Search tips
Search criteria

Results 1-25 (90)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
more »
1.  Palladium-Catalyzed Direct C=H Functionalization of Benzoquinone** 
A direct Pd-catalyzed C=H functionalization of benzoquinone (BQ) can be controlled to give either mono- or disubstituted BQ, including the installation of two different groups in a one-pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents.
PMCID: PMC4502976  PMID: 25302965
benzoquinone; C=H functionalization; palladium; synthetic methods; water
2.  The ages of anxiety – differences across the lifespan in the default mode network functional connectivity in generalized anxiety disorder 
Generalized Anxiety Disorder is one of the most prevalent anxiety disorders, but its neural basis is relatively understudied. This study aims to characterize the functional connectivity in the Default Mode Network (DMN) in Generalized Anxiety Disorder (GAD) across the lifespan.
Design and settings
Functional and structural MRI data were collected with subjects at rest. We analyzed the resting state functional connectivity patterns in the DMN for twenty-seven GAD participants and thirty-nine non-anxious comparison participants. Using a two-way ANOVA, we explored the interaction between age and GAD status on functional connectivity. In GAD participants we analyzed the correlation of functional connectivity indices with the duration of illness and worry severity.
The age-by-anxiety interaction showed a greater anxiety effect on the functional connectivity between the posterior cingulate seed and the medial prefrontal cortex for the older group relative to the younger participants. Longer duration of illness was positively correlated with greater functional connectivity between the posterior cingulate cortex and the insula. Worry severity was inversely correlated with the functional connectivity between the PCC seed and the medial prefrontal cortex.
The presence of GAD, longer duration of illness and more severe worry exacerbate the effects of age on the functional connectivity in the Default Mode Network. These results support the need for tailored research and interventions in late-life anxiety.
PMCID: PMC4028428  PMID: 24254806
Generalized Anxiety Disorder; Functional Connectivity; Resting State; Age effect; Duration of illness; Worry Severity
3.  HIV-Associated Anemia After 96 Weeks on Therapy: Determinants Across Age Ranges in Uganda and Zimbabwe 
Given the detrimental effects of HIV-associated anemia on morbidity, we determined factors associated with anemia after 96 weeks of antiretroviral therapy (ART) across age groups. An HIV-positive cohort (n=3,580) of children age 5–14, reproductive age adults 18–49, and older adults ≥50 from two randomized trials in Uganda and Zimbabwe were evaluated from initiation of therapy through 96 weeks. We conducted logistic and multinomial regression to evaluate common and differential determinants for anemia at 96 weeks on therapy. Prior to initiation of ART, the prevalence of anemia (age 5–11 <10.5 g/dl, 12–14 <11 g/dl, adult females <11 g/dl, adult males <12 g/dl) was 43%, which decreased to 13% at week 96 (p<0.001). Older adults had a significantly higher likelihood of anemia compared to reproductive age adults (OR 2.60, 95% CI 1.44–4.70, p=0.002). Reproductive age females had a significantly higher odds of anemia compared to men at week 96 (OR 2.56, 95% CI 1.92–3.40, p<0.001), and particularly a greater odds for microcytic anemia compared to males in the same age group (p=0.001). Other common factors associated with anemia included low body mass index (BMI) and microcytosis; greater increases in CD4 count to week 96 were protective. Thus, while ART significantly reduced the prevalence of anemia at 96 weeks, 13% of the population continued to be anemic. Specific groups, such as reproductive age females and older adults, have a greater odds of anemia and may guide clinicians to pursue further evaluation and management.
PMCID: PMC4046193  PMID: 24506102
4.  Targeting STAT5 in Hematological Malignancies through Inhibition of the Bromodomain and Extra-Terminal (BET) Bromodomain Protein BRD2 
Molecular cancer therapeutics  2014;13(5):1194-1205.
The transcription factor signal transducer and activator of transcription 5 (STAT5) is constitutively activated in a wide range of leukemias and lymphomas, and drives the expression of genes necessary for proliferation, survival, and self-renewal. Thus, targeting STAT5 is an appealing therapeutic strategy for hematological malignancies. Given the importance of bromodomain-containing proteins in transcriptional regulation, we considered the hypothesis that a pharmacological bromodomain inhibitor could inhibit STAT5-dependent gene expression. We found that the small molecule bromodomain and extra-terminal (BET) bromodomain inhibitor JQ1 decreases STAT5-dependent (but not STAT3-dependent) transcription of both heterologous reporter genes and endogenous STAT5 target genes. JQ1 reduces STAT5 function in leukemia and lymphoma cells with constitutive STAT5 activation, or inducibly activated by cytokine stimulation. Among the BET bromodomain sub-family of proteins, it appears that BRD2 is the critical mediator for STAT5 activity. In experimental models of acute T cell lymphoblastic leukemias, where activated STAT5 contributes to leukemia cell survival, Brd2 knock-down or JQ1 treatment shows strong synergy with tyrosine kinase inhibitors in inducing leukemia cells apoptosis. By contrast, mononuclear cells isolated form umbilical cord blood, which is enriched in normal hematopoietic precursor cells, were unaffected by these combinations. These findings indicate a unique functional association between BRD2 and STAT5, and suggest that combinations of JQ1 and tyrosine kinase inhibitors may be an important rational strategy for treating leukemias and lymphomas driven by constitutive STAT5 activation.
PMCID: PMC4013223  PMID: 24435449
Targeted therapy; transcription factors; leukemias; gene expression; kinase inhibitors
6.  Fold-change of nuclear NF-κB determines TNF-induced transcription in single cells 
Molecular cell  2014;53(6):867-879.
In response to TNF, NF-κB enters the nucleus and promotes inflammatory and stress-responsive gene transcription. Because NF-κB deregulation is associated with many diseases, one might expect strict control of NF-κB localization. However, nuclear NF-κB levels exhibit considerable cell-to-cell variability, even in unstimulated cells. To resolve this paradox and determine how transcription-inducing signals are encoded, we quantified single-cell NF-κB translocation dynamics and transcriptional responses in the same cells. We show that TNF-induced transcription correlates best with fold-change in nuclear NF-κB, not absolute nuclear NF-κB abundance. Using computational modeling, we find that an incoherent feed-forward loop, from competition for binding to κB motifs, could provide ‘memory’ of pre-ligand state necessary for fold-change detection. Experimentally, we observed three gene-specific patterns of transcription that are recapitulated in our model by modulating competition strength alone. Fold-change detection buffers against stochastic variation in signaling molecules and explains how cells tolerate variability in NF-κB abundance and localization.
PMCID: PMC3977799  PMID: 24530305
7.  Granulin, a novel STAT3-interacting protein, enhances STAT3 transcriptional function and correlates with poorer prognosis in breast cancer 
Genes & Cancer  2015;6(3-4):153-168.
Since the neoplastic phenotype of a cell is largely driven by aberrant gene expression patterns, increasing attention has been focused on transcription factors that regulate critical mediators of tumorigenesis such as signal transducer and activator of transcription 3 (STAT3). As proteins that interact with STAT3 may be key in addressing how STAT3 contributes to cancer pathogenesis, we took a proteomics approach to identify novel STAT3-interacting proteins. We performed mass spectrometry-based profiling of STAT3-containing complexes from breast cancer cells that have constitutively active STAT3 and are dependent on STAT3 function for survival. We identified granulin (GRN) as a novel STAT3-interacting protein that was necessary for both constitutive and maximal leukemia inhibitory factor (LIF)induced STAT3 transcriptional activity. GRN enhanced STAT3 DNA binding and also increased the time-integrated amount of LIF-induced STAT3 activation in breast cancer cells. Furthermore, silencing GRN neutralized STAT3-mediated tumorigenic phenotypes including viability, clonogenesis, and migratory capacity. In primary breast cancer samples, GRN mRNA levels were positively correlated with STAT3 gene expression signatures and with reduced patient survival. These studies identify GRN as a functionally important STAT3-interacting protein that may serve as an important prognostic biomarker and potential therapeutic target in breast cancer.
PMCID: PMC4426952  PMID: 26000098
STAT3; interacting protein; breast cancer
8.  Pubertal development in HIV-infected African children on first-line antiretroviral therapy 
AIDS (London, England)  2015;29(5):609-618.
To estimate age at attaining Tanner stages in Ugandan/Zimbabwean HIV-infected children initiating antiretroviral therapy (ART) in older childhood and investigate predictors of delayed puberty, particularly age at ART initiation.
Observational analysis within a randomized trial.
Tanner staging was assessed every 24 weeks from 10 years of age, menarche every 12 weeks and height every 4–6 weeks. Age at attaining different Tanner stages was estimated using normal interval regression, considering predictors using multivariable regression. Growth was estimated using multilevel models with child-specific intercepts and trajectories.
Median age at ART initiation was 9.4 years (inter-quartile range 7.8, 11.3) (n = 582). At the first assessment, the majority (80.2%) were in Tanner stage 1; median follow-up with staging was 2.8 years. There was a strong delaying effect of older age at ART initiation on age at attaining all Tanner stages (P < 0.05) and menarche (P = 0.02); in boys the delaying effect generally weakened with older age. There were additional significant delays associated with greater impairments in pre-ART height-for-age Z-score (P < 0.05) in both sexes and pre-ART BMI-for-age in girls (P < 0.05). There was no evidence that pre-ART immuno-suppression independently delayed puberty or menarche. However, older children/adolescents had significant growth spurts in intermediate Tanner stages, and were still significantly increasing their height when in Tanner stage 5 (P < 0.01).
Delaying ART initiation until older childhood substantially delays pubertal development and menarche, independently of immuno-suppression. This highlights that factors other than CD4+, such as pubertal development, need consideration when making decisions about timing of ART initiation in older children.
PMCID: PMC4342414  PMID: 25710288
Africa; antiretroviral therapy; children; HIV; puberty
9.  STAT3 Induction of MiR-146b Forms a Feedback Loop to Inhibit the NF-κB to IL-6 Signaling Axis and STAT3-Driven Cancer Phenotypes 
Science signaling  2014;7(310):ra11.
Interleukin-6 (IL-6)-mediated activation of signal transducer and activator of transcription 3 (STAT3) is a mechanism by which chronic inflammation can contribute to cancer and is a common oncogenic event. We discovered a pathway the loss of which is associated with persistent STAT3 activation in human cancer. We found that the gene encoding the tumor suppressor microRNA miR-146b is a direct STAT3 target gene and its expression was increased in normal breast epithelial cells but decreased in tumor cells. Methylation of the miR-146b promoter, which inhibited STAT3-mediated induction of expression, was increased in primary breast cancers. Moreover, we found that miR-146b inhibited nuclear factor κB (NF-κB)-dependent production of IL-6, subsequent STAT3 activation, and IL-6/STAT3-driven migration and invasion in breast cancer cells, thereby establishing a negative feedback loop. In addition, higher expression of miR-146b was positively correlated with patient survival in breast cancer subtypes with increased IL6 expression and STAT3 phosphorylation. Our results identify an epigenetic mechanism of crosstalk between STAT3 and NF-κB relevant to constitutive STAT3 activation in malignancy and the role of inflammation in oncogenesis.
PMCID: PMC4233120  PMID: 24473196
10.  Mycobacterial DNA Extraction for Whole-Genome Sequencing from Early Positive Liquid (MGIT) Cultures 
Journal of Clinical Microbiology  2015;53(4):1137-1143.
We developed a low-cost and reliable method of DNA extraction from as little as 1 ml of early positive mycobacterial growth indicator tube (MGIT) cultures that is suitable for whole-genome sequencing to identify mycobacterial species and predict antibiotic resistance in clinical samples. The DNA extraction method is based on ethanol precipitation supplemented by pretreatment steps with a MolYsis kit or saline wash for the removal of human DNA and a final DNA cleanup step with solid-phase reversible immobilization beads. The protocol yielded ≥0.2 ng/μl of DNA for 90% (MolYsis kit) and 83% (saline wash) of positive MGIT cultures. A total of 144 (94%) of the 154 samples sequenced on the MiSeq platform (Illumina) achieved the target of 1 million reads, with <5% of reads derived from human or nasopharyngeal flora for 88% and 91% of samples, respectively. A total of 59 (98%) of 60 samples that were identified by the national mycobacterial reference laboratory (NMRL) as Mycobacterium tuberculosis were successfully mapped to the H37Rv reference, with >90% coverage achieved. The DNA extraction protocol, therefore, will facilitate fast and accurate identification of mycobacterial species and resistance using a range of bioinformatics tools.
PMCID: PMC4365189  PMID: 25631807
11.  Distinct roles of STAT3 and STAT5 in the pathogenesis and targeted therapy of breast cancer 
Molecular and cellular endocrinology  2013;382(1):10.1016/j.mce.2013.03.010.
The transcription factors STAT3 and STAT5 play important roles in the regulation of mammary gland function during pregnancy, lactation, and involution. Given that STAT3 and STAT5 regulate genes involved in proliferation and survival, it is not surprising that inappropriate activation of STAT3 and STAT5 occurs commonly in breast cancer. Although these proteins are structurally similar, they have divergent and opposing effects on gene expression and cellular phenotype. Notably, when STAT5 and STAT3 are activated simultaneously, STAT5 has a dominant effect, and leads to decreased proliferation and increased sensitivity to cell death. Similarly, in breast cancer, activation of both STAT5 and STAT3 is associated with longer patient survival than activation of STAT3 alone. Pharmacological inhibitors of STAT3 and STAT5 are being developed for cancer therapy, though understanding the activation state and functional interaction of STAT3 and STAT5 in a patient's tumor may be critical for the optimal use of this strategy.
PMCID: PMC3732813  PMID: 23531638
Signal transduction; transcription factors; gene expression; oncology
12.  A Randomized Trial of Prolonged Co-trimoxazole in HIV-Infected Children in Africa 
Co-trimoxazole (fixed-dose trimethoprim–sulfamethoxazole) prophylaxis administered before antiretroviral therapy (ART) reduces morbidity in children infected with the human immunodeficiency virus (HIV). We investigated whether children and adolescents receiving long-term ART in sub-Saharan Africa could discontinue co-trimoxazole.
We conducted a randomized, noninferiority trial of stopping versus continuing daily open-label co-trimoxazole in children and adolescents in Uganda and Zimbabwe. Eligible participants were older than 3 years of age, had been receiving ART for more than 96 weeks, were using insecticide-treated bed nets (in malaria-endemic areas), and had not had Pneumocystis jirovecii pneumonia. Coprimary end points were hospitalization or death and adverse events of grade 3 or 4.
A total of 758 participants were randomly assigned to stop or continue co-trimoxazole (382 and 376 participants, respectively), after receiving ART for a median of 2.1 years (interquartile range, 1.8 to 2.3). The median age was 7.9 years (interquartile range, 4.6 to 11.1), and the median CD4 T-cell percentage was 33% (interquartile range, 26 to 39). Participants who stopped co-trimoxazole had higher rates of hospitalization or death than those who continued (72 participants [19%] vs. 48 [13%]; hazard ratio, 1.64; 95% confidence interval [CI], 1.14 to 2.37; P = 0.007; noninferiority not shown). There was no evidence of variation across ages (P = 0.93 for interaction). A total of 2 participants in the prophylaxis-stopped group (1%) died, as did 3 in the prophylaxis-continued group (1%). Most hospitalizations in the prophylaxis-stopped group were for malaria (49 events, vs. 21 in the prophylaxis-continued group) or infections other than malaria (53 vs. 25), particularly pneumonia, sepsis, and meningitis. Rates of adverse events of grade 3 or 4 were similar in the two groups (hazard ratio, 1.20; 95% CI, 0.83 to 1.72; P = 0.33), but more grade 4 adverse events occurred in the prophylaxis-stopped group (hazard ratio, 2.04; 95% CI, 0.99 to 4.22; P = 0.05), with anemia accounting for the largest number of events (12, vs. 2 with continued prophylaxis).
Continuing co-trimoxazole prophylaxis after 96 weeks of ART was beneficial, as compared with stopping prophylaxis, with fewer hospitalizations for both malaria and infection not related to malaria. (Funded by the United Kingdom Medical Research Council and others; ARROW Current Controlled Trials number, ISRCTN24791884.)
PMCID: PMC4264559  PMID: 24382064
13.  Mobile elements drive recombination hotspots in the core genome of Staphylococcus aureus 
Nature communications  2014;5:3956.
Horizontal gene transfer is an important driver of bacterial evolution, but genetic exchange in the core genome of clonal species, including the major pathogen Staphylococcus aureus, is incompletely understood. Here we reveal widespread homologous recombination in S. aureus at the species-level, in contrast to its near-complete absence between closely-related strains. We discover a patchwork of hotspots and coldspots at fine scales falling against a backdrop of broad-scale trends in rate variation. Over megabases, homoplasy rates fluctuate 1.9-fold, peaking towards the origin-of-replication. Over kilobases, we find core recombination hotspots of up to 2.5-fold enrichment situated near faultlines in the genome associated with mobile elements. The strongest hotspots include regions flanking conjugative transposon ICE6013, the staphylococcal cassette chromosome (SCC) and genomic island νSaα. Mobile element-driven core genome transfer represents an opportunity for adaptation and challenges our understanding of the recombination landscape in predominantly clonal pathogens, with important implications for genotype-phenotype mapping.
PMCID: PMC4036114  PMID: 24853639
14.  Impact of second-line antiretroviral regimens on lipid profiles in an African setting: the DART trial sub-study 
Increasing numbers of HIV-infected patients in sub-Saharan Africa are exposed to antiretroviral therapy (ART), but there are few data on lipid changes on first-line ART, and even fewer on second-line.
DART was a randomized trial comparing monitoring strategies in Ugandan/Zimbabwean adults initiating first-line ART and switching to second-line at clinical/immunological failure. We evaluated fasting lipid profiles at second-line initiation and ≥48 weeks subsequently in stored samples from Zimbabwean patients switching before 18 September 2006.
Of 91 patients switched to second-line ART, 65(73%) had fasting samples at switch and ≥48 weeks, 14(15%) died or were lost <48 weeks, 10(11%) interrupted ART for >14 days and 2(2%) had no samples available. 56/65(86%) received ZDV/d4T + 3TC + TDF first-line, 6(9%) ZDV/d4T + 3TC + NVP and 3(5%) ZDV + 3TC with TDF and NVP. Initial second-line regimens were LPV/r + NNRTI in 27(41%), LPV/r + NNRTI + ddI in 33(50%) and LPV/r + TDF + ddI/3TC/ZDV in 6(9%). At second-line initiation median (IQR) TC, LDL-C, HDL-C and TG (mmol/L) were 3.3(2.8-4.0), 1.7(1.3-2.2), 0.7(0.6-0.9) and 1.1(0.8-1.9) respectively. Levels were significantly increased 48 weeks later, by mean (SE) +2.0(0.1), +1.1(0.1), +0.5(0.05) and +0.4(0.2) respectively (p < 0.001; TG p = 0.01). 3% at switch vs 25% 48 weeks later had TC >5.2 mmol/L; 3% vs 25% LDL-C >3.4 mmol/L and 91% vs 41% HDL-C <1.1 mmol/L (p < 0.001). Similar proportions had TG >1.8 mmol/L (0 vs 3%) and TC/HDL-C ≥5 (40% vs 33%) (p > 0.15).
Modest lipid elevations were observed in African patients on predominantly LPV/r + NNRTI-based second-line regimens. Routine lipid monitoring during second-line ART regimens may not be warranted in this setting but individual cardiovascular risk assessment should guide practice.
PMCID: PMC4197260  PMID: 25320632
Antiretroviral therapy; Lipid profile changes; Protease inhibitors; Non-nucleoside reverse transcriptase inhibitors; African setting
15.  Co-Trimoxazole Prophylaxis Is Associated with Reduced Risk of Incident Tuberculosis in Participants in the Swiss HIV Cohort Study 
Co-trimoxazole reduces mortality in HIV-infected adults with tuberculosis (TB), and in vitro data suggest potential antimycobacterial activity of co-trimoxazole. We aimed to evaluate whether prophylaxis with co-trimoxazole is associated with a decreased risk of incident TB in Swiss HIV Cohort Study (SHCS) participants. We determined the incidence of TB per 1,000 person-years from January 1992 to December 2012. Rates were analyzed separately in participants with current or no previous antiretroviral treatment (ART) using Poisson regression adjusted for CD4 cell count, sex, region of origin, injection drug use, and age. A total of 13,431 cohort participants contributed 107,549 person-years of follow-up: 182 patients had incident TB—132 (73%) before and 50 (27%) after ART initiation. The multivariable incidence rate ratios for cumulative co-trimoxazole exposure per year for persons with no previous ART and current ART were 0.70 (95% confidence interval [CI], 0.55 to 0.89) and 0.87 (95% CI, 0.74 to 1.0), respectively. Co-trimoxazole may prevent the development of TB among HIV-positive persons, especially among those with no previous ART.
PMCID: PMC4023723  PMID: 24514096
16.  Risk of uterine cancer in symptomatic women in primary care: case–control study using electronic records 
The British Journal of General Practice  2013;63(614):e643-e648.
Uterine cancer is the fourth most common cancer in women in the UK, with approximately 7700 new diagnoses and 1700 deaths annually.
To identify and quantify features of uterine cancer in primary care.
Design and setting
Case–control study using electronic primary care records in primary care in the UK.
Putative features of uterine cancer were identified in the year before diagnosis, and odds ratios (ORs) calculated using conditional logistic regression. Positive predictive values (PPVs) were calculated for women who consulted.
A total of 2732 women aged ≥40 years with uterine cancer between 2000 and 2009, and 9537 age-, sex- and practice-matched controls were selected from the General Practice Research Database. The median age at diagnosis was 67 years. Nine features were significantly associated with uterine cancer: postmenopausal bleeding (OR = 160; 95% confidence interval [CI] = 100 to 240), excessive vaginal bleeding (OR = 22; 95% CI = 12 to 42), irregular menstruation (OR = 42; 95% CI = 27 to −63), vaginal discharge (OR = 14; 95% CI = 10 to 21), haematuria (OR = 8.7; 95% CI = 5.0 to 15), abdominal pain (OR = 2.0; 95% CI = 1.4 to 2.8), low haemoglobin (OR = 2.1; 95% CI = 1.5 to 2.9), raised platelets (OR = 1.5; 95% CI = 1.0 to 2.3), and raised glucose (OR = 1.4; 95% CI = 1.1 to 1.8); all P<0.01, other than raised platelets, P = 0.05 and raised glucose, P = 0.02. In the year before diagnosis, 1725 (63%) cases had a record of abnormal vaginal bleeding compared to 135 (1%) controls. The PPV of uterine cancer with postmenopausal bleeding was 4%, and was higher in women with multiple or repeated symptoms.
This study confirms the importance of several features, particularly postmenopausal bleeding, for uterine cancer. Haematuria is an important risk marker. The results of this study may inform GPs in the selection of women for investigation and should assist the NICE in their update of GP referral guidance.
PMCID: PMC3750804  PMID: 23998845
diagnosis; general practice; primary health care; uterine neoplasms
17.  MRI Predictors of Treatment Response in Late-Life Depression 
In older adults, depression not only results in more years lived with disability than any other disease, but it also carries additional risk for suicide, medical comorbidities, and family care-giving burden. Because it can take many months to identify an effective treatment regimen, it is of upmost importance to shorten the window of time and identify early on what medication(s) and dosages will work effectively for individuals suffering from depression. Late-life depression (LLD) has been associated with greater burden of age-related changes, including atrophy, white matter ischemic changes, and alterations in functional connectivity (FC). Depression in midlife has been shown to alter affective reactivity and regulation, and functional magnetic resonance imaging (fMRI) studies in LLD have replicated the same abnormalities. Effective treatment can normalize these alterations. This article provides a review of the current literature using structural and functional neuroimaging to identify magnetic resonance imaging (MRI) predictors of treatment response in LLD. The majority of the literature on structural MRI has focused on the vascular depression hypothesis, and studies support the view that loss of brain volume and white matter integrity is associated with poorer treatment outcomes. Studies using fMRI have reported that lower task-based activity in the prefrontal cortex (PFC) and limbic regions is associated with poorer outcome. These imaging markers may be integrated into clinical decision-making to better treatment outcomes in the future.
PMCID: PMC4103612  PMID: 24381231
19.  Development of an oligonucleotide-based fluorescence assay for the identification of tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitors 
Analytical Biochemistry  2014;454(100):17-22.
Topoisomerase 1 (TOP1) generates transient nicks in the DNA to relieve torsional stress encountered during the cellular processes of transcription, replication, and recombination. At the site of the nick there is a covalent linkage of TOP1 with DNA via a tyrosine residue. This reversible TOP1-cleavage complex intermediate can become trapped on DNA by TOP1 poisons such as camptothecin, or by collision with replication or transcription machinery, thereby causing protein-linked DNA single- or double-strand breaks and resulting in cell death. Tyrosyl-DNA phosphodiesterase 1 (TDP1) is a key enzyme involved in the repair of TOP1-associated DNA breaks via hydrolysis of 3′-phosphotyrosine bonds. Inhibition of TDP1 is therefore an attractive strategy for targeting cancer cells in conjunction with TOP1 poisons. Existing methods for monitoring the phosphodiesterase activity of TDP1 are generally gel based or of high cost. Here we report a novel, oligonucleotide-based fluorescence assay that is robust, sensitive, and suitable for high-throughput screening of both fragment and small compound libraries for the detection of TDP1 inhibitors. We further validated the assay using whole cell extracts, extending its potential application to determine of TDP1 activity in clinical samples from patients undergoing chemotherapy.
PMCID: PMC4007590  PMID: 24637157
TDP1; Assay; High-throughput screen; Fragment; Inhibitor; Topoisomerase
20.  Dynamics of acquisition and loss of carriage of Staphylococcus aureus strains in the community: The effect of clonal complex☆☆☆ 
The Journal of Infection  2014;68(5):426-439.
Staphylococcus aureus nasal carriage increases infection risk. However, few studies have investigated S. aureus acquisition/loss over >1 year, and fewer still used molecular typing.
1123 adults attending five Oxfordshire general practices had nasal swabs taken. 571 were re-swabbed after one month then every two months for median two years. All S. aureus isolates were spa-typed. Risk factors were collected from interviews and medical records.
32% carried S. aureus at recruitment (<1% MRSA). Rates of spa-type acquisition were similar in participants S. aureus positive (1.4%/month) and negative (1.8%/month, P = 0.13) at recruitment. Rates were faster in those carrying clonal complex (CC)15 (adjusted (a)P = 0.03) or CC8 (including USA300) (aP = 0.001) at recruitment versus other CCs. 157/274 (57%) participants S. aureus positive at recruitment returning ≥12 swabs carried S. aureus consistently, of whom 135 carried the same spa-type. CC22 (including EMRSA-15) was more prevalent in long-term than intermittent spa-type carriers (aP = 0.03). Antibiotics transiently reduced carriage, but no other modifiable risk factors were found.
Both transient and longer-term carriage exist; however, the approximately constant rates of S. aureus gain and loss suggest that ‘never’ or truly ‘persistent’ carriage are rare. Long-term carriage varies by strain, offering new explanations for the success of certain S. aureus clones.
PMCID: PMC4003537  PMID: 24393651
Staphylococcus aureus; Molecular epidemiology; Colonisation; spa-typing; Carriage duration
21.  Phase II trial of standard versus increased transfusion volume in Ugandan children with acute severe anemia 
BMC Medicine  2014;12:67.
Severe anemia (SA, hemoglobin <6 g/dl) is a leading cause of pediatric hospital admission in Africa, with significant in-hospital mortality. The underlying etiology is often infectious, but specific pathogens are rarely identified. Guidelines developed to encourage rational blood use recommend a standard volume of whole blood (20 ml/kg) for transfusion, but this is commonly associated with a frequent need for repeat transfusion and poor outcome. Evidence is lacking on what hemoglobin threshold criteria for intervention and volume are associated with the optimal survival outcomes.
We evaluated the safety and efficacy of a higher volume of whole blood (30 ml/kg; Tx30: n = 78) against the standard volume (20 ml/kg; Tx20: n = 82) in Ugandan children (median age 36 months (interquartile range (IQR) 13 to 53)) for 24-hour anemia correction (hemoglobin >6 g/dl: primary outcome) and 28-day survival.
Median admission hemoglobin was 4.2 g/dl (IQR 3.1 to 4.9). Initial volume received followed the randomization strategy in 155 (97%) patients. By 24-hours, 70 (90%) children in the Tx30 arm had corrected SA compared to 61 (74%) in the Tx20 arm; cause-specific hazard ratio = 1.54 (95% confidence interval 1.09 to 2.18, P = 0.01). From admission to day 28 there was a greater hemoglobin increase from enrollment in Tx30 (global P <0.0001). Serious adverse events included one non-fatal allergic reaction and one death in the Tx30 arm. There were six deaths in the Tx20 arm (P = 0.12); three deaths were adjudicated as possibly related to transfusion, but none secondary to volume overload.
A higher initial transfusion volume prescribed at hospital admission was safe and resulted in an accelerated hematological recovery in Ugandan children with SA. Future testing in a large, pragmatic clinical trial to establish the effect on short and longer-term survival is warranted.
Trial registration
ClinicalTrials.Gov identifier: NCT01461590 registered 26 October 2011.
Please see related commentary article
PMCID: PMC4101869  PMID: 24767094
Transfusion; Severe anemia; African children; Clinical trial; Infectious disease
22.  STAT3 Activity and Function in Cancer: Modulation by STAT5 and miR-146b 
Cancers  2014;6(2):958-968.
The transcription factor STAT3 regulates genes that control critical cellular processes such as proliferation, survival, pluripotency, and motility. Thus, under physiological conditions, the transcriptional function of STAT3 is tightly regulated as one part of a complex signaling matrix. When these processes are subverted through mutation or epigenetic events, STAT3 becomes highly active and drives elevated expression of genes underlying these phenotypes, leading to malignant cellular behavior. However, even in the presence of activated STAT3, other cellular modulators can have a major impact on the biological properties of a cancer cell, which is reflected in the clinical behavior of a tumor. Recent evidence has suggested that two such key modulators are the activation status of other STAT family members, particularly STAT5, and the expression of STAT3-regulated genes that are part of negative feedback circuits, including microRNAs such as miR-146b. With attention to these newly emerging areas, we will gain greater insight into the consequence of STAT3 activation in the biology of human cancers. In addition, understanding these subtleties of STAT3 signaling in cancer pathogenesis will allow the development of more rational molecular approaches to cancer therapy.
PMCID: PMC4074811  PMID: 24762632
signal transduction; gene transcription; molecular oncology
24.  Diverse Sources of C. difficile Infection Identified on Whole-Genome Sequencing 
The New England journal of medicine  2013;369(13):10.1056/NEJMoa1216064.
It has been thought that Clostridium difficile infection is transmitted predominantly within health care settings. However, endemic spread has hampered identification of precise sources of infection and the assessment of the efficacy of interventions.
From September 2007 through March 2011, we performed whole-genome sequencing on isolates obtained from all symptomatic patients with C. difficile infection identified in health care settings or in the community in Oxfordshire, United Kingdom. We compared single-nucleotide variants (SNVs) between the isolates, using C. difficile evolution rates estimated on the basis of the first and last samples obtained from each of 145 patients, with 0 to 2 SNVs expected between transmitted isolates obtained less than 124 days apart, on the basis of a 95% prediction interval. We then identified plausible epidemiologic links among genetically related cases from data on hospital admissions and community location.
Of 1250 C. difficile cases that were evaluated, 1223 (98%) were successfully sequenced. In a comparison of 957 samples obtained from April 2008 through March 2011 with those obtained from September 2007 onward, a total of 333 isolates (35%) had no more than 2 SNVs from at least 1 earlier case, and 428 isolates (45%) had more than 10 SNVs from all previous cases. Reductions in incidence over time were similar in the two groups, a finding that suggests an effect of interventions targeting the transition from exposure to disease. Of the 333 patients with no more than 2 SNVs (consistent with transmission), 126 patients (38%) had close hospital contact with another patient, and 120 patients (36%) had no hospital or community contact with another patient. Distinct subtypes of infection continued to be identified throughout the study, which suggests a considerable reservoir of C. difficile.
Over a 3-year period, 45% of C. difficile cases in Oxfordshire were genetically distinct from all previous cases. Genetically diverse sources, in addition to symptomatic patients, play a major part in C. difficile transmission. (Funded by the U.K. Clinical Research Collaboration Translational Infection Research Initiative and others.)
PMCID: PMC3868928  PMID: 24066741
25.  High Level of Viral Suppression and Low Switch Rate to Second-Line Antiretroviral Therapy among HIV-Infected Adult Patients Followed over Five Years: Retrospective Analysis of the DART Trial 
PLoS ONE  2014;9(3):e90772.
In contrast to resource-rich countries, most HIV-infected patients in resource-limited countries receive treatment without virological monitoring. There are few long-term data, in this setting, on rates of viral suppression or switch to second-line antiretroviral therapy. The DART trial compared clinically driven monitoring (CDM) versus routine laboratory (CD4/haematology/biochemistry) and clinical monitoring (LCM) in HIV-infected adults initiating therapy. There was no virological monitoring in either study group during follow-up, but viral load was measured in Ugandan participants at trial closure. Two thousand three hundred and seventeen (2317) participants from this country initiated antiretroviral therapy with zidovudine/lamivudine plus tenofovir (n = 1717), abacavir (n = 300), or nevirapine (n = 300). Of 1896 (81.8%) participants who were alive and in follow-up at trial closure (median 5.1 years after therapy initiation), 1507 (79.5%) were on first-line and 389 (20.5%) on second-line antiretroviral therapy. The overall switch rate after the first year was 5.6 per 100 person-years; the rate was substantially higher in participants with low baseline CD4 counts (<50 cells/mm3). Among 1207 (80.1%) first-line participants with viral load measured, HIV RNA was <400 copies/ml in 963 (79.8%), 400–999 copies/ml in 37 (3.1%), 1,000–9,999 copies/ml in 110 (9.1%), and ≥10,000 copies/ml in 97 (8.0%). The proportion with HIV RNA <400 copies/ml was slightly lower (difference 7.1%, 95% CI 2.5 to 11.5%) in CDM (76.3%) than in LCM (83.4%). Among 252 (64.8%) second-line participants with viral load measured (median 2.3 years after switch), HIV RNA was <400 copies/ml in 226 (89.7%), with no difference between monitoring strategies. Low switch rates and high, sustained levels of viral suppression are achievable without viral load or CD4 count monitoring in the context of high-quality clinical care.
Trial Registration:
PMCID: PMC3953124  PMID: 24625508

Results 1-25 (90)