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Biomedical subjects

D Dayan

Publications and source records attributed to D Dayan.

89 records · Page 5Linked to original sources
PubMed1983

A preliminary study of activation of collagenase in carious human dentine matrix.

Collagenolytic activity in human carious and non-carious dentine matrix was compared. Results confirmed the presence of latent collagenase in demineralized dentine and indicated a slow rate of degradation of collagen substrate. Collagenolytic activity was enhanced with the addition of trypsin-TPCK to the demineralized dentine. More activity was observed in the carious dentine, suggesting the presence of collagenase activators or partial enzymic destruction of the inhibitor in the collagen-collagenase-inhibitor complex. It seems that during dentine development collagenase-inhibitor complex is secreted and bound to collagen-dentine matrix, and the enzyme can be activated during the process of dental caries.

Dental Caries↗
PubMed1983

Oriental hornet venom enhances wound healing and repair in rat skin, possibly through its collagenolytic activity.

Oriental hornet (Vespa orientalis) venom sac extract (VSE) was topically applied to experimental wounds produced on the back skin of rats in order to observe histologically its effect on the healing process. In other studies the collagenolytic effect of VSE was investigated. The results clearly indicated that application of VSE enhanced the process of wound healing. Two weeks after wound induction a thick epidermis and maturation of the dermal connective tissue were seen in the experimental animals, whereas in the controls the dermis was thin and still showed granulation tissue, and the epidermis was thin. Incubation of VSE with purified neutral salt-soluble collagen (NSSC) labeled by reduction with [3H]NaBH4 brought about degradation of the substrate. It is assumed that VSE enhances the process of wound healing in the skin, probably due to its collagenolytic effect.

Administration, Topical↗
PubMed1979

Lipofuscin in human tongue muscle.

In a study of 107 tongue specimens lipofuscin granules were found to be present in the muscle fibers of 93% of the cases. The pigment was not found in young individuals under the age of 18 years. The pigmented granules, which were stored in clusters of different sizes at the nuclear poles, were PAS-positive, stained black or brown with the Masson-Fontana procedure, black with Sudan black, and strong purple-pink with Ziehl-Neelson staining; yellow autofluorescene was emitted in ultraviolet light. The morphology, histochemical reactions and autofluorescence of the pigmented granules were characteristics of the endogenous lipid pigment described as lipofuscin. Statistical analyses indicated a direct correlation between increase in quantity and distribution of the pigment and increase in age (P = 0.001), in both males and females. Accumulation of the pigment in the tongue with aging was found to be similar to that in the myocardium.

Adolescent↗
PubMedDate not supplied

Nodular fasciitis of the oral mucosa: light and electron microscopy study.

Nodular fasciitis of the oral mucosa is a rare lesion. The present article describes an additional case and discusses the difficulties in the histologic diagnosis. The final diagnosis is based on immunohistochemistry and electron microscopic morphology. Nodular fasciitis should be considered in the differential diagnosis of swellings in the oral mucosa.

Adult↗
PubMedDate not supplied

Histochemical characterization of collagen fibers in fibrous overgrowth (irritation fibroma) of the oral mucosa: effect of age and duration of lesion.

In a study of 43 specimens of oral mucosa irritation fibroma, polarization colours of collagen thin (0.8 microm) and thick (1.6-2.4 microm) fibers were recorded in formalin-fixed and paraffin-embedded sections stained with Picrosirius red. Examination of polarization colours of both the 'thin' and 'thick' collagen fibers revealed an increase of yellowish-orange and orange fibers as a function of age in patients over 30 years old (P < 0.05 only in thick fibers). When the polarization colours of thin and thick collagen fibers were recorded as a function of duration of the lesion, there was an increase in the number of yellowish-orange and orange fibers and a decrease in blue-green and green fibers in both thin (P < 0.1) and thick (P < 0.05) populations as the lesion matured. These findings show that increments in both the patient's age and the duration of the lesions increase the amount of collagen fibers which exhibit yellowish-orange and orange polarization colours indicating tighter packing and better alignment of the microfibrils, similar to normal mature collagen. These differences may have an effect on the timing of the surgical excision.

Journal Article↗
PubMedDate not supplied

Immediate loading of single-tooth implants: immediate versus non-immediate implantation. A clinical report.

The hypothesis of the present study was that immediate loading of implant-supported restorations replacing single missing teeth could be a successful procedure. The present study compared the clinical success of immediately loaded single-tooth implants placed in fresh extraction sites to that of immediately loaded single-tooth implants placed in healed sites. From the years 1997 to 1998, 26 patients, ranging in age from 18 to 70 years, presented for the placement of 28 immediately loaded implants intended to support single-tooth ceramometal restorations. Nineteen implants were placed into fresh extraction sites, and 9 implants were placed into healed sites. Temporary prefabricated acrylic resin crowns were prepared and adjusted. At the time of traditional second-stage surgery (3 to 6 months after implantation), the implants were restored with single-tooth ceramometal prostheses. The survival rates were 82.4% and 100% for immediate and non-immediate implants, respectively. Follow-up ranged from 6 to 24 months from the day of implant placement, with a mean of 13 months for the immediate implants and 16.4 months for the non-immediate implants. Radiographic marginal bone loss after 3 to 6 months did not extend beyond the abutment-implant junction. Within the limits of the present investigation, immediate loading of single-tooth implants placed in healed sites is a possible treatment alternative. Immediate loading of single-tooth implants placed in fresh extraction sites carried a risk of failure approximating 20% in this patient population.

Adolescent↗
PubMedDate not supplied

PCNA in palate and tongue mucosal dysplastic lesions induced by topically applied 4NQO in desalivated rat.

OBJECTIVES: Saliva has been suggested to have a protective role against carcinogens in the oral cavity in animals. Water-soluble 4NQO is a suitable carcinogen to use in examining the role of saliva in oral cancer. The purpose of this study was to follow the changes induced by the carcinogen at the molecular level, as well as the effect of lack of saliva on these changes. MATERIALS AND METHODS: Topical application to the palate of a 0.5% 4NQO solution dissolved in glycol was used for 4 months to induce malignant transformation in a desalivated rat model. Histomorphometric analysis of proliferating cell nuclear antigen (PCNA), a cell cycle regulator and a proliferation marker, was performed. RESULTS: Manifestation of PCNA significantly increased as the observed histologic changes progressed from hyperkeratosis, to mild or moderate dysplasia, severe dysplasia and squamous cell carcinoma. Differences in manifestation of PCNA among the diagnostic groups was significant (p< 0.05). In the desalivated group, PCNA expression was significantly higher than in control and normal groups, in both tongue and palate after 2 and 4 months (p< 0.05). CONCLUSIONS: An unknown component of saliva has a temporary anti-carcinogenic protective effect, which can both delay and decrease the level of proliferation induced by the carcinogen 4NQO. The specific salivary component and the mechanism by which this protective effect is rendered are yet to be discovered.

4-Nitroquinoline-1-oxide↗