Facial Masking and SAMPPs: Potential "Variolation" in COVID-19.

Variolation is an important phenomenon in the field of immunology and has a rich historical background that has changed the perception of immunity reinforcement in human beings.1 This methodology was first used to immunize humans against smallpox infection by inoculating the infective material taken from infected patients.2 The intention was to induce a mild form of infection that would germane antibody response for tackling the future smallpox infection. To be more precise the procedure involves the application of powered smallpox scabs or fluid obtained from the pustules of the infected patients. This application is on the superficial scratches made on the skin surface of normal healthy individuals.3 Thus, the variolation is the process in which the virus is inoculated in the patient to produce an antibody response. This process produces signs and symptoms similar to the intended viral infection but usually of the milder form, possibly due to mild quantum exposure of virus particles. In the case of smallpox, this methodology was first used in China, India, and the Middle East before it was introduced into England and North America in the 1720s.4 Due to advancements done in the field of vaccination, this crude method is no longer used today. However, this process was a milestone in science that has led to the development of many vaccines available nowadays.

Novel Viewpoints on Tobacco Smoking and COVID-19.

We read with great interest an article by Karanasos et al. titled "Impact of smoking status on disease severity and mortality of hospitalized patients with COVID-19 infection: a systematic review and meta-analysis".1 It is inferred that there is an adverse impact of smoking on disease severity and mortality of hospitalized COVID-19 patients, which is more pronounced in younger patients without diabetes. Literature is flooded with papers on possible interaction and outcome of COVID-19 association with smoking. However, there are still conflicting views on the effect of smoking in patient outcomes. These conclusions are data-driven and lack valid pathogenetic background for interpretation.

Angiotensin-converting Enzyme 2 Specific Cell Subset Identification in Oral Tissues: A Need of the Hour in COVID-19 Research.

It is well known that angiotensin-converting enzyme 2 (ACE2) is an important host factor responsible for the attachment of severe acute respiratory syndrome coronavirus clad 2 (SARS-CoV-2). ACE2 has been predominantly reported to be present in lungs and nasal mucosa, which is the most common site for the initiation of COVID-19.1 Apart from lungs, ACE2 is also expressed in heart, blood vessels, kidneys, brain, intestines, etc.2 Recently various locations of the oral cavity have been found to be associated with differential expression of ACE2 protein, with the tongue being the most common site.3 Moreover, the salivary glands have also been regarded as a potential source of SARS-CoV-2 infection due to the presence of the ACE2 receptor.4 However, till date there is no strong scientific evidence that has proved the existence and interaction of ACE2 protein and spike receptor of SARS-CoV-2 on oral mucosal and salivary gland epithelial cells.

Telomerase Impinges on the Cellular Response to Oxidative Stress Through Mitochondrial ROS-Mediated Regulation of Autophagy.

Telomerase has cellular functions beyond telomere stabilization, including a role in mitochondria. The function of the catalytic component-TERT-in mitochondria is still unknown, but it seems to play a role in the response to oxidative stress. Here, we interrogated the role of the subcellular localization of TERT to the response to hydrogen peroxide (H2O2) treatment. Using normal human fibroblasts (NHF) expressing non-tagged wild type (WT) human TERT (hTERT) or nuclear localization and function (nuchTERT), a mutant that we previously described as being competent in telomere elongation, while not being able to localize to mitochondria, we found the differential activation of autophagy as a function of hTERT's subcellular localization. Specifically, we found that only cells expressing the mutant had significant increases in autophagy markers as a response to H2O2 challenge. Either the reintroduction of the mitochondrial pool of hTERT or the expression of mitochondrially-targeted catalase in mutant cells blunted the autophagic response under oxidative stress. Interestingly, autophagy activation was also associated with decreased levels of mitochondrial DNA damage. Taken together, these results suggest that the loss of hTERT in mitochondria initiates a signaling cascade that allows for cells to adapt to and cope with the lack of mitochondrial telomerase. Such effects also influence the cellular response to oxidative damage.

Dietary Modification as a Part of Prescription in Inflammatory Lesions of Oral Cavity: A Need of the Hour.

Food is an integral aspect of human life and constitutes major portion of the intake on a daily basis. The dietary patterns are highly distinctive not only for any religion but also for geographic locations. Even a particular geographic location might show vast distinctiveness in terms of consumption of food on a day-to-day basis.

Human telomerase acts as a hTR-independent reverse transcriptase in mitochondria.

Human telomerase reverse transcriptase (hTERT) is localized to mitochondria, as well as the nucleus, but details about its biology and function in the organelle remain largely unknown. Here we show, using multiple approaches, that mammalian TERT is mitochondrial, co-purifying with mitochondrial nucleoids and tRNAs. We demonstrate the canonical nuclear RNA [human telomerase RNA (hTR)] is not present in human mitochondria and not required for the mitochondrial effects of telomerase, which nevertheless rely on reverse transcriptase (RT) activity. Using RNA immunoprecipitations from whole cell and in organello, we show that hTERT binds various mitochondrial RNAs, suggesting that RT activity in the organelle is reconstituted with mitochondrial RNAs. In support of this conclusion, TERT drives first strand cDNA synthesis in vitro in the absence of hTR. Finally, we demonstrate that absence of hTERT specifically in mitochondria with maintenance of its nuclear function negatively impacts the organelle. Our data indicate that mitochondrial hTERT works as a hTR-independent reverse transcriptase, and highlight that nuclear and mitochondrial telomerases have different cellular functions. The implications of these findings to both the mitochondrial and telomerase fields are discussed.

Hemorrhagic areas as a histological prognosticator in oral cancer: A novel proposition.

Determination of prognosis in oncology practice is a major challenge and many histological prognosticators have been applied because of the ease and simplicity of using them in day-to-day practice. Our histopathologic observation on 96 oral squamous cell carcinoma (OSCC) specimens revealed 34 cases associated with frank hemorrhagic areas, which were close to tumor cells. Hence, we propose that there could be a cross-talk between tumor cells and RBCs which can modulate the biological behavior of the tumor and prognosis of the patient. In the present paper, a scientific foundation is provided for this proposition. Furthermore, an experimental approach is recommended which will facilitate the identification of extracellular metabolites within the tumor microenvironment near RBCs. Such studies may pave the way for a better understanding of the clinical heterogeneity of oral cancer due to differential heme content of red blood cells (RBCs) in the tumor microenvironment (TME).

EMMPRIN/BASIGIN as a biological modulator of oral cancer and COVID-19 interaction: Novel propositions.

Extracellular matrix metalloproteinase inducer (EMMPRIN), which is also called BASIGIN/CD147, is a cell surface glycoprotein that belongs to the immunoglobulin superfamily and plays a significant role in intercellular recognition in immunology, cellular differentiation and development. Apart from ACE-2, recently EMMPRIN, has been regarded as a target for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) attachment and entry into the host cell. Since one of the routes of entry for the virus is the oral cavity, it becomes imperative to percept oral comorbidities such oral squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMDs) in terms of EMMPRIN as a target for SARS-CoV-2. In the present paper, it is proposed that OSCC, by the virtue of upregulation of EMMPRIN expression, increases the susceptibility to coronavirus disease (COVID-19). In turn, COVID-19 in OSCC patients causes exhaustion of EMMPRIN receptor due to binding with 'S' receptor leading to a downregulation of related carcinogenesis events. We proposed that in the ACE-2 depleted situation in OSCC, EMMPRIN receptor might get high jacked by the COVID-19 virus for the entry into the host cells. Apart from the anti-monoclonal antibody, it is recommended to explore the use of grape seed and skin containing mouthwash as an adjunct, which could also have anti EMMPRIN effects in patients with OSCC and OPMDs.

Extrachromosomal circular DNAs: an extra piece of evidence to depict tumor heterogeneity.

The tumor microenvironment (TME) comprises a heterogeneous number and type of cellular and noncellular components that vary in the context of molecular, genomic and epigenomic levels. The genotypic diversity and plasticity within cancer cells are known to be affected by genomic instability and genome alterations. Besides genomic instability within the chromosomal linear DNA, an extra factor appears in the form of extrachromosomal circular DNAs (eccDNAs; 2-20 kbp) and microDNAs (200-400 bp). This extra heterogeneity within cancer cells in the form of an abundance of eccDNAs adds another dimension to the expression of procancer players, such as oncoproteins, acting as a driver for cancer cell survival and proliferation. This article reviews research into eccDNAs centering around cancer plasticity and hallmarks, and discusses these facts in light of therapeutics and biomarker development.

Removal of aromatic inhibitors produced from lignocellulosic hydrolysates by Acinetobacter baylyi ADP1 with formation of ethanol by Kluyveromyces marxianus.

BACKGROUND: Lignocellulosic biomass is an attractive, inexpensive source of potentially fermentable sugars. However, hydrolysis of lignocellulose results in a complex mixture containing microbial inhibitors at variable composition. A single microbial species is unable to detoxify or even tolerate these non-sugar components while converting the sugar mixtures effectively to a product of interest. Often multiple substrates are metabolized sequentially because of microbial regulatory mechanisms. To overcome these problems, we engineered strains of Acinetobacter baylyi ADP1 to comprise a consortium able to degrade benzoate and 4-hydroxybenzoate simultaneously under batch and continuous conditions in the presence of sugars. We furthermore used a thermotolerant yeast, Kluyveromyces marxianus, to convert the glucose remaining after detoxification to ethanol. RESULTS: The two engineered strains, one unable to metabolize benzoate and another unable to metabolize 4-hydroxybenzoate, when grown together removed these two inhibitors simultaneously under batch conditions. Under continuous conditions, a single strain with a deletion in the gcd gene metabolized both inhibitors in the presence of sugars. After this batch detoxification using ADP1-derived mutants, K. marxianus generated 36.6 g/L ethanol. CONCLUSIONS: We demonstrated approaches for the simultaneous removal of two aromatic inhibitors from a simulated lignocellulosic hydrolysate. A two-stage batch process converted the residual sugar into a non-growth-associated product, ethanol. Such a two-stage process with bacteria (A. baylyi) and yeast (K. marxianus) is advantageous, because the yeast fermentation occurs at a higher temperature which prevents growth and ethanol consumption of A. baylyi. Conceptually, the process can be extended to other inhibitors or sugars found in real hydrolysates. That is, additional strains which degrade components of lignocellulosic hydrolysates could be made substrate-selective and targeted for use with specific complex mixtures found in a hydrolysate.

Induction of Apoptotic Death and Cell Cycle Arrest in HeLa Cells by Extracellular Factors of Breast Cancer Cells

Background: There are evidences on the role of extracellular factors in cellular communication between cancer cells and non-cancerous cells to support tumor progression and a phenomenon of cancer cachexia. However, evidences are scarce to show the effects of extracellular factors from one carcinoma microenvironment upon growth and survival of another carcinoma. Methodology: To address the above issue, we have selected excised breast carcinoma tissue samples and in vitro grown MCF-7 sources of extracellular factors and tested their effects to evaluate growth and proliferation inhibitory potential against a cervical carcinoma cell line HeLa. Results: Data from the in vitro experiments like Trypan blue dye exclusion, MTT assay, cell cycle assay and annexin V/PI staining lead us to suggest that the extracellular factors collected from the culture medium of in vitro grown MCF-7 and excised breast carcinoma tissue play an apoptosis inducing and cell cycle arrest role in HeLa. In these in vitro experiments, we detected the presence of up to 40-50% apoptotic cell death in HeLa cells and increase in G2-M cell cycle phase from 11%-25% due to treatment with extracellular factors from human breast carcinoma cells. Discussion and Conclusion: These observations are novel and suggest that extracellular factors from breast carcinoma play an apoptosis inducing and growth inhibitory role upon on HeLa cells. This study can also support the concept of cancer cachexia and a possible hypothesis for rare chance of synchronous two or more primary tumor in a single patient.

Potential of Taming MicroRNA on Driver Seat to Control Mitochondrial Horses in Breast Carcinoma.

Breast cancer among women is one of the most common carcinomas worldwide. Compared to developed countries, the breast cancer cases reported in India have boosted rapidly. At the same time, alarming statistics show that ratio of mortality cases over the total incidences is significantly high in comparison to developed world (Global Heath Estimates, WHO 2015). In recent times, several oncogenic signaling pathways have shown convergent effects on various types of cancer cell metabolism including breast cancer leading to tumor development. In 1931, German biochemist Otto Warburg revealed that cancer cells burn sugar (glycolysis) differently than normal cells. Cancer cells prefer to burn sugar over energy rich fats even when cellular oxygen conditions favor mitochondrial fat burning. Further, Warburg hypothesized that cancer is caused by mitochondrial dysfunction forcing the cells to use aerobic glycolysis instead of oxidative phosphorylation (OXPHOS). MicroRNAs (miRNAs) are critical classes of small ~22 nt non-coding endogenous RNAs implicated in gene expression regulation. To date, miRNAs have shown to regulate many cellular metabolic pathways critical for breast carcinoma patho-physiology. There is common consent that miRNAs dedicated to mitochondria and cellular metabolism have profound positive effects on breast carcinoma survival and metastasis. Therefore, in future there is huge scope for identification of miRNA types playing as a driver in mitochondria for breast tumor development. Further, several strategies to taming as well as knocking down these miRNA in breast tumor would be one of the fascinating approaches in medical sciences and cancer therapy. Here, we review updated scientific findings and possible therapeutic interventions with reference to miRNAs, mitochondria, cellular metabolism and breast carcinoma.

Effect of Evolutionary Adaption on Xylosidase Activity in Thermotolerant Yeast Isolates Kluyveromyces marxianus NIRE-K1 and NIRE-K3.

Efficient use of xylose along with glucose is necessary for the economic production of lignocellulosic based biofuels. Xylose transporters play an important role in the microorganisms for efficient utilization of xylose. In the present study, a novel method has been developed for a rapid assay of xylose transport activity in the xylose-utilizing isolates and other known yeasts. An assay was conducted to compare the activity of ß-xylosidase using p-nitrophenyl-ß-D-xylopyranoside (pNPX) in the intact, intracellular, and extracellular yeasts cells showing xylose transporter. Saccharomyces cerevisiae (MTCC 170) showed no xylosidase activity, while little growth was observed in the xylose-containing medium. Although other yeasts, i.e., Kluyveromyces marxianus NIRE-K1 (MTCC 5933), K. marxianus NIRE-K3 (MTCC 5934), and Candida tropicalis (MTCC 230), showed xylosidase activity in intact, intracellular, and extracellular culture. The xylosidase activity in intact cell was higher than that of extracellular and intracellular activity in all the yeast cells. The enzyme activity was higher in case of K. marxianus NIRE-K1 and K. marxianus NIRE-K3 rather than the C. tropicalis. Further, better xylosidase activity was observed in adapted K. marxianus cells which were 2.79-28.46 % higher than that of native (non-adapted) strains, which indicates the significant improvement in xylose transportation.

A new search for thermotolerant yeasts, its characterization and optimization using response surface methodology for ethanol production.

The progressive rise in energy crisis followed by green house gas (GHG) emissions is serving as the driving force for bioethanol production from renewable resources. Current bioethanol research focuses on lignocellulosic feedstocks as these are abundantly available, renewable, sustainable and exhibit no competition between the crops for food and fuel. However, the technologies in use have some drawbacks including incapability of pentose fermentation, reduced tolerance to products formed, costly processes, etc. Therefore, the present study was carried out with the objective of isolating hexose and pentose fermenting thermophilic/thermotolerant ethanologens with acceptable product yield. Two thermotolerant isolates, NIRE-K1 and NIRE-K3 were screened for fermenting both glucose and xylose and identified as Kluyveromyces marxianus NIRE-K1 and K. marxianus NIRE-K3. After optimization using Face-centered Central Composite Design (FCCD), the growth parameters like temperature and pH were found to be 45.17°C and 5.49, respectively for K. marxianus NIRE-K1 and 45.41°C and 5.24, respectively for K. marxianus NIRE-K3. Further, batch fermentations were carried out under optimized conditions, where K. marxianus NIRE-K3 was found to be superior over K. marxianus NIRE-K1. Ethanol yield (Y x∕s ), sugar to ethanol conversion rate (%), microbial biomass concentration (X) and volumetric product productivity (Q p ) obtained by K. marxianus NIRE-K3 were found to be 9.3, 9.55, 14.63, and 31.94% higher than that of K. marxianus NIRE-K1, respectively. This study revealed the promising potential of both the screened thermotolerant isolates for bioethanol production.

Nitric Oxide Down-Regulates Topoisomerase I and Induces Camptothecin Resistance in Human Breast MCF-7 Tumor Cells.

Camptothecin (CPT), a topoisomerase I poison, is an important drug for the treatment of solid tumors in the clinic. Nitric oxide (·NO), a physiological signaling molecule, is involved in many cellular functions, including cell proliferation, survival and death. We have previously shown that ·NO plays a significant role in the detoxification of etoposide (VP-16), a topoisomerase II poison in vitro and in human melanoma cells. ·NO/·NO-derived species are reported to modulate activity of several important cellular proteins. As topoisomerases contain a number of free sulfhydryl groups which may be targets of ·NO/·NO-derived species, we have investigated the roles of ·NO/·NO-derived species in the stability and activity of topo I. Here we show that ·NO/·NO-derived species induces a significant down-regulation of topoisomerase I protein via the ubiquitin/26S proteasome pathway in human colon (HT-29) and breast (MCF-7) cancer cell lines. Importantly, ·NO treatment induced a significant resistance to CPT only in MCF-7 cells. This resistance to CPT did not result from loss of topoisomerase I activity as there were no differences in topoisomerase I-induced DNA cleavage in vitro or in tumor cells, but resulted from the stabilization/induction of bcl2 protein. This up-regulation of bcl2 protein in MCF-7 cells was wtp53 dependent as pifithrine-α, a small molecule inhibitor of wtp53 function, completely reversed CPT resistance, suggesting that wtp53 and bcl2 proteins played important roles in CPT resistance. Because tumors in vivo are heterogeneous and contaminated by infiltrating macrophages, ·NO-induced down-regulation of topoisomerase I protein combined with bcl2 protein stabilization could render certain tumors highly resistant to CPT and drugs derived from it in the clinic.

Intrinsic mitochondrial DNA repair defects in Ataxia Telangiectasia.

Ataxia Telangiectasia (A-T) is a progressive childhood disorder characterized most notably by cerebellar degeneration and predisposition to cancer. A-T is caused by mutations in the kinase ATM, a master regulator of the DNA double-strand break response. In addition to DNA-damage signaling defects, A-T cells display mitochondrial dysfunction that is thought to contribute to A-T pathogenesis. However, the molecular mechanism leading to mitochondrial dysfunction in A-T remains unclear. Here, we show that lack of ATM leads to reduced mitochondrial DNA (mtDNA) integrity and mitochondrial dysfunction, which are associated to defective mtDNA repair. While protein levels of mtDNA repair proteins are essentially normal, in the absence of ATM levels specifically of DNA ligase III (Lig3), the only DNA ligase working in mitochondria is reduced. The reduction of Lig3 is observed in different A-T patient cells, in brain and pre-B cells derived from ATM knockout mice as well as upon transient or stable knockdown of ATM. Furthermore, pharmacological inhibition of Lig3 in wild type cells phenocopies the mtDNA repair defects observed in A-T patient cells. As targeted deletion of LIG3 in the central nervous system causes debilitating ataxia in mice, reduced Lig3 protein levels and the consequent mtDNA repair defect may contribute to A-T neurodegeneration. A-T is thus the first disease characterized by diminished Lig3.