Pharmacokinetic Model for Cefuroxime Dosing during Cardiac Surgery under Cardiopulmonary Bypass.

Cefuroxime (CXM) is an antibiotic recommended for surgical site infection prevention in cardiac surgery. However, the dosing regimens commonly used do not sustain therapeutic concentrations throughout surgery. The aim of this study was to conduct a population analysis of CXM pharmacokinetics (PK), and to propose an optimized dosing regimen. Adult patients undergoing cardiac surgery under cardiopulmonary bypass (CPB) received a 1,500 mg CXM intravenous bolus followed by a 750 mg bolus at CPB priming, then every 2 h thereafter. Model-based PK simulations were used to develop an optimized dosing regimen and evaluate its efficacy in attaining various concentration thresholds, including those recommended in US and European guidelines. In total, 447 CXM measurements were acquired in 50 patients. A two-compartment model best fit the data, with total body weight and creatinine clearance determining interpatient variability in the central and peripheral volumes of distribution, and in elimination clearance, respectively. Using our optimized dosing regimen, different dosing schemes adapted to body weight and renal function were calculated to attain total concentration thresholds ranging from 12 to 96 mg/liter. Our simulations showed that the dosing regimens recommended in US and European guidelines failed to maintain concentrations above 48 mg/liter. Our individualized dosing strategy was capable of ensuring therapeutic CXM concentrations conforming to each target threshold. Our model yielded an optimized CXM dosing regimen adapted to body weight and renal function, and sustaining therapeutic concentrations consistent with each desired threshold. The optimal target concentration and necessary duration of its maintenance in cardiac surgery still remain unclear.

Reliability of gastric suctioning compared with ultrasound assessment of residual gastric volume: a prospective multicentre cohort study.

We aimed to compare the reliability of aspiration via a nasogastric tube with ultrasound for assessment of residual gastric volume. Sixty-one adult patients who were mechanically ventilated and received continuous enteral feeding through a nasogastric tube for > 48 h were included. A first qualitative and quantitative ultrasound examination of the gastric antrum was followed by gastric suctioning, performed by an operator blinded to the result of the ultrasound examination. A second ultrasound examination was performed thereafter, followed by re-injection of the aspirated gastric contents (≤ 250 ml) into the stomach. A third ultrasound assessment was then immediately performed. If the suctioned volume was ≥ 250 ml, 250 mg erythromycin was infused over 30 min. A fourth ultrasound was performed 90 min after the third. Sixty (98%) patients had a qualitatively assessed full stomach at first ultrasound examination vs. 52 (85%) after gastric suctioning (p = 0.016). The calculated gastric volume significantly decreased after gastric suctioning, without a significant decrease in the number of patients with volume ≥ 250 ml. Four of the nine patients with calculated gastric volume ≥ 250 ml had vomiting within the last 24 h (p = 0.013). The antral cross-sectional area significantly decreased between the third and the fourth ultrasound examination (p = 0.015). Erythromycin infusion did not make a significant difference to gastric volume (n = 10). Our results demonstrate that gastric suctioning is not a reliable tool for monitoring residual gastric volume. Gastric ultrasound is a feasible and promising tool for gastric volume monitoring in clinical practice.

An audit of mammographic screen detected lesions of uncertain malignant potential (B3) diagnosed on initial image guided needle biopsy: how has our practice changed over 10 years?

AIM: To review all cases of B3 lesion diagnosed at initial image-guided needle biopsy over two 5-year cohorts to identify upgrade rates to malignancy and the effect of changing guidance on the management of such lesions. MATERIALS AND METHODS: Data was collected retrospectively. Mammographic features, biopsy type and management were recorded for each lesion. Upgrade rates for each B3 histological category were quantified. Statistical analysis was performed using SPSS. RESULTS: There were 224 cases in 2005-2010 and 240 cases in 2010-2015. Mammographically 211 lesions were microcalcifications, 182 masses, 65 distortions and six asymmetric densities with no difference in the mammographic features in the two cohorts. Two hundred and eight 14 G core biopsies and 256 initial vacuum-assisted biopsies were performed. There was a statistically significant reduction in benign surgical biopsies and an increase in second-line vacuum biopsy/excision in the latter cohort, with no significant change in the upgrade rate. There was an overall 6% upgrade to invasive malignancy and 13% upgrade to ductal carcinoma in situ (DCIS). The upgrade rates for the following histological categories were atypical intraductal epithelial proliferation (AIDEP) 33.2% (21/63); classical (not pleomorphic) in situ lobular neoplasia (ISLN) 18.2% (6/33); flat epithelial hyperplasia (FEA) 21.7% (20/92); papilloma with atypia 53.8% (7/13), without atypia 12.1% (8/66); and radial scar/complex sclerosing lesion with atypia 16.7% (2/12), and without atypia 7.9% (6/76). CONCLUSION: Upgrade rates remain high for some histological categories even with first-line use of vacuum biopsy. Management of borderline lesions should be considered carefully in a multidisciplinary meeting. In many cases, the need for diagnostic surgical excision has been replaced by image-guided vacuum sampling.

Can digital breast tomosynthesis accurately predict whether circumscribed masses are benign or malignant in a screening population?

AIM: To evaluate whether digital breast tomosynthesis (DBT) can predict if circumscribed masses are benign or malignant by assessing margin sharpness. MATERIALS AND METHODS: Circumscribed masses were evaluated on co-registered two-dimensional digital mammography (2DDM) and DBT. Lesions were categorised as follows: category 1=visible sharp border 0-25% of the total margin; category 2 = 26-50% category 3= 51-75%, and category 4=76-100%. Changes in category between 2DDM and DBT were analysed; if the category was lower on DBT the change was negative, if higher the change was positive. RESULTS: Of 759 lesions, 121 masses classified as circumscribed on DBT were included; 25 were malignant and 96 benign. Of the benign lesions, 8/96 were within category 3 or 4 on 2DDM compared with 48/96 benign lesions within category 3 or 4 on DBT (Fisher's exact test p<0.000527). Forty-eight of 51 (94.1%) lesions categorised as 3 or 4 on DBT were benign and 65/67 (97.01%) of the positive category change group were benign. Lesions in category 1 on DBT had 45.4% chance of being malignant (20/44) compared with 22.72% (20/88) on 2DDM (chi-squared test p<0.001). Sixty-five of 67 (97.01%) lesions in the positive category change group were benign and 23/54 (42.6%) lesions with either no or negative category change were malignant. CONCLUSION: The present study demonstrates 97% accuracy in predicting circumscribed lesions as benign when using positive category change and 94% accuracy when >50% of the margin is sharply defined on DBT.

Response of Artemisia herba alba to hexavalent chromium pollution under arid and semi-arid conditions.

The aim of this work is to study and evaluate in situ, the Artemisia herba alba responses to hexavalent chromium stress in the arid and semi-arid steppe Algerian soil. This metallic pollutant was selected to its high toxicity and to its great release from several industrial and agricultural activities emissions in the area of the study region. Artemisia herba alba is a medicinal plant but also a forage species widely used in pasture. It has dominated then adapted to the arid and semi-arid climate of Algerian steppe region, due principally to their morphological and physiological characteristics. To establish this work, A. herba alba species were selected in the Algerian steppe region, and their soils were treated weekly with K2CrO4 solution for about three months. Chromium concentrations were determined in the soil and in the different plants' parts to verify its absorption and translocation with and without pollution simulation. This study demonstrated that A. herba alba has a strong resistance to high concentrations of hexavalent chromium. An increase in chromium concentrations at the different parts of plant's has been noticed, without affecting its growth and vegetative development. The results of physiological and elementary analysis indicated that chromium was absorbed by A. herba alba. Cr (VI) accumulation in plant increase when they are increasing in soil. Translocation factor results indicated that Cr (VI) was mainly accumulated by A. herba alba roots. Particle size analysis showed that the soil is poor in organic substances and mostly sandy loams with 79.77% of sand and 9.76% of clay minerals.

Risk of fracture and low bone mineral density in adults with inflammatory bowel diseases. A systematic literature review with meta-analysis.

Inflammatory bowel diseases (IBDs) are associated with a decreased bone mineral density, but the impact on fractures is unknown. In our study, global risk of fracture is increased for patients with IBDs versus controls. This result will help to determine the appropriate assessment with early screening and management of osteoporosis. Inflammatory bowel diseases (IBDs), such as Crohn's disease (CD) and ulcerative colitis (UC), are associated with a decreased bone mineral density (BMD). However, the impact on fracture risk is unknown and data are contradictory across studies. In this systematic review and meta-analysis, we aimed to assess the risk of fracture and presence of low BMD in patients with IBDs compared to healthy controls. A systematic search of literature was conducted of MEDLINE, EMBASE, the Cochrane library and abstracts from appropriate scientific congresses. Studies were selected if they compared the incidence of fractures and/or BMD measurement by dual-energy X-ray absorptiometry in patients with IBDs and healthy sex- and age-matched controls. Data were extracted by two independent investigators. Meta-analysis was performed with the inverse variance approach to estimate pooled odds ratios (ORs) and risk ratios (RRs) with their 95% confidence intervals (CIs). Twenty-four studies met the inclusion criteria. On the basis of nine studies, global risk of fracture was increased for patients with IBDs versus controls (RR = 1.38, 95% CI 1.11-1.73; p = 0.005). Fracture risk with IBDs was significantly increased for vertebral fractures (OR = 2.26, 95% CI 1.04-4.90; p < 0.001), but not for any other site. The analysis of 16 studies evaluating BMD showed a significant decrease in mean BMD and Z-scores for IBD patients versus controls at all sites. In our meta-analysis, patients with IBDs have an increased risk of fractures, especially in the spine, and significant decreased BMD at all sites, which suggests the need for identifying high-risk individuals among this population.

Several wall-associated kinases participate positively and negatively in basal defense against rice blast fungus.

BACKGROUND: Receptor-like kinases are well-known to play key roles in disease resistance. Among them, the Wall-associated kinases (WAKs) have been shown to be positive regulators of fungal disease resistance in several plant species. WAK genes are often transcriptionally regulated during infection but the pathways involved in this regulation are not known. In rice, the OsWAK gene family is significantly amplified compared to Arabidopsis. The possibility that several WAKs participate in different ways to basal defense has not been addressed. Moreover, the direct requirement of rice OSWAK genes in regulating defense has not been explored. RESULTS: Here we show using rice (Oryza sativa) loss-of-function mutants of four selected OsWAK genes, that individual OsWAKs are required for quantitative resistance to the rice blast fungus, Magnaporthe oryzae. While OsWAK14, OsWAK91 and OsWAK92 positively regulate quantitative resistance, OsWAK112d is a negative regulator of blast resistance. In addition, we show that the very early transcriptional regulation of the rice OsWAK genes is triggered by chitin and is partially under the control of the chitin receptor CEBiP. Finally, we show that OsWAK91 is required for H2O2 production and sufficient to enhance defense gene expression during infection. CONCLUSIONS: We conclude that the rice OsWAK genes studied are part of basal defense response, potentially mediated by chitin from fungal cell walls. This work also shows that some OsWAKs, like OsWAK112d, may act as negative regulators of disease resistance.

Identification of genes regulating TRAIL-induced apoptosis in rheumatoid arthritis fibroblasts-like synoviocytes.

We previously described that sensitivity to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis varied in rheumatoid arthritis fibroblasts-like synoviocytes (RAFLS) from one patient to another and was correlated with disease severity. Therefore, we screened for genes differentially expressed in RAFLS sensitive and resistant to TRAIL-induced apoptosis. The sensitivity of RAFLS was defined based on the percentage of TRAIL-induced apoptosis: 0-10% for resistant cells and >25% for sensitive RAFLS. We performed transcriptomic comparison between RAFLS-S (n=6) and RAFLS-R (n=6) and then examined the implication of identified candidates in the regulation of apoptosis using small interference RNA (siRNA). Microarray analysis revealed 10 functional genes differentially expressed according to TRAIL sensitivity. These factors are implicated in different functions, such as the respiratory chain (ND3), the transport of lipids (OSBP2, PLTP), the regulation of signaling linked to extracellular factors (SULF2, GALNT1, SIAE) or the regulation of gene expression (TET2 and LARP6). We confirmed differential expression for GALNT1 and LARP6 by quantitative reverse transcriptase-PCR. Using siRNA extinction, we demonstrated the implication of GALNT1, SULF2 and LARP6 in the control of TRAIL-induced responses. These results are of particular interest as GALNT1 and LARP6 have been implicated in the regulation of cell death and may represent interesting targets to induce apoptosis of RAFLS.

Factors influencing the Zn and Mn extraction from pyrometallurgical sludge in the steel manufacturing industry.

In this laboratory study, a process has been developed for selectively leaching zinc and manganese from pyrometallurgical sludge produced in the steel manufacturing industry. In the first part, the yield of Zn extraction was studied using four factors and four levels of the Box-Behnken response surface design. The optimum conditions for the step of Zn leaching were determined to be a sulfuric acid concentration of 0.25 mol/L, a pulp density of 10%, an extraction temperature of 20 °C, and three stages of leaching. Under such conditions, 75% of the Zn should be leached. For Mn leaching, the optimum conditions were determined to be a sulfuric acid concentration of 0.25 mol/L, a Na2S2O5/Mn stoichiometry of 1, a leaching time of 120 min and two leaching steps. In this case, 100% of the Mn should be leached.

The accuracy of digital breast tomosynthesis compared with coned compression magnification mammography in the assessment of abnormalities found on mammography.

AIM: To compare the diagnostic accuracy of the digital breast tomosynthesis (DBT) with coned compression magnification mammography (CCMM). MATERIALS AND METHODS: The study design included two reading sessions completed by seven experienced radiologists. In the first session, all readers read bilateral standard two-view mammograms and a CCMM view of the lesion before giving a combined score for assessment. In the second session, readers read bilateral standard two-view mammograms plus one-view DBT. The two reading sessions of the experiment were separated by at least 2 weeks to reduce the chance of reader memory of the images read in the previous session from influencing the performance in the subsequent session. RESULTS: Three hundred and fifty-four lesions were assessed and receiver-operative characteristic (ROC) analysis was used to evaluate the difference between the two modes. For standard two-view mammography plus CCMM, the area under the curve (AUC) was 0.87 [95% confidence interval (CI): 0.83-0.91] and for standard two-view mammography plus DBT the AUC was 0.93 (95% CI: 0.91-0.95). The difference between the AUCs was 0.06 with p-value of 0.0014. CONCLUSION: Two-view mammography with one-view DBT showed significantly improved accuracy compared to two-view mammography and CCMM in the assessment of mammographic abnormalities. These results show that DBT can be used effectively in the further evaluation of mammographic abnormalities found at screening and in symptomatic diagnostic practice.

Tissue near infra red spectroscopy change is not correlated with patients' outcome in elective cardiac surgery.

BACKGROUND: Microcirculatory disturbances following cardiac surgery with cardiopulmonary bypass (CPB) are thought to be at the origin of organ dysfunction, although few studies have correlated microvascular alterations with outcome. We aimed to assess the microcirculation with near infrared spectroscopy (NIRS) and correlate NIRS parameters with intensive care length of stay and organ dysfunction. METHODS: Forty patients at increased risk of postoperative systemic inflammatory response syndrome after an elective cardiac surgery with CPB were included in this prospective observational study. Microcirculation of the thenar eminence was analysed by NIRS technology, through the tissue oxygen saturation (StO2 ) and the recovery slope after an ischaemic challenge. Organ dysfunction was assessed with the Sequential Organ Failure Assessment (SOFA) score. Microcirculation parameters were recorded at baseline, at different time points during the surgery and the first 48 postoperative hours. RESULTS: StO2 at baseline was 82% and decreased significantly until 77% at 2 h after CPB. Recovery slope values were 4.3% per second at baseline and decreased to 2.5% per second during CPB (P < 0.05). From 12 h after CPB time point, both parameters were not statistically different from baseline anymore. We found no correlation between microcirculatory parameters and mean arterial pressure, cardiac index, intensive care unit (ICU) length of stay or SOFA score. CONCLUSION: This study confirms, through a non-invasive technology, a significant but transient alteration of the microcirculation during elective cardiac surgery. However, as these microvascular alterations were not correlated with patient's outcome, NIRS-derived parameters seem to be of limited interest in the cardiac surgery setting.

Neutron source reconstruction using a generalized expectation-maximization algorithm on one-dimensional neutron images from the Z facility.

Magnetized Liner Inertial Fusion experiments have been performed at the Z facility at Sandia National Laboratories. These experiments use deuterium fuel, which produces 2.45 MeV neutrons on reaching thermonuclear conditions. To study the spatial structure of neutron production, the one-dimensional imager of neutrons diagnostic was fielded to record axial resolved neutron images. In this diagnostic, neutrons passing through a rolled edge aperture form an image on a CR-39-based solid state nuclear track detector. Here, we present a modified generalized expectation-maximization algorithm to reconstruct an axial neutron emission profile of the stagnated fusion plasma. We validate the approach by comparing the reconstructed neutron emission profile to an x-ray emission profile provided by a time-integrated pinhole camera.

[Infections in primary Sjögren's syndrome patients: "Real-life" study of 109 patients from Montpellier university hospital]. / Infections rapportées chez 109 patients avec syndrome de Gougerot-Sjögren primaire suivis au CHU de Montpellier.

INTRODUCTION: Infections are responsible for a part of the overall mortality in primary Sjögren's syndrome patients (pSS). Our retrospective monocentric study aimed at describing infections reported in a population of pSS hospitalized patients, along with the characteristics of their disease. METHODS: Patients with SS have been randomly selected from our hospital database claim, between 2009 and 2018. After careful analysis of their medical chart, only patients with pSS and fulfilling ACR/EULAR 2016 diagnosis criteria were included. We collected main clinical, biological and pathological characteristics of SS, along with all the reported infections during the follow-up. The characteristics of the disease were compared according to the presence of an infection in hospitalization. RESULTS: In total, 109 pSS patients were included (93% of women, mean age 53.6±14.3 years, mean follow-up 8.2±8.4 years). Fifty-one percent had been exposed to hydroxychloroquine (HCQ). Seventy-eight infections were recorded in 47 (43%) patients. Twenty-five infections were recorded in hospitalization (5 in critical care) in 20 (18%) patients, whom leading causes were urinary tract (28%), pulmonary (24%), ENT (16%), and intestinal (12%) infections. pSS patients with infections in hospitalization were older, exhibited more hypocomplementemia, and were less exposed to HCQ. We found no difference in immunosuppressive treatments exposure. CONCLUSIONS: The impact of HCQ exposure on infectious risk needs further investigations. Broad vaccination campaign and tight control of sicca syndrome could lead to a better control of infection risk.

Drug-specific risk of non-tuberculosis opportunistic infections in patients receiving anti-TNF therapy reported to the 3-year prospective French RATIO registry.

BACKGROUND: Anti-tumour necrosis factor (TNF) therapy may be associated with opportunistic infections (OIs). OBJECTIVE: To describe the spectrum of non-tuberculosis OIs associated with anti-TNF therapy and identify their risk factors. METHODS: A 3-year national French registry (RATIO) collected all cases of OI in patients receiving anti-TNF treatment for any indication in France. A case-control study was performed with three controls treated with anti-TNF agents per case, matched for gender and underlying inflammatory disease. RESULTS: 45 cases were collected of non-TB OIs in 43 patients receiving infliximab (n=29), adalimumab (n=10) or etanercept (n=4) for rheumatoid arthritis (n=26), spondyloarthritides (n=3), inflammatory colitis (n=8), psoriasis (n=1) or other conditions (n=5). One-third (33%) of OIs were bacterial (4 listeriosis, 4 nocardiosis, 4 atypical mycobacteriosis, 3 non-typhoid salmonellosis), 40% were viral (8 severe herpes zoster, 3 varicella, 3 extensive herpes simplex, 4 disseminated cytomegalovirus infections), 22% were fungal (5 pneumocystosis, 3 invasive aspergillosis, 2 cryptococcosis) and 4% were parasitic (2 leishmaniasis). Ten patients (23%) required admission to the intensive care unit, and four patients (9%) died. Risk factors for OIs were treatment with infliximab (OR=17.6 (95% CI 4.3 - 72.9); p<0.0001)or adalimumab (OR=10.0 (2.3 to 44.4); p=0.002) versus etanercept, and oral steroid use >10 mg/day or intravenous boluses during the previous year (OR=6.3 (2.0 to 20.0); p=0.002). CONCLUSION: Various and severe OIs, especially those with intracellular micro-organisms, may develop in patients receiving anti-TNF treatment. Monoclonal anti-TNF antibody rather than soluble TNF receptor therapy and steroid use >10 mg/day are independently associated with OI.

Haemodynamic consequences of etomidate administration in elective cardiac surgery: a randomized double-blinded study.

BACKGROUND: The consequences of inhibition of cortisol synthesis by a single dose of etomidate on subsequent vasopressor drug usage and the duration of relative adrenal insufficiency (RAI) after cardiac surgery are not known. METHODS: This was a prospective, randomized, double-blinded controlled trial of 100 patients undergoing elective cardiac surgery and receiving either etomidate or propofol at induction of anaesthesia. A short corticotropin test was performed 12, 24, and 48 h after anaesthesia induction. RAI was defined as a response <250 nmol litre(-1). RESULTS: The mean (sd) norepinephrine infusion rate during the first 48 postoperative hours was 0.11 (0.01) and 0.11 (0.01) µg kg(-1) min(-1) in the etomidate and propofol groups, respectively (P=0.89). Time to norepinephrine withdrawal was similar between the groups. The incidence of RAI was higher in the etomidate group at 12 h (100% vs 41%, P<0.001) and 24 h (85% vs 25%, P<0.001). CONCLUSIONS: A single bolus of etomidate blunts the hypothalamic-pituitary-adrenal axis response for more than 24 h in patients undergoing elective cardiac surgery, but this was not associated with an increase in vasopressor requirements.

Mechanical ventilation preserves diaphragm mitochondrial function in a rat sepsis model.

BACKGROUND: To describe the effect of mechanical ventilation on diaphragm mitochondrial oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and cytochrome c oxidase activity and content, and their relationship to diaphragm strength in an experimental model of sepsis. METHODS: A cecal ligation and puncture (CLP) protocol was performed in 12 rats while 12 controls underwent sham operation. Half of the rats in each group were paralyzed and mechanically ventilated. We performed blood gas analysis and lactic acid assays 6 h after surgery. Afterwards, we measured diaphragm strength and mitochondrial oxygen consumption, ATP and ROS generation, and cytochrome c oxidase activity. We also measured malondialdehyde (MDA) content as an index of lipid peroxidation, and mRNA expression of the proinflammatory interleukin-1ß (IL-1ß) in diaphragms. RESULTS: CLP rats showed severe hypotension, metabolic acidosis, and upregulation of diaphragm IL-1ß mRNA expression. Compared to sham controls, spontaneously breathing CLP rats showed lower diaphragm force and increased susceptibility to fatigue, along with depressed mitochondrial oxygen consumption and ATP production and cytochrome c oxidase activity. These rats also showed increased mitochondrial ROS generation and MDA content. Mechanical ventilation markedly restored mitochondrial oxygen consumption and ATP production in CLP rats; lowered mitochondrial ROS production by the complex 3; and preserved cytochrome c oxidase activity. CONCLUSION: In an experimental model of sepsis, early initiation of mechanical ventilation restores diaphragm mitochondrial function.

Preformed expression of defense is a hallmark of partial resistance to rice blast fungal pathogen Magnaporthe oryzae.

BACKGROUND: Partial resistance to plant pathogens is extensively used in breeding programs since it could contribute to resistance durability. Partial resistance often builds up during plant development and confers quantitative and usually broad-spectrum resistance. However, very little is known on the mechanisms underlying partial resistance. Partial resistance is often explained by poorly effective induction of plant defense systems. By exploring rice natural diversity, we asked whether expression of defense systems before infection could explain partial resistance towards the major fungal pathogen Magnaporthe oryzae. The constitutive expression of 21 defense-related genes belonging to the defense system was monitored in 23 randomly sampled rice cultivars for which partial resistance was measured. RESULTS: We identified a strong correlation between the expression of defense-related genes before infection and partial resistance. Only a weak correlation was found between the induction of defense genes and partial resistance. Increasing constitutive expression of defense-related genes also correlated with the establishment of partial resistance during plant development. Some rice genetic sub-groups displayed a particular pattern of constitutive expression, suggesting a strong natural polymorphism for constitutive expression of defense. Constitutive levels of hormones like salicylic acid and ethylene cannot explain constitutive expression of defense. We could identify an area of the genome that contributes to explain both preformed defense and partial resistance. CONCLUSION: These results indicate that constitutive expression of defense-related genes is likely responsible for a large part of partial resistance in rice. The finding of this preformed defense system should help guide future breeding programs and open the possibility to identify the molecular mechanisms behind partial resistance.

Sodium channel Na(V)1.5 expression is enhanced in cultured adult rat skeletal muscle fibers.

This study analyzes changes in the distribution, electrophysiological properties, and proteic composition of voltage-gated sodium channels (Na(V)) in cultured adult rat skeletal muscle fibers. Patch clamp and molecular biology techniques were carried out in flexor digitorum brevis (FDB) adult rat skeletal muscle fibers maintained in vitro after cell dissociation with collagenase. After 4 days of culture, an increase of the Na(V)1.5 channel type was observed. This was confirmed by an increase in TTX-resistant channels and by Western blot test. These channels exhibited increased activation time constant (tau(m)) and reduced conductance, similar to what has been observed in denervated muscles in vivo, where the density of Na(V)1.5 was increasing progressively after denervation. By real-time polymerase chain reaction, we found that the expression of beta subunits was also modified, but only after 7 days of culture: increase in beta(1) without beta(4) modifications. beta(1) subunit is known to induce a negative shift of the inactivation curve, thus reducing current amplitude and duration. At day 7, tau(h) was back to normal and tau(m) still increased, in agreement with a decrease in sodium current and conductance at day 4 and normalization at day 7. Our model is a useful tool to study the effects of denervation in adult muscle fibers in vitro and the expression of sodium channels. Our data evidenced an increase in Na(V)1.5 channels and the involvement of beta subunits in the regulation of sodium current and fiber excitability.

Time course of liver nitric oxide concentration in early septic shock by cecal ligation and puncture in rats.

An overwhelming nitric oxide (NO) production is a crucial step in the circulatory events as well as in the cellular alterations taking place in septic shock. However, evidences of this role arise from studies assessing the NO production on an intermittent basis precluding any clear evaluation of temporal relationship between NO production and circulatory alterations. We evaluated this relationship by using a NO specific electrode allowing a continuous measurement of NO production. Septic shock was induced by a cecal ligation and puncture (CLP) in a first group of anesthetized rats. After the same CLP, a second group received a selective iNOS inhibitor (L-NIL). Control rats were sham operated or sham operated with L-NIL administration. While NO concentration was measured every 2 min by a NO-sensitive electrode over 7h following CLP, the liver microcirculation was recorded by a laser-Doppler flowmeter. CLP induced a severe septic shock with hypotension occurring at a mean time of 240 min after CLP. At the same time, an increase in liver NO concentration was observed, whereas a decrease in microvascular liver perfusion was noted. In the septic shock group, L-NIL administration induced an increase in arterial pressure whereas the liver NO concentration returned to baseline values. In addition, shock groups experienced an increase in iNOS mRNA. These data showed a close temporal relationship between the increase in liver NO concentration and the microvascular alteration taking place in the early period of septic shock induced by CLP. The iNOS isoform is involved in this NO increase.