The world is experiencing an unprecedented challenge due to coronavirus disease (COVID-19) pandemic. In December 2019, a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as the cause of a cluster of pneumonia cases in Wuhan, a city in the Hubei province of China. It rapidly spread, resulting in an outbreak of COVID-19. Although the majority of the infected individuals exhibit mild to moderate respiratory illness and recover without requiring special treatment, older people and those with underlying medical problems like cardiovascular disease, diabetes, chronic respiratory disease, and cancer may rapidly progress to acute respiratory distress syndrome, septic shock, coagulation disorders, multi-organ failure, and death. The course of COVID-19 is usually mild in children. However, in rare cases, children can be severely affected, and clinical manifestations may differ from adults. Some children present the multisystem inflammatory syndrome that is similar to incomplete Kawasaki disease or toxic shock syndrome. There is no specific treatment and vaccine for COVID-19. Due to the high infectivity rate of COVID-19, the unexpected and rapid influx of large numbers of patients, especially patients who need intensive care, have caused great pressure on the health care systems worldwide. The worldwide spread of COVID-19 caused fear, anxiety, depression, panic attacks, and a general decrease in overall wellbeing in the population. Healthcare professionals who occupy the front-line during pandemics are at increased risk concerning their physical and mental health. The outbreak of COVID-19 negatively affected all aspects of life including education, trade, and tourism. Our knowledge of this novel virus is limited. However, many ongoing clinical trials are evaluating potential treatments and vaccines. A better understanding of the pathogenesis of COVID-19 will provide important insight into its management and reduce the mortality rate. Based on the latest global scientific data and clinical experiences of the authors, this book gives the readers an overview of COVID-19 pathogenesis and transmission routes, current diagnostic and treatment strategies, the clinical course of the disease in children and elderly patients, the genetic background of differences in the incidence of new SARS-CoV-2 infection, the impact of the COVID-19 pandemic on patients with chronic diseases such as diabetes, cancer, cardiovascular diseases, chronic respiratory diseases, antioxidant therapy to limit tissue damage, molecular approaches in COVID-19 treatment, and vaccine studies.

Many cancers are associated with the abnormal production of some molecules which can be measured in plasma/urine or can be detected on the surface of resected tumour tissue. These molecules are known as tumour markers. The potential uses of tumour markers are screening in the general population, differential diagnoses of symptomatic patients, clinical staging of cancer, estimating tumour volume, indicating prognosis, monitoring treatment and detecting recurrences. In order to obtain maximum clinical benefit, a tumour marker should have some characteristics. A tumour marker should be tissue-specific. The plasma level of the tumour marker should be in proportion to the size and activity of the tumour. A tumour marker should be present in plasma at a detectable level, even though tumour size is very small. A tumour marker should reflect the altered tumour characteristic as a response to therapy. Unfortunately, currently used tumour markers do not meet all of these criteria. A majority of them are present in normal, benign and tumour tissues, and unfortunately, they are not specific enough to be used for cancer screening in the general population. In addition, conventional tumour markers are poor in reflecting altered tumour behavior in response to anticancer therapy. They are of most value during follow-up appointments. Recent developments in molecular biology have led to the identification of numerous new tumour biomarkers. Firstly, the detection of DNA and RNA freely circulating in blood has provided a new perspective for the early diagnosis of cancer, patient follow-up, and assessment of therapy efficacy. Circulating free nucleic acids can originate from both malignant and non-malignant tissues. Discrimination of tumour cells is based on the presence of tumour-specific genetic and epigenetic alterations. This circulating nucleic acid-based approach is termed a liquid biopsy. Due to its non-invasive and repeatable features, liquid biopsy is a promising tool for cancer patients. It is particularly helpful in cancers where solid tissue biopsies are not feasible, and in the metastatic patients when multiple distinct tumour masses are simultaneously present. As another advantage, liquid biopsy shows the current tumour dynamics during anticancer therapy and drug sensitivities that conventional examinations fail to reflect. Secondly, self-renewable stem cells have the potential to cause cancer. If stem cells are genetically or epienetically changed, their differentiation potential becomes impaired and their proliferative capacity becomes uncontrolled. Current anticancer therapies mostly fail to eradicate cancer stem cells and instead favor expansion of the cancer stem cell pool and/or select for resistant stem cells. Thirdly, microRNAs, non-coding RNAs and transfer RNA fragments found in the bloodstream are candidate markers for the diagnosis and prognosis of different types of cancer. This book provides an overview of these new molecular tumour markers.

Epigenetics is a relatively new field of science explaining heritable changes that are not caused by alterations in DNA sequences. Epigenetic modifications are acquired throughout life, and depend on environmental clues such as diet, lifestyle and toxin exposure. It is possible to pass down epigenetic modifications to the next generation of offspring if the modifications occur in sperm or egg cells. Additionally, epigenetic regulations are central to many cellular processes such as imprinting, X chromosome inactivation, DNA damage response, cellular reprogramming and senescence. This book provides an overview for the influence of early life nutrition on the epigenome and the role of epigenetic dysregulations in the pathogenesis of many common diseases.

In the human body, iron is present in all cells and has several vital functions: as a carrier of oxygen to the tissues from the lungs in the form of hemoglobin; as a transport medium for electrons within the cells in the form of cytochromes and as an integral part of enzyme reactions in various tissues. Too little iron can interfere with these vital functions and lead to morbidity and death. This book presents current research from across the globe in the study of iron deficiency, including iron deficiency anemia in pregnant women and in gastric bypass surgery patients; the metabolic adjustment under Fe deficiency in roots of dicotyledonous plants and strategies for the fortification of food with iron.

Alkylating agents are an important class of carcinogens. O6-methylguanine (O6 MG) formed in cellular DNA by alkylating agents is a mutagenic lesion. Reactive metabolites, which are capable of alkylate in the DNA base, are produced during the catabolism of precursors of alkylating agents in the diet. Active alkylating agents can also be synthesised endogenously in the body. Endogenous alkylating agents are produced via nitrosation of primary amines by nitrates and nitrous anhydride formed by nitric oxide. Exposure of alkylating agents is at a minimum level in daily life. On the other hand, alkylating agents are used in certain chemotherapy regimens. Various investigators determined that O6-MGMT is at a high level in human tumours, thus they exhibit resistance to chemotherapy, including alkylating agents. Various anaolgs of O6-MG were suggested as a potential adjuvant in combination chemotherapy with alkylating agents to treat O6-MGMT proficient tumours. The susceptibility of any tissue to mutagenic effect of alkylating agents is dependent upon the balance between the ability of the tissue to metabolise alkylating agents to carcinogenic intermediates, the extent of O6-MG formation, rate of repair by O6-MGMT, and the extent of DNA replication which occurs when O6-MG is present. This book is a reliable reference for the sources of alkylating agents and their effects in human body.