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S Ayad

Publications and source records attributed to S Ayad.

At least 55 records · Page 3Linked to original sources
PubMed1987

Partial characterization of type X collagen from bovine growth-plate cartilage. Evidence that type X collagen is processed in vivo.

Sequential extraction of bovine growth-plate cartilage with 4 M guanidinium chloride and pepsin was used to identify the intact and pepsinized forms respectively of type X collagen. This collagen occurs predominantly as the processed [alpha 1(X)]3 form in vivo, although the procollagen [pro alpha 1(X)]3 form can also be detected. The bovine pro alpha 1(X) and alpha 1(X) chains have Mr values identical to the corresponding chick species (Mr 59,000 and 49,000). However, the pepsinized alpha 1(X)p chains (Mr 47,000) are larger than those of the chick (Mr 45,000), and the bovine collagen type X is further distinguished by being disulphide-bonded within the triple-helical domain.

Animals↗
PubMed1987

Incidence of antibodies to native and denatured cartilage collagens (types II, IX, and XI) and to type I collagen in rheumatoid arthritis.

The frequencies of antibodies to the cartilage type IX and XI collagens and to type I collagen were determined in 188 patients with rheumatoid arthritis, of whom 76 were positive for antibodies to native type II collagen. A higher proportion of patients with antibodies to native type II collagen had antibodies to these other collagens, but about one third of patients without antibodies to native type II collagen had antibodies to one or more denatured collagens. The patterns of antibodies present in individual sera suggested that there was a selective response to the collagens in an individual patient. The incidence of patients having antibodies to these native and denatured collagens in a random group of patients with rheumatoid arthritis was calculated.

Antibodies↗
PubMed1986

Type VI collagen and glycoprotein MFPI are distinct components of the extracellular matrix.

Two collagenous glycoproteins, Mr 140,000 and Mr 150,000, are synthesized and secreted into the medium of cultured fibroblasts. The glycoprotein of Mr 140,000 is identical with the 140K(VI) component of type VI collagen by both immunological and physicochemical criteria. The glycoprotein of Mr 150,000 is immunologically distinct and exhibits the physicochemical characteristics of the putative elastic microfibrillar glycoprotein MFPI.

Animals↗
PubMed1985

Isolation from bovine elastic tissues of collagen type VI and characterization of its form in vivo.

Foetal-bovine nuchal ligament and aorta, together with adult-bovine aorta and pregnant uterus, were extracted under dissociative conditions in the absence and in the presence of a reducing agent. A collagenous glycoprotein of Mr 140000 [designated component 140K(VI)], identified in these extracts as the major periodate/Schiff-positive component, was shown to be related to collagen type VI. Digestion of non-reduced extracts with pepsin yielded periodate/Schiff-positive peptides that, on the basis of their electrophoretic mobilities, amino acid analyses and peptide 'maps', were identical with type VI collagen fragments prepared by standard procedures. It is concluded that collagen type VI occurs in vivo as molecule comprising three chains of Mr 140000 in which the helical domains account for about one-third of each polypeptide. Biosynthetic experiments with nuchal-ligament fibroblasts in culture demonstrated that a bacterial-collagenase-sensitive [3H]fucose-labelled glycoprotein, Mr 140000, was immunoprecipitated from culture medium by a specific antibody to the pepsin-derived form of collagen type VI. This result suggests that the collagenous polypeptides [140K(VI) components] represent the biosynthetic precursors of type VI collagen that do not undergo processing to smaller species before deposition in the extracellular matrix. Analyses of 5M-guanidinium chloride extracts of tissues with markedly different elastin contents and at different stages of development suggested that there was no relationship between collagen type VI and elastic-fibre microfibrils, a conclusion supported by the observation that the immunoprecipitated glycoprotein, Mr 140000, was distinct from the glycoprotein MFPI, Mr 150000, believed to be a constituent of these microfibrils [Sear, Grant & Jackson (1981) Biochem. J. 194, 587-598].

Amino Acids↗
PubMed1985

The morphological features of bovine meshwork cells in vitro and their synthetic activities.

The morphological characteristics of 3rd-passage cultured bovine meshwork cells were investigated, as were some of their synthetic activities. Growing meshwork cells had the ultrastructural characteristics of metabolically active cells whereas postconfluent cells formed gap junctions at their lateral borders and were closer in their fine structure to meshwork cells in vivo. The incorporation of 3H proline and 3H glucosamine was significantly greater in growing than postconfluent cultures. The normal bovine outflow system was rich in type I collagen but type V collagen and fibronectin was also evident. The 3rd-passage cells were shown to synthesize type I collagen, type V collagen and fibronectin. However, ultrastructural studies of the extracellular matrix which was produced in vitro demonstrated the presence of small fibrils with no distinctive banding pattern, unlike the larger collagen fibrils with a 640 A banding pattern seen in vivo.

Animals↗
PubMed1984

Collagen heterogeneity and quantification in developing bovine nuchal ligament.

The collagenous components were investigated in peptic digests of developing bovine nuchal ligament. Types I and III collagen were the major species isolated, but the presence of types IV, V and VI was also shown. Changes in the pepsin-susceptibility of nuchal ligament during foetal development were observed. CNBr-cleavage peptide analysis indicated that type I collagen became cross-linked rapidly, as evidenced by the lack of alpha 1(I)CB6. At present it is not clear if this decrease in pepsin-susceptibility is due to cross-linking of collagen, to increased deposition of elastin, or to both. Quantification of collagen types I and III was shown to depend on the method used. When pepsin-solubilized material was examined an apparent increase in type III collagen with respect to foetal age was observed, whereas when CNBr digests of intact ligament were examined a relatively constant amount of type III collagen (approx. 24%) was found. The constant amount of type III collagen observed during foetal development changed at birth and increased in mature nuchal ligament to represent approx. 45% of the total collagen.

Amino Acids↗
PubMed1984

A collagenous glycoprotein found in dissociative extracts of foetal bovine nuchal ligament. Evidence for a relationship with type VI collagen.

A collagenous glycoprotein (Mr 140000) was isolated from dissociative extracts of foetal bovine nuchal ligament and purified by a combination of ion-exchange and gel-filtration chromatography. This glycoprotein (designated MFPI) exists as a large-Mr disulphide-bonded aggregate in the absence of a reducing agent. The purified glycoprotein was shown to contain about 6% (w/w) carbohydrate, mostly as galactose, glucose and mannose. Amino acid analysis showed the presence of hydroxyproline and hydroxylysine, indicative of its collagenous nature. The collagenous nature of this glycoprotein was further investigated by enzyme digestion. Pepsin digestion produced three major fragments, which were identical with peptides of type VI collagen. Bacterial-collagenase digestion of the unreduced glycoprotein also produced several discrete peptides. However, reduction of the glycoprotein before bacterial-collagenase digestion resulted in the degradation of these discrete peptides. Glycoprotein MFPI extracted in dissociative conditions appears to be a larger-Mr form of type VI collagen, believed to originate from microfibrillar components in the intact tissue.

Amino Acids↗
PubMed1984

A new look at vitreous-humour collagen.

The collagens of bovine vitreous-humour and nasal-septum cartilage have been extracted, fractionated and compared. Both tissues show the same heterogeneity of collagen types, consisting of type II, 1 alpha, 2 alpha, 3 alpha and C-PS collagens. The type II collagen of the vitreous humour was significantly more hydroxylated both in the lysine and proline residues than was that of cartilage. C-PS1 collagen, together with higher-Mr forms were present in the vitreous humour, but the higher-Mr forms were not seen in cartilage. Both C-PS1 and C-PS2 were present in vitreous humour and cartilage, but vitreous humour contained three times more of these collagens than did cartilage. Despite the difference in amount, the molar ratio C-PS1/C-PS2 was approx. 1 in both tissues, suggesting that they are components of a larger molecule. The 1 alpha, 2 alpha, 3 alpha collagens were present in the same concentration in both tissues. These three chains co-precipitated on dialysis against phosphate-buffered saline, pH 7.2, in a manner analogous to type V collagen.

Amino Acids↗
PubMed1983

Localisation of collagen types and fibronectin in cartilage by immunofluorescence.

Collagens type I, II, III, IV, and V and the minor cartilage collagens, 1 alpha 2 alpha 3 alpha, C-PS 1, and C-PS 2, were purified, antibodies raised, and then used in immunofluorescence studies on bovine nasal cartilage (BNC). Punctate localisation was seen with the type II antibody. However, pretreatment of sections with hyaluronidase to remove the proteoglycan resulted in diffuse staining over all the section with this antibody. Antibodies to 1 alpha 2 alpha 3 alpha, C-PS 1, and C-PS 2 collagens gave no staining on untreated BNC sections, but after treatment with hyaluronidase all 3 antibodies showed as a diffuse 'halo' round each chondrocyte lacuna. Anti-type I, anti-type III, and anti-type IV collagen antibodies did not stain untreated or enzyme treated BNC. Type V collagen antibodies gave a bright ring in the pericellular region of the lacunae of hyaluronidase-treated BNC. This was unexpected, as we could not detect type V collagen biochemically in the same cartilage. Anti-fibronectin antibodies stained areas distant from the chondrocytes, these areas being distinct from those stained by 1 alpha 2 alpha 3 alpha and C-PS antibodies, suggesting that fibronectin is not associated with these collagens in BNC. These results suggest that different collagen types may have different locations within the cartilage matrix, that proteoglycans may inhibit antibody association with collagen, and that fibronectin is normally not associated with all types of collagen.

Animals↗
PubMed1983

1 Alpha 2 alpha 3 alpha collagen is arthritogenic.

Native 1 alpha 2 alpha 3 alpha collagen (500 micrograms per rat) was both immunogenic and arthritogenic in Alderley Park rats (46% developed arthritis) but only immunogenic in Sprague-Dawley rats. Conversely, native type II collagen (500 micrograms per rat) was immunogenic and arthritogenic in both strains (64% arthritic in Alderley Park strain, 57% arthritic in Sprague-Dawley strain). The inflammatory polyarthritis induced by 1 alpha 2 alpha 3 alpha collagen was similar to that produced by native type II collagen in clinical appearance, time of onset, and histology. Antibodies raised to native bovine type II collagen cross-reacted with native 1 alpha 2 alpha 3 alpha collagen and vice versa. Thus the minor collagen component of cartilage, the 1 alpha 2 alpha 3 alpha collagen, as well as the major collagen component, type II collagen, are immunogenic and arthritogenic in the rat, with strain differences.

Animals↗
PubMed1982

Isolation and native characterization of cysteine-rich collagens from bovine placental tissues and uterus and their relationship to types IV and V collagens.

A simplified procedure for the fractionation and purification of different collagen types from various tissues is described which is particularly efficient in separating type-V from type-IV collagen, and high-mol.-wt. (HMW) aggregates from 7 S collagen. Uterus and maternal villi contain 2 forms of type-V collagen - [alpha 1(V)]2 alpha 2(V) and [alpha 1(V) alpha 2(V) alpha 3(V) - which have been separated on DEAE-cellulose. Uterus however appears to be the richest source of both HMW aggregates and the [alpha 1(V) alpha 2(V) alpha 3(V)] collagen, and a probable relationship between these collagens is discussed.

Amino Acids↗