Late thrombosis in drug-eluting coronary stents after discontinuation of antiplatelet therapy

Although the safety profiles of coronary stents eluting sirolimus or paclitaxel do not seem to differ from those of bare metal stents in the short-to-medium term, concern has arisen about the potential for late stent thromboses related to delayed endothelialisation of the stent struts. We report four cases of angiographically-confirmed stent thrombosis that occurred late after elective implantation of polymer-based paxlitaxel-eluting (343 and 442 days) or sirolimus-eluting (335 and 375 days) stents, and resulted in myocardial infarction. All cases arose soon after antiplatelet therapy was interrupted. If confirmed in systematic long-term follow-up studies, our findings have potentially serious clinical implications.     

Cross-sectional and longitudinal association between antihypertensive medications and cognitive impairment in an elderly population

BACKGROUND: The effect of antihypertensive medications on cognitive function has not been well studied. The authors' objectives were to investigate the cross-sectional and longitudinal association between the use of antihypertensive medications and cognitive function and to compare different antihypertensive medication classes with regard to this association in an elderly population. METHODS: The medical records of a convenience sample of patients (n = 993 cross-sectional and 350 longitudinal; mean age, 76.8 +/- 0.3 years; 74% women; 87% White) followed at a geriatric practice were reviewed. Data abstracted included demographics, medical history (Alzheimer's disease [AD] or vascular dementia [VaD]), use of antihypertensive medications, and results of cognitive assessments (the Mini-Mental Status Examination [MMSE] and the Clock Draw Test [CDT]). RESULTS: In the cross-sectional analysis, antihypertensive use was not associated with MMSE (p >.05), CDT (p >.05), or dementia diagnosis (odds ratio for AD, 0.8; 95% confidence interval [CI], 0.6 to 1.2; odds ratio for VaD, 1.6; 95% CI, 0.6 to 4.0). In the longitudinal analysis, antihypertensive use was associated with a lower rate of cognitive decline on the MMSE (-0.8 +/- 2 points in users vs -5.8 +/- 2.5 points in nonusers; p =.007) and on the CDT (-0.3 +/- 0.8 points in users vs -2.2 +/- 0.8 points in nonusers; p =.002), and with a lower risk for the development of cognitive impairment (odds ratio, 0.56; 95% CI, 0.38 to 0.83; p =.004). The trend was similar in patients with baseline AD (p =.02). Patients taking diuretics (p =.007), angiotensin-converting enzyme inhibitors (p =.016), and beta-blockers (p =.014) had a lower rate of cognitive decline, and patients taking angiotensin receptor blockers (p =.016) had improved cognitive scores. CONCLUSIONS: Antihypertensive use, particularly diuretics, angiotensin-converting enzymes inhibitors, beta-blockers, and angiotensin receptor blockers, may be associated with a lower rate of cognitive decline in older adults, including those with AD. Until a randomized clinical trial confirms our results, findings of this observational study should be interpreted with caution.     

Bepridil for chronic stable angina pectoris: Results of a prospective multicenter,placebo-controlled,dose-ranging study in 77 patients

Bepridil, a new calcium-channel blocking agent with an extended plasma elimination half-life of > 50 hours, was compared to placebo in 77 patients with confirmed coronary artery disease and chronic stable angina pectoris. The effects of bepridil were compared with those of placebo on angina frequency, nitroglycerin tablet use, the resting ECG and hemodynamics at rest and maximal exercise using a study design comprising 5 sequential 2-week single-blind treatment phases. After 2 weeks of placebo (phase 1), bepridil was given for 3 phases (2, 3 and 4) at total daily dosages of 200, 300 and 400 mg, respectively; the study was completed after a final reintroduction of placebo (phase 5). Within each phase once- and twice-daily regimens of bepridil were randomly compared.Bepridil (300 mg/day) reduced anginal frequency 68 %, from 8.5 ± 1.1 (standard error of the mean) to 2.7 ± 0.7 attacks/week and nitroglycerin tablet use 76% (p < 0.001). Bepridil improved exercise duration 26 %, from 6.9 ± 0.4 to 8.7 ± 0.5 minutes (p < 0.001) and exercise work 52%, from 2.7 ± 0.3 to 4.1 ± 0.4 kpm × 10^?3 (p < 0.001) on a standardized treadmill protocol. Resting and peak exercise heart rate and blood pressure were unaffected by bepridil. The antianginal effects were similar with either once- or twice-daily treatment schedules. Minor side effects of nausea, epigastric discomfort and tremor were infrequent and there were no major side effects. The results of this large but preliminary, single-blind and short-term study suggest that bepridil is an effective and well tolerated antianginal agent when administered once daily.     

Genome-wide toxicogenomic study of the lanthanides sheds light on the selective toxicity mechanisms associated with critical materials

Lanthanides are a series of critical elements widely used in multiple industries, such as optoelectronics and healthcare. Although initially considered to be of low toxicity, concerns have emerged during the last few decades over their impact on human health. The toxicological profile of these metals, however, has been incompletely characterized, with most studies to date solely focusing on one or two elements within the group. In the current study, we assessed potential toxicity mechanisms in the lanthanide series using a functional toxicogenomics approach in baker’s yeast, which shares many cellular pathways and functions with humans. We screened the homozygous deletion pool of 4,291 Saccharomyces cerevisiae strains with the lanthanides and identified both common and unique functional effects of these metals. Three very different trends were observed within the lanthanide series, where deletions of certain proteins on membranes and organelles had no effect on the cellular response to early lanthanides while inducing yeast sensitivity and resistance to middle and late lanthanides, respectively. Vesicle-mediated transport (primarily endocytosis) was highlighted by both gene ontology and pathway enrichment analyses as one of the main functions disturbed by the majority of the metals. Protein–protein network analysis indicated that yeast response to lanthanides relied on proteins that participate in regulatory paths used for calcium (and other biologically relevant cations), and lanthanide toxicity included disruption of biosynthetic pathways by enzyme inhibition. Last, multiple genes and proteins identified in the network analysis have human orthologs, suggesting that those may also be targeted by lanthanides in humans.

Since their discovery, lanthanides have presented both difficulty and opportunity for researchers. As a series, these elements behave rather similarly: most of them form +3 ions in aqueous solution (1), prefer highly electronegative anionic ligands (2), and form insoluble hydroxide precipitates at neutral pH if not otherwise complexed (3). Although the chemical similarities between these elements made their initial isolation and characterization a significant challenge, they now have unique applications in industry and medicine. Several lanthanides have become critical materials for many clean and sustainable energy technologies that will drive the future of our societies and are used, for example, in the production of batteries, magnets, motors, and other electronic components (4); low-concentration mixtures of lanthanides are used in Chinese agriculture to increase body weight gain among livestock (5, 6); lanthanum carbonate (sold under the commercial name of Fosrenol) is a noncalcium phosphate binder used to control hyperphosphataemia (7); and gadolinium is employed in diagnostic medicine, as an essential component of MRI contrast agents (8, 9).The growing use of lanthanides has increased the potential for human exposure to large concentrations of these metals, requiring more detailed investigations into their toxicological properties. For instance, administration of gadolinium-based contrast agents has been associated with the development of nephrogenic systemic fibrosis in patients with compromised renal function (10–12). Moreover, accumulation of gadolinium in the brains of patients who received repeated doses of gadolinium-based contrast agents has also been reported (13). Despite the current ubiquity of lanthanides, their toxicological profile has been incompletely characterized because until recently they were considered to be of low toxicological concern (14, 15). Previous toxicity studies primarily focused on lanthanum or cerium (and, to a lesser extent, neodymium and gadolinium), with the notion that these metals were representative of the series (14, 16–18). However, to our knowledge, no comprehensive mechanistic assay has been conducted to evaluate metal toxicity across the series, and little is known about what toxicological mechanisms may be shared by the different lanthanides.Saccharomyces cerevisiae is one of the best-characterized model organisms (19, 20), and there are many tools available for analyzing its genomic data (21–23). For example, yeast functional toxicogenomic screening is a powerful tool for investigating cellular mechanisms of cytotoxicity (24, 25). This method makes use of the yeast deletion libraries generated by the Yeast Deletion Project (26), a consortium of researchers across the United States and Canada, to establish relationships between genes and chemical exposures. Researchers used heterozygous and homozygous deletion pools of barcoded yeast strains to derive mechanistic toxicological information about a wide array of chemicals, pharmaceuticals, metals, and biological compounds (27, 28). As eukaryotes, yeast and humans share many cellular pathways and functions, and many components of cell biology identified in S. cerevisiae have homologs in human biology (29–31). Consequently, functional toxicogenomic screening offers unique opportunities to evaluate the mechanisms of cytotoxicity and general biological activity across the lanthanide series in yeast and explore potentially conserved mechanisms in humans.Here, we identify fundamental cellular functions disrupted by lanthanides using functional toxicogenomics in S. cerevisiae. The metals studied had distinct behaviors: early lanthanides showed limited unique functional effects, while middle and late lanthanides had prominent and distinct ones. Although the functional effects of each lanthanide were different and suggested some very efficient element discrimination by endogenous molecules, we observed a few common trends. In particular, vesicle-mediated transport (primarily endocytosis) was perturbed by the majority of the lanthanides tested. Moreover, protein–protein network analysis suggested that lanthanides mimic calcium ions, interacting with calcium-binding proteins and disrupting processes regulated by this cation. Finally, several of the highly interconnected proteins targeted by multiple lanthanides in the network analysis are conserved in humans, suggesting their roles in the origin of the human health issues associated with lanthanide exposure and opening many directions for the determination of mechanisms associated with toxicity.     

A systematic review and meta-analysis of the prevalence of small fiber pathology in fibromyalgia: Implications for a new paradigm in fibromyalgia etiopathogenesis

Objectives

Fibromyalgia is a condition which exhibits chronic widespread pain with neuropathic pain features and has a major impact on health-related quality of life. The pathophysiology remains unclear, however, there is increasing evidence for involvement of the peripheral nervous system with a high prevalence of small fiber pathology (SFP). The aim of this systematic literature review is to establish the prevalence of SFP in fibromyalgia.

Characterization of the requirements for localization of phytochrome B to nuclear bodies

Phytochromes are red- and far-red-sensing photoreceptors that detect the quantity, quality, and duration of light throughout the entire life cycle of plants. Phytochromes accumulate in the cytoplasm in the dark. As one of the earliest responses after light illumination, phytochromes localize to the nucleus where they become associated with discrete nuclear bodies (NBs). Here, we describe the steady-state dynamics of Arabidopsis phytochrome B (phyB) localization in response to different light conditions and define four phyB subnuclear localization patterns: diffuse nuclear localization, small and numerous NBs only, both small and large NBs, and large NBs only. We show that phyB nuclear import is not sufficient for phyB NB formation. Rather, phyB accumulation in NBs is mainly determined by the percentage of the total amount of phyB protein that is in the active phyB conformer, with large NBs always correlating with strong phyB responses. A genetic screen to identify determinants required for subnuclear localization of phyB resulted in several phyB mutants, mutants deficient in phytochrome chromophore biosynthesis, and mutations in at least one previously uninvestigated locus. This study lays the groundwork for future investigations to identify the molecular mechanisms of light-regulated partitioning of plant photoreceptors to discrete subnuclear domains.     

Collaborative signaling by mixed chemoreceptor teams in Escherichia coli

Chemoreceptors of the methyl-accepting chemotaxis protein family form clusters, typically at the cell pole(s), in both Bacteria and Archaea. To elucidate the architecture and signaling role of receptor clusters, we investigated interactions between the serine (Tsr) and aspartate (Tar) chemoreceptors in Escherichia coli by constructing Tsr mutations at the six hydrophobic and five polar residues implicated in "trimer of dimers" formation. Tsr mutants with proline replacements could not mediate serine chemotaxis, receptor clustering, or clockwise flagellar rotation. Alanine and tryptophan mutants, although also nonchemotactic, formed receptor clusters, and some produced clockwise flagellar rotation, indicating receptor-coupled activation of the signaling CheA kinase. The alanine and tryptophan mutants evidently assemble defective receptor complexes that cannot modulate CheA activity in response to serine stimuli. In cells containing wild-type Tar receptors, tryptophan replacements in Tsr interfered with Tar function, whereas four Tsr mutants with alanine replacements regained Tsr function. These epistatic and rescuable phenotypes imply interactions between Tsr and Tar dimers in higher-order signaling teams. The bulky side chain in tryptophan mutants may prevent stimulus-induced conformational changes in the team, whereas the small side chain in alanine mutants may permit signaling control when teamed with functional receptor molecules. Direct physical interactions between Tsr and Tar molecules were observed by in vivo chemical crosslinking. Wild-type Tsr crosslinked to Tar, whereas a clustering-defective proline replacement mutant did not. These findings indicate that bacterial chemoreceptor clusters are comprised of signaling teams, seemingly based on trimers of dimers, that can contain different receptor types acting collaboratively.     

The combination of the farnesyl transferase inhibitor lonafarnib and the proteasome inhibitor bortezomib induces synergistic apoptosis in human myeloma cells that is associated with down-regulation of p-AKT

The identification of signaling pathways critical to myeloma growth and progression has yielded an array of novel agents with clinical activity. Multiple myeloma (MM) growth is IL-6 dependent, and IL-6 is secreted in an autocrine/paracrine fashion with signaling via the Ras/Raf/mitogen-activated protein kinase (MAPK) pathway. We hypothesized that combining a Ras pathway inhibitor (lonafarnib, SCH66336) with a proteasome inhibitor (bortezomib, Velcade, PS-341) would enhance myeloma-cell killing. MM cell lines and primary human cells were used to test either single agent bortezomib, lonafarnib, or the combination on MM signaling and apoptosis. Combination therapy induced synergistic tumor-cell death in MM cell lines and primary MM plasma cells. Cell death was rapid and associated with increased caspase 3, 8, and 9 cleavage and concomitant down-regulation of p-AKT. Down-regulation of p-AKT was seen only in combination therapy and not seen with either single agent. Cells transfected with constitutively active p-AKT, wild-type AKT, or Bcl-2 continued to demonstrate synergistic cell death in response to the combination. The order of addition was critically important, supporting bortezomib followed by lonafarnib as the optimal schedule. The combination of a proteasome inhibitor and farnesyl transferase inhibitor demonstrates synergistic myeloma-cell death and warrants further preclinical and clinical studies.     

Epidemiology and outcomes of ventilator-associated pneumonia in a large US database

OBJECTIVES: To evaluate risk factors for ventilator-associated pneumonia (VAP), as well as its influence on in-hospital mortality, resource utilization, and hospital charges. DESIGN: Retrospective matched cohort study using data from a large US inpatient database. PATIENTS: Patients admitted to an ICU between January 1998 and June 1999 who received mechanical ventilation for > 24 h. MEASUREMENTS: Risk factors for VAP were examined using crude and adjusted odds ratios (AORs). Cases of VAP were matched on duration of mechanical ventilation, severity of illness on admission (predicted mortality), type of admission (medical, surgical, trauma), and age with up to three control subjects. Mortality, resource utilization, and billed hospital charges were then compared between cases and control subjects. RESULTS: Of the 9,080 patients meeting study entry criteria, VAP developed in 842 patients (9.3%). The mean interval between intubation, admission to the ICU, hospital admission, and the identification of VAP was 3.3 days, 4.5 days, and 5.4 days, respectively. Identified independent risk factors for the development of VAP were male gender, trauma admission, and intermediate deciles of underlying illness severity (on admission) [AOR, 1.58, 1.75, and 1.47 to 1.70, respectively]. Patients with VAP were matched with 2,243 control subjects without VAP. Hospital mortality did not differ significantly between cases and matched control subjects (30.5% vs 30.4%, p = 0.713). Nevertheless, patients with VAP had a significantly longer duration of mechanical ventilation (14.3 +/- 15.5 days vs 4.7 +/- 7.0 days, p < 0.001), ICU stay (11.7 +/- 11.0 days vs 5.6 +/- 6.1 days, p < 0.001), and hospital stay (25.5 +/- 22.8 days vs 14.0 +/- 14.6 days, p < 0.001). Development of VAP was also associated with an increase of > $40,000 USD in mean hospital charges per patient ($104,983 USD +/- $91,080 USD vs $63,689 USD+/- $75,030 USD, p < 0.001). CONCLUSIONS: This retrospective matched cohort study, the largest of its kind, demonstrates that VAP is a common nosocomial infection that is associated with poor clinical and economic outcomes. While strategies to prevent the occurrence of VAP may not reduce mortality, they may yield other important benefits to patients, their families, and hospital systems.