Ti64/20Ag Porous Composites Fabricated by Powder Metallurgy for Biomedical Applications.

We present a novel Ti64/20Ag highly porous composite fabricated by powder metallurgy for biomedical applications and provide an insight into its microstructure and mechanical proprieties. In this work, the Ti64/20Ag highly porous composites were successfully fabricated by the space holder technique and consolidated by liquid phase sintering, at lower temperatures than the ones used for Ti64 materials. The sintering densification was evaluated by dilatometry tests and the microstructural characterization and porosity features were determined by scanning electron microscopy and computed microtomography. Permeability was estimated by numerical simulations on the 3D real microstructure. Mechanical properties were evaluated by simple compression tests. Densification was achieved by interparticle pore filling with liquid Ag that does not drain to the large pores, with additional densification due to the macroscopical deformation of large pores. Pore characteristics are closely linked to the pore formers and the permeability was highly increased by increasing the pore volume fraction, mainly because the connectivity was improved. As expected, with the increase in porosity, the mechanical properties decreased. These results permitted us to gain a greater understanding of the microstructure and to confirm that we developed a promising Ti64/20Ag composite, showing E of 7.4 GPa, σy of 123 MPa and permeability of 3.93 × 10-11 m2. Enhanced adaptability and antibacterial proprieties due to Ag were obtained for bone implant applications.

Spatio-temporal characterization of Trypanosoma cruzi infection and discrete typing units infecting hosts and vectors from non-domestic foci of Chile.

BACKGROUND: Trypanosoma cruzi is a protozoan parasite that is transmitted by triatomine vectors to mammals. It is classified in six discrete typing units (DTUs). In Chile, domestic vectorial transmission has been interrupted; however, the parasite is maintained in non-domestic foci. The aim of this study was to describe T. cruzi infection and DTU composition in mammals and triatomines from several non-domestic populations of North-Central Chile and to evaluate their spatio-temporal variations. METHODOLOGY/PRINCIPAL FINDINGS: A total of 710 small mammals and 1140 triatomines captured in six localities during two study periods (summer/winter) of the same year were analyzed by conventional PCR to detect kDNA of T. cruzi. Positive samples were DNA blotted and hybridized with specific probes for detection of DTUs TcI, TcII, TcV, and TcVI. Infection status was modeled, and cluster analysis was performed in each locality. We detected 30.1% of overall infection in small mammals and 34.1% in triatomines, with higher rates in synanthropic mammals and in M. spinolai. We identified infecting DTUs in 45 mammals and 110 triatomines, present more commonly as single infections; the most frequent DTU detected was TcI. Differences in infection rates among species, localities and study periods were detected in small mammals, and between triatomine species; temporally, infection presented opposite patterns between mammals and triatomines. Infection clustering was frequent in vectors, and one locality exhibited half of the 21 clusters found. CONCLUSIONS/SIGNIFICANCE: We determined T. cruzi infection in natural host and vector populations simultaneously in a spatially widespread manner during two study periods. All captured species presented T. cruzi infection, showing spatial and temporal variations. Trypanosoma cruzi distribution can be clustered in space and time. These clusters may represent different spatial and temporal risks of transmission.

Non-motor symptoms and quality of life in patients with Parkinson's disease in Northeastern Mexico.

Parkinson's disease (PD) is a multisystem disorder, and besides the classical motor symptoms it is now known that patients also suffer from a variety of non-motor symptoms that adversely affect quality of life (QOL). Since data on Hispanic populations on this issue are scarce, our aim was to study the association of non-motor symptoms and QOL in patients with PD. This study is a cross-sectional observational study involving patients with PD using the following instruments: Quality of Life Questionnaire (PDQ-8), Unified Parkinson's Disease Rating Scale part III (UPDRS part III), and Non-Motor Symptom Scale (NMSS). We included 52 patients, with a median age of 64 years. Sleep/fatigue and mood/cognitive domains were the most common non-motor symptoms. Only sleep/fatigue, mood/cognition and gastrointestinal domains were associated with worse PDQ-8 scores. After adjusting for confounding variables, NMSS scores were significantly associated with a high PDQ-8 score. Higher NMSS scores were associated with and predicted higher PDQ-8 scores. The focus of management in PD should shift to a comprehensive strategy that incorporates care of non-motor symptoms and improves QOL.

Hemichorea in a patient with HIV-associated central nervous system histoplasmosis.

Central nervous system histoplasmosis is a rare opportunistic infection with a heterogeneous clinical presentation. We describe the first case of human immunodeficiency virus-associated cerebral histoplasmosis presenting with hemichorea. The patient recovered after treatment with conventional amphotericin B and itraconazole.

Drug-induced haemolysis, renal failure, thrombocytopenia and lactic acidosis in patients with HIV and cryptococcal meningitis: a diagnostic challenge.

Patients with HIV are at risk of both primary and secondary haematological disorders. We report two cases of patients with HIV and cryptococcal meningitis who developed severe haemolytic anaemia, thrombocytopenia, renal failure and lactic acidosis while on treatment with amphotericin B and co-trimoxazole.

Proteomic analysis of Schistosoma mansoni egg secretions.

Schistosomiasis remains a largely neglected, global health problem. The morbid pathology of the disease stems from the host's inflammatory response to parasite eggs trapped in host tissues. Long term host/parasite survival is dependent upon the successful modulation of the acute pathological response, which is induced by egg antigens. In this study, using Multidimensional Protein Identification Technology, we identified the Schistosoma mansoni egg secretome consisting of 188 proteins. Notably we identified proteins involved in redox balance, molecular chaperoning and protein folding, development and signaling, scavenging and metabolic pathways, immune response modulation, and 32 novel, previously uncharacterized schistosome proteins. We localized a subset of previously characterized schistosome proteins identified in egg secretions in this study, to the surface of live S. mansoni eggs using the circumoval precipitin reaction. The identification of proteins actively secreted by live schistosome eggs provides important new information for understanding immune modulation and the pathology of schistosomiasis.

Human monoclonal antibodies directed against toxins A and B prevent Clostridium difficile-induced mortality in hamsters.

Clostridium difficile is the leading cause of nosocomial antibiotic-associated diarrhea, and recent outbreaks of strains with increased virulence underscore the importance of identifying novel approaches to treat and prevent relapse of Clostridium difficile-associated diarrhea (CDAD). CDAD pathology is induced by two exotoxins, toxin A and toxin B, which have been shown to be cytotoxic and, in the case of toxin A, enterotoxic. In this report we describe fully human monoclonal antibodies (HuMAbs) that neutralize these toxins and prevent disease in hamsters. Transgenic mice carrying human immunoglobulin genes were used to isolate HuMAbs that neutralize the cytotoxic effects of either toxin A or toxin B in cell-based in vitro neutralization assays. Three anti-toxin A HuMAbs (3H2, CDA1, and 1B11) could all inhibit the enterotoxicity of toxin A in mouse intestinal loops and the in vivo toxicity in a systemic mouse model. Four anti-toxin B HuMAbs (MDX-1388, 103-174, 1G10, and 2A11) could neutralize cytotoxicity in vitro, although systemic toxicity in the mouse could not be neutralized. Anti-toxin A HuMAb CDA1 and anti-toxin B HuMAb MDX-1388 were tested in the well-established hamster model of C. difficile disease. CDA1 alone resulted in a statistically significant reduction of mortality in hamsters; however, the combination treatment offered enhanced protection. Compared to controls, combination therapy reduced mortality from 100% to 45% (P<0.0001) in the primary disease hamster model and from 78% to 32% (P<0.0001) in the less stringent relapse model.

Expansion of CD4 T cells expressing a highly restricted TCR structure specific for a single parasite epitope correlates with high pathology in murine schistosomiasis.

The hepatic immunopathology in schistosomiasis mansoni is mediated by CD4 T cells specific for egg antigens and varies considerably among mouse strains. Previous studies in high pathology C3H mice suggested that a strong T cell response was due to the recognition of an immunodominant epitope within the major egg antigen Sm-p40 (Sm-p40(234-246)). Using a panel of T cell hybridomas, we have now examined the egg antigen-specific TCR repertoire in two high pathology strains, C3H and CBA. We found that nearly half of the hybridomas responded to the Sm-p40(234-246 )epitope and, of these, nearly all expressed Valpha11.3 associated with Vbeta8. Furthermore, in response to egg antigen stimulation, transcript levels of Valpha11.3J36 (the most prevalent rearrangement expressed by Sm-p40(234-246)-specific hybridomas), increased in high pathology (CBA) but not in low pathology BALB/c strains. Our findings suggest that exacerbated schistosome egg-induced immunopathology can be driven by T cells expressing a highly restricted TCR structure specific for a single parasite epitope.

Development and characterization of a severe acute respiratory syndrome-associated coronavirus-neutralizing human monoclonal antibody that provides effective immunoprophylaxis in mice.

BACKGROUND: Severe acute respiratory syndrome (SARS) remains a significant public health concern after the epidemic in 2003. Human monoclonal antibodies (MAbs) that neutralize SARS-associated coronavirus (SARS-CoV) could provide protection for exposed individuals. METHODS: Transgenic mice with human immunoglobulin genes were immunized with the recombinant major surface (S) glycoprotein ectodomain of SARS-CoV. Epitopes of 2 neutralizing MAbs derived from these mice were mapped and evaluated in a murine model of SARS-CoV infection. RESULTS: Both MAbs bound to S glycoprotein expressed on transfected cells but differed in their ability to block binding of S glycoprotein to Vero E6 cells. Immunoprecipitation analysis revealed 2 antibody-binding epitopes: one MAb (201) bound within the receptor-binding domain at aa 490-510, and the other MAb (68) bound externally to the domain at aa 130-150. Mice that received 40 mg/kg of either MAb prior to challenge with SARS-CoV were completely protected from virus replication in the lungs, and doses as low as 1.6 mg/kg offered significant protection. CONCLUSIONS: Two neutralizing epitopes were defined for MAbs to SARS-CoV S glycoprotein. Antibodies to both epitopes protected mice against SARS-CoV challenge. Clinical trials are planned to test MAb 201, a fully human MAb specific for the epitope within the receptor-binding region.

Enhanced egg-induced immunopathology correlates with high IFN-gamma in murine schistosomiasis: identification of two epistatic genetic intervals.

The genetic basis of dissimilar immunopathology development among mouse strains infected with Schistosoma mansoni is not known. We performed a multipoint parametric linkage analysis on a cohort of F(2) mice, offspring of brother-sister mating between (high pathology CBA x low pathology BL/6)F(1) mice, to examine whether the observed differences in the type of immune response or the extent of hepatic immunopathology are linked to any particular genomic intervals. The F(2) mice exhibited cytokine responses and immunopathologies that revealed a statistically significant correlation between prominent egg Ag-stimulated IFN-gamma production by mesenteric lymph node cells and hepatic egg granuloma size. Increased IFN-gamma production showed suggestive linkage to a dominant CBA locus on chromosome 1 and a recessive CBA locus on chromosome 5; significantly, there was an epistatic interaction between the two IFN-gamma loci. An additional locus with suggestive linkage to granuloma formation and a CBA-recessive mode of inheritance was mapped to centromeric chromosome 13. Our analysis identified the first three genetic regions that appear to influence the immunopathology in murine schistosomiasis; however, further congenic dissection studies will furnish a more precise understanding of the genetic control of this disease.

The immunobiology of Th1 polarization in high-pathology schistosomiasis.

Schistosomiasis is a serious global helminthic disease, in which the main immunopathology consists of a granulomatous and fibrosing reaction against tissue-trapped parasite eggs. The severity of this inflammatory process, the product of a CD4(+) T-cell-mediated immune response against parasite egg antigens, is, however, markedly uneven, both in human patients and among mouse strains in an experimental model. Severe schistosomiasis is associated with persistently elevated pro-inflammatory T-helper-1 (Th1)-type cytokines, whereas milder pathology is present when Th2 cytokines dominate. This scenario is supported by the pronounced pathology resulting from the obliteration of pathways that facilitate Th2 differentiation and by the development of more intense lesions in mouse strains that fail to downregulate the Th1 response. Genetically prone high-pathology mice have a higher proportion of CD4(+) T cells in lymph nodes and granulomas, in which the Th1 phenotype is driven by interleukin-12; they also develop a dominant repertoire against peptide 234-246 of the major Sm-p40 egg antigen, utilizing a strikingly restricted T-cell receptor structure that involves Valpha11.3beta8. In turn, low-pathology mice exhibit enhanced CD4(+) T-cell apoptosis, which contributes to limit pathology. The definition of distinctive immune profiles associated with polar forms of schistosomiasis opens opportunities for targeted immuno-intervention in individuals suffering from or at risk of severe disease.

Diminished immunopathology in Schistosoma mansoni infection following intranasal administration of cholera toxin B-immunodominant peptide conjugate correlates with enhanced transforming growth factor-beta production by CD4 T cells.

In Schistosoma mansoni infection, CD4 T cells specific for parasite egg antigens mediate perioval granuloma formation in the liver and intestines. Mice of the CBA strain develop a severe form of disease and a significant proportion of their CD4 T cell response is directed against the major egg antigen Sm-p40 and its immunodominant T cell epitope peptide 234-246. Here, we show that intranasal (i.n.) treatment of infected CBA mice with a fusion protein of the cholera toxin B subunit (CTB) with peptide 234-246 (CTB::pep) results in significant down-modulation of hepatic granulomatous inflammation and fibrosis. Moreover, egg antigen-stimulated dispersed hepatic granuloma cells, as well as mesenteric lymph node CD4 T cells from the CTB::pep-treated mice, produced significantly more transforming growth factor (TGF)-beta than that produced by treated or untreated controls. The data demonstrate that i.n. administration of a single immunodominant peptide conjugated to CTB can lead to down-regulation of the hepatic immunopathology associated with schistosomiasis, and that this down-regulation is, at least in part, mediated by TGF-beta.

The identification and characterization of new immunogenic egg components: implications for evaluation and control of the immunopathogenic T cell response in schistosomiasis

In schistosomiasis, granuloma formation to parasite eggs signals the beginning of a chronic and potentially life-threatening disease. Granulomas are strictly mediated by CD4+ T helper (Th) cells specific for egg antigens; however, the number and identity of these T cell-sensitizing molecules are largely unknown. We have used monoclonal T cell reagents derived from egg-sensitized individuals as probes to track down, isolate and positively identify several egg antigens; this approach implicitly assures that the molecules of interest are T cell immunogens and, hence, potentially pathogenic. The best studied and most abundant egg component is the Sm-p40 antigen. Sm-p40 and its peptide 234-246 elicit a strikingly immunodominant Th-1-polarized response in C3H and CBA mice, which are H-2k strains characterized by severe egg-induced immunopathology. Two additional recently described T cell-sensitizing egg antigens are Schistosoma mansoni phosphoenolpyruvate carboxykinase (Sm-PEPCK) and thioredoxin peroxidase-1 (Sm-TPx-1). In contrast to Sm-p40, both of these molecules induce a more balanced Th-1/Th-2 response, and are relatively stronger antigens in C57BL/6 mice, which develop smaller egg granulomas. Importantly, Sm-p40 and Sm-PEPCK have demonstrated immunogenicity in humans. The findings in the murine model introduce the important notion that egg antigens can vary significantly in immunogenicity according to the host's genetic background. A better knowledge of the principal immunogenic egg components is necessary to determine whether the immune responses to certain antigens can serve as indicators or predictors of the form and severity of clinical disease, and to ascertain whether such responses can be manipulated for the purpose of reducing pathology