Compressibility and Structural Transformations of Aluminogermanate Imogolite Nanotubes under Hydrostatic Pressure.

We present in situ pressure experiments on aluminogermanate nanotubes studied by X-ray scattering and absorption spectroscopy measurements. Structural transformations under hydrostatic pressure below 10 GPa are investigated as a function of the morphology, organization, or functionalization of the nanotubes. Radial deformations, ovalization for isolated nanotubes, and hexagonalization when they are bundled are evidenced. Radial collapse of single-walled nanotubes is shown to occur, in contrast to the double-walled nanotubes. The effect of the transmitting pressure medium used on the collapse onset pressure value is demonstrated. Axial Young's moduli are determined for isolated (400 GPa) and bundled (600 GPa) single-walled nanotubes, double-walled nanotubes (440 GPa), and methylated single-walled nanotubes (200 GPa).

[Outcomes of respiratory rehabilitation program in lung transplant recipients: a quasi experimental study]. / Resultados de un programa de rehabilitación respiratoria en pacientes receptores de trasplante pulmonar: estudio cuasiexperimental.

INTRODUCTION: Lung transplant (LT) is the ultimate option for end-stage lung diseases. Malnutrition and sarcopenia, common in LT recipients, can be reversible with adequate exercise and nutrition. This study aims to assess changes in physical performance and aerobic capacity after a 10-week rehabilitation program (RP) in LT recipients, as well as to describe the prevalence of sarcopenia and malnutrition before and after RP and their influence on clinically relevant outcomes. MATERIALS AND METHODS: Quasi-experimental study, before and after a 10-week PR in first-time TP recipients, aged over 18 years, from January 2022 to September 2023. Aerobic exercise capacity was assessed through the 6-minute walking test (6MWT) and peak oxygen consumption (VO2peak); and physical performance was measured using the Short Physical Performance Battery (SPPB). Additionally, the prevalence of sarcopenia was described according to the criteria of the European Working Group on Sarcopenia in Older People (EWGSOP2) and malnutrition according to the criteria of the Global Leadership Initiative on Malnutrition (GLIM). RESULTS: Of the 41 patients, 56% had sarcopenia and 80% had malnutrition. After RP, the distance walked in the 6MWT increased by 66.3m (p=0.004) in men and 61m (p=0.001) in women. VO2peak increased in men by a mean of 3.1ml/min/kg (p=0.024). Physical performance improved significantly in both men and women according to the Short Physical Performance Battery (SPPB), with clinically relevant differences of 1.6 pts (p<0.001) and 1.2 pts (p=0.012), respectively. The prevalence of sarcopenia decreased to 24% and malnutrition to 61%. CONCLUSIONS: RP proved to be an effective and safe intervention for LT recipients. In addition to improvements in skeletal muscle strength and exercise capacity, a reduction in the prevalence of sarcopenia and malnutrition was also observed.

[Relationship between frailty and functional status in lung transplant candidates]. / Relación entre la fragilidad y la capacidad funcional en los pacientes candidatos a trasplante de pulmón.

INTRODUCTION: Lung transplant (LT) is one of the therapeutic options for patients with terminal respiratory diseases. It is highly important to incorporate the functional status and frailty assessment into the selection process of candidates for LT. OBJECTIVES: Identify the prevalence of frailty in the LT waiting list. Study the relationship between frailty, functional status, Lung Allocation Score (LAS) and muscular dysfunction. METHODOLOGY: Descriptive transversal study of patients on the waiting list for LT. POPULATION: 74 patients with chronic respiratory diseases assessed by the lung transplant committee and accepted to be transplanted in a university hospital in Barcelona. The outcome variables were frailty status was evaluate for SPPB test, functional capacity was evaluate for the six-minute walking test (6MWT) and muscular dysfunction. The results were analyzed with the statistical package STATA 12. RESULTS: Sample of 48 men and 26 women, with a median age of 56.55 years (SD 10.87. The prevalence of frailty assessed with the SPPB was 33.8% (8.1% are in frailty and 25.7% are in a state of pre-frailty). There is a relationship between the SPPB, 6MWT and maximal inspiratory pressure, but not with others force values. There is a relationship between the risk of frailty (scores below 9 in SPPB) and the meters walked in 6 but not with the LAS. CONCLUSIONS: The risk of frailty in patients with terminal chronic respiratory diseases is high. Frailty is related with functional capacity, but not with LAS.

Altered ligands reveal limited plasticity in the T cell response to a pathogenic epitope.

Experimental leishmaniasis offers a well characterized model of T helper type 1 cell (Th1)-mediated control of infection by an intracellular organism. Susceptible BALB/c mice aberrantly develop Th2 cells in response to infection and are unable to control parasite dissemination. The early CD4(+) T cell response in these mice is oligoclonal and reflects the expansion of Vbeta4/ Valpha8-bearing T cells in response to a single epitope from the parasite Leishmania homologue of mammalian RACK1 (LACK) antigen. Interleukin 4 (IL-4) generated by these cells is believed to direct the subsequent Th2 response. We used T cells from T cell receptor-transgenic mice expressing such a Vbeta4/Valpha8 receptor to characterize altered peptide ligands with similar affinity for I-Ad. Such altered ligands failed to activate IL-4 production from transgenic LACK-specific T cells or following injection into BALB/c mice. Pretreatment of susceptible mice with altered peptide ligands substantially altered the course of subsequent infection. The ability to confer a healer phenotype on otherwise susceptible mice using altered peptides that differed by a single amino acid suggests limited diversity in the endogenous T cell repertoire recognizing this antigen.

Intralesional regulatory T-cell suppressive function during human acute and chronic cutaneous leishmaniasis due to Leishmania guyanensis.

The levels of regulatory T cells (Treg cells), analyzed by Foxp3 mRNA expression, were determined in lesions from patients with acute cutaneous leishmaniasis (ACL) and chronic cutaneous leishmaniasis (CCL). We demonstrated that Treg cells preferentially accumulate in lesions from ACL patients during the early phase of infection (lesion duration of less than 1 month). In addition, levels of Foxp3 mRNA transcripts were significantly higher in specimens from patients with CCL than in those from patients with ACL, suggesting a critical role of intralesional Treg cells in CCL. Intralesional Treg cells from both ACL and CCL patients were shown to have suppressive functions in vitro, since they inhibited the gamma interferon (IFN-gamma) produced by CD4(+) CD25(-) T cells purified from peripheral blood mononuclear cells from the same patient in response to Leishmania guyanensis stimulation. Intralesional 2,3-indoleamine dioxygenase (IDO) mRNA expression was associated with that of Foxp3, suggesting a role for IDO in the suppressive activity of intralesional Treg cells. In addition, a role, albeit minor, of interleukin-10 (IL-10) was also demonstrated, since neutralization of IL-10 produced by intralesional T cells increased IFN-gamma production by effector cells in an in vitro suppressive assay. These results confirm the role of intralesional Treg cells in the immunopathogenesis of human Leishmania infection, particularly in CCL patients.

[Spanish validation of the Autonomic Standards Assessment Form in spinal cord injuries]. / Validación española del cuestionario Autonomic Standards Assessment Form en la lesión medular.

INTRODUCTION AND OBJECTIVES: Autonomic nervous system (ANS) dysfunction in patients with spinal cord injury (SCI) severely impacts morbidity and mortality. However, research initiatives aiming to gain insight into the direct impact of ANS dysfunction on health outcomes in persons with SCI are still lacking. Thus, this study had 2main objectives: 1) to translate into Spanish the revised edition of the International Standards on documentation of remaining Autonomic Function after SCI (ISAFSCI), and 2) to describe the impact of ANS dysfunction in a sample of SCI patients. MATERIAL AND METHODS: Cross-sectional observational pilot study in 51 traumatic SCI patients (> 1 year after injury). Demographic, medical and ISAFSCI data were studied. RESULTS: The Spanish version of the ISAFSCI showed that the most altered systems in the sample were sweating control (above-lesion hyperhidrosis in 33.3%; below-lesion hyperhidrosis in 17.6%; below-lesion hypohidrosis in 21.6%) and temperature control (hyperthermia in 76.5%). In addition, 74.5% of the sample had complete loss of control of the lower urinary tract, and 82.4% had no control of the bowel. Finally, genital arousal was reflex in 47.1% and orgasm and ejaculation were reduced or altered in most of the patients (92.2% and 84.3%, respectively). CONCLUSION: The Spanish version of the ISAFSCI is a useful and practical tool, and can be employed in clinical practice to assess ANS function in patients with SCI. Understanding the role of ANS in persons with SCI is crucial to improve their health status and reduce secondary complications post-SCI, and consequently help to improve the clinical management in these individuals.

Shape-controlled platinum nanocubes and their assembly into two-dimensional and three-dimensional superlattices.

Liquid-liquid phase transfer has been used to synthesize platinum nanocrystals with a cubic morphology. By finely tuning the parameters controlling the nucleation and growth processes, nanometric truncated cubes or perfect cubes may be obtained. To our knowledge, this is the first time such shapes are obtained with this procedure. The importance of both the length of the capping agent to control the growth process and the bromide anions as poison for the (111) facet is shown. The low degree of size polydispersity allows these nanocrystals to self-assemble with a long-range ordering in two-dimensional and three-dimensional supracrystals. According to the nanocrystal shape, simple cubic or face-centered cubic supracrystals are observed. It is remarkable to notice that well-faceted supracrystals with sizes on the order of 10 microm may be obtained.

Regulation of protective immunity against Leishmania major in mice.

Resolution of lesions induced by Leishmania major in mice results from the development of Th1 responses. Cytokines produced by Th1 cells activate macrophages to a parasiticidal state. The development of Th2 responses in mice from a few strains underlies susceptibility to infection. Cytokines produced by Th2 cells exacerbate the development of lesions because of their deactivating properties for macrophages. This murine model of infection has provided significant insight into the mechanisms intrinsic to the differentiation of disparate CD4+ T cell subsets in vivo in animals from different genetic backgrounds.

Substantial improvement of nanotube processability by freeze-drying.

As-produced carbon nanotubes often contain a fraction of impurities such as metal catalysts, inorganic supports, and carbon by-products. These impurities can be partially removed by using acidic dissolution. The resulting nanotube materials have to be dried to form a powder. The processability of nanotubes subjected to regular (thermal vaporisation) drying is particularly difficult because capillary forces pack and stick the nanotubes irreversibly, which limits their dispersability in polymeric matrices or solvents. We show that this dramatic limitation can be circumvented by using freeze-drying instead of regular-drying during nanotube purification process. In this case, the nanotubes are trapped in frozen water which is then sublimated. As a result the final powder is significantly less compact and, more important, the nanotubes can be easily dispersed with no apparent aggregates, thereby greatly enhancing their processability, e.g., they can be used to make homogeneous composites and fibers. Results from coagulation spinning from water-based dispersions of regularly-dried and freeze-dried nanotubes are compared. We also show that freeze-dried materials, in contrast to regularly-dried materials, can be dissolved in organic polar solvents using alkali-doped nanotubes. High resolution TEM and XRD analysis demonstrate that the nanotube structure and quality are not affected at the nanoscale by freeze-drying treatments.

Graphene oxide-carbon nanotube hybrid assemblies: cooperatively strengthened OH···O[double bond, length as m-dash]C hydrogen bonds and the removal of chemisorbed water.

Owing to their great significance for energy storage and sensing applications, multi-layer papers consisting of graphene oxide-carbon nanotube (GO-CNT) hybrid sheets were prepared by in situ exfoliation of graphite oxide in the presence of oxidized CNTs (oCNTs). For the first time we elucidate the influence of oCNTs on chemisorbed water (CW), i.e. the water molecules inherently bound to the oxygen functional groups (OFGs) of graphene oxide (GO) and responsible for irreversible structural damage upon thermal reduction processes. We show that oCNTs self-assemble onto GO sheets during the liquid phase processing steps by forming cooperatively strengthened OH···O[double bond, length as m-dash]C hydrogen bonds between the carboxylic groups of the oCNTs and OFGs of GO. At oCNT amounts of about 10 to 15 wt% this leads to the displacement of considerable amounts of CW without altering the original chemical composition of GO. The thermally reduced GO-CNT (rGO-CNT) papers reveal improved sp2 character and an enhancement of the specific capacitance by 75% with respect to thermally reduced GO (rGO), largely due to the effective removal of CW by oxidized CNTs. These findings disclose the relevance of the cooperative hydrogen bonding phenomena in graphene oxide paper/film electrodes for the development of improved electrochemical energy storage and sensing devices.

Mechanisms of Mycobacterium leprae-specific T-cell deficiency in lepromatous leprosy.

Patients suffering from lepromatous leprosy fail to develop an efficient cell-mediated immunity towards Mycobacterium leprae, the causative agent. The mechanism of such a specific T-cell tolerance to the bacillus remains a key question in the pathophysiology of leprosy. Macrophages do not show any intrinsic defect in phagocytizing and killing M. leprae or in presenting antigen to helper T-cells. On the other hand, M. leprae-reactive helper T-cells do persist in lepromatous patients, but their activation appears to prevented by active suppressor mechanisms, involving both suppressor T-cells and macrophages. The target of this specific suppression could be the interleukin 2-producing T-cell subset. A better molecular definition of M. leprae antigens, both by monoclonal antibodies and T-cell clones, should open new perspectives for further analysis of the regulation of immune responses to M. leprae.

An isoelectric focusing method for the study of the humoral response against the antigen 85 complex of Mycobacterium bovis BCG in the different forms of leprosy.

Isoelectric focusing was used to separate the three components of the antigen 85 complex of Mycobacterium bovis BCG. Antibody responses of leprosy patients against each Mycobacterium bovis BCG. Antibody responses of leprosy patients against each component were quantitated by densitometric analysis of immunoblot assays. The 85A component was recognized by 40% (8/20) of the lepromin positive and negative healthy subjects, by 76% (19/25) of the tuberculoid and by 96% (24/25) of the lepromatous leprosy sera. In contrast, the 85B component was not stained by the control sera, nor by the tuberculoid leprosy sera but by 64% (16/25) of the lepromatous leprosy sera. The results suggest that antigen 85B contains one or several epitopes that are specifically recognized by sera of lepromatous leprosy patients only.

Cytokines in parasitic diseases: the example of cutaneous leishmaniasis.

The essential role of cytokines in parasitic diseases has been emphasised since the in vivo description of the importance of T helper 1 (Th1) and T helper 2 (Th2) CD4+ T cell responses in resistance and susceptibility to infection with L. major in mice. Th1 cells produced IL-2, IFN-gamma and Lymphotoxin T (LT) and Th2 cells produce IL-4, IL-5 and IL-13. In this model of infection the correlation between on the one hand resistance to infection and the development of a Th1 response and on the other hand susceptibility and Th2 cell development allowed the identification of the mechanisms directing the differentiation of CD4+ T cell precursors towards either Th1 type or Th2 type responses. Cytokines are the crucial inducer of functional CD4+ T cell subset differentiation during infection with L. major. IL-12 and IFN-gamma direct the differentiation of Th1 response and IL-4 of a Th2 response. In susceptible mice, careful analysis of IL-4 production during the first days of infection has shown that the IL-4 produced as a result of a very early burst of IL-4 mRNA expression (16 hours) plays a essential role in the maturation of a Th2 CD4+ T cell response by rendering the CD4+ T cell precursors unresponsive to IL-12. Activation of a restricted population of CD4+ T cells expressing the V beta 4 V alpha 8 TCR heterodimer after recognition of a single antigen, the LACK (Leishmania Activated c Kinase) antigen, resulted in this rapid production of IL-4 required for the subsequent CD4+ T cell differentiation. Thus, tolerization of these cells might contribute a strategy for preventing infection with L. major.

Bundles of identical double-walled carbon nanotubes.

In a sample produced by catalytic chemical vapor deposition (CCVD), the structure of the carbon nanotubes (diameter and helicity) which governs their electronic properties, is determined by electron diffraction. We found that most of the smallest bundles are constituted of identical double-walled carbon nanotubes.

Original magnetic alignment of a nematic phase containing single-walled nanotubes.

Dispersions of single-walled carbon nanotubes in a 4-pentyl-4'-cyano-biphenyl nematic liquid crystal matrix are studied by X-ray scattering. For some mixtures, the addition of nanotubes strongly modifies the properties of the matrix: under a magnetic field, the nematic director is aligned perpendicular to the field, whereas it is parallel to it for pure 4-pentyl-4'-cyano-biphenyl. This original modification of liquid crystal alignment by the addition of nanotubes raises new questions about nanotubes and liquid crystal interactions.

Structural characterization of nanotube fibers by x-ray scattering.

Nanotube fibers with diameters ranging between 10 and 100 microns were produced by a simple spinning process. These fibers were studied by x-ray scattering--a technique that allows good visualization of the composition as well as the alignment of the constituents. The fibers were found to be composed of bundles of single wall carbon nanotubes, poly(vinyl alcohol) polymer chains, graphitic objects, and Ni-based particles. The nanotubes and poly(vinyl alcohol) chains were preferentially oriented along the fiber axis.

Anti-leishmania effector functions of CD4+ Th1 cells and early events instructing Th2 cell development and susceptibility to Leishmania major in BALB/c mice.

Resistance and susceptibility to infection with the intracellular parasite, Leishmania major, are mediated by parasite-specific CD4+ Th1 and Th2 cells, respectively. It is well established that the protective effect of parasite-specific CD4+ Th1 cells is largely dependent upon the IFN-gamma produced. However, recent results indicate that the effect of Th1 cells on resolution of lesions induced by L. major in genetically resistant mice also requires a functional Fas-FasL pathway of cytotoxicity. In contrast to resistant mice, susceptible BALB/c mice develop aberrant Th2 responses following infection with L. major and consequently suffer progressive disease. These outcomes clearly depends upon the production of interleukin 4 (IL-4) early after infection. We have shown that a burst of IL-4 mRNA, peaking in draining lymph nodes of BALB/c mice 16 hrs after infection, occurs within CD4+ T cells that express V beta 4-V alpha 8 T cell receptors. In contrast to control and V beta 6-deficient mice, V beta 4-deficient BALB/c mice were resistant to infection, demonstrating the role of these cells in Th2 development. The early IL-4 response was absent in these mice, and Th1 responses occurred following infection. The LACK antigen of L. major induced comparable IL-4 production in V beta 4-V alpha 8 CD4+ T cells. Thus, the IL-4 required for Th2 development and susceptibility to L. major is produced by a restricted population of V beta 4-V alpha 8 CD4+ T cells after cognate interaction with a single antigen from this complex parasite. The IL-4 produced rapidly by these CD4+ T cells induces within 48 hours a state of unresponsiveness to IL-12 among parasite-specific CD4+ T cell precursors by downregulating the IL-12 receptor beta 2 chain expression.

Lymphocyte response in vitro to Plasmodium falciparum merozoite antigens in donors from a holoendemic area.

Crude merozoite antigens from P. falciparum were used to analyse the proliferative response of peripheral blood mononuclear cells from 114 inhabitants of the village of Dielmo (Senegal, West Africa), who are exposed continuously to malaria transmission. The high or low responses to merozoite antigens obtained in lymphocyte stimulation assays were correlated to the presence or absence of parasites, to the IFN-gamma production and to the HLA-phenotype. High responders produced high levels of IFN-gamma while low responders did not secrete IFN-gamma (23/27). The two HLA phenotypes HLA-B51 and HLA-DR1 were significantly associated with high response (p < 0.05).

[Pulmonary tuberculosis and HIV seropositivity at the Principal Hospital of Dakar (Senegal)]. / Tuberculose pulmonaire et séropositivité HIV à l'hôpital principal de Dakar (Sénégal).

In a prospective survey conducted in 1990 in the Principal Hospital of Dakar, pulmonary tuberculosis was 2.3 times more frequent in HIV seropositive patients (12.5%) than in HIV seronegative patients. We studied 22 cases of pulmonary tuberculosis in HIV+ patients and compared them with a control group of HIV- patients admitted for pulmonary tuberculosis. Tuberculosis occurred in 6 out of 22 asymptomatic HIV+ patients, in 15 out of 22 patients with clinical AIDS and in 1 patient with ARC syndrome. Clinical signs were the same as in controls, except for patients with advanced AIDS who developed cardinal signs. TB intra-dermal reactions were more often negative in HIV+ patients, notably those with HDV1, expressing immunodepression. Radiological images were typical in 81% of patients and in 86% of controls. However, concomitant infections were common in both groups, with atypical radiology and hyperleukocytosis. At light microscopy, there was no difference in the frequency of acid and alcohol fast bacilli between the two groups. The mortality rate was increased in HIV+ patients, but this was not due to tuberculosis. Relapses were frequent in both groups, due to poor compliance with treatment.

[Diagnosis of Mycobacterium ulcerans infections in French Guiana]. / Diagnostic de l'infection à Mycobacterium ulcerans en Guyane française.

THE SITUATION: Buruli's ulcer is a severe necrotic cutaneous infection due to Mycobacterium ulcerans. It is a major public health problem in developing countries. FROM A CLINICAL POINT OF VIEW: The early stage of the infection corresponds to a painless cutaneous nodule, whereas the late stage corresponds to ulceration with detachment of the edges. There is currently no other treatment than surgical excision combined with heat therapy. FROM A DIAGNOSTIC POINT OF VIEW: Three methods can be used: direct examination of swabs stained according to Ziehl-Neelsen's method, culture in specific medium at 32 degrees C and the polymerization chain reaction assay (PCR). The latter is the technique of choice.