BIOCHEMISTRY, BIOMEDICINE & PHARMACEUTICS

Adeno associated virus (AAV) is a naturally occurring single-stranded DNA virus that belongs to the parvovirus family. The commonly used viral vectors for gene therapy are derived from naturally occurring AAVs. These vectors are genetically modified/engineered that do not contain and devoid of genes encoding viral proteins critical for their viral replication. The viral gene is replaced with the transgene of interest is packaged into the AAV viral capsid and administration to humans. The AAV viral vectors enable attachment and entry of transgene into the target cells. Once inside the cell nucleus, the transgene remains in the episomal form and expresses the gene of interest. Although recent evidence has shown that long-term stable expression of these transgenes can be achieved in pre-clinical models and humans, there is inherent immunogenicity risk associated with adeno-associated vectors which include: -Pre-existing antibodies and T cell response against viral vectors -Neutralizing an...

What are Hemophilia disorders ? Hemophilia is the group of bleeding disorders that are caused by a deficiency of proteins (factors) of the blood clotting cascade. Hemophilia A is caused by the deficiency of factor VIII protein and Hemophilia B is caused by a downstream protein factor IX. The deficiency of the factors VIII and IX affect the clotting cascade, resulting in higher and spontaneous bleeding episodes. The severe bleeding disorder leads to spontaneous bleeding in joints and soft tissue resulting in arthropathy; and increased risk of intravascular and intracranial hemorrhage. Why the development of new treatment paradigm is necessary? The standard treatment for hemophilia (A and B type) is the intravenous infusion of an exogenous clotting protein more than once a week to prevent bleeding. In addition, the development of inhibitors decreases the efficacy of the exogenous replacement factor and the severe hemophilia patients do not respond to these therapies.  There...

Inherited Biallelic RPE65 Mutation-Associated Retinal Dystrophy Inherited retinal dystrophies are a group of rare blinding conditions that are associated with progressive visual dysfunction. This rare genetic disorder is classified based on the phenotype, and the mutation in any one of more than 220 different genes are causal for this rare blinding condition. Retinitis pigmentosa is the most common subgroup of inherited retinal dystrophy characterized by reduced ability to perceive light and progressive loss of visual field. RP is genetically heterogeneous, and mutations in any one of over one hundred genes can cause the phenotype. RPE65 gene encodes all-trans-retinyl ester isomerase, an enzyme crucial to the retinoid cycle Autosomal recessive biallelic mutations in this gene lead to the inability to regenerate 11-cis-retinal, via 11-cis-retinol, in the retinal pigment epithelial cells RPE cells. This impairs the ability of RPE cells to respond to light, which disrupts the vis...

Linearity: The alternative approach for detecting non-linearity is to assess the residuals of an estimated regression line and test for whether positive and negative deviations are randomly distributed. It should be considered whether an estimated regression line passes through zero or not. The presence of linearity is a prerequisite for a high degree of trueness. Linearity refers to the relationship between measured and expected values over the analytical measurement range. Linearity may be considered in relation to the actual or relative analyte concentration. In case of relative analyte concentrations, a dilution series of a sample may be studied. The relative analyte concentration method is often used for immunoassays to measure whether the concentration decreases with dilution as expected. Dilution is usually carried out with the appropriate sample matrix. Analytical Range: The analytical range or reportable range is the analyte concentration range over which the measurement i...

The surfactants are chemical substance that is capable of lowering surface tension. The lung surfactants contain a complex mixture of phospholipids, neutral lipids, and specific proteins. The lung surfactants are essential for normal lung function as it reduces surface tension at the air-liquid interface of alveolar spaces.  Phosphatidylcholine is a major component of the surfactant comprising 90% of the lipids. Four specific surfactant proteins SP-A, SP-B, SP-C, SP-D. The synthesis and secretion of functional surfactants are confined to type II cells of the alveolar epithelium. The fundamental pathway for lung surfactant phospholipid synthesis, it's packaging into storage lamellar bodies (LB), secretion into the alveolar lining fluid and recycling back into ATII cells are well known. Bulk surfactant phospholipid synthesized at the ER is transported to LBs by a mechanism that may employ specific carrier proteins and/or traffic through the Golgi.  During the processes of s...

Question  Non-esterified fatty acids in the plasma a) circulate in an unbound state b) bind to lipoproteins and circulated c) bind to albumin and circulated d) bind to the fatty acid-binding protein and circulated Objective: The objective of the above question is to discuss - the function of non-esterified fatty acid and derivatives - the metabolism of non-esterified fatty acids. - the origin of non-esterified fatty acid in plasma - the role of non-esterified fatty acids in diabetes Answer and Explanation Fatty acids play critical roles in the energy metabolism of mammals. The bulk of fatty acids are stored in adipose tissues as triglycerides and mobilized during the energy-deprived state to tissues such as skeletal muscle, heart to fulfill their energy requirements. In addition, they are building blocks for phospholipids and other complex lipids which are a component of the cell membrane, a precursor for biologically active substances such as leukotrienes, pros...

Analytical Sensitivity: Analytical sensitivity is the ability of an analytical method to assess small variations of the concentration of analyte and they are often expressed as the slope of calibration curve. The analytical sensitivity depends on the ratio between the SD of calibration function (random error) and the slope. Analytical Specificity and Interference: The analytical specificity is the ability of an assay procedure to determine specifically the concentration of the target analyte in the presence of potentially interfering substances or factors in the sample matrix. The interference from hyperlipidemia, hemolysis, and bilirubin is generally concentration dependent and can be quantified as a function of the concentration of interfering compound. Diagnostic sensitivity The diagnostic/clinical sensitivity of an assay is the fraction of those with a specified disease that the assay correctly predicts. The sensitivity is also called the true positive rate. Simplifying the term, s...

Trueness and Accuracy The trueness of measurement can be defined as the closeness of agreement of between the average value obtained from large series of results of measurement and a true (actual) value. The difference between the average value and the true value is called the bias, which is inversely related to the trueness. Trueness can be evaluated by comparison of measurements by given method and a reference method. Such an evaluation may be carried out by parallel measurements of a set of test samples or by measurement of reference materials. The ISO has introduced the trueness expression as a replacement for the term “accuracy”. Accuracy is the closeness of the agreement between the result of measurement and a true concentration of the analyte. Accuracy is thus influenced by both bias and imprecision and in this way reflects the total error. Precision Precision may be defined as the clones of agreement between independent results of measurement obtained under specified conditions...