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Biomedical subjects

S Gay

Publications and source records attributed to S Gay.

At least 235 records · Page 13Linked to original sources
PubMed1987

Developmental appearance of Gla proteins (osteocalcin) and alkaline phosphatase in tooth germs and bones of the rat.

The tissue distribution and developmental appearance of alkaline phosphatase and Gla proteins, relative to mineralization were examined. Undecalcified sections of tooth germs, calvaria and alveolar bone of the rat were immunostained for Gla proteins, (indirect immunofluorescence and avidin-biotin-peroxidase-complex) and then stained for alkaline phosphatase activity. In the growth regions of tooth germs, Gla protein was observed in young odontoblasts and in early predentin, at a stage prior to formation of the first mineralized dentin. Similar results were obtained for bone: young osteoblasts as well as osteoid were immunopositive for Gla protein prior to formation of the first mineralized bone. Histochemical staining revealed that differentiating odontoblasts and osteoblasts exhibited alkaline phosphatase activity at stages prior to appearance of Gla proteins and that cells adjacent to odontoblasts and osteoblasts (not directly involved in the formation of predentin/dentin and osteoid/bone) stained for alkaline phosphatase, but not for Gla proteins. We conclude, that in these bone- and dentin-forming cells, alkaline phosphatase activity is expressed before the appearance of Gla proteins, but that both appear before the onset of mineralization. We also conclude that Gla protein is a more specific marker for bone and dentin formation than histochemical alkaline phosphatase activity, since only the cells directly involved in these processes were immunostained for Gla protein.

Alkaline Phosphatase↗
PubMed1986

LDA-1 monoclonal antibody. An excellent reagent for immunofluorescence mapping studies in patients with epidermolysis bullosa.

To determine the diagnostic usefulness of a monoclonal antibody to the LDA-1 antigen, a newly defined noncollagenous component of the lamina densa of human basement membrane, we examined skin specimens from 20 patients with epidermolysis bullosa (simplex type, eight patients; junctional type, four patients; dystrophic type, eight patients) by the indirect immunofluorescence technique. We compared this antibody to polyclonal antibodies with three other antigens routinely examined in diagnostic immunofluorescence mapping studies. The antigen defined by the LDA-1 monoclonal antibody was expressed normally in all specimens examined, regardless of the type of epidermolysis bullosa present. Furthermore, no disparity was noted between the LDA-1 monoclonal antibody and a polyclonal antibody to type IV collagen in the microscopic localization of binding within induced skin blisters. These findings suggest that the LDA-1 monoclonal antibody is an excellent immunoreagent for diagnostic immunofluorescence mapping studies.

Antibodies, Monoclonal↗
PubMed1986

The extracellular matrix in "sclerosing" follicular center cell lymphomas: an immunohistochemical and ultrastructural study.

"Sclerosis" is frequently seen in follicular center cell (FCC) lymphomas. The mechanism of its deposition, as well as its composition and significance, are unknown. Several clinical studies have suggested that the course of these lymphomas is more indolent than that of lymphomas of the same histologic type without sclerosis. Nine immunologically characterized cleaved FCC lymphomas with sclerosis and 14 reactive lymph nodes with follicular hyperplasia were investigated by special staining methods, electron microscopy, and immunohistochemical studies with antibodies to types I, III, IV, and V collagen, laminin, and fibronectin. The sclerotic tissue in FCC lymphomas stained uniformly with periodic acid-Schiff (PAS) and Masson's stain, with the patterns ranging from delicate filamentous strands to dense doubly refractile bands. Ultrastructurally, the bands of connective tissue were continuous with the adventitia of vessels and composed of varying amounts of banded collagen (types I and III) admixed with filamentous and flocculent material. In all cases the neoplastic lymphocytes were separated from the extra-cellular matrix by fibroblasts and myofibroblasts with long cell processes. Immunohistochemical studies demonstrated intense staining of sclerotic bands with antibodies to fibronectin and type I collagen and, usually, weaker marking with antibodies to types III and V collagen. No significant staining of sclerotic bands was found with antibodies to type IV collagen or with laminin. Weak pericellular staining for type V collagen was present in eight of nine lymphomas and half of the control lymph nodes. These studies suggest that the increased amounts of extracellular matrix in cleaved FCC lymphomas are produced primarily by fibroblasts and myofibroblasts and represent predominantly fibronectin and types I, III, and V collagen. The composition of the sclerotic areas of FCC lymphomas is similar immunohistochemically to that of the capsule and trabeculae of reactive lymph nodes, which are also intimately associated with fibroblasts and myofibroblasts.

Extracellular Matrix↗
PubMed1986

The extracellular matrix is an integrated unit: ultrastructural localization of collagen types I, III, IV, V, VI, fibronectin, and laminin in human term placenta.

The human term placenta is used extensively as a source of extracellular matrix components. To elucidate the tissue distribution and interrelationships of seven of these components, monospecific antibodies directed against collagen types I, III, IV, V, VI, fibronectin, and laminin were reacted with human term placenta and studied by light and electron immunohistochemistry. Type I collagen was the basic structural unit of human term placenta, present as 30-35 nm, cross-banded fibers, often in the form of large fiber bundles. Type III collagen was present as thin 10-15 nm, beaded fibers often forming a meshwork which encased type I collagen fibers. Types V and VI collagen were present as 6-10 nm filaments, often closely associated with types I and III collagen. Type VI collagen also coated collagen fibers of all diameters, enhancing their periodicity, providing a staining pattern often similar to that observed with anti-fibronectin antibodies. Fibronectin was present in both maternal and fetal plasma and throughout the stroma of the chorionic villus, as both free filaments and coating collagen fibers. Basement membranes contained laminin and type IV collagen, but no fibronectin. In summary, the non-basement membrane proteins studied often codistributed with type I collagen, between and apparently attached to fibers, suggesting that they may act as binding proteins, linking type I fibers and bundles, to themselves and to other structures.

Collagen↗
PubMed1986

Localization of type V collagen with monoclonal antibodies in developing dental and peridental tissues of the rat and hamster.

The distribution of collagen type V in developing dental and peridental tissues was investigated with the indirect immunofluorescence technique using unfixed, frozen sections of jaws from 1-2 day old neonatal rats and hamsters. Immunostaining for type V collagens was found both intracellularly and extracellularly in dental tissues of mesenchymal origin. In non-dental tissues, weak immunostaining was observed in the mesenchymally derived stroma surrounding the developing molar tooth germs but was more pronounced in larger cells, probably young osteoblasts in close vicinity to alveolar bone, and in some cells within developing salivary glands. Decalcification revealed a strong immunostaining in the extracellular bone matrices. In the dental tissues, the mesenchymally derived cells of the papilla exhibited an intracellular staining for type V collagen. In odontoblasts, increased immunostaining over that of other pulpal cells was observed just prior to or coinciding with the onset of predentin secretion and reactivity remained high in fully differentiated odontoblasts. A weak staining was observed in predentin but only after the onset of mineralization. As was the case for bone, after demineralization the dentin matrix stained intensely for type V collagen. The results demonstrate that type V collagen is actively synthesized by mesenchymal cells of developing hard tissues and that this type of collagen is an intrinsic component of hard connective tissue matrices. The data suggest that in developing tooth germs type V collagen is not involved in the differentiation process of either odontoblasts or ameloblasts.

Animals↗
PubMed1986

LDA-1: a ubiquitous noncollagenous lamina densa component of basement membrane detected by monoclonal antibody technique.

Using monoclonal antibody technology, a new basement membrane antigen, designated as LDA-1, has been identified. This antigen is expressed in all human tissues thus far examined; within skin it is detectable not only within the dermal-epidermal junction but also within dermal vascular and appendageal basement membranes. In addition to human skin, LDA-1 is also detectable within rabbit but not monkey, rat, mouse, guinea pig, or cow skin. This antigen has been ultrastructurally localized to the lamina densa and to a much lesser extent, the adjacent sublamina densa region. ELISA (enzyme-linked immunosorbent assay) revealed no cross-reactivity between LDA-1 and type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan. In vitro enzymatic studies suggest that LDA-1 is noncollagenous in nature.

Animals↗
PubMed1985

Dystrophic epidermolysis bullosa. A new variant characterized by progressive symmetrical centripetal involvement with scarring.

A patient is reported with a form of epidermolysis bullosa, hitherto undescribed to the best of our knowledge, characterized by the slow centripetal progression of symmetrical blister formation, milia, scarring, atrophy, and nail dystrophy. Electron microscopy, immunofluorescence mapping, and KF-1 monoclonal antibody studies confirm this disease to be a form of dystrophic epidermolysis bullosa, probably of autosomal recessive transmission despite the absence of acral deformities, contractures, mucosal involvement, and growth retardation.

Antibodies, Monoclonal↗
PubMed1985

Etiopathogenesis of the rheumatoid arthritis-like disease in MRL/l mice. I. The histomorphologic basis of joint destruction.

MRL/l mice spontaneously develop a hindlimb arthropathy, as well as a number of immunologic abnormalities, including circulating rheumatoid factors. Although previous studies have suggested that this arthropathy is primarily an inflammatory process, we performed a comprehensive histomorphologic study which indicated that inflammation is a late manifestation of MRL/l arthritis. The pathologic changes that occur in the joints of these mice can be divided into 3 stages. The first stage develops between the ages of 7 and 13 weeks and consists of synovial cell proliferation in the joint recesses. The second stage is characterized by continued proliferation of synovial cells which take on an appearance similar to that of transformed mesenchymal cells. The earliest destructive changes occur in the second stage and include marginal erosions, followed soon after by progressive destruction of articular and meniscal cartilage. The final stage is characterized by a diminution of synovial cel proliferation, extensive cartilage destruction, formation of scar tissue and fibrocartilage, and a very moderate infiltration of the synovial stroma by mononuclear and polymorphonuclear inflammatory cells. Throughout the disease progression there is a striking dissociation between inflammatory cell infiltration or exudation and tissue destruction. The histomorphologic similarities between human rheumatoid synovitis and the arthritis of MRL/l mice, as well as the presence of rheumatoid factors, make this mouse strain an excellent model for studying human rheumatoid arthritis.

Animals↗
PubMed1985

Immunolocalization of gamma-carboxyglutamic acid containing proteins in developing rat bones.

The localization of a gamma-carboxyglutamic acid (Gla)-containing protein, BGP (also called osteocalcin) was examined in developing calvaria, alveolar bones and long bones of newborn rats by immunostaining with the peroxidase-antiperoxidase method. In undemineralized tissues osteoblasts of intramembranous bones stained positive; osteoid was negative, whereas young mineralized bone stained weakly. After a mild demineralization all bones stained positive; no staining was found in cartilage, muscles or soft connective tissues. In addition to the osteoblasts, osteocytes were also immunoreactive. Osteoclasts, identified by a subsequent staining for acid phosphatase activity, demonstrated no immunostaining for BGP. These data support the hypothesis that BGP is synthesized by osteoblasts and osteocytes and is subsequently deposited in the mineralizing bone.

1-Carboxyglutamic Acid↗
PubMed1985

Immunolocalization of gamma-carboxyglutamic acid-containing proteins in developing molar tooth germs of the rat.

The localization of dentin gamma-carboxyglutamic acid containing proteins (DGP's) was examined in rat molar tooth germs at various stages of development by immunostaining with the peroxidase-antiperoxidase method. Odontoblasts and their processes stained positive, whereas all other cells were negative. No staining was found in predentin. Dentin stained only after a mild demineralization. The results support the concept that DGP's are deposited by odontoblasts directly into the mineralizing dentin.

1-Carboxyglutamic Acid↗
PubMed1985

Interaction of DNA with connective tissue matrix proteins reveals preferential binding to type V collagen.

The interaction of DNA with type I to VI collagens and laminin was studied in vitro in systems in which the connective tissue components were immobilized, as well as when in solution. In studies on immobilized components, significant binding of DNA was observed only for type V collagen, and the binding of radiolabeled DNA to this component could be effectively inhibited in a concentration-dependent manner by the addition of unlabeled DNA. Similar results were observed in solution assays in which it was observed that DNA binding to type V collagen was dependent on the native triple-helical conformation of the collagen. The preferential binding of DNA to native type V collagen may be due to the relative basicity of type V collagen chains, as well as the unique spatial arrangement of amino acid side chains in the native molecules. The data are of potential clinical relevance in that binding of DNA to type V collagen may represent at least one component of the mechanism whereby DNA and its immune complexes are deposited in connective tissues in certain pathologic conditions.

Animals↗
PubMed1985

Healing of surgically created defects in the equine superficial digital flexor tendon: collagen-type transformation and tissue morphologic reorganization.

Full-thickness defects were surgically created in the superficial digital flexor tendons of the front limbs of 20 horses. Tissues formed within the defect were evaluated histologically, and the collagen composition of the tissue was determined by immunofluorescence. Transformation occurred from loose fibrillar areas of types I and III collagen and pericellular types IV and V collagen to dense bundles of type I collagen fibers. Loose fibrillar areas of types I and III collagen were present after 24 weeks. Histologically, in horses killed after 2 weeks, the tissue within the defect was a randomly oriented mass of fibrovascular tissue. In horses killed after 24 weeks the tissue within the defect resembled normal tendon tissue.

Animals↗
PubMed1985

Healing of surgically created defects in the equine superficial digital flexor tendon: effects of pulsing electromagnetic field therapy on collagen-type transformation and tissue morphologic reorganization.

The effect of pulsing electromagnetic field (PEMF) therapy on the healing of surgically created defects in equine superficial digital flexor tendons was evaluated. Defects were created in both front superficial digital flexor tendons of 20 horses. The defect in 1 limb was exposed to a PEMF for 2 hours daily. The other limb served as a control. Histologic and immunofluorescent evaluations were done in horse killed at postsurgical weeks 2, 4, 8, 12, and 24. Therapy with the PEMF significantly (P less than 0.05) delayed the maturation of the tissue formed within the defect at postsurgical weeks 8 and 12, as determined by histologic examination. The collagen-type transformation was also delayed by the PEMF therapy, but to a degree that was not significant.

Animals↗
PubMed1984

Morphological studies of the epiphyseal growth zone in the brachymorphic (bm/bm) mouse.

Light microscopy, including immunohistochemical techniques, and electron microscopy were performed on epiphyseal growth cartilage from brachymorphic (bm/bm) mice and age-matched phenotypically normal siblings aged 5, 16 and 25 days. In the bm/bm mice light microscopy showed a disturbed columnar arrangement and numerous chondrocytes with pronounced regressive changes. The normal development of proliferative cells into hypertrophic cells was halted and thus only a rather small and ill-defined hypertrophic zone was seen. The calcifying zone was irregular and the normal lacunae were replaced by a densely staining matrix. Using immunofluorescence techniques, the presence of considerable amounts of both type II and type V collagen was demonstrated in the bm/bm mice, while the cartilage from controls contained only type II. Ultrastructurally the lacunar matrix contained bundles of fine fibrils without the typical collagen periodicity which might indicate synthesis of a defective procollagen. Our observations together with the previously demonstrated deficiency of 3'-phosphoadenosine 5'-phosphosulphate, illustrate the complexity of the growth cartilage disturbance in the bm/bm mouse. Most of our findings are at variance with those described in the literature and possible pathogenetic mechanisms for the observed alterations in the growth cartilage are discussed.

Animals↗