Redefining Lobe-Wise Ground-Glass Opacity in COVID-19 Through Deep Learning and its Correlation With Biochemical Parameters.

During COVID-19 pandemic qRT-PCR, CT scans and biochemical parameters were studied to understand the patients' physiological changes and disease progression. There is a lack of clear understanding of the correlation of lung inflammation with biochemical parameters available. Among the 1136 patients studied, C-reactive-protein (CRP) is the most critical parameter for classifying symptomatic and asymptomatic groups. Elevated CRP is corroborated with increased D-dimer, Gamma-glutamyl-transferase (GGT), and urea levels in COVID-19 patients. To overcome the limitations of manual chest CT scoring system, we segmented the lungs and detected ground-glass-opacity (GGO) in specific lobes from 2D CT images by 2D U-Net-based deep learning (DL) approach. Our method shows accuracy, compared to the manual method (  âˆ¼ 80%), which is subjected to the radiologist's experience. We determined a positive correlation of GGO in the right upper-middle (0.34) and lower (0.26) lobe with D-dimer. However, a modest correlation was observed with CRP, ferritin and other studied parameters. The final Dice Coefficient (or the F1 score) and Intersection-Over-Union for testing accuracy are 95.44% and 91.95%, respectively. This study can help reduce the burden and manual bias besides increasing the accuracy of GGO scoring. Further study on geographically diverse large populations may help to understand the association of the biochemical parameters and pattern of GGO in lung lobes with different SARS-CoV-2 Variants of Concern's disease pathogenesis in these populations.

The Hha-TomB toxin-antitoxin module in Salmonella enterica serovar Typhimurium limits its intracellular survival profile and regulates host immune response.

The key to bacterial virulence relies on an exquisite balance of signals between microbe and hosts. Bacterial toxin-antitoxin (TA) system is known to play a vital role in response to stress adaptation, drug resistance, biofilm formation, intracellular survival, persistence as well as pathogenesis. In the present study, we investigated the role of Hha-TomB TA system in regulating virulence of Salmonella enterica serovar Typhimurium (S. Typhimurium) in a host model system, where we showed that deletion of hha and tomB genes displayed impaired cell adhesion, invasion, and uptake. The isogenic hha and tomB mutant strain was also found to be deficient in intracellular replication in vitro, with a highly repressed Salmonella Pathogenicity Island-2 (SPI-2) genes and downregulation of Salmonella Pathogenicity Island-1 (SPI-1) genes. In addition, the Δhha and ΔtomB did not show acute colitis in C57BL/6 mice and displayed less dissemination to systemic organs followed by their cecal pathology. The TA mutants also showed reduction in serum cytokine and nitric oxide levels both in vitro and in vivo. However, the inflammation phenotype was restored on complementing strain of TA gene to its mutant strain. In silico studies depicted firm interaction of Hha-TomB complex and the regulatory proteins, namely, SsrA, SsrB, PhoP, and PhoQ. Overall, we demonstrate that this study of Hha-TomB TA system is one of the prime regulating networks essential for S. Typhimurium pathogenesis. 1. Role of Hha-TomB toxin-antitoxin (TA) system in Salmonella pathogenesis was examined. 2. The TA mutants resulted in impaired invasion and intracellular replication in vitro. 3. The TA mutants displayed alteration in SPI-1 and SPI-2 regulatory genes inside host cells. 4. Mutation in TA genes also limited systemic colonization and inflammatory response in vivo.

MRI Abnormalities of the Brain After Complex Febrile Seizures in Children.

Background Though simple febrile seizures do not cause significant and lasting neurological deficits, complex febrile seizures (CFS) can result in neurologic sequelae. Because CFS causes cortical focal injuries and other brain lesions, it needs to be evaluated. Objective The objective of this study was to evaluate the MRI brain changes in CFS, the incidence of seizures in children aged six months to five years, and their severity in relation to MRI findings of the brain. Methods In this observational study, 36 children aged six months to five years, having fever with seizure, and fulfilling the criteria of CFS were enrolled within 48 hours of the episode. Detailed clinical and neurological examinations were performed with MRI scans to find out the probable CNS lesions of CFS. Two radiologists separately evaluated all MRI brains. Results MRI lesions of the brain were found in 11 (30.56%) CFS patients. Generalized tonic-clonic seizures (GTCS) (n=31, 86.11%) were the most common type of seizure among CFS cases. Cortical focal hyperintensity (CFH) (42.1%) was the most common MRI presentation. Positive MRI findings were significantly associated with focal convulsions (n=5, 100%) as compared to GTCS cases (n=6, 19%) (p=0.001). Conclusions CFH is the most common abnormality in the MRI brain among CFS cases. CFS patients with focal seizures or prolonged seizures in 24 hours have higher abnormal neuroimaging findings. MRI should be considered a preferred investigatory tool for detecting CNS pathology in CFS cases. Follow-up studies are needed to determine the long-term outcomes of CNS lesions in children with CFS.

C-reactive protein: A promising biomarker for poor prognosis in COVID-19 infection.

BACKGROUND: The novel coronavirus disease 2019 (COVID-19) first broke out in Wuhan, China, spread over 227 countries and caused approximately 0.3 million death worldwide. Several biomolecules have been explored for possible biomarkers for prognosis outcome. Although increased C reactive protein (CRP) is associated with death due to COVID-19 infections, results from different populations remain inconsistent. For a conclusive result, the present meta-analysis was performed. METHODS: We conducted a literature search in PubMed and Scopus database for the association of CRP concentration with COVID-19 disease outcomes. A total of 16 eligible studies were enrolled in the present analysis comprising of 1896 survivors and 849 non-survivors cases. Concentrations of CRP were compared and analyzed by a meta-analysis. RESULTS: Egger's regression analysis (intercept = 0.04, P = 0.98, 95%CI = -5.48 to 5.58) and funnel plot revealed an absence of publication bias in the included studies. Due to the presence of significant heterogeneity across the studies (Q = 252.03, Pheterogeneity = 0.000, I2 = 93.65) random model was used for the analysis of the present study. The results of the meta-analysis demonstrated a significant role of CRP in COVID-19 infection outcome (Standard difference in means = 1.371, P = 0.000). CONCLUSIONS: Concentrations of CRP remained high in patients who died of COVID-19 infection and could be a promising biomarker for assessing disease lethality.

Plausible role of bacterial toxin-antitoxin system in persister cell formation and elimination.

Although, a large proportion of pathogenic bacteria gets eliminated from hosts after antibiotic treatment, a fraction of population confronts against such effects and undergoes growth arrest to form persisters. Persistence in bacteria is a dormant physiological state where cells escape the effects of antimicrobials as well as other host immune defences without any genetic mutations. The state of dormancy is achieved through various complex phenomena and it is known that a gene pair named as toxin-antitoxin (TA) acts as a key player of persister cell formation where the toxin is activated either stochastically or after an environmental insult, thereby silencing the physiological processes. However, the controversial role of TA modules in persister cell formation has also been documented with reasonable clarity. Persisters may revert back from state of quiescence and regrow when conditions become favourable for their propagation. Therefore, the elimination of dormant bacteria is crucial, and currently, research interest is highly focussed on developing several antipersister strategies that may kill persister bacteria by targeting different molecules. It is worth examining these targets to develop appropriate therapeutic interventions against bacterial infections and it is believed that earmarking TA system can be a novel approach for resuscitation of persisters. In this review, we discussed the role of TA modules in mediating persistence with highlighting on the debatable issues regarding contribution of these modules in dormant bacteria formation. Furthermore, we discussed if these modules in bacteria can be targeted for successful elimination of dormant persister cells.

Molecular insight to influential role of Hha-TomB toxin-antitoxin system for antibacterial activity of biogenic silver nanoparticles.

Emergence of silver nanoparticles (AgNPs) as a potent antibacterial agent for clinical application has raised attention towards its mode of action and needs detailed understanding of the mechanism. The current study investigates the influential role of Hha-TomB toxin-antitoxin system in determination of AgNPs antibacterial activity. AgNPs were synthesized by biogenic process using bacterial supernatant and were characterized for their physiochemical properties. Microbiological and computational assays like molecular docking, growth curve analysis, live/dead assay, oxidative stress and apoptosis assay were performed with wild type (WT) and mutants (Δhha, ΔtomB) strains treated with AgNPs for elucidation of mechanism. Stable AgNPs having size 30-40 nm and zeta potential -32 ± 09 mV were synthesized. AgNPs have shown significant antibacterial activity against S. typhimurium. Influential role of Hha-TomB TA proteins was observed in antibacterial effect by their altered expression level change in ROS level and programmed cell death. Molecular investigation elucidated the effect of AgNPs as consequence of their interaction with cellular proteins with different amino acids via hydrophobic interaction leading to alteration of cellular metabolic processes like ROS induction and apoptosis causing ultimate death. The study provided a detail illustration of Hha-TomB TA system influence on antibacterial mechanism of AgNPs for wide spectrum clinical application.

Vaccine development for enteric bacterial pathogens: Where do we stand?

Gut infections triggered by pathogenic bacteria lead to most frequently occurring diarrhea in humans accounting for million deaths annually. Currently, only a few licensed vaccines are available against these pathogens for mostly travelers moving to diarrheal endemic areas. Besides commercialized vaccines, there are many formulations that are either under clinical or pre-clinical stages of development and despite several efforts to improve safety, immunogenicity and efficacy, none of them can confer long-term protective immunity, for which repeated booster doses are always recommended. Further in many countries, financial, social and political constraints have jeopardized vaccine development program against these pathogens that enforce us to gather knowledge on safety, tolerability, immunogenicity and protective efficacy regarding the same. In this review, we analyze safety and efficacy issues of vaccines against five major gut bacteria causing enteric infections. The article also simultaneously describes several barriers for vaccine development and further discusses possible strategies to enhance immunogenicity and efficacy.

T-bet modulates the antibody response and immune protection during murine malaria.

CD4(+) T-cell subtypes govern the synthesis of different Ab isotypes and other immune functions. The influence of CD4(+) T-cell differentiation programs on isotype switching and other aspects of host immunological networks during malaria infection are currently poorly understood. Here, we used Tbx21(-/-) mice deficient for T-bet, a regulator of Th1 CD4(+) T-cell differentiation, to examine the effect of Th1 CD4(+) T cells on the immune protection to nonlethal murine malaria Plasmodium yoelii 17XNL. We found that Tbx21(-/-) mice exhibited significantly lower parasite burden that correlated with elevated levels of IgG1, indicating that T-bet-dependent Ab isotype switching may be responsible for lower parasite burden. Absence of T-bet was also associated with a transient but significant loss of T cells during the infection, suggesting that T-bet may suppress malaria-induced apoptosis or induce proliferation of T cells. However, Tbx21(-/-) mice produced greater numbers of Foxp3(+) CD25(+) regulatory CD4(+) T cells, which may contribute to the early contraction of T cells. Lastly, Tbx21(-/-) mice exhibited unimpaired production of IFN-γ by a diverse repertoire of immune cell subsets and a selective expansion of IFN-γ-producing T cells. These observations may have implications in malaria vaccine design.

The transcription factor T-bet regulates parasitemia and promotes pathogenesis during Plasmodium berghei ANKA murine malaria.

The pathogenesis of experimental cerebral malaria (ECM) is an immunologic process, mediated in part by Th1 CD4(+) T cells. However, the role of the Th1 CD4(+) T cell differentiation program on the ability to control parasitemia and susceptibility to ECM disease during blood stage malaria has never been assessed directly. Using the Plasmodium berghei ANKA murine model of ECM and mice deficient for the transcription factor T-bet (the master regulator of Th1 cells) on the susceptible C57BL/6 background, we demonstrate that although T-bet plays a role in the regulation of parasite burden, it also promotes the pathogenesis of ECM. T-bet-deficient (Tbx21(-/-)) mice had higher parasitemia than wild type controls did during the ECM phase of disease (17.7 ± 3.1% versus 10.9 ± 1.5%). In addition, although 100% (10/10) of wild type mice developed ECM by day 9 after infection, only 30% (3/10) of Tbx21(-/-) mice succumbed to disease during the cerebral phase of infection. Resistance to ECM in Tbx21(-/-) mice was associated with diminished numbers of IFN-γ-producing CD4(+) T cells in the spleen and a lower accumulation of CD4(+) and CD8(+) T cells in the brain. An augmented Th2 immune response characterized by enhanced production of activated GATA-3(+) CD4(+) T cells and elevated levels of the eotaxin, MCP-1, and G-CSF cytokines was observed in the absence of T-bet. Our results suggest that in virulent malarias, immune modulation or therapy resulting in an early shift toward a Th2 response may help to ameliorate the most severe consequences of malaria immunopathogenesis and the prospect of host survival.

Protective immunity in human filariasis: a role for parasite-specific IgA responses.

BACKGROUND: Filaria-specific antibodies of immunoglobulin (Ig) G, IgE, and IgM isotypes have been correlated with acquired immunity in the literature, but the status of filaria-specific IgA and its role in human filariasis has not been addressed. The present study attempts to fill this lacuna. METHODS: Both total and filaria-specific IgA to different developmental stages of filarial parasites were quantified by solid-phase immunoassays in 412 clinically and parasitologically defined cases occurring in an area endemic for human bancroftian filariasis in Orissa, India. RESULTS: Compared with other clinical categories, microfilariae carriers were deficient in total as well as filaria-specific IgA. More crucially, significantly high levels were observed in putatively immune control subjects from areas of endemicity. These associations were also related to sex; female subjects in each category displayed higher levels of filaria-specific IgA than did male subjects. CONCLUSION: The study demonstrates, for the first time, a positive correlation between protective immunity and increased levels of filaria-specific IgA in human bancroftian filariasis. Furthermore, filaria-specific IgA appears to be an immunological window for the sex-related differences in susceptibility to infection observed in human filariasis.