Basement membranes

Airway cross-sections have the nominal anatomy shown in Fig. 5.16. Airway surface liquid (AST), primarily composed of mucus gel and water, surrounds the airway lumen with a thickness thought to vary from 5 to 10 mm. AST lies on the apical surface of airway epithelial cells (mostly columnar ciliated epithelium). This layer of cells, roughly two to three cells thick in proximal airways and eventually thinning to a single cell thickness in distal airways, rests along a basement membrane on its basal surface. Connective tissue (collagen fibers, basement membranes, elastin, and water) lies between the basement membrane and airway smooth muscle. Edema occurs when the volume of water within the connective tissue increases considerably. Interspersed within the smooth muscle are respiratory supply vessels (capillaries, arteriovenous anastomoses), nerves, and lymphatic vessels. 

Basement membrane Layer of dense amorphous material on which cells as-... 

The basement membrane is a structure that supports overlying epithelial or endothelial cells. The primary fimction of the basement membrane is to anchor down the epithelium to its loose connective tissue underneath. This is achieved by cell-matrix adhesions through cell adhesion molecules. 

In biology, extracellular matrix (ECM) is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. ECM is the defining feature of connective tissue in animals. ECM includes the interstitial matrix and the basement membrane. 

The innermost layer of an artery, which consists of loose connective tissue covered by a monolayer of endothelium that resides on a basement membrane. In human arteries, the intima often contains resident smooth muscle cells even early in life. Atherosclerotic plaques form in the intima. 

Bartter s Syndrome Basal Activity Basal Ganglia Basement Membrane Basophils Bax... 

Martin, G.R. Timpl, R. (1987). Laminin and other basement membrane components. Ann. Rev. Cell. Biol. 3, 57-85. 

Type IV collagen, the best-characterized example of a coUagen with discontinuous triple helices, is an important component of basement membranes, where it forms a mesh-hke network. 

Certain proteoglycans (eg, heparan sulfate) are associated with the plasma membrane of cells, with their core proteins acmally spanning that membrane. In it they may act as receptors and may also participate in the mediation of cell growth and cell-cell communication. The attachment of cells to their substramm in cul-mre is mediated at least in part by heparan sulfate. This proteoglycan is also found in the basement membrane of the kidney along with type IV collagen and laminin... 

As noted above, the presence of Met(O) in proteins would go undetected after acid hydrolysis and subsequent amino acid analysis. Thus, since this method of hydrolysis is most commonly used, it is impossible to ascertain from the literature the abundance of Met(O) residues normally present in proteins. However, a number of studies have reported the presence of Met(O) residues in various proteins using one of the appropriate procedures described above. It has been found that Met(O) residues comprise 30% of the total Met in proteins isolated from bovine glomerular basement membranes and anterior lens . Other investigators have reported that the levels of Met(O) in proteins of the trabecular meshwork of human eyes increased with the age of the donor . The amount of Met(O) detected ranged from 15% (10 years old) to 55% (79 years old) of the total methionine content found in the tissue samples. Other studies have shown that in certain species of clams the proteins of the hinge ligament contain only Met(0) residues and no Met . In addition, it has also been reported that as much as 18% of the Met residues in pea seed proteins is in the form of Met(O) . Lastly, Met(O) residues have been found in... 

Amadori-type early glycosylation products (Brownlee et /., 1988). Protein that has been glycated in vitro is con-formationally altered. For example, the amount of early glycosylation products in vivo in diabetics, whether on haemoglobin (Hb) or basement membrane, increases when blood glucose levels are normalized by treatment. 

The lens is an avascular transparent tissue enveloped in the lens capsule, a basement membrane composed of type IV collagen (Harding and Crabbe, 1984). The single layer of epithelial cells under the anterior portion of the capsule divide throughout life, accumulate crystaUin... 

The vitreous is a transparent extracellular matrix occupying the space between the posterior lens and the retina and, in the majority of vertebrate species, constitutes the major f)art of the volume of the eye. Embryo-logically it can be considered as the basement membrane of the retina. It provides a mechanical support for surrounding tissues and acts as a shock absorber by virtue of its viscoelastic properties (Balzas and Delinger, 1984). Vitreous consists mainly of water (98%) and colloids (0.1%) with ions and low molecular weight solutes making up the remainder. It is not fully developed at birth, and changes in both volume and chemical composition occur postnatally. 

Diabetes continues to be a major cause of excessive morbidity, severe disability and premature death in Western populations. In developed countries, the cost of diabetes to society may be estimated to be as high as 5% of the total health costs, much of which relates to the chronic vascular complications of this disorder (Williams, 1991). The vascular lesion in diabetes consists of (1) microangiopathy, distinguished by thickening of capillary basement membranes resulting in increased vascular permeability, which is clinically manifested as diabetic retinopathy (Fig. 12.1a) and/or nephropathy (Fig. 12.1b), and (2) macroangiopathy (Fig. 12.2),... 

Vissers, M.C.M., Day, W.A. and Winterboum, C.C. (1985). Neutrophils adherent to a nonphagocytosable surface (glomerular basement membrane) produce oxidants only at the site of attachment. Blood 66, 161-166. 

GAP GTPase-activating protein GBM Glomerular basement membrane... 

Fig. 2.14 Cellular morphology of neuroepithelium chemosensory groove in lamellae of the African lungfish Protopterus annectens (Dipnoan) basal, receptor and supporting cells (CB, CRe and CS) MB basement membrane. Owen, x400 (from Derivot, 1984).

Maillard, J.-L. Favreau, C. Vergely, I. Reboud-Ravaux, M. Joyeau, R. Kobaiter, R. Wakselman, M. Protection of vascular basement membrane and microcirculation from elastase-induced damage with a fluorinated P-lactam derivative. Clin. Chim. Acta 1992, 213, 75-86. 

Glomerular diseases (e.g., anti-glomerular basement membrane disease, focal segmental glomerularsclerosis, IgA nephropathy, hemolytic uremic syndrome, systemic lupus erythematosus, Alport s syndrome, amyloidosis, membranous nephropathy, and Goodpasture s syndrome)... 

Malignant cells are divided into categories based on the cells of origin. Carcinomas arise from epithelial cells, whereas sarcomas arise from muscle or connective tissue. Adenocarcinomas arise from glandular tissue. Carcinoma in situ refers to cells limited to epithelial origin that have not yet invaded the basement membrane. 

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