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"Samanta, C."
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Validation of energy conditions in wormhole geometry within viable f(R) gravity
2019
In this work, wormholes, tunnel like structures introduced by Morris and Thorne (Am J Phys 56:395, 1988), are explored within the framework of f(R) gravity. Using the shape function \\[b(r)=r_0\\big (\\frac{r}{r_0}\\big )^\\gamma \\], where \\[0<\\gamma <1\\], and the equation of state \\[p_r=\\omega \\rho \\], the f(R) function is derived and the field equations are solved. Then null, weak, strong and dominated energy conditions are analyzed and spherical regions satisfying these energy conditions are determined. Furthermore, we calculated the range of the radius of the throat of the wormhole, where the energy conditions are satisfied.
Journal Article
Stability analysis for cosmological models in f(R) gravity using dynamical system analysis
2019
Modified gravity theories have received increased attention lately to understand the late time acceleration of the universe. This viewpoint essentially modifies the geometric components of the universe. Among numerous extension to Einstein’s theory of gravity, theories which include higher order curvature invariant, and specifically the class of f(R) theories, have received several acknowledgments. In our current work we try to understand the late time acceleration of the universe by modifying the geometry of the space and using dynamical system analysis. The use of this technique allows to understand the behavior of the universe under several circumstances. Apart from that we study the stability properties of the critical point and acceleration phase of the universe which could then be analyzed with observational data. We consider a particular model \\[f(R) = R - \\mu R_{c}(R/R_{c})^{p}\\] with \\[ 0< p < 1, \\mu , R_{c} > 0\\] for the study. As a first case we consider the matter and radiation component of the universe with an assumption of no interaction between them. Later, as a second case we take matter, radiation and dark energy (cosmological constant) where study on effects of linear, non-linear and no interaction between matter and dark energy is considered and results have been discussed in detail.
Journal Article
Naturally Derived Heme-Oxygenase 1 Inducers and Their Therapeutic Application to Immune-Mediated Diseases
by
Kalergis, Alexis M.
,
Mackern-Oberti, Juan Pablo
,
Fernández-Fierro, Ayleen
in
Abietanes - therapeutic use
,
Animals
,
Autoimmune diseases
2020
Heme oxygenase (HO) is the primary antioxidant enzyme involved in heme group degradation. A variety of stimuli triggers the expression of the inducible HO-1 isoform, which is modulated by its substrate and cellular stressors. A major anti-inflammatory role has been assigned to the HO-1 activity. Therefore, in recent years HO-1 induction has been employed as an approach to treating several disorders displaying some immune alterations components, such as exacerbated inflammation or self-reactivity. Many natural compounds have shown to be effective inductors of HO-1 without cytotoxic effects; among them, most are chemicals present in plants used as food, flavoring, and medicine. Here we discuss some naturally derived compounds involved in HO-1 induction, their impact in the immune response modulation, and the beneficial effect in diverse autoimmune disorders. We conclude that the use of some compounds from natural sources able to induce HO-1 is an attractive lifestyle toward promoting human health. This review opens a new outlook on the investigation of naturally derived HO-1 inducers, mainly concerning autoimmunity.
Journal Article
Dynamics of antimicrobial resistance of Streptococcus pneumoniae following PCV10 introduction in Brazil: Nationwide surveillance from 2007 to 2019
by
Berezin, Eitan N.
,
Harrison, Lee H.
,
Brandileone, Maria-Cristina C.
in
Age groups
,
Allergy and Immunology
,
antibiotic resistance
2021
Brazil introduced 10-valent pneumococcal conjugate vaccine (PCV10) into its immunization program in 2010. We assessed antimicrobial susceptibility of Streptococcus pneumoniae (Spn) obtained from a national surveillance system for invasive pneumococcal diseases (IPD) before/after PCV10 introduction.
Antimicrobial non-susceptible isolates were defined as intermediate or resistant. Minimum inhibitory concentrations (MICs) to penicillin and ceftriaxone were analyzed by year. Antimicrobial susceptibility rates were assessed for each three-year-period using the pre-PCV10-period as reference. Susceptibility of vaccine-types was evaluated for 2017–2019.
11,380 isolates were studied. Spn with penicillin ≥ 0.125 mg/L and ceftriaxone ≥ 1.0 mg/L decreased in the three-years after PCV10 introduction (2011–2013: penicillin, 28.1–22.5%; ceftriaxone, 11.3%-7.6%) versus pre-PCV10-years (2007–2009: penicillin, 33.8–38.1%; ceftriaxone, 17.2%-15.6%). After 2013, the proportion of Spn with those MICs to penicillin and ceftriaxone increased to 39.4% and 19.7% in 2019, respectively. Non-susceptibility to penicillin and ceftriaxone increased in 2014–2016, and again in 2017–2019 especially among children < 5 years with meningitis (penicillin, 53.9%; ceftriaxone, 28.0%); multidrug-resistance reached 25% in 2017–2019. Serotypes 19A, 6C and 23A were most associated with antimicrobial non-susceptibility.
Antimicrobial non-susceptible Spn decreased in the three-years after vaccination but subsequently increased and was associated with non-PCV10-types. Antimicrobial susceptibility surveillance is fundamental for guiding antibiotic therapy policies.
Journal Article
Distribution of invasive Streptococcus pneumoniae serotypes before and 5 years after the introduction of 10-valent pneumococcal conjugate vaccine in Brazil
by
Brandileone, Maria-Cristina C.
,
Minamisava, Ruth
,
Andrade, Ana-Lucia
in
10-valent pneumococcal conjugate vaccine
,
Adolescent
,
Adult
2018
•PCV10 reduced IPD caused by vaccine serotypes of Streptococcus pneumoniae.•PCV10 reduced IPD by vaccine serotypes in the non-targeted population.•IPD by serotypes 3, 6C, and 19A increased after the introduction of PCV10.
In March 2010, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced into the routine immunization program in Brazil. We describe the pneumococcal serotypes that caused invasive pneumococcal diseases (IPD) before and after the introduction of PCV10 using data from a national laboratory-based surveillance system.
We compared the prevalence of vaccine types (VT) and non-vaccine types (NVT) of Streptococcus pneumoniae in three periods, pre-PCV10 (January/2005-December/2009), early post-PCV10 (January/2010-December/2013), and late post-PCV10 (January/2014-December/2015), by episode in meningitis and non-meningitis cases and by age group. Changes in serotype prevalence in the early and late post-PCV10 periods were determined using pre-PCV10 period as a reference.
A total of 8971 IPD isolates from patients aged 2 months to 99 years were analyzed. In the late post-PCV10 period, the VT-IPD reduction in the 2-month to 4-year age group was 83.4% for meningitis and 87.4% for non-meningitis cases; in the age groups 5–17 years, 18–64 years, and ≥65 years, VT declined by 56.1%, 54.1%, and 47.4%, respectively, in meningitis cases, and by 60.9%, 47.7%, and 53.4%, respectively, in non-meningitis cases. NVT-IPD increased throughout the study period, driven mainly by serotypes 3, 6C, and 19A, which remained the predominant types causing IPD in the late post-PCV10 period.
We observed direct and indirect PCV10 protection against IPD caused by VT and a shift in the distribution of serotypes 5 years after the introduction of PCV10. Continued IPD surveillance is needed to evaluate the sustainability of the high prevalence of serotypes 3, 6C, and 19A, which were not included in PCV10.
Journal Article
Compact bifluid hybrid stars: hadronic matter mixed with self-interacting fermionic asymmetric dark matter
2017
The masses and radii of non-rotating and rotating configurations of pure hadronic stars mixed with self-interacting fermionic asymmetric dark matter are calculated within the two-fluid formalism of stellar structure equations in general relativity. The Equation of State (EoS) of nuclear matter is obtained from the density dependent M3Y effective nucleon–nucleon interaction. We consider the dark matter particle mass of 1 GeV. The EoS of self-interacting dark matter is taken from two-body repulsive interactions of the scale of strong interactions. We explore the conditions of equal and different rotational frequencies of nuclear matter and dark matter and find that the maximum mass of differentially rotating stars with self-interacting dark matter to be
∼
1.94
M
⊙
with radius
∼
10.4
km.
Journal Article
A lineage-specific rapid diagnostic test (Chagas Sero K-SeT) identifies Brazilian Trypanosoma cruzi II/V/VI reservoir hosts among diverse mammalian orders
by
Murphy, Niamh
,
McClean, Mairi C. W.
,
Jansen, Ana M.
in
Animals
,
Antibodies
,
Antigenic determinants
2020
Trypanosoma cruzi, the protozoan agent of Chagas disease in the Americas, is comprised of six genetic lineages (TcI-TcVI) and a possible seventh (TcBat, related to TcI). Identification of T. cruzi lineages infecting reservoir mammalian species is fundamental to resolving transmission cycles. However, this is hindered by the limited sensitivity and technical complexity of parasite isolation and genotyping. An alternative approach is serology using T. cruzi lineage-specific epitopes, such as those of the trypomastigote small surface antigen (TSSA). For surveillance of T. cruzi lineage infections in mammal species from diverse Brazilian regions, we apply a novel rapid diagnostic test (RDT, Chagas Sero K-SeT), which incorporates the TSSA peptide epitope specific to TcII/V/VI (TSSApep-II/V/VI) and Protein G detection of antibodies. Chagas Sero K-SeT RDT results with sera from experimentally infected mice, from tamarin primates (Leontopithecus spp.) and from canines (Canis familiaris) were concordant with corresponding TSSApep-II/V/VI ELISAs. The Chagas Sero K-Set detected TcII/V/VI infections in Leontopithecus spp. from the Atlantic forest (n = 46), in C. familiaris (n = 16) and Thrichomys laurentius (n = 2) from Caatinga biome and Chiroptera (n = 1) from Acre, Amazonia. The Chagas Sero K-SeT RDT is directly applicable to TcII/V/VI-specific serological surveillance of T. cruzi infection in several different mammalian Orders. It can replace ELISAs and provides efficient, point-of-sampling, low-cost detection of TcII/V/VI infections, with at least equivalent sensitivity, although some mammals may be difficult to trap, and, not unexpectedly, Chagas Sero K-SeT could not recognise feline IgG. Knowledge of sylvatic hosts of T. cruzi can be expanded, new reservoir species discovered, and the ecology of transmission cycles clarified, particularly with adaptation to further mammalian Orders.
Journal Article
Vegetation cover and biodiversity reduce parasite infection in wild hosts across ecological levels and scales
by
Martinez‐Vaquero, Luis A.
,
Winck, Gisele R.
,
Xavier, Samanta C. C.
in
Abundance
,
allometry
,
Anthropogenic factors
2023
Land use changes and biodiversity loss critically disrupts ecosystem functioning and are major drivers of infectious disease outbreaks. Trypanosoma cruzi, the agent of Chagas disease, is a multi‐host parasite whose epidemiology has changed due to the expansion of anthropogenic activities over natural areas. We aimed to understand the ecological processes increasing parasite prevalence at the individual, the community and the landscape levels using the largest database on small mammal infection by T. cruzi in Brazil. We applied machine learning techniques and structural equation models to show that allometric traits and the relative abundance of rodents in the community were important predictors of infection risk, followed by variables associated with the landscape environmental quality. Natural vegetation cover change and the taxonomic and functional dimensions of biodiversity indirectly reduced infection through its effect on the abundance distribution and composition of host communities. According to our findings, approaches to biodiversity conservation and restoration based on the integration of social inclusion and human welfare would contribute to regulate the prevalence of T. cruzi in wild hosts, which may reduce overall transmission risk.
Journal Article
Long-term effect of 10-valent pneumococcal conjugate vaccine on nasopharyngeal carriage of Streptococcus pneumoniae in children in Brazil
by
Brandileone, Maria-Cristina de C.
,
Higa, Fábio T.
,
Zanella, Rosemeire C.
in
Allergy and Immunology
,
Brazil
,
Cefotaxime
2019
•After 7 years of PCV10 introduction, vaccine type colonization among toddlers decreased.•After 7 years of PCV10 introduction non-PCV10-type increased mainly serotypes 19A and 6C.•Increase in serotype 19A was associated with antibiotic-resistant clonal complex CC320.
Brazil introduced the 10-valent pneumococcal vaccine (PCV10) to the routine national immunization program (NIP) in March 2010. In 2017, we investigated the effects of PCV10 on nasopharyngeal carriage of vaccine-types (VT) and non-vaccine-types (NVT) of Streptococcus pneumoniae (Spn) among children living in São Paulo city. We also compared the prevalence of VT and NVT with previous carriage surveys performed in 2010 (baseline) and 2013.
The carriage survey was conducted among 531 children, aged 12 months to <24 months, recruited from public Primary Health Units during the immunization campaign, using previous surveys methodology, except for qPCR, which was performed in the 2017 survey only.
No statistical difference was found in the prevalence of Spn either by culture (59.7%) or by qPCR (61.2%). Spn carriage increased from 40.3% (baseline) to 59.7% (2017 survey) (p < 0.001). Colonization by VT isolates significantly decreased by 90.9% (19.8–1.8%) and 95.5% (19.8–0.9%) in the 2013 and 2017 surveys, respectively, compared to that at baseline. NVT isolates increased significantly by 128% (19.6–44.8%) and 185% (19.6–55.9%) in the respective post-PCV10 surveys, most led to high prevalence of serotypes 6C (27%), 15B (9.8%), 19A (9.2%), 15A (6.0%), and 16F (5.7%). In 2017, reduction in serotype 6A (4.2–0.6%, p < 0.001) and increase in serotype 19A (1.8–6.0%, p = 0.001) were found; serotype 3 isolate was not detected in the present survey. We identified the emergence of 19A isolates CC320, associated with high penicillin (MIC ≥ 2.0 mg/L) and cefotaxime (MIC ≥ 1.0 mg/L) values.
After 7 years of PCV10 introduction in the NIP, colonization by VT among toddlers decreased substantially to a residual level, along with substantial serotype replacement by novel serotypes not present in any current conjugated pneumococcal vaccine and serotype 19A. The present findings can assist policy decisions in Brazil.
Journal Article
Spatial and Molecular Epidemiology of Giardia intestinalis Deep in the Amazon, Brazil
by
Coronato Nunes, Beatriz
,
Carvalho-Costa, Filipe A.
,
Xavier, Samanta C. C.
in
Adolescent
,
Biology and Life Sciences
,
Brazil - epidemiology
2016
Current control policies for intestinal parasitosis focuses on soil-transmitted helminths, being ineffective against Giardia intestinalis, a highly prevalent protozoon that impacts children's nutritional status in developing countries. The objective of this study was to explore spatial and molecular epidemiology of Giardia intestinalis in children of Amerindian descent in the Brazilian Amazon.
A cross sectional survey was performed in the Brazilian Amazon with 433 children aged 1 to 14 years. Fecal samples were processed through parasitological techniques and molecular characterization. Prevalence of G. intestinalis infection was 16.9% (73/433), reaching 22.2% (35/158) among children aged 2-5 years, and a wide distribution throughout the city with some hot spots. Positivity-rate was similar among children living in distinct socioeconomic strata (48/280 [17.1%] and 19/116 [16.4%] below and above the poverty line, respectively). Sequencing of the β-giardin gene revealed 52.2% (n = 12) of assemblage A and 47.8% (n = 11) of assemblage B with high haplotype diversity for the latter. The isolates clustered into two well-supported G. intestinalis clades. A total of 38 haplotypes were obtained, with the following subassemblages distribution: 5.3% (n = 2) AII, 26.3% (n = 10) AIII, 7.9% (n = 3) BIII, and 60.5% (n = 23) new B genotypes not previously described.
Giardia intestinalis infection presents a high prevalence rate among Amerindian descended children living in Santa Isabel do Rio Negro/Amazon. The wide distribution observed in a small city suggests the presence of multiple sources of infection, which could be related to environmental contamination with feces, possibly of human and animal origin, highlighting the need of improving sanitation, safe water supply and access to diagnosis and adequate treatment of infections.
Journal Article