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Measuring HIV vaccine efficacy.

Some HIV vaccine candidates have a potential VE I (vaccine efficacy for infectiousness) type effect, which tends to reduce the viral load and may reduce infectiousness of an infected individual. In general, the efficacy of this kind of vaccine is very difficult to assess because it requires information on contacts of vaccinated infected individuals, and current methods to estimate VE I rely on the time elapsed between infections of an individual and his/her sexual partner, thus making infection of the sexual partner necessary to assess the efficacy. To avoid behavioural changes that may affect the estimates, HIV status is kept undisclosed to participants, which raises many ethical questions. Here we present a method that allows immediate notification of HIV status to both members of a couple, reducing the risk of infection when one of them has not been infected and allowing immediate medical treatment. The method allows for estimation of any VE I and VE S (vaccine efficacy for susceptibility) effect, and it is robust to the most common situations found in these type of studies, namely: differential risk of participants, staggered enrollment and small sample sizes.

AIDS Vaccines↗

Comparison of the cost-effectiveness of milnacipran (a SNRI) with TCAs and SSRIs: a modeling approach.

A simulation model based on the theory of clinical decision analysis was used to compare outcomes and costs when treating patients with major depressive episodes using either a selective serotonin re-uptake inhibitor (SSRI) or a tricyclic antidepressant (TCA), in comparison with milnacipran (a serotonin), and a norepinephrine re-uptake inhibitor (SNRI). The clinical data used were taken from published meta-analyses. This analysis supports: (1) a comparable efficacy of milnacipran and TCA with a better tolerance; and, (2) an advantage of milnacipran over SSRI for efficacy with a comparable tolerance. Based on these findings, a decision tree was constructed with the assistance of a panel of psychiatrists in order to provide a model of usual clinical practice. Estimates not available from clinical studies were obtained either from literature analysis or from the panel. Economic appraisal was performed according to the viewpoint of the French national sickness fund (sécurité sociale), and expenditure assessment was limited to direct costs (hospitalizations, antidepressant medications, visits, and laboratory tests). The results suggest that milnacipran is a cost-effective alternative: the expected cost of treatment per depressive episode is lower than either a French representative panel of TCAs (a saving of 288 FF), or SSRIs (a savings of 961 FF). The expected length of clinical remission is slightly higher than comparators. The robustness of these findings was supported by sensitivity analyses.

Adrenergic Antagonists↗

Depression during mania. Treatment response to lithium or divalproex.

BACKGROUND: Little information exists from controlled studies about clinical characteristics that predict treatment response in mania. The presence of depressive symptoms during manic episodes may be associated with poor response to psychopharmacological treatments. This is an investigation of the relation between depressive symptoms and treatment response in acute manic episodes. METHODS AND DESIGN: In a parallel-group, double-blind study, 179 patients hospitalized for acute manic episodes were randomized to receive divalproex sodium, lithium carbonate, or placebo (ratio, 2:1:2). The study was carried out at 9 academic medical centers. Patients had comprehensive evaluations of behavior and symptoms before and during 3 weeks of treatment. The primary outcome measure, change in mania factor scores derived from the Schedule for Affective Disorders and Schizophrenia: Change Version, was compared in patients with and without depressive symptoms at baseline according to nurse- or physician-rated scales. RESULTS: Depressive symptoms were associated with poor antimanic response to lithium and with better response to divalproex. This was not due to differences in overall severity of illness, substance abuse, gender, age, or history. CONCLUSIONS: These data suggest that even a modest level of pretreatment depression-related symptoms is a robust predictor of lithium nonresponse, and is associated with better response to divalproex. Although their overall efficacy in acute mania is similar, lithium and divalproex may be most effective in clinically and biologically distinct groups of patients.

Adult↗

TEDOR with adiabatic inversion pulses: Resonance assignments of 13C/15N labelled RNAs.

We have examined via numerical simulations the performance characteristics of different 15N RF pulse schemes employed in the transferred echo double resonance (TEDOR) experimental protocol for generating 13C-15N dipolar chemical shift correlation spectra of isotopically labelled biological systems at moderate MAS frequencies (omega(r) approximately 10 kHz). With an 15N field strength of approximately 30-35 kHz that is typically available in 5 mm triple resonance MAS NMR probes, it is shown that a robust TEDOR sequence with significant tolerance to experimental imperfections sa as H1 inhomogeneity and resonance offsets can be effectively implemented using adiabatic heteronuclear dipolar recoupling pulse schemes. TEDOR-based 15N-13C and 15N-13C-13C chemical shift correlation experiments were carried out for obtaining 13C and 15N resonance assignments of an RNA composed of 97 (CUG) repeats which has been implicated in the neuromuscular disease myotonic dystrophy.

Carbon Isotopes↗

Pharmacological treatment of severely depressed patients: a meta-analysis comparing efficacy of mirtazapine and amitriptyline.

Efficacy data were available from 405 severely depressed patients (baseline 17-item Hamilton Rating Scale for Depression-HAMD scores > or = 25) participating in randomized, double-blind, amitriptyline-controlled studies of mirtazapine. Main efficacy variable were changes from baseline in the group mean 17-item HAMD scores and responder rates. Secondary efficacy variables were changes in depressed mood item on the HAMD and in factors derived from the 17-item HAMD scale. Treatment with either mirtazapine or amitriptyline resulted in robust reductions of baseline HAMD scores and in similar and high percentages of responders. Both drugs produced favourable effects on depressed mood and on symptoms commonly associated with depression, such as anxiety, sleep and vegetative disturbances. There were neither statistically significant nor clinically relevant differences between mirtazapine and amitriptyline at any assessment point nor at endpoint. The results demonstrate that the new antidepressant mirtazapine and the tricyclic antidepressant amitriptyline are equally effective in the treatment of severely depressed patients.

Adolescent↗

Physical and functional interaction between the mini-chromosome maintenance-like DNA helicase and the single-stranded DNA binding protein from the crenarchaeon Sulfolobus solfataricus.

Mini-chromosome Maintenance (MCM) proteins play an essential role in both initiation and elongation phases of DNA replication in Eukarya. Genes encoding MCM homologs are present also in the genomic sequence of Archaea and the MCM-like protein from the euryarchaeon Methanobacterium thermoautotrophicum (Mth MCM) was shown to possess a robust ATP-dependent 3'-5' DNA helicase activity in vitro. Herein, we report the first biochemical characterization of a MCM homolog from a crenarchaeon, the thermoacidophile Sulfolobus solfataricus (Sso MCM). Gel filtration and glycerol gradient centrifugation experiments indicate that the Sso MCM forms single hexamers (470 kDa) in solution, whereas the Mth MCM assembles into double hexamers. The Sso MCM has NTPase and DNA helicase activity, which preferentially acts on DNA duplexes containing a 5'-tail and is stimulated by the single-stranded DNA binding protein from S. solfataricus (Sso SSB). In support of this functional interaction, we demonstrated by immunological methods that the Sso MCM and SSB form protein.protein complexes. These findings provide the first in vitro biochemical evidence of a physical/functional interaction between a MCM complex and another replication factor and suggest that the two proteins may function together in vivo in important DNA metabolic pathways.

Adenosine Triphosphatases↗

Economic analysis of Neoral in de novo renal transplant patients in Canada.

This pilot economic evaluation was performed as part of the Canadian arm of an international randomized, controlled, double-blind safety and tolerability trial (OLM-105/NOF-2). The clinical study compared the safety and tolerability of a new microemulsion oral formulation of cyclosporine A (Neoral) with the oral cyclosporine. A preparation currently in use (Sandimmune SGC)/(SGC). To assess the economic impact of Neoral in newly grafted renal transplant patients, primary cost data were collected at the five participating Canadian centers and evaluated from the Ministry of Health (MOH) and hospital perspectives. The results of this cost analysis are presented in this paper. Since the new formulation has shown more consistent absorption and a more predictable pharmacokinetic profile, medical resource utilization and, consequently, cost of treatment could be expected to be lower for those renal transplant recipients treated with Neoral than for those receiving standard SGC. The findings of this study support this hypothesis. Robustness of the conclusion was confirmed with sensitivity analyses. Reduced health care costs for patients treated with Neoral were primarily a result of fewer hospitalization days and lower physician costs for inpatient and outpatient procedures.

Administration, Oral↗

Effects of acute tryptophan depletion on executive function in healthy male volunteers.

BACKGROUND: Neurocognitive impairment is frequently described in a number of psychiatric disorders and may be a direct consequence of serotonergic dysfunction. As impairments in executive functions are some of the most frequently described, the purpose of this study was to examine the performance of normal volunteers on a range of executive tasks following a transient reduction of central serotonin (5-HT) levels using the method of acute tryptophan depletion (ATD). METHODS: Fifteen healthy male subjects participated in a within-subject, double-blind, counterbalanced crossover study. ATD was induced by ingestion of a 100 g amino-acid drink. Executive function was evaluated using the Wisconsin Card Sorting Test, Stroop, Verbal Fluency and Trail Making. Visual analogue scales were administered to assess mood. RESULTS: Plasma free and total tryptophan concentrations were significantly reduced by the depleting drink (P < 0.001). ATD selectively improved motor speed/ attention on the Trails A test (P = 0.027), with no effect on subjective ratings of mood. Interaction effects between drink and the order of drink administration were observed on most neurocognitive tests. CONCLUSIONS: The improvement in simple motor speed/ attention following ATD is in keeping with the ascribed role of 5-HT in the cortex, however performance on tests of executive function is not robustly altered. The presence of interaction effects on most tasks suggests that subtle changes may occur but are masked, possibly by simple learning effects, in the context of a crossover design. This has implications for the design of future studies, particularly those examining executive functions.

Adolescent↗

Association of rheumatoid arthritis treatment response and disease duration with declines in serum levels of IgM rheumatoid factor and anti-cyclic citrullinated peptide antibody.

OBJECTIVE: To examine the association of treatment response and disease duration with changes in rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody levels among patients with rheumatoid arthritis (RA). METHODS: The study sample included 66 RA patients who completed double-blind, randomized clinical protocols and for whom baseline and followup serum samples were available. Anti-CCP and RF levels were measured using commercially available assay kits. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to describe the association of response and disease duration with declines in antibody levels. RESULTS: Patients had a mean +/- SD age of 49.9 +/- 12.0 years and were predominantly female (n = 51; 77%). The mean +/- SD duration between the times at which the baseline and followup serum samples were obtained was 13.7 +/- 8.6 months. Among the 64 subjects with positive antibody at baseline, 33 (52%) experienced a > or =25% reduction in the anti-CCP antibody level during the course of treatment, and 35 patients (55%) had a > or =25% reduction in RF. After adjustment for the baseline anti-CCP antibody level, only a shorter disease duration (< or =12 months) was significantly associated with a decline in the level of anti-CCP antibody (OR 3.0, 95% CI 1.0-8.8), and no association with treatment response was observed. Conversely, treatment response was the only significant determinant of a decrease in RF levels (OR 3.6, 95% CI 1.2-10.4). CONCLUSION: Shorter disease duration predicts greater declines in anti-CCP antibody levels with treatment in RA. Although treatment response is a robust determinant of a decrease in RF, it does not appear to be associated with declines in the anti-CCP antibody level.

Antirheumatic Agents↗

Transdermal nicotine maintenance attenuates the subjective and reinforcing effects of intravenous nicotine, but not cocaine or caffeine, in cigarette-smoking stimulant abusers.

The effects of transdermal nicotine maintenance on the subjective, reinforcing, and cardiovascular effects of intravenously administered cocaine, caffeine, and nicotine were examined using double-blind procedures in nine volunteers with histories of using tobacco, caffeine, and cocaine. Each participant was exposed to two chronic drug maintenance phases (21 mg/day nicotine transdermal patch and placebo transdermal patch). Within each drug phase, the participant received intravenous injections of placebo, cocaine (15 and 30 mg/70 kg), caffeine (200 and 400 mg/70 kg), and nicotine (1.0 and 2.0 mg/70 kg) in mixed order across days. Subjective and cardiovascular data were collected before and repeatedly after drug or placebo injection. Reinforcing effects were also assessed after each injection with a Drug vs Money Multiple-Choice Form. Intravenous cocaine produced robust dose-related increases in subjective and reinforcing effects; these effects were not altered by nicotine maintenance. Intravenous caffeine produced elevations on several subjective ratings; nicotine maintenance did not affect these ratings. Under the placebo maintenance condition, intravenous nicotine produced robust dose-related subjective effects, with maximal increases similar to the high dose of cocaine; nicotine maintenance significantly decreased the subjective and reinforcing effects of intravenous nicotine. The results of the present study demonstrate that chronic nicotine maintenance produces tolerance to the effects of intravenous nicotine, but does not affect the subjective or reinforcing effects of cocaine or caffeine.

Administration, Cutaneous↗

Integration of novel agents in the treatment of colorectal cancer.

Two of the most promising new targets in the treatment of colorectal cancer are the epithelial growth factor receptor (EGFR) and the vascular endothelial growth factor (VEGF). Agents that inhibit the EGFR or bind to VEGF have demonstrated clinical activity as single agents and in combination with chemotherapy in phase II and phase III clinical trials. The most promising of these agents are cetuximab, which blocks the binding of EGF and transforming growth factor alpha (TGF-alpha) to EGFR, and bevacizumab, which binds free VEGF. Cetuximab and irinotecan have been evaluated in two clinical studies in the USA (IMCL CP02-0141 and IMCL CP02-9923). Study IMCL CP02-0141 evaluated the antitumor activity of single-agent cetuximab in patients with irinotecan-refractory, EGFR-positive metastatic colorectal carcinoma. There were 6 partial responses in 57 treated patients, for a response rate of 10.5%. Study IMCL CP02-9923 evaluated the combination of cetuximab and irinotecan in a total of 139 patients enrolled at 27 study sites. In this trial 22.5% of patients with progressive disease on irinotecan achieved an objective response (19% by investigator assessment) showing that the combination of cetuximab and irinotecan has antitumor activity in this population. A large randomized phase II trial evaluating similar study populations in Europe confirmed these findings, demonstrating response rates for cetuximab/irinotecan and cetuximab alone of 22.9% and 10.8%, respectively. The other promising agent bevacizumab is a humanized variant of the anti-VEGF monoclonal antibody. VEGF is produced by healthy and neoplastic cells. Its activities are mediated by two receptor tyrosine kinases. VEGF signaling is often a rate-limiting step in physiologic and pathologic angiogenesis. Bevacizumab has been studied as an antiangiogenic cancer therapeutic as a single agent and in combination with chemotherapy in patients with stage III and IV colon cancer. In addition to its direct antiangiogenic effects, bevacizumab may allow more efficient delivery of chemotherapy by altering tumor vasculature and decreasing the elevated interstitial pressure common in tumors. In this regard, some of the most robust phase II data using bevacizumab are from a randomized study of chemotherapy [fluorouracil (5-FU) and leucovorin (LV)] with or without bevacizumab in metastatic colorectal cancer. In this study, treatment with bevacizumab plus 5-FU/LV resulted in higher response rates, longer median time to disease progression, and longer median survival. Recently, a phase III, multicenter, double-blind, randomized, placebo-controlled trial was designed to investigate the addition of bevacizumab to first-line irinotecan, 5-FU, and LV chemotherapy (IFL). The trial showed a higher response rate, longer time to tumor progression, and prolonged overall survival in patients with metastatic colorectal cancer. It was the first large, randomized, phase III survival trial to assess the importance of targeting VEGF and tumor angiogenesis for the treatment of human cancer. Integration of novel agents targeting VEGF and EGFR with irinotecan-based chemotherapy has shown clinical activity in patients with metastatic colorectal cancer. The goal in the future will be to predict which specific chemotherapy and targeted agent combination will most likely benefit individual patients.

Antibodies, Monoclonal↗

Incorporating prior beliefs about selection bias into the analysis of randomized trials with missing outcomes.

In randomized studies with missing outcomes, non-identifiable assumptions are required to hold for valid data analysis. As a result, statisticians have been advocating the use of sensitivity analysis to evaluate the effect of varying assumptions on study conclusions. While this approach may be useful in assessing the sensitivity of treatment comparisons to missing data assumptions, it may be dissatisfying to some researchers/decision makers because a single summary is not provided. In this paper, we present a fully Bayesian methodology that allows the investigator to draw a 'single' conclusion by formally incorporating prior beliefs about non-identifiable, yet interpretable, selection bias parameters. Our Bayesian model provides robustness to prior specification of the distributional form of the continuous outcomes.

Acquired Immunodeficiency Syndrome↗

Consumption of sweet, salty, sour, and bitter solutions by selectively bred alcohol-preferring and alcohol-nonpreferring lines of rats.

To determine whether selective breeding for high or low oral ethanol consumption is associated with different preferences for nonpharmacological solutions with various flavors, the oral intake of a range of concentrations of sucrose (0.5-64.0 g/100 ml), NaCl (0.025-3.2 g/100 ml), citric acid (0.008-2.048 g/liter), and sucrose octaacetate (0.002-0.512 g/liter) was studied in alcohol-preferring (P) and alcohol-nonpreferring (NP) rats. Separate groups of 7-8 rats from each line were tested for consumption of each of the four flavors. The flavored solutions were presented continuously with water and food always available, and the concentrations were doubled every 48 hr. Although rats from both lines showed a strong preference for the sucrose solutions, P rats consumed greater amounts than NP rats [F(7,98) = 5.57, p < 0.001]. Rats of the P line drank less of the NaCl solutions than NP rats [F(7,98) = 3.88, p < 0.001], but the effect was not as robust as the line differences seen with sucrose. The P and NP rats did not differ in citric acid or sucrose octaacetate intake at any of the concentrations tested. Selective breeding for high oral ethanol preference appears to be positively associated with consumption of sweet solutions and negatively associated with intake of salty solutions.

Alcohol Drinking↗

Engineering Streptomyces clavuligerus deacetoxycephalosporin C synthase for optimal ring expansion activity toward penicillin G.

The deacetoxycephalosporin C synthase (DAOCS) from Streptomyces clavuligerus was engineered with the aim of enhancing the conversion of penicillin G into phenylacetyl-7-aminodeacetoxycephalosporanic acid, a precursor of 7-aminodeacetoxycephalosporanic acid, for industrial application. A single round of random mutagenesis followed by the screening of 5,500 clones identified three mutants, G79E, V275I, and C281Y, that showed a two- to sixfold increase in the k(cat)/K(m) ratio compared to the wild-type enzyme. Site-directed mutagenesis to modify residues surrounding the substrate resulted in three mutants, N304K, I305L, and I305M, with 6- to 14-fold-increased k(cat)/K(m) values. When mutants containing all possible combinations of these six sites were generated to optimize the ring expansion activity for penicillin G, the double mutant, YS67 (V275I, I305M), showed a significant 32-fold increase in the k(cat)/K(m) ratio and a 5-fold increase in relative activity for penicillin G, while the triple mutant, YS81 (V275I, C281Y, I305M), showed an even greater 13-fold increase in relative activity toward penicillin G. Our results demonstrate that this is a robust approach to the modification of DAOCS for an optimized DAOCS-penicillin G reaction.

Amino Acid Substitution↗

DNA helicase Srs2 disrupts the Rad51 presynaptic filament.

Mutations in the Saccharomyces cerevisiae gene SRS2 result in the yeast's sensitivity to genotoxic agents, failure to recover or adapt from DNA damage checkpoint-mediated cell cycle arrest, slow growth, chromosome loss, and hyper-recombination. Furthermore, double mutant strains, with mutations in DNA helicase genes SRS2 and SGS1, show low viability that can be overcome by inactivating recombination, implying that untimely recombination is the cause of growth impairment. Here we clarify the role of SRS2 in recombination modulation by purifying its encoded product and examining its interactions with the Rad51 recombinase. Srs2 has a robust ATPase activity that is dependent on single-stranded DNA (ssDNA) and binds Rad51, but the addition of a catalytic quantity of Srs2 to Rad51-mediated recombination reactions causes severe inhibition of these reactions. We show that Srs2 acts by dislodging Rad51 from ssDNA. Thus, the attenuation of recombination efficiency by Srs2 stems primarily from its ability to dismantle the Rad51 presynaptic filament efficiently. Our findings have implications for the basis of Bloom's and Werner's syndromes, which are caused by mutations in DNA helicases and are characterized by increased frequencies of recombination and a predisposition to cancers and accelerated ageing.

Adenosine Triphosphatases↗

Fatality in mice due to oversaturation of cellular microRNA/short hairpin RNA pathways.

RNA interference (RNAi) is a universal and evolutionarily conserved phenomenon of post-transcriptional gene silencing by means of sequence-specific mRNA degradation, triggered by small double-stranded RNAs. Because this mechanism can be efficiently induced in vivo by expressing target-complementary short hairpin RNA (shRNA) from non-viral and viral vectors, RNAi is attractive for functional genomics and human therapeutics. Here we systematically investigate the long-term effects of sustained high-level shRNA expression in livers of adult mice. Robust shRNA expression in all the hepatocytes after intravenous infusion was achieved with an optimized shRNA delivery vector based on duplex-DNA-containing adeno-associated virus type 8 (AAV8). An evaluation of 49 distinct AAV/shRNA vectors, unique in length and sequence and directed against six targets, showed that 36 resulted in dose-dependent liver injury, with 23 ultimately causing death. Morbidity was associated with the downregulation of liver-derived microRNAs (miRNAs), indicating possible competition of the latter with shRNAs for limiting cellular factors required for the processing of various small RNAs. In vitro and in vivo shRNA transfection studies implied that one such factor, shared by the shRNA/miRNA pathways and readily saturated, is the nuclear karyopherin exportin-5. Our findings have fundamental consequences for future RNAi-based strategies in animals and humans, because controlling intracellular shRNA expression levels will be imperative. However, the risk of oversaturating endogenous small RNA pathways can be minimized by optimizing shRNA dose and sequence, as exemplified here by our report of persistent and therapeutic RNAi against human hepatitis B virus in vivo.

Animals↗

Evolution and phylogeny of the Diptera: a molecular phylogenetic analysis using 28S rDNA sequences.

Portions of the large ribosomal subunit RNA gene (28S rDNA) encompassing the D1 and the D7 region were obtained from 16 dipteran species and families to reconstruct early phylogenetic events in the order Diptera. For outgroup comparison, the corresponding sequences were used from representative taxa of the Siphonaptera, Mecoptera, and Lepidoptera. A subset of 488 unambiguously alignable sites was analyzed with respect to important sequence evolution parameters. We found (1) sequence variability is significantly higher in double-stranded sites than in single-stranded sites, (2) transitions are close to saturation in most pairwise sequence comparisons, (3) significant substitution rate heterogeneity exists across sites, and (4) significant substitution rate heterogeneity exists among lineages. Tree reconstruction was carried out with the neighbor joining, maximum parsimony, and maximum likelihood methods. Four major subgroups are consistently and robustly supported: the Brachycera, the Culicomorpha, the Tipulomorpha sensu stricto, and the hitherto controversial Bibionomorpha sensu lato, which includes the families Sciaridae, Mycetophilidae, Cecidomyiidae, Bibionidae, Scatopsidae, and Anisopodidae. The phylogenetic relationships within or among these subclades and the positions of the families Psychodidae and Trichoceridae were not robustly resolved. These results support the view that the mouthparts of extant dipteran larvae evolved from a derived ground state characterized by subdivided and obliquely moving mandibles. Furthermore, sequence divergence and the paleontological record consistently indicate that a period of rapid cladogenesis gave rise to the major dipteran subgroups.

Animals↗

Two-dimensional noise-robust blind deconvolution of ultrasound images.

This paper presents a new method for 2-D blind homomorphic deconvolution of medical B-scan ultrasound images. The method is based on noise-robust 2-D phase unwrapping and a noise-robust procedure to estimate the pulse in the complex cepstrum domain. Ordinary Wiener filtering is used in the subsequent deconvolution. The resulting images became much sharper with better defined tissue structures compared with the ordinary images. The deconvolved images had a resolution gain along the order of 3 to 7, and the signal-to-noise ratio (SNR) doubled for many of the images used in our experiments. The method gave stable results with respect to noise and grey levels through several image sequences.

Adult↗