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Northern Blot Protocol

The northern blot is a technique used to study gene expression via mRNA transcripts. The northern blot was named after the southern blot, which was developed to study DNA. The two techniques are the same except that the northern blot is used to detect RNA while the southern blot is used to detect DNA. The northern blot protocol, in brief, involves gel electrophoresis to separate mRNA by size, a blotting step to transfer the separated mRNA to a membrane, and a probe hybridization step to identify the mRNA sequence of interest. Even with the advent of powerful RNA analysis techniques such as RT-qPCR and sequencing, the northern blot is still useful for comparing gene expression between samples. The northern blot protocol is relatively inexpensive, and makes it easy to visualize the results on a single membrane.  

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Immobilized enzymes

 Enzymes are the catalysts for biochemical reactions. As such, they speed up the transition from reactants to products without being consumed in the process. Multiple enzymes can be found in every cell, from bacteria up through to humans. We as humans have found ways to exploit enzymes to produce food products, fuel, pharmaceutical products, biotechnological tools, sensors, and much more. The potential uses for enzymes are seemingly limitless. The creation of solid support structures with immobilized enzymes has improved our ability to reuse enzymes in a controlled manner for a variety of applications. Immobilized enzymes can be reused multiple times before their efficacy is lost. This allows them to be an affordable part of industrial processes.

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Single Domain Antibody

Until this point we have been thinking about antibodies as one of the five classes, IgG, IgE, IgD, IgA, or IgM. The basic unit of each antibody class is a Y structure, where the base of the Y is known as the Fc region and the arms are the Fab region. The entire IgG antibody is composed of four polypeptide chains (two heavy and two light). The Fc region is composed only of heavy chain, and the variable Fab region is built with heavy chain and light chain. The Fab region is where all of the antigen-binding  occurs because the paratope, or antigen recognition site is located at the tip of each of the two arms of the Y. A single domain antibody paratope is made solely of a single heavy chain.

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Classes of Antibodies

The structure of the most commonly known antibody class (IgG) was a mystery until 1959, when it was elucidated by Edelman and Porter . The duo approached the question from two very different directions, but they were both awarded the 1972 Nobel Prize in Physiology or Medicine for their groundbreaking work. Gerald Edelman said that he was, “fascinated by the specificity of antigen recognition by antibodies,” and hoped that, “by doing the primary structure of antibody molecules, the basis of their specificity would be revealed.” Indeed, it was.

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Pharmaceutical validation

Pharmaceutical validation is important to the manufacturing process to ensure product consistency and safety. It involves regulation of all raw materials and production procedures as well as testing of final product. The general rule of thumb is to follow good manufacturing practice (GMP). This demands that all protocols be up to date and followed by trained personnel. It also requires that equipment be well-maintained and inspected. In the case of clean-room usage the clean room needs to be verified.

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The step-by-step process of protein purification

Protein purification is the processes of isolating a protein of interest from its environment. In other words, from the other natural molecules surrounding the proteins in the natural niche in a host organism, or from a cell culture grown in a laboratory. Our protein purification handbook  explains that there are several available techniques and many options to consider, but the general procedure is the same. 

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Different types of Immunoassays

An immunoassay capitalizes on the specificity of the antibody-antigen binding found naturally in the immune system. The assay can be used to identify the presence of pathogens in a clinical sample, or it can be used to measure the amount of a target biomolecule. If the goal of the immunoassay is to isolate a specific molecule then a separation system is needed. When the isolation is achieved by magnetic separation using a magnetic particle it is called a magneto-actuated immunoassay. The most common particle used in these assays is made of a core of magnetite that is coated with a biologically compatible material, and chemically modified by the attachment of antibodies. However, before designing a magnetic particle for an immunoassay one must decide which type of immunoassay best fits the goals of the experiment.

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ICH guidelines for stability testing of new drug substances and products

We have come a long way from the days of blood letting, trephination, and snake oil salesmen peddling cure-all tonics. The oversight and regulation of organizations such as the European Medicines Agency and the Federal Drug Administration (FDA) have significantly improved the quality and safety of our medical and pharmaceutical products. Of course, our medical understanding has deepened dramatically, our science has become more sophisticated, and we have developed tools to perform large scale drug discovery and screening. With this deeper understanding of chemistry and drug development we have realized the importance of preserving the chemical molecules via proper storage conditions.

The ICH guidelines for stability lay out the requirements for identifying and maintaining drug efficacy by understanding the pathways of degradation. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) was founded in 1990. The European Commission, FDA from the USA, and the Ministry of Health, Labour, and Welfare (MHLW), which later became the Pharmaceuticals and Medical Devices Agency (PMDA) in Japan are all founding members. Since that time, many other regulatory authorities from around the world have joined the ICH. The stated mission of the ICH is to “achieve greater harmonisation worldwide to ensure that safe, effective, and high quality medicines are developed and registered in the most resource-efficient manner.”

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Superparamagnetic iron-oxide nanoparticles (SPION)-enhanced MRI imaging

Superparamagnetism is a type of magnetism that lies between that of a permanent magnet and a paramagnet. Recall that a permanent magnet is always magnetic at temperatures below its Curie Temperature even in zero applied magnetic field, whereas a paramagnet is not magnetic at zero applied field but can become magnetic when an external magnetic field is applied. The potential for a paramagnet to be induced to have magnetization is called magnetic susceptibility. A superparamagnet behaves similarly to a paramagnet. The “super” means that it has a higher magnetic susceptibility than a regular paramagnet when a magnetic field is applied. Superparamagnets are typically made of iron oxide or other ferrous materials, and they are extremely small, on the order of 10-100 nanometers.

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Protein expression and purification

Proteins are constantly being created by the cellular machinery of living organisms. This article will first summarize the process as it occurs in a natural organism, and then discuss how protein expression and purification occurs in a laboratory setting for the generation of recombinant proteins.

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