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.

Application de l’approche globale de l’alimentation dans la population belge

BACKGROUND

Dietary pattern analysis has recently emerged as a new direction and a complementary approach to study the relationship between diet and morbidity or mortality. At present, two methods have been developed to construct dietary patterns: "a priori" method and "a posteriori" method.

OBJECTIVE

This paper presents the two methods and their application based on dietary data from the "Belgium Interuniversity on Nutrition and Health Study".

METHODS

A prospective study was conducted (1979-1984) in a sample of 5,225 males and 4,476 females from the Belgian population aged 25 to 74 years at the initial survey and followed for 10 years for all causes and specific mortality. Dietary data was collected by a 24-hour recall and for a sub-sample also by a 7 day-diet record. The "a priori" method was used by calculating an index based on the national dietary guidelines. We used the principal component analysis to identify dietary patterns a posteriori. We conducted a first principal component analysis using the data from the 24-hour recall and a second on the data collected by the 7 day-record.

RESULTS

Both of the currently used approaches for extracting dietary patterns have advantages and limitations. We applied first the "a priori" approach by calculating an Index (IAR) which measures the adherence of the sample to the Belgian dietary guidelines. We obtained an index that ranged from 0 to 8, a higher score represented a "healthier diet". The index mean (sd) was 3.7 (+/- 1.2) for the entire sample with a significantly higher IAR for women. Using factor analysis, we identified 8 dietary patterns for men and for women. These were difficult to translate in terms of dietary intake profile. Inversely, with the factors identified with the 7 day record, we could find a "western" dietary profile and a "prudent" profile.

CONCLUSION

Dietary pattern analysis offers the opportunity to evaluate the overall quality of the diet. The dietary profiles constructed by the two approaches should be related to morbidity or mortality in order to evaluate their predictive capacity.

Kinetics of target site localization of a protein on DNA: a stochastic approach

It is widely recognized that the cleaving rate of a restriction enzyme on target DNA sequences is several orders-of-magnitude faster than the maximal one calculated from the diffusion-limited theory. It was therefore commonly assumed that the target site interaction of a restriction enzyme with DNA has to occur via two steps: one-dimensional diffusion along a DNA segment, and long-range jumps coming from association-dissociation events. We propose here a stochastic model for this reaction which comprises a series of one-dimensional diffusions of a restriction enzyme on nonspecific DNA sequences interrupted by three-dimensional excursions in the solution until the target sequence is reached. This model provides an optimal finding strategy which explains the fast association rate. Modeling the excursions by uncorrelated random jumps, we recover the expression of the mean time required for target site association to occur given by Berg et al. in 1981, and we explicitly give several physical quantities describing the stochastic pathway of the enzyme. For competitive target sites we calculate two quantities: processivity and preference. By comparing these theoretical expressions to recent experimental data obtained for EcoRV-DNA interaction, we quantify: 1), the mean residence time per binding event of EcoRV on DNA for a representative one-dimensional diffusion coefficient; 2), the average lengths of DNA scanned during the one-dimensional diffusion (during one binding event and during the overall process); and 3), the mean time and the mean number of visits needed to go from one target site to the other. Further, we evaluate the dynamics of DNA cleavage with regard to the probability for the restriction enzyme to perform another one-dimensional diffusion on the same DNA substrate following a three-dimensional excursion.

Perceived job stress and incidence of coronary events: 3-year follow-up of the Belgian Job Stress Project cohort

Psychosocial characteristics have been linked to coronary heart disease. In the Belgian Job Stress Project (1994-1999), the authors examined the independent role of perceived job stress on the short-term incidence of clinical manifest coronary events in a large occupational cohort. A total of 14,337 middle-aged men completed the Job Content Questionnaire to determine the dimensions of the extended job strain model, job demands, decision latitude, and social support. Jobs were categorized into high strain, low strain, active jobs, and passive jobs. During the 3-year follow-up, 87 coronary events were registered. At baseline, 17% of workers experienced high strain. Job demands and decision latitude were not significantly related to the development of coronary heart disease after adjustment for covariates. The 38% risk excess among subjects classified in the high-strain category did not reach statistical significance. However, coronary heart disease incidence was substantially associated with the social support scale independently of other risk factors, with an adjusted hazard ratio of 2.4 (95% confidence interval: 1.4, 4.0) between extreme tertiles. No convincing evidence for an association of job demands, decision latitude, or job strain with the short-term incidence of coronary heart disease was found. However, our study underscores the importance of a supportive social work environment in the prevention of coronary heart disease.

Corrections to the law of mass action and properties of the asymptotic t=∞ state for reversible diffusion-limited reactions

For diffusion-limited reversible A+A<==>B reactions we reexamine two fundamental concepts of classical chemical kinetics-the notion of "chemical equilibrium" and the "law of mass action." We consider a general model with distance-dependent reaction rates, such that any pair of A particles, performing standard random walks on sites of a d-dimensional lattice and being at a distance mu apart of each other at time moment t, may associate forming a B particle at the rate k+(mu). In turn, any randomly moving B particle may spontaneously dissociate at the rate k-(lambda) into a geminate pair of As "born" at a distance lambda apart of each other. Within a formally exact approach based on Gardiner's Poisson representation method we show that the asymptotic t=infinity state attained by such diffusion-limited reactions is generally not a true thermodynamic equilibrium, but rather a nonequilibrium steady state, and that the law of mass action is invalid. The classical concepts hold only in case when the ratio k+(mu)k-(mu) does not depend on mu for any mu.

Two new hemoglobin variants: Hb Brem-sur-Mer [beta9(A6)Ser-->Tyr] and Hb Passy [alpha81(F2)Ser-->Pro (alpha2)]

Two new hemoglobin (Hb) variants: Hb Brem-sur-Mer [codon 9 (TCT-->TAT); beta9(A6)Ser-->Tyr] on the first exon of the beta-globin gene and Hb Passy [codon 81 (TCC-->CCC); alpha81(F2)Ser-->Pro (alpha2)] on the second exon of the alpha2-globin gene, are described. The two variants were characterized by DNA sequencing and mass spectrometry (MS). Hematological abnormalities: microcytosis and hypochromia were found only in the carrier of Hb Passy. In the absence of an association with an alpha-thalassemic deletion or mutation, the mutation 81(F2)Pro could induce a possible alpha-thalassemia (thal).

Individual and combined effects of dosages of azoxystrobin and epoxiconazole in wheat

The effects of single fungicide applications on Mycosphaerella graminicola (septoria leaf blotch) control and winter wheat yield were evaluated in field trials conducted in central Belgium between 2000 and 2004. Individual applications of 25, 50, 75 and 100% of the manufacturer's recommended dose rates of azoxystrobin and epoxiconazole, and all the combinations of these treatments, were made at GS 39 in 2001 to 2004 and at GS 59 in 2000. Disease assessments were made at growth stage 75, some 7-8 weeks after the last applications. Between 2000 and 2003, no significant difference was observed for disease control between the products when applied alone. With regard to the dose responses, the differences between the recommended dose rates and the 50% reduced dosages were not important. In 2004, azoxystrobin was less effective than epoxiconazole. This was probably the result of strobilurin-resistant isolates of M. graminicola reaching an occurrence of 32% before fungicide application. The combination of different dosages of azoxystrobin and epoxiconazole revealed that there was very little synergy between these products when applied in a single application. The combinations of these products were better than individual applications only when high dosages of both compounds were used.

Occupational stress and incidence of sick leave in the Belgian workforce: the Belstress study

CONTEXT

Sick leave is a major problem in public health. The Karasek demands/control/social support/strain (JDCS) model has been largely used to predict a wide range of health outcomes and to a lesser extent sickness absence.

STUDY OBJECTIVE

The aim of the study was to test the predictive power of the JDCS model in relation with one year incidence of sick leave in a large cohort of workers.

DESIGN AND SETTING

Cohort study conducted between 1994 and 1998 in 25 companies across Belgium.

PARTICIPANTS

A total of 20 463 workers aged 35 to 59 years were followed up for sick leave during one year after the baseline survey.

OUTCOMES

The outcomes were a high sick leave incidence, short spells (>/=7 days), long spells (>/=28 days), and repetitive spells of sickness absence (>/=3 spells/year).

MAIN RESULTS

Independently from baseline confounding variables, a significant association between high strained jobs with low social support and repetitive spells of sickness absence was observed in both sexes with odds ratios of 1.32 (99% CI, 1.04 to 1.68) in men and 1.61 (99% CI, 1.13 to 2.33) in women. In men, high strained jobs with low social support was also significantly associated with high sick leave incidence, and short spells of sick leave with odds ratios of 1.38 (99% CI, 1.16 to 1.64) and 1.22 (99% CI, 1.05 to 1.44) respectively.

CONCLUSIONS

Perceived high strain at work especially combined with low social support is predictive of sick leave in both sexes of a large cohort of the Belgian workforce.

Using magnetic resonance imaging to characterize pedicle asymmetry in both normal patients and patients with adolescent idiopathic scoliosis

STUDY DESIGN

Morphometric analysis of vertebrae from normal patients and patients with adolescent idiopathic scoliosis.

OBJECTIVES

To use magnetic resonance imaging to assess pedicle asymmetry in normal patients and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development and to determine if patients with adolescent idiopathic scoliosis exhibited a consistent vertebral morphology.

SUMMARY OF BACKGROUND DATA

To date, most studies of vertebral morphology in adolescent idiopathic scoliosis have produced conflicting data, especially on pedicle length, and have been conducted on patients in the late stages of scoliosis development, which may affect the patterns of vertebral morphology detected. Magnetic resonance imaging enables in vivo assessment of curves during development and permits improved acquisition of transverse images.

METHODS

Magnetic resonance images of 76 pedicles from 8 normal patients and 80 pedicles from 10 patients with adolescent idiopathic scoliosis were examined retrospectively. Recorded parameters included pedicle lengths, pedicle widths, pedicle areas, pedicle perimeters, and lamina lengths. The extent and direction of asymmetry in vertebrae from normal patients and patients with adolescent idiopathic scoliosis were determined and compared.

RESULTS

Normal patients displayed significant neural arch asymmetry, with the left sided measurements being greater. Patients with adolescent idiopathic scoliosis also displayed significant neural arch asymmetry; however, the longer pedicle was not consistently on the convexity or the concavity.

CONCLUSIONS

The baseline used to assess adolescent idiopathic scoliosis vertebral morphology must take into consideration the extent and direction of normal vertebral asymmetry. The pattern of vertebral asymmetry seen inadolescent idiopathic scoliosis may depend on the specific cause of the disorder, with no consistent pattern evident when data from different causes are pooled together.

Lattice theory of trapping reactions with mobile species

We present a stochastic lattice theory describing the kinetic behavior of trapping reactions A+B-->B, in which both the A and B particles perform an independent stochastic motion on a regular hypercubic lattice. Upon an encounter of an A particle with any of the B particles, A is annihilated with a finite probability; finite reaction rate is taken into account by introducing a set of two-state random variables--"gates," imposed on each B particle, such that an open (closed) gate corresponds to a reactive (passive) state. We evaluate here a formal expression describing the time evolution of the A particle survival probability, which generalizes our previous results. We prove that for quite a general class of random motion of the species involved in the reaction process, for infinite or finite number of traps, and for any time t, the A particle survival probability is always larger in the case when A stays immobile, than in situations when it moves.

Microscopic model of the actin-myosin interaction in muscular contractions

We define and study a detailed many body model for the muscular contraction taking into account the various myosin heads. The state of the system is defined by the position of the actin and by an internal coordinate of rotation for each myosin head. We write a system of Fokker-Planck equations and calculate the average for the position, the number of attached myosin heads, and the total force exerted on the actin. We also study the correlation between these quantities, in particular between the number of attached myosin heads and the force on the actin.