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Microtubules (MTs) are the largest type of cellular filament, essential in processes ranging from mitosis and meiosis to flagellar motility. Many of the processes depend critically on the mechanical properties of the MT, but the elastic moduli, notably the Young's modulus, are not directly revealed in experiment, which instead measures either flexural rigidity or response to radial deformation. Molecular dynamics (MD) is a method that allows the mechanical properties of single biomolecules to be investigated through computation. Typically, MD requires an atomic resolution structure of the molecule, which is unavailable for many systems, including MTs. By combining structural information from cryo-electron microscopy and electron crystallography, we have constructed an all-atom model of a complete MT and used MD to determine its mechanical properties. The simulations revealed nonlinear axial stress-strain behavior featuring a pronounced softening under extension, a possible plastic deformation transition under radial compression, and a distinct asymmetry in response to the two senses of twist. This work demonstrates the possibility of combining different levels of structural information to produce all-atom models suitable for quantitative MD simulations, which extends the range of systems amenable to the MD method and should enable exciting advances in our microscopic knowledge of biology.

Background.Multidisciplinary antimicrobial utilization teams (AUTs) have been proposed as a mechanism for improving antimicrobial use, but data on their efficacy remain limited.Objective.To determine the impact of an AUT on antimicrobial use at a teaching hospital.Design.Randomized controlled intervention trial.Setting.A 953-bed, public, university-affiliated, urban teaching hospital.Patients.Patients who were given selected antimicrobial agents (piperacillin-tazobactam, levofloxacin, or vancomycin) by internal medicine ward teams.Intervention.Twelve internal medicine teams were randomly assigned monthly: 6 teams to an intervention group (academic detailing by the AUT) and 6 teams to a control group that was given indication-based guidelines for prescription of broad-spectrum antimicrobials (standard of care), during a 10-month study period.Measurements.Proportion of appropriate empirical, definitive (therapeutic), and end (overall) antimicrobial usage.Results.A total of 784 new prescriptions of piperacillin-tazobactam, levofloxacin, and vancomycin were reviewed. The proportion of antimicrobial prescriptions written by the intervention teams that was considered to be appropriate was significantly higher than the proportion of antimicrobial prescriptions written by the control teams that was considered to be appropriate: 82% versus 73% for empirical (risk ratio [RR], 1.14; 95% confidence interval [CI], 1.04-1.24), 82% versus 43% for definitive (RR, 1.89; 95% CI, 1.53-2.33), and 94% versus 70% for end antimicrobial usage (RR, 1.34; 95% CI, 1.25-1.43). In multivariate analysis, teams that received feedback from the AUT alone (adjusted RR, 1.37; 95% CI, 1.27-1.48) or from both the AUT and the infectious diseases consultation service (adjusted RR, 2.28; 95% CI, 1.64-3.19) were significantiy more likely to prescribe end antimicrobial usage appropriately, compared with control teams.Conclusions.A multidisciplinary AUT that provides feedback to prescribing physicians was an effective method in improving antimicrobial use.Trial Registration.ClinicalTrials.gov identifier: NCT00552838.

Functional proteins of complex eukaryotes within the same species are rather invariant. A single catalytic component of telomerase TERTis essential for an active telomerase complex that maintains telomeres. Surprisingly, we have identified two paralogous SpTERT-Land SpTERT-Sgenes with novel domains in Strongylocentrotus purpuratus(purple sea urchin). The SpTERT-Sand SpTERT-Lgenes were differentially expressed throughout embryogenesis. An unusual germline nucleotide substitution and amino acid variation was evident in these TERTs. The hypervariability of SpTERT-Shaplotypes among different individuals reached unprecedented levels of π > 0.2 in exon 11 region. The majority of nucleotide changes observed led to nonsynonymous substitutions creating novel amino acids and motifs, suggesting unusual positive selection and rapid evolution. The majority of these variations were in domains involved in binding of SpTERTto its RNA component. Despite hypervariability at protein level, SpTERT-Sconferred telomerase activity, and its suppression during early embryogenesis led to arrest at late mesenchymal blastula. Domain exchange and embryo rescue experiments suggested that SpTERTmay have evolved functions unrelated to classic telomerase activity. We suggest that telomerase has a specific and direct function that is essential for integration of early polarity signals that lead to gastrulation. Identification of these unique hypervariable telomerases also suggests presence of a diversity generation mechanism that inculcates hypervariable telomerases and telomere lengths in germline.

SIRT1, the mammalian homolog of SIR2 in Saccharomyces cerevisiae, is an NAD-dependent deacetylase implicated in regulation of lifespan. By designing effective short hairpin RNAs and a silent shRNA-resistant mutant SIRT1 in a genetically defined system, we show that efficient inhibition of SIRT1 in telomerase-immortalized human cells enhanced cell growth under normal and nutrient limiting conditions. Hematopoietic stem cells obtained from SIRT1-deficient mice also showed increased growth capacity and decreased dependency on growth factors. Consistent with this, SIRT1 inhibition was associated with increased telomerase activity in human cells. We also observed a significant increase in AMPK levels up on SIRT1 inhibition under glucose limiting conditions. Although SIRT1 suppression cooperated with hTERT to promote cell growth, either overexpression or suppression of SIRT1 alone had no effect on life span of human diploid fibroblasts. Our findings challenge certain models and connect nutrient sensing enzymes to the immortalization process. Furthermore, they show that in certain cell lineages, SIRT1 can act as a growth suppressor gene.

Short-term quality improvement (QI) interventions for depression can improve long-term mental health but mechanisms are unknown. We hypothesized that 1 pathway for such health benefits was an indirect effect with QI reducing risk factors for depression such as stressful life events.

Quality improvement (QI) programs for depression can improve outcomes of care and reduce outcome disparities; but cumulative effects on mental health outcome disparities have seldom been evaluated.

Background: Multidrug-resistant Acinetobacter baumannii (MDR-Ab) has emerged as an increasingly problematic cause of hospital-acquired infections in the intensive care unit (ICU). MDR-Ab is resistant to most standard antimicrobials but often retains susceptibility to polymyxin B and doxycycline.Objective: To evaluate the efficacy and toxicity of polymyxin B and doxycycline in the treatment of MDR-Ab infections.Methods: A retrospective chart review was conducted between March 2002 and May 2005 in patients who received doxycycline or polymyxin B for treatment of MDR-Ab infections in ICUs within Grady Memorial Hospital, Atlanta, GA.Results: Thirty-seven patients with MDR-Ab infections were treated with polymyxin B or doxycycline. Median age was 41 years and median ICU length of stay was 18 days prior to acquisition of MDR-Ab. Clinical cure was observed in 22 of 29 (76%) evaluable patients treated with polymyxin B and 2 of 4 (50%) patients treated with doxycycline. In patients with follow-up cultures, microbiological cure was observed in 17 of 21 (81%) patients treated with polymyxin B and 2 of 3 (67%) patients treated with doxycycline. Nephrotoxicity developed in 21% (7 of 33) of patients who received polymyxin B. Neurotoxicity was observed in 2 (6%) patients who received polymyxin B. No adverse reactions were observed with doxycycline. Overall, crude mortality was 27% (9 of 33) and 75% (3 of 4) among those who received polymyxin B and doxycycline, respectively. Three (9%) deaths were attributed to polymyxin B treatment failure, and no deaths were attributed to doxycycline treatment failure.Conclusions: Polymyxin B was effectively used to treat a substantial proportion of critically ill patients with MDR-Ab infection and was associated with a similar rate of nephrotoxicity as previously reported. Doxycycline monotherapy was used in a limited number of patients for the treatment of MDR-Ab; further evaluation of its efficacy in larger numbers of patients is warranted.

We investigated knowledge, attitudes, and behaviors of prescribers concerning piperacillin-tazobactam use at 4 Emory University-affiliated hospitals. Discussions during focus groups indicated that the participants' perceived knowledge of clinical criteria for appropriate piperacillin-tazobactam use was inadequate. Retrospective review of medical records identified inappropriate practices. These findings have influenced ongoing interventions aimed at optimizing piperacillin-tazobactam use.

Proteins secreted by Neisseria meningitidis are thought to play important roles in the pathogenesis of meningococcal disease. These proteins include the iron-repressible repeat-in-toxin (RTX) exoprotein FrpC. Related proteins in other pathogens are secreted via a type I secretion system (TOSS), but such a system has not been demonstrated in N. meningitidis. An in silico search of the group B meningococcal genome suggested the presence of a uniquely organized TOSS. Genes encoding homologs of the Escherichia coli HlyB (ATP-binding), HlyD (membrane fusion), and TolC (outer membrane channel) proteins were identified. In contrast to the cistronic organization of the secretion genes in most other rtx operons, the hlyD and tolC genes were adjacent but unlinked to hlyB; neither locus was part of an operon containing genes encoding putative TOSS substrates. Both loci were flanked by genes normally associated with mobile genetic elements. The three genes were shown to be expressed independently. Mutation at either locus resulted in an inability to secrete FrpC and a related protein, here called FrpC2. Successful complementation of these mutations at an ectopic site confirmed the observed phenotypes were caused by loss of function of the putative TOSS genes. We show that genes scattered in the meningococcal genome encode a functional TOSS required for secretion of the meningococcal RTX proteins.

In recognition of the need for immunological memory-inducing components for future Neisseria meningitidis group B vaccines, we previously searched the proteome of N. meningitidis and identified T-cell-stimulating protein A (TspA). This study was designed to confirm the immunogencity of TspA and to examine the subset of T-helper cell responses to the protein in patients and nasopharyngeal carriers. The tspA gene was reconstructed, cloned, and expressed in Escherichia coli, and the recombinant TspA (rTspA) protein was affinity purified. T-cell proliferative responses to rTspA were detected in the peripheral blood mononuclear cells (PBMCs) of convalescent patients and carriers, confirming that TspA-specific T-cell responses were stimulated by invasive disease and nasopharyngeal colonization. Following stimulation of PBMCs with meningococcal lysate, increased frequencies of both Th1 and Th2 cells were observed, indicating that, as during carriage, invasive meningococcal disease induced an unbiased T-helper subset response. A similar unbiased T-helper response was also detected against rTspA in the PBMCs of convalescent patients. The response of PBMCs from the carriers to TspA stimulation, however, was very weak, and the frequencies of cytokine-positive CD4 cells were not significantly greater than the frequencies in unstimulated control cultures. All of the patients and carriers responded with serum antimeningococcal immunoglobulin G (IgG) antibodies, while four of six samples from patients and 5 of 14 samples from carriers contained detectable anti-rTspA IgG antibodies. Taken together, the results of this study confirmed the immunogenicity of TspA in humans during natural meningococcal infection, and therefore, TspA is worthy of further investigation as a possible T-cell stimulating component of future vaccines.

The short story "Lap Dance" by D. B. Wells is presented.

Deprotonation of chiral complexes of the type Tp‘(CO)(I)W{RC&tbd1;CCH2R‘} at the propargyl carbon followed by alkylation is regioselective and stereoselective. Photolysis liberates the elaborated alkynes from the metal complex. Resolution of metal diastereomers, with amido ligands, Tp‘(CO)(NHR)W{CH3C&tbd1;CCH3} (NH2R = ((S)-(−)-α-methylbenzylamine), has been accomplished by fractional crystallization. Conversion to an amine complex followed by iodide replacement of H2NCHMePh produces separate enantiomers of Tp‘(CO)(I)W{CH3C&tbd1;CCH3}. Methylation followed by benzylation of each enantiomer affords Tp‘(CO)(I)W{CH3C&tbd1;CCHMeCH2Ph}. The alkynes (−)-CH3C&tbd1;CCHMeCH2Ph and (+)-CH3C&tbd1;CCHMeCH2Ph have been released from each of these enantiomerically enriched complexes in optically active form, as assayed by optical rotation and by ¹H NMR with chiral shift reagents. The barrier to alkyne rotation in Tp‘(CO)(I)W{RC&tbd1;CCH2R‘} complexes has been probed by variable-temperature ¹H NMR, and extended Huckel molecular orbital calculations have been performed on model complexes. The origin of regioselectivity and stereoselectivity is considered in light of the X-ray structures of Tp‘(CO)(I)W{CH3C&tbd1;CCHMe(CH2)4I} (7) and Tp‘(CO)(I)W{Me(PhCH2)HCC&tbd1;CCHMeCH(OH)Ph} (11). The absolute configuration of Tp‘(CO)W{CH3C&tbd1;CCH3}(NHCHMePh) ((+)-14(SS)) has been established by X-ray analysis with the resolving amine as reference.

We present λCIL, a typed λ-calculus which serves as the foundation for a typed intermediate language for optimizing compilers for higher-order polymorphic programming languages. The key innovation of λCIL is a novel formulation of intersection and union types and flow labels on both terms and types. These flow types can encode polyvariant control and data flow information within a polymorphically typed program representation. Flow types can guide a compiler in generating customized data representations in a strongly typed setting. Since λCIL enjoys confluence, standardization, and subject reduction properties, it is a valuable tool for reasoning about programs and program transformations.

Objectives: The purpose of this investigation was to assess the relationship of primary care specialty training with self-assessed skill, knowledge, attitudes, and behavior toward depression recognition and management.Method: A baseline self-report questionnaire was administered to 184 internists and 138 family physicians participating in a multisite depression intervention study.Results: There were no marked differences in knowledge of internists and family physicians regarding depression, in attitudes about the effectiveness of specific therapies, or in barriers to providing optimum treatment for depression. However, compared to internists, family physicians rated themselves as more skilled in the management of depression. When considering management of patients with moderate to severe depression, family physicians were more likely to report that they prescribed a selective serotonin-reuptake inhibitor (relative odds (RO) = 3.51, 95 percent Confidence interval (CI) [2.19, 5.60] and to personally counsel patients (RO = 1.97, 95 percent CI [1.16, 3.38]) more than half the patients, but were less likely to refer to a specialist in mental health (RO = 0.52, 95 percent CI [0.33, 0.82]) than were internists. Additional potentially influential characteristics did not wholly account for the reported differences in practice according to specialty. Physicians of both specialties expressed considerable uncertainty in their knowledge of psychotherapy and in their evaluation of the effectiveness of other strategies for the prevention of recurrence of depression.Conclusion: Strategies to improve mental health care should account for the orientation of primary care physicians to mental health issues.

This study identifies characteristics associated with problem substance use among 1,187 patients with either depressive symptoms (44%) or depressive disorders (56%) in primary care clinics of six managed care organizations. Sedative misuse (reported by 14% of all patients) was associated with greater wealth, social phobia, and misuse of prescription opioids. Cannabis use (11%) was associated with younger age, male gender, single marital status, white ethnicity, less education, recurrent depression, agoraphobia, and hazardous alcohol use. Hazardous drinking (11%) was significantly associated with younger age, male gender, single marital status, and cannabis use. Greater understanding of substance use problems in primary care patients with depressive symptoms and disorders may aid efforts to more quickly identify, educate, and provide services for those in need.

Utility methods that are responsive to changes in desirable outcomes are needed for cost-effectiveness (CE) analyses and to help in decisions about resource allocation.

Continuity of the relationship between patients and primary care providers (PCPs) is an important component of care from the consumer perspective that may be affected by variation in cost containment strategies within managed care.

Depression is common in primary care, but rates of adequate care are low. Little is known about the role of patient treatment preferences in encouraging entry into care.