RESULTS

Demographic characteristics for the intervention and control groups were similar. Both groups were predominately female, low income, older than 40 years, and minimally acculturated. Baseline and posttest findings showed that the intervention group had a significant reduction in A1C values; median difference was 0.3 (n = 45), especially for those with higher baseline values. Participants in the intervention group also improved in their self-efficacy and self-care scores.

CONCLUSIONS

Findings from the study suggest that additional dissemination of a diabetes self-management education program for Spanish-speaking Hispanic/Latinos is warranted to improve clinical outcomes and associated diabetes self-efficacy and self-care behaviors.

Three enzymatic steps required for the galactosamine incorporation into core lipopolysaccharide

The core lipopolysaccharides (LPS) of Proteus mirabilis as well as those of Klebsiella pneumoniae and Serratia marcescens are characterized by the presence of a hexosamine-galacturonic acid disaccharide (αHexN-(1,4)-αGalA) attached by an α1,3 linkage to L-glycero-D-manno-heptopyranose II (L-glycero-α-D-manno-heptosepyranose II). In K. pneumoniae, S. marcescens, and some P. mirabilis strains, HexN is D-glucosamine, whereas in other P. mirabilis strains, it corresponds to D-galactosamine. Previously, we have shown that two enzymes are required for the incorporation of D-glucosamine into the core LPS of K. pneumoniae; the WabH enzyme catalyzes the incorporation of GlcNAc from UDP-GlcNAc to outer core LPS, and WabN catalyzes the deacetylation of the incorporated GlcNAc. Here we report the presence of two different HexNAc transferases depending on the nature of the HexN in P. mirabilis core LPS. In vivo and in vitro assays using LPS truncated at the level of galacturonic acid as acceptor show that these two enzymes differ in their specificity for the transfer of GlcNAc or GalNAc. By contrast, only one WabN homologue was found in the studied P. mirabilis strains. Similar assays suggest that the P. mirabilis WabN homologue is able to deacetylate both GlcNAc and GalNAc. We conclude that incorporation of d-galactosamine requires three enzymes: Gne epimerase for the generation of UDP-GalNAc from UDP-GlcNAc, N-acetylgalactosaminyltransferase (WabP), and LPS:HexNAc deacetylase.

Hydrogen sulfide attenuates intestinal ischemia-reperfusion injury when delivered in the post-ischemic period

BACKGROUND AND AIM

To investigate whether pharmacologic post-conditioning of intestinal tissue with hydrogen sulfide (HS) protects against ischemia reperfusion injury (IRI).

METHODS

In vitro, enterocytes were made hypoxic for 1, 2, or 3 h, treated with media containing between 0 and 100 µM HS 20 min prior to the end of the hypoxic period, then returned to normoxia for 3 h. An apoptotic index (AI) was determined for each time point and (HS). In vivo, jejunal ischemia was induced in male Sprague-Dawley rats for 1, 2, or 3 h; 20 min prior to the end of the ischemic period animals were given an intravenous injection of NaHS sufficient to raise the bloodstream concentration to 0, 10 µM, or 100 µM HS. This was followed by jejunal reperfusion for 3 h, histologic processing, and measurement of villus height.

RESULTS

In vitro, there was a significant decrease in AI compared with non-HS-treated control at all time points after treatment with 10 µM HS, and at the 2 h time point with 100 µM HS (P < 0.017). In vivo, after 1 h ischemia, qualitative reduction of injury was noted with 10 µM and 100 µM; after 2 h ischemia, reduction was noted with 10 µM but not 100 µM; and after 3 h ischemia, there was no injury reduction. HS treatment resulted in significant quantitative preservation (P < 0.05) of villus height at all time points and doses, except for 3 h ischemia and delivery of 100 µM (P = 0.129).

CONCLUSIONS

Hydrogen sulfide provides significant protection to intestinal tissues in vitro and in vivo when delivered after the onset of ischemia.

Development of an acellular bioengineered matrix with a dominant vascular pedicle

BACKGROUND

This study assessed the feasibility of creating a tissue engineering platform by decellularization of fasciocutaneous tissue.

MATERIALS AND METHODS

A fasciocutaneous flap based upon the superficial inferior epigastric artery was harvested from the abdominal wall of 8-wk-old male Sprague-Dawley rats. All cellular components were removed by sequential treatment with sodium azide, DNAse, and sodium deoxycholate. The degree of decellularization was qualitatively assessed by histology and quantitatively assessed by spectrophotometry. Persistence of relevant extracellular matrix proteins was shown following staining with orcein and hematoxylin. The duration of circuit patency was determined by continuous perfusion with a peristaltic perfusion pump.

RESULTS

Gross and histologic examination demonstrated removal of cellular constituents with preservation of tissue matrix architecture, including macrochannels and microchannels. This was confirmed by the application of spectrophotometry to DNA isolates, which showed that the decellularized flap retained 4.04 ng/μL DNA, compared with the non-processed control, which retained 37.03 ng/μL DNA, and the acellular control, which was read as having 0.65 ng/μL DNA. The extracellular matrix of vessel walls was shown to remain intact. Peristaltic perfusion of the cannulated pedicle inflow channel with phosphate buffered saline at a rate of 200 μL/min confirmed circuit patency for 6 h.

CONCLUSION

Fasciocutaneous flaps harvested with an intact vascular pedicle and associated tissue vascular network can be successfully decellularized and perfused ex vivo. This methodology, which is scalable to human size tissues, provides promise as a technique for the production of customizable engineered tissues.

One-year surveillance of methicillin-resistant Staphylococcus aureus nasal colonization and skin and soft tissue infections in collegiate athletes

OBJECTIVE

To determine the frequency and clinical importance of methicillin-resistant Staphylococcus aureus (MRSA) colonization in student athletes.

DESIGN

Prospective observational cohort study.

SETTING

A major university in the southeastern United States.

PARTICIPANTS

Student athletes participating in the men's football and women's lacrosse programs (N = 126). Main Exposure Monthly assessment of S aureus nasal colonization.

MAIN OUTCOME MEASURES

Trends in S aureus colonization over time and the occurrence of skin and soft tissue infections.

RESULTS

Methicillin-resistant S aureus nasal colonization varied significantly through the athletic season (4%-23%), peaking during times of highest athletic activity. This increase in colonization was not associated with the development of an outbreak of skin and soft tissue infections, and no single MRSA clone emerged as a dominant isolate.

CONCLUSIONS

During the athletic season, there is a considerable burden of MRSA colonization in student athletes; however, colonization alone appears to be insufficient to trigger an outbreak of staphylococcal infections. A combination of distinct molecular characteristics in the organism and specific host factors may govern the development of staphylococcal disease.

A bifunctional enzyme in a single gene catalyzes the incorporation of GlcN into the Aeromonas core lipopolysaccharide

The core lipopolysaccharide (LPS) of Aeromonas hydrophila AH-3 and Aeromonas salmonicida A450 is characterized by the presence of the pentasaccharide alpha-d-GlcN-(1-->7)-l-alpha-d-Hep-(1-->2)-l-alpha-d-Hep-(1-->3)-l-alpha-d-Hep-(1-->5)-alpha-Kdo. Previously it has been suggested that the WahA protein is involved in the incorporation of GlcN residue to outer core LPS. The WahA protein contains two domains: a glycosyltransferase and a carbohydrate esterase. In this work we demonstrate that the independent expression of the WahA glycosyltransferase domain catalyzes the incorporation of GlcNAc from UDP-GlcNAc to the outer core LPS. Independent expression of the carbohydrate esterase domain leads to the deacetylation of the GlcNAc residue to GlcN. Thus, the WahA is the first described bifunctional glycosyltransferase enzyme involved in the biosynthesis of core LPS. By contrast in Enterobacteriaceae containing GlcN in their outer core LPS the two reactions are performed by two different enzymes.

Molecular analysis of three Aeromonas hydrophila AH-3 (serotype O34) lipopolysaccharide core biosynthesis gene clusters

By the isolation of three different Aeromonas hydrophila strain AH-3 (serotype O34) mutants with an altered lipopolysaccharide (LPS) migration in gels, three genomic regions encompassing LPS core biosynthesis genes were identified and characterized. When possible, mutants were constructed using each gene from the three regions, containing seven, four, and two genes (regions 1 to 3, respectively). The mutant LPS core structures were elucidated by using mass spectrometry, methylation analysis, and comparison with the full core structure of an O-antigen-lacking AH-3 mutant previously established by us. Combining the gene sequence and complementation test data with the structural data and phenotypic characterization of the mutant LPSs enabled a presumptive assignment of all LPS core biosynthesis gene functions in A. hydrophila AH-3. The three regions and the genes contained are in complete agreement with the recently sequenced genome of A. hydrophila ATCC 7966. The functions of the A. hydrophila genes waaC in region 3 and waaF in region 2 were completely established, allowing the genome annotations of the two heptosyl transferase products not previously assigned. Having the functions of all genes involved with the LPS core biosynthesis and most corresponding single-gene mutants now allows experimental work on the role of the LPS core in the virulence of A. hydrophila.

Interoperability with Moby 1.0--it's better than sharing your toothbrush!

The BioMoby project was initiated in 2001 from within the model organism database community. It aimed to standardize methodologies to facilitate information exchange and access to analytical resources, using a consensus driven approach. Six years later, the BioMoby development community is pleased to announce the release of the 1.0 version of the interoperability framework, registry Application Programming Interface and supporting Perl and Java code-bases. Together, these provide interoperable access to over 1400 bioinformatics resources worldwide through the BioMoby platform, and this number continues to grow. Here we highlight and discuss the features of BioMoby that make it distinct from other Semantic Web Service and interoperability initiatives, and that have been instrumental to its deployment and use by a wide community of bioinformatics service providers. The standard, client software, and supporting code libraries are all freely available at http://www.biomoby.org/.

Co-injection of interleukin 8 with the glycoprotein gene from viral haemorrhagic septicemia virus (VHSV) modulates the cytokine response in rainbow trout (Oncorhynchus mykiss)

Since previous results showed that interleukin 8 (IL-8) was induced in rainbow trout (Oncorhynchus mykiss) in response to viral hemorrhagic septicemia virus (VHSV) infection, we have cloned IL-8 in an expression vector (pIL8+) and studied its possible adjuvant effect on the early response to a VHSV immunization model, focusing on the early response of several cytokines induced by a vector coding for the glycoprotein of VHSV (pMCV1.4-G) in the spleen and head kidney. First, we demonstrated that the pIL8+ successfully transcribed IL-8, by induction of IL-8 transcription in the muscle and blood, and by a massive infiltration of neutrophils at the muscle inoculation site. We have studied the effect of pIL8+ co-administration on the expression of two pro-inflammatory cytokines, such as IL-1beta and tumour necrosis factor alpha (TNF-alpha); cytokines that have mainly an inhibitory role, IL-11 and transforming growth factor beta (TGF-beta); and a Th1 type cytokine, IL-18. We demonstrated that the co-administration of pIL8+ with pMCV1.4-G modulates the cytokine response that is induced, mainly by having its effect increasing pro-inflammatory cytokines (IL-1beta and TNF-alpha1), with a greater impact on the spleen, and to a lesser extent in the head kidney. All these data suggest that IL-8 is able to modulate the early cytokine immune response that is produced in response to a DNA vaccine, and therefore, might be a potential immune adjuvant in fish viral vaccination. More work should be done to determine if this modulation has a beneficial effect on protection as seen in other mammal viral models.

The Incorporation of Glucosamine into Enterobacterial Core Lipopolysaccharide

The core lipopolysaccharide (LPS) of Klebsiella pneumoniae is characterized by the presence of disaccharide alphaGlcN-(1,4)-alphaGalA attached by an alpha1,3 linkage to l-glycero-d-manno-heptopyranose II (ld-HeppII). Previously it has been shown that the WabH enzyme catalyzes the incorporation of GlcNAc from UDP-GlcNAc to outer core LPS. The presence of GlcNAc instead of GlcN and the lack of UDP-GlcN in bacteria indicate that an additional enzymatic step is required. In this work we identified a new gene (wabN) in the K. pneumoniae core LPS biosynthetic cluster. Chemical and structural analysis of K. pneumoniae non-polar wabN mutants showed truncated core LPS with GlcNAc instead of GlcN. In vitro assays using LPS truncated at the level of d-galacturonic acid (GalA) and cell-free extract containing WabH and WabN together led to the incorporation of GlcN, whereas none of them alone were able to do it. This result suggests that the later enzyme (WabN) catalyzes the deacetylation of the core LPS containing the GlcNAc residue. Thus, the incorporation of the GlcN residue to core LPS in K. pneumoniae requires two distinct enzymatic steps. WabN homologues are found in Serratia marcescens and some Proteus strains that show the same disaccharide alphaGlcN-(1,4)-alphaGalA attached by an alpha1,3 linkage to ld-HeppII.

Structural studies on the R-type lipopolysaccharide of Aeromonas hydrophila

A rough strain of Aeromonas hydrophila, AH-901, has an R-type lipopolysaccharide with the complete core. The following core structure was established by chemical degradations followed by sugar and methylation analyses along with ESIMS and NMR spectroscopy: [formula: see text] where D-alpha-D-Hep and l-alpha-D-Hep stand for D-glycero- and l-glycero-alpha-D-manno-heptose, respectively; Kdo stands for 3-deoxy-D-manno-oct-2-ulosonic acid; all monosaccharides are in the pyranose form; the degree of substitution with beta-D-Gal is approximately 50%. Lipid A of the lipopolysaccharide has a 1,4(')-bisphosphorylated beta-D-GlcN-(1-->6)-alpha-D-GlcN disaccharide backbone with both phosphate groups substituted with 4-amino-4-deoxyarabinose residues.

Genetic and structural characterization of the core region of the lipopolysaccharide from Serratia marcescens N28b (serovar O4)

The gene cluster (waa) involved in Serratia marcescens N28b core lipopolysaccharide (LPS) biosynthesis was identified, cloned, and sequenced. Complementation analysis of known waa mutants from Escherichia coli K-12, Salmonella enterica, and Klebsiella pneumoniae led to the identification of five genes coding for products involved in the biosynthesis of a shared inner core structure: [L,D-HeppIIIalpha(1-->7)-L,D-HeppIIalpha(1-->3)-L,D-HeppIalpha(1-->5)-KdopI(4<--2)alphaKdopII] (L,D-Hepp, L-glycero-D-manno-heptopyranose; Kdo, 3-deoxy-D-manno-oct-2-ulosonic acid). Complementation and/or chemical analysis of several nonpolar mutants within the S. marcescens waa gene cluster suggested that in addition, three waa genes were shared by S. marcescens and K. pneumoniae, indicating that the core region of the LPS of S. marcescens and K. pneumoniae possesses additional common features. Chemical and structural analysis of the major oligosaccharide from the core region of LPS of an O-antigen-deficient mutant of S. marcescens N28b as well as complementation analysis led to the following proposed structure: beta-Glc-(1-->6)-alpha-Glc-(1-->4))-alpha-D-GlcN-(1-->4)-alpha-D-GalA-[(2<--1)-alpha-D,D-Hep-(2<--1)-alpha-Hep]-(1-->3)-alpha-L,D-Hep[(7<--1)-alpha-L,D-Hep]-(1-->3)-alpha-L,D-Hep-[(4<--1)-beta-D-Glc]-(1-->5)-Kdo. The D configuration of the beta-Glc, alpha-GclN, and alpha-GalA residues was deduced from genetic data and thus is tentative. Furthermore, other oligosaccharides were identified by ion cyclotron resonance-Fourier-transformed electrospray ionization mass spectrometry, which presumably contained in addition one residue of D-glycero-D-talo-oct-2-ulosonic acid (Ko) or of a hexuronic acid. Several ions were identified that differed from others by a mass of +80 Da, suggesting a nonstoichiometric substitution by a monophosphate residue. However, none of these molecular species could be isolated in substantial amounts and structurally analyzed. On the basis of the structure shown above and the analysis of nonpolar mutants, functions are suggested for the genes involved in core biosynthesis.