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Biomedical subjects

J Sela

Publications and source records attributed to J Sela.

At least 19 recordsLinked to original sources
PubMed1979

Ultrastructural and biochemical study of extracellular matrix vesicles in normal alveolar bone of rats.

The occurrence of vesicles in the extracellular matrix of alveolar bone of normal young rats was demonstrated by both ultrastructural and enzymatic studies. Transmission electron microscopy revealed abundant vesicles in the matrix. The presence of hydroxyapatite crystals, both within the vesicles and in the matrix, was affiliated with rupture of the vesicular membrane. Calcifying nodules were scarce. High levels of both specific and total activities of alkaline- and pyrophosphatases were found in the fraction of isolated vesicles. This fraction also showed activities of different ATPases and acid phosphatase.

Acid Phosphatase↗
PubMed1979

The relationship between extracellular matrix vesicles and calcospherities in primary mineralization of neoplastic bone tissue. TEM and SEM studies on osteosarcoma.

Primary mineralization in neoplastic tissue was studied in osteosarcoma, correlating observations obtained by SEM to those found with TEM. The process is characterized by extracellular matrix vesicles, distributed in the matrix between the forming neoplastic cells and the calcifying fronts. The occurrence of osmiophilic material and solitary hydroxyapatite crystals within the vesicles is followed by accumulation of apatite crystals, disappearance of the vesicular membrane and formation of calcospherites and calcified fronts. The process described here in neoplastic tissue is essentially similar to primary calcification in normal calcified tissues.

Apatites↗
PubMed1979

Effect of irradiation-timing on the initial socket healing in rats.

The effect of a single dose of 1500 R on early postextraction socket healing was studied in jaws of rats. A severe delay in healing was found in animals irradiated 2 weeks prior to extraction. Retardation of healing to a lesser degree was demonstrated in sockets irradiated immediately after exodontia.

Alveolar Process↗
PubMed1979

Correlative transmission and scanning electron microscopy of the initial mineralization of healing alveolar bone in rats.

Primary mineralization in healing sockets after extraction of molar teeth was studied in rats. The observations obtained by scanning electron microscopy were correlated by transmission electron microscopy. The process is characterized by abundance of extracellular matrix vesicles distributed between the forming cells and the calcifying fronts. The occurrence of osmiophilic material and solitary hydroxyapatitte crystals within the vesicles was followed by accumulation of hydroxyapatite crystals, disappearance of the vesicular membrane and formation of calcospherites that conglomerate into calcified fronts. The process described here in bone healing is essentially similar to primary mineralization in other normal and pathological calcified tissues.

Alveolar Process↗
PubMed1977

Further observations on the relationship between the matrix and the calcifying fronts in osteosarcoma.

Human osteosarcoma biopsies were studied with the SEM using sequential etching with sodium hypochlorite solutions after removal of aluminium or gold coatings. Osteosarcomas differ from normal hard tissues in that the matrix never proceeds to complete mineralization, so that the specimens fragment on hypochlorite treatment. Details of the fibrillar pattern and calcospheritic type of mineralization pattern can be seen in hypochlorite etched, fractured surfaces and mineralizing fronts.

Bone Matrix↗
PubMed1977

Bone remodeling in pathologic conditions. A scanning electron microscopic study.

Bone remodeling in pathologic conditions was studied with the scanning electron microscope (SEM). Benign and malignant ossification were examined in cases of myositis ossificans, ossifying fibroma, osteoid osteoma, and osteosarcoma, Resorption of bone due to invasion by non-ossifying tumors was found in cases of squamous cell carcinoma, adenocarcinoma, ameloblastoma, and multiple myeloma. Bone formation due to excessive production of growth hormone was studied in a case of acromegaly. Resorption of bone due to pathologic processes resembled the pattern found in surfaces which were undergoing resorption by osteoclasts. Lamelar-cortical bone formation in acromegally was similar in nature to normal bone. The deformities were rleated to the excessive continuous osteogenesis that occurs in these instances. Neoplastic ossification was characterized by calcifying globules, the diameters of which ranged from 1 to 3 micron. The surfaces of these globules were constructed of minute calcospherites with diameters ranging from 0.1 to 0.3 micron. It is suggested that the pattern of globular calcification is similar to the type that was found with the SEM in fetal bone and cartilage, during healing of fractured bone, and also with the TEM in normal and pathologic calcification.

Acromegaly↗
PubMed1977

Acinar cell hydropic degeneration induced by intraductal instillation of solutions into the parotid glands of the rats.

Saline or BSA were instilled 2, 5, 8 or 11 times at daily intervals into the parotid glands of rats, via Stensen's duct. Hydropic change of the acinar cells developed after 8 and 11 instillations. Histologically, the lesion was characterized by enlargement of the acinar cells, the cytoplasm of which contained vacuoles displacing the nuclei. In view of the negative results of various histochemical reactions the vacuolization was interpreted as hydropic in nature.

Animals↗
PubMed1977

Cyanide removal of gold from SEM specimens.

The cyanide method is highly recommended for the purposes of the removal of gold coatings from SEM specimens prior to (a) further treatment before further SEM, and (b) staining and mounting for LM.

Animals↗
PubMed1977

Experimental allergic sialoadenitis. X. Chronic destructive parotitis induced in immunized rats by daily intraductal challenges with antigen.

The right parotid duct of rats was instilled five to eight times with bovine serum albumin at daily intervals. Acute parotitis developed in non-sensitized animals, while chronic destructive sialoadenitis ensued in preimmunized rats. The morphological changes were reminiscent of those found in the salivary glands of patients with Sjögren's syndrome.

Acute Disease↗
PubMed1977

The role of bone remodelling in the healing of extraction socket in rats.

Bone remodelling of post-extraction socket was studied in the past by various methods. In the present work, the process was studied with the scanning electron microscope (SEM). The SEM is essential for a three-dimensional description, particularly when hard tissues are involved. Initiation of healing on the first week was characterized by formation of delicate spongy bone. The trabeculae were distributed in a centrifugal pattern around the interradicular bone. Socket healing on the second week consisted of thickened, regularly distributed trabeculae. This was accompanied by resorption and flattening of the peri-socket sharp ridges. The third and fourth weeks were characterized by small bone marrow spaces and a gradual transformation of the trabecular bone to one of cortical-compact nature. The typical characteristics of resorbing, resting and forming surfaces were detected in all phases of socket healing. Two major patterns of ossification could be shown: Firstly, calcification of collagen bundles in osteoblastic lacunae. Concentrations of such lacunae were related to periosteal activity and were also found in areas most probably occupied previously by blood vessels. Another pattern of mineralization was in the form of globular calcospherites and is reminiscent of calcification of ground substance.

Alveolar Process↗
PubMed1976

Experimental allergic sialoadenitis. VIII. Acute parotitis following intraductal instillation of antiserum to salivary antigens in the rat.

Antiserum to ammonium sulphate-soluble proteins of rat saliva was raised in rabbits. The introduction of this antiserum, via the excretory duct, into the parotid gland of rats induced severe acute sialoadentis. It is suggested that the inflammatory response developed as a result of formation of immune complexes, composed of acinar epithelial antigens and the antibodies introduced from without.

Animals↗
PubMed1976

Experimental allergic sialoadenitis. IX. The regional lymph nodes after antigenic challenges of the parotid glands in rats.

The regional lymph nodes of the parotid gland of rats were examined histologically. The nodes were removed from untreated animals or rats given instillations of BSA or saline into the parotid duct. Anti-BSA antibodies were assessed in the saliva and serum. Patterns of reactivity of the lymph nodes did not correlate with the presence or absence of salivary and serum antibodies. The occurrence of antibodies in the saliva appears to reflect the activity of immunocytes residing in the parotid gland. The morphological features of the lymph nodes correspond to the overall immunological experience.

Animals↗
PubMed1976

Tissue antigens in the saliva of rats. Demonstration of salivary gland specific and nonspecific antigens.

Antisera were raised in rabbits against the half-saturated ammonium sulfate soluble fraction of rat saliva. With these antisera, at least four antigens were demonstrated by immunodiffusion in the saliva and in a saline extract of the parotid gland; three of these antigens were also found in a saline extract of the submaxillary gland. Two of the four antigens were salivary gland specific, the other two being shared by the liver,pancreas and testis. The immunofluorescent pattern indicates that these antigens originate from the acinar epithelium of the salivary glands and probably constitute products of secretion and/or cellular turnover.

Animals↗
PubMed1975

Antibodies in the saliva after antigenic challenge of the parotid gland of systemically sensitized rats.

Anti-BSA antibodies were detected in the parotid saliva of untreated rats. In non-sensitized animals, the parotid duct of which was repeatedly instilled with saline or BSA, the antibody titers rose significantly. Introduction of BSA into the parotid gland of sensitized animals was followed by a significant rise in salivary but not in circulating antibodies. The findings demonstrate the relative independence of the local from the systemic immune system.

Animals↗