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The Science of the Total Environment Feb 2022Methane, a potent greenhouse gas of global importance, has traditionally been considered as an end product of microbial methanogenesis of organic matter. Paradoxically,... (Review)
Review
Methane, a potent greenhouse gas of global importance, has traditionally been considered as an end product of microbial methanogenesis of organic matter. Paradoxically, growing evidence has shown that some microbes, such as cyanobacteria, algae, fungi, purple non-sulfur bacteria, and cryptogamic covers, produce methane in oxygen-saturated aquatic and terrestrial ecosystems. The non-methanogenesis process could be an important potential contributor to methane emissions. This systematic review summarizes the knowledge of microorganisms involved in the non-methanogenesis process and the possible mechanisms of methane formation. Cyanobacteria-derived methane production may be attributed to either demethylation of methyl phosphonates or linked to light-driven primary productivity, while algae produce methane by utilizing methylated sulfur compounds as possible carbon precursors. In addition, fungi produce methane by utilizing methionine as a possible carbon precursor, and purple non-sulfur bacteria reduce carbon dioxide to methane by nitrogenase. The microbial methane distribution from the non-methanogenesis processes in aquatic and terrestrial environments and its environmental significance to global methane emissions, possible mechanisms of methane production in each open water, water-to-air methane fluxes, and the impact of climate change on microorganisms are also discussed. Finally, future perspectives are highlighted, such as establishing more in-situ experiments, quantifying methane flux through optimizing empirical models, distinguishing individual methane sources, and investigating nitrogenase-like enzyme systems to improve our understanding of microbial methane emission from the non-methanogenesis process.
Topics: Carbon Dioxide; Cyanobacteria; Ecosystem; Methane; Nitrogenase
PubMed: 34740653
DOI: 10.1016/j.scitotenv.2021.151362 -
Current Molecular Medicine 2022Backgound and objective: Early chemoprevention in Oral Potentially Malignant Disorders (OPMDs) and Oral Cancer (OC) has been extensively researched in order to mitigate...
Backgound and objective: Early chemoprevention in Oral Potentially Malignant Disorders (OPMDs) and Oral Cancer (OC) has been extensively researched in order to mitigate the malignant transformation and progression of the lesion. Many agents have been attempted, but their cost inefficacy and inadequate outcomes posed a major hindrance in their successful adoption. Retinoid Based Therapy (RBT) though a cheap and effective treatment option, could not achieve much clinical usage because of variable responsiveness in clinical outcomes. Such clinical response variability may be attributed to the repression of retinoid receptors by Preferentially Expressed Antigen of Melanoma (PRAME) protein molecule. Therefore, in order to make RBT successful, targeting PRAME by various immunotherapies is an exciting area of research investigation. This review provides an insight into the various immunotherapeutic strategies targeting PRAME and their usefulness in retinoid-resistant OPMD and OC. Method of data collection: An exhaustive internet-based literature search following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was carried out in PUBMED and Google SCHOLAR database using terms 'Anti-PRAME' OR 'PRAME Immunotherapy' OR 'PRAME Vaccines' AND 'Cancer' AND 'Retinoid resistance'. Only articles in the English language with at least 1 citation, published in a journal with impact factor ≥ 1, having relevance to the context and availability of full text were considered. Results: After an initial search, 342 articles were yielded on the basis of inclusion criteria and, by reading the abstract and availability of full text, a total of 124 articles were selected. Further reading the full texts and considering articles from the references of the selected articles, a total of 65 articles were finally included in the review. Conclusion: Our analysis of the literature suggests that PRAME screening in OC and OPMDs prior to RBT should be done. In PRAME positive cases, approaches like PRAME based immunotherapy in the form of Cancer vaccine therapy [Acellular PRAME vaccine, PRAME pulsed Dendritic Cells (DC)]; Adoptive T Cell therapy/T Cell Receptor-T Cell therapy, Antibody therapy/Chimeric Antigen Receptor-T Cell therapy along with Presented antigen modulation Therapies employing histone deacetylase inhibitors and demethylation agents seem plausible. In the future, a combination therapy employing either PRAME vaccines or antibodies or Adoptive T cell Therapy and ATRA could be used in retinoid resistant OC and OPMDs.
Topics: Antigens, Neoplasm; Humans; Immunotherapy; Mouth Neoplasms; Retinoids
PubMed: 34711164
DOI: 10.2174/1566524021666211027091719 -
Cancers Oct 2021The survival rate of head and neck squamous cell carcinoma patients with the current standard of care therapy is suboptimal and is associated with long-term side... (Review)
Review
The survival rate of head and neck squamous cell carcinoma patients with the current standard of care therapy is suboptimal and is associated with long-term side effects. Novel therapeutics that will improve survival rates while minimizing treatment-related side effects are the focus of active investigation. Epigenetic modifications have been recognized as potential therapeutic targets in various cancer types, including head and neck cancer. This review summarizes the current knowledge on the function of important epigenetic modifiers in head and neck cancer, their clinical implications and discusses results of clinical trials evaluating epigenetic interventions in past and ongoing clinical trials as monotherapy or combination therapy with either chemotherapy, radiotherapy or immunotherapy. Understanding the function of epigenetic modifiers in both preclinical and clinical settings will provide insight into a more rational design of clinical trials using epigenetic interventions and the patient subgroups that may benefit from such interventions.
PubMed: 34680389
DOI: 10.3390/cancers13205241 -
International Journal of Molecular... May 2021FLT3-mutated acute myeloid leukemia accounts for around 30% of acute myeloid leukemia (AML). The mutation carried a poor prognosis until the rise of tyrosine kinase...
FLT3-mutated acute myeloid leukemia accounts for around 30% of acute myeloid leukemia (AML). The mutation carried a poor prognosis until the rise of tyrosine kinase inhibitors (TKIs). New potent and specific inhibitors have successfully altered the course of the disease, increasing the complete response rate and the survival of patients with FLT3-mutated AML. The aim of this article is to review all the current knowledge on these game-changing drugs as well as the unsolved issues raised by their use for fit and unfit FLT3-mutated AML patients. To this end, we analyzed the results of phase I, II, III clinical trials evaluating FLT3-TKI both in the first-line, relapse monotherapy or in combination referenced in the PubMed, the American Society of Hematology, the European Hematology Association, and the Clinicaltrials.gov databases, as well as basic science reports on TKI resistance from the same databases. The review follows a chronological presentation of the different trials that allowed the development of first- and second-generation TKI and ends with a review of the current lines of evidence on leukemic blasts resistance mechanisms that allow them to escape TKI.
Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Clinical Trials as Topic; Databases, Factual; Drug Resistance, Neoplasm; Gene Expression; Humans; Leukemia, Myeloid, Acute; Mutation; Protein Kinase Inhibitors; Recurrence; Stem Cell Transplantation; Survival Analysis; Transplantation, Homologous; Treatment Outcome; fms-Like Tyrosine Kinase 3
PubMed: 34070902
DOI: 10.3390/ijms22115873 -
European Review For Medical and... Mar 2021Abnormal DNA methylation plays a critical role in acute myeloid leukemia (AML) pathogenesis and hypomethylating agents (HMAs) such as decitabine (5-aza-29-deoxycytidine)... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
Abnormal DNA methylation plays a critical role in acute myeloid leukemia (AML) pathogenesis and hypomethylating agents (HMAs) such as decitabine (5-aza-29-deoxycytidine) and azacitidine (5-azacytidine) are considered efficacious for treating AML. This study aimed to identify if HMAs have therapeutic advantages compared with conventional care regimens (CCR) or placebo in elderly AML patients.
MATERIALS AND METHODS
We systematically searched PubMed, Embase, and Cochrane Central Register of Controlled Trials from inception to November July 15, 2020. Randomized controlled trials that compared the efficacy and adverse events associated with HMAs, CCR, or placebo were searched. RevMan 5.3 software was used to calculate the hazard ratio (HR) and risk ratio (RR) with a 95% confidence interval (CI).
RESULTS
Seven trials with a total of 1966 participants were included. Meta-analyses showed that the overall survival of HMAs was better than that of CCR [HR=0.76, 95% CI (0.69-0.85), (p<0.01)], and the complete remission rate of elderly AML patients was increased by HMAs compared with CCR [RR=1.46, 95%CI (1.08-1.99), p=0.01)]. HMA treatment showed higher incidence of neutropenia [RR=1.30 (95%CI 1.07-1.59, p=0.008)], thrombocytopenia [RR=1.14 (95%CI 1.01-1.59, p=0.04)], and pneumonia [RR=1.37 (95%CI 1.06-1.76, p=0.02)] compared with CCR.
CONCLUSIONS
Although HMAs cause a higher incidence of adverse events such as neutropenia, thrombocytopenia, and pneumonia, demethylation drugs are well-tolerated and effective for treating AML in the elderly.
Topics: Aged; Antimetabolites, Antineoplastic; Azacitidine; Humans; Leukemia, Myeloid, Acute; Randomized Controlled Trials as Topic
PubMed: 33829444
DOI: 10.26355/eurrev_202103_25421 -
Frontiers in Pharmacology 2020Epimutations secondary to gene-environment interactions have a key role in the pathophysiology of major psychiatric disorders. and evidence suggest that mood...
BACKGROUND
Epimutations secondary to gene-environment interactions have a key role in the pathophysiology of major psychiatric disorders. and evidence suggest that mood stabilizers can potentially reverse epigenetic deregulations found in patients with schizophrenia or mood disorders through mechanisms that are not yet fully understood. However, their activity on epigenetic processes has made them a research target for therapeutic approaches.
METHODS
We conducted a comprehensive literature search of PubMed and EMBASE for studies investigating the specific epigenetic changes induced by non-antipsychotic mood stabilizers (valproate, lithium, lamotrigine, and carbamazepine) in animal models, human cell lines, or patients with schizophrenia, bipolar disorder, or major depressive disorder. Each paper was reviewed for the nature of research, the species and tissue examined, sample size, mood stabilizer, targeted gene, epigenetic changes found, and associated psychiatric disorder. Every article was appraised for quality using a modified published process and those who met a quality score of moderate or high were included.
RESULTS
A total of 2,429 records were identified; 1,956 records remained after duplicates were removed and were screened title, abstract and keywords; 129 records were selected for full-text screening and a remaining of 38 articles were included in the qualitative synthesis. Valproate and lithium were found to induce broader epigenetic changes through different mechanisms, mainly DNA demethylation and histones acetylation. There was less literature and hence smaller effects attributable to lamotrigine and carbamazepine could be associated overall with the small number of studies on these agents. Findings were congruent across sample types.
CONCLUSIONS
An advanced understanding of the specific epigenetic changes induced by classic mood stabilizers in patients with major psychiatric disorders will facilitate personalized interventions. Further related drug discovery should target the induction of selective chromatin remodeling and gene-specific expression effects.
PubMed: 32390836
DOI: 10.3389/fphar.2020.00467 -
Differential methylation landscape of pancreatic ductal adenocarcinoma and its precancerous lesions.Hepatobiliary & Pancreatic Diseases... Jun 2020Pancreatic cancer is one of the most lethal diseases with an incidence almost equal to the mortality. In addition to having genetic causes, cancer can also be considered...
BACKGROUND
Pancreatic cancer is one of the most lethal diseases with an incidence almost equal to the mortality. In addition to having genetic causes, cancer can also be considered an epigenetic disease. DNA methylation is the premier epigenetic modification and patterns of aberrant DNA methylation are recognized to be a common hallmark of human tumor. In the multistage carcinogenesis of pancreas starting from precancerous lesions to pancreatic ductal adenocarcinoma (PDAC), the epigenetic changes play a significant role.
DATA SOURCES
Relevant studies for this review were derived via an extensive literature search in PubMed via using various keywords such as pancreatic ductal adenocarcinoma, precancerous lesions, methylation profile, epigenetic biomarkers that are relevant directly or closely associated with the concerned area of our interest. The literature search was intensively done considering a time frame of 20 years (1998-2018).
RESULT
In this review we have highlighted the hypermethylation and hypomethylation of the precancerous PDAC lesions (pancreatic intra-epithelial neoplasia, intraductal papillary mucinous neoplasm, mucinous cystic neoplasm and chronic pancreatitis) and PDAC along with the potential biomarkers. We have also achieved the early epigenetic driver that leads to progression from precancerous lesions to PDAC. A bunch of epigenetic driver genes leads to progression of precancerous lesions to PDAC (ppENK, APC, p14/5/16/17, hMLH1 and MGMT) are also documented. We summarized the importance of these observations in therapeutics and diagnosis of PDAC hence identifying the potential use of epigenetic biomarkers in epigenetic targeted therapy. Epigenetic inactivation occurs by hypermethylation of CpG islands in the promoter regions of tumor suppressor genes. We listed all hyper- and hypomethylation of CpG islands of several genes in PDAC including its precancerous lesions.
CONCLUSIONS
The concept of the review would help to understand their biological effects, and to determine whether they may be successfully combined with other epigenetic drugs. However, we need to continue our research to develop more specific DNA-demethylating agents, which are the targets for hypermethylated CpG methylation sites.
Topics: Biomarkers, Tumor; Carcinogenesis; Carcinoma in Situ; Carcinoma, Pancreatic Ductal; DNA Methylation; Epigenesis, Genetic; Humans; Pancreatic Intraductal Neoplasms; Pancreatic Neoplasms; Pancreatitis, Chronic; Precancerous Conditions
PubMed: 32312637
DOI: 10.1016/j.hbpd.2020.03.010 -
The Science of the Total Environment Jun 2020The fate and transport of Hg species in natural aquatic environment are strongly affected by photochemical transformation of Hg, Hg, and MeHg. Migration of Hg is... (Review)
Review
The fate and transport of Hg species in natural aquatic environment are strongly affected by photochemical transformation of Hg, Hg, and MeHg. Migration of Hg is determined by its complexation with organic and inorganic ligands that are widely present in the water. The presence of dissolved organic matter (DOM) is closely related to photochemical reactions of Hg. DOM can strongly bind to mercury (e.g., Hg and MeHg), thus affecting its speciation, mobility and toxicity, eventually dominating its bioavailability. This review summarizes extensive studies on photochemical behaviors of Hg including: (1) photo-oxidation; (2) photo-reduction; (3) photochemical methylation; and (4) MeHg photo-degradation. Photo-oxidation of Hg is mostly caused by oxidative free radicals (e.g., •OH, CO, O, and O), while photo-reduction of Hg is more complicated and it involves two pathways: (1) primary processes (direct photolysis of Hg or ligand-metal charge transfer of Hg-DOM complex); and (2) secondary processes (reduction of Hg-DOM complex induced by free radicals derived from DOM photolysis). Photochemical methylation of inorganic Hg occurs as follows: (1) Hg complexes with methyl donors (e.g., acetic acid, tert-butyl, alcohols, etc.) to form intermediates, followed by (2) an intramolecular methyl transfer. MeHg photo-degradation is the leading pathway for MeHg demethylation and it primarily proceeds via four different pathways. The information on DOM was also mentioned, but DOM is not the only factor that affects the photochemical behaviors of Hg. Other influencing factors such as: (1) pH value; (2) dissolved oxygen; (3) cations (Fe, K) and anions (NO, HCO, CO, Cl); and (4) suspended substance cannot be ignored.
PubMed: 32143045
DOI: 10.1016/j.scitotenv.2020.137540 -
Human Reproduction Update Sep 2019A defining feature of sexual reproduction is the transmission of genomic information from both parents to the offspring. There is now compelling evidence that the...
BACKGROUND
A defining feature of sexual reproduction is the transmission of genomic information from both parents to the offspring. There is now compelling evidence that the inheritance of such genetic information is accompanied by additional epigenetic marks, or stable heritable information that is not accounted for by variations in DNA sequence. The reversible nature of epigenetic marks coupled with multiple rounds of epigenetic reprogramming that erase the majority of existing patterns have made the investigation of this phenomenon challenging. However, continual advances in molecular methods are allowing closer examination of the dynamic alterations to histone composition and DNA methylation patterns that accompany development and, in particular, how these modifications can occur in an individual's germline and be transmitted to the following generation. While the underlying mechanisms that permit this form of transgenerational inheritance remain unclear, it is increasingly apparent that a combination of genetic and epigenetic modifications plays major roles in determining the phenotypes of individuals and their offspring.
OBJECTIVE AND RATIONALE
Information pertaining to transgenerational inheritance was systematically reviewed focusing primarily on mammalian cells to the exclusion of inheritance in plants, due to inherent differences in the means by which information is transmitted between generations. The effects of environmental factors and biological processes on both epigenetic and genetic information were reviewed to determine their contribution to modulating inheritable phenotypes.
SEARCH METHODS
Articles indexed in PubMed were searched using keywords related to transgenerational inheritance, epigenetic modifications, paternal and maternal inheritable traits and environmental and biological factors influencing transgenerational modifications. We sought to clarify the role of epigenetic reprogramming events during the life cycle of mammals and provide a comprehensive review of how the genomic and epigenomic make-up of progenitors may determine the phenotype of its descendants.
OUTCOMES
We found strong evidence supporting the role of DNA methylation patterns, histone modifications and even non-protein-coding RNA in altering the epigenetic composition of individuals and producing stable epigenetic effects that were transmitted from parents to offspring, in both humans and rodent species. Multiple genomic domains and several histone modification sites were found to resist demethylation and endure genome-wide reprogramming events. Epigenetic modifications integrated into the genome of individuals were shown to modulate gene expression and activity at enhancer and promoter domains, while genetic mutations were shown to alter sequence availability for methylation and histone binding. Fundamentally, alterations to the nuclear composition of the germline in response to environmental factors, ageing, diet and toxicant exposure have the potential to become hereditably transmitted.
WIDER IMPLICATIONS
The environment influences the health and well-being of progeny by working through the germline to introduce spontaneous genetic mutations as well as a variety of epigenetic changes, including alterations in DNA methylation status and the post-translational modification of histones. In evolutionary terms, these changes create the phenotypic diversity that fuels the fires of natural selection. However, rather than being adaptive, such variation may also generate a plethora of pathological disease states ranging from dominant genetic disorders to neurological conditions, including spontaneous schizophrenia and autism.
Topics: Animals; Biological Evolution; DNA Methylation; Epigenesis, Genetic; Genome; Germ Cells; Heredity; Histone Code; Histones; Humans; Mammals; Mutation; Parents; Phenotype
PubMed: 31374565
DOI: 10.1093/humupd/dmz017 -
European Cardiology Jul 2019Acute coronary syndrome (ACS) is characterised by increased effector cells and decreased regulatory T-cells (Tregs). Statins have been shown to be clinically beneficial... (Review)
Review
The Effect of Statins on the Functionality of CD4+CD25+FOXP3+ Regulatory T-cells in Acute Coronary Syndrome: A Systematic Review and Meta-analysis of Randomised Controlled Trials in Asian Populations.
Acute coronary syndrome (ACS) is characterised by increased effector cells and decreased regulatory T-cells (Tregs). Statins have been shown to be clinically beneficial in ACS patients. This effect could be mediated via the induction of Tregs in ACS patients. The aim of this systemic review and meta-analysis was to evaluate whether statin therapy enhances the frequency of Tregs determined by CD4+CD25+FOXP3+ in this subset of patients. A comprehensive search of PubMed and Embase was performed. Studies were restricted to randomised controlled trials that quantified CD4+CD25+FOXP3+ cell frequency by flow cytometric analysis before and after statin treatment in adults diagnosed with ACS. A minimum of at least two of the conventional markers to identify Tregs was compulsory. Four randomised controlled trials studies (439 participants) were included, all with low-to-moderate risk of bias. Pooled data showed a significant increase in Treg frequency after statin therapy in ACS patients. A further meta-regression and subgroup analysis also showed a negative dose-related effect, and a statin type-related effect (rosuvastatin versus atorvastatin), respectively. The results confirmed that statins positively alter the frequency of Tregs, which may indicate a potential mechanism of their therapeutic effect. However, there was a risk of information bias due to the markers used to identify Tregs, which was not fully explored, therefore, further randomised controlled trials should utilise markers of Tregs, such as the FOXP3 locus (Treg-specific demethylated region), for identification.
PubMed: 31360235
DOI: 10.15420/ecr.2019.9.2