DNA Damage and Repair

Exogenous or external processes and internal metabolic processes of the body contribute thousand to a million DNA damaging events per day (Dexheimer, 2013; Sigma-Aldrich, 2007). Errors, damages and chemical changes of the DNA molecules are identified and corrected in the DNA repair process. DNA repair involves the identification of DNA errors and maintenance of the errors to prevent cell death or remove cancerous cells (Sixth framework programme, 2009).

Mismatches of the nitrogenous bases, breaks in the backbone and crosslinks of the covalent linkages between the bases are common types of DNA damage (users.rcn.com, 2013). Direct DNA damage or crosslinking between adjacent cytosine and thymine bases creating pyrimidine dimers is caused by UV-B and indirect damage or free radicals formation is caused by UV-A (University of Leicester, 2010). Processes such as replication or transcription can be affected by DNA damage and mutations can be induced causing cancer (Dexheimer, 2013).

UV-radiation, gamma rays, X-rays, oxygen radicals and other chemicals act as agents to damage the DNA molecules (users.rcn.com, 2013). Chemical causing DNA damage includes alkylating agents such as methyl methanesulfonate, temozolomide, nitrogen mustards, chemotherapeutic drugs such as topoisomerase I or II inhibitors and other chemicals such as N-nitrosomines, heterocyclic amines and benzo-a-pyrenre (Dexheimer, 2013). According to University of Leicester (2010), industrial chemicals such as vinyl chloride and hydrogen peroxide, and environmental chemicals such as polycyclic hydrocarbons cause DNA damages. DNA repair mechanisms include base excision repair, mismatch repair, nucleotide excision repair and double strand break repair (Dexheimer, 2013; Sixth framework programme, 2009).

 

 

References

Dexheimer, T.S. (2013) DNA Repair Pathways and Mechanisms. Mathews, L.A. (eds)(2013) DNA Repair of Cancer Stem Cells. Springer. [Online] Available at www.springer.com [Accessed on 26 March 2014].

Sixth Framework Programme (2009) DNA Damage Response and Repair Mechanisms [Online] Available at http://www.dna-repair.nl [Accessed on 29 March 2014].

Sigma-Aldrich (2007) DNA Damage and Repair [Online] Available at www.sigmaaldrich.com [Accessed on 20 March 2014].

University of Leicester (2010) DNA Replication and Repair [Online] Available at www2.le.ac.uk [Accessed on 29 March 2014].

Users.rcn.com (2013) DNA Repair [Online] Available at http://www.users.rcn.com [Accessed on 20 March 2014].

Pulmonary Atresia

Pulmonary valve lets the blood flow in pulmonary artery between the right ventricle and lungs for oxygenation. Blockage of blood flow between the right ventricle and pulmonary artery due to narrowing or absence of pulmonary valve causes pulmonary atresia (AHA, 2009). The flow of oxygen-rich blood (red in color) into the lung is obstructed and low-oxygen blood (blue-in-color) circulates in the body which causes blue appearance of the child (AHA, 2009; BHF, 2010).

Wide range of the levels of defect can be found. Rodriguez-Cruz (2013) suggested considering the pulmonary atresia with ventricular septal defect as most severe. According to Rodriguez-Cruz (2013), the prevalence of pulmonary atresia is higher in males and children of patients with the defect. Ultrasound scan of the heart or echo cardiogram, chest radiography and MRI are diagnostic tools for pulmonary atresia (BHF, 2010).

Treatment of pulmonary atresia involves maintaining the normal blood flow and correcting the septal defects. Palliative treatment or the improvement of the heart condition is one of the treatment methods of pulmonary atresia but complete repair may also be possible with several operations (CHFED, n.d.; Royal Children’s Hospital, 2012). Percutaneous perforation of pulmonary valve and dilation of the valve is carried out in palliative surgery (Rodriguez-Cruz, 2013).

Valvotomy, Shunt operation, heart catheterization and heart-lung transplantation are treatment options for pulmonary atresia (Rodriguez-Cruz, 2013). According to BHF (2010), valvotomy or the process of opening the blocked valve can be catheter valvotomy or surgical valvotomy. Shunt or tube is the synthetic material placed between the pulmonary artery and the aorta (Cave Point Foundation, 2011).

References
American Heart Association (AHA) (2009) Pulmonary Atresia/ Intact Ventricular Septum. [Online] http://www.heart.org/idc/ [Accessed on 5 June 2013].

British Heart Foundation (BHF) (2006) Understanding Your Child’s Heart Pulmonary Atresia with Intact Ventricular Septum. [Online] Available at http://www.bhf.org.uk [Accessed on 6 June].

Cave Point Foundation (2011) Congenital Heart Disease. [Online] Available at http://www.pted.org/ [Accessed on 17 June 2013].

Children’s Heart Federation (CHFED, n.d.) Pulmonary Atresia with Intact Ventricular Septum. [Online] Available at http://www.youngatheart.org.uk/ [Accessed on 6 June 2013].

Rodriguez-Cruz, E. (2013) Pulmonary Atresia with Ventricular Septal Defect Treatment and Management. [Online] Available at http://emedicine.medscape.com/%5BAccessed on 17 June 2013].

Royal Children’s Hospital Melbourne (2012) Pulmonary Atresia with Intact Ventricular Septum. [Online] Available at http://www.rch.org.au/ [Accessed on 6 June 2013].

DNA Fingerprinting

Technology has a vital role in the assessment and diagnosis of health problems. Fingerprinting technology is useful in health science research. Every Individual’s DNA has specific patterns and DNA fingerprinting is used to identify the patterns of DNA (Forensic Science, 2014). Personal identification can be tested and proved with DNA fingerprinting. Restricted fragment length polymorphism (RFLP), Polymerase Chain Reaction (PCR), Amplified fragment length polymorphism (AmpFLP) and short Tandem Repeat (STR) are main DNA fingerprinting methods (fingerprinting, 2014).  Hair, tissue and blood samples are used for DNA fingerprinting. Study cases, study questions and organisms are considered to select DNA finger printing technique (Chai, 2008).

DNA fingerprinting technology can be useful to find out the genetic traits of living beings and even dead bodies. According to Templeton (2013), DNA printing can be applied in synthetic biology to create a new life by substituting a genome. DNA printing is a quicker and less expensive method for gene therapy, working with viral genes and vaccine research (Templeton, 2013).

DNA printing has a wide range of applications including paternity disputes, identification of bodies of soldiers killed in war, diagnosis of inherited disorders like cystic fibrosis, sickle cell anaemia, thalassemia, haemophilia, Alzheimer’s disease, Huntington’s chorea and marfan’s syndrome (Medindia, 2014). DNA printing can be used in biological evidence to identify criminals and data storage of personal identifications (medindia, 2014). Cossins (2012) mentioned about a geneticist Craig Venter for his idea about a 3D DNA printer. The proposed 3D DNA printer can download, print and inject vaccines at home.

 

References

Chai, H. (2008) DNA Fingerprinting using Amplified Fragment Length Polymorphisms (AFLP) Nature Education 1(1): 176.

Cossins, D. (2012) Venter Supports DNA Printers [Online] Available at www.the-scientist.com [Accessed on 31 January 2014].

Fingerprinting (2014) DNA Fingerprinting Methods [Online] www.fingerprinting.com [Accessed on 29 January 2014].

Forensic Science (2014) Guide to DNA Fingerprinting [Online] Available at www.forensicscience.org [Online] Available at www.forensicscience.org [Accessed on 29 January 2014].

Medindia (2014) DNA Fingerprinting [Online] Available at www.medindia.net [Accessed on 31 January 2014].

Templeton, G. (2013) DNA Laser Printing Heralds New Day for Genomics Research [Online] Available at www.extremetech.com [Accessed on 31 January 2014].