Biomedical subjects

D Dayan

Publications and source records attributed to D Dayan.

At least 55 records · Page 3Linked to original sources

PubMed1994

Polarization microscopy of picrosirius red stained sections: a useful method for qualitative evaluation of intestinal wall collagen.

Collagen pattern in healing anastomosis of intestinal wall was compared with its normal pattern in the submucosal layer. Polarization colours were recorded for thin (0.8 micron or less) and thick (1.6-2.4 micron) collagen fibres. The polarization colours of thick collagen fibres in the anastomotic site were more greenish-yellow and yellow than those in normal intestine which were more yellowish-orange and orange. These findings indicate that the collagen in the anastomotic site 4 days after operation is less packed than the collagen of normal rat intestine. Examination of the polarization colours of Picrosirius red-stained sections is a useful procedure to follow healing of anastomotic sites or diagnosis of collagen pathology in different pathologic conditions in the intestinal wall.

Anastomosis, Surgical↗

PubMed1994

Histochemical study of the blue autofluorescence of collagen in oral irritation fibroma: effects of age of patients and of the duration of lesions.

The intensity of the autofluorescence of collagen was measured in 27 irritation fibromata of the buccal mucosa and 13 of the lip. The intensity of fluorescence correlated positively with the duration of the lesion. The fluorescence intensity also increased with the patients' age. The present observations show that in irritation fibromata of buccal and lip mucosae, the intensity of blue autofluorescence of the collagen increases with duration of the lesions and with the age of patients.

Adolescent↗

PubMed1993

Characteristics of palatal wound healing in desalivated rats.

The healing of excisional wounds in the palate of desalivated rats was evaluated. Experimental rats became desalivated after extirpation of the submandibular and sublingual glands and ligation of the parotid ducts. Small or large circular wounds, 3 or 5 mm in diameter, were produced in the palate. The wound area, area of inflammation, area of connective tissue formation and the number of myofibroblasts were determined at 0, 3, 7, 14, 21 and 28 days after surgery. The area of the small wound (3 mm) was similar in experimental and control groups; however, the area of the large wound (5 mm) was greater in the experimental group (p < 0.05-0.01). The area of inflammation was greater in the experimental group with small or large wounds (p < 0.05-0.01). Connective tissue formation was less (p < 0.01) in desalivated rats with a small wound at day 14 and with a large wound at days 21 and 28. There were fewer myofibroblasts in the large wound of desalivated rats (p < 0.01) than in controls between days 3 and 14. The results indicate that palatal wound healing is delayed in desalivated rats and that larger wounds are more sensitive to desalivation than smaller wounds.

Animals↗

PubMed1993

Lipid pigments.

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Aging↗

PubMed1993

Long-term effect of desalivation on extraction wound healing: a densitometric study in rats.

The study evaluates radiographically the long-term changes that occur during the healing of tooth sockets in a desalivated rat model. Experimental rats underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts. Mandibular left first molars were extracted and the rats killed at 0, 14, 21, 28, 45 and 60 days post-extraction. The mandibles were removed, cleaned of soft tissue, placed on a size 2 dental X-ray film and exposed together with an aluminium stepwedge 0.5-3.0 mm. Socket density was measured using a digital densitometer and related to the equivalent density of aluminium. The density of the image of the apical area of the socket was similar in control and desalivated groups (P > 0.05) throughout the study. However, the density of the image of the crestal area of the socket was lower (P < 0.01-0.001) between days 21 and 60 in desalivated rats. This suggests that desalivation causes a long-term delay in socket healing.

Absorptiometry, Photon↗

PubMed1993

Polarization microscopy of picrosirius red-stained collagen from oxodipine-induced hyperplastic gingiva of beagle dogs.

Using the model of oxodipine-induced gingival hyperplasia in beagle dogs, we investigated the collagen fibres of the hyperplastic gingiva by measuring the polarization colours from Picrosirius-red stained sections. The predominant polarization colours of the thick collagen fibres (1.6-2.4 microns diameter) of male oxodipine-treated dogs were greenish-yellow to yellow, while in controls and in female oxodipine-treated dogs, the same size fibres mostly appeared orange and red. These differences may be indicative of gender variation in the genesis of hyperplastic gingiva in calcium channel blocker treated dogs.

Animals↗

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↗