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Biomedical subjects

J Sela

Publications and source records attributed to J Sela.

123 records · Page 7Linked to original sources
PubMedDate not supplied

Biochemical characterization of matrix vesicles from bone and cartilage.

Extracellular matrix vesicles from bone and epiphyseal cartilage of femur and tibia of rats were isolated by collagenase digestion (crude vesicles) and further purified by sucrose gradient centrifugation. Fractions containing cells and membranes were also isolated from the two tissues. The alkaline and acid phosphatase and ATPase activities, as well as protein content of all fractions including crude and purified matrix vesicles, were assayed. The crude vesicles from both tissues demonstrated a high alkaline phosphatase specific activity (5-20 times higher than in the cell fraction). The total enzyme activities and protein content were significantly higher in all fractions from cartilage than those from bone. A major peak of alkaline phosphatase activity and protein content was obtained following the sucrose gradient centrifugation. The position of this peak was similar for both tissues. The specific activity of alkaline phosphatase of purified matrix vesicles was significantly higher in bone than in cartilage. The phosphatase activities from cartilage and bone showed a similar pH dependence and a similar response to metal ions. Of the metal ions tested (Na+, Mg2+, Zn2+, and Ca2+) only Zn2+ (at 5 mM concentration) inhibited significantly the alkaline phosphatase activity of purified matrix vesicles. The electrophoretic profile of purified matrix vesicles showed eight major protein bands common for both tissues. In addition, cartilage vesicles appeared to possess two peptides not found in bone.

Acid Phosphatase↗
PubMedDate not supplied

Matrix vesicle enzyme activity in endosteal bone following implantation of bonding and non-bonding implant materials.

The effect of bone bonding (KGy-Cera) and non-bone bonding (KGy-213) implant materials on primary mineralization was examined in endosteal bone repair following marrow ablation. Comparisons were made to determine implant effect on concentration and biochemical parameters of matrix vesicles, as contrasted to vesicles in normal bone healing. Matrix vesicle number was determined by high-resolution computerized morphometric analysis, and implant effect on the specific activity of alkaline phosphatase and phospholipase A2 was measured. Bone responses differed according to the composition of the implant material. The bone bonding implant in this study stimulated matrix vesicle formation, alkaline phosphatase specific activity, and, to a lesser extent, phospholipase A2 activity. The effect of the non-bonding implant on healing bone was of suppression of enzyme specific activities and reduced matrix vesicle production. The results indicate that the bone bonding implant material (KGy-Cera) promotes the initiation of primary mineralization, whereas failure of the KGy-213 to bond may be related to toxic materials that leach from the implant and inhibit the normal sequence of events in the mineralization cascade. The results also demonstrate that the implant materials alter the healing process distal to the injury site. Changes observed in the contralateral control limb mimic the changes observed in the injured limb, but at lower magnitude.

Adhesiveness↗
PubMedDate not supplied

Chronic tympanomastoiditis with formation of calculi.

Numerous calculi of varying sizes and shapes were discovered in the mastoid, antrum, and attic during mastoid surgery for persistent chronic suppurative inflammation of the middle ear cleft with retroauricular and external meatal fistulas in an 8-year-old boy. Light microscopic and scanning electron microscopic examinations and x-ray microanalysis revealed the calculi to consist of masses of crystals containing calcium-oxalate and calcium- and magnesium-phosphate. No signs of tuberculosis were found. Since the patient had multiple dysplasias, including ipsilateral macrotia, in addition to chronic otitis media and mastoiditis, it is suggested that the formation of the calculi may have been due to congenital predisposition.

Calcinosis↗
PubMedDate not supplied

Dentinoenamel junction area of a resorbing permanent incisor studied by means of scanning electron microscopy.

The surfaces of enamel and dentin that had become separated from each other presumably in the region of the dentinoenamel junction were examined. The enamel surface at the junction was scalloped; the scallops were made of enamel rods. The dentinal surface showed a mirror image picture, tubular in nature. Both surfaces were granulated, which may indicate that apatite crystals from the two tissues intermingle there.

Child↗
PubMedDate not supplied

Adaptation of Class II Vitremer restorations with and without primer: a morphometric study.

PURPOSE: The aim of this study was to assess the adaptation of Vitremer with and without primer and compare to that of Z100 with Scotchbond Multi-Purpose. METHODS: Fifty-seven Class II cavities were prepared in 32 extracted or exfoliated primary molars. The cavities were randomly assigned to one of three groups and restored as follows: group A, Vitremer with primer (20 preps); group B, Vitremer without primer (19 preps); and group C, Z100 with Scotchbond Multi-Purpose (18 preps). The restored teeth were thermocycled, embedded in acrylic resin, and sectioned. At least three 1-mm thick sections were obtained from each restoration. Adaptation of the materials was assessed by computerized quantitative morphometry using an image analysis system. In addition to the margin, the entire contact length between the tooth and the restorative material was measured. Voids were recorded separately for the base and cavity margins, and the percentage of defected length was calculated. At least three sections of each restoration were assessed. The section with the worst results was selected as the representative of the restoration. RESULTS: Margin defects were present in 14% of all the restorations, equally distributed between the three groups (A, 10%; B, 16%; C, 17%). A significant difference was found between groups B and C when the percentage of defects in the base was assessed. CONCLUSIONS: Vitremer without primer presented considerably fewer voids when compared with Z100/Scotchbond Multi-Purpose. Although no difference in margin defects could be observed between the three groups a better adaptation to the cavity base was seen in the Vitremer restorations without primer. This finding might be of clinical importance and should be tested in other in-vitro and in-vivo studies.

Composite Resins↗