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A Hinek

Publications and source records attributed to A Hinek.

At least 55 records · Page 3Linked to original sources
PubMed1989

The elastin receptor shows structural and functional similarities to the 67-kDa tumor cell laminin receptor.

Laminin- and elastin-binding proteins were isolated by ligand affinity chromatography from plasma membranes of fetal bovine auricular chondroblasts and human A2058 melanoma cells. From both cell types, a 67-kDa protein was identified which bound to either elastin or laminin affinity resins. Structural and functional similarities between the elastin and laminin-binding proteins were suggested by 1) cross-reactivity between antibodies directed against the two proteins; 2) elution of the laminin receptor from laminin columns with soluble elastin peptides; and 3) modulation of substrate binding by galactoside sugars. In addition, extraction properties indicate that both receptors are peripheral membrane proteins whose association with the cell surface is mediated by their lectin properties. Mapping of the binding site on laminin suggests that the 67-kDa chondroblast receptor interacts with a hydrophobic elastin-like sequence in domain V of the B1 chain, and chemotaxis studies indicate that cell migration to elastin peptides and laminin involves the same receptor.

Amino Acid Sequence↗
PubMed1989

Elastin binds to a multifunctional 67-kilodalton peripheral membrane protein.

Elastin binding proteins from plasma membranes of elastin-producing cells were isolated by affinity chromatography on immobilized elastin peptides. Three proteins of 67, 61, and 55 kDa were released from the elastin resin by guanidine/detergent, soluble elastin peptides, synthetic peptide VGVAPG, or galactoside sugars, but not by synthetic RGD-containing peptide or sugars not related to galactose. All three proteins incorporated radiolabel upon extracellular iodination and contained [3H]leucine following metabolic labeling, confirming that each is a synthetic product of the cell. The 67-kDa protein could be released from the cell surface with lactose-containing buffers, whereas solubilization of the 61- and 55-kDa components required the presence of detergent. Although all three proteins were retained on elastin affinity columns, the 61- and 55-kDa components were retained only in the presence of 67-kDa protein, suggesting that the 67-kDa protein binds elastin and the 61- and 55-kDa proteins bind to the 67-kDa protein. We propose that the 67-, 61-, and 55-kDa proteins constitute an elastin-receptor complex that forms a transmembrane link between the extracellular matrix and the intracellular compartment.

Amino Acids↗
PubMed1989

Cartilage macromolecules and the calcification of cartilage matrix.

The calcification of cartilage matrix in endochondral bone formation occurs in an extracellular matrix composed of fibrils of type II collagen with which type X collagen is closely associated. Also present within this matrix are the large proteoglycans containing chondroitin sulfate which aggregate with hyaluronic acid. In addition, the matrix contains matrix vesicles containing alkaline phosphatase. There is probably a concentration of calcium as a result of its binding to the many chondroitin sulfate chains. At the time of calcification, these proteoglycans become focally concentrated in sites where mineral is deposited. This would result in an even greater focal concentration of calcium. Release of inorganic phosphate, as a result of the activity of alkaline phosphatase, can lead to the displacement of proteoglycan bound calcium and its precipitation. The C-propeptide of type II collagen becomes concentrated in the mineralizing sites, prior to which it is mainly associated with type II collagen fibrils and is present in dilated cisternae of the enlarged hypertrophic chondrocytes. The synthesis of type II collagen and the C-propeptide, together with alkaline phosphatase, are regulated by the vitamin D metabolites 24,25(OH)2 cholecalciferol and 1,25 (OH)2 cholecalciferol. At the time of calcification, type X collagen remains associated with type II collagen fibrils. It may play a role in preventing the initial calcification of these fibrils focusing mineral formation in focal interfibrillar sites. This process of calcification is clearly very complex, and involves different interacting matrix molecules and is carefully regulated at the cellular level.

Animals↗
PubMed1989

Neutrophils show chemotaxis to type IV collagen and its 7S domain and contain a 67 kD type IV collagen binding protein with lectin properties.

Neutrophils were found to demonstrate chemotactic responses to pepsinized human placental type IV collagen and its purified aminoterminal 7S domain. The maximal chemotactic responses occur at approximately 400 ng/ml and approximately 30 ng/ml of type IV collagen and 7S collagen, respectively, and are similar in magnitude to the chemotactic response of neutrophils to 10(-8) M FMLP. Human leukemic cells of the HL 60 line display chemotaxis to type IV collagen and 7S collagen only after they are differentiated along the neutrophilic pathway with dimethyl sulfoxide. When detergent extracts of neutrophils are applied to type IV collagen-Affi-Gel resin, a 67 kD protein is retained by the resin and is eluted with guanidine/octyl-beta-glucoside or lactose. This 67 kD polypeptide has an amino acid composition resembling the 67 kD component of the elastin receptor complex, displays immunologic cross-reactivity with antibody to the 67 kD component of the elastin receptor, and binds to elastin and laminin affinity resins. Neutrophil chemotaxis to type IV collagen and 7S collagen is selectively abolished by exposing the test neutrophils to lactose or elastin peptides. We conclude that neutrophils may migrate in vivo to proteolytic fragments of type IV collagen and that this response may be mediated by a lectin-like protein that is similar to the 67 kD component of the elastin receptor.

Amino Acids↗
PubMed1988

The elastin receptor: a galactoside-binding protein.

The elastin receptor complex contains a component of 67 kilodaltons that binds to a glycoconjugate affinity column containing beta-galactoside residues and is eluted from this column with lactose. This protein component is also released from the surface of cultured chondroblasts by incubation with lactose, and its association with immobilized elastin is inhibited by lactose. Since lactose also blocks elastic fiber formation by cultured chondroblasts, the galactoside-binding property of the elastin receptor is implicated in this process.

Animals↗
PubMed1988

Development of immunoreagents to ciliary zonules that react with protein components of elastic fiber microfibrils and with elastin-producing cells.

We describe the generation of a monoclonal antibody library to ocular zonule components and the characterization of three monoclonal antibodies: 1) one specific for microfibrillar associated glycoprotein (MAGP), a component of both ocular zonules and microfibrils of elastin fibers, 2) an antibody to an as yet unidentified 70,000 dalton antigen that is present in abundance in the extracellular matrix (ECM) of elastin-producing cells, and 3) an antibody reacting with the 67000 dalton subunit of the elastin receptor. The presence of antigenic determinants common to the ocular zonule and elastic fiber microfibrils suggests that zonules, which can be obtained in relatively pure form, can provide a valuable resource for characterizing proteins common to both microfibrillar structures.

Animals↗
PubMed1988

Kinetics of receptor-mediated binding of tropoelastin to ligament fibroblasts.

Soluble 125I-labeled tropoelastin bound to confluent cultures of bovine ligamentum nuchae fibroblasts and to fibroblast plasma membrane preparations in a time-dependent, saturable, and reversible manner. Scatchard analysis indicates that there are approximately 2 X 10(6) binding sites/cell with a binding efficiency (Kd) of 8 X 10(-9) M. Binding of tropoelastin to cells and membranes reached equilibrium by 90 min and was reversible with 50% of specifically bound material released by 40 min. Specific binding of tropoelastin to cells pre-treated with dilute trypsin solutions was reduced significantly when compared with controls. Four polypeptides of estimated molecular masses of 67, 61, 55, and 43 kDa were obtained from detergent extracts of plasma membranes by elution affinity chromatography on elastin-Affi-Gel. Our findings establish that elastin-specific binding proteins displaying characteristics of a true receptor are present on the surface of elastin-producing cells.

Animals↗
PubMed1988

The influence of vitamin D metabolites on the calcification of cartilage matrix and the C-propeptide of type II collagen (chondrocalcin).

The influence of vitamin D metabolites (at 1 X 10(-10) M) on the calcification of cartilage matrix (measured by 45Ca2+ uptake) and the C-propeptide of type II collagen (measured by radioimmunoassay) has been studied using organ cultures and chondrocytes isolated from growth plates of vitamin D-deficient and -sufficient 11-day-old rats. Vitamin D-deficient rats had reduced amounts of C-propeptide in their serum and freshly isolated growth plate chondrocytes. In all chondrocytes cultured from vitamin D-deficient animals, the C-propeptide content was maximal at 24 hr whereas calcification continued to increase for up to 72 hr. In organ and chondrocyte cultures of tissue from vitamin D-sufficient rats, both 1,25-dihydroxycholecalciferol (1,25(OH)2D3) and 24,25-dihydroxycholecalciferol (24,25(OH)2D3) were required for maximal stimulation of calcification and maximal increases in C-propeptide content. In these D-replete tissues, 24,25-(OH)2D3 had a less stimulatory effect on both calcification (organ and cell cultures) and C-propeptide (organ cultures only), while 1,25(OH)2D3 alone had no effect in cell cultures but an inhibitory effect in organ cultures. Studies of cells or tissue from growth plates of vitamin D-deficient rats demonstrated that 24,25(OH)2D3 alone produced maximal calcification and maximal increases in the C-propeptide content. 1,25(OH)2D3 generally had an inhibitory effect on both calcification and C-propeptide when used alone. In the presence of 1,25(OH)2D3, the stimulatory effect of 24,25(OH)2D3 was partly abrogated. Maximal stimulation of calcification and increases in C-propeptide by 24,25(OH)2D3 were observed at 1 X 10(-9) M and 1 X 10(-10) M. In none of these studies was there any effect on proteoglycan content.(ABSTRACT TRUNCATED AT 250 WORDS)

24,25-Dihydroxyvitamin D 3↗
PubMed1988

Defective bone formation by transplanted Hyp mouse bone cells into normal mice.

The hypophosphatemic (Hyp) mouse is a model for human X-linked hypophosphatemia (XLH). To test the hypothesis of an abnormal osteoblast function in XLH, periostea and osteoblasts isolated from normal and Hyp mice were transplanted im into normal and mutant mice. The thickness of the osteoid seams at the periphery of the bone nodules and the osteoid volume were measured in transplants as an index of bone formation. Impaired mineralization was evidenced in transplants of Hyp cells into Hyp mice by excessive osteoid thickness and volume compared with transplants of normal cells into normal mice. When normal cells were transplanted into mutant mice, the osteoid thickness and volume were markedly increased, demonstrating that the extracellular environment is critical for bone formation. In contrast, when Hyp cells were transplanted into normal mice, reduction, but not normalization, of the osteoid thickness and volume was observed. This abnormal bone formation supports the hypothesis of an osteoblast defect in the Hyp mouse.

Animals↗
PubMed1987

The calcification of cartilage matrix in chondrocyte culture: studies of the C-propeptide of type II collagen (chondrocalcin).

We have shown that when chondrocytes are isolated by collagenase digestion of hyaline cartilage from growth plate, nasal, and epiphyseal cartilages of bovine fetuses they rapidly elaborate an extracellular matrix in culture. Only growth plate chondrocytes can calcify this matrix as ascertained by incorporation of 45Ca2+, detection of mineral with von Kossa's stain and electron microscopy. There is an extremely close direct correlation between 45Ca2+ incorporation in the first 24 h of culture and the content of the C-propeptide of type II collagen, measured by radioimmunoassay, at the time of isolation and during culture. Moreover, growth plate cells have an increased intracellular content of the C-propeptide per deoxyribonucleic acid and, during culture, per hydroxyproline (as a measure of helical collagen) compared with nasal and epiphyseal chondrocytes. In growth plate chondrocytes 24,25-dihydroxycholecalciferol (24,25-[OH]2D3), but not 1,25-dihydroxycholecalciferol alone, stimulates the net synthesis of the C-propeptide and calcification; proteoglycan net synthesis is unaffected. Together, these metabolites of vitamin D further stimulate C-propeptide net synthesis but do not further increase calcification stimulated by 24,25-(OH)2D3. These observations further demonstrate the close correlation between the C-propeptide of type II collagen and the calcification of cartilage matrix.

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Effect of pollen extract on the development of experimental atherosclerosis in rabbits.

Our previous studies have shown that the pollen extract, Cernitin, reveals lipid-lowering properties in animals and humans. The present study was designed to investigate the influence of Cernitin on the development of experimental atherosclerosis in rabbits over a period of 12 weeks. Forty male mongrel rabbits were divided into 4 equal groups: (1) controls, (2) animals receiving high-fat diet (HFD) containing cholesterol and coconut oil, (3) HFD + pollen extract, and (4) HFD + clofibrate. The most pronounced reduction in lipid metabolism and in the severity of plaque formation occurred after the pollen extract had been applied. The total cholesterol content in serum and liver homogenate was depressed by 67% and 45%, respectively, while the serum HDL cholesterol and alpha-lipoproteins level was increased by 19% and from 7.73% to 21.73% respectively. The cytochrome P-450 content in the liver microsomes was elevated by 98% (nmol/g liver). Atherosclerotic plaque intensity at 12 weeks, measured planimetrically, averaged 85.5% in HFD-fed animals vs 33.7% in pollen extract-treated rabbits. These findings suggest that Cernitin, in addition to significantly lowering serum lipid levels in rabbits on an experimental diet, may modify lipid deposition in major arteries.

Animals↗
PubMed1986

The influence of inosine on adriamycin-induced cardiomyopathy in rats.

The effect of inosine on adriamycin-induced cardiomyopathy was studied. Total adriamycin (ADR) dose of 25 mg/kg i.p. injected in 15 equal partial doses 3 times a week for five following weeks evoked fully developed cardiomyopathy in rats. Inosine 200 mg/kg i.p. injected 5 times a week parallel to ADR diminished ADR cardiotoxicity evaluated by electrocardiographic recordings and histopathological examination. Moreover lower cytostatic toxicity was observed as judged by less-expressed leucopenia and lower SGOT activities in inosine treated animals.

Animals↗
PubMed1985

The protective effect of pollen extracts against allyl alcohol damage of the liver.

In male Wistar rats the hepatoprotective effect of pollen extracts (Cernitins) agains. orally introduced 1% allyl alcohol (0.4 ml per 100 g body weight) was investigated Cernitins were applied orally at 0.6, 24 and 30 h after allyl alcohol administration. After 48 h an autopsy was performed and blood was collected for biochemical tests. Liver damage was evaluated by measurement of aminotransferases (AspAT, AlAT) and alkaline phosphatase activity, total bilirubin level in the blood serum as well as by histological examination of the livers. Cernitins significantly reduced the serum enzymes elevations induced by allyl alcohol. The hepatoprotective properties of Cernitins were confirmed by histopathological studies.

1-Propanol↗
PubMed1985

The effect of Cernitins on galactosamine-induced hepatic injury in rat.

Cernitins correspond to microbiologically fermented pollen extract. Cernitin T60 contains mainly water soluble, while Cernitin GBX mainly fat soluble substances. The aim of the present work was to examine the effect of Cernitins on the d-galactosamine-induced liver damage in rat. It has been shown, that galactosamine administration to rat resembles viral hepatitis both biochemically and histologically. Our studies proved, that Cernitin T60 given orally or intraperitoneally inhibited or counteracted the elevation of amino transferases activity and the inflammatory process, necrosis and steatosis of the liver cells. The protective effect of Cernitin GBX on the liver parenchyma was only slightly expressed. It is concluded, that application of pollen extracts in patients with liver diseases should be considered.

Animals↗
PubMed1984

The effect of agarose and dexamethasone on the nature and production of extracellular matrix components by elastic cartilage chondrocytes.

Chondrocytes isolated enzymatically from rabbit ear cartilage, were cultivated in vitro in the presence of 2% agarose or 0.1 mumol/l dexamethasone. Freshly-isolated chondrocytes suspended in either Eagle's medium or 2% agarose were auto-transplanted intramuscularly. Samples were then examined by light microscopy and transmission electron microscopy. The cells cultivated in vitro rapidly formed confluent multiple overlapping layers filled with a loose matrix consisting of single collagen fibres, proteoglycans and scarce elastic fibres. The number and maturity of the elastic fibres increased substantially after dexamethasone was added. The chondrocytes in intramuscular transplants produced a larger amount of intercellular matrix with many elastic fibres than those cultured in vitro. Addition of agarose to in vitro and in vivo systems selectively suppressed the elastin production but did not diminish the production of elastic fibre microfibrils and other matrix components. This made cultures and transplants of elastic chondrocytes resemble rather hyaline cartilage than the original tissue. It seems that the lack of elastin in the matrix does not result simply from inhibition of elastin secretion or increased elastolysis. It may be related to a reversible change of genetic expression of elastic cartilage chondrocytes under the influence of agarose.

Animals↗
PubMed1981

Elastin formation in heterotopic transplants of isolated arterial smooth muscle cells.

Smooth muscle cells were isolated from the aorta of 5 day old rats by collagenase digestion and injected intramuscularly into animals of the same strain, where the cells reconstituted an elastic tissue with many similarities to that found in the media of the intact aortic wall. The transplants consisted of partly aligned smooth muscle cells surrounded by an extracellular matrix of microfibrils, elastic fibers, bundles of collagen fibrils, and small granules believed to represent proteoglycans. The production of extracellular matrix was much more efficient than in cultures of arterial smooth muscle cells. This cell transplantation system may be valuable in elucidating the mechanisms of normal growth and development of the arterial wall as well as the pathogenesis of various pathological processes.

Animals↗