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Process Affinity Chromatography
Published in Juan A. Asenjo, Separation Processes in Biotechnology, 2020
Tissue-type plasminogen activator (tPA) is a glycoenzyme that converts plasminogen to plasmin, which degrades the fibrin network associated with blood clots. Plasminogen activator from genetically manipulated human Bowes melanoma cells was purified in two successive charomatographic steps. The first column, zinc chelate-Sepharose CL-4B, was chosen because it is very effective in concentrating tPA from the harvest medium, whereas the second column, lysine-Sepharose CL-4B, was chosen because of its biospecificity for tPA. These adsorbents have also been selected among others because they can be autoclaved and thus the operation performed aseptically. A batch of 45 L of filtered harvest medium was loaded on the zinc chelate column (0.9 L), the unbound material was washed off, and adsorbed tPA was eluted in a buffer containing 0.05 M immidazole and directly applied to the lysine column (0.18 L). After washing the affinity adsorbent to remove unbound material, tPA was eluted in a buffer containing 0.5 M L-arginine. A total of 360 L of medium could be processed in eight cycles (Dodd et al., 1982).
Central nervous system
Published in David A Lisle, Imaging for Students, 2012
Most acute ischaemic strokes are due to acute thromboembolic occlusion of cerebral arteries. Haemorrhagic infarction refers to haemorrhage into a region of infarcted brain. Haemorrhagic infarction may occur following clearing of an arterial occlusion with restoration of blood flow to damaged brain. Acute arterial occlusion produces a central region of infarcted brain tissue with a surrounding zone of hypoxic tissue. This hypoxic tissue is potentially salvageable and is termed the ischaemic penumbra. Intravenous infusion of thrombolytic agents such as tissue plasminogen activator (tPA) within the first 3 to 4.5 hours following stroke onset may salvage reversibly damaged brain tissue in the ischaemic penumbra. Thrombolysis with intravenous tPA is associated with improved neurological function in up to one in three patients. Risk of intracerebral haemorrhage producing an adverse outcome is about one in 30. tPA is contraindicated in the presence of haemorrhage.
Careers in Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Heart attacks occur when a blood clot enters one of the coronary arteries and cuts off blood flow to a portion of the heart. If the artery is not reopened quickly, severe damage to the heart can occur. Doctors can now prescribe a genetically engineered drug called tissue plasminogen activator (TPA) that travels to the blood clot and breaks it up within minutes, restoring blood flow to the heart and lessening the chance of permanent damage.
Task, usability, and error analyses of ambulance-based telemedicine for stroke care
Published in IISE Transactions on Healthcare Systems Engineering, 2021
Hunter Rogers, Kapil Chalil Madathil, Anjali Joseph, Nathan McNeese, Christine Holmstedt, Richard Holden, James T. McElligott
Neurologist awareness is of paramount importance for this system to be effective. The neurologist must gather information from the patient and paramedic to maintain an awareness of patient status and develop a diagnosis and care plan. Development and maintenance of this awareness is necessary specifically for ischemic strokes, which account for 87% of all strokes, as the treatment protocol, referred to as tissue plasminogen activator (tPA) (Benjamin et al., 2017), has multiple conditions and contraindications affecting its use, the most common being that it must be administered within 0 to 4.5h of stroke symptom onset (Powers et al., 2018). As such, awareness of the time from the symptom onset is critical. Time is not the only factor that neurologists must be aware of; a hemorrhage, high blood pressure or the use of blood thinners all prohibit a patient from receiving tPA (Fugate & Rabinstein, 2015). In addition, clinicians must rule out mimics for strokes such as low blood sugar or seizures. .
Preparation and characterization of tissue plasminogen activator-loaded liposomes
Published in Soft Materials, 2022
Katsiaryna Dubatouka, Vladimir Agabekov
Liposomes are small, nontoxic, biodegradable and biocompatible self-organized spherical vesicles consisting of one or more phospholipid bilayers that closely resemble the structure of cell membranes.[1] Due to the amphiphilic character of lipids, hydrophobic and hydrophilic substances, such as drugs, proteins, enzymes, and nucleotides can be encapsulated into liposomes that can be used in medicine as drug delivery systems.[2,3] Alteplase (tissue plasminogen activator, tPA) is a serine protease with a molecular weight of ~68 kDa, which is used for treating thromboembolic conditions. Tissue plasminogen activator converts plasminogen into fibrinolytic enzyme plasmin that then degrades fibrin, leading to clot dissolution.[4,5] It is known that tPA acts only on plasminogen associated with a thrombus, has fibrin-specificity and low immunogenicity, making it possible to reduce the dosage of the drug and use it for the treatment of acute myocardial infarction effectively.[6] At the same time, there are some limitations in the use of TPA for the treatment of thrombosis: a narrow therapeutic window, a short half-life (4–6 minutes) and poor penetration into large blood clots.[7] Moreover, tissue plasminogen activator is very sensitive to changes in pH, ionic strength, temperature, the presence of detergents, metal ions and non-aqueous solvents, which leads to denaturation, aggregation, precipitation, nonspecific adsorption and decrease in the biological activity of the substance.[8] The incorporation of tPA into liposomes protects the drug against chemical and immunological breakdown in the circulation, maintains its activity and provides prolonged effect.[4,6,9–11]