LDL particle subspecies are distinct in their capacity to mediate free cholesterol efflux via the SR-BI/Cla-1 receptor

The human scavenger receptor SR-BI/Cla-1 promotes efflux of free cholesterol from cells to both high-density and low-density lipoproteins (HDL, LDL). SR-BI/Cla-1-mediated cholesterol efflux to HDL is dependent on particle size, lipid content and apolipoprotein conformation; in contrast, the capacity of LDL subspecies to accept cellular cholesterol via this receptor is indeterminate. Cholesterol efflux assays were performed with CHO cells stably transfected with Cla-1 cDNA. Expression of Cla-1 in CHO cells induced elevation in total cholesterol efflux to plasma, LDL and HDL. Such Cla-1-specific efflux was abrogated by addition of anti-Cla-1 antibody. LDL were fractionated into five subspecies either on the basis of hydrated density or size. Among LDL subfractions, small dense LDL (sdLDL) were 1.5-to 3-fold less active acceptors for Cla-1-mediated cellular cholesterol efflux. Equally, sdLDL markedly reduced Cla-1-specific cholesterol efflux to large buoyant LDL in a dose-dependent manner. Conversely, sdLDL did not influence efflux to HDL(2). These findings provide evidence that LDL particles are heterogeneous in their capacity to promote Cla-1-mediated cholesterol efflux. Relative to HDL(2), large buoyant LDL may constitute physiologically-relevant acceptors for cholesterol efflux via Cla-1.

Valvular heart disease in a patient taking benfluorex

The authors describe a case of valvular heart disease in a 48-year-old woman receiving benfluorex (150 mg t.i.d. for 8 years) and leading to surgical mitral valve replacement. Examination showed severe dyspnea with severe mitral regurgitation associated with tricuspid regurgitation. No other common disease known to affect mitral valves nor intake of other drugs (ergot derivatives or appetite suppressant drugs) was found. The paper discusses the imputability of benfluorex, a drug used as an adjuvant in hypercholesterolemia, structurally related to amphetamines.

Apolipoprotein E Knockout Mice Over-Expressing Human Tissue Inhibitor of Metalloproteinase 1 Are Protected against Aneurysm Formation but Not against Atherosclerotic Plaque Development

AIMS

We investigated the effect of plasma levels of human tissue inhibitor of metalloproteinase (hTIMP)-1 on arterial lesion development and aneurysm formation in apolipoprotein-E-deficient mice (ApoE(-/-)).

METHODS

Control and transgenic mice were fed either a chow diet or a high-fat diet for 90 and 180 days.

RESULTS

hTIMP-1 has a tendency to decrease atherosclerotic lesions, but did not attain significance (approximately 6% reduction in hTIMP-1(+/+), p = 0.075, and approximately 4% in hTIMP-1(+/0), p = 0.088 vs. control). Immunohistological and histological analyses revealed a reduction in macrophage accumulation (23% of control in hTIMP(+/0), p = 0.065, and 49% of control in hTIMP(+/+), p < 0.05) but not in collagen degradation within the lesion in transgenic mice. Moreover, elastin degradation in sites of pseudo-microaneurysms was reduced in transgenic mice (37% of control in hTIMP-1(+/0), p < 0.05, and 50% of control in hTIMP-1(+/+), p < 0.05). DNA array analysis of matrix metalloproteinase (MMP) expression followed by real-time PCR quantification revealed a significant up-regulation of MMP-3, MMP-12 and MMP-13 in arterial lesions of ApoE(-/-) mice fed a high-fat diet in comparison with the same mice fed a chow diet.

CONCLUSION

These data show that hTIMP-1 reduces aneurysm formation in ApoE(-/-) mice but does not protect them against the development of arterial lesions.

Two-dimensional intermittent search processes: An alternative to Lévy flight strategies

Lévy flights are known to be optimal search strategies in the particular case of revisitable targets. In the relevant situation of nonrevisitable targets, we propose an alternative model of two-dimensional (2D) search processes, which explicitly relies on the widely observed intermittent behavior of foraging animals. We show analytically that intermittent strategies can minimize the search time, and therefore do constitute real optimal strategies. We study two representative modes of target detection and determine which features of the search time are robust and do not depend on the specific characteristics of detection mechanisms. In particular, both modes lead to a global minimum of the search time as a function of the typical times spent in each state, for the same optimal duration of the ballistic phase. This last quantity could be a universal feature of 2D intermittent search strategies.

The interaction of natural hepatitis C virus with human scavenger receptor SR-BI/Cla1 is mediated by ApoB-containing lipoproteins

The possible role of candidate receptors in the cellular penetration of HCV from serum of infected patients remains unclear. SR-BI/Cla1 interacts with plasma HDL, native and modified LDL, and VLDL, and facilitates cellular cholesterol efflux to lipoprotein acceptors. SR-BI/Cla1 binds HCV E2 protein and interacts with HCV pseudotypes via the HVR1 of the E2 envelope glycoprotein. Our data reveal that functional SR-BI/Cla1 expressed on the surface of CHO cells mediates the binding and uptake of HCV from the sera of infected patients. Interaction between HCV and SR-BI/Cla1 is not sensitive to either anti-E2 or anti-HVR1 antibodies but is effectively inhibited by anti-betalipoprotein antibodies and competed out by apoB-containing lipoproteins and notably by VLDL. We interpret our data to indicate that VLDL associated with or incorporated into HCV plays a critical role in the primary interaction of HCV with SR-BI/Cla1, whereas the HCV E2 protein does not. In addition, our findings in hepatoma cell lines suggest that the interaction of HCV with human hepatocytes is equally mediated, at least in a part, by VLDL, and as such may represent an alternative pathway for infection. The association of HCV with ApoB-containing lipoproteins may promote cellular uptake of this virus in the presence of neutralizing antibodies.

Intra-operative spinal load and displacement monitoring: towards a better understanding of scoliosis correction mechanics

Surgical correction of scoliosis reduces deformation and improves overall function and esthetics. Understanding and monitoring of mechanics during scoliosis surgery is an invaluable tool to optimize correction without compromising patient safety. Our objective was to use intra-operative monitoring tools to study how spinal load and displacement relates to obtained correction and chosen instrumentation. Instrumented pedicle screws, a "gripper" and active markers were developed. Instrumented pedicle screws provided three-dimensional forces at the screw-vertebra interface while the instrumented "gripper" measured the force and the rotation applied by the surgeon to the rod rotator. Vertebral displacement was monitored with light-emitting diodes and motion capture technology. These instruments were used successfully with 16 scoliosis subjects. Analysis of applied force, displacement, and curve flexibility influence on correction percentage is the long term goal. Raw results for instrumented screws and gripper showed that recorded force decreased with respect to percentage of correction obtained. Measured force increased with respect to the pre-surgical Cobb angle while percentage of correction obtained decreased as pre-surgical Cobb angle increased. Active marker results showed three-dimensional vertebral rotation and translation during correction, with axial rotation and caudal-cranial translation having the greatest magnitudes. Using greater correction forces does not necessarily result in an increased correction; flexibility and Cobb angle also play a role in the mechanics of correction. Further data collection will provide better understanding of the interconnected role between these factors helping complete the description of surgery mechanics.

Prediction of brace treatment outcomes by monitoring brace usage

Brace treatment is the most commonly used non-surgical treatment method for adolescent idiopathic scoliosis (AIS). This study determined whether curve progression can be predicted by how often and how well children with AIS wear their braces. Twenty subjects (3M, 17F) who were diagnosed with AIS and had worn their braces from six months up to 1 year participated into this study. All subjects were prescribed Boston style braces and have now completed their brace treatment. On average, the brace was used 57% of the prescribed time. Peterson's risk of progression (Risser sign, age, apex of curve and imbalance of curve) predicted only 3-8% of the curve progression of brace subjects. Knowing how brace subjects used their braces in terms of brace tightness increases the prediction rate to 12-21%; and wear time further increase it to 25-36%. Adding the multiple of brace tightness and wear time improves curve progression prediction to 41-54%. To be most effective, the brace should be worn as prescribed in both tightness and time manners.

Associations between quality-of-life and internal or external spinal deformity measurements in adolescent with idiopathic scoliosis (AIS)

In theory, quality-of-life measures should correlate with impairments such as spinal deformity. The goal was to determine the ability of the SRS-22 and surface topography measures to predict internal deformity. Data from 227 females with AIS were collected. Correlations and regression were used to predict Cobb angle or category. In subjects treated conservatively, the Cobb angle correlated with pain, self-image, satisfaction and total score. Only self-image correlated with surface topography. In subjects having had surgery, Cobb angle correlated with self-image, mental health, satisfaction and total scores. The cosmetic score was the only external deformity measure to correlate with the SRS-22. Function, self-image and trunk-twist predicted subjects within 3 categories (Cobb <30 degrees , 30-50 degrees , >50 degrees) with 57% accuracy compared to 53% when using self-image only. Accuracy in predicting subjects with curves smaller or larger than 50 degrees was 79% (using self-image, trunk-twist) or 72% (self-image only). Correlations between quality-of-life and deformity measures were low. However, it was possible to predict subjects within clinically meaningful categories of internal deformity using SRS-22 scores.

Improving brace wear with active brace system

There is considerable controversy regarding the effectiveness of brace treatment for patients with adolescent idiopathic scoliosis (AIS). Researchers believe that to be effective, patients must wear their braces as prescribed including both compliance and tightness. Compliance is how much time the brace is worn relative to the prescribed time. Brace tightness is usually prescribed by orthotists during brace fitting session. Asking the patient or examining the brace for wear are the most common methods to evaluate the brace usage. A low powered microcomputer system was developed to monitor and maintain loads exerted by braces used to treat children with spinal deformities during daily living. This system records brace usage information and helps patients to wear their brace at the prescribed tightness. Laboratory tests have been performed and six patients have used the system for four weeks. The patients reported that the system helped them to wear the brace properly. The time that the patients wore the braces at the prescribed tightness level increased from 48+/-16% during the monitor period (first 2 weeks) to 63+/-18% during the automatic adjustment period (last 2 weeks).

First-passage times for random walks in bounded domains

We present a novel computational method of first-passage times between a starting site and a target site of regular bounded lattices. We derive accurate expressions for all the moments of this first-passage time, validated by numerical simulations. Their range of validity is discussed. We also consider the case of a starting site and two targets. In addition, we present the extension to continuous Brownian motion. These results are of great relevance to any system involving diffusion in confined media.

Kinetics of diffusion-limited catalytically activated reactions: An extension of the Wilemski–Fixman approach

We study the kinetics of diffusion-limited catalytically activated A+B-->B reactions taking place in three-dimensional systems, in which an annihilation of diffusive A particles by diffusive traps B may happen only if the encounter of an A with any of the Bs happens within a special catalytic subvolumen: these subvolumens being immobile and uniformly distributed within the reaction bath. Suitably extending the classical approach of Wilemski and Fixman [J. Chem. Phys. 58, 4009 (1973)] to such three-molecular diffusion-limited reactions, we calculate analytically an effective reaction constant and show that it comprises several terms associated with the residence and joint residence times of Brownian paths in finite domains. The effective reaction constant exhibits a nontrivial dependence on the reaction radii, the mean density of catalytic subvolumens, and particles' diffusion coefficients. Finally, we discuss the fluctuation-induced kinetic behavior in such systems.

Lethal effect of the gliding arc discharges on Erwinia spp

AIMS

To compare the decontamination performances of glidarc on strains of Erwinia of industrial interest.

METHODS AND RESULTS

Cultures of Erwinia carotovora carotovora, Erwinia carotovora atroseptica and Erwinia chrysanthemi taken in stationary phase were exposed to the plasma generated by electric discharges in a gliding arc reactor prototype. The kinetics of destruction of bacteria were followed by direct platting. All bacterial strains presented a three-phase destruction kinetics leading to an apparent sterilization within 10 min. Epifluorescent observations using life/dead probes revealed the absence of viable but not cultivable resistant forms. Measurement of the physical parameters of the medium confirmed that the technique was nonthermal but that reactive species responsible for a decrease of the pH were generated. However, even after neutralization the medium did not allow bacterial growth.

CONCLUSIONS

The results demonstrate that glidarc allows a rapid and complete destruction of planctonic strains of Erwinias without formation of resistant forms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The reduction rate obtained by this technique shows the great industrial interest of glidarc for decontamination and suggests that it can be used for sterilization of industrial water effluents.

Cloning and expression of the amphibian homologue of the human PKD1 gene

PKD1 is the gene responsible for autosomal dominant polycystic kidney disease (ADPKD) type 1 in humans. The PKD1 gene product is likely to be a calcium channel regulator. In this paper, we describe the isolation and characterization of the Xenopus homologue of the human PKD1 gene. We isolated and cloned genomic fragments corresponding to the amphibian homologue of PKD1 from a BAC library, and after sequencing the clones, we designed primers for the amplification of the transcript and sequenced 10 kb of ORF. The sequence of the putative protein clearly demonstrated that this gene is the homologue of human PKD1. Analysis of the tissue expression patterns of xPKD1 demonstrated a high level of expression in the kidney. A similar analysis in developing embryos and in an in vitro nephrogenic system suggests that xPKD1 is associated with, and probably involved in, the development of the amphibian pronephros.

Atypical shoulder muscle activation in multidirectional instability

OBJECTIVE

Surface and intramuscular electromyography was used to investigate shoulder muscle activity in subjects with multidirectional instability (MDI).

METHODS

Subjects (seven MDI, 11 control) performed repetitive shoulder abduction/adduction, flexion/extension and internal/external rotation movements on an isokinetic dynamometer. The activity of the deltoid, infraspinatus, supraspinatus, latissimus dorsi, and pectoralis major muscles were recorded using double-differential surface and intramuscular fine-wire electrodes. A repeated measures analysis of variance evaluated group differences in the amplitude, onset, termination and duration of the muscle activity.

RESULTS

Significant activation parameter differences for the supraspinatus, infraspinatus, posterior deltoid and pectoralis major muscles were found in the subjects with MDI. The rotator cuff and posterior deltoid muscles demonstrated abbreviated periods of activity when performing internal/external rotation, despite activation amplitudes that were similar to the controls. In contrast, the activation of the pectoralis major differed from the control group in both the amplitude and time domains when performing shoulder extension.

CONCLUSIONS

MDI is associated with atypical patterns of muscle activity that occur even when highly constrained movements are used to elicit the activity.

SIGNIFICANCE

In addition to glenohumeral hyperlaxity, the results suggest that dysfunctional neuromuscular control of the rotator cuff is also a contributing factor to the pathoetiology of MDI.

First-exit times and residence times for discrete random walks on finite lattices

In this paper, we derive explicit formulas for the surface averaged first-exit time of a discrete random walk on a finite lattice. We consider a wide class of random walks and lattices, including random walks in a nontrivial potential landscape. We also compute quantities of interest for modeling surface reactions and other dynamic processes, such as the residence time in a subvolume, the joint residence time of several particles, and the number of hits on a reflecting surface.

Optimal search strategies for hidden targets

What is the fastest way of finding a randomly hidden target? Experimental observations reveal that the search behavior of foraging animals is generally intermittent: active search phases randomly alternate with phases of fast ballistic motion. Here, we study the efficiency of this two state search strategy by calculating analytically the mean first passage time at the target. We model the perception mechanism involved in the active search phase by a diffusive process. We show that the search strategy is optimal when the average duration of "motion phases" varies like the power either 3/5 or 2/3 of the average duration of "search phases" depending on the regime. This scaling accounts for experimental data over a wide range of species, which suggests that the kinetics of search trajectories is a determining factor optimized by foragers and that the perception activity is adequately described by a diffusion process.

Superiority of the gastroduodenal safety profile of licofelone over rofecoxib, a COX-2 selective inhibitor, in dogs

This study assessed the gastroduodenal safety profile of licofelone, a new nonsteroidal anti-inflammatory drug with dual inhibitory activity against 5-lipoxygenase and cyclo-oxygenase (COX), by using endoscopic evaluations and by comparing licofelone to rofecoxib, a selective COX-2 inhibitor. Twenty-one dogs underwent blinded gastroduodenoscopies, during which the mucosa of the gastroduodenal tract was assessed and scored. Blood analyses were monitored on days 0 (baseline), 14, 28, 42, and 56. Examinations to detect fecal occult blood were performed daily. Dogs were randomly assigned to three groups that received either a placebo, licofelone at a dose of 2.5 mg/kg twice daily, or rofecoxib at a dose of 0.5 mg/kg daily, respectively. Significant differences between the groups in gastric (P = 0.003), duodenal (P = 0.009), and gastroduodenal (P = 0.002) endoscopic lesion scores were observed at day 56. Rofecoxib-treated dogs had more lesions in all areas when compared with placebo-treated dogs, more duodenal lesions when compared with licofelone-treated dogs and more lesions than they had at baseline. In contrast to licofelone, rofecoxib was found to induce significant gastric and gastroduodenal lesions in dogs that lacked pre-existing lesions at baseline. Blood analyses and fecal examinations did not reveal abnormalities in any of the experimental groups. Treatment with licofelone was well tolerated and was shown to be safer than rofecoxib in terms of upper gastrointestinal damage. In this way, this study demonstrates the gastroduodenal safety profile of licofelone for chronic treatment.