Category: Uncategorized
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Breaking barriers-Suppressing revolt While immunity is intrinsically designed to protect the self against foreign antigens, in the era of transplantation – allograft or xenograft, whole organ or stem cells – a deliberate attempt is made to suppress immune pathways that would reject the transplant. The barrier to tolerating the graft is broken by suppressing the…
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When self-defense becomes self-harm The Immune system, protects the human body from a range of adverse agents – infectious or non-infectious but is also equipped with a sophisticated range of options to prevent or obstruct injury to its own tissues by recognizing self as opposed to non-self. The failure of one or more mechanisms of…
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Immunity to usual and unusual offenders The Immune system’s structure and function unlike most organ systems in the body, is distributed (for surveillance) yet united in cross-talk within its components and receptivity to adverse stimuli. With a phenomenal capacity for explosive growth and diverse antigen recognition (commensurate with the severity of provocation) it closely resembles…
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What our genes foretell From Mendel’s 19th century research into inheritance in pea plants to groundbreaking discoveries supported by technology resulting in the Human Genome Project in the 21st century, within the last century-and-a-half, we have achieved a refined understanding of the impact of Genetics on human disease, inherited or acquired. As the anatomy of…
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The final bow: many ways to die Cell or tissue death follows irreversible injury due to a variety of etiologies. Apoptosis, morphologically a ‘falling out’ of a single cell from its surrounding tissues, is programmed and tightly regulated. In both physiological and pathological situations, its significance lies in leaving surrounding tissues undisturbed with absence of…
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Interruptio fluxus sanguinis: a weapon of mass tissue destruction The abrupt obstruction of arterial blood supply to target organs leads to coagulative tissue necrosis – infarction. Venous obstruction or compression can have similar consequences. Either event constitutes an emergency, especially in tissues which depend for vitality on oxygenation like the brain, heart and kidneys. The…
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Extravascular Blood loss or block of Intravascular blood flow Vessel wall damage due to injury or disease causes haemorrhage, the breach is easily sealed with a localized primary hemostatic plug of platelets reinforced by a sturdier secondary plug with fibrin derived from the activated coagulation cascade. In larger structural damage, with significant volume loss, emergency…
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Too much of a good thing: intracellular, extracellular, extravascular fluid excess Water is one of the key components of the milieu interior: when disbalanced in quantity and location, a diseased state is inevitable. Naturally confined in optimum quantities inside body cells and key to maintaining flow inside the vascular network, increased hydrostatic pressure (cardiac failure,…
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When the initiating injury is slow, immunity is slow to awaken A host of etiologies evoke chronic, not acute inflammation. Some infections, metabolic products, autoimmune reactions etc. are slow to be recognized by the immune system. Instead of the classical neutrophil response in acute inflammation, in chronic inflammation it is mononuclear and takes time. The…
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Chemical mediators: bane or boon? Accompanying the early vascular and cellular responses to inflammation, several pre-formed and newly synthesized chemical mediators flood the site of tissue injury. They originate from endothelial cells, immune cells and native stromal cells. At first, they amplify the inflammatory response to overcome the etiology and its tissue damage. Later, they…