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1.  Evaluation of the Pharmacokinetic Interaction between Repeated Doses of Rifapentine or Rifampin and a Single Dose of Bedaquiline in Healthy Adult Subjects 
This study assessed the effects of rifapentine or rifampin on the pharmacokinetics of a single dose of bedaquiline and its M2 metabolite in healthy subjects using a two-period single-sequence design. In period 1, subjects received a single dose of bedaquiline (400 mg), followed by a 28-day washout. In period 2, subjects received either rifapentine (600 mg) or rifampin (600 mg) from day 20 to day 41, as well as a single bedaquiline dose (400 mg) on day 29. The pharmacokinetic profiles of bedaquiline and M2 were compared over 336 h after the administration of bedaquiline alone and in combination with steady-state rifapentine or rifampin. Coadministration of bedaquiline with rifapentine or rifampin resulted in lower bedaquiline exposures. The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for the maximum observed concentration (Cmax), area under the concentration-time curve to the last available concentration time point (AUC0–t), and AUC extrapolated to infinity (AUC0–inf) of bedaquiline were 62.19% (53.37 to 72.47), 42.79% (37.77 to 48.49), and 44.52% (40.12 to 49.39), respectively, when coadministered with rifapentine. Similarly, the GMRs and 90% CIs for the Cmax, AUC0–t, and AUC0–inf of bedaquiline were 60.24% (51.96 to 69.84), 41.36% (37.70 to 45.36), and 47.32% (41.49 to 53.97), respectively, when coadministered with rifampin. The Cmax, AUC0–t, and AUC0–inf of M2 were also altered when bedaquiline was coadministered with rifapentine or rifampin. Single doses of bedaquiline, administered alone or with multiple doses of rifapentine or rifampin, were well tolerated, with no safety concerns related to coadministration. Daily administration of rifapentine to patients with tuberculosis presents the same drug interaction challenges as rifampin and other rifamycins. Strong inducers of the cytochrome P450 isoenzyme CYP3A4 should be avoided when considering the use of bedaquiline. (This study is registered at under identifier NCT02216331.)
PMCID: PMC4335826  PMID: 25512422
2.  A Randomized, Placebo-Controlled Study Investigating the Nicotinic α7 Agonist, RG3487, for Cognitive Deficits in Schizophrenia 
Neuropsychopharmacology  2014;39(7):1568-1577.
Effective treatments for cognitive impairment associated with schizophrenia (CIAS) remain an unmet need. Nicotinic α7 receptor agonists may be effective in CIAS. This 8-week (week 1, inpatient; weeks 2–8, outpatient), double-blind, randomized study used Measurement And Treatment Research to Improve Cognition in Schizophrenia (MATRICS) guidelines to investigate the nicotinic α7 partial agonist RG3487 (formerly MEM3454) in CIAS; 215 patients with chronic stable schizophrenia received placebo or RG3487 (5, 15, or 50 mg) added to ongoing treatment with risperidone, paliperidone, or aripiprazole. Primary end point was baseline to week 8 change in MATRICS Consensus Cognitive Battery (MCCB) composite t-score. Secondary outcomes were change in MCCB domain and negative symptom assessment (NSA) scores. The study did not allow for evaluation of nonsmokers. Each RG3487 dose was evaluated using a mixed-effects model repeated measures approach. Mean (SD) baseline MCCB composite t-score was 28.3 (12.0). No significant effect on MCCB composite t-scores was observed with RG3487 (adjusted mean difference (SE) vs placebo: 5 mg: 0.11 (1.39); 15 mg: −1.95 (1.39); 50 mg: −1.13 (1.37); p=0.2–0.9). RG3487 did not improve MCCB domain scores. In a post hoc analysis of patients with moderate negative symptoms, 5 and 50 mg RG3487 vs placebo significantly improved NSA total (−4.45 (p=0.04) and −4.75 (p=0.02), respectively) and global (−0.39 (p=0.04) and −0.55 (p=0.003), respectively) scores. The MCCB did not lead to higher than expected patient withdrawal. RG3487 was generally well tolerated. In patients with stable schizophrenia, RG3487 did not improve cognitive deficits, as assessed by the MCCB; however, in patients with moderate negative symptoms, a post hoc analysis revealed significant improvement of negative symptoms.
PMCID: PMC4023143  PMID: 24549101
acetylcholine; alpha 7 nicotinic receptor; cognition; neuropharmacology; randomized controlled study; schizophrenia; antipsychotics; α7 nicotinic receptor; cognition; randomized controlled study; schizophrenia
3.  Four-Month Moxifloxacin-Based Regimens for Drug-Sensitive Tuberculosis 
The New England journal of medicine  2014;371(17):1577-1587.
Early-phase and preclinical studies suggest that moxifloxacin-containing regimens could allow for effective 4-month treatment of uncomplicated, smear-positive pulmonary tuberculosis.
We conducted a randomized, double-blind, placebo-controlled, phase 3 trial to test the noninferiority of two moxifloxacin-containing regimens as compared with a control regimen. One group of patients received isoniazid, rifampin, pyrazinamide, and ethambutol for 8 weeks, followed by 18 weeks of isoniazid and rifampin (control group). In the second group, we replaced ethambutol with moxifloxacin for 17 weeks, followed by 9 weeks of placebo (isoniazid group), and in the third group, we replaced isoniazid with moxifloxacin for 17 weeks, followed by 9 weeks of placebo (ethambutol group). The primary end point was treatment failure or relapse within 18 months after randomization.
Of the 1931 patients who underwent randomization, in the per-protocol analysis, a favorable outcome was reported in fewer patients in the isoniazid group (85%) and the ethambutol group (80%) than in the control group (92%), for a difference favoring the control group of 6.1 percentage points (97.5% confidence interval [CI], 1.7 to 10.5) versus the isoniazid group and 11.4 percentage points (97.5% CI, 6.7 to 16.1) versus the ethambutol group. Results were consistent in the modified intention-to-treat analysis and all sensitivity analyses. The hazard ratios for the time to culture negativity in both solid and liquid mediums for the isoniazid and ethambutol groups, as compared with the control group, ranged from 1.17 to 1.25, indicating a shorter duration, with the lower bounds of the 95% confidence intervals exceeding 1.00 in all cases. There was no significant difference in the incidence of grade 3 or 4 adverse events, with events reported in 127 patients (19%) in the isoniazid group, 111 (17%) in the ethambutol group, and 123 (19%) in the control group.
The two moxifloxacin-containing regimens produced a more rapid initial decline in bacterial load, as compared with the control group. However, noninferiority for these regimens was not shown, which indicates that shortening treatment to 4 months was not effective in this setting. (Funded by the Global Alliance for TB Drug Development and others; REMoxTB number, NCT00864383.)
PMCID: PMC4277680  PMID: 25196020
4.  Phase I Safety, Pharmacokinetics, and Pharmacogenetics Study of the Antituberculosis Drug PA-824 with Concomitant Lopinavir-Ritonavir, Efavirenz, or Rifampin 
There is an urgent need for new antituberculosis (anti-TB) drugs, including agents that are safe and effective with concomitant antiretrovirals (ARV) and first-line TB drugs. PA-824 is a novel antituberculosis nitroimidazole in late-phase clinical development. Cytochrome P450 (CYP) 3A, which can be induced or inhibited by ARV and antituberculosis drugs, is a minor (∼20%) metabolic pathway for PA-824. In a phase I clinical trial, we characterized interactions between PA-824 and efavirenz (arm 1), lopinavir/ritonavir (arm 2), and rifampin (arm 3) in healthy, HIV-uninfected volunteers without TB disease. Participants in arms 1 and 2 were randomized to receive drugs via sequence 1 (PA-824 alone, washout, ARV, and ARV plus PA-824) or sequence 2 (ARV, ARV with PA-824, washout, and PA-824 alone). In arm 3, participants received PA-824 and then rifampin and then both. Pharmacokinetic sampling occurred at the end of each dosing period. Fifty-two individuals participated. Compared to PA-824 alone, plasma PA-824 values (based on geometric mean ratios) for maximum concentration (Cmax), area under the concentration-time curve from 0 to 24 h (AUC0–24), and trough concentration (Cmin) were reduced 28%, 35%, and 46% with efavirenz, 13%, 17%, and 21% with lopinavir-ritonavir (lopinavir/r) and 53%, 66%, and 85% with rifampin, respectively. Medications were well tolerated. In conclusion, lopinavir/r had minimal effect on PA-824 exposures, supporting PA-824 use with lopinavir/r without dose adjustment. PA-824 exposures, though, were reduced more than expected when given with efavirenz or rifampin. The clinical implications of these reductions will depend upon data from current clinical trials defining PA-824 concentration-effect relationships. (This study has been registered at under registration no. NCT01571414.)
PMCID: PMC4135849  PMID: 24957823
5.  Principal component analysis of atrial fibrillation: Inclusion of posterior ECG leads does not improve correlation with left atrial activity 
Medical Engineering & Physics  2015;37(2):251-255.
•Individual posterior ECG leads better reflect left atrial activity compared to V1.•Surface dominant AF frequency (DAF) calculated using principal component analysis.•Modified 12-lead ECG (including posterior leads) compared to standard 12-lead ECG.•Surface DAF from modified ECG did not correlate stronger with left atrial activity.•Lead V1 dominant in AF principal component from both ECG configurations.
Lead V1 is routinely analysed due to its large amplitude AF waveform. V1 correlates strongly with right atrial activity but only moderately with left atrial activity. Posterior lead V9 correlates strongest with left atrial activity.
(1) To establish whether surface dominant AF frequency (DAF) calculated using principal component analysis (PCA) of a modified 12-lead ECG (including posterior leads) has a stronger correlation with left atrial activity compared to the standard ECG. (2) To assess the contribution of individual ECG leads to the AF principal component in both ECG configurations.
Patients were assigned to modified or standard ECG groups. In the modified ECG, posterior leads V8 and V9 replaced V4 and V6. AF waveform was extracted from one-minute surface ECG recordings using PCA. Surface DAF was correlated with intracardiac DAF from the high right atrium (HRA), coronary sinus (CS) and pulmonary veins (PVs).
96 patients were studied. Surface DAF from the modified ECG did not have a stronger correlation with left atrial activity compared to the standard ECG. Both ECG configurations correlated strongly with HRA, CS and right PVs but only moderately with left PVs. V1 contributed most to the AF principal component in both ECG configurations.
PMCID: PMC4330400  PMID: 25619612
Surface electrocardiogram; Principal component analysis; QRST subtraction; Dominant frequency; Atrial fibrillation; ABS, average beat subtraction; AF, atrial fibrillation; CS, coronary sinus; DAF, dominant atrial fibrillation frequency; ECG, electrocardiogram; HRA, high right atrium; Hz, hertz; LA, left atrial; LVEF, left ventricular ejection fraction; LCPV, left common pulmonary vein; LLPV, left lower pulmonary vein; LUPV, left upper pulmonary vein; PCA, principal component analysis; PCs, principal components; PVs, pulmonary veins; RLPV, right lower pulmonary vein; RUPV, right upper pulmonary vein
6.  Rifampicin and rifapentine significantly reduce concentrations of bedaquiline, a new anti-TB drug 
Bedaquiline is the first drug of a new class approved for the treatment of TB in decades. Bedaquiline is metabolized by cytochrome P450 (CYP) 3A4 to a less-active M2 metabolite. Its terminal half-life is extremely long (5–6 months), complicating evaluations of drug–drug interactions. Rifampicin and rifapentine, two anti-TB drugs now being optimized to shorten TB treatment duration, are potent inducers of CYP3A4. This analysis aimed to predict the effect of repeated doses of rifampicin or rifapentine on the steady-state pharmacokinetics of bedaquiline and its M2 metabolite from single-dose data using a model-based approach.
Pharmacokinetic data for bedaquiline and M2 were obtained from a Phase I study involving 32 individuals each receiving two doses of bedaquiline, alone or together with multiple-dose rifampicin or rifapentine. Sampling was performed over 14 days following each bedaquiline dose. Pharmacokinetic analyses were performed using non-linear mixed-effects modelling. Models were used to simulate potential dose adjustments.
Rifamycin co-administration increased bedaquiline clearance substantially: 4.78-fold [relative standard error (RSE) 9.10%] with rifampicin and 3.96-fold (RSE 5.00%) with rifapentine. Induction of M2 clearance was equally strong. Average steady-state concentrations of bedaquiline and M2 are predicted to decrease by 79% and 75% when given with rifampicin or rifapentine, respectively. Simulations indicated that increasing the bedaquiline dosage to mitigate the interaction would yield elevated M2 concentrations during the first treatment weeks.
Rifamycin antibiotics reduce bedaquiline concentrations substantially. In line with current treatment guidelines for drug-susceptible TB, concomitant use is not recommended, even with dose adjustment.
PMCID: PMC4356204  PMID: 25535219
drug-drug interactions; population pharmacokinetics; tuberculosis
7.  Validation of Cryo-EM Structure of IP3R1 Channel 
About a decade ago, three electron cryomicroscopy (cryo-EM) single particle reconstructions of IP3R1 were reported at low resolution. Disturbingly, these structures bore little similarity to one another, even at the level of quaternary structure. Recently, we published an improved structure of IP3R1 at ~1 nm resolution. However, this structure did not bear any resemblance to any of the three previously published structures, leading to the question of why the new structure should be considered more reliable than the original three. Here we apply several methods, including class-average/map comparisons, tilt-pair validation, and use of multiple refinement software packages, to give strong evidence for the reliability of our recent structure. The map resolution and feature resolvability are assessed with the ‘gold standard’ criterion. This approach is generally applicable to assessing the validity of cryo-EM maps of other molecular machines.
PMCID: PMC3696195  PMID: 23707684
8.  Patient reported outcome measures for cardiac ablation procedures: a multicentre pilot to develop a new questionnaire 
Europace  2014;16(11):1626-1633.
To assess the feasibility of administering Patient Reported Outcomes Measures (PROMs) in patients treated with ablation for cardiac arrhythmias, and to conduct the first stage of development and testing of a new PROM tool.
Methods and results
A new tool was developed by a multidisciplinary team and tested alongside an adaptation of the patient perception of arrhythmia questionnaire (PPAQ) and EQ-5D-5L in a multicentre retrospective audit involving 791 consecutive cardiac arrhythmia patients treated with catheter ablation at three UK centres over 13 months. Data were recorded in the National Cardiac Rhythm Management Database, part of the National Institute for Cardiovascular Outcomes Research. The response rate was 71.9% (n = 569). Patients reported significant improvements across all outcomes and impacts, with reductions in symptoms of 51.7% (heart racing), 33.9% (fatigue) 31.8% (heart flutters), 43.5% (dizziness), 38.6% (breathlessness), 44.2% (chest pressure), 33.1% (trouble concentrating), 15.9% (headache), 28.3% (neck pressure), and 23.4% (fainting) (P < 0.001). The mean number of social days affected reduced by 7.49 days/month (P < 0.001); mean work/school days affected/month reduced by 6.26 (P < 0.001); mean GP/hospital visits reduced by 1.36 days/month (P < 0.001). The procedure met patient expectations in 72% of responders.
The high response rate suggests that the use of PROMs in this patient group is feasible, with rates equalling those of the National PROMs Programme. The results showed that patients experienced significant improvements in their quality of life following ablation, while feedback allowed the tools to be improved. Further work is required to validate these tools; however, the findings suggest that PROMs could be useful in the audit of ablation techniques.
PMCID: PMC4209127  PMID: 24627541
Patient reported outcome measures; PROMs; Cardiac ablation; Arrhythmia; Quality of life
9.  Beyond knockouts: cre resources for conditional mutagenesis 
With the effort of the International Phenotyping Consortium (IMPC) to produce thousands of strains with conditional potential gathering steam, there is growing recognition that it must be supported by a rich toolbox of cre driver strains. The approaches to build cre strains have evolved in both sophistication and reliability, replacing first generation strains with tools that can target individual cell populations with incredible precision and specificity. The modest set of cre drivers generated by individual labs over the past 15+ years is now growing rapidly, thanks to a number of large-scale projects to produce new cre strains for the community. The power of this growing resource, however, depends upon the proper deep characterization of strain function, as even the best designed strain can display a variety of undesirable features that must be considered in experimental design. This must be coupled with the parallel development of informatics tools to provide functional data to the user, and facilitated access to the strains through public repositories. We will discuss the current progress on all of these fronts and the challenges that remain to ensure the scientific community can capitalize on the tremendous number of mouse resources at their disposal.
PMCID: PMC3655717  PMID: 22926223
10.  The Perfect Host: A Mouse Host Embryo Facilitating More Efficient Germ Line Transmission of Genetically Modified Embryonic Stem Cells 
PLoS ONE  2013;8(7):e67826.
There is a continual need to improve efficiency in creating precise genetic modifications in mice using embryonic stem cells (ESCs). We describe a novel approach resulting in 100% germline transmission from competent injected ESCs. We developed an F1 mouse host embryo (Perfect Host, PH) that selectively ablates its own germ cells via tissue-specific induction of diphtheria toxin. This approach allows competent microinjected ESCs to fully dominate the germline, eliminating competition for this critical niche in the developing and adult animal. This is in contrast to conventional methods, where competition from host germ cells results in offspring derived from host cells and ESCs, necessitating extensive breeding of chimeras and genotyping to identify germline. The germline transmission process is also complicated by variability in the actual number of ESCs that colonize the germline niche and the proportion that are germline competent. To validate the PH approach we used ESC lines derived from 129 F1, BALB/cByJ, and BTBR backgrounds as well as an iPS line. Resulting chimeric males produced 194 offspring, all paternally derived from the introduced stem cells, with no offspring being derived from the host genome. We further tested this approach using eleven genetically modified C57BL/6N ESC lines (International Knockout Mouse Consortium). ESC germline transmission was observed in 9/11 (82%) lines using PH blastocysts, compared to 6/11 (55%) when conventional host blastocysts were used. Furthermore, less than 35% (83/240) of mice born in the first litters from conventional chimeras were confirmed to be of ESC-origin. By comparison, 100% (137/137) of the first litter offspring of PH chimeras were confirmed as ESC-derived. Together, these data demonstrate that the PH approach increases the probability of germline transmission and speeds the generation of ESC derived animals from chimeras. Collectively, this approach reduces the time and costs inherent in the production of genetically modified animals.
PMCID: PMC3699516  PMID: 23844102
12.  Bloomsbury report on mouse embryo phenotyping: recommendations from the IMPC workshop on embryonic lethal screening 
Disease Models & Mechanisms  2013;6(3):571-579.
Identifying genes that are important for embryo development is a crucial first step towards understanding their many functions in driving the ordered growth, differentiation and organogenesis of embryos. It can also shed light on the origins of developmental disease and congenital abnormalities. Current international efforts to examine gene function in the mouse provide a unique opportunity to pinpoint genes that are involved in embryogenesis, owing to the emergence of embryonic lethal knockout mutants. Through internationally coordinated efforts, the International Knockout Mouse Consortium (IKMC) has generated a public resource of mouse knockout strains and, in April 2012, the International Mouse Phenotyping Consortium (IMPC), supported by the EU InfraCoMP programme, convened a workshop to discuss developing a phenotyping pipeline for the investigation of embryonic lethal knockout lines. This workshop brought together over 100 scientists, from 13 countries, who are working in the academic and commercial research sectors, including experts and opinion leaders in the fields of embryology, animal imaging, data capture, quality control and annotation, high-throughput mouse production, phenotyping, and reporter gene analysis. This article summarises the outcome of the workshop, including (1) the vital scientific importance of phenotyping embryonic lethal mouse strains for basic and translational research; (2) a common framework to harmonise international efforts within this context; (3) the types of phenotyping that are likely to be most appropriate for systematic use, with a focus on 3D embryo imaging; (4) the importance of centralising data in a standardised form to facilitate data mining; and (5) the development of online tools to allow open access to and dissemination of the phenotyping data.
PMCID: PMC3634642  PMID: 23519032
13.  Mouse Resources for Craniofacial Research 
Genesis (New York, N.Y. : 2000)  2011;49(4):190-199.
The mouse, as a genetically defined and easily manipulated model organism, has played a critical role in unraveling the mechanisms of craniofacial development and dysmorphology. While numerous gene knockout strains that display craniofacial abnormalities and essential recombinase tool strains with craniofacial-specific expression have been generated, many are absent from public repositories. Large-scale, international resource-generating initiatives promise to address this concern, providing a comprehensive set of targeted mutations and a suite of new Cre driver strains. In addition, panels of genetically defined strains provide tools to dissect the multigenic, complex nature of craniofacial development, adding to the foundation of information gained from single gene studies. Continued progress will require awareness and access to these essential mouse resources. In this review, current mouse resources, large-scale efforts and potential future directions will be outlined and discussed.
PMCID: PMC3610317  PMID: 21309071
Knockout; Cre; KOMP; FaceBase
14.  The FaceBase Consortium: A comprehensive program to facilitate craniofacial research 
Developmental biology  2011;355(2):175-182.
The FaceBase Consortium consists of ten interlinked research and technology projects whose goal is to generate craniofacial research data and technology for use by the research community through a central data management and integrated bioinformatics hub. Funded by the National Institute of Dental and Craniofacial Research (NIDCR) and currently focused on studying the development of the middle region of the face, the Consortium will produce comprehensive datasets of global gene expression patterns, regulatory elements and sequencing; will generate anatomical and molecular atlases; will provide human normative facial data and other phenotypes; conduct follow up studies of a completed genome-wide association study; generate independent data on the genetics of craniofacial development, build repositories of animal models and of human samples and data for community access and analysis; and will develop software tools and animal models for analyzing and functionally testing and integrating these data. The FaceBase website ( will serve as a web home for these efforts, providing interactive tools for exploring these datasets, together with discussion forums and other services to support and foster collaboration within the craniofacial research community.
PMCID: PMC3440302  PMID: 21458441
Craniofacial development; Cleft lip and palate; Human genetics; Animal models; Database; Morphometrics
15.  Transcriptional Programs Controlling Perinatal Lung Maturation 
PLoS ONE  2012;7(8):e37046.
The timing of lung maturation is controlled precisely by complex genetic and cellular programs. Lung immaturity following preterm birth frequently results in Respiratory Distress Syndrome (RDS) and Broncho-Pulmonary Dysplasia (BPD), which are leading causes of mortality and morbidity in preterm infants. Mechanisms synchronizing gestational length and lung maturation remain to be elucidated. In this study, we designed a genome-wide mRNA expression time-course study from E15.5 to Postnatal Day 0 (PN0) using lung RNAs from C57BL/6J (B6) and A/J mice that differ in gestational length by ∼30 hr (B6
PMCID: PMC3423373  PMID: 22916088
PLoS ONE  2011;6(11):e26682.
Among all mammals, fetal growth and organ maturation must be precisely synchronized with gestational length to optimize survival at birth. Lack of pulmonary maturation is the major cause of infant mortality in preterm birth. Whether fetal or maternal genotypes influence the close relationship between the length of gestation and lung function at birth is unknown. Structural and biochemical indicators of pulmonary maturity were measured in two mouse strains whose gestational length differed by one day. Shorter gestation in C57BL/6J mice was associated with advanced morphological and biochemical pulmonary development and better perinatal survival when compared to A/J pups born prematurely. After ovarian transplantation, A/J pups were born early in C57BL/6J dams and survived after birth, consistent with maternal control gestational length. Expression of genes critical for perinatal lung function was assessed in A/J pups born after ovarian transfer. A subset of mRNAs important for perinatal respiratory adaptation was selectively induced in the A/J pups born after ovarian transfer. mRNAs precociously induced after ovarian transfer indicated an important role for the transcription factors C/EBPα and CREB in maternally induced lung maturation. We conclude that fetal lung maturation is determined by both fetal and maternal genotypes. Ovarian transfer experiments demonstrated that maternal genotype determines the timing of birth and can influence fetal lung growth and maturation to ensure perinatal survival.
PMCID: PMC3212521  PMID: 22096492
Genome Biology  2011;12(9):R86.
We report the development and optimization of reagents for in-solution, hybridization-based capture of the mouse exome. By validating this approach in a multiple inbred strains and in novel mutant strains, we show that whole exome sequencing is a robust approach for discovery of putative mutations, irrespective of strain background. We found strong candidate mutations for the majority of mutant exomes sequenced, including new models of orofacial clefting, urogenital dysmorphology, kyphosis and autoimmune hepatitis.
PMCID: PMC3308049  PMID: 21917142
PLoS ONE  2010;5(8):e12418.
Preterm birth is an enormous public health problem, affecting over 12% of live births and costing over $26 billion in the United States alone. The causes are complex, but twin studies support the role of genetics in determining gestation length. Despite widespread use of the mouse in studies of the genetics of preterm birth, there have been few studies that actually address the precise natural gestation length of the mouse, and to what degree the timing of labor and birth is genetically determined.
Methodology/Principal Findings
To further develop the mouse as a genetic model of preterm birth, we developed a high-throughput monitoring system and measured the gestation length in 15 inbred strains. Our results show an unexpectedly wide variation in overall gestation length between strains that approaches two full days, while intra-strain variation is quite low. Although litter size shows a strong inverse correlation with gestation length, genetic difference alone accounts for a significant portion of the variation. In addition, ovarian transplant experiments support a primary role of maternal genetics in the determination of gestation length. Preliminary analysis of gestation length in the C57BL/6J-Chr#A/J/NaJ chromosome substitution strain (B.A CSS) panel suggests complex genetic control of gestation length.
Together, these data support the role of genetics in regulating gestation length and present the mouse as an important tool for the discovery of genes governing preterm birth.
PMCID: PMC2928290  PMID: 20811634
While endogenous Myc (c-myc) and Mycn (N-myc) have been reported to be separately dispensable for murine embryonic stem cell (mESC) function, myc greatly enhances induced pluripotent stem (iPS) cell formation and overexpressed c-myc confers LIF-independence upon mESC. To address the role of myc genes in ESC and in pluripotency generally, we conditionally knocked out both c- and N-myc using myc doubly homozygously floxed mESC lines (cDKO). Both lines of myc cDKO mESC exhibited severely disrupted self-renewal, pluripotency, and survival along with enhanced differentiation. Chimeric embryos injected with DKO mESC most often completely failed to develop or in rare cases survived but with severe defects. The essential nature of myc for self-renewal and pluripotency is at least in part mediated through orchestrating pluripotency-related cell cycle and metabolic programs. This study demonstrates that endogenous myc genes are essential for mESC pluripotency and self-renewal as well as providing the first evidence that myc genes are required for early embryogenesis, suggesting potential mechanisms of myc contribution to iPS cell formation.
PMCID: PMC2916696  PMID: 20537458
Embryonic stem cells; Myc; iPS cells; Pluripotency; Self-renewal
The Journal of Clinical Investigation  2009;119(8):2143-2159.
mAbs are becoming increasingly utilized in the treatment of lymphoid disorders. Although Fc-FcγR interactions are thought to account for much of their therapeutic effect, this does not explain why certain mAb specificities are more potent than others. An additional effector mechanism underlying the action of some mAbs is the direct induction of cell death. Previously, we demonstrated that certain CD20-specific mAbs (which we termed type II mAbs) evoke a nonapoptotic mode of cell death that appears to be linked with the induction of homotypic adhesion. Here, we reveal that peripheral relocalization of actin is critical for the adhesion and cell death induced by both the type II CD20-specific mAb tositumomab and an HLA-DR–specific mAb in both human lymphoma cell lines and primary chronic lymphocytic leukemia cells. The cell death elicited was rapid, nonapoptotic, nonautophagic, and dependent on the integrity of plasma membrane cholesterol and activation of the V-type ATPase. This cytoplasmic cell death involved lysosomes, which swelled and then dispersed their contents, including cathepsin B, into the cytoplasm and surrounding environment. The resulting loss of plasma membrane integrity occurred independently of caspases and was not controlled by Bcl-2. These experiments provide what we believe to be new insights into the mechanisms by which 2 clinically relevant mAbs elicit cell death and show that this homotypic adhesion–related cell death occurs through a lysosome-dependent pathway.
PMCID: PMC2719942  PMID: 19620786
Bioinformatics  2009;25(11):1426-1427.
Summary:The Evolutionary Trace Annotation (ETA) Server predicts enzymatic activity. ETA starts with a structure of unknown function, such as those from structural genomics, and with no prior knowledge of its mechanism uses the phylogenetic Evolutionary Trace (ET) method to extract key functional residues and propose a function-associated 3D motif, called a 3D template. ETA then searches previously annotated structures for geometric template matches that suggest molecular and thus functional mimicry. In order to maximize the predictive value of these matches, ETA next applies distinctive specificity filters—evolutionary similarity, function plurality and match reciprocity. In large scale controls on enzymes, prediction coverage is 43% but the positive predictive value rises to 92%, thus minimizing false annotations. Users may modify any search parameter, including the template. ETA thus expands the ET suite for protein structure annotation, and can contribute to the annotation efforts of metaservers.
Availability:The ETA Server is a web application available at
PMCID: PMC2682511  PMID: 19307237
Molecular and Cellular Biology  2008;28(5):1528-1540.
The product of the Snail1 gene is a transcriptional repressor required for triggering the epithelial-to-mesenchymal transition. Furthermore, ectopic expression of Snail1 in epithelial cells promotes resistance to apoptosis. In this study, we demonstrate that this resistance to γ radiation-induced apoptosis caused by Snail1 is associated with the inhibition of PTEN phosphatase. In MDCK cells, mRNA levels of the p53 target gene PTEN are induced after γ radiation; the transfection of Snail1 prevents this up-regulation. Decreased mRNA levels of PTEN were also detected in RWP-1 cells after the ectopic expression of this transcriptional factor. Snail1 represses and associates to the PTEN promoter as detected both by the electrophoretic mobility shift assay and chromatin immunoprecipitation experiments performed with either endogenous or ectopic Snail1. The binding of Snail1 to the PTEN promoter increases after γ radiation, correlating with the stabilization of Snail1 protein, and prevents the association of p53 to the PTEN promoter. These results stress the critical role of Snail1 in the control of apoptosis and demonstrate the regulation of PTEN phosphatase by this transcriptional repressor.
PMCID: PMC2258777  PMID: 18172008
Neoplasia (New York, N.Y.)  2006;8(11):905-916.
The levels and activity of c-Src in colorectal cancer cells increase steadily during the course of colorectal carcino-genesis and are most highly elevated in advanced metastatic disease. However, the effects of increases in c-Src activity on the proliferation of colorectal cancer cells during early and late stages of tumorigenesis remain elusive. To study the consequences of increases in c-Src levels and activity on the growth of colorectal cancer cells in later stages of colorectal carcinogenesis, we developed human colorectal cancer cell lines in which c-Src levels and activity could be inducibly increased by a tightly controlled expression of wild-type c-Src or of the constitutively active mutant of c-Src, c-SrcY527F. Src induction activated multiple signaling pathways (often associated with a proliferative response) but promoted neither cell proliferation in vitro nor tumor growth in a xenograft model in vivo. These results indicate that, in more advanced stages of colorectal carcinogenesis, increases in c-Src levels and activity are likely to have functions other than the direct promotion of tumor growth.
PMCID: PMC1716016  PMID: 17132222
c-Src; colon cancer; proliferation; cell death; Tet On
by Daniel C. Liebler Published by Humana Hardback 150 pages, price £40.00, ISBN 0-89603-991-9 Paperback 210 pages, price £18.95, ISBN 0-89603-992-7
PMCID: PMC1874426

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