Stepping boundary of external force-controlled perturbations of varying durations: Comparison of experimental data and model simulations.

This study investigated the stepping boundary - the force that can be resisted without stepping - for force-controlled perturbations of different durations. Twenty-two healthy young adults (19-37 years old) were instructed to try not to step in response to 86 different force/time combinations of forward waist-pulls. The forces at which 50% of subjects stepped (F50) were identified for each tested perturbation durations. Results showed that F50 decreased hyperbolically when the perturbation's duration increased and converged toward a constant value (about 10%BW) for longer perturbations (over 1500 ms). The effect of perturbation duration was critical for the shortest perturbations (less than 1 s). In parallel, a simple function was proposed to estimate this stepping boundary. Considering the dynamics of a linear inverted pendulum + foot model and simple balance recovery reactions, we could express the maximum pulling force that can be withstood without stepping as a simple function of the perturbation duration. When used with values of the main model parameters determined experimentally, this function replicated adequately the experimental results. This study demonstrates for the first time that perturbation duration has a major influence on the outcomes of compliant perturbations such as force-controlled pulls. The stepping boundary corresponds to a constant perturbation force-duration product and is largely explained by only two parameters: the reaction time and the displacement of the center of pressure within the functional base of support. Future work should investigate pathological populations and additional parameters characterizing the perturbation time-profile such as the time derivative of the perturbation.

[A surgical follow-up platform to reduce complications in free flap surgery]. / Une plateforme de suivi chirurgical pour réduire les complications en reconstruction par lambeau libre.

STUDY OBJECTIVE: In 2007, the WHO adopted surgical safety as the theme for the 2nd global patient safety challenge. Measurement of surgical services was identified as a surgical care area in need of major improvements. Aware of this recommendation, a preliminary study was conducted in our hospital and showed that the incidence of complete necrosis in free flap surgery was 10.0 %, a rate among the highest found in medical literature. In that context, an interactive surgical follow-up platform (PICS) was implemented to monitor outcomes in free flap surgery. The hypothesis was to reduce the short-term failure of microsurgical reconstructions. PATIENTS AND METHODS: In Summer 2010, the tool for capturing and analyzing data (PICS) was implemented. All patients who underwent free flap reconstruction were prospectively registered in the platform. The primary endpoints to evaluate the effectiveness of the tool are the rates of surgical re-exploration and complete necrosis of the flap. RESULTS: From May 2010 to December 2011, 129 cases of free flap reconstruction were recorded. The rate of total flap necrosis was 10.0 % before database introduction and declined to 3.1 % afterwards (P<0.05). Take-backs occurred in 27.0 % of free flap reconstructions at baseline and in 10.1 % after implementation (P<0.01). CONCLUSION: The implementation of PICS is associated with a significant improvement of postoperative short-term outcomes in free flap surgery. This tool is effective to evaluate care services and provides an increased surgical safety for patients. Surgical teams are encouraged to implement a data collection tool in order evaluate operative care on a routine basis.

Screening cervical spine CT in the emergency department, Phase 2: A prospective assessment of use.

BACKGROUND AND PURPOSE: The National Emergency X-Radiography Utilization Study Low-Risk Criteria were established to identify patients with a low probability of cervical spine injury in whom imaging of the cervical spine was unnecessary. The purpose of this study was to ascertain the number of unnecessary cervical spine CT studies on the basis of proper application of established clinical guidelines and, secondarily, to determine indications for ordering studies in the absence of guideline criteria. MATERIALS AND METHODS: All patients presenting to a level I trauma center for whom a screening cervical spine CT was ordered in the setting of blunt trauma were eligible for enrollment. For each study, the requesting clinician completed a survey regarding study indications. CT examinations were evaluated by a board-certified radiologist blinded to survey data to determine the presence or absence of cervical spine injury. RESULTS: Of 507 CT examinations, 5 (1%) were positive and 497 (98.0%) were negative for acute cervical spine injury. Five studies (1%) were indeterminate for acute injury but demonstrated no abnormality on subsequent imaging and clinical follow-up. Of the 502 studies without cervical spine injury, 81 (16.1%) were imaged despite meeting all 5 NEXUS criteria for nonimaging. Of these, the most common study indication was dangerous mechanism of injury (48.1%) followed by subjective neck pain (40.7%). CONCLUSIONS: Strict application of NEXUS criteria could potentially reduce the number of screening cervical spine CT scans in the setting of blunt trauma; this change would avoid a considerable amount of unnecessary radiation and cost.

Molecular and phenotypic characterization of near isogenic lines at QTL for quantitative resistance to Leptosphaeria maculans in oilseed rape (Brassica napus L.).

The most common and effective way to control phoma stem canker (blackleg) caused by Leptosphaeria maculans in oilseed rape (Brassica napus) is by breeding resistant cultivars. Specific resistance genes have been identified in B. napus and related species but in some B. napus cultivars resistance is polygenic [mediated by quantitative trait loci (QTL)], postulated to be race non-specific and durable. The genetic basis of quantitative resistance in the French winter oilseed rape 'Darmor', which was derived from 'Jet Neuf', was previously examined in two genetic backgrounds. Stable QTL involved in blackleg resistance across year and genetic backgrounds were identified. In this study, near isogenic lines (NILs) were produced in the susceptible background 'Yudal' for four of these QTL using marker-assisted selection. Various strategies were used to develop new molecular markers, which were mapped in these QTL regions. These were used to characterize the length and homozygosity of the 'Darmor-bzh' introgressed segment in the NILs. Individuals from each NIL were evaluated in blackleg disease field trials and assessed for their level of stem canker in comparison to the recurrent line 'Yudal'. The effect of QTL LmA2 was clearly validated and to a lesser extent, QTL LmA9 also showed an effect on the disease level. This work provides valuable material that can be used to study the mode of action of genetic factors involved in L. maculans quantitative resistance.

Stabilization of Resistance to Leptosphaeria maculans in Brassica napus-B. juncea Recombinant Lines and Its Introgression into Spring-Type Brassica napus.

The value of Katanning Early Maturing (KEM) breeding lines from Western Australia, derived from Brassica napus × B. juncea crosses, was assessed as a source of germplasm for resistance to blackleg disease (caused by Leptosphaeria maculans) in spring-type oilseed rape cultivars. The stability of blackleg resistance in these KEM lines was related to key cytological characteristics to determine why there are poor levels of introgression of this resistance into progeny. Promising recombinant KEM lines were crossed with the spring-type B. napus cv. Dunkeld, which has useful polygenic resistance to blackleg, and screened for resistance. The lines were analyzed cytologically for pairing of bivalents in each generation to aid in the selection of stable recombinant lines. KEM recombinant lines showing regular meiotic behavior and a high level of blackleg resistance were obtained for the first time. We also showed that the stable introgression of the B. juncea resistance from the KEM lines into a 'Dunkeld' background was possible. Inoculation of selfing and backcross populations with isolates of L. maculans having different AvrLm genes indicated that the B. juncea resistance gene, Rlm6, had been introgressed into a B. napus spring-type cultivar carrying polygenic resistance. The combination of both resistances would enhance the overall effectiveness of resistance against L. maculans. This is clearly needed in Australia and France where cultivars relying upon single dominant gene-based resistance for their effectiveness have proved not durable.

Detection, introgression and localization of genes conferring specific resistance to Leptosphaeria maculans from Brassica rapa into B. napus.

Blackleg (stem canker) caused by the fungus Leptosphaeria maculans is one of the most damaging diseases of oilseed rape (Brassica napus). Crop relatives represent a valuable source of "new" resistance genes that could be used to diversify cultivar resistance. B. rapa, one of the progenitors of B. napus, is a potential source of new resistance genes. However, most of the accessions are heterozygous so it is impossible to directly detect the plant genes conferring specific resistance due to the complex patterns of avirulence genes in L. maculans isolates. We developed a strategy to simultaneously characterize and introgress resistance genes from B. rapa, by homologous recombination, into B. napus. One B. rapa plant resistant to one L. maculans isolate was used to produce B. rapa backcross progeny and a resynthesized B. napus plant from which a population of doubled haploid lines was derived after crossing with natural B. napus. We then used molecular analyses and resistance tests on these populations to identify and map the resistance genes and to characterize their introgression from B. rapa into B. napus. Three specific genes conferring resistance to L. maculans (Rlm1, Rlm2 and Rlm7) were identified in B. rapa. Comparisons of genetic maps showed that two of these genes were located on the R7 linkage group, in a region homologous to the region on linkage group N7 in B. napus, where these genes have been reported previously. The results of our study offer new perspectives for gene introgression and cloning in Brassicas.

Cellular localization of endothelin-1 and increased production in liver injury in the rat: potential for autocrine and paracrine effects on stellate cells.

Endothelin (ET) peptides have been implicated in the pathogenesis of several biological processes within the liver. ET levels are elevated in the circulation of patients with cirrhosis, and recent data suggest that ET may be overproduced in the liver itself in this condition. The aims of the current study were to elucidate the cellular source and expression of endothelin-1 (ET-1) in normal and injured liver, and to investigate its biological effects on stellate cells, the primary target of ETs in the liver. In normal hepatic cells, preproET-1 messenger RNA (mRNA) was detected in only nonparenchymal cells, predominantly in sinusoidal endothelial cells. After biliary fibrosis and early cirrhosis induced by bile duct ligation, preproET-1 mRNA and immunoreactive ET levels increased with progressive injury in whole liver extracts, as well as in isolated stellate and endothelial cell fractions. Eight days after bile duct ligation, the relative increase in preproET-1 mRNA was 1.6- and 7.6-fold above normal in sinusoidal endothelial and stellate cells, respectively. Additionally, immunoreactive ET peptide levels increased by 60% +/- 27% over basal values in sinusoidal endothelial cells and 98% +/- 40% in stellate cells. Cultured stellate cells responded dramatically to exogenous ET-1 by the spreading and up-regulation of smooth muscle alpha actin expression. Furthermore, in early culture before cellular activation, ET-1 (10 nmol/L) caused over a twofold increase in [3H]thymidine incorporation, while activated cells (i.e., those cultured for >1 week) exposed to ET-1 exhibited up to a fivefold decrease in [3H]thymidine incorporation. The data indicate that not only is ET-1 overproduced by both sinusoidal endothelial and stellate cells during liver injury, but that it also has potent effects on features of stellate cell activation. We conclude that autocrine and paracrine production of ET-1 is prominent and is likely to be important in the pathogenesis of hepatic diseases.

Diagnostic evaluation for infectious etiology of sickle cell pain crisis.

Occult infections during sickle cell pain crisis can be associated with significant morbidity. It has been suggested that empiric workup for pneumonia and urinary tract infection (UTI) is required. A study was undertaken to determine whether clinical criteria can be used to exclude such infections as precipitants of pain crisis in adults. This retrospective, observational clinical study was conducted in an inner-city teaching hospital emergency department (ED) with 95,000 visits/year. Patients 18 years of age or older presenting to the ED with sickle cell pain crisis who had not used antipyretics within 6 hours before presentation were eligible. Ninety-four visits were evaluated. During initial evaluation the treating physician completed a questionnaire addressing systemic, pulmonary, and urinary tract signs and symptoms. Temperature and physical examination were recorded on an ED memo. Treatment modalities were at the discretion of the treating physician. All patients had a complete blood count, reticulocyte count, urinalysis, and chest radiograph. If the urinalysis was positive (>2 white blood cells) or the patient had clinical evidence of a UTI, a urine culture was obtained. UTI was confirmed through a urine culture with >100,000 colony-forming units/mL. Chest X-rays were reviewed by a staff radiologist. Definitive diagnosis of pneumonia was made by the presence of an infiltrate and a positive clinical response to antibiotic therapy. Thirty-eight patients totalling 94 visits to the ED were studied during an 18-month period. Six diagnoses of pneumonia and 3 diagnoses of UTI were made. All six patients with pneumonia had at least 4 of the signs and symptoms including fever, chills, cough, shortness of breath, sputum production, chest pain, hemoptysis, abnormal pulmonary examination, and temperature of >37.8 degrees C. Of the three patients with UTI, two had signs and symptoms inconsistent with UTI (asymptomatic bacteriuria). In patients with sickle cell pain crisis, medical history and physical examination can be useful to predict the absence of pneumonia, but may not be as beneficial in predicting the absence of UTI. These results suggest that empiric chest x-ray may be unnecessary to exclude pneumonia; however, routine urinalysis may be indicated. Because of the low incidence of these infections, larger studies are required to confirm these findings.

Spontaneous hybridization between a male-sterile oilseed rape and two weeds.

Spontaneous interspecific hybrids were produced under natural conditions (pollination by wind and bees) between a male-sterile cybrid Brassica napus (AACC, 2n = 38) and two weeds Brassica adpressa (AdAd, 2n = 14) and Raphanus raphanistrum (RrRr, 2n = 18). After characterization by chromosome counts and isozyme analyses, we observed 512 and 3 734 inter-specific seeds per m(2) for the B. napus-B. adpressa and B. napus-R. raphanistrum trials respectively. Most of the hybrids studied had the expected triploid structure (ACX). In order to quantify the frequency of allosyndesis between the genomes involved in the hybrids, their meiotic behavior was compared to a haploid of B. napus (AC). For the B. napus-B. adpressa hybrids, we concluded that probably no allosyndesis occurred between the two parental genomes, and that genetic factors regulating homoeologous chromosome pairing were carried by the B. adpressa genome. For the B. napus-R. raphanistrum hybrids, high chromosome pairing and the presence of multivalents (in 9.16% of the pollen mother cells) indicate that recombination is possible between chromosomes of different genomes. Pollen fertility of the hybrids ranged from 0 to 30%. Blackleg inoculation tests were performed on the three parental species and on the interspecific hybrids. BC1 production with the weeds and with rapeseed was attempted. Results are discussed in regard to the risk assessment of transgenic rapeseed cultivation, F1 hybrid rapeseed variety production, and rapeseed improvement.

[Spontaneous rupture of an adenoma of the liver during pregnancy]. / Rupture spontanée d'un adénome du foie pendant la grossesse.

Must often reporting to an hepatic subcapsular hemorrhage with pre or true eclampsia, Spontaneous rupture of adenoma of the liver during pregnancy is unusual entity. Very exceptionally cases of rupture of anatomic hepatic lesion underlying had been reported. About a new case, diagnosis, physiopathologic and management problems are approached.

Sequential treatment of a simple pneumothorax.

In a prospective investigation of isolated simple pneumothorax, the treatment of 35 patients with a total of 37 pneumothoraces was studied. A standardized sequential treatment approach was followed for evacuation of the pneumothorax and maintenance of lung reexpansion. The protocol involved catheter placement using a Seldinger technique, aspirations, and documentation of reexpansion by chest radiography and observation. Reaccumulation of air was treated with Heimlich valve attachment to the catheter at intrapleural pressure and further observation. Continued air leak following Heimlich valve attachment was treated with chest catheter suction using a Pleurovac at -20 cm H2O pressure. Chest tube thoracostomy was performed for continued failure of reexpansion. In 22 of the 37 pneumothoraces (59%) simple catheter aspiration maintained lung reexpansion without complications. In the remaining 15 pneumothoraces (41%), seven (47%) responded to Heimlich valve attachment, and three (20%) maintained expansion with chest catheter suction. Chest tube thoracotomy was required to maintain expansion in 33% (five) of those who failed catheter suction (14% of all pneumothoraces studied). Patients treated successfully with simple catheter aspiration were sent home. Patients requiring a Heimlich valve, chest catheter suction, or chest tube thoracostomy were hospitalized. Use of these catheter techniques resulted in lower cost and was associated with shorter hospitalizations than in chest tube thoracostomy. Our study suggests that sequential treatment of simple pneumothorax should be considered as a cost-effective and therapeutically successful alternative to immediate chest thoracostomy in selected cases.

Influences of the early olfactory environment on the survival, behavior and pituitary-adrenal activity of caesarean delivered preterm rat pups.

In a first experiment, vaginally delivered Day 21 and Caesarean delivered Day 20 and Day 21 rat pups were isolated in the presence of various odorants or no odorant for 1 hr immediately following birth. For Day 20 pups, exposure to novel mint odor resulted in higher mortality during isolation than did exposure to the odor of amnion/placenta. In the preterm pups, whole body corticosterone levels were higher in all isolation treatments than they were immediately following birth. For Day 21 pups, isolation treatments had no effect on corticosterone concentrations, but overall, corticosterone levels were higher following Caesarean section than they were following vaginal delivery. A second experiment replicated the mint odor-induced increase in mortality and revealed a lower activity level in preterm pups exposed to mint odor than in those exposed to the odor of amnion/placenta. Mechanical movement of the pups during exposure eliminated the effects of mint odor on mortality and activity. There was a positive correlation between corticosterone concentrations and pup activity during isolation. These results demonstrate potent influences of seemingly minor changes in early sensory stimulation on the preterm pup. The paradigm might provide a useful animal model for studying the effects of variations in ambient stimulation on premature infants.

[Ankylosing spondylarthritid and Berger's disease. A fortuitous association?]. / Spondylarthrite ankylosante et maladie de berger. Une association fortuite?

Fifteen cases of ankylosing spondylarthritis, associated to an IgA nephropathy have been reported in the literature. This association may be fortuitous, or on the contrary suggest a common pathogenic link between the two diseases and the authors have compared the incidence of radiological abnormalities of the sacro-iliac joints as well as the incidence of rheumatoid clinical signs in 186 patients suffering from an IgA nephropathy to those observed in 192 reference patients. This study could not demonstrate any difference between the two groups and, therefore, suggests that the cases reported in the literature are secondary to a simple fortuitous association.