Time-Dependent Mechanical Properties in Polyetherimide 3D-Printed Parts Are Dictated by Isotropic Performance Being Accurately Predicted by the Generalized Time Hardening Model.

The Fused-Deposition Modelling (FDM) technique has transformed the manufacturing discipline by simplifying operational processes and costs associated with conventional technologies, with polymeric materials being indispensable for the development of this technology. A lack of quantification of viscoelastic/plastic behavior has been noted when addressing FDM parts with Polyetherimide (PEI), which is currently being investigated as a potential material to produce functional end-products for the aerospace and health industry. Primary and secondary creep along with stress relaxation tests have been conducted on FDM PEI specimens by applying stresses from 10 to 40 MPa for 100 to 1000 min. Specimens were 3D printed by varying the part build orientation, namely XY, YZ, and XZ. Creep results were fitted to the Generalized Time Hardening equation (GTH), and then this model was used to predict stress relaxation behavior. FDM PEI parts presented an isotropic creep and stress relaxation performance. The GTH model was proven to have a significant capacity to fit viscoelastic/plastic performances for each single build orientation (r > 0.907, p < 0.001), as well as a tight prediction of the stress relaxation behavior (r > 0.998, p < 0.001). Averaged-orientation coefficients for GTH were also closely correlated with experimental creep data (r > 0.958, p < 0.001) and relaxation results data (r > 0.999, p < 0.001). FDM PEI parts showed an isotropic time-dependent behavior, which contrasts with previous publications arguing the significant effect of part build orientation on the mechanical properties of FDM parts. These findings are strengthened by the high correlation obtained between the experimental data and the averaged-coefficient GTH model, which has been proven to be a reliable tool to predict time-dependent performance in FDM parts.

Multidisciplinary team meeting for complex bone and joint infections diagnosis: The PHICTOS study.

BACKGROUND: In France, the most severe bone and joint infections (BJI), called "complex" (CBJI), are assessed in a multidisciplinary team meeting (MTM) in a reference center. However, the definition of CBJI, drawn up by the Health Ministry, is not consensual between physicians. The objective was to estimate the agreement for CBJI classification. METHODS: Initially, five experts from one MTM classified twice, one-month apart, 24 cases as non-BJI, simple BJI or CBJI, using the complete medical record. Secondly, six MTMs classified the same cases using standardized information. Agreements were estimated using Fleiss and Cohen kappa (κ) coefficients. RESULTS: Inter-expert agreement during one MTM was moderate (κ=0.49), and fair (κ=0.23) when the four non-BJIs were excluded. Intra-expert agreement was moderate (κ=0.50, range 0.27-0.90), not improved with experience. The overall inter-MTM agreement was moderate (κ=0.58), it was better between MTMs with professor (κ=0.65) than without (κ=0.51) and with longer median time per case (κ=0.60) than shorter (κ=0.47). When the four non-BJIs were excluded, the overall agreement decreased (κ=0.40). CONCLUSION: The first step confirmed the heterogeneity of CBJI classification between experts. The seemingly better inter-MTM than inter-expert agreement could be an argument in favour of MTMs, which are moreover a privileged place to enhance expertise. Further studies are needed to assess these results as well as the quality of care and medico-economic outcomes after a MTM.

Key features of bone and joint infections following the implementation of reference centers in France.

OBJECTIVES: French reference centers for bone and joint infections (BJI) were implemented from 2009 onwards to improve the management of complex BJIs. This study compared BJI burden before and after the implementation of these reference centers. PATIENTS AND METHODS: BJI hospital stays were selected from the 2008 and 2013 national hospital discharge database using a validated algorithm, adding the new complex BJI code created in 2011. Epidemiology and economic burden were assessed. RESULTS: BJI prevalence increased in 2013 (70 vs. 54/100,000 in 2008). Characteristics of BJI remained similar between 2008 and 2013: septic arthritis (50%), increasing prevalence with age and sex, case fatality 5%, mean length of stay 17.5 days, rehospitalization 20%. However, device-associated BJIs increased (34 vs. 26%) as well as costs (€421 million vs. €259 in 2008). Similar device-associated BJI characteristics between 2008 and 2013 were: septic arthritis (70%), case fatality (3%), but with more hospitalizations in reference centers (34 vs. 30%) and a higher cost per stay. Among the 7% of coded complex BJIs, the mean length of stay was 22.2 days and mean cost was €11,960. CONCLUSIONS: BJI prevalence highly increased in France. Complex BJI prevalence assessment is complicated by the absence of clinical consensus and probable undercoding. A validation of clinical case definition of complex BJI is required.

Use of telemedicine in the management of infectious diseases.

Communication technologies have invaded our daily lives. Several studies have assessed these technologies in the management of infectious diseases (mainly HIV). Weekly short text messages and real-time compliance monitoring assessed in HIV patients are both associated with higher compliance in low-income countries. Virtual consultations to monitor stable chronic HIV patients or tuberculosis treatment in high-income countries appear to be acceptable and efficient. Although assessed in small studies, virtual monitoring seems to reinforce the doctor-patient relationship and the relation between primary care settings and hospitals in various infectious diseases (endocarditis, urinary tract infection, skin and soft tissue infection, HIV, tuberculosis, hepatitis C). A better prevention of infectious diseases (mainly sexually transmitted infections) seems to be observed with telemedicine tools. As fees for teleconsultation or telemonitoring have yet to be defined, the development and evaluation (cost effectiveness) of these tools are difficult. The regulatory framework will need to be improved to encourage such developments, all the while ensuring the confidentiality of data. The development of new tools will require the collaboration of physicians, users, and healthcare systems.

Diagnostic delay of pyogenic vertebral osteomyelitis and its associated factors.

OBJECTIVES: Pyogenic vertebral osteomyelitis (PVO) is a rare disease with possible severe complications (e.g. sepsis and spinal cord injury). In the 1990s, diagnostic delay (DD) was often extensive as PVO has a non-specific clinical spectrum, mostly afebrile with back pain, and access to magnetic resonance imaging (MRI) was not straightforward. Our aim was to perform a new study focusing on the clinical spectrum and DD of PVO and its associated factors. METHOD: This study examined a prospective cohort of 88 patients having PVO with microbiological identification between 15 November 2006 and 15 November 2010. RESULTS: The 88 patients included in the study (female:male ratio 1:8) had a mean age of 64.1 years. The mean (sd) DD was 45.5 (50.4) days (range 2-280), and 46 patients (52.2%) were febrile at diagnosis. The main microorganism involved was Staphylococcus (n = 45; 51.1%). In univariate and multivariate analyses, age > 75 years, antecedent back pain, involvement of bacteria, topography of PVO, and anti-inflammatory drug intake did not affect the DD, unlike a C-reactive protein (CRP) value > 63 mg/L or a positive blood culture (DD lowered from 73 to 17 days and from 90 to 30 days, respectively). Conversely, X-ray investigation was associated with a longer DD (from 14 to 34.7 days). Severity at diagnosis was not significantly different depending on the intake of anti-inflammatory drugs. CONCLUSIONS: Despite easier access to MRI, the DD for PVO remains long. One shortening factor is a high CRP value, which could be a useful diagnostic tool in case of back pain. Anti-inflammatory drugs seem to have no impact on DD and severity at diagnosis.

Rapid HIV test in family practice.

BACKGROUND: The 2010-2014 HIV/AIDS French program recommends using HIV rapid diagnostic tests in family practice. Our aim was to assess the acceptability and feasibility of the RDT in family practice in France. METHODS: The first part of this study was to determine the opinions of family practitioners (FPs) concerning the news guidelines for screening and the possible use of rapid HIV tests in their practice. The second part was a feasibility study of the actual use of rapid HIV tests given to FPs during six months. The third part was a qualitative analysis of experience feedback to determine the impediments to using rapid HIV tests. RESULTS: Seventy-seven percent of the 352 FPs interviewed were favorable to rapid HIV tests use. The three main impediments were: misinterpretation of test result, complexity of quality control, and lack of training: 23 of the 112 FPs having volunteered to evaluate the rapid HIV tests followed the required training session. Sixty-nine tests were handed out, and three rapid HIV tests were used; the qualitative study involved 12 FPs. The participants all agreed on the difficult use of rapid HIV tests in daily practice. The main reasons were: too few opportunities or requests for use, complex handling, difficulties in proposing the test, fear of having to announce seropositivity, significantly longer consultation. CONCLUSION: Although FPs are generally favorable to rapid HIV tests use in daily practice, the feasibility and contribution of rapid HIV tests are limited in family practice.

Hospital and ambulatory management, and compliance to treatment in HIV infection: regional health insurance agency analysis.

OBJECTIVE: We had for objective to study HIV management (hospital, ambulatory, and mixed) and assess compliance with health insurance database. METHOD: We conducted a retrospective study using the French Social Security (CPAM) database. The inclusion criteria were: age>18years of age, at least 2 prescriptions of antiretroviral therapy. RESULTS: Five hundred and seventy-five patients were included: extra-hospital (12), hospital (162), mixed (401). The prescriptions were exclusively hospital issued for 76.2% of the patients. Among the mixed group patients, 91% of treatments were delivered at least once in the community, and 45.6% of biological tests were performed in private laboratories at least once. The sex ratio (2.1 vs. 1.3), the number of patients having switched antiretroviral therapy (36.7% vs. 27.8%), and the frequency of biological tests (3.1 vs. 2.6) were significantly higher in the mixed group compared to the hospital group. The mean compliance was 90% in the hospital group and 91.8% in the mixed group. The compliance was<80% for 104 patients (21.8%). Patients with≥80% compliance were older (46.1years of age vs. 42.7years of age), with more frequent biological tests (3 per year vs. 2.5 per year), and more frequent switches in treatment (35.4% vs. 26.0%). CONCLUSION: Prescriptions of ARV were almost exclusively hospital issued. Their dispensation and biological tests were split between hospital and extra-hospital settings. Most patients demonstrated an optimal compliance. The CPAM database allows describing HIV management and assessing compliance.

Microbiological diagnosis of vertebral osteomyelitis: relevance of second percutaneous biopsy following initial negative biopsy and limited yield of post-biopsy blood cultures.

The purpose of this investigation was to evaluate the microbiological diagnosis yield of post-biopsy blood cultures (PBBCs) and second percutaneous needle biopsy (PNB) following an initial negative biopsy in vertebral osteomyelitis (VO) without bacteremia. A retrospective multicenter study was performed. Patients with VO, pre-biopsy negative blood culture(s), ≥1 PNB, and ≥1 PBBC (0-4 h) were included. One hundred and sixty-nine PNBs (136 first and 33 following initial negative biopsy) were performed for 136 patients (median age = 58 years, sex ratio M/F = 1.9). First and second PNBs had a similar yield: 43.4 % (59/136) versus 39.4 % (13/33), respectively. Only two PBBCs (1.1 %) led to a microbiological diagnosis. The strategy with positive first PNB and second PNB following an initial negative result led to microbiological diagnosis in 79.6 % (74/93) of cases versus 44.1 % (60/136) for the strategy with only one biopsy. In the multivariate analysis, young age (odds ratio, OR [95 % confidence interval (CI)] = 0.98 [0.97; 0.99] per 1 year increase, p = 0.02) and >1 sample (OR = 2.4 ([1.3; 4.4], p = 0.007)) were independently associated with positive PNB. To optimize microbiological diagnosis in vertebral osteomyelitis, performing a second PNB (after an initial negative biopsy) could lead to a microbiological diagnosis in nearly 80 % of patients. PBBC appears to be limited in microbiological diagnosis.

p21(WAF1) gene promoter is epigenetically silenced by CTIP2 and SUV39H1.

Mainly regulated at the transcriptional level, the cellular cyclin-dependent kinase inhibitor, CDKN1A/p21(WAF1) (p21), is a major cell cycle regulator of the response to DNA damage, senescence and tumor suppression. Here, we report that COUP-TF-interacting protein 2 (CTIP2), recruited to the p21 gene promoter, silenced p21 gene transcription through interactions with histone deacetylases and methyltransferases. Importantly, treatment with the specific SUV39H1 inhibitor, chaetocin, repressed histone H3 lysine 9 trimethylation at the p21 gene promoter, stimulated p21 gene expression and induced cell cycle arrest. In addition, CTIP2 and SUV39H1 were recruited to the silenced p21 gene promoter to cooperatively inhibit p21 gene transcription. Induction of p21(WAF1) gene upon human immunodeficiency virus 1 (HIV-1) infection benefits viral expression in macrophages. Here, we report that CTIP2 further abolishes Vpr-mediated stimulation of p21, thereby indirectly contributing to HIV-1 latency. Altogether, our results suggest that CTIP2 is a constitutive p21 gene suppressor that cooperates with SUV39H1 and histone methylation to silence the p21 gene transcription.

Neurotrophins modulate monocyte chemotaxis without affecting macrophage function.

Neurotrophins nerve growth factor (NGF), brain-derived growth factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) and their high-affinity tyrosine protein kinase receptor (Trk) family, TrkA, TrkB, TrkC, and low-affinity p75(NTR) receptor, are key molecules implicated in the development of the central nervous system. Increasing evidence suggests that they also have physiological and pathological roles outside the nervous system. In this study we examined the expression of neurotrophins and their receptors in human activated macrophages and to what extent neurotrophins themselves modulate macrophage activation, in a model of primary adult monocyte-derived macrophage. Our data indicate that macrophages express neurotrophin and neurotrophin receptor genes differentially, and respond to cell stimulation by specific inductions. Neurotrophins did not modify the antigen-presenting capacities of macrophages or their production of proinflammatory cytokines, but somehow skewed their activation phenotype. In contrast, NGF clearly increased CXCR-4 expression in macrophage and their chemotactic response to low CXCL-12 concentration. The differential effect of specific macrophage stimuli on neurotrophin expression, in particular NGF and NT-3, and the specific enhancement of CXCR-4 expression suggest that neurotrophins might participate in tissue-healing mechanisms that should be investigated further in vivo.

[Acute renal failure with acyclovir in a 42-year-old patient without previous renal dysfunction]. / Insuffisance rénale aiguë sous aciclovir chez un patient de 42 ans sans atteinte rénale préalable.

INTRODUCTION: Herpetic meningoencephalitis is treated with acyclovir (15 mg/kg/8 h). This higher dosage enhance the risk of acute renal failure. CASE REPORT: We report the case of a previously healthy 42 years old man treated by intravenous aciclovir 1g/8 h for a herpetic meningoencephalitis. He presented an acute renal failure and an acute confusional state at the end of the treatment. Renal function and neurologic status improved rapidly with increased hydration and stop of the antiviral therapy. CONCLUSION: If acyclovir is usually well tolerated, there is also a risk of acute nephropathy, especially dose-dependent. We point out the need to monitor renal function when high dosage of acyclovir is indicated.

Macrophage activation switching: an asset for the resolution of inflammation.

Macrophages play a central role in inflammation and host defence against microorganisms, but they also participate actively in the resolution of inflammation after alternative activation. However, it is not known whether the resolution of inflammation requires alternative activation of new resting monocytes/macrophages or if proinflammatory activated macrophages have the capacity to switch their activation towards anti-inflammation. In order to answer this question, we first characterized differential human macrophage activation phenotypes. We found that CD163 and CD206 exhibited mutually exclusive induction patterns after stimulation by a panel of anti-inflammatory molecules, whereas CCL18 showed a third, overlapping, pattern. Hence, alternative activation is not a single process, but provides a variety of different cell populations. The capacity of macrophages to switch from one activation state to another was then assessed by determining the reversibility of CD163 and CD206 expression and of CCL18 and CCL3 production. We found that every activation state was rapidly and fully reversible, suggesting that a given cell may participate sequentially in both the induction and the resolution of inflammation. These findings may provide new insight into the inflammatory process as well as new fields of investigation for immunotherapy in the fields of chronic inflammatory diseases and cancer.

[Legionella pneumonia in an immunocompetent child]. / La légionellose chez l'enfant immunocompétent: a propos d'un cas.

We report a case of Legionella pneumonia in an immunocompetent child. Legionella pneumonia is a rare pathology among children, and even rarer when they are immuno-competent; a few cases have been reported in the literature. This is explained by the fact that infection occurs primarily to immuno-suppressed patients. Legionella bacteria are not systematically sought for in front of child's atypical pneumonia, contrary to Mycoplasma or Chlamydiae. In addition, a number of cases are probably not even noticed because either not serious (Pontiac fever), spontaneously cured, or cured with macrolides prescribed in the case of suspected pneumonia with Mycoplasma.

Evaluation of CD4+ T cells proliferating to grass pollen in seasonal allergic subjects by flow cytometry.

Our objective was to characterize T-cell responses to Phleum pratense in grass pollen allergic individuals and healthy controls using the fluorescent dye PKH26. Peripheral blood mononuclear cells were stimulated with P. pratense, or with recall antigens, and CD3+/CD4+ and CD3+/CD8+ T-cells that had proliferated were analysed by flow cytometry. In the presence of P. pratense CD4+/CD3+ T-cells proliferated more in grass pollen sensitive atopic patients than in nonallergic controls or in nongrass pollen sensitive atopic subjects. PPD and TT recall antigens elicited uniformly high proliferation in all T-cell subsets. Only half of pollen sensitive patients also had an increased proliferation of CD3+/CD8+ T-cells in response to P. pratense. We determined precursor frequency of CD4+ T cells in the original population that responded to P. pratense and found values ranging from 1 x 10-3 to 0.6 x 10-1, in the same range as those measured for PPD and TT. In conclusion, grass pollen sensitive atopic patients show enhanced CD4+ T-cell reactivity to P. pratense, and this could be related to the presence of elevated numbers of circulating allergen-specific CD4+ T cells. This flow cytometric method should allow the identification of other phenotypic markers such as intracellular cytokines in allergen specific responding CD4+ T cells.

Expression of excitatory amino acid transporter-2 (EAAT-2) and glutamine synthetase (GS) in brain macrophages and microglia of SIVmac251-infected macaques.

Na+-dependent transporters for glutamate (excitatory amino acid transporters, EAATs) clear extracellular glutamate in the brain and prevent excitotoxic neuronal damage. Glutamine synthetase (GS) provides metabolic support for neurones by producing the neurotrophic amino acid glutamine. EAAT and GS expression has recently been demonstrated in macrophages and microglial cells in vitro, and in two models of acute inflammation in vivo. This observation might modify our current understanding of brain inflammation, which considers activated microglia and brain macrophages as the main neurotoxic cells through their production of a variety of neurotoxins, including glutamate. EAAT and GS expression by these cells would entail neuroprotective and neurotrophic properties, counterbalancing the deleterious consequences of microglial activation. Macaque infection by the simian immunodeficiency virus (SIV) is considered the most relevant model for human acquired immunodeficiency syndrome (AIDS), including chronic inflammation of the brain at the early asymptomatic stage of the infection, followed by an AIDS-like disease where neuronal death occurs. We studied the expression of EAAT-2 and GS in the brains of three SIVmac251-infected and two noninfected cynomolgus macaques. We found that both microglia and brain macrophages expressed EAAT-2 and GS in infected primates, suggesting that these cells might, like astrocytes, clear extracellular glutamate and provide glutamine to neurones. Microglia and macrophages could thus have neuroprotective and neurotrophic properties in addition to their production of neurotoxins. This finding might explain the contrast between early intense microglial activation and the late occurrence of neuronal apoptotic cell death, which is mainly observed at the terminal stage of the disease.

Role of glutamate transporters in the regulation of glutathione levels in human macrophages.

Cysteine is the limiting precursor for glutathione synthesis. Because of its low bioavailability, cysteine is generally produced from cystine, which may be taken up through two different transporters. The cystine/glutamate antiporter (x system) transports extracellular cystine in exchange for intracellular glutamate. The X(AG) transport system takes up extracellular cystine, glutamate, and aspartate. Both are sensitive to competition between cystine and glutamate, and excess extracellular glutamate thus inhibits glutathione synthesis, a nonexcitotoxic mechanism for glutamate toxicity. We demonstrated previously that human macrophages express the glutamate transporters excitatory amino acid transporter (EAAT)1 and EAAT2 (which do not transport cystine, X system) and overcome competition for the use of cystine transporters. We now show that macrophages take up cystine through the x and not the X(AG) system. We also found that glutamate, although competing with cystine uptake, dose-dependently increases glutathione synthesis. We used inhibitors to demonstrate that this increase is mediated by EAATs. EAAT expression in macrophages thus leads to glutamate-dependent enhancement of glutathione synthesis by providing intracellular glutamate for direct insertion in glutathione and also for fueling the intracellular pool of glutamate and trans-stimulating the cystine/glutamate antiporter.

Na+-dependent high-affinity glutamate transport in macrophages.

Excessive accumulation of glutamate in the CNS leads to excitotoxic neuronal damage. However, glutamate clearance is essentially mediated by astrocytes through Na+-dependent high-affinity glutamate transporters (excitatory amino acid transporters (EAATs)). Nevertheless, EAAT function was recently shown to be developmentally restricted in astrocytes and undetectable in mature astrocytes. This suggests a need for other cell types for clearing glutamate in the brain. As blood monocytes infiltrate the CNS in traumatic or inflammatory conditions, we addressed the question of whether macrophages expressed EAATs and were involved in glutamate clearance. We found that macrophages derived from human blood monocytes express both the cystine/glutamate antiporter and EAATs. Kinetic parameters were similar to those determined for neonatal astrocytes and embryonic neurons. Freshly sorted tissue macrophages did not possess EAATs, whereas cultured human spleen macrophages and cultured neonatal murine microglia did. Moreover, blood monocytes did not transport glutamate, but their stimulation with TNF-alpha led to functional transport. This suggests that the acquisition of these transporters by macrophages could be under the control of inflammatory molecules. Also, monocyte-derived macrophages overcame glutamate toxicity in neuron cultures by clearing this molecule. This suggests that brain-infiltrated macrophages and resident microglia may acquire EAATs and, along with astrocytes, regulate extracellular glutamate concentration. Moreover, we showed that EAATs are involved in the regulation of glutathione synthesis by providing intracellular glutamate. These observations thus offer new insight into the role of macrophages in excitotoxicity and in their response to oxidative stress.

Quantitative study of beta1-integrin expression and fibronectin interaction profile of T lymphocytes in vitro infected with HIV.

Cell-extracellular matrix interactions, regulated in part by beta1-integrins, play a key role in the recirculation of T lymphocytes and tissue infiltration in inflammatory and immune responses. HIV infection may affect CD4+ T cell adhesion, and the trafficking and migration of these cells, which are crucial for foreign antigen recognition. We investigated this by studying the expression of the beta1-integrin chains CD29 and CD49c, -d, -e, and -f, on in vitro HIV-infected primary T cells. We also assessed fibronectin binding and production by CD4+ lymphocytes. X4 (HIV-1/LAI), R5 (HIV-1/Ba-L), and X4R5 (HIV-2/ROD) strains, and X4R5 primary isolates (HIV-1/DAS, HIV-1/THI), with different cytopathogenicity and replication kinetics, were used. Beta1-integrin expression on CD4+ and CD4- T cell subpopulations was regulated by cell activation with phytohemagglutinin-P and interleukin 2, but was unaffected by HIV infection, even at the peak of viral replication and CD4+ cell depletion. Similarly, fibronectin binding to CD4+ lymphocytes was not affected by HIV infection. This suggests that infected lymphocytes may be able to extravasate, migrate, and recirculate within the body until their death.