Recent Advances in the Development of Monoclonal Antibodies and Next-Generation Antibodies

mAbs are highly indispensable tools for diagnostic, prophylactic, and therapeutic applications. The first technique, hybridoma technology, was based on fusion of B lymphocytes with myeloma cells, which resulted in generation of single mAbs against a specific Ag. Along with hybridoma technology, several novel and alternative methods have been developed to improve mAb generation, ranging from electrofusion to the discovery of completely novel technologies such as B cell immortalization; phage, yeast, bacterial, ribosome, and mammalian display systems; DNA/RNA encoded Abs; single B cell technology; transgenic animals; and artificial intelligence/machine learning. This commentary outlines the evolution, methodology, advantages, and limitations of various mAb production techniques. Furthermore, with the advent of next-generation Ab technologies such as single-chain variable fragments, nanobodies, bispecific Abs, Fc-engineered Abs, Ab biosimilars, Ab mimetics, and Ab-drug conjugates, the healthcare and pharmaceutical sectors have become resourceful to develop highly specific mAb treatments against various diseases such as cancer and autoimmune and infectious diseases.

Diagnostic Utility of 3D Gradient-Echo MR Imaging Sequences through the Filum Compared with Spin-Echo T1 in Children with Concern for Tethered Cord

BACKGROUND AND PURPOSE

Fatty intrathecal lesions are a cause of tethered cord, and detection of these on spinal MR imaging is paramount. Conventional T1 FSE sequences are the mainstay of detecting fatty elements; however, 3D gradient-echo MR images, volumetric interpolated breath-hold examination/liver acquisition with volume acceleration (VIBE/LAVA), are popular, given the increased motion resistance. We sought to evaluate the diagnostic accuracy of VIBE/LAVA compared with T1 FSE for detection of fatty intrathecal lesions.

MATERIALS AND METHODS

In this retrospective, institutional review board-approved study, 479 consecutive pediatric spine MRIs obtained to evaluate cord tethering between January 2016 and April 2022 were reviewed. Inclusion criteria were patients who were 20 years of age or younger who underwent spine MRIs containing both axial T1 FSE and VIBE/LAVA sequences of the lumbar spine. The presence or absence of fatty intrathecal lesions was recorded for each sequence. If fatty intrathecal lesions were present, anterior-posterior and transverse dimensions were recorded. VIBE/LAVA and T1 FSE sequences were evaluated on 2 separate occasions (VIBE/LAVAs first followed by T1 FSE several weeks later) to minimize bias. Basic descriptive statistics compared fatty intrathecal lesion sizes on T1 FSEs and VIBE/LAVAs. Receiver operating characteristic curves were used to determine minimal fatty intrathecal lesion size detectable by VIBE/LAVA.

RESULTS

Sixty-six patients were included, with 22 having fatty intrathecal lesions (mean age, 7.2 years). T1 FSE sequences revealed fatty intrathecal lesions in 21/22 cases (95%); however, fatty intrathecal lesions on VIBE/LAVA were detected in 12/22 patients (55%). Mean anterior-posterior and transverse dimensions of fatty intrathecal lesions measured larger on T1 FSE compared with VIBE/LAVA sequences (5.4 × 5.0 mm versus 1.5 × 1.6 mm, respectively; P values = .039 anterior-posterior; .027 transverse).

CONCLUSIONS

While T1 3D gradient-echo MR images may have decreased the acquisition time and are more motion-resistant than conventional T1 FSE sequences, they are less sensitive and may miss small fatty intrathecal lesions.

Host-parasite interactions during Plasmodium infection: Implications for immunotherapies

Malaria is a global infectious disease that remains a leading cause of morbidity and mortality in the developing world. Multiple environmental and host and parasite factors govern the clinical outcomes of malaria. The host immune response against the Plasmodium parasite is heterogenous and stage-specific both in the human host and mosquito vector. The Plasmodium parasite virulence is predominantly associated with its ability to evade the host's immune response. Despite the availability of drug-based therapies, Plasmodium parasites can acquire drug resistance due to high antigenic variations and allelic polymorphisms. The lack of licensed vaccines against Plasmodium infection necessitates the development of effective, safe and successful therapeutics. To design an effective vaccine, it is important to study the immune evasion strategies and stage-specific Plasmodium proteins, which are targets of the host immune response. This review provides an overview of the host immune defense mechanisms and parasite immune evasion strategies during Plasmodium infection. Furthermore, we also summarize and discuss the current progress in various anti-malarial vaccine approaches, along with antibody-based therapy involving monoclonal antibodies, and research advancements in host-directed therapy, which can together open new avenues for developing novel immunotherapies against malaria infection and transmission.

P394 Evaluation of diagnostic potential of recombinant secretory aspartyl proteinase 2 (Sap2) protein from Candida parapsilosis for use in systemic candidiasis

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM

 

Objectives

Systemic candidiasis is the fourth most common bloodstream infection in ICU patients worldwide. Along with Candida albicans, infections caused by non-albicans Candida (NAC) species are increasingly becoming more prevalent globally along with the emergence of drug resistance. The diagnosis of systemic candidiasis is difficult due to the absence of significant clinical symptoms in patients. Since conventional diagnostics methods for candidiasis show less sensitivity and specificity, novel immunodiagnostic techniques are needed for early diagnosis. We investigated the diagnostic potential of recombinant secreted aspartyl proteinase 2 (rSap2) from C. parapsilosis for the detection of Candida infection.

Methods

Genomic DNA was isolated from C. parapsilosis, followed by PCR amplification of Sap2 gene using designed gene-specific primers. Sap2 protein expression and purification was performed using Ni-NTA affinity chromatography under denaturing conditions. The denatured protein was subsequently refolded using a multi-step dialysis procedure. CD and FTIR studies were performed to confirm refolding. Mice were immunized with rSap2 protein and serum ELISA assays were performed for testing immunogenicity. Immunoblotting assays and human serum ELISAs were performed using whole-cell Candida and rSap2 protein in proven systemic candidiasis patient serum and controls, recruited at PGIMER, Chandigarh.

Results

Sap2 protein from C. parapsilosis was successfully cloned and expressed using an E. coli-based prokaryotic expression system. Protein refolding was performed in vitro using step-wise dialysis. Structural analysis by CD and FTIR spectroscopy revealed the refolded protein to be in its near native conformation. Immunogenicity analysis demonstrated the rSap2 protein to be highly immunogenic as evident from significantly high titers of Sap2-specific antibodies in antigen immunized BALb/c mice, compared to sham-immunized controls. The diagnostic potential of rSap2 protein was evaluated using immunoblotting and ELISA assays using serum from proven systemic candidiasis patients and controls. Our immunoblotting results demonstrate that the recombinant Sap2 protein was recognized as a single band of approximately 41 kDa by systemic candidiasis patient serum samples and no cross reactivity was observed in healthy controls. On evaluating the diagnostic potential of the rSap2 antigen using an ELISA-based approach, our results show that anti-Sap2 Ig, IgG and IgM antibodies could be detected in the sera of proven candidiasis patients. Of note, the differences in Sap2 antibody titers observed amongst patients and controls were similar to the serological response observed when heat-killed whole-cell Candida was used as a coating antigen.

Conclusion

In summary, the rSap2 protein from C. parapsilosis has the potential to be used in the diagnosis of systemic candidiasis, providing a rapid, convenient, accurate, and cost-effective strategy. Our results indicate that the rSap2 protein from C. parapsilosis can be used to detect and diagnose systemic candidiasis infection in human patients and can be used as an alternative/replacement of whole-cell Candida-based ELISA procedures, which are currently in use.

P120 Vaccine induced protection by secreted aspartyl proteinase 2 from Candida parapsilosis in Candida tropicalis mediated murine systemic candidiasis: a role of B-cells and antibodies

 

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

Objectives

Non-albicans Candida species are increasingly becoming more prevalent globally and emergence of drug resistance is another cause of concern. These challenges merit the need for developing novel immune therapies against Candida infections. We investigated the protective potential of secreted aspartyl proteinase (Sap2), a leading Candidate vaccine antigen identified from research based on C. albicans, in murine systemic candidiasis caused by non-albicans Candida species. Moreover, while the role of cellular immune responses in anti-Candida immunity is well established, less is known about the role of humoral immunity against systemic candidiasis. As such, we also investigated the role of humoral immunity in vaccine-mediated protection during murine systemic candidiasis.

Methods

The Sap2 genes were successfully cloned and expressed as recombinant proteins from C. albicans, C. tropicalis and C. parapsilosis strains prevalent in India. Groups of wild-type BALb/c mice were vaccinated with individual rSap2 protein along with alum as adjuvant, followed by systemic infection with a lethal dose of C. tropicalis. The protective potential of each rSap2 protein was evaluated using survival analysis and estimation of organ fungal burden. Histopathological assessment was performed using H&E and PAS staining. Serum cytokine levels and antigen-specific antibody titers were measured by ELISA. Cellular responses were analyzed in detail using flow cytometry. Functional evaluation of antibody role was performed using in vitro (biofilm inhibition and neutrophil-mediated killing) and in vivo (passive transfer) studies. B-cell epitope analysis was carried out using immunoinformatics approaches.

Results

Mice vaccinated with rSap2 cloned from C. parapsilosis (Sap2-parapsilosis) showed highest increase in survival time (P = .02) and maximum reduction in organ fungal burden (spleen, kidney, lungs, brain) (P <.05); compared with sham immunized controls. Vaccination with rSap2 cloned from C. albicans did not improve survival in non-albicans C. tropicalis infection, despite the protein having ∼60% homology across species. Mice vaccinated with rSap2-parapsilosis also exhibited significantly higher levels of IFN gamma, IL-17, and IL-4 cytokine levels just before infection, which correlated with protection. In addition, rSap2-parapsilosis vaccination induced high titers of Sap2-specific antibodies, and a fraction of antibodies could bind whole fungus (which were predominantly of IgM isotype). Notably, sera from rSap2-parapsilosis vaccinated mice exhibited increased C. tropicalis biofilm inhibition ability and enhanced neutrophil-mediated fungal killing in vitro. Sap2-specificity was further confirmed by depleting antigen-specific antibodies. Passive transfer of Sap2-parapsilosis immune serum significantly reduced fungal burdens in naive mice, as compared to mice receiving sham-immune serum, upon infection. Higher numbers of total CD19 + B-cells, plasma cells, and Candida-binding B-cells in rSap2-parapsilosis vaccinated mice indicate a role of B-cells during early stages of Sap2-mediated immune response. Epitope analysis performed using identified B-cell epitopes provides insights about including important IgM and IgG epitopes, when designing multivalent or multi-epitope anti-Candida vaccine/s.

Conclusion

Mice immunized with recombinant Sap2 cloned from C. parapsilosis exhibited increased survival during C. tropicalis mediated systemic candidiasis. Both Th1/Th17 mediated cellular immunity and humoral immunity contribute toward protection. Our results establish a role of B-cells and antibodies in generation of protective immune responses against Sap2 vaccine antigen during non-albicans Candida mediated murine systemic candidiasis.

Synthesis of vildagliptin loaded acrylamide-g-psyllium/alginate-based core-shell nanoparticles for diabetes treatment

Diabetes mellitus has become a major public health concern all over the world. Vildagliptin is one of the antidiabeticdrug that can overcome the existing problem of this prevalent disease. Present study aims to synthesize and investigate the role of vildagliptin-loaded core-shell nanoparticle of grafted psyllium and alginate (VG@P/A-NPs) in anti-diabetes application. FTIR, SEM, XRD, ¹³CNMR and zeta analyzer were used for characterization of the core-shell nanoparticles (VG@P/A-NPs). The synthesized acrylamide-grafted-psyllium was also optimized through varying grafting parameters such as acrylamide and ceric ammonium nitrate (CAN) concentration, time and temperature to obtain the maximum yield of acrylamide-grafted-psyllium. Rheological analysis of pure psyllium, grafted psyllium and alginate were also performed. For biological studies, the first cytotoxicity of grafted psyllium and VG@P/A-NPs were examined on human lung adenocarcinoma cell line A549 in which it was observed that VG@P/A-NPs did not exhibited any toxicity. The antidiabetic potential of VG@P/A-NPs was investigated by glucose uptake assay, using TNF-α induced insulin resistance skeletal cell model using mouse muscle L6 cell line. The insulin signaling impaired cell line displayed a highly significant (p < 0.0001) dose-dependent increase in glucose uptake after treatment with increasing doses of VG@P/A-NPs.The drug release behavior of VG@P/A-NPs was examined at various pH and the highest drug release (98 %) was obtained at pH (7.4). The drug release kinetic data was following the Higuchi (R² = 0.9848) kinetic model, suggesting the release of drug from vildagliptin-loaded grafted psyllium-alginate core-shell nanoparticles (VG@P/A-NPs) as a square root of time-dependent process and diffusion controlled. This study provides an economical and environment-friendly approach towards the synthesis of VG@P/A-NPs with antidiabetes applications.

Expression, Purification, and Refolding of Chikungunya Virus Full-Length Envelope E2 Protein along with B-Cell and T-Cell Epitope Analyses Using Immuno-Informatics Approaches

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus, which causes severe illness in humans and is responsible for epidemic outbreaks in Africa, Asia, North and South America, and Europe. Despite its increased global prevalence, no licensed vaccines are available to date for treating or preventing CHIKV infection. The envelope E2 protein is one of the promising subunit vaccine candidates against CHIKV. In this study, we describe successful cloning, expression, and purification of CHIKV E2 full-length (E2-FL) and truncated (E2-ΔC and E2-ΔNC) proteins in the Escherichia coli expression system. The recombinant E2 proteins were purified from inclusion bodies using Ni-NTA chromatography. Further, we describe a detailed refolding procedure for obtaining the CHIKV E2-FL protein in native conformation, which was confirmed using circular dichroism and Fourier transform infrared spectroscopy. BALB/c mice immunized with the three different E2 proteins exhibited increased E2-specific antibody titers compared to sham-immunized controls, suggesting induction of strong humoral immune response. On analyzing the E2-specific antibody response generated in immunized mice, the CHIKV E2-FL protein was observed to be the most immunogenic among the three different CHIKV E2 antigens used in the study. Our B-cell and T-cell epitope mapping results indicate that the presence of specific immunogenic peptides located in the N-terminal and C-terminal regions of the CHIKV E2-FL protein may contribute to its increased immunogenicity, compared to truncated CHIKV E2 proteins. In summary, our study provides a detailed protocol for expressing, purifying, and refolding of the CHIKV E2-FL protein and provides an understanding of its immunogenic epitopes, which can be exploited for the development of novel multiepitope-based anti-CHIKV vaccine strategies.

Spinal Vascular Shunts: A Patterned Approach

Spinal vascular shunts, including fistulas and malformations, are rare and complex vascular lesions for which multiple classification schemes have been proposed. The most widely adopted scheme consists of 4 types: type I, dural AVFs; type II, intramedullary glomus AVMs; type III, juvenile/metameric AVMs; and type IV, intradural perimedullary AVFs. MR imaging and angiography techniques permit detailed assessment of spinal arteriovenous shunts, though DSA is the criterion standard for delineating vascular anatomy and treatment planning. Diagnosis is almost exclusively based on imaging, and features often mimic more common pathologies. The radiologist's recognition of spinal vascular shunts may improve outcomes because patients may benefit from early intervention.

Expression and Purification along with Evaluation of Serological Response and Diagnostic Potential of Recombinant Sap2 Protein from C. parapsilosis for Use in Systemic Candidiasis

Systemic candidiasis is the fourth most common bloodstream infection in ICU patients worldwide. Although C. albicans is a predominant species causing systemic candidiasis, infections caused by non-albicans Candida (NAC) species are increasingly becoming more prevalent globally along with the emergence of drug resistance. The diagnosis of systemic candidiasis is difficult due to the absence of significant clinical symptoms in patients. We investigated the diagnostic potential of recombinant secreted aspartyl proteinase 2 (rSap2) from C. parapsilosis for the detection of Candida infection. The rSap2 protein was successfully cloned, expressed and purified using Ni-NTA chromatography under denaturing conditions using an E. coli-based prokaryotic expression system, and refolded using a multi-step dialysis procedure. Structural analysis by CD and FTIR spectroscopy revealed the refolded protein to be in its near native conformation. Immunogenicity analysis demonstrated the rSap2 protein to be highly immunogenic as evident from significantly high titers of Sap2-specific antibodies in antigen immunized Balb/c mice, compared to sham-immunized controls. The diagnostic potential of rSap2 protein was evaluated using immunoblotting and ELISA assays using proven candidiasis patient serum and controls. Immunoblotting results indicate that reactivity to rSap2 was specific to candidiasis patient sera with no cross reactivity observed in healthy controls. Increased levels of anti-Sap2-specific Ig, IgG and IgM antibodies were observed in candidiasis patients compared to controls and was similar in sensitivity obtained when whole Candida was used as coating antigen. In summary, the rSap2 protein from C. parapsilosis has the potential to be used in the diagnosis of systemic candidiasis, providing a rapid, convenient, accurate and cost-effective strategy.

Synthesis of rifaximin loaded chitosan-alginate core-shell nanoparticles (Rif@CS/Alg-NPs) for antibacterial applications

The present work aims to synthesize the rifaximin loaded chitosan-alginate core-shell nanoparticles (Rif@CS/Alg-NPs) for antibacterial applications. The core-shell nanoparticles (Rif@CS/Alg-NPs) were characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-rays diffraction (XRD) and zeta analyzer. The antibacterial activities of Rif@CS/Alg-NPs were investigated against three species of bacteria namely Escherichia coli (E. coli), Pseudomonas aeruginosa (PA) and Bacillus haynesii (BH). Rif@CS/Alg-NPs exhibited outstanding antibacterial activities against E. coli, P. aeroginosa and Bacillus haynesii (BH) with 24 mm, 30 mm and 34 mm zone of inhibitions, respectively. Cytotoxicity of Rif@CS/Alg-NPs was also evaluated against human lung adenocarcinoma cell line A549 and found to be nontoxic. The drug release behavior of Rif@CS/Alg-NPs was investigated at different pH levels and maximum drug release (80%) was achieved at pH (7.2). The drug release kinetic data followed the Higuchi (R² = 0.9963) kinetic model, indicating the drug release from Rif@CS/Alg-NPs as a square root of time-dependent process and diffusion controlled. Current research provides a cost-effective and green approach toward the synthesis of Rif@CS/Alg-NPs for its antibacterial applications.

A role of B-cells and antibodies in generation of protective immune responses against a vaccinating antigen during non-albicans Candida mediated systemic candidiasis

While cellular immunity is acknowledged to be critical for vaccine-mediated protection during systemic candidiasis, the role of humoral immunity is not clear. We investigated the role of B cells and antibodies in conferring protective advantage during Candida tropicalis mediated murine systemic candidiasis, using a lead vaccine candidate, Sap2 (secreted aspartyl proteinase 2) obtained from C. parapsilosis. Compared to sham-immunized mice, Sap2-parapsilosis vaccinated mice exhibited significantly improved survival outcomes (p=0.02) and reduced organ fungal burdens (p&lt;0.05). Sap2-parapsilosis vaccination induced high titres of Sap2-specific antibodies, and a fraction of antibodies could bind whole fungus (of predominantly IgM isotype). Notably, sera from Sap2-parapsilosis-vaccinated mice exhibited increased C. tropicalis biofilm inhibition ability and enhanced neutrophil-mediated fungal killing in vitro. Sap2-specificity was further confirmed by depleting antigen-specific antibodies. Passive transfer of Sap2-parapsilosis immune serum significantly reduced fungal burdens in naive mice, as compared to mice receiving sham-immune serum, upon infection. Higher numbers of total CD19+ B cells, plasma cells and Candida-binding B cells in Sap2-vaccinated mice indicate towards a role of B cells during early stages of Sap2-mediated immune response. Epitope analysis performed using identified B cell epitopes provides insights about including important IgM and IgG epitopes, when designing multivalent or multiepitope anti-Candida vaccine/s. In summary, our results establishes a role of B cells and antibodies in contributing towards protective efficacy of Sap2 vaccine antigen during murine systemic candidiasis.

Protective role of secreted aspartyl proteinase in murine systemic candidiasis caused by non-albicans Candida species

Non-albicans Candida species are increasingly becoming more prevalent globally and emergence of drug resistance is another cause of concern. We investigated the protective potential of secreted aspartyl proteinase (Sap2), a leading candidate vaccine antigen identified from research based on C. albicans, in murine systemic candidiasis caused by non-albicans Candida species. The Sap2 genes were successfully cloned and expressed as recombinant proteins from C. albicans, C. tropicalis and C. parapsilosis. Groups of Balb/c mice were immunized with individual rSap2 protein along with alum as adjuvant, followed by systemic infection with lethal dose of C. tropicalis. The protective potential of each rSap2 protein was evaluated using survival analysis and estimation of organ fungal burden. Mice immunized with rSap2 cloned from C. parapsilosis showed highest increase in survival time (p=0.02) and maximum reduction in organ fungal burden (spleen, kidneys, lungs, brain) (p&lt;0.05); compared to sham immunized controls. Immunization with rSap2 cloned from C. albicans did not improve survival in non-albicans C. tropicalis infection, despite the protein having ~60% homology across species. Mice immunized with rSap2 cloned from C. parapsilosis also exhibited significantly higher levels of IFN gamma and IL-4 cytokine levels just before infection, which correlated with protection. The anti-Sap2 specific antibody titres were measured. No correlation was observed between level of Sap2-specific IgG titres and survival outcome. The IgG response was primarily Th2, belonging to IgG1 subtype. Further cellular and histological studies are in progress to characterize the murine rSap2-parapsilosis specific protective immune response in detail.

Antibody and B Cell Subset Perturbations in Human Immunodeficiency Virus-Uninfected Patients With Cryptococcosis

The importance of antibody immunity in protection against Cryptococcus neoformans remains unresolved. We measured serum C neoformans-specific and total antibody levels and peripheral blood B cell subsets of 12 previously healthy patients with cryptococcosis (cases) and 21 controls. Before and after adjustment for age, sex, and race, cryptococcal capsular polysaccharide immunoglobulin G was higher in cases than controls, whereas total B and memory B cell levels were lower. These associations parallel previous findings in patients with human immunodeficiency virus-associated cryptococcosis and suggest that B cell subset perturbations may also associate with disease in previously normal individuals with cryptococcosis.

Naïve B cells reduce fungal dissemination in Cryptococcus neoformans infected Rag1-/- mice

IgM and B-1 cell deficient mice exhibit early C. neoformans dissemination from lungs to brain, but a definitive role for B cells in conferring resistance to C. neoformans dissemination has not been established. To address this question, we developed an intranasal (i.n.) C. neoformans infection model in B and T cell deficient Rag1^-/- mice and found they also exhibit earlier fungal dissemination and higher brain CFU than wild-type C57Bl/6 (wild-type) mice. To probe the effect of B cells on fungal dissemination, Rag1^-/- mice were given splenic (intravenously) or peritoneal (intraperitoneally) B cells from wild-type mice and infected i.n. with C. neoformans 7 d later. Mice that received B cells had lung histopathology resembling wild type mice 14 d post-infection, and B-1, not B-2 or T cells in their lungs, and serum and lung IgM and IgG 21 d post-infection. Lung CFU were comparable in wild-type, Rag1^-/-, and Rag1^-/- mice that received B cells 21 d post-infection, but brain CFU were significantly lower in mice that received B cells than Rag1^-/- mice that did not. To determine if natural antibody can promote immunity in our model, we measured alveolar macrophage phagocytosis of C. neoformans in Rag1^-/- mice treated with naive wild-type IgM-sufficient or sIgM^-/- IgM-deficient sera before infection. Compared to IgM-deficient sera, IgM-sufficient sera significantly increased phagocytosis. Our data establish B cells are able to reduce early C. neoformans dissemination in mice and suggest natural IgM may be a key mediator of early antifungal immunity in the lungs.

Eculizumab for atypical hemolytic-uremic syndrome in India: First report from India and the challenges faced

Much progress has been made in understanding the pathophysiology and treatment of atypical hemolytic uremic syndrome (aHUS). Plasma therapy is the mainstay of treatment for aHUS. The availability of the first effective anti-complement therapeutic agent, eculizumab, has dramatically changed the outlook of this disease. However, its use in clinical practice raises important questions, such as who should receive the drug, when to start such therapy, and is it safe to stop treatment once the disease is controlled. We describe here for the 1^st time in India, use of eculizumab in a 12-year-old boy with aHUS. We also describe in this report challenges faced in procuring the drug, and an ideal, evidence-based method of treating aHUS in children.

Host immunity to Cryptococcus neoformans

Cryptococcosis is caused by the fungal genus Cryptococcus. Cryptococcosis, predominantly meningoencephalitis, emerged with the HIV pandemic, primarily afflicting HIV-infected patients with profound T-cell deficiency. Where in use, combination antiretroviral therapy has markedly reduced the incidence of and risk for disease, but cryptococcosis continues to afflict those without access to therapy, particularly in sub-Saharan Africa and Asia. However, cryptococcosis also occurs in solid organ transplant recipients and patients with other immunodeficiencies as well as those with no known immunodeficiency. This article reviews innate and adaptive immune responses to C. neoformans, with an emphasis on recent studies on the role of B cells, natural IgM and Fc gamma receptor polymorphisms in resistance to cryptococcosis.

Molecular characterization of the early B cell response to pulmonary Cryptococcus neoformans infection

The role of B cells in host defense against fungi has been difficult to establish. We quantified and determined the molecular derivation of B-1a, B-1b, and B-2 B cell populations in C57BL/6 mice after pulmonary infection with Cryptococcus neoformans. Total B-1 and B-2 cell numbers increased in lungs and peritoneal cavity as early as day 1 postinfection, but lacked signs of clonal expansion. Labeled capsular (24067) and acapsular (Cap67) C. neoformans strains were used to identify C. neoformans-binding B cell subsets by flow cytometry. Peritoneal cavity B-1a B cells exhibited the most acapsular and capsular C. neoformans binding in C. neoformans-infected mice, and C. neoformans-selected B-1 B cells secreted laminarin- and C. neoformans-binding IgM. Single-cell PCR-based sequence analysis of B-1a, B-1b, and B-2 cell IgH V region H chain (V(H)) genes revealed increased usage of V(H)11 and V(H)12, respectively, in acapsular and capsular C. neoformans-selected B-1a cells. Germline V(H) segments were used, with capsular C. neoformans-selected cells having less junctional diversity than acapsular C. neoformans-selected cells. Further studies in B-1 B cell-depleted mice showed that these mice had higher brain and lung fungal burdens and less alveolar macrophage phagocytosis of C. neoformans than did control and B-1a B cell-reconstituted mice. Taken together, these results establish a mechanistic role for B-1 B cells in the innate B cell response to pulmonary infection with C. neoformans and reveal that IgM-producing B-1a cells, which express germline V(H) genes, bind C. neoformans and contribute to early fungal clearance. Thus, B-1a B cells provide a first line of defense during pulmonary C. neoformans infection in mice.

Molecular characterization of antigen-specific B1 and B2 B-cells populations in Cryptococcus neoformans infection in mice (43.1)

We examined B1 and B2 B-cell repertoires in Cryptococcus neoformans infection in mice. Flow-cytometry based antigen-specific staining for B-cell populations generated in response to pulmonary infection was performed using labeled un-encapsulated and encapsulated C. neoformans strains. FACS sorting and single-cell nested PCR was employed to characterize the IgH repertoire. An increase in total peritoneal B1a, B1b and B2 cell numbers was observed as early as day 3 post-infection. Frequencies of both acapsular and capsular antigen-specific cells were increased in the B1a subpopulation (18%, 5%) in infected compared to naïve mice (11%, 2%). The heavy chains of antigen-specific B2 and B1b cells recognizing acapsular and capsular cryptococcus belonged predominantly to the VH1 family. Interestingly, increased VH11 (22%) and VH12 (33%) usage was observed in antigen-specific B1a cells recognizing acapsular and encapsulated cryptococcus, respectively, compared to the conventional B1a population. Although all acapsular (VH11+) and capsular (VH12+) B1a cells used the same VH11.2.53 and VH12.1.78 genes, 60% and 80% rearrangements were unique, respectively. VH genes in both cases were essentially germline, however 40% of acapsular specific B1a cells had 4 or more N-nucleotide additions compared to capsular specific B1a cells (20%). These results indicate that naturally occurring phosphatidyl choline reactive B1a cells have broad specificities and can bind to encapsulated cryptococcus.

A study on clinical attachment loss and gingival inflammation as etiologic factors in pathologic tooth migration

BACKGROUND

Several etiologic factors have been listed for pathologic migration of periodontally involved teeth based mainly on clinical observations with scarce scientific evidence. Present study was carried out to find out relationship of clinical attachment loss and gingival inflammation with pathologic tooth migration.

MATERIALS AND METHODS

A total of 37 patients having 50 pairs of migrated and non-migrated contralateral teeth were taken into consideration.

RESULTS

Mean total attachment loss per tooth in migrated and non migrated tooth is 13.32 ± 0.74 S.E. and 8.34 ± 0.58 S.E., respectively (P < 0.001), which reveals a positive correlation. There seems to be an association between frequency of migration and severity of attachment loss since highest percentage of migrations were seen in maximum total attachment loss group. Relationship could not be established between severity of attachment loss and severity of migration for which more data may be required. Also, it was seen that gingival index was significantly higher in migrated group.

CONCLUSION

Findings suggest that there exists a direct relationship between pathologic migration and clinical attachment loss as well as gingival inflammation.

CLINICAL RELEVANCE

Results emphasize the importance of early treatment of periodontitis to curb inflammation, which seems to be more important since it is completely reversible, and attachment loss also in order to prevent unaesthetic complications. Moreover bleeding along with recent change in position of teeth should be considered as important sign of active, moderate to severe periodontal disease by general dentists and hygienists so that they can refer for specialist consultation.

Population based study to assess prevalence and risk factors of gastroesophageal reflux disease in a high altitude area

AIM

We did a population-based cross-sectional study to investigate the prevalence and risk factors of gastroesophageal reflux disease (GERD) in a high altitude area.

METHODS

An observational study using a validated questionnaire consisting of demographic, lifestyle and dietary characteristics was administered in an interview based format by two clinicians on a sample of adult population residing in urban area and rural high altitude areas of Ladakh. Presence of GERD was defined as a score of ≥4 using a previously validated symptom score based on the severity and frequency of heartburn and regurgitation. Other factors studied were body mass index (BMI), oxygen saturation levels by pulse oximetry and serum lipid profile. A multivariate analysis was done to find out risk factors for symptomatic GERD.

RESULTS

Of the 905 subjects analyzed, there were 399 (44.1%) men; 469 (51.8%) were from rural background and 722 (79.8%) lived in areas 3,000 m above sea level. Symptomatic GERD was present in 169 (18.7%) subjects. Regurgitation occurred once a week in 34.8% and heartburn occurred in 42.9% of subjects. Sixteen (9.5%) had moderate-severe disease activity while 153 (90.5%) had mild disease. Three hundred and eighty-eight (42.7%) and 315 (34.8%) subjects had symptom of heartburn and regurgitation (at least once a week), respectively. On multivariate analysis, risk factors for GERD were age ≤50 years (OR: 1.508, 95% CI: 1.028-2.213), sedentary lifestyle (OR: 2.78, 95% CI: 1.016-7.638), lower intake of salt tea (OR: 1.663, 95% CI: 1.014-2.726); whereas the protective factors were no intake of meat (OR: 0.841, 95% CI: 0.715-0.990), intake of fresh fruits ≥1/week (OR: 0.631, 95% CI: 0.409-0.973), and serum LDL ≤150 mg/dL (OR: 0.435, 95% CI: 0.218-0.868).

CONCLUSION

This population-based study in a high altitude area in India suggests a high prevalence (18.7%) of GERD. A younger age group, sedentary lifestyle, serum LDL >150 mg/dL, high consumption of meat, low consumption of salted tea and low consumption of fresh fruits were significant risk factors for development of GERD.

The Pharmacognosy of Rauwolfia

Rauwolfia of Indian commerce consists of the dried rhizomes and roots, with occasional small pieces of attached aerial stem, of Rauwolfia serpentina Benth. The important histological features are the cork, composed of alternating layers of broad and narrow cells, giving a somewhat spongy and friable exterior to the drug; the narrow bark and the wide central mass of wood in the root or broad ring in the rhizome, showing about 3 to 8 growth rings; a tetrarch, or occasionally triarch, primary xylem in roots or a very small pith at the centre of rhizomes; in the periphery of the pith a ring of about 20 small groups of perimedullary phloem. All the cells of the wood, including those of the medullary rays are lignified. The xylem vessels, fibres and parenchyma form narrow undulating radially arranged bands, separated by large medullary rays in the root and by smaller ones in the rhizome. The vessel segments are small and narrow and the xylem fibres are often irregularly shaped with long, usually much contorted, tapering ends; many of the vessels, especially in the rhizome, show tylosis and occasionally contain resinous masses. The phloem also occurs in undulating bands similar to those of the xylem; phloem fibres are absent. In the rhizome, unlignified pericyclic fibres occur, either singly or in groups of 2 to 4; they show the local and sub-terminal elongated-oval enlargements characteristic of the Apocynaceæ. All the parenchymatous tissues, except the cork, contain numerous starch grains, about 4 to 20 to 50μ in diameter. Cells containing a brownish yellow secretion occur in small numbers, either singly or in short longitudinal rows, in the bark, wood and pith, being most frequent in the cortex of pieces of rhizome. Typical laticiferous tubes are absent. Calcium oxalate occurs in numerous cells of the phloem and of the medullary rays of the bark; the crystals are either well-formed prisms or aggregates of irregular angular components.

Eliminating expression of erucic acid-encoding loci allows the identification of "hidden" QTL contributing to oil quality fractions and oil content in Brassica juncea (Indian mustard)

Oil content and oil quality fractions (viz., oleic, linoleic and linolenic acid) are strongly influenced by the erucic acid pathway in oilseed Brassicas. Low levels of erucic acid in seed oil increases oleic acid content to nutritionally desirable levels, but also increases the linoleic and linolenic acid fractions and reduces oil content in Indian mustard (Brassica juncea). Analysis of phenotypic variability for oil quality fractions among a high-erucic Indian variety (Varuna), a low-erucic east-European variety (Heera) and a zero-erucic Indian variety (ZE-Varuna) developed by backcross breeding in this study indicated that lower levels of linoleic and linolenic acid in Varuna are due to substrate limitation caused by an active erucic acid pathway and not due to weaker alleles or enzyme limitation. To identify compensatory loci that could be used to increase oil content and maintain desirable levels of oil quality fractions under zero-erucic conditions, we performed Quantitative Trait Loci (QTL) mapping for the above traits on two independent F1 doubled haploid (F1DH) mapping populations developed from a cross between Varuna and Heera. One of the populations comprised plants segregating for erucic acid content (SE) and was used earlier for construction of a linkage map and QTL mapping of several yield-influencing traits in B. juncea. The second population consisted of zero-erucic acid individuals (ZE) for which, an Amplified Fragment Length Polymorphism (AFLP)-based framework linkage map was constructed in the present study. By QTL mapping for oil quality fractions and oil content in the ZE population, we detected novel loci contributing to the above traits. These loci did not co-localize with mapped locations of the fatty acid desaturase 2 (FAD2), fatty acid desaturase 3 (FAD3) or fatty acid elongase (FAE) genes unlike those of the SE population wherein major QTL were found to coincide with mapped locations of the FAE genes. Some of the new loci identified in the ZE population could be detected as 'weak' contributors (with LOD < 2.5) in the SE population in which their contribution to the traits was "masked" due to pleiotropic effects of erucic acid genes. The novel loci identified in this study could now be used to improve oil quality parameters and oil content in B. juncea under zero-erucic conditions.

Antiphospholipid antibodies in young Indian patients with stroke

BACKGROUND

Stroke may be caused by antiphospholipid antibodies (APL), especially in young persons without other risk factors.

AIM

The aim of this study was to determine the prevalence of two clinically significant APL-anticardiolipin antibody (ACL) and lupus anticoagulants (LA) in young patients presenting with sudden neurological deficit.

SETTINGS AND DESIGN

A case-control study performed in a large tertiary care government hospital.

MATERIALS AND METHODS

Ten milliliters of blood was collected from 51 consecutive young patients (age less than 45 years) diagnosed as ischemic stroke and 50 healthy age- and sex-matched controls.

STATISTICAL ANALYSIS

Statistical analysis was done using Epi Info (TM) 6 software.

RESULTS

Overall, the risk factor profile was: Smoking (23.5%), positive family history (13.7%), hyperlipidemia (8%), and diabetes mellitus (3.6%). APL (LA and ACL) were present in 29.4% of the samples and in 4% of controls. The 'P' value for ACL and LA was 0.03 and 0.02 respectively, but the maximum level of ACL was 25 GPL units only. One-fourth of the patients were smokers and one-sixth had a family history of thrombosis ( P = 0.048 and 0.036, respectively).

CONCLUSIONS

APL, positive family history and smoking were significantly associated with stroke in the young. We advocate screening for APL in all young patients with stroke.

Early Cognitive Impairment: Role of Clock Drawing Test

BACKGROUND

Folstein's Mini Mental Status Examination (MMSE) often fails to identify executive dysfunction even if quite severe. Detailed neuropsychological tests and extensive bedside tests are available to evaluate executive function, but most of them are time consuming. This study was done to determine the value of a Clock Drawing Test (CDT) as a simple tool to identify cognitive dysfunction in various neurological disorders and to assess its utility as an adjunct to MMSE in identifying executive dysfunction in a a busy out patient department (OPD).

METHODS

A total of 81 patients suffering from neurological disorders and 81 controls were studied. All subjects received the MMSE and the CDT. The CDT is divided into an unprompted task that is sensitive to executive control (CDT 1) and a copying task which is not (CDT 2).

RESULT

All the three tests (CDT 1, CDT 2 and MMSE) could recognize cognitive and executive function deficits, when compared with age and sex matched controls (p < 0. 001). CDT scores correlated strongly with the level of executive function deficits. CDT+MMSE detected 95% cases as abnormal as compared to 47% detected by MMSE alone.

CONCLUSION

CDT along with MMSE can detect executive control deficits and cognitive deficits. The CDT 1 tests executive control performance, while CDT 2 tests posterior cortical deficits.

Systematic design and testing of nested (RT-)PCR primers for specific amplification of mouse rearranged/expressed immunoglobulin variable region genes from small number of B cells

The aim of this study was to develop a highly specific and sensitive (RT-)PCR capable of potentially amplifying the rearranged/expressed VH and VL gene belonging to any mouse immunoglobulin V gene family from a single or a small number of B cells. A database of germline immunoglobulin sequences was used to design 112 primers for a nested (RT-)PCR based strategy to cover all VH, VL, JH, JL, CH and CL gene families/genes from C57BL/6 and BALB/c mice. 93.7% of the primers had 4-fold or less, while 71.4% had no degeneracy. The proportions of germline V genes to which the primers bind with no, up to 1 and up to 2 mismatches are 59.7%, 84.1% and 94.9%, respectively. Most but not all V gene family specific primers designed allow amplification of full-length V genes. The nested primers permit PCR amplification of rearranged V genes belonging to all VH and VL gene families from splenocyte genomic DNA. The V gene family-specific nature of the primers was experimentally confirmed for randomly selected 6 VH and 6 Vkappa families, and all Vlambda genes. The broad V gene family coverage of our primer set was experimentally validated by amplifying the rearranged/expressed VH and VL genes from splenocytes and a panel of 38 hybridomas under conditions where primer mixes and genomic DNA or total RNA was used as starting template. We observed no or low-level cross-family priming. Pooled constant region specific primers allowed efficient RT-PCR amplification of H and L chain isotypes. The expressed VH and VL genes belonging to different V gene families RT-PCR amplified from a mixture of hybridomas in a representative manner. We successfully amplified the expressed VH and Vkappa gene from a single hybridoma cell by RT-PCR and from 10-15 microdissected B cells by genomic PCR. This, first of its kind, comprehensive set of highly sensitive and specific nested primers that provide broad V gene family coverage will open up new avenues and opportunities to study various aspects of mouse B cell biology.

Prevalence of duodenal ulcer-promoting gene (dupA) of Helicobacter pylori in patients with duodenal ulcer in North Indian population

BACKGROUND

The duodenal ulcer (DU)-promoting gene (dupA) of Helicobacter pylori has been identified as a novel virulent marker associated with an increased risk for DU. The presence or absence of dupA gene of H. pylori present in patients with DU and functional dyspepsia in North Indian population was studied by polymerase chain reaction (PCR) and hybridization analysis.

MATERIALS AND METHODS

One hundred and sixty-six patients (96 DU and 70 functional dyspepsia) were included in this study. In addition, sequence diversity of dupA gene of H. pylori found in these patients was analyzed by sequencing the PCR products jhp0917 and jhp0918 on both strands with appropriate primers.

RESULTS

PCR and hybridization analyses indicated that dupA gene was present in 37.5% (36/96) of H. pylori strains isolated from DU patients and 22.86% (16/70) of functional dyspepsia patients (p < or = .05). Of these, 35 patients with DU (97.2%) and 14 patients with functional dyspepsia (81.25%) were infected by H. pylori positive for cagA genotype. Furthermore, the presence of dupA was significantly associated with the cagA-positive genotype (p < or = .02).

CONCLUSION

Results of our study have shown that significant association of dupA gene with DU in this population. The dupA gene can be considered as a novel virulent marker for DU in this population.

Effect of resin type and manufacturing method on wear of polyethylene tibial components

The purpose of this study was to examine the effect of ultrahigh molecular weight polyethylene resin type and manufacturing method on wear of Miller-Galante I and II tibial knee components. Thirteen Miller-Galante I and 10 Miller-Galante II components were retrieved at revision surgery. The Miller-Galante I tibial components were made by direct compression molding of Hi-fax 1900 resin and the Miller-Galante II tibial components were made by machining from ram extruded rod of GUR 415 resin. Both generations were gamma radiation sterilized in air. The Miller-Galante I retrievals had significantly more wear damage in the form of scratching and embedded metallic debris, whereas the Miller-Galante II retrievals had significantly more wear damage in the form of delamination. For the implants with an implantation time of 5 years or more, the Miller-Galante II polyethylene had a significantly greater maximum density value than did the Miller-Galante I polyethylene. Examination of thin sections of the Miller-Galante II components revealed that delamination occurred through a subsurface region of severely oxidatively degraded polyethylene; no such subsurface degraded region was observed for the Miller-Galante I components. The results of this study suggest that delamination of polyethylene tibial components that have been gamma radiation sterilized (in air) is influenced by resin type or manufacturing method or both.

Induction of neurally mediated syncope with adenosine

BACKGROUND

Tilt testing is used to establish the diagnosis of neurally mediated syncope. However, applicability of the tilt test is limited by test sensitivity and length of time required to perform the test. We hypothesized that adenosine could facilitate the induction of neurally mediated syncope through its sympathomimetic effects and therefore could be used as an alternative to routine tilt testing.

METHODS AND RESULTS

In protocol 1, the yield of adenosine tilt testing (12 mg while upright, followed by 60 degrees tilt for 5 minutes) and a 15-minute isoproterenol tilt test were compared in 84 patients with a negative 30-minute drug-free tilt test. In protocol 2, 100 patients underwent an initial adenosine tilt test followed by our routine tilt test (30-minute drug-free tilt followed by a 15-minute isoproterenol tilt). Six additional control patients underwent microneurography of the peroneal nerve to compare the sympathomimetic effects during bolus administration of adenosine and continuous infusion of isoproterenol. In protocol 1, the yields of adenosine (8 of 84, 10%) and isoproterenol (7 of 84, 8%) tilt testing were comparable (P=NS). In protocol 2, the yields of adenosine (19 of 100, 19%) and routine (22 of 100, 22%) tilt testing were also comparable (P=NS). Although the yield of adenosine tilt testing was comparable in both protocols, patients with a negative adenosine tilt test but a positive routine tilt test usually required isoproterenol to elicit the positive response. Microneurography confirmed discordant sympathetic activation after adenosine and isoproterenol administration.

CONCLUSIONS

Adenosine is effective for the induction of neurally mediated syncope, with a diagnostic yield comparable to routine tilt testing. However, the discordant results obtained with adenosine and the isoproterenol phase of routine tilt testing suggest that adenosine and isoproterenol tilt testing may have complementary roles in eliciting a positive response. Therefore, a tilt protocol that uses an initial adenosine tilt followed, if necessary, by an isoproterenol tilt would be expected to increase the overall yield and reduce the duration of tilt testing.

A controlled trial of choleretic and hepatoprotective actions of Livzon and dehydrocholic acid in a model of obstructive jaundice in albino rats

The authors have tried to examine the hepatoprotective and cholerectic action of a new indigenised drug, Livzon (Hind Chemicals Ltd., Kanpur, India) and compared its action to Decholin (casella-Riedel Pharma GmbH, Frankfurt, Germany), a known hepatoprotective and choleretic agent. Albino rats were chosen as the experimental animals. Obstructive jaundice was created by ligating the common bile ducts after taking liver biopsies. The animals were divided into three groups: (i) Control group-no drug was given, (ii) Livzon trial group, (iii) Decholin group. The animals were reoperated, liver biopsies were taken and histologically examined. The study confirmed the hepatoprotective and choleretic actions of Livzon and Decholin. However, Decholin was more of a choleretic, the Livzon was more hepatoprotective.

Field trial of an electrically passive optical-fiber magnetometer

A field trial of an electrically passive optical-fiber magnetometer incorporated into the transient electromagnetic method of geomagnetic surveying is described. The transducer of the magnetometer consisted of metallic glass wire cocoated with a length of optical fiber. The magnetometer was capable of measuring the decay rate of the surface magnetic field produced by the surveying technique. The sensor's minimum detectable field was 2.5 × 10(-8) G/√Hz at 2 kHz.