Thickening, cell membrane

Membrane Thickening. Cell envelopes are usually neglected in discussions of skin penetration, although Matoltsy (65) wrote, the cell membrane can be looked on as the specific protective element of each comified cell, since it is much more resistant than the epidermal keratin. He also observed that loss of barrier function is maximum when SC is treated with reagents that aflEect membranes (66). 

The histologic findings in asthma consist of massive epithelial shedding, hyperplasia of smooth muscle fibers, mucus glands and goblet cells, basement membrane thickening (Brewster etal., 1990), and eosinophil infiltra-... 

In general, seminiferous tubules involved by IGCNU rarely show spermatogenesis and often have decreased tubular diameter with thickening of their peritubular basement membrane. IGCNU cells are basally located... 

Inhibition of vascular smooth muscle cell (VSMC) prolifoation with consequent reduction of thickening of the vascular wall (intima-media thickness (IMT) Prevention of altered vascular blood flow, extracellular matrix deposition, basement membrane thickening, and neovascularization during diabetes and insulin resistance Reduction of collagen accumulation in type 11 diabetic rat model... 

Other non-specific abnormalities in three out of ten cases of Crocker and Parker (1958) included swelling and dilation of tubular cells and basal membrane thickening of glomeruli. In spite of such changes, evidence of significant functional impairment was not found. The intravenous pyelograms which were performed were normal. 

Fig. 6.3 Adult neuromuscular junction with the three cells that constitute the synapse the motor neuron (i.e. nerve terminal), muscle fibre and Schwann cell. The motor neuron from the ventral horn of the spinal cord innervates the muscle. Each fibre receives only one synapse. The motor nerve loses its myelin to terminate on the muscle fibre. The nerve terminal, covered by Schwann cell, has vesicles clustered about the membrane thickenings, which are the active zones, towards its synaptic side and mitochondria and microtubules towards its other side. A synaptic gutter, made up of primary and many secondary clefts, separates the nerve from the muscle. The muscle surface is cormgated, and dense areas on the shoulders of each fold contain acetylcholine receptors. The sodium channels are present at the clefts and throughout the musele membrane (from Martyn 2005, p 863 copyright Elsevier)...

Asthma is characterized by variable damage to the bronchial epithelium and increased numbers of airway mucosal and submucosal inflammatory cells, including eosinophils, mast cells, and T lymphocytes (19-21). Other prominent features of asthma include hypertrophy and hyperplasia of airway smooth muscle, basement membrane thickening, mucosal edema and excessive secretion of mucus, all of which contribute to airway narrowing (22). 

The gene defective in cystic fibrosis codes for CFTR (cystic fibrosis transmembrane condnctance regulator), a membrane protein that pumps CP out of cells. If this CP pump is defective, CP ions remain in cells, which then take up water from the surrounding mucus by osmosis. The mucus thickens and accumulates in various organs, including the lungs, where its presence favors infections such as pneumonia. Left untreated, children with cystic fibrosis seldom survive past the age of 5 years. 

Natural biological membranes consist of lipid bilayers, which typically comprise a complex mixture of phospholipids and sterol, along with embedded or surface associated proteins. The sterol cholesterol is an important component of animal cell membranes, which may consist of up to 50 mol% cholesterol. As cholesterol can significantly modify the bilayer physical properties, such as acyl-chain orientational order, model membranes containing cholesterol have been studied extensively. Spectroscopic and diffraction experiments reveal that cholesterol in a lipid-crystalline bilayer increases the orientational order of the lipid acyl-chains without substantially restricting the mobility of the lipid molecules. Cholesterol thickens a liquid-crystalline bilayer and increases the packing density of lipid acyl-chains in the plane of the bilayer in a way that has been referred to as a condensing effect. 

The pleura are connective tissue membranes composed of matrix, mesotheli-al cells, and fibroblasts. There are two types of pleural responses benign responses, such as thickening of the matrix, formation of plaques (which may calcify) or effusions, and fluid accumulation in the interpleural spaces between the visceral and parietal pleurae and neoplastic disease, or the malignancy known as mesothelioma. 

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