Genes and mechanisms related to RNA interference regulate expression of the small temporal RNAs that control C. elegans developmental timing

RNAi is a gene-silencing phenomenon triggered by double-stranded (ds) RNA and involves the generation of 21 to 26 nt RNA segments that guide mRNA destruction. In Caenorhabditis elegans, lin-4 and let-7 encode small temporal RNAs (stRNAs) of 22 nt that regulate stage-specific development. Here we show that inactivation of genes related to RNAi pathway genes, a homolog of Drosophila Dicer (dcr-1), and two homologs of rde-1 (alg-1 and alg-2), cause heterochronic phenotypes similar to lin-4 and let-7 mutations. Further we show that dcr-1, alg-1, and alg-2 are necessary for the maturation and activity of the lin-4 and let-7 stRNAs. Our findings suggest that a common processing machinery generates guide RNAs that mediate both RNAi and endogenous gene regulation.

Guanine-nucleotide-releasing factor hSos1 binds to Grb2 and links receptor tyrosine kinases to Ras signalling

Many of the actions of receptor tyrosine kinases are mediated by the protein Ras, including the activation of various downstream serine/threonine kinases and the stimulation of growth and differentiation. The human protein Grb2 binds to ligand-activated growth factor receptors and downstream effector proteins through its Src-homology (SH) domains SH2 and SH3, respectively, and like its homologue from Caenorhabditis elegans, Sem-5, apparently forms part of a highly conserved pathway by which these receptors can control Ras activity. Here we show that the SH3 domains of Grb2 bind to the carboxy-terminal part of hSos1, the human homologue of the Drosophila guanine-nucleotide-releasing factor for Ras, which is essential for control of Ras activity by epidermal growth factor receptor and sevenless. Moreover, a synthetic 10-amino-acid peptide containing the sequence PPVPPR specifically blocks the interaction. These results indicate that the Grb2/hSos1 complex couples activated EGF receptor to Ras signalling.

Investigation of the electrochemical and electrocatalytic behavior of single-wall carbon nanotube film on a glassy carbon electrode

The electrochemical behavior of a film of single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups was studied extensively on a glassy carbon (GC) electrode. One stable couple corresponding to the redox of the carboxylic acid group, which was supported by XPS and IR experiments, was observed. The electrode process involved four electrons, while the rate-determining step was a one-electron reduction. The SWNT film-modified electrode showed favorable electrocatalytic behavior toward the oxidation of biomolecules such as dopamine, epinephrine, and ascorbic acid.

Effects of different regimens to lower blood pressure on major cardiovascular events in older and younger adults: meta-analysis of randomised trials

OBJECTIVE

To quantify the relative risk reductions achieved with different regimens to lower blood pressure in younger and older adults.

DESIGN

Meta-analyses and meta-regression analyses used to compare the effects on the primary outcome between two age groups (<65 v > or =65 years). Evidence for an interaction between age and the effects of treatment sought by fitting age as a continuous variable and estimating overall effects across trials.

PRIMARY OUTCOME

total major cardiovascular events.

RESULTS

31 trials, with 190 606 participants, were included. The meta-analyses showed no clear difference between age groups in the effects of lowering blood pressure or any difference between the effects of the drug classes on major cardiovascular events (all P> or =0.24). Neither was there any significant interaction between age and treatment when age was fitted as a continuous variable (all P>0.09). The meta-regressions also showed no difference in effects between the two age groups for the outcome of major cardiovascular events (<65 v > or =65; P=0.38).

CONCLUSIONS

Reduction of blood pressure produces benefits in younger (<65 years) and older (> or =65 years) adults, with no strong evidence that protection against major vascular events afforded by different drug classes varies substantially with age.

The function of GRB2 in linking the insulin receptor to Ras signaling pathways

Insulin-induced activation of extracellular signal-regulated kinases [ERKs, also known as mitogen-activated protein (MAP) kinases] is mediated by Ras. Insulin activates Ras primarily by increasing the rate of guanine nucleotide-releasing activity. Here, we show that insulin-induced activation of ERKs was enhanced by stable overexpression of growth factor receptor-bound protein 2 (GRB2) but not by overexpression of GRB2 proteins with point mutations in the Src homology 2 and 3 domains. Moreover, a dominant negative form of Ras (with Ser17 substituted with Asn) blocked insulin-induced activation of ERKs in cells that overexpressed GRB2. GRB2 overexpression led to increased formation of a complex between the guanine nucleotide-releasing factor Sos (the product of the mammalian homolog of son of sevenless gene) and GRB2. In response to insulin stimulation, this complex bound to tyrosine-phosphorylated IRS-1 (insulin receptor substrate-1) and Shc. In contrast to the activated epidermal growth factor receptor that binds the GRB2-Sos complex directly, activation of the insulin receptor results in the interaction of GRB2-Sos with IRS-1 and Shc, thus linking the insulin receptor to Ras signaling pathways.

Limitations in bonding to dentin and experimental strategies to prevent bond degradation

The limited durability of resin-dentin bonds severely compromises the lifetime of tooth-colored restorations. Bond degradation occurs via hydrolysis of suboptimally polymerized hydrophilic resin components and degradation of water-rich, resin-sparse collagen matrices by matrix metalloproteinases (MMPs) and cysteine cathepsins. This review examined data generated over the past three years on five experimental strategies developed by different research groups for extending the longevity of resin-dentin bonds. They include: (1) increasing the degree of conversion and esterase resistance of hydrophilic adhesives; (2) the use of broad-spectrum inhibitors of collagenolytic enzymes, including novel inhibitor functional groups grafted to methacrylate resins monomers to produce anti-MMP adhesives; (3) the use of cross-linking agents for silencing the activities of MMP and cathepsins that irreversibly alter the 3-D structures of their catalytic/allosteric domains; (4) ethanol wet-bonding with hydrophobic resins to completely replace water from the extrafibrillar and intrafibrillar collagen compartments and immobilize the collagenolytic enzymes; and (5) biomimetic remineralization of the water-filled collagen matrix using analogs of matrix proteins to progressively replace water with intrafibrillar and extrafibrillar apatites to exclude exogenous collagenolytic enzymes and fossilize endogenous collagenolytic enzymes. A combination of several of these strategies should result in overcoming the critical barriers to progress currently encountered in dentin bonding.

Rapid and visual detection of 2019 novel coronavirus (SARS-CoV-2) by a reverse transcription loop-mediated isothermal amplification assay

OBJECTIVE

To evaluate a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and compare it with RT-PCR.

METHODS

We designed primers specific to the orf1ab and S genes of SARS-CoV-2. Total viral RNA was extracted using the QIAamp Viral RNA Mini Kit. We optimized the RT-LAMP assay, and evaluated it for its sensitivity and specificity of detection using real-time turbidity monitoring and visual observation.

RESULTS

The primer sets orf1ab-4 and S-123 amplified the genes in the shortest times, the mean (±SD) times were 18 ± 1.32 min and 20 ± 1.80 min, respectively, and 63°C was the optimum reaction temperature. The sensitivities were 2 × 10¹ copies and 2 × 10² copies per reaction with primer sets orf1ab-4 and S-123, respectively. This assay showed no cross-reactivity with 60 other respiratory pathogens. To describe the availability of this method in clinical diagnosis, we collected 130 specimens from patients with clinically suspected SARS-CoV-2 infection. Among them, 58 were confirmed to be positive and 72 were negative by RT-LAMP. The sensitivity was 100% (95% CI 92.3%-100%), specificity 100% (95% CI 93.7%-100%). This assay detected SARS-CoV-2 in a mean (±SD) time of 26.28 ± 4.48 min and the results can be identified with visual observation.

CONCLUSION

These results demonstrate that we developed a rapid, simple, specific and sensitive RT-LAMP assay for SARS-CoV-2 detection among clinical samples. It will be a powerful tool for SARS-CoV-2 identification, and for monitoring suspected patients, close contacts and high-risk groups.

Membrane targeting of the nucleotide exchange factor Sos is sufficient for activating the Ras signaling pathway

Activation of growth factor receptors results in tyrosine autophosphorylation and recruitment of SH2 domain-containing effectors, including Grb2. Grb2 recruitment mediates activation of the Ras nucleotide exchanger Sos by an unknown mechanism. To examine the role of membrane recruitment, we prepared Sos derivatives containing either myristoylation or farnesylation signals. This resulted in plasma membrane targeting of Sos and stimulation of the Ras signaling pathway, including ERK and AP-1 activities leading to oncogenic transformation. Sos derivatives with nonfunctional myristoylation or farnesylation sequences were inactive. Farnesylation of Sos also activated Ras signaling in yeast. In both mammalian cells and yeast, membrane-targeted Sos derivatives lacking the C-terminal region were considerably more active. Therefore, targeting of Sos to the plasma membrane in the vicinity of Ras appears to be the primary mechanism leading to activation of the Ras pathway. A secondary mechanism could involve relief of the inhibitory effect of the Sos C-terminal region.

Point mutation in FGF receptor eliminates phosphatidylinositol hydrolysis without affecting mitogenesis

Stimulation of growth factor receptors with tyrosine kinase activity is followed by rapid receptor dimerization, tyrosine autophosphorylation and phosphorylation of signalling molecules such as phospholipase C gamma (PLC gamma) and the ras GTPase-activating protein. PLC gamma and GTPase-activating protein bind to specific tyrosine-phosphorylated regions in growth factor receptors through their src-homologous SH2 domains. Growth factor-induced tyrosine phosphorylation of PLC gamma is essential for stimulation of phosphatidylinositol hydrolysis in vitro and in vivo. We have shown that a short phosphorylated peptide containing tyrosine at position 766 from a conserved region of the fibroblast growth factor (FGF) receptor is a binding site for the SH2 domain of PLC gamma (ref. 8). Here we show that an FGF receptor point mutant in which Tyr 766 is replaced by a phenylalanine residue (Y766F) is unable to associate with and tyrosine-phosphorylate PLC gamma or to stimulate hydrolysis of phosphatidylinositol. Nevertheless, the Y766F FGF receptor mutant can be autophosphorylated, and can phosphorylate several cellular proteins and stimulate DNA synthesis. Our data show that phosphorylation of the conserved Tyr 766 of the FGF receptor is essential for phosphorylation of PLC gamma and for hydrolysis of phosphatidylinositol, but that elimination of this hydrolysis does not affect FGF-induced mitogenesis.

Ionizing radiation and short wavelength UV activate NF-kappaB through two distinct mechanisms

We examined the mechanisms by which two different types of photonic radiation, short wavelength UV (UV-C) and gamma radiation, activate transcription factor NF-kappaB. Exposure of mammalian cells to either form of radiation resulted in induction with similar kinetics of NF-kappaB DNA binding activity, nuclear translocation of its p65(RelA) subunit, and degradation of the major NF-kappaB inhibitor IkappaBalpha. In both cases, induction of NF-kappaB activity was attenuated by proteasome inhibitors and a mutation in ubiquitin-activating enzyme, suggesting that both UV-C and gamma radiation induce degradation of IkappaBs by means of the ubiquitin/proteasome pathway. However, although the induction of IkappaBalpha degradation by gamma rays was dependent on its phosphorylation at Ser-32 and Ser-36, UV-C-induced IkappaBalpha degradation was not dependent on phosphorylation of these residues. Even the "super repressor" IkappaBalpha mutant, which contains alanines at positions 32 and 36, was still susceptible to UV-C-induced degradation. Correspondingly, we found that gamma radiation led to activation of IKK, the protein kinase that phosphorylates IkappaBalpha at Ser-32 and Ser-36, whereas UV-C radiation did not. Furthermore, expression of a catalytically inactive IKKbeta mutant prevented NF-kappaB activation by gamma radiation, but not by UV-C. These results indicate that gamma radiation and UV-C activate NF-kappaB through two distinct mechanisms.

Comparative efficacy of alternative hand-washing agents in reducing nosocomial infections in intensive care units

BACKGROUND

Effective hand-washing can prevent nosocomial infections, particularly in high-risk areas of the hospital. There are few clinical studies of the efficacy of specific hand-cleansing agents in preventing the transmission of pathogens from health care workers to patients.

METHODS

For eight months, we conducted a prospective multiple-crossover trial involving 1894 adult patients in three intensive care units (ICUs). In a given month, the ICU used a hand-washing system involving either chlorhexidine, a broad-spectrum antimicrobial agent, or 60 percent isopropyl alcohol with the optional use of a nonmedicated soap; in alternate months the other system was used. Rates of nosocomial infection and hand-washing compliance were monitored prospectively.

RESULTS

When chlorhexidine was used, there were 152 nosocomial infections, as compared with 202 when the combination of alcohol and soap was used (adjusted incidence-density ratio [IDR], 0.73; 95 percent confidence interval, 0.59 to 0.90). The largest reduction with chlorhexidine was in gastrointestinal infections (IDR, 0.19; 95 percent confidence interval, 0.05 to 0.64). When chlorhexidine was available, the rates of nosocomial infection declined in each of the ICUs, and health care workers washed their hands more often than when alcohol and soap were used (relative risk, 1.28; 95 percent confidence interval, 1.02 to 1.60). The total volume of alcohol and soap used was 46 percent that of chlorhexidine (P less than 0.001).

CONCLUSIONS

A hand-disinfection system using an antimicrobial agent (chlorhexidine) reduces the rate of nosocomial infections more effectively than one using alcohol and soap. The improvement may be explained at least in part by better compliance with hand-washing instructions when chlorhexidine was used.

The role of particulate pollutants in pulmonary inflammation and asthma: evidence for the involvement of organic chemicals and oxidative stress

We review the literature indicating that the adverse health effects of ambient particulate matter involve the generation of oxidative stress and inflammation, as well as immunomodulating effects by particle-associated chemicals. We discuss evidence that diesel exhaust particle organic extracts induce reactive oxygen species in macrophages and bronchial epithelial cells, two key cell types targeted by particulate matter in the lung. Reactive oxygen species activate the promoters of cytokines and chemokines involved in allergic inflammation through activator protein-1 and nuclear factor- kappaB signaling pathways, which may explain exacerbation of allergic inflammation. Organic diesel exhaust particle chemicals also induce apoptosis and necrosis in bronchial epithelial cells via a mitochondrial pathway. This may be responsible for epithelial shedding and bronchial hyperreactivity in asthma.

Production and actions of superoxide in the renal medulla

The present study characterized the biochemical pathways responsible for superoxide (O(2)(-.)) production in different regions of the rat kidney and determined the role of O(2)(-.)in the control of renal medullary blood flow (MBF) and renal function. By use of dihydroethidium/DNA fluorescence spectrometry with microtiter plates, the production of O(2)(-. )was monitored when tissue homogenate from different kidney regions was incubated with substrates for the major O(2)(-.)-producing enzymes, such as NADH/NADPH oxidase, xanthine oxidase, and mitochondrial respiratory chain enzymes. The production of O(2)(-. )via NADH oxidase was greater (P<0.05) in the renal cortex and outer medulla (OM) than in the papilla. The mitochondrial enzyme activity for O(2)(-.)production was higher (P<0.05) in the OM than in the cortex and papilla. Compared with NADH oxidase and mitochondrial enzymes, xanthine oxidase and NADPH oxidase produced much less O(2)(-. )in the kidney under this condition. Overall, the renal OM exhibited the greatest enzyme activities for O(2)(-.)production. In anesthetized rats, renal medullary interstitial infusion of a superoxide dismutase inhibitor, diethyldithiocarbamate, markedly decreased renal MBF and sodium excretion. Diethyldithiocarbamate (5 mg/kg per minute by renal medullary interstitial infusion [RI]) reduced the renal medullary laser-Doppler flow signal from 0.6+/-0.04 to 0.4+/-0.03 V, a reduction of 33%, and both urine flow and sodium excretion decreased by 49%. In contrast, a membrane-permeable superoxide dismutase mimetic, 4-hydroxytetramethyl-piperidine-1-oxyl (TEMPOL, 30 micromol/kg per minute RI) increased MBF and sodium excretion by 34% and 69%, respectively. These effects of TEMPOL on renal MBF and sodium excretion were not altered by pretreatment with N(G)-nitro-L-arginine methyl ester (10 microgram/kg per minute RI). We conclude that (1) renal medullary O(2)(-. )is primarily produced in the renal OM; (2) both NADH oxidase and mitochondrial enzymes are responsible for the O(2)(-.)production in this kidney region; and (3) O(2)(-. )exerts a tonic regulatory action on renal MBF.

SH2 domains prevent tyrosine dephosphorylation of the EGF receptor: identification of Tyr992 as the high-affinity binding site for SH2 domains of phospholipase C gamma

Several cytoplasmic tyrosine kinases contain a conserved, non-catalytic stretch of approximately 100 amino acids called the src homology 2 (SH2) domain, and a region of approximately 50 amino acids called the SH3 domain. SH2/SH3 domains are also found in several other proteins, including phospholipase C-gamma (PLC gamma). Recent studies indicate that SH2 domains promote association between autophosphorylated growth factor receptors such as the epidermal growth factor (EGF) receptor and signal transducing molecules such as PLC gamma. Because SH2 domains bind specifically to protein sequences containing phosphotyrosine, we examined their capacity to prevent tyrosine dephosphorylation of the EGF and other receptors with tyrosine kinase activity. For this purpose, various SH2/SH3 constructs of PLC gamma were expressed in Escherichia coli as glutathione-S-transferase fusion proteins. Our results show that purified SH2 domains of PLC gamma are able to prevent tyrosine dephosphorylation of the EGF receptor and other receptors with tyrosine activity. The inhibition of tyrosine dephosphorylation paralleled the capacity of various SH2-containing constructs to bind to the EGF receptor, suggesting that the tyrosine phosphatase and the SH2 domain compete for the same tyrosine phosphorylation sites in the carboxy-terminal tail of the EGF receptor. Analysis of the phosphorylation sites protected from dephosphorylation by PLC gamma-SH2 revealed substantial inhibition of dephosphorylation of Tyr992 at 1 microM SH2. This indicates that Tyr992 and its flanking sequence is the high-affinity binding site for SH2 domains of PLC gamma.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro and in vivo studies on a Mg-Sr binary alloy system developed as a new kind of biodegradable metal

Magnesium alloys have shown potential as biodegradable metallic materials for orthopedic applications due to their degradability, resemblance to cortical bone and biocompatible degradation/corrosion products. However, the fast corrosion rate and the potential toxicity of their alloying element limit the clinical application of Mg alloys. From the viewpoint of both metallurgy and biocompatibility, strontium (Sr) was selected to prepare hot rolled Mg-Sr binary alloys (with a Sr content ranging from 1 to 4 wt.%) in the present study. The optimal Sr content was screened with respect to the mechanical and corrosion properties of Mg-Sr binary alloys and the feasibility of the use of Mg-Sr alloys as orthopedic biodegradable metals was investigated by in vitro cell experiments and intramedullary implantation tests. The mechanical properties and corrosion rates of Mg-Sr alloys were dose dependent with respect to the added Sr content. The as-rolled Mg-2Sr alloy exhibited the highest strength and slowest corrosion rate, suggesting that the optimal Sr content was 2 wt.%. The as-rolled Mg-2Sr alloy showed Grade I cytotoxicity and induced higher alkaline phosphatase activity than the other alloys. During the 4 weeks implantation period we saw gradual degradation of the as-rolled Mg-2Sr alloy within a bone tunnel. Micro-computer tomography and histological analysis showed an enhanced mineral density and thicker cortical bone around the experimental implants. Higher levels of Sr were observed in newly formed peri-implant bone compared with the control. In summary, this study shows that the optimal content of added Sr is 2 wt.% for binary Mg-Sr alloys in the rolled state and that the as-rolled Mg-2Sr alloy in vivo produces an acceptable host response.

Systemic inflammatory response syndrome, sepsis, severe sepsis and septic shock: incidence, morbidities and outcomes in surgical ICU patients

OBJECTIVES

To determine the incidence of systemic inflammatory response syndrome (SIRS), sepsis and severe sepsis in surgical ICU patients and define patient characteristics associated with their acquisition and outcome.

DESIGN

One-month prospective study of critically ill patients with a 28 day in-hospital follow up.

SETTING

Surgical intensive care unit (SICU) at a tertiary care institution.

METHODS

All patients (n = 170) admitted to the SICU between April 1 and April 30, 1992 were prospectively followed for 28 days. Daily surveillance was performed by two dedicated, specifically-trained research nurses. Medical and nursing chart reviews were performed, and follow up information at six and twelve months was obtained.

RESULTS

The in-hospital surveillance represented 2246 patient-days, including 658 ICU patient-days. Overall, 158 patients (93%) had SIRS for an incidence of 542 episodes/1000 patients-days. The incidence of SIRS in the ICU was even higher (840 episodes/1000 patients-days). A total of 83 patients (49%) had sepsis; among them 28 developed severe sepsis. Importantly, 13 patients had severe sepsis after discharge from the ICU. Patient groups were comparable with respect to age, sex ratio, and type of surgery performed. Apache II score on admission to the ICU and ASA score at time of surgery were significantly higher (p < 0.05) only for patients who subsequently developed severe sepsis. The crude mortality at 28 days was 8.2% (14/170); it markedly differed among patient groups: 6% for those with SIRS vs. 35% for patients with severe sepsis. Patients with sepsis and severe sepsis had a longer mean length of ICU stay (2.1 +/- 0.2 and 7.5 +/- 1.5, respectively) than those with SIRS (1.45 +/- 0.1) or control patients (1.16 +/- 0.1). Total length of hospital stay also markedly differed among groups (35 +/- 9 (severe sepsis), 24 +/- 2 (sepsis), 11 +/- 0.8 (SIRS), and 9 +/- 0.1 (controls, respectively).

CONCLUSIONS

Almost everyone in the SICU had SIRS. Therefore, because of its poor specificity, SIRS was not helpful predicting severe sepsis and septic shock. Patients who developed sepsis or severe sepsis had higher crude mortality and length of stay than those who did not. Studies designed to identify those who develop complications of SIRS would be very useful.

Induction of heme oxygenase-1 expression in macrophages by diesel exhaust particle chemicals and quinones via the antioxidant-responsive element

Diesel exhaust particles (DEP) contain organic chemicals that contribute to the adverse health effects of inhaled particulate matter. Because DEP induce oxidative stress in the lung and in macrophages, effective antioxidant defenses are required. One type of defense is through the expression of the antioxidant enzyme, heme oxygenase I (HO-1). HO-1 as well as phase II detoxifying enzymes are induced via antioxidant response elements (ARE) in their promoters of that gene. We show that a crude DEP total extract, aromatic and polar DEP fractions, a benzo(a)pyrene quinone, and a phenolic antioxidant induce HO-1 expression in RAW264.7 cells in an ARE-dependent manner. N-acetyl cysteine and the flavonoid, luteolin, inhibited HO-1 protein expression. We also demonstrate that the same stimuli induce HO-1 mRNA expression in parallel with the activation of the SX2 enhancer of that gene. Mutation of the ARE core, but not the overlapping AP-1 binding sequence, disrupted SX2 activation. Finally, we show that biological agents, such as oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine, could also induce HO-1 expression via an ARE-dependent mechanism. Prior induction of HO-1 expression, using cobalt-protoporphyrin, protected RAW264.7 cells against DEP-induced toxicity. Taken together, these data show that HO-1 plays an important role in cytoprotection against redox-active DEP chemicals, including quinones.

The tyrosine phosphorylated carboxyterminus of the EGF receptor is a binding site for GAP and PLC-gamma

Phospholipase C-gamma (PLC-gamma) and GTPase activating protein (GAP) are substrates of EGF, PDGF and other growth factor receptors. Since either PLC-gamma or GAP also bind to the activated receptors it was suggested that their SH2 domains are mediating this association. We attempted to delineate the specific region of the EGF receptor that is responsible for the binding, utilizing EGF receptor mutants, PLC-gamma, and a bacterially expressed TRP E fusion protein containing the SH2 domains of GAP. As previously shown, tyrosine autophosphorylation of the wild-type receptor wsa crucial in mediating the association and in agreement, a kinase negative EGF receptor could bind PLC-gamma or TRP E GAP SH2, but only when cross tyrosine phosphorylated by an active EGF receptor kinase. The importance of autophosphorylation for association was confirmed by demonstrating that a carboxy-terminal deletion of the EGFR missing four autophosphorylation sites bound these proteins poorly. To study the role of EGF receptor autophosphorylation further, a 203 amino acid EGF receptor fragment was generated with cyanogen bromide that contained all known tyrosine autophosphorylation sites. This fragment bound both TRP E GAP SH2 and PLC-gamma but only when tyrosine phosphorylated. This data localizes a major binding site for SH2 domain containing proteins to the carboxy-terminus of the EGF receptor and points to the importance of tyrosine phosphorylation in mediating this association.

Resonance Rayleigh scattering study of the interaction of heparin with some basic diphenyl naphthylmethane dyes

In a near-neutral medium, a combination of heparin with some basic diphenyl naphthylmethane dyes such as victoria blue 4R (VB4R), victoria blue B (VBB), or night blue (NB) can result in a significant enhancement of resonance. Rayleigh scattering (RRS) and their maximum scattering wavelengths lambdamax appear at 523, 534, and 540 nm for VB4R, VBB, and NB, respectively. The characteristics of RRS spectra of the heparin-dye complexes, the influencing factors, and the optimum conditions of these reactions have been investigated. The RRS intensity is directly proportional to the concentration of heparin in the range of approximately 0 to 0.4 microg/mL for all systems. The methods exhibit high sensitivities, and the detection limits for heparin are 3.35 ng/mL for the VB4R system, 6.62 ng/ mL for the VBB system, and 6.29 ng/mL for the NB system. Because the VB4R system is the most sensitive, it was taken as an example to study the selectivity of the method. A new method for the determination of trace amounts of heparin based on RRS technique has been developed. Moreover, the enhancement reasons of RRS and the relationship between RRS spectral characteristics of the heparin-dye complex and its absorption spectra have been primarily discussed.

Microbiological factors influencing the outcome of nosocomial bloodstream infections: a 6-year validated, population-based model

All patients (n = 1,745) with nosocomial bloodstream infection identified between 1986 and 1991 at a single 900-bed tertiary care hospital were studied to identify microbiological factors independently associated with mortality due to the infection. Patients were identified by prospective, case-based surveillance and positive blood cultures. Mortality rates were examined for secular trends. Prognostic factors were determined with use of univariate and multivariate analyses, and both derivation and validation sets were used. A total of 1,745 patients developed nosocomial bloodstream infection. The 28-day crude mortality was 22%, and crude in-hospital mortality was 35%. Factors independently (all P < .05) associated with increased 28-day mortality rates were older age, longer length of hospital stay before bloodstream infection, and a diagnosis of cancer or disease of the digestive system. After adjustment for major confounders, Candida species were the only organisms independently influencing the outcome of nosocomial bloodstream infection (odds ratio [OR] for mortality = 1.84; 95% confidence interval [CI], 1.22-2.76; P = .0035). The two additional microbiological factors independently associated with increased mortality were pneumonia as a source of secondary infection (OR = 2.74; 95% CI, 1.87-4.00; P < .0001) and polymicrobial infection (OR = 1.68; 95% CI, 1.22-2.32; P = .0014). Our data suggest that microbiological factors independently affect the outcome of nosocomial bloodstream infection.

Proposal of the genera Anaerococcus gen. nov., Peptoniphilus gen. nov. and Gallicola gen. nov. for members of the genus Peptostreptococcus

Members of genus Peptostreptococcus have previously been found to be distantly related to the type species, Peptostreptococcus anaerobius, on the basis of 16S rDNA sequence similarities. They were divided into three major phylogenetic groups, and their peptidoglycan structure and biochemical traits differed between groups. The reclassification of the species of these three groups into three new genera, Peptoniphilus gen. nov., Anaerococcus gen. nov. and Gallicola gen. nov., is proposed. The genus Peptoniphilus gen. nov. includes the following butyrate-producing, non-saccharolytic species that use peptone and amino acids as major energy sources: Peptoniphilus asaccharolyticus comb. nov. (type species), Peptoniphilus lacrimaris comb. nov., Peptoniphilus harei comb. nov., Peptoniphilus indolicus comb. nov. and Peptoniphilus ivorii comb. nov. The genus Anaerococcus gen. nov. contains the saccharolytic, butyrate-producing species Anaerococcus prevotii comb. nov. (type species), Anaerococcus tetradius comb. nov., Anaerococcus lactolyticus comb. nov., Anaerococcus hydrogenalis comb. nov., Anaerococcus vaginalis comb. nov. and Anaerococcus octavius sp. nov. The genus Gallicola gen. nov. contains a single species, Gallicola barnesae comb. nov.

Blood pressure lowering and major cardiovascular events in people with and without chronic kidney disease: meta-analysis of randomised controlled trials

OBJECTIVE

To define the cardiovascular effects of lowering blood pressure in people with chronic kidney disease.

DESIGN

Collaborative prospective meta-analysis of randomised trials.

DATA SOURCES AND ELIGIBILITY

Participating randomised trials of drugs to lower blood pressure compared with placebo or each other or that compare different blood pressure targets, with at least 1000 patient years of follow-up per arm.

MAIN OUTCOME MEASURES

Major cardiovascular events (stroke, myocardial infarction, heart failure, or cardiovascular death) in composite and individually and all cause death.

PARTICIPANTS

26 trials (152,290 participants), including 30,295 individuals with reduced estimated glomerular filtration rate (eGFR), which was defined as eGFR <60 mL/min/1.73 m(2).

DATA EXTRACTION

Individual participant data were available for 23 trials, with summary data from another three. Meta-analysis according to baseline kidney function was performed. Pooled hazard ratios per 5 mm Hg lower blood pressure were estimated with a random effects model.

RESULTS

Compared with placebo, blood pressure lowering regimens reduced the risk of major cardiovascular events by about a sixth per 5 mm Hg reduction in systolic blood pressure in individuals with (hazard ratio 0.83, 95% confidence interval 0.76 to 0.90) and without reduced eGFR (0.83, 0.79 to 0.88), with no evidence for any difference in effect (P=1.00 for homogeneity). The results were similar irrespective of whether blood pressure was reduced by regimens based on angiotensin converting enzyme inhibitors, calcium antagonists, or diuretics/β blockers. There was no evidence that the effects of different drug classes on major cardiovascular events varied between patients with different eGFR (all P>0.60 for homogeneity).

CONCLUSIONS

Blood pressure lowering is an effective strategy for preventing cardiovascular events among people with moderately reduced eGFR. There is little evidence from these overviews to support the preferential choice of particular drug classes for the prevention of cardiovascular events in chronic kidney disease.