The principles of ELISA and its application Essay

The principles of ELISA and its application - Essay Example The sensitivity of simple enzyme assays together with the specificity of antibodies/antigens aid in qualitative and quantitative determination of antigen or antibody concentration in samples. The various biological samples, like plasma, serum, urine, and cell extracts containing unknown antigen/antibody concentration can be analysed in ELISA. This biochemical technique employs polyclonal or monoclonal antibodies depending upon the specificity requirement for the sample to be assayed. The assays involving monoclonal antibodies increases specificity; and therefore give reproducible and accurate results. The enzymes employed in ELISA should be simple, easily analysed and should have a high turnover number. The substrates used for the enzyme assay should be stable, safe, inexpensive, and should generate soluble end products. The chromogenic colourless substrates are utilized which give colored reaction products after the reaction. This visible color reaction is quantified spectrophotomet rically. Other options for detection include analysis using fluorescent or radioactive probes.The most commonly used enzymes in ELISA are horse raddish peroxidase, alkaline phosphatase, urease, ÃŽ ²-galactosidase etc. (Axel 1999). When alkaline phosphatase is used for labeling the antibody, p-nitrophenylphosphate (pNPP) is used as substrate which forms yellow color product p-nitrophenol after the reaction. The chromogneic substrates employed with peroxidase are 2,2’-azo-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), o-phenylenediamine (OPD) and 3,3’5,5’- tetramethylbenzidine base (TMB), which gives end products with green, orange and blue colors, respectively. A 96-well microtiter plate is used to execute the ELISA constituted of polystyrene or PVC. Direct ELISA: In this technique, a sample containing the target antigen is adsorbed in a well of the microtiter plate. An enzyme labeled primary antibody reacts directly with the antigen. Direct ELISA excludes the use of

National Health and Nutrition Examination Survey Speech or Presentation

National Health and Nutrition Examination Survey - Speech or Presentation Example Their data is comprehensive and nationally representative, drawing from a large and diverse sample of participants. Current presentation focuses on the contribution made by NHANES to research chronic disease like obesity and hearing disorders and infectious disease like tuberculosis (TB). Current trends and risk factors associated with these disorders are also highlighted. Is there a fine line between healthy weight and overweight, or between overweight and obesity? Body mass index (BMI) is a widely used tool to determine overall health and nutritional status of individuals over time. NHANES have made a significant contribution in studying weight issues. Their reports indicate that the percent of overweight and obese adults is continuing to increase (NHANES). The percent of people, who are overweight or obese, with a BMI of 25.0 or higher, increased from 56 percent in 1988-1994 to 64 percent in 1999–2000. Moreover if we look at the longer period from 1960s to 2000, there is ab out 18% decline in healthy weight. The bottom line is that there is increase in the prevalence of obesity in men and women both, and in all age groups (20-72 years) (Flagel et al., 1723-27). These numbers obviously raise question about the implication of these trends on health outcomes since obesity is a risk factors for many chronic diseases like arthritis, diabetes, hypertension, cardiovascular diseases, and some types of cancers. Diabetes is more closely linked to obesity and its prevalence is also increasing along with obesity. Lifestyle change, education, low fat-low energy diet and regular physical activity can bring a modest change of 5-10% reduction in body weight. The benefits of reduction in overweight and obesity are of significant public health importance. Hearing disorder is another chronic disease affecting tens of millions of people in US. A maximal threshold levels that range from 15 dB to 25 dB can be defined as normal hearing. Loud sound exposure is one of the risk factors for acquired loss of hearing. NHANES report that infection, genetic syndromes, complications of prematurity, perinatal complications, ototoxic medications, and head trauma are other possible risk factors for this disease. According to NHANES, the prevalence of hearing loss in adolescents aged 12-19 years in significantly increasing. It increased from 14.9 % in 1988-1994 to 15.2-23.8% in 2005-2006 (Shargorodsky et al 772-8). This is about 31% increase over these years. Both unilateral and bilateral hearing loss showed increased incidences. Unilateral hearing loss increased from 11.1% to 14.0%, while bilateral hearing loss increased from 3.8% to 5.5% during these periods. NHANES 2005-2006 report show that 1 in every 5 adolescent demonstrated loss of hearing. 1 in every 20 adolescent has mild or worse hearing loss (>25dB). The interval factors between 1988-1994 and 2005-2006 like vaccination against influenza, pneumonia or awareness towards hearing loss due to loud music, had not effect on the reduction of hearing loss, although it was expected. Hearing loss at this age can affect learning, social skill development and self-esteem; hence it becomes important that young adults do no underestimate the symptoms of loud sound, tinnitus, and temporary hearing impairment during music exposure. Slight or worse hearing loss has also been associated with lower school grades, low self-esteem and increased stress. 2005-2006 NHANES report that higher incidences of hearing loss come from the participants living below the national