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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Keratoconus is a disease that results in thinning and ectasia of the central cornea. Cultures of corneal stromal cells from patients with keratoconus were established and the synthesis of glycosaminoglycans compared with the synthesis of glycosaminoglycans by normal human corneal stromal cells in culture. Keratoconus and normal control cell cultures were incubated with sodium [(35)S]sulfate and [(3)H]glucosamine for 4 h. After incubation, the labeled glycosaminoglycans were isolated from the medium fractions and cells. Keratoconus and normal control cultures synthesized similar amounts of sulfated glycosaminoglycans independent of the age of donors and(or) the number of subcultures. In contrast to normal control cultures, most of the newly synthesized glycosaminoglycans produced by keratoconus cells were found in the growth medium and much less were in the cell layer. Treatment with glycosaminoglycan-degrading enzymes followed by paper chromatography showed that keratoconus cells, as normal control cells, produced hyaluronic acid and various sulfated glycosaminoglycans. The production of cell layer-related heparan sulfate was markedly reduced in keratoconus cultures. Because heparan sulfate has been shown to be associated with cell surfaces, the decreased heparan sulfate content could reflect changes at this location.
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PMID:The synthesis of glycosaminoglycans by cultures of corneal stromal cells from patients with keratoconus. 43 19

After a discussion of the role of synovial fluid as a joint lubricant, rheological measurements are described with both normal (healthy) synovial fluids and pathological ones. Shear stress and first normal stress difference are measured as a function of shear gradient to calculate the apparent shear viscosity eta 1 and the apparent normal viscosity psi 7 as well as an apparent shear modulus G'. It is found, that in case of diseased synoviae all rheological parameters deteriorate. Most significant changes are observed with the zero shear viscosity eta 0, the shear modulus G', and a characteristic time theta 1, which is the reciprocal of the critical shear rate Dc which determines the onset of shear thinning. The rheological deterioration of synovial fluids is explained in terms of solute structure, whereby a molecular mass of the backbone hyaluronic acid of at least 10(7) g.mol-1 is required for satisfactory function. A theory of the rheological performance of normal synovial fluid as well as its pathological deterioration is proposed.
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PMID:Rheology of synovial fluid. 366 97

Three lectins, wheat germ agglutinin (WGA), soybean agglutinin (SBA) and Ricinis communis agglutinin I (RCA), were used to study the basement membrane of developing chick lungs. Thinning of the basement membrane at the tips of newly formed bronchi was visualized with all three lectins, but was particularly evident using SBA. Control sections established the ability of the lectins to stain hyaluronic acid and chondroitin sulphate. Neuraminidase, bovine testes hyaluronidase and Streptomyces hyaluronidase removed some of the staining, but none were able to affect the staining of the basement membrane. Possible explanations for this are discussed in the text. Incorporation of [3H]thymidine is enhanced at the tips relative to the interbud area in stage-30 lungs, extending previous studies on stage-26 lungs. Evidence has been presented here which demonstrates that mechanisms of morphogenesis used in avian embryos are similar to those already elucidated in work on mammalian embryos.
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PMID:Basal laminar thinning in branching morphogenesis of the chick lung as demonstrated by lectin probes. 376 Jul 54

We evaluated the pathogenesis of skin thickening in three patients with acromegaly. Growth hormone levels were normal in one patient and were elevated in two patients. Skin biopsy specimens were obtained from the forearm. Hematoxylineosin staining showed slight epidermal thinning and, in two of the patients, a small increase in the number of fibroblasts. Selective stains for collagen, elastic, and reticular fibers disclosed normal connective tissue. The most striking abnormality was increased glycosaminoglycan deposition on the slides stained with colloidal iron. Glycosaminoglycan infiltration occurred mostly in the papillary and upper reticular dermis and was not directly related to the simultaneous growth hormone levels. Tissue digestion with specific enzymes identified hyaluronic acid, chondroitin-4- and 6-sulfate, and dermatan sulfate as the most prominent glycosaminoglycans in the dermis. The skin ultrastructure appeared to be preserved on electron microscopy. We conclude that cutaneous mucinoses is the main cause for the thickening of the skin in acromegaly.
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PMID:Histochemical characterization of the cutaneous involvement of acromegaly. 621 6

The disaccharide content of the chondroitinase-digestible glycosaminoglycans (GAGs) extracted from 6-mm skin punch biopsies from the atrophic and sclerotic skin of two patients with Werner's syndrome (WS) were determined using high-performance liquid chromatography after 1-phenyl-3-methyl-5-pyrazolone labelling. The total amount of main disaccharides was significantly decreased in the atrophic lesions of WS. In the atrophic forearm skin, the decrease in the main disaccharide unit of hyaluronic acid, delta Di-HA, and the increase in the ratio of the main disaccharide unit of dermatan sulphate, delta Di-4S, to delta Di-HA were significant vs. normal control (P < 0.01 and 0.05, respectively). The sclerotic skin showed an increase in delta Di-4S (DS) (P < 0.05) and a decrease in delta Di-HA (P < 0.02) compared with normal controls, as well as a significantly higher ratio of delta Di-4S (DS)/delta Di-HA compared with normal controls (P < 0.0002) and systemic sclerosis patients (SSc; P < 0.02). No other statistical difference was found in the amount of each main disaccharide unit between the sclerotic skin of WS and SSc. Histological examination revealed that the atrophic skin showed thinning of the dermis with a slight increase of fine collagen bundles, whereas the sclerotic skin demonstrated a thickened dermis with prominent deposition of fine collagen bundles in the deep dermis. In SSc, thickening of the whole dermis, composed of hyalinized or swollen collagen bundles, was found.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Disaccharide analysis of the skin glycosaminoglycans in patients with Werner's syndrome. 788 70

Semi-dilute (ca 2 g/dl) aqueous xanthan (mean molar mass ca 1 x 10(6) g/mol), when heated in the presence of 0.1 M NaCl to a temperature above the order<-->disorder transition temperature, forms highly viscoelastic solutions when returned to room temperature. The steady shear and dynamic rheological behaviour of these solutions discloses a weak gel structure, the viscosity of which is unusually sensitive to the rate of shear. In shear thinning behaviour these heat and salt treated xanthan solutions mimic the properties of the aqueous hyaluronic acid solutions widely used in viscosurgical techniques. The double stranded model of native xanthan is invoked to interpret the observed behaviour of heat and salt treated semi-dilute aqueous xanthan.
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PMID:Thermal treatment of semi-dilute aqueous xanthan solutions yields weak gels with properties resembling hyaluronic acid. 844 29

A boy presented at age 3.5 months with joint contractures, restlessness, and pain on handling. His skin was thickened and there were livid-red macular lesions over bony prominences. Infantile systemic hyalinosis (ISH) was diagnosed, a presumably autosomal recessive, progressive, and painful disorder of as yet unknown pathogenesis. Observation over three years confirmed the diagnosis as typical changes, such as nodules on both ears, pearly papules in the perinasal folds and on the neck, fleshy nodules in the perianal region, and gingival hypertrophy, developed. Skin lesions and painful joint contractures progressed in spite of intense physiotherapy, and at age 3, the child had marked motor disability. The central nervous system (CNS) appeared to be intact and the infant showed normal mental development. Radiologic findings included marked generalized osteopenia, osteolytic erosions in the metaphyses of the long bones, and cortical thinning. Electron microscopy of two skin biopsies demonstrated deposition of floccular amorphous substance that was abundant around, and appeared to originate from, small blood vessels in the dermis, partially interfering with collagen fiber formation. Lysosomal inclusions were not seen. Serum acid hyaluronidase activity was within the normal range, and the synthesis of hyaluronic acid and proteoglycans in cultured skin fibroblasts was similar to that of control cells. A younger sister presented at age two months with painful joint contractures and discrete livid-red macules over both malleoli, and showed a similar progression of the disorder over the first year of life. The diagnosis of ISH should be considered in infants and children presenting with painful joint contractures and skin lesions. The pathogenesis of this disabling and disfiguring disorder remains unclear. Our data confirm probable autosomal recessive inheritance, and do not support lysosomal storage, hyaluronidase deficiency, or a primary collagen disorder, but indicate that the amorphous material accumulating in the skin and articular soft tissues may originate from the blood circulation.
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PMID:Infantile systemic hyalinosis in siblings: clinical report, biochemical and ultrastructural findings, and review of the literature. 1129 73

Rheological blends of hyaluronic acid (HA) and hydroxypropylmethyl cellulose (HPMC) are attractive as injectable drug delivery vehicles given their shear thinning viscoelastic rheological properties and excellent biocompatibility. In this study, the rheological and water binding properties of HA-HPMC blends are investigated to optimize both the injectability and the drug release kinetics of polymer blends. The time required to release 75% of a bupivacaine payload was correlated with the overall polymer concentration of the blend and the water binding properties of the constituent polymers. This correlation enables the tuning of drug release kinetics over a range of several hours according to the total concentration and ratio of the polymers used in the blend. The injectability is also promoted by polymer blending; HPMC suppresses the high yield stress of HA solutions, whereas HA induces flow instabilities in the needle, which facilitate blend injection via plug flow. Consequently, significantly higher polymer concentrations can be injected as blends compared with that achievable with either of the polymers alone, extending the potential of these polymers for drug delivery.
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PMID:Rheological blends for drug delivery. I. Characterization in vitro. 1923 15

Rheological measurements were conducted on hyaluronic acid (HA)/bovine calf serum (BCS) solutions that can be used as analogues of synovial or periprosthetic fluid. The presence of HA affected profoundly the rheological properties of the solutions, with increased concentrations and higher molecular weight of HA leading to higher viscosities as well as more pronounced shear thinning in steady-shear flow. In dynamic oscillatory flow, the elastic character of the solutions became more pronounced and the cross-over frequency decreased upon increasing concentration and molecular weight of HA. The relevance of these results in the context of appropriate selection of a lubricating environment that mimics physiological conditions is discussed.
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PMID:Effect of concentration and molecular weight on the rheology of hyaluronic acid/bovine calf serum solutions. 1925 26

Using soft tissue fillers to correct postrhinoplasty deformities in the nose is appealing. Fillers are minimally invasive and can potentially help patients who are concerned with the financial expense, anesthetic risk, or downtime generally associated with a surgical intervention. A variety of filler materials are currently available and have been used for facial soft tissue augmentation. Of these, hyaluronic acid (HA) derivatives, calcium hydroxylapatite gel (CaHA), and silicone have most frequently been used for treating nasal deformities. While effective, silicone is known to cause severe granulomatous reactions in some patients and should be avoided. HA and CaHA are likely safer, but still may occasionally lead to complications such as infection, thinning of the skin envelope, and necrosis. Nasal injection technique must include sub-SMAS placement to eliminate visible or palpable nodularity. Restricting the use of fillers to the nasal dorsum and sidewalls minimizes complications because more adverse events occur after injections to the nasal tip and alae. We believe that HA and CaHA are acceptable for the treatment of postrhinoplasty deformities in carefully selected patients; however, patients who are treated must be followed closely for complications. The use of any soft tissue filler in the nose should always be approached with great caution and with a thorough consideration of a patient's individual circumstances.
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PMID:Soft tissue fillers in the nose. 1994 92


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