Neutrophilic bacteria

An abscess begins by the combined action of inflammatory cells (such as neutrophils), bacteria, fibrin, and other inflammatory components. Within the abscess, oxygen tension is low, and anaerobic bacteria thrive. 

An abscess begins by the combined action of inflammatory cells (such as neutrophils), bacteria, fibrin, and other inflammatory mediators. Bacteria may release heparinases that cause local thrombosis and tissue necrosis or fibrinolysins, collagenases, or other enzymes that allow extension of the process into surrounding tissues. Neutrophils gathered in the abscess cavity die in 3 to 5 days, releasing lysosomal enzymes that liquefy the core of the abscess. A mature abscess may have a fibrinous capsule that isolates bacteria and the liquid core from antimicrobials and immunologic defenses. 

This electrophoretic technique involves the observation of motion of small particles in an electric field with a microscope (such as RB.Cs, neutrophils, bacteria etc.). The suspension is... 

Platinum—polyethyleneimine complexes prevent the division of bacteria, and are being tested as carriers in the treatment of cancer and vimses (445—447). Encapsulated PEIs containing nucleic acid bases activate the neutrophils in human blood (448). 

In the very early phases of the acute inflammatory response most of the cells invading the damaged area are polymorphonuclear neutrophils, also denoted as PMNs, which serve as initial line of defense and source of proinflammatory cytokines. These cells, which usually live for 4-5 days, circulate in the blood until they are attracted by chemokines into injured tissues. Whereas physical injury does not recruit many neutrophils, infections with bacteria or fungi elicit a striking neutrophil response. The characteristic pus of a bacterial abscess is composed mainly of apoptotic (apoptosis) and necrotic PMNs. Emigration of neutrophils from the blood starts with a process denoted as margination where neutrophils come to lie at the periphery of flowing blood cells and adhere to endothelial cells (Fig. 1). L-Selectin is expressed... 

Figure 2. (1) Neutrophils circulating passively in blood capillary. (2) Chemoattractants may be detected by the circulating neutrophils, by the endothelial cells lining the lumen, or both in order that the neutrophils become adhesive. This adhesion is mediated by selectins, a group of cell surface proteins. Neutrophils roll on the surface of the endothelial cells and then actively locomote seeking out spaces between the endothelial cells. (3) The adhesive neutrophils begin to squeeze between endothelial cells. (4) Cells move through the extracellular matrix towards the site of infection. Here adhesion is low and may not be necessary for locomotion. (5) At the site of infection, neutrophils become trapped by increased adhesion where they phagocytose bacteria and liberate the contents of their granules. After Lackie (1982,1986).

Superoxide is formed (reaction 1) in the red blood cell by the auto-oxidation of hemoglobin to methemo-globin (approximately 3% of hemoglobin in human red blood cells has been calculated to auto-oxidize per day) in other tissues, it is formed by the action of enzymes such as cytochrome P450 reductase and xanthine oxidase. When stimulated by contact with bacteria, neutrophils exhibit a respiratory burst (see below) and produce superoxide in a reaction catalyzed by NADPH oxidase (reaction 2). Superoxide spontaneously dismu-tates to form H2O2 and O2 however, the rate of this same reaction is speeded up tremendously by the action of the enzyme superoxide dismutase (reaction 3). Hydrogen peroxide is subject to a number of fates. The enzyme catalase, present in many types of cells, converts... 

Neutrophils are motile phagocytic cells that play a key role in acute inflammation. When bacteria enter tissues, a number of phenomena result that are collectively... 

Once having passed through the walls of small blood vessels, the neutrophils migrate toward the highest concentrations of the chemotactic factors, encounter the invading bacteria, and attempt to attack and destroy them. The neutrophils must be activated in order... 

The process of activation of neutrophils is essentially similar. They are activated, via specific receptors, by interaction with bacteria, binding of chemotactic factors, or antibody-antigen complexes. The resultant rise in intracellular Ca affects many processes in neutrophils, such as assembly of micrombules and the actin-myosin system. These processes are respectively involved in secretion of contents of granules and in motility, which enables neutrophils to seek out the invaders. The activated neutrophils are now ready to destroy the invaders by mechanisms that include production of active derivatives of oxygen. 

There have been recent studies on the importance of NO in modulating skin blood flow in both normal animals and in inflammatory models. Khan etiU. (1993), using laser-Doppler techniques, showed that the NOS inhibitor L-NAME inhibited rabbit ear blood flow. It was possible to do this chronically for up to 2 weeks using implanted osmotic pumps. Pons et id. (1993) also used laser Doppler to show that the vasodilator eflFect of LPS in rabbit skin, which mimics the efiect of Gram-negative bacteria, was likely to involve both i-NOS and IL-1. We have already discussed the damaging eflPects of neutrophils... 

Another important factor affecting microbial activity is pH. Microorganisms that can grow under acidic (pH < 4) or alkaline (pH > 10) conditions are termed acidophiles or alkalophiles, respectively. Most bacteria, however, are neutrophiles. Neutrophiles can tolerate pH levels between 5 and 9, but their optimum growth is observed in a relatively narrow range around neutrality, i.e., between... 

Neutrophils are the most abundant of the leukocytes and account for about 60% of the total number of white blood cells. These cells are usually the first to arrive at a site of injury or inflammation. Their primary function is to attack and destroy invading bacteria. In fact, bacterial infection is typically associated with pronounced neutrophilia (an increase in the number of circulating neutrophils). These leukocytes are also involved in removal of tissue debris and therefore play a role in the healing process. 

Lysosyme Serous cells, neutrophils, macrophages Gram positive bacteria Lyse gram positive bacteria via cleavage of peptidoglycan Decreased production after ozone exposure [121]... 

Defensins HD 1-6 HBD 1 and 2 Neutrophils (HD1-4) epithelial cells (HBD 1 and 2) macrophages Bacteria, mycobacteria, fungi, and some viruses Cidal activity and chemotaxis Upregulated in the lungs of smokers [36]... 

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