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1.
Cytokine ; 177: 156562, 2024 05.
Artigo em Inglês | MEDLINE | ID: mdl-38430693

RESUMO

BACKGROUND: Dengue is a rapidly emerging pandemic-prone disease, whose manifestations range from asymptomatic infection to life-threatening complications like Dengue Hemorrhagic Fever and Dengue Shock Syndrome. This study investigates and compares the immune response in clinically defined cohorts of Dengue with and without warning signs, with the aim of identifying immunological correlates of clinical disease and potential markers of disease severity. METHODS: Blood samples, collected from study participants fulfilling the WHO definition of Dengue with and without warning signs and healthy volunteers, were analyzed using flow cell-based fluorometric methods for cytokines and chemokines. Gene expression analysis, using RT-PCR, was conducted on T helper cell subset-specific transcription factors and cytokines. Demographic details, virological markers, serotype distribution, and hematological parameters were also investigated in all the subjects. RESULTS: The 35 participants recruited in the study, included 11 healthy volunteers and 12 patients each fulfilling the WHO criteria of Dengue with and without warning signs. While the demographic characteristics and serotype distribution was similar in Dengue with and without warning signs cohorts of the disease, platelet counts and Aspartate Aminotransferase (AST) levels changed significantly between Dengue with and without warning signs patients. Plasma cytokine analysis showed up-regulation of IL-4, IL-10, IP-10, and MCP-1 in Dengue patients compared to healthy volunteers. Disease severity was associated with elevated levels of IL-10, IP-10, IL-4, MCP-1, and MIP-1α. IL-8 and MIP-1α were significantly up-regulated in Dengue with warning sign compared to Dengue without warning signs cases. Transcription factor analysis indicated increased expression of RORα, FoxP3, and GATA3 in Dengue patients. mRNA expression of TGFß and IL-4 was also elevated in Dengue patients. A positive correlation between mRNA expression of IL-4 and plasma IL-4 was observed. CONCLUSION: The study reveals a Th2-predominant immune response in all Dengue patients, regardless of disease severity, with overexpression of IL-8 and MIP-1α being observed in patients with warning signs.


Assuntos
Dengue , Interleucina-10 , Humanos , Quimiocina CXCL10 , Quimiocina CCL3 , Interleucina-4 , Interleucina-8 , Biomarcadores , Citocinas/metabolismo , Imunidade , RNA Mensageiro
2.
PLoS Pathog ; 17(1): e1009222, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33465168

RESUMO

Bacterial binding to platelets is a key step in the development of infective endocarditis (IE). Sialic acid, a common terminal carbohydrate on host glycans, is the major receptor for streptococci on platelets. So far, all defined interactions between streptococci and sialic acid on platelets are mediated by serine-rich repeat proteins (SRRPs). However, we identified Streptococcus oralis subsp. oralis IE-isolates that bind sialic acid but lack SRRPs. In addition to binding sialic acid, some SRRP- isolates also bind the cryptic receptor ß-1,4-linked galactose through a yet unknown mechanism. Using comparative genomics, we identified a novel sialic acid-binding adhesin, here named AsaA (associated with sialic acid adhesion A), present in IE-isolates lacking SRRPs. We demonstrated that S. oralis subsp. oralis AsaA is required for binding to platelets in a sialic acid-dependent manner. AsaA comprises a non-repeat region (NRR), consisting of a FIVAR/CBM and two Siglec-like and Unique domains, followed by 31 DUF1542 domains. When recombinantly expressed, Siglec-like and Unique domains competitively inhibited binding of S. oralis subsp. oralis and directly interacted with sialic acid on platelets. We further demonstrated that AsaA impacts the pathogenesis of S. oralis subsp. oralis in a rabbit model of IE. Additionally, we found AsaA orthologues in other IE-causing species and demonstrated that the NRR of AsaA from Gemella haemolysans blocked binding of S. oralis subsp. oralis, suggesting that AsaA contributes to the pathogenesis of multiple IE-causing species. Finally, our findings provide evidence that sialic acid is a key factor for bacterial-platelets interactions in a broader range of species than previously appreciated, highlighting its potential as a therapeutic target.


Assuntos
Adesinas Bacterianas/metabolismo , Aderência Bacteriana , Proteínas de Bactérias/metabolismo , Endocardite Bacteriana/patologia , Ácido N-Acetilneuramínico/metabolismo , Streptococcus/metabolismo , Adesinas Bacterianas/genética , Animais , Proteínas de Bactérias/genética , Endocardite Bacteriana/metabolismo , Endocardite Bacteriana/microbiologia , Masculino , Coelhos , Streptococcus/classificação , Streptococcus/genética , Streptococcus/isolamento & purificação
3.
Med J Armed Forces India ; 78(Suppl 1): S312-S314, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36147394

RESUMO

Infectious scleritis is rare and most commonly herpetic in origin. We report an unusual bilateral subacute presentation of scleritis with uveitis and glaucoma which responded to treatment with acyclovir. A 47-year-old male coast guard personnel presented with 2 months history of bilateral red eye. He was initially managed elsewhere as conjunctivitis, and on examination had bilateral diffuse redness of the eyes persisting with phenylephrine, with scleral edema and mild globe tenderness. Investigations for underlying autoimmune systemic illness were normal. He showed inadequate response to topical steroids and cycloplegics and developed uveitis and glaucoma while on steroids. He was then given tablet acyclovir with antiglaucoma topical medications with which he showed rapid response and complete resolution. The case is being reported for highlighting this unusual bilateral presentation of scleritis with uveitis and glaucoma with possible viral etiology.

4.
J Cell Physiol ; 236(12): 8000-8019, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34133758

RESUMO

Viral infections are a major threat to the human population due to the lack of selective therapeutic measures. The morbidity and mortality reported worldwide are very alarming against viral pathogens. The proinflammatory environment is required for viral inhibition by initiating the host immune response. The host immune response fights these pathogens by secreting different cytokines. Interleukin-17 (IL-17) a proinflammatory cytokine mainly produced by T helper type 17 cells, plays a vital role in the regulation of host immune response against various pathogens, including viruses. However, dysregulated production of IL-17 induces chronic inflammation, autoimmune disorders, and may lead to cancer. Recent studies suggest that IL-17 is not only involved in the antiviral immune response but also promotes virus-mediated illnesses. In this review, we discuss the protective and pathogenic role of IL-17 against various viral infections. A detailed understanding of IL-17 during viral infections could contribute to improve therapeutic measures and enable the development of an efficient and safe IL-17 based immunotherapy.


Assuntos
Citocinas/metabolismo , Inflamação/metabolismo , Interleucina-17/metabolismo , Viroses/imunologia , Animais , Doença Crônica , Citocinas/imunologia , Humanos , Interleucina-17/imunologia
5.
Nanotechnology ; 32(8): 085104, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33080579

RESUMO

Nearly 80% of human chronic infections are caused due to bacterial biofilm formation. The increased resistance against the conventional antimicrobial agents makes it difficult to treat the biofilm-related infections. The antibiotics resistance developed by planktonic cells has also become a major threat for human. Therefore, we have attempted here to develop an effective alternative strategy to overcome the issues of antibiotics resistance of bacteria. Upon synthesis, biogenic C-dots were combined with lysozymes which were further encapsulated into chitosan nanocarrier to form C-dots carrier (CDC). The as-synthesized C-dots were found irregular shaped and the average size of C-dots and CDC were 8 ± 2 nm and 450 ± 50 nm, respectively. To ensure secure and targeted delivery of C-dots and lysozyme we have employed chitosan, a biodegradable and natural biopolymer, as a delivery system. The study of time-dependent bacterial growth and flow cytometry analysis demonstrated that CDC can exhibit a synergistic bactericidal activity against the antibiotics resistant recombinant E. coli cells. Further, we have shown that the CDC could be a potent agent for both prevention of biofilm formation and eradication of preformed biofilm. In addition, we have observed that our drug delivery system is hemocompatible in nature making it suitable for in vivo applications. Therefore, we believe that the combination therapy of C-dots and lysozyme may be used as an excellent antibacterial and antibiofilm strategy.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Carbono/química , Muramidase/química , Pontos Quânticos/química , Antibacterianos/química , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Bactérias/ultraestrutura , Carbono/farmacologia , Quitosana/química , Portadores de Fármacos/química , Farmacorresistência Bacteriana/efeitos dos fármacos , Química Verde , Hemólise/efeitos dos fármacos , Humanos , Muramidase/farmacologia
6.
Dig Dis ; 39(5): 516-525, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33429386

RESUMO

BACKGROUND: Chronicity or seroclearance of hepatitis B virus (HBV) antigens is determined by the host immune responses. Current approaches to treat HBV patients are based on inhibition of replication using different antivirals (nucleoside or nucleotide analogs) as monotherapy, or along with immune modulators as combination therapy is being used worldwide for reducing the viral load. Understanding the role of immune cellular therapies with currently available treatments for persistent viral-mediated responses in HBV patients is unexplored. However, the generation of antibodies against a surface (HBs) and envelop (HBe) antigen of hepatitis B remains an issue for future studies and needs to be explored. SUMMARY: Humoral immunity, specifically T follicular helper (TFh) cells, may serve as a target for therapy for HBsAg seroconversion. In this review, we have been engrossed in the importance and role of the humoral immune responses in CHBV infection and vertical transmission. Key Message: TFh cells have been suggested as the potential target of immunotherapy which lead to seroconversion of HBe and HBs antigens of HBV. HBsAg seroconversion and eradication of covalently closed circular DNA are the main challenges for existing and forthcoming therapies in HBV infection.


Assuntos
Hepatite B Crônica , Hepatite B , DNA Viral , Antígenos de Superfície da Hepatite B , Vírus da Hepatite B , Hepatite B Crônica/tratamento farmacológico , Humanos , Imunidade Humoral
7.
Adv Exp Med Biol ; 1353: 23-45, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35137366

RESUMO

INTRODUCTION: After the outbreak from Wuhan City of China, COVID-19, caused by SARS-CoV-2, has become a pandemic worldwide in a very short span of time. The high transmission rate and pathogenicity of this virus have made COVID-19 a major public health concern globally. Basically, the emergence of SARS-CoV-2 is the third introduction of a highly infectious human epidemic coronavirus in the twenty-first century. Various research groups have claimed bats to be the natural host of SARS-CoV-2. However, the intermediate host and mode of transmission from bat to humans are not revealed yet. The COVID-19 cost hundreds and thousands of lives and millions are facing the consequences. The objective of this chapter was to analyze the outbreak of COVID-19 and problems faced globally. METHODS: All published relevant literature from scientific sources and reputed news channels are considered to write the current review. RESULTS: Generally, elder persons and more particularly people with underlying medical conditions are found to be highly vulnerable to severe infection and prone to fatal outcomes. Unfortunately, there is no specific treatment with clinically approved drugs or vaccines to treat this disease. Several research groups have been investigating the efficacies of several antiviral and repurposed drugs. Currently, most of the SARS-COV-2 vaccines are at the preclinical or clinical stage of development. The latest research progress on the epidemiology, clinical characteristics, pathogenesis, diagnosis, and current status of therapeutic intervention indicates that still a specific drug or vaccine needs to come up for the effective treatment of the pandemic COVID-19. It is observed that various aspects of social life, economic status, and healthcare systems are majorly affected by this pandemic. CONCLUSION: It is concluded that the outbreak of COVID-19 has severely affected each and every field, such as social, scientific, industrial, transport, and medical sectors. Irrespective of tremendous efforts globally, few vaccines are now available for the prevention of the disease. Specific drug is not available publicly for the treatment of COVID-19. Prevention of air pollution that can aggravate COVID-19 has been suggested. Therefore, as of now, social distancing and sanitization practices are the only options available for the prevention of the disease for many.


Assuntos
COVID-19 , Idoso , Vacinas contra COVID-19 , Surtos de Doenças , Humanos , Pandemias , SARS-CoV-2
8.
Microbiol Immunol ; 64(10): 694-702, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32816349

RESUMO

Macrophages represent the first line of defense against invading Mycobacterium tuberculosis (Mtb). In order to enhance intracellular survival, Mtb targets various components of the host signaling pathways to limit macrophage functions. The outcome of Mtb infection depends on various factors derived from both host and pathogen. A detailed understanding of such factors operating during interaction of the pathogen with the host is a prerequisite for designing new approaches for combating mycobacterial infections. This work analyzed the role of host phospholipase C-γ1 (PLC-γ1) in regulating mycobacterial uptake and killing by J774A.1 murine macrophages. Small interfering RNA mediated knockdown of PLC-γ1 increased internalization and reduced the intracellular survival of both Mtb and Mycobacterium smegmatis (MS) by macrophages. Down-regulation of the host PLC-γ1 was observed during the course of mycobacterial infection within these macrophages. Finally, Mtb infection also suppressed the expression of pro-inflammatory cytokine tumor necrosis factor-α and chemokine (C-C motif) ligand 5 (RANTES) which was restored by knocking down PLC-γ1 in J774A.1 cells. These observations suggest a role of host PLC-γ1 in the uptake and killing of mycobacteria by murine macrophages.


Assuntos
Quimiocina CCL5/metabolismo , Macrófagos/imunologia , Mycobacterium smegmatis/imunologia , Fagocitose/imunologia , Fosfolipase C gama/genética , Animais , Células Cultivadas , Camundongos , Mycobacterium tuberculosis/imunologia , Fosfolipase C gama/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , Transdução de Sinais/imunologia
9.
Indian J Med Res ; 152(1 & 2): 88-94, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32893844

RESUMO

BACKGROUND & OBJECTIVES: Public health and diagnostic laboratories are facing huge sample loads for COVID-19 diagnosis by real-time reverse transcription-polymerase chain reaction (RT-PCR). High sensitivity of optimized real-time RT-PCR assays makes pooled testing a potentially efficient strategy for resource utilization when positivity rates for particular regions or groups of individuals are low. We report here a comparative analysis of pooled testing for 5- and 10-sample pools by real-time RT-PCR across 10 COVID-19 testing laboratories in India. METHODS: Ten virus research and diagnostic laboratories (VRDLs) testing for COVID-19 by real-time RT-PCR participated in this evaluation. At each laboratory, 100 nasopharyngeal swab samples including 10 positive samples were used to create 5- and 10-sample pools with one positive sample in each pool. RNA extraction and real-time RT-PCR for SARS-CoV-2-specific E gene target were performed for individual positive samples as well as pooled samples. Concordance between individual sample testing and testing in the 5- or 10-sample pools was calculated, and the variation across sites and by sample cycle threshold (Ct) values was analyzed. RESULTS: A total of 110 each of 5- and 10-sample pools were evaluated. Concordance between the 5-sample pool and individual sample testing was 100 per cent in the Ct value ≤30 cycles and 95.5 per cent for Ctvalues ≤33 cycles. Overall concordance between the 5-sample pooled and individual sample testing was 88 per cent while that between 10-sample pool and individual sample testing was 66 per cent. Although the concordance rates for both the 5- and 10-sample pooled testing varied across laboratories, yet for samples with Ct values ≤33 cycles, the concordance was ≥90 per cent across all laboratories for the 5-sample pools. INTERPRETATION & CONCLUSIONS: Results from this multi-site assessment suggest that pooling five samples for SARS-CoV-2 detection by real-time RT-PCR may be an acceptable strategy without much loss of sensitivity even for low viral loads, while with 10-sample pools, there may be considerably higher numbers of false negatives. However, testing laboratories should perform validations with the specific RNA extraction and RT-PCR kits in use at their centres before initiating pooled testing.


Assuntos
Betacoronavirus/isolamento & purificação , Técnicas de Laboratório Clínico , Infecções por Coronavirus/diagnóstico , Pneumonia Viral/diagnóstico , RNA Viral/isolamento & purificação , Betacoronavirus/genética , Betacoronavirus/patogenicidade , COVID-19 , Teste para COVID-19 , Vacinas contra COVID-19 , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/genética , Infecções por Coronavirus/virologia , Testes Diagnósticos de Rotina/métodos , Feminino , Humanos , Índia/epidemiologia , Masculino , Pandemias , Pneumonia Viral/epidemiologia , Pneumonia Viral/genética , Pneumonia Viral/virologia , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , SARS-CoV-2 , Testes Sorológicos , Manejo de Espécimes , Carga Viral/genética
10.
Med J Armed Forces India ; 76(2): 166-171, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32476714

RESUMO

BACKGROUND: Endothelial keratoplasties have become the surgical procedure of choice over full thickness penetrating keratoplasty for corneal decompensation because of endothelial dysfunction. METHODS: A retrospective data review was performed from February 2016 to April 2017 for all the patients who underwent endothelial keratoplasty in a tertiary care center for Indian Armed Forces. RESULTS: A total of 161 corneal transplants were performed; endothelial keratoplasties accounted for 34 (21.1%) transplants. Most common indication was pseudophakic/aphakic bullous keratopathy followed by Ahmed glaucoma valve-related corneal decompensation and Fuchs' corneal dystrophy, respectively. Mean preoperative corneal thickness was 845.96 ± 106.9 microns. Mean lenticule thickness was 131.55 ± 42.47 microns with microkeratome for descemet stripping automated endothelial keratoplasty (DSAEK) and 174 ± 70.4 microns manually for descemet stripping endothelial keratoplasty (DSEK). Mean preoperative best-corrected visual acuity (BCVA) was 1.65 LogMAR (Snellen equivalent in meters 2/60 approx) which significantly improved to 0.82 LogMAR (Snellen equivalent in meters 6/36 approx) after surgery. In the DSAEK group, BCVA improved from 1.61 to 0.7 LogMAR, whereas in the DSEK group, the visual acuity improved from 1.7 to 0.94 LogMAR at one-month postoperative period. Postoperatively, two patients had graft detachment and had to undergo repeat DSAEK. CONCLUSION: Study results suggest the similar trends in our tertiary care hospital as in other most advanced ophthalmic centers around the world for adoption of newer techniques of lamellar corneal transplants and their outcomes.

11.
Infect Immun ; 87(10)2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31308084

RESUMO

Our studies reveal that the oral colonizer and cause of infective endocarditis Streptococcus oralis subsp. dentisani displays a striking monolateral distribution of surface fibrils. Furthermore, our data suggest that these fibrils impact the structure of adherent bacterial chains. Mutagenesis studies indicate that these fibrils are dependent on three serine-rich repeat proteins (SRRPs), here named fibril-associated protein A (FapA), FapB, and FapC, and that each SRRP forms a different fibril with a distinct distribution. SRRPs are a family of bacterial adhesins that have diverse roles in adhesion and that can bind to different receptors through modular nonrepeat region domains. Amino acid sequence and predicted structural similarity searches using the nonrepeat regions suggested that FapA may contribute to interspecies interactions, that FapA and FapB may contribute to intraspecies interactions, and that FapC may contribute to sialic acid binding. We demonstrate that a fapC mutant was significantly reduced in binding to saliva. We confirmed a role for FapC in sialic acid binding by demonstrating that the parental strain was significantly reduced in adhesion upon addition of a recombinantly expressed, sialic acid-specific, carbohydrate binding module, while the fapC mutant was not reduced. However, mutation of a residue previously shown to be essential for sialic acid binding did not decrease bacterial adhesion, leaving the precise mechanism of FapC-mediated adhesion to sialic acid to be defined. We also demonstrate that the presence of any one of the SRRPs is sufficient for efficient biofilm formation. Similar structures were observed on all infective endocarditis isolates examined, suggesting that this distribution is a conserved feature of this S. oralis subspecies.


Assuntos
Proteínas de Bactérias/ultraestrutura , Biofilmes/crescimento & desenvolvimento , Saliva/metabolismo , Ácidos Siálicos/metabolismo , Streptococcus oralis/genética , Sequência de Aminoácidos , Aderência Bacteriana , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Endocardite Bacteriana/microbiologia , Endocardite Bacteriana/patologia , Expressão Gênica , Humanos , Mutação , Ligação Proteica , Domínios Proteicos , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/ultraestrutura , Saliva/química , Ácidos Siálicos/química , Streptococcus oralis/química , Streptococcus oralis/metabolismo
12.
J Environ Manage ; 231: 734-748, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30408767

RESUMO

The continuous increase in water pollution by various organic & inorganic contaminants has become a major issue of concern worldwide. Furthermore, the anthropogenic activities for the manufacturing of various products have boosted this problem manifold. To overcome this serious issue, nanotechnology has initiated to explore various proficient strategies to treat waste water in a more precise and accurate way with the support of various nanomaterials. In recent times, nanosized materials have proved their applicability to provide clean and affordable water treatment technologies. The exclusive features such as high surface area and mechanical properties, greater chemical reactivity, lower cost and energy, efficient regeneration for reuse allow the nanomaterials perfect for water remediation. But the conventional routes of synthesis of nanomaterials encompass the involvement of hazardous and volatile chemicals; therefore the use of nanomaterials further creates the secondary pollution. This issue has intrigued the scientists to develop biogenic pathways and procedures which are environmentally safer and inexpensive. It has led to the new trends that involve developing bio-inspired nano-scale adsorbents and catalysts for the removal and degradation of a wide range of water pollutants. Carbohydrates, proteins, polymers, flavonoids, alkaloids and several antioxidants obtained from plants, bacteria, fungi, and algae have proven their effectiveness as capping and stabilizing agents during manufacture of nanomaterials. Application of biogenic nanomaterials for waste water treatment is relatively newer but rapidly escalating area of research. In the present review, promises and challenges for the synthesis of various biogenic nanomaterials and their potential applications in waste water treatment and/or water purification have been discussed.


Assuntos
Nanoestruturas , Purificação da Água , Nanotecnologia , Águas Residuárias , Poluição da Água
13.
Infect Immun ; 86(7)2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29661931

RESUMO

Streptococcus gordonii is an early colonizer of the oral cavity. Although a variety of S. gordonii adherence mechanisms have been described, current dogma is that the major receptor for S. gordonii is sialic acid. However, as many bacterial species in the oral cavity produce neuraminidase that can cleave terminal sialic acid, it is unclear whether S. gordonii relies on sialic acid for adherence to oral surfaces or if this species has developed alternative binding strategies. Previous studies have examined adherence to immobilized glycoconjugates and identified binding to additional glycans, but no prior studies have defined the contribution of these different glycan structures in adherence to oral epithelial cells. We determined that the majority of S. gordonii strains tested did not rely on sialic acid for efficient adherence. In fact, adherence of some strains was significantly increased following neuraminidase treatment. Further investigation of representative strains that do not rely on sialic acid for adherence revealed binding not only to sialic acid via the serine-rich repeat protein GspB but also to ß-1,4-linked galactose. Adherence to this carbohydrate occurs via an unknown adhesin distinct from those utilized by Streptococcus oralis and Streptococcus pneumoniae Demonstrating the potential biological relevance of binding to this cryptic receptor, we established that S. oralis increases S. gordonii adherence in a neuraminidase-dependent manner. These data suggest that S. gordonii has evolved to simultaneously utilize both terminal and cryptic receptors in response to the production of neuraminidase by other species in the oral environment.


Assuntos
Adesinas Bacterianas/fisiologia , Aderência Bacteriana , Proteínas de Transporte/fisiologia , Ácido N-Acetilneuramínico/fisiologia , Neuraminidase/biossíntese , Streptococcus gordonii/fisiologia , Galactose/metabolismo , Hemaglutininas Virais , Humanos , Mucosa Bucal/microbiologia , Streptococcus oralis/fisiologia
14.
J Nanosci Nanotechnol ; 18(5): 3702-3708, 2018 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-29442887

RESUMO

Herein, we report a greener, total chlorine free, ultrasonic physicochemical process of extraction and purification of cellulose micro-whiskers from rice husk. The initial step involves the treatment of the rice husk with a concentrated aqueous alkali solution for the duration of 6 h at 80 °C in round bottom flask in order to completely dissolve lignin and silica. After alkali pretreatment, the product obtained was thoroughly washed with distilled water, filtered and dried. The dried product was subjected to mechanical treatment followed by a bleaching process. A sonolytic technique was applied for the bleaching of rice husk using Na2O2/H2O2 as a chlorine-free bleaching agent. The detailed mechanism for the ultrasonic physicochemical bleaching of extracted cellulose from rice husk was also proposed. Extracted and bleached cellulose was characterized for morphological, compositional and thermal properties through different characterization techniques.

15.
Infect Immun ; 85(3)2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27993975

RESUMO

Adherence to host surfaces is often mediated by bacterial binding to surface carbohydrates. Although it is widely appreciated that some bacterial species express glycosidases, previous studies have not considered whether bacteria bind to multiple carbohydrates within host glycans as they are modified by bacterial glycosidases. Streptococcus oralis is a leading cause of subacute infective endocarditis. Binding to platelets is a critical step in disease; however, the mechanisms utilized by S. oralis remain largely undefined. Studies revealed that S. oralis, like Streptococcus gordonii and Streptococcus sanguinis, binds platelets via terminal sialic acid. However, unlike those organisms, S. oralis produces a neuraminidase, NanA, which cleaves terminal sialic acid. Further studies revealed that following NanA-dependent removal of terminal sialic acid, S. oralis bound exposed ß-1,4-linked galactose. Adherence to both these carbohydrates required Fap1, the S. oralis member of the serine-rich repeat protein (SRRP) family of adhesins. Mutation of a conserved residue required for sialic acid binding by other SRRPs significantly reduced platelet binding, supporting the hypothesis that Fap1 binds this carbohydrate. The mechanism by which Fap1 contributes to ß-1,4-linked galactose binding remains to be defined; however, binding may occur via additional domains of unknown function within the nonrepeat region, one of which shares some similarity with a carbohydrate binding module. This study is the first demonstration that an SRRP is required to bind ß-1,4-linked galactose and the first time that one of these adhesins has been shown to be required for binding of multiple glycan receptors.


Assuntos
Aderência Bacteriana , Proteínas de Bactérias/metabolismo , Plaquetas/metabolismo , Plaquetas/microbiologia , Neuraminidase/metabolismo , Streptococcus oralis/fisiologia , Galactose/metabolismo , Humanos , Ácido N-Acetilneuramínico/metabolismo , Ligação Proteica , Receptores de Superfície Celular/metabolismo , Streptococcus oralis/enzimologia
16.
Med J Armed Forces India ; 73(2): 129-133, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28924312

RESUMO

BACKGROUND: Infantile esotropia is a convergent strabismus presenting before 6 months of age and is the most common strabismus disorder presenting in the ophthalmology OPD. The dilemma of whether to go for early surgery and how early has been a matter of research for the last 50 years. We describe our results of surgery in infantile esotropia at variable age groups, as well as with different reoperation rates and compare with the results in western literature. METHODS: A prospective study was carried out through a review of 113 cases operated for infantile esotropia between February 2013 and August 2014. The variables studied were: age at surgery, type of fixation, refractive error, associated nystagmus, inferior oblique overaction or dissociated vertical deviation (DVD), type of surgery performed and pre- and postoperative deviation angles. RESULTS: There were 67 male and 46 female cases of infantile esotropia. The age group of patients varied from 6 months to 12 years. Latent nystagmus was seen in 22 cases, inferior oblique overaction in 49 cases and DVD (mild) in 14 cases. Bimedial rectus recession was done in 78 cases and recession-resection in non-dominant eye in remaining 35 cases. The postoperative residual deviation was <10 PD in 102 cases, between 10 and 16 PD in 5 cases and more than 16 PD in 6 cases. Only 6 cases (5.3%) required reoperation for correction of residual deviation. CONCLUSION: The authors recommend surgery before 12 months in all cases of infantile esotropia. The reoperation rates in the current study were considerably low.

17.
PLoS Pathog ; 10(9): e1004364, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25210925

RESUMO

Bacterial cell-surface proteins play integral roles in host-pathogen interactions. These proteins are often architecturally and functionally sophisticated and yet few studies of such proteins involved in host-pathogen interactions have defined the domains or modules required for specific functions. Streptococcus pneumoniae (pneumococcus), an opportunistic pathogen that is a leading cause of community acquired pneumonia, otitis media and bacteremia, is decorated with many complex surface proteins. These include ß-galactosidase BgaA, which is specific for terminal galactose residues ß-1-4 linked to glucose or N-acetylglucosamine and known to play a role in pneumococcal growth, resistance to opsonophagocytic killing, and adherence. This study defines the domains and modules of BgaA that are required for these distinct contributions to pneumococcal pathogenesis. Inhibitors of ß-galactosidase activity reduced pneumococcal growth and increased opsonophagocytic killing in a BgaA dependent manner, indicating these functions require BgaA enzymatic activity. In contrast, inhibitors increased pneumococcal adherence suggesting that BgaA bound a substrate of the enzyme through a distinct module or domain. Extensive biochemical, structural and cell based studies revealed two newly identified non-enzymatic carbohydrate-binding modules (CBMs) mediate adherence to the host cell surface displayed lactose or N-acetyllactosamine. This finding is important to pneumococcal biology as it is the first adhesin-carbohydrate receptor pair identified, supporting the widely held belief that initial pneumococcal attachment is to a glycoconjugate. Perhaps more importantly, this is the first demonstration that a CBM within a carbohydrate-active enzyme can mediate adherence to host cells and thus this study identifies a new class of carbohydrate-binding adhesins and extends the paradigm of CBM function. As other bacterial species express surface-associated carbohydrate-active enzymes containing CBMs these findings have broad implications for bacterial adherence. Together, these data illustrate that comprehending the architectural sophistication of surface-attached proteins can increase our understanding of the different mechanisms by which these proteins can contribute to bacterial pathogenesis.


Assuntos
Aderência Bacteriana , Infecções Pneumocócicas/metabolismo , Streptococcus pneumoniae/enzimologia , beta-Galactosidase/química , beta-Galactosidase/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Cristalografia por Raios X , Inibidores Enzimáticos/metabolismo , Células Epiteliais/enzimologia , Células Epiteliais/imunologia , Interações Hospedeiro-Patógeno , Humanos , Infecções Pneumocócicas/microbiologia , Ligação Proteica , Conformação Proteica , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/crescimento & desenvolvimento
18.
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