[...]... a chronic form can prevent healing from ever taking place; for example, chronic osteomyelitis following a compound fracture may persist for decades without resolution Persistence of an injurious agent such as a foreign body has much the same effect as infection in that it extends the period of inflammation and prevents the onset of healing Additionally they can act as a nidus for infection Foreign bodies... during platelet aggregation in haemostasis; chemotactic for monocyte/macrophages and neutrophils; mitogenic for mesodermal cells such as smooth muscle cells, microglia and fibroblasts; similar or identical factors produced by macrophages, endothelial cells, smooth muscle cells and transformed fibroblasts TGFβ (transforming growth factor β) Produced by transformed cells in culture; found in platelet α-granules,... proteins are inactivated by transformation of their physical form into beta-pleated sheets which are inert (silk is a beta-pleated sheet, which is why silk sutures are not metabolised in the human body) The human body has no enzymes for metabolising beta-pleated sheets, and amyloid, therefore, accumulates The material is waxy in appearance and reacts with iodine to form a blue-black pigment similar... elaboration of new proteins and is, therefore, energy dependent Such mechanisms require energy in the form of ATP, the synthesis of which is largely dependent upon available oxygen Consequently, it is often noticed that damaged tissue has a sudden requirement for increased amounts of oxygen: the so-called respiratory burst The proteins secreted at this time may be responsible for clearing away a lot of cell... limits the effects of IL-1 Source: Cotton D W K, Synopsis of general pathology for surgeons, Butterworth Heinemann, Oxford (1997) 14 CELLULAR INJURY CHAPTER TITLE RUNNING HEAD Under these circumstances free blood comes into contact with exposed collagen and with factors released from damaged cells, and clot formation occurs Clot formation is the solidification of blood outside the cardiovascular system or... contracts due to cross linking and the transformation of fibroblasts into myofibroblasts The clots thus form a framework for other cells to migrate over, and the entrapped cells, particularly macrophages and platelets, release various active agents that stimulate migration and replication of endothelial and epithelial cells They also stimulate each other to grow and transform (Table 1.2) This leads to a proliferation... Replication versus repair Cell loss due to some form of trauma results in healing if the trauma has not been so severe as to endanger the continued existence of the individual This healing can 13 1 1 GENERAL PATHOLOGY AND MICROBIOLOGY take two forms: the tissue can regenerate itself so that it is eventually much the same as it was before the trauma occurred, or it can form some sort of scar With time, scars... three-dimensional (3-D) structure for their function, and this 3-D structure is dependent upon various types of chemical bonds These bonds are disrupted by radiation, mostly by the intermediation of free radicals, and the proteins are then incapable of performing their structural or enzymatic duties Radiation-induced DNA damage includes: • • • strand breaks; base alterations; and formation of new cross links... growing from the base upwards, loses keratinocytes from the surface in the form of keratin flakes, and these are replaced by the division of cells in the basal layer Not all cells in the basal layer divide; some are specialised for attachment of the epidermis to the dermis Damage to this population of cells results in blister formation, but cell division is generally not affected and may even be increased... as proteins requires a very narrow pH and ionic range Carbon monoxide is a respiratory poison that binds strongly to haemoglobin, forming carboxyhaemoglobin and preventing the binding of oxygen Haemoglobin has an affinity for carbon monoxide some 200 times greater than that for oxygen The carboxyhaemoglobin complex is cherry pink, and people who have died of carbon monoxide poisoning classically have . sustainable forests PREFACE I am grateful to the publishers for the invitation to produce a second edition of Applied Basic Science for Basic Surgical Training. .