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Biomedical subjects

D Dayan

Publications and source records attributed to D Dayan.

At least 19 recordsLinked to original sources
PubMed1992

Inhibition of adherence of Candida albicans to acrylic by a chitin derivative.

The purpose of this study was to assess the effect of a chitin derivative (CSE) on the adherence of Candida albicans to acrylic. Fungal adherence to acrylic dentures is considered an essential step in the development of denture stomatitis. Adherence of C. albicans to acrylic pieces (5 x 5mm) was assessed microscopically using a calibrated ocular objective and expressed as number of adherent yeasts/mm2 of acrylic. CSE was prepared from commercial chitin (crab shell) and from chitin isolated from C. albicans blastospores. The effect of both CSE types on the adherence of C. albicans to acrylic was examined in two experimental systems: CSE present during the adherence assay and acrylic pieces pretreated with CSE prior to the assay. Both CSE types exerted a significant inhibitory effect when tested in the two experimental systems. These findings are significant for possible prevention of denture stomatitis.

Acrylic Resins↗
PubMed1992

Possible pitfalls in rat extended dermal toxicity testing: an hepatic-ocular syndrome.

During a sub-chronic dermal toxicity study, hepatic and ocular toxicity were detected unrelated to the compound being tested. The changes in the liver were characterized by hepatic centrilobular degeneration and fibrosis due to chronic passive congestion. Clinical chemistry results confirmed the active hepatic damage and cholestasis. The ocular changes were limited to the retina where diffuse retinal atrophy was seen originating adjacent to the optic nerve and progressing centrifugally. It is suggested that as a consequence of the bandaging technique, a state of passive congestion and cholestasis resulted. The decrease in flow of bile acids to the intestine caused disturbances in vitamin E absorption. The deficiency of the antioxidant vitamin was responsible for the retinal changes seen.

Animals↗
PubMed1992

A desmoplastic granular cell tumour of the oral cavity: report of a case.

A case of granular cell tumour of the buccal mucosa demonstrating marked desmoplasia is presented. The bulk of the tumour is composed of dense collagenous stroma, which surrounds isolated nests of tumour cells. Since the histomorphologic appearance of this variant is different from that usually seen in this lesion, the diagnosis is supported by immunohistochemical demonstration of S-100 and Vimentin in the tumour cells. The authors believe that this case represents the first report of a desmoplastic granular cell tumour of the oral tissues.

Cell Nucleus↗
PubMed1992

Effect of salivary gland hypofunction on the healing of extraction wounds: a histomorphometric study in rats.

The effect of salivary gland hypofunction (SGH) on oral wound healing is not well established. The present study evaluates the healing of extraction wounds in a SGH rat model. Experimental rats underwent removal of the submandibular and sublingual glands and ligation of the parotid ducts. Maxillary left first molars were extracted and healing was determined at 0, 1, 3, 5, 7, 10, 14, and 21 days after extraction. Salivary gland hypofunction caused a significant delay in socket healing. The inflammatory process was more intense and of longer duration. The formation of fibrous connective tissue and bone was relatively slow among the experimental rats. The results suggest that SGH patients undergoing oral surgery may have prolonged wound healing.

Alveolar Process↗
PubMed1992

Healing of experimental wounds in sialadenectomized rat.

The present study evaluates the healing of an experimental standardized full thickness excisional wound in the palate of a sialadenectomized rat model. Experimental rats underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts. A full thickness circular wound, 3 mm in diameter, was produced in the palate. Wound diameter was measured clinically and the area of inflammation and area of new connective tissue formation were determined histologically at 3, 7, 14, 21 and 28 days post-surgery. Wound diameter was similar in both the experimental and the control groups. The area of inflammation, however, was larger (p less than 0.05) in experimental rats at days 3, 7 and 14. New connective tissue formation was less (p less than 0.05) in sialadenectomized rats at days 14 and 21. The present results indicate that palatal wound healing is altered and delayed in sialadenectomized rats.

Animals↗
PubMed1992

Thickening of the adrenal zona glomerulosa in dogs induced by oxodipine, a calcium channel blocker.

Subchronic effects of oxodipine, a calcium channel blocker affecting the adrenal gland of the dog, are described. Thirteen wk of treatment at a high dose (24 mg/kg/day) of oxodipine resulted in drug-induced thickening of the zona glomerulosa and increased stimulation of its secretory activity. It is postulated that subchronic administration of oxodipine at this dosage resulted in a decrease in blood pressure, with uninterrupted stimulation of the adrenal zona glomerulosa to release aldosterone, causing an increase in the width of this portion of the gland involving cellular hyperplasia. Support for this indirect effect is found in the increased presence of renin granules in the juxtaglomerular apparatus.

Adrenal Glands↗
PubMed1991

Lipid pigment (lipofuscin) accumulation in rat tongue muscle with aging.

Lipid pigment (lipofuscin) was examined in perioral and tongue muscles of aging rats. While in perioral striated muscle the pigmented granules could not be found, a considerable accumulation with aging could be noted in the tongue muscle. Unlike the human tongue muscle, in which the pigmented granules were stored in clusters of different sizes at the nuclear poles of the muscle fibers, in rats, they were scattered randomly through the cytoplasm. The results of this study suggest that lipofuscin can be used as a marker for aging of the tongue muscle in the rat.

Aging↗
PubMed1991

Intravascular papillary endothelial hyperplasia of the mandibular mucosa.

Intravascular papillary endothelial hyperplasia (IPEH) usually presents as a cutaneous lesion consisting of a reactive proliferation of endothelial cells that arise in an organizing thrombus. This lesion can easily be mistaken for an angiosarcoma. Oral presentations are rare, and when they do occur the most common site is the lip. A rare case of IPEH affecting the mandibular buccal mucosa is described.

Connective Tissue↗
PubMed1991

Connective tissue nevi collagens. Study with picrosirius red and polarizing microscopy.

Biopsy specimens of five connective tissue nevi were examined under crossed polars after staining with Picrosirius red. One biopsy specimen was from a solitary nevus, another from a Shagreen patch. The other three specimens were of erupted nevi. In all cases, thick (as well as thin) collagen fibers appeared green to yellow. In contrast, thick fibers of normal human dermis appeared orange to red. The findings indicate that the collagen of collagenous connective tissue nevi is less well packed than normal collagen. Examination of the polarization colors of Picrosirius red-stained sections is a useful procedure for diagnosing collagenous connective tissue nevi.

Adult↗
PubMed1991

Spontaneous ameloblastic fibro-odontoma in a female mouse.

A spontaneous ameloblastic fibro-odontoma is described in a 73-wk-old female mouse. The tumor was located in the molar mandibular region. The diagnosis was made on the basis of the histologic presence of odontogenic epithelial tissue embedded in mesodermal tissue resembling dental papilla, and containing in addition dentin and enamel. The positive reaction for keratin and vimentin confirmed the presence of ectodermal and mesodermal elements respectively in the tumor.

Animals↗
PubMed1991

Extraction wound healing in desalivated rats.

Wound licking has been shown to promote extraoral wound healing among animals. Although the oral mucosa is bathed in saliva. Little information about the role of saliva in oral wound healing is found. The present study evaluates the healing of extraction wounds in desalivated rats. Experimental rats underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts. Maxillary left first molars were extracted. Rats were killed at 0, 1, 3, 5, 7, 10, 14, and 21 days after surgery and maxillae were prepared for light microscopy examination. Generally, a delay in socket healing in the desalivated rats was found. No differences were observed in blood clot formation. Replacement of the clot by granulation tissue was relatively slow concomitant with a longer inflammatory process. Bone formation kinetics were slower among the experimental rats.

Animals↗
PubMed1991

Adult and infantile myofibromatosis: a report of three cases affecting the oral cavity.

Myofibromatosis is a rare but well recognized entity which was originally thought to affect only neonates and infants. It is now apparent however that adults may also be affected. Solitary cases affecting the oral cavity appear to be rare and only two cases of solitary lesions in adults appear in the literature. This report documents three solitary cases; two typical lesions in infants and a lesion from the tongue of an adult. The lesions were composed of small polygonal cells and large elongated cells in a scant fibrous stroma. The elongated spindle cells were identified as myofibroblasts by immunocytochemistry and electron microscopy. The lesions showed characteristic features which enabled them to be distinguished from other fibrous lesions and from benign or malignant smooth muscle tumors with which they have frequently been confused.

Actins↗
PubMed1990

Developmental anomaly of permanent teeth related to traumatic injury.

A case is presented where a 4-year-old girl was injured in an automobile accident. The dental injury, intrusive luxation of the maxillary deciduous incisors, seemed unimportant at the time, since the child was in critical condition. The situation was first evaluated 5 years later, when the child was referred for treatment of an apical periodontitis originating from the right central incisor. The present case reflects several important aspects that were overlooked at the time of injury: the potential of intruded luxated deciduous teeth to cause developmental anomalies to the permanent dentition; the necessity of a longer follow-up period to detect such anomalies; and the need to develop effective treatment methods.

Child↗
PubMed1990

Bone formation in peripheral giant cell granuloma.

Mineralized products were analyzed in a series of 62 cases of peripheral giant cell granuloma of the gingiva or alveolar ridge of man. Histologic sections were examined by routine light microscopy and under polarized light to assess the extent and composition of mineralized tissues in these lesions. In 35% of the cases, mineralized tissue was identified in the form of woven and/or lamellar bone and dystrophic calcification. The most common type was the woven bone which appeared alone or in combination with lamellar bone in 82% of the lesions containing mineralized material. Unlike peripheral ossifying fibroma, no cementum-like material was identified in peripheral giant cell granuloma.

Adolescent↗
PubMed1989

Are the polarization colors of picrosirius red-stained collagen determined only by the diameter of the fibers?

Polarization colors of various purified collagens were studied in fibers of similar thickness. Three different soluble collagens of type I, insoluble collagen type I, lathyritic collagen type I, two p-N-collagens type I, pepsin extract collagen type II, two soluble collagens type III, p-N-collagen type III, and soluble collagen type V were submitted to a routine histopathologic procedure of fixation, preparation of 5-microns-thick sections, staining with Picrosirius red and examination under crossed polars. Polarization colors were determined for thin fibers (0.8 micron or less) an thick fibers, (1.6-2.4 microns). Most thin fibers of collagens and p-N-collagens showed green to yellowish-green polarization colors with no marked differences between the various samples. Thick fibers of all p-N-collagens, lathyritic and normal 0.15 M NaCl-soluble collagens showed green to greenish-yellow polarization colors, while in all other collagens, polarization colors of longer wavelengths (from yellowish-orange to red) were observed. These data suggested that fiber thickness was not the only factor involved in determining the polarization colors of Picrosirius red-stained collagens. Tightly packed and presumably, better aligned collagen molecules showed polarization colors of longer wavelengths. Thus, packing of collagen molecules and not only fiber thickness plays a role in the pattern of polarization colors of Picrosirius red-stained collagens.

Animals↗
PubMed1989

Touton-like giant cells in periapical granulomas.

Two types of multinucleated giant cells were observed in periapical granulomas--the foreign body type and the Touton type. In the Touton type, the nuclei were near the center of the cell, surrounded by foamy cytoplasm. Both types of giant cells reacted positively to lysozyme, alpha 1-antitrypsin and alpha 1-antichymotrypsin, indicating their histiocytic origin.

Giant Cells↗
PubMed1989

Myofibroblasts in peripheral giant cell granuloma. Light and electron microscopic study.

Myofibroblasts are found in various pathologic conditions including lesions containing giant cells, such as central giant cell granuloma and the giant cell tumor of tendon sheath (nodular tendosynovitis). In the present study, myofibroblasts were found in peripheral giant cell granuloma (PGCG) using the TP-Levanol fast cyanine 5RN histochemical procedure and electron microscopy. A number of myofibroblasts displayed intracellular collagen fibrils. The presence of myofibroblasts supports the reactive nature of PGCG.

Fibroblasts↗