Clinical, functional, and radiological results of the Amandys® interposition arthroplasty in 13 cases of wrist osteoarthritis

Amandys® pyrocarbon interposition arthroplasty is intended for widespread arthritis of the wrist. The aim of this study was to assess the clinical, functional, and radiological results of this arthroplasty with a minimum follow-up of 12 months. This retrospective single-center study brought together all osteoarthritis indications that can benefit from an Amandys® arthroplasty. Twenty-one implants were used between January 2011 and October 2018. There were seven cases of distal radius malunion, eight SLAC wrists, two SNAC wrists, two cases of Kienböck's disease at Lichtman's stage 4, and two aftermaths of inflammatory arthritis. Twenty-four percent of patients had previously undergone another type of surgery for this wrist arthritis. Six implants were removed, five early for dislocation and one after 6 years for chronic pain. Thirteen patients were reviewed with an average follow-up of 40.7 months (21-90). The average pain level on a visual analog scale was 3.1/10 (0-7). The mean range motion was 36° flexion (10-60) and 33° extension (15-50). The mean grip strength at the last follow-up was 14.8 kg (2-30) (43% of contralateral). The average QuickDASH and PRWE functional scores were 37.9/100 (0-80) and 29.6/100 (0-83.5), respectively. Amandys® interposition arthroplasty is an interesting alternative to total wrist fusion or total wrist prosthesis for widespread arthritis of the wrist. For the implant to be stable, the capsulo-ligamentous systems must be intact.

Stereochemically enriched extractants for the extraction of actinides

Stereoisomers of monoamide highlight the importance of the extractant chirality for U/Pu extraction.

Impact of individual social deprivation on environmental risk perception by French pregnant women

Background

Individual social deprivation (ISD) can have significant impact on the life conditions. However, few studies explored the impact of ISD on the preventive behaviors adopted by pregnant women (PW) in relation to exposure of chemicals.

AIM

This study aims to describe the link between ISD and the perception of chemical and environmental risks.

Methods

A cross-sectional survey was performed among PW present in maternity hospitals in Auvergne (France). Face-to-face interviews with a standardized questionnaire were used to collect anonymously the data (socio-demographic characteristics, smoking behaviors, perception of environmental risks (PER Score based on Likert scale ranking from 0 to 10), individual social deprivation (by EPICES score)). Statistical analysis (univariate analysis - logistic regression) was performed with Modalisa® 8.0 (Kynos, Paris).

Results

300 PW (29±5 years old) were included. The majority of PW reported being aware of the risks associated with chemicals. The PER Score is estimated at 6.3±1.8. It was significantly associated with parity and trimester of pregnancy, and inversely linked to age of PW. The EPICES Score was 19.9 ±17.8 (rank: 0-85). With a precariousness threshold of 30, only a quarter of the PW were in a precarious situation. The EPICES Score was inversely related to age, smoking behaviors, and environmental risks perception. The criterion of choice of everyday products was linked to the EPICES score. 'Organic products' were mainly used by PW with EPICES Score < 30 (not precarious).

Conclusions

The weight of social determinisms on environmental sensitivity highlights the need for targeted prevention. The role of health professionals in prevention and environmental health promotion is essential, especially to detect women of low socioeconomic status who may not be sensitive to media messages and prevention campaigns disseminated by health authorities.

Key messages

Perinatal health professionals must have a major role in environmental health promotion, especially for pregnant women with individual social deprivation. Perception of chemicals and environmental risks was inversely linked to the individual social deprivation (EPICES score) in this French PW population.

THU0084 TOFACITINIB REVERSED ENDOTHELIAL DYSFUNCTION IN RHEUMATOID ARTHRITIS: MECHANISTIC INSIGHTS FROM THE RAT ADJUVANT-INDUCED ARTHRITIS MODEL

Background:

Tofacitinib, an inhibitor of JAK3 and JAK1, is approved for the treatment of rheumatoid arthritis (RA)1. Cardiovascular (CV) risk2and events3in RA patients treated with Tofacitinib is a matter of debate, but the vascular mechanisms involved are unknown.

Objectives:

The aim of this study was to investigate whether Tofacitinib improves endothelial dysfunction (ED) and if so to explore the underlying mechanisms in the model of adjuvant-induced arthritis (AIA) in rats.

Methods:

AIA was induced by injection ofMycobacterium butyricumin the tail of male Lewis rats. A group of rats without arthritis served as controls. At the first signs of arthritis, AIA received Tofacitinib (10 mg/kg twice daily, s.c.) or 33%DMSO/PEG300(Vehicle). Arthritis score was daily evaluated. After 21 days, preconstricted isolated aortic rings were relaxed with acetylcholine (Ach, 10-11-10-4moles/liter) in the presence or not of inhibitor of nitric oxide (NO) synthase (L-NAME), cyclooxygenase-2 (NS398), arginase (nor-NOHA), endothelium-derived hyperpolarizing factor (EDHF) (apamin/charybdotoxin) and superoxide anions production (Tempol). Endothelium-denuded rings were used to determine the vasorelaxant response to the NO-donor sodium nitroprussiate (SNP, 10-11-10-4moles/liter). Blood pressure and heart rate were measured by invasive method. A radiographic score was attributed to hind paws.

Results:

Compared to AIA-Vehicle, Tofacitinib dramatically reduced arthritis (-76%) and radiographic (-73%) scores (p<0.001), and improved Ach-induced vasorelaxation (p<0.05). Of note, Ach-induced vasorelaxation was not different between Tofacitinib-AIA and control rats. The response to SNP was not different between groups. The effect of Tofacitinib on ED was mediated by decreased cyclooxygenase-2 and arginase activities, decreased superoxide anions production, increased NO synthase activity and EDHF synthesis. As compared to AIA-Vehicle, Tofacitinib changed neither blood pressure nor heart rate.

Conclusion:

The present results demonstrated that Tofacitinib reversed arthritis-induced ED, through the correction of all the acknowledged impaired endothelial pathways in the AIA model. As ED is theprimum movensof atherogenesis, these data provide a mechanistic explanation to the potential benefits of Tofacitinib on the cardiovascular comorbidities associated to RA.

References:

[1]Lee EB.et al. Tofacitinib versus methotrexate in rheumatoid arthritis. N Engl J Med. (2014);370:2377-86.

[2]Nurmohamedet al.The Impact of Biologics and Tofacitinib on Cardiovascular Risk Factors and Outcomes in Patients with Rheumatic Disease: A Systematic Literature Review. Drug Saf. (2018);41(5):473-488.

[3]Charles-Schoemanet al. Risk Factors for Major Adverse Cardiovascular Events in Phase III and Long-Term Extension Studies of Tofacitinib in Patients With Rheumatoid Arthritis. Arthritis Rheumatol. (2019);71(9):1450-1459.

Disclosure of Interests:

Perle Totoson: None declared, Clément Prati: None declared, Daniel Wendling: None declared, Aurore Quirié: None declared, Christine Marie: None declared, Céline Demougeot Grant/research support from: With an institutional support from Pfizer.

Cosmetics and pregnancy: perception of health risk by health professionals and pregnant women

Contex

During pregnancy, the International Federation of Gyneco-Obstetrics (FIGO) advocates limiting exposure to chemicals present in everyday products, including cosmetics. However, both pregnant women (PW) and perinatal health professionals (PHP) know still poorly this source of exposure. AIMS: The PERICOS-Quali Study aims to identify the perception of the risk associated with the use of cosmetics during pregnancy by PHP and PW.

Methodology

A qualitative survey was conducted among PHP and PW in Auvergne (France). The data were collected by semi-structured interviews with the PHP and by focus group with the PW, until saturation of the speeches, by an experienced investigator, with an interview guide. The interviews were recorded, the verbatim was transcribed and subjected to a thematic analysis with the N-VIVO v11 software.

Results

12 PHP (5 midwives, 2 general practitioners and 5 obstetricians) and 24 PW were interviewed. PHP and PW considered cosmetics as wellness and body-care products. Furthermore PHP noted that during pregnancy women used more often organic products, moisturizers or anti-stretch marks, and reduced the use of perfumes, deodorants. In the absence of recommandations based on Evidence-Based Medecine, PHP and PW considered the risk related to cosmetics as not major. The PHP (especially midwives) reported giving advice to comfort the pregnant women; their positioning was not to prohibit the use of cosmetics during pregnancy. PW did not identify PHP as reliable sources of information about cosmetics.

Conclusions

PHP are seeking for tools to help them to better advice PW. And PW would like also to have pertinent advices about cosmetics to make a reasoned choice.

Key messages

Health education about use of cosmetics during pregnancy is necessary. Pregnant women and health professionals don’t perceive health risk linked to cosmetics.

Perception of health risk linked to environmental factors by pregnant women

Bacground

Recently, the International Federation of Gyneco-Obstetrics (FIGO) advocates limiting exposure to chemicals present in everyday products during pregnancy. To date, the chemicals, and the risks related, are not well-known, as well by perinatal health professionals (PHP) as by pregnant women (PW). AIMS: to estimate the sensitivity to the environment and the perception of risks related to chemical substances by pregnant women.

Methodology

A descriptive cross-over study was carried out among pregnant women ((followed or hospitalized in different health establishments in Auvergne). The collection of data (socio-demographic characteristics, sensitivity to the environment, use of cosmetics, perception of environmental risks) was carried out by interviewers, using a standardized questionnaire. The statistical analysis (logistic regression) was performed with Modalisa® 8.0 (Kynos, Paris).

Results

Three hundred questionnaires were analyzed. The sensitivity to the environment is estimated at 6.3 ± 1.7 (scale 0 to 10). For the majority of women, exposure to chemicals is primarily related to the use of cleaning products, DIY products, and gardening products. Food can also be a source of exposure (especially for pesticides). On the other hand, cosmetics are not perceived as products containing chemical substances, with potential risk to health. This vision of chemical substances is related to age, educational level, socio-professional category and sensitivity to the environment. Only 5% (19/300) of PW considered health professionals as referents on chemical substances and environmental problems.

Conclusions

This study highlighted the sensitivity of pregnant women to environmental issues, but a lack of knowledge of chemicals and the risks which they represent for health. It is important to reinforce the information given to pregnant women by perinatal health professionals about healthy behaviors.

Key messages

Pregnant women don’t know all sources of exposure to chemical substances. Training in environmental health must be increased for perinatal health professionals.

Variations of Cytokine Levels and Production in CAPD Patients

Macrophages, predominant cells in dialysates of patients on CAPD without peritonitis, produce a wide variety of substances including cytokines. The aim of this study was to examine the cytokine production in five uninfected patients. This work investigated the presence in dialysates of interleukin-1ß, interleukin-6, interleukin-8, tumor necrosis factor α and the ability of peritoneal macrophages to produce these cytokines. These results were compared with values obtained from control group in non-uremic conditions (peritoneal lavage with isotonic saline or dialysis fluid). All cytokines were detectable in dialysates. Interindividual variations in cytokine concentration in dialysates were wider than variations of production of cytokines ex vivo by stimulated and unstimulated cells. In control group, dialysis fluid inhibited the cytokine production and with isotonic saline, cells produced less cytokines than dialysis patients'cells. The highest levels of interleukin-1 and tumor necrosis factor in dialysates and the highest capacity to respond to LPS were observed in patients having the shortest duration of dialysis. The variability observed did not seem to be due to cells themselves but to their environment.

Activation of endothelial TrkB receptors induces relaxation of resistance arteries

While brain-derived neurotrophic factor (BDNF) was previously reported to induce relaxation of conduit artery, whether the BDNF/TrkB (tropomyosin-related kinase) pathway is involved in the tone control of resistance arteries is not known. This study investigated TrkB receptors levels/localization and the vasomotor effect of the TrkB receptor agonist LM22A-4 in isolated third-order mesenteric arteries from rats. Immunostaining revealed the presence of both full-length and truncated TrkB receptors, especially at the endothelial level. By using wire myography, LM22A-4 induced vascular relaxation that was significantly decreased by cyclotraxin B as a non-competitive TrkB antagonist and fully prevented by endothelium removal. Inhibitors of NO, EDHF, PGI2 production and the PI3K/Akt pathways separately reduced LM22A-4 induced-relaxation. By contrast, inhibition of Raf/MEK, PLCγ and CaM/CaMKII pathways did not change the relaxant effect of LM22A-4. Interestingly, BDNF also induced an endothelium and TrkB-dependent relaxation. These results indicate that endothelial TrkB activation results in the relaxation of resistance vessels via PI3K/Akt-induced eNOS phosphorylation and production of EDHF and PGI₂. These data are consistent with the contribution of the endothelial BDNF/TrkB pathway to the regulation of peripheral vascular tone. They also validate the use of LM22A-4 as a reliable pharmacological agent for studying the vascular effect of BDNF.

ToF-SIMS Depth Profiling of PS-b-PMMA Block Copolymers Using Arn+, C60++, and Cs+ Sputtering Ions

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a high performance tool for molecular depth profiling of polymer films, in particular when they are structured in microphases. However, a major issue is the degradation of polymer materials under ion irradiation in reactions such as cross-linking, chain breaking, or reorganization processes of polymers which have been demonstrated for materials such as polystyrene (PS) and poly(methyl methacrylate) (PMMA). This work aims at comparing ToF-SIMS molecular depth profiling of structured polymers (polystyrene (PS)-b-polymethyl methacrylate (PMMA) block copolymers (BCP)) using either ultralow energy cesium or the more recently introduced C₆₀⁺⁺ (under NO dosing and with sample cooling) and argon cluster ion beams (using Ar₁₅₀₀⁺ ions at 5 keV). The latter improved the quality of the depth profiles, especially the argon cluster ion beam, as it is characterized by a greater homogeneity for the sputter yields of PS and PMMA. No significant artifacts were observed, and this was confirmed by the comparison of depth profiles obtained from films with variable thickness, annealing time, and morphology (cylindrical blocks vs spherical blocks). Comparison to a theoretical model (hexagonal centered pattern) ensured that the ToF-SIMS depth profiles described the real morphology and may thus be a relevant characterization tool to verify the morphology of the films as a function of the deposition parameters.

Brain-derived neurotrophic factor of the cerebral microvasculature: a forgotten and nitric oxide-dependent contributor of brain-derived neurotrophic factor in the brain

AIM

Evidence that brain-derived neurotrophic factor (BDNF), a neurotrophin largely involved in cognition, is expressed by cerebral endothelial cells led us to explore in rats the contribution of the cerebral microvasculature to BDNF found in brain tissue and the link between cerebrovascular nitric oxide (NO) and BDNF production.

METHODS

Brain BDNF protein levels were measured before and after in situ removal of the cerebral endothelium that was achieved by brain perfusion with a 0.2% CHAPS (3-[(3-cholamidopropyl) dimethylammonio]-1-propane sulphonate) solution. BDNF protein and mRNA levels as well as levels of endothelial NO synthase phosphorylated at serine 1177 (P-eNOS^ser1177 ) were measured in cerebral microvessel-enriched fractions. These fractions were also exposed to glycerol trinitrate. Hypertension (spontaneously hypertensive rats) and physical exercise training were used as experimental approaches to modulate cerebrovascular endothelial NO production.

RESULTS

CHAPS perfusion resulted in a marked decrease in brain BDNF levels. Hypertension decreased and exercise increased P-eNOS^ser1177 and BDNF protein levels. However, BDNF mRNA levels that were increased by exercise did not change after hypertension. Finally, in vitro exposure of cerebral microvessel-enriched fractions to glycerol trinitrate enhanced BDNF production.

CONCLUSION

These data reveal that BDNF levels measured in brain homogenates correspond for a large part to BDNF present in cerebral endothelial cells and that cerebrovascular BDNF production is dependent on cerebrovascular endothelial eNOS activity. They provide a paradigm shift in the cellular source of brain BDNF and suggest a new approach to improve our understanding of the link between endothelial function and cognition.

Glucocorticoids improve endothelial function in rheumatoid arthritis: a study in rats with adjuvant-induced arthritis

To determine the effect of glucocorticoids (GCs) on endothelial dysfunction (ED) and on traditional cardiovascular (CV) risk factors in the adjuvant-induced arthritis (AIA) rat model. At the first signs of AIA, a high dose (HD) [10 mg/kg/day, intraperitoneally (i.p.), GC-HD] or low dose (LD) (1 mg/kg/day, i.p., GC-LD) of prednisolone was administered for 3 weeks. Endothelial function was studied in aortic rings relaxed with acetylcholine (Ach) with or without inhibitors of nitric oxide synthase (NOS), cyclooxygenase 2 (COX-2), arginase, endothelium derived hyperpolarizing factor (EDHF) and superoxide anions ( O2-°) production. Aortic expression of endothelial NOS (eNOS), Ser1177-phospho-eNOS, COX-2, arginase-2, p22^phox and p47^phox was evaluated by Western blotting analysis. Arthritis scores, blood pressure, heart rate and blood levels of cytokines, triglycerides, cholesterol and glucose were measured. GC-HD but not GC-LD reduced arthritis score significantly and improved Ach-induced relaxation (P < 0·05). The positive effect of GC-HD resulted from increased NOS activity and EDHF production and decreased COX-2/arginase activities and O2-° production. These functional effects relied upon increased phospho-eNOS expression and decreased COX-2, arginase-2 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expression. Despite the lack of effect of GC-LD on ED, it increased NOS and EDHF and down-regulated O2-° pathways but did not change arginase and COX-2 pathways. GC-HD increased triglycerides levels and blood pressure significantly (P < 0·05). Both doses of GCs decreased to the same extent as plasma interleukin (IL)-1β and tumour necrosis factor (TNF)-α levels (P < 0·05). Our data demonstrated that subchronic treatment with prednisolone improved endothelial function in AIA via pleiotropic effects on endothelial pathways. These effects occurred independently of the deleterious cardiometabolic effects and the impact of prednisolone on systemic inflammation.

CD14/LPS receptor exhibits lectin-like properties

We had previously shown that the specific binding of endotoxin (lipopolysaccharide, LPS) to human monocytes in the presence of serum was mediated by the polysaccharide moiety of the LPS molecule. CD14 has been identified as the main receptor for endotoxin on monocytes/macrophages. In the present report we demonstrate that the CD14 molecule exhibits lectin-like properties. Anti-CD14 monoclonal antibodies inhibited the binding of [3H]-radiolabeled Neisseria meningitidis LPS as efficiently as the homologous unlabeled LPS. Rough Escherichia coli LPS (Rc- and Re-types) could also inhibit the binding of [3H]-LPS to a similar extent, whereas lipid A had no or very weak inhibitory activity. This suggests a major contribution of the inner-core region within the LPS and particularly the Kdo sugars. The lectin-like nature of CD14 was assessed with polyanionic sugars as well as with uncharged polysaccharides. The relative efficiencies in competition were dextran sulfate > fucoidan > mannan > polygalacturonic acid = heparan sulfate ≥ heparin ≥ chondroitin sulfate. Candida albicans phospholipomannan was far more active in the competition experiment than the mannan, indicating that, besides the osidic residues, anionic charges and/or fatty acids may contribute to the interaction with the CD14 molecule. Binding of polysaccharide to CD14 was not sufficient to trigger TNFα and IL-6 production since phospholipomannan and dextran sulfate were unable to induce cytokine release. Taken together, these results demonstrate that the binding of [3H]-LPS to CD14 involves the contribution of sugars and suggest that the signals for cytokine production require additional interactions.

Ischaemic stroke subtypes and associated risk factors: a French population based study

BACKGROUND

There is little reliable population based information about the distribution of risk factors among the various ischaemic stroke subtypes, even though determining risk factor profiles is of major importance to develop targeted preventive strategies.

METHODS

The distribution of first ever ischaemic stroke subtypes was established in a prospective population based study conducted in Dijon, France (152,606 inhabitants). Cases were collected between January 2005 and December 2006, and were classified using TOAST classification. Vascular risk factors were recorded to determine a risk factor profile for each subtype.

RESULTS

332 patients with first ever ischaemic stroke (150 men and 182 women) were recorded. Adjusted incidence to world population was 54/100,000/year. The distribution of ischaemic stroke subtypes was as follows: 119 (35.8%) cases of large artery atherosclerosis, 89 (26.8%) small artery occlusions, 81 (24.4%) cardioembolisms and 43 (13%) other and undetermined causes. The most frequent vascular risk factor was hypertension, irrespective of the ischaemic stroke subtype, with a total prevalence of 62%. Using multivariate regression, a positive association between cardioembolism and age (OR 1.051; 95% CI 1.026 to 1.076; p<0.001) was demonstrated and between small artery occlusion and either high blood pressure (OR 1.86; 95% CI 1.06 to 3.27; p = 0.03) or hypercholesterolaemia (OR 2.23; 95% CI 1.33 to 3.76; p = 0.02).

CONCLUSION

This comprehensive prospective population based study has demonstrated that vascular risk factors exhibit a particular distribution according to the ischaemic stroke subtypes. These findings, as well as the great frequency of hypertension among stroke patients, have implications for prevention strategies, the design of clinical trials and the organisation of health care services.

HLA, NFKB1 and NFKBIA Gene Polymorphism Profile in Autoimmune Diabetes Mellitus Patients

Type 1 diabetes mellitus (T1DM) is one of the long-time studied autoimmune disorders. The triggering of the autoimmune process has been ascribed to various genes active in the regulation of the cytokine gene transcription including the Rel/NF-kappaB gene family. In our study the gene polymorphism of HLA class II, NFKB1 (nuclear factor of kappa light polypeptide gene enhancer in B-cells 1) and NFKBIA (inhibitor of nuclear factor kappa B) was tested. Patients were divided into the subgroups in relation to the disease type: T1DM in children, T1DM in adults, and Latent Autoimmune Diabetes in Adults (LADA). HLA-DRB1 (*)04 and HLA-DQB1 (*)0302 have been detected as risk factors for T1DM in adults and particularly in children (P<0.0001, OR=22.9 and 46.5 respectively). HLA-DRB1 (*)03 has been found as a single risk factor for LADA (P<0.0001, OR=4.9). We detected 15 alleles for the NFKB1 gene polymorphism (CA-repeats) in the Czech population. The alleles were ranging in size from 114-142 bp corresponding to 10-25 CA repeats. Frequency of the A7 allele of NFKB1 gene has been significantly increased in T1DM adults (P<0.01). There was no difference in A and a G allele frequency of NFKBIA gene between the control group and patients, but the association of the AA genotype of NFKBIA gene has been found for LADA (P<0.05). Summarizing our results we concluded that there is a high probability of association of gene polymorphism from Rel/NF-kappaB family with an autoimmune diabetes course. Due to the results obtained in the epidemiological study we have been looking also for the function significance of the genetic predisposition. No significant changes have been observed by real time PCR testing of HLA-DRB1 (*)04 gene and NFKB1 gene expression between T1DM diabetic group with different HLA, NFKB1, NFKBIA genetic background.

Effect of early decrease in the lesion size on late brain tissue loss, synaptophysin expression and functionality after a focal brain lesion in rats

The purpose of the present study is to determine the effects of early decrease in the lesion size on late brain tissue loss, synaptogenesis and functionality after a focal brain lesion in rats. The lesion was induced either to the cortex using the photothrombotic ischemic stroke or to the striatum using the malonate poisoning model. The cortical and striatal lesions amounted to 66-80 mm(3) at day 1 post-lesion and were reduced by 50% after the acute administration of dipyridyl (a liposoluble iron chelator) and aminoguanidine (an inhibitor of the inducible nitric oxide synthase), respectively. Loss of histologically intact tissue and synaptophysin expression as an indicator of synaptogenesis were examined at day 35 post-lesion. Both types of lesion resulted in synaptophysin upregulation in contralateral and ipsilateral cortical areas. On the contrary, brain tissue loss was greater after the striatal (-17%) than the cortical lesion (-5%). Synaptophysin expression and tissue loss were not different between drug- and vehicle-treated rats. Moreover, a set of standard neurological tests revealed a difference in deficit between the both types of lesion, yet only in the acute post-lesion stage. However, it did not distinguish between vehicle- and drug-treated rats whatever the lesion location. Our results indicate that late histological endpoints measurements are not recommended to probe the potential neuroprotective properties of a drug administered within the acute post-lesion stage. They also suggest that inhibition of cytotoxic mechanisms involved in lesion growth is of no clinical interest when it cannot lead to a long-term histological protection and/or increased synaptogenesis.

Flavonoid-inducible modifications to rhamnan O antigens are necessary for Rhizobium sp. strain NGR234-legume symbioses

Rhizobium sp. strain NGR234 produces a flavonoid-inducible rhamnose-rich lipopolysaccharide (LPS) that is important for the nodulation of legumes. Many of the genes encoding the rhamnan part of the molecule lie between 87 degrees and 110 degrees of pNGR234a, the symbiotic plasmid of NGR234. Computational methods suggest that 5 of the 12 open reading frames (ORFs) within this arc are involved in synthesis (and subsequent polymerization) of L-rhamnose. Two others probably play roles in the transport of carbohydrates. To evaluate the function of these ORFs, we mutated a number of them and tested the ability of the mutants to nodulate a variety of legumes. At the same time, changes in the production of surface polysaccharides (particularly the rhamnan O antigen) were examined. Deletion of rmlB to wbgA and mutation in fixF abolished rhamnan synthesis. Mutation of y4gM (a member of the ATP-binding cassette transporter family) did not abolish production of the rhamnose-rich LPS but, unexpectedly, the mutant displayed a symbiotic phenotype very similar to that of strains unable to produce the rhamnan O antigen (NGRDeltarmlB-wbgA and NGROmegafixF). At least two flavonoid-inducible regulatory pathways are involved in synthesis of the rhamnan O antigen. Mutation of either pathway reduces rhamnan production. Coordination of rhamnan synthesis with rhizobial release from infection threads is thus part of the symbiotic interaction.

Early enterocytic differentiation of HT-29 cells: biochemical changes and strength increases of adherens junctions

We have characterized the modulation of cell-cell adhesion and the structure of adherens junctions in the human colon adenocarcinoma HT-29 cell line that differentiates into enterocytes after glucose substitution for galactose in the medium. We demonstrate that differentiated cells (HT-29 Gal) rapidly established E-cadherin-mediated interactions in aggregation assays. This effect is not due to an increase in E-cadherin expression during this early stage of cell differentiation, but rather results from the maturation of preexisting adherens junctions. These junctions are characterized by the redistribution of E-cadherin to the basolateral membrane and its co-localization with the actin cytoskeleton. Subcellular fractionation studies indicate that actin-associated E-cadherins bind beta-catenin and p120ctn. Furthermore, the p120ctn/E-cadherin association is upregulated. These data reveal a cooperative interaction between p120ctn and E-cadherin that corresponds to mature functional adherens junctions able to initiate tight cell-cell adhesion required for epithelium architecture and further affirm the gatekeeper role of p120ctn.

Cytoprotective Efficacy and Mechanisms of the Liposoluble Iron Chelator 2,2′-Dipyridyl in the Rat Photothrombotic Ischemic Stroke Model

We examined the efficacy of the liposoluble iron chelator 2,2'-dipyridyl (DP) in reducing histological damage in rats submitted to cerebral ischemia and the mechanisms involved in the potential cytoprotection. For this purpose, DP (20 mg/kg, i.p.) was administered 15 min before and 1 h after induction of cortical photothrombotic vascular occlusion in rat. Histological studies were performed to assess infarct volume (at days 1 and 3 postischemia) and astromicroglial activation (at day 3 postischemia). Damage to endothelial and neuronal cells was evaluated at day 1 postischemia by quantitative measurements of Evans Blue extravasation and N-acetylaspartate levels, respectively. Cerebral blood flow was recorded in the ischemic core by laser-Doppler flowmetry within the 15 min to 2 h period after photothrombosis. At 4-h postischemia, radical oxygen species (ROS) production was evaluated by measuring brain glutathione concentrations. The cortical expression of the proteins heme oxygenase-1 (HO-1) and hypoxia-inducible factor-1alpha (HIF-1alpha) was analyzed by Western blotting at day 1 postischemia. Infarct volume and ischemic damage to endothelial and neuronal cells were significantly reduced by DP treatment. This cytoprotection was associated with a reduction in ROS production, perfusion deficits, and astrocytic activation. DP treatment also resulted in significant changes in HO-1 (+100%) and HIF-1alpha (-50%) protein expression at the level of the ischemic core. These results report the efficacy of the liposoluble iron chelator DP in reducing histological damage induced by permanent focal ischemia.

Differential MnSOD and HO-1 expression in cerebral endothelial cells in response to sublethal oxidative stress

The two inducible enzymes, manganese superoxide dismutase (MnSOD) and heme-oxygenase-1 (HO-1) may participate in the cellular defense of brain endothelium against oxidative stress. The time-dependent expression of MnSOD and HO-1 mRNAs and proteins was investigated in vitro in rat cerebral endothelial cells (CEC) subjected to sublethal mild or moderate hydroxyl radical-induced oxidative stress. Mild oxidative stress induced increases in both MnSOD and HO-1 mRNA and protein expression. Moderate oxidative stress resulted in a significant reduction in HO-1 mRNA and protein expression, whereas MnSOD expression pattern was similar to that observed after mild oxidative stress. A profound protein loss of both MnSOD and HO-1 was detected 24 h after exposure of CEC to a moderate oxidative stress. The data indicate that cerebral endothelial cells respond by increasing the expression of antioxidant defense enzymes in a manner dependent on the oxidative stress intensity.

Effect of diets with different magnesium content in ischemic stroke rats

Rats fed with low (0.015%), normal (0.08%) or high (0.32%) magnesium (Mg) diet for 5-6 weeks were subjected to photothrombosis-induced infarction. As compared to normal diet, Mg deprivation increased by 45% infarct volume at 24 h after photothrombosis but did not modify the lesion at 4 h after photothrombosis. Mg supplementation did not protect from infarction whatever the time point examined. No differences in pre-ischemic systolic blood pressure and glycemia as well as in post-ischemic kaliemia, calcemia and plasma antioxidant activity were observed between groups. However, plasma total Mg level correlated with plasma antioxidant activity at 4 h after photothrombosis. These results demonstrate that brains from Mg deficient rats are more susceptible to permanent focal ischemia than rats fed with normal or high Mg diet.

Single-breath transfer factor in young healthy adults: 21% or 17.5% inspired oxygen?

For the measurement of the single-breath transfer factor of the lung for carbon monoxide (TL,CO,sb), the American Thoracic Society (ATS) recommends using a test gas with a 21% inspired fraction of oxygen (FI,O2) whereas the European Respiratory Society (ERS) expressly recommends 17-18% FI,O2. The ERS committee argues that with a higher concentration (e.g. 21%) the alveolar fraction of oxygen (and accordingly TL,CO,sb) "varies with the volume of the test gas which is inspired", that is, presumably, in proportion to the volume of the test gas that is diluted in the alveolar volume. The current study measured TL,CO,sb and the transfer coefficient (KCO,sb) in duplicate in 67 healthy adults (age 17-23 yrs) using, in random order, an inspired gas containing either 17.5% or 21% oxygen. A correction was applied for carboxyhaemoglobin, in line with ATS recommendations. As expected, TL,CO,sb was higher with 17.5% FI,O2 test gas compared with 21% FI,O2 test gas (11.98 +/- 2.68 versus 11.38 +/- 2.56 mmol x min(-1) x kPa(-1), respectively) as well as KCO,sb (1.98 +/- 0.24 versus 1.90 +/- 0.23 mmol x min(-1) x kPa(-1), respectively). The ratio of TL,CO,sb measurements was strictly independent of the residual volume/total lung capacity ratio measured with plethysmography. Hence, the rationale used by the European Respiratory Society, which utilises a 17-18% inspired fraction of oxygen test gas for single-breath transfer of the lung for carbon monoxide measurements, would appear to be unwarranted in young healthy adults.

Effects of iNOS-related NO on hearts exposed to liposoluble iron

Inducible nitric oxide synthase (iNOS) protects heart against ischemia/reperfusion injury. However, it is unknown whether the beneficial effects of iNOS are mediated by the interaction of NO with radical oxygen species (ROS). To address this issue, we examined the effects of liposoluble iron-induced ROS generation in isolated perfused hearts from rats treated with lipopolysaccharide (LPS). LPS administration (10 mg/kg, i.p., 6 h before heart removal) induced iNOS expression and increased NO production as indicated by a 3-fold elevation of nitrite level in coronary effluents relative to control hearts. An enhanced expression of hemeoxygenase 1 protein was also observed in septic hearts compared to control. Iron-induced perfusion and contractile deficits were ameliorated by LPS with more important coronary than myocardial benefits. In iron-loaded hearts, oxidative stress as measured by the 2,3 dihydroxybenzoic acid/salicylic acid concentration ratio in cardiac tissue was 23% lower in septic than in control heart although the difference did not reach significance. In addition, the presence of the NO synthase inhibitor N-nitro-L-arginine in the perfusion medium totally blocked NO production but did not reverse the protective effects of LPS. The results indicate that LPS protects from iron-induced cardiac dysfunction by mechanisms independent on ex vivo NO production and suggest that NO acts as a trigger rather than a direct mediator of the cardioprotective effects of LPS in heart exposed to iron.

Effects of a direct injection of liposoluble iron into rat striatum. Importance of the rate of iron delivery to cells

For a better understanding of the role of iron imbalance in neuropathology, a liposoluble iron complex (ferric hydroxyquinoline, FHQ) was injected into striatum of rats. The effects of two modalities of iron injections on brain damage, hydroxyl radical (*OH) production (assessed by the salicylate method coupled to microdialysis) and tissue reactive iron level (evaluated ex vivo by the propensity of the injected structure for lipid peroxidation) were examined. Rapid injection of FHQ (10 nmoles of 5 mM FHQ pH 3 solution over 1-min period) but not that of corresponding vehicle led to extensive damage associated with increased tissue free iron level in the injected region. Conversely, neither lesion nor free iron accumulation was observed after slow FHQ injection (10 nmoles of a 100 microM FHQ pH 7 solution over 1-h period) as compared to corresponding vehicle injection. Production of *OH was induced by slow FHQ injection but not by rapid FHQ injection, probably as a result of in vivo abolition of iron-induced *OH formation by acid pH. Indeed, rapid injection of FAC pH 7 (ferric ammonium citrate, 5 mM in saline) was associated with *OH formation whereas rapid injection of FAC pH 3 did not. Our results identify the rate of iron delivery to cells as an important determinant of iron toxicity and do not support a major role for extracellular *OH in damage associated with intracerebral iron injection.

Chemical preconditioning with 3-nitropropionic acid: lack of induction of neuronal tolerance in gerbil hippocampus subjected to transient forebrain ischemia

Chemical preconditioning using the mitochondrial toxin, 3-nitropropionic acid (3-NP) has been reported to induce neuroprotection against subsequent global ischemia. To investigate the underlying mechanisms, Mongolian gerbils were pretreated with either vehicle or 3-NP at the dose of 3 or 10 mg/kg, intraperitoneal, 3 days prior to a 5-min bilateral carotid artery occlusion followed by either 48 h or 7 days of blood recirculation. Neuronal damage was assessed by a cresyl violet/fuchsin acid staining. Induction of heat shock protein 72 (HSP72) and manganese superoxide dismutase (MnSOD) expression was evaluated by Western blotting. Astroglial and microglial activation was detected by immunohistochemistry (glial fibrillary acid protein) and by histochemistry (isolectin B4 staining), respectively. Present data show that the hippocampal neuronal damage induced by ischemia were of similar extent between the vehicle- and 3-NP-treated gerbils, whatever the dose tested, indicating that 3-NP did not induce tolerance to transient forebrain ischemia under our experimental conditions. The lack of difference in the post-ischemic level of HSP72 and MnSOD protein expression and in the intensity of astroglial and microglial activation represents further indirect indications of the absence of 3-NP preconditioning effect. In conclusion, although chemical preconditioning with 3-NP is a well-established phenomenon at least in vitro and in models of focal ischemia, the relevance of 3-NP as a preconditioning molecule towards global brain ischemia remains an open question.

Rhizobium type III secretion systems: legume charmers or alarmers?

Mutagenesis and sequence analyses of rhizobial genomes have revealed the presence of genes encoding type III secretion systems. Considered as a machine used by plant and animal pathogens to deliver virulence factors into their hosts, this secretion apparatus has recently been proven to play a role in symbiotic bacteria-leguminous plant interactions.