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Biomedical subjects

D Dayan

Publications and source records attributed to D Dayan.

At least 37 records · Page 2Linked to original sources
PubMed1999

Collagen fibres in the wall of odontogenic keratocysts: a study with picrosirius red and polarizing microscopy.

The collagen in the walls of 15 keratocysts was studied histochemically by staining sections with picrosirius red and examining them with polarizing microscopy. This was compared to 15 cases of dentigerous cyst and 15 cases of radicular cyst. Polarization colours of the collagen fibres were recorded according to their width. No differences were found between the polarization colours of thin fibres (<0.8 microm) in all three lesions; the polarization colours of thick fibres (1.6-2.4 microm) in keratocysts were significantly more greenish-yellow when compared with those of dentigerous cysts and radicular cysts. The staining of the collagen fibres in the keratocysts is similar to that reported in odontogenic neoplasms, which suggests that the stroma of keratocysts could be regarded not just as a structural support of the cyst wall, but as playing a part in the neoplastic behaviour of the cyst.

Analysis of Variance↗
PubMed1998

Bursting pressure in anastomotic healing in experimentally induced colitis in rats.

BACKGROUND: Experimental studies on healing of colonic anastomosis have been thoroughly investigated. However, clinical parameters of the healing process of anastomosis in the inflamed colon has not yet been reported. METHODS: In the present study, healing of anastomosis in trinitrobenzene-sulfonic acid-induced colitis in rats was assessed by measuring the bursting pressure and bursting wall tension. RESULTS: On postoperative day 4, bursting pressure and bursting wall tension were significantly lower (P < 0.001) in rats with colitis with or without anastomosis and normal colon with anastomosis, compared with normal colon without anastomosis. On postoperative day 7, bursting pressure and bursting wall tension of normal colon with anastomosis approached that of normal colon without anastomosis. However, bursting pressure and bursting wall tension of rats with colitis with or without anastomosis remained significantly lower (P < 0.001) than the latter. Furthermore, unlike rats without colitis in which perforation occurred mostly at the anastomotic line, the bursting site in colitic rats was predominantly away from the anastomotic line. CONCLUSIONS: These results suggest that in surgery for inflammatory bowel disease, it is the adjoining inflamed bowel wall that is vulnerable to be perforated in response to increasing intraluminal pressure rather than the anastomosis that is braced by the sutures.

Animals↗
PubMed1998

An immunohistochemical study of p53 and PCNA in inflammatory papillary hyperplasia of the palate: a dilemma of interpretation.

OBJECTIVE: Inflammatory papillary hyperplasia of the palate (IPHP) or the granular type of denture stomatitis, is a non-neoplastic lesion characterized histologically by a significant epithelial hyperplasia and inflammatory infiltrate usually caused by trauma and Candida infection. p53 and proliferative cell nuclear antigen (PCNA) are cell-cycle regulators, that when overexpressed, are considered by many investigators as markers of malignant transformation. The objective of this study was to investigate the immunodetection of p53 and PCNA in IPHP, and to correlate these results with the degree of epithelial hyperplasia and inflammatory infiltrate. MATERIALS AND METHODS: In 12 cases diagnosed clinically as IPHP, Candida was cultured from the denture base and the palatal mucosa. Lesions were biopsied and stained with H&E for histomorphometric analysis of the epithelial width and inflammatory infiltrate. PAS and Gram stains were used for screening of Candida. Sections were immunostained with DO-7 for p53 and PC-10 for PCNA. Fifteen palatal biopsies obtained from autopsies of edentulous subjects with normal palatal mucosa served as controls. RESULTS: All cultures of swabs from both the palatal mucosa and denture base were positive for Candida. Candidal hyphae could not be identified in PAS stained sections. Small foci of Gram-positive organisms were found in two cases of IPHP. Epithelial width and inflammation were significantly higher in IPHP than in controls (P < 0.001). A three-fold increase in positively stained cells for p53 and a two-fold increase in positively stained cells for PCNA were seen in IPHP compared with controls (P < 0.001). CONCLUSIONS: Although a significant increase in the immunodetection of p53 and PCNA may indicate a malignant potential, IPHP has never been reported to undergo malignant transformation nor is it associated with cytologic signs of dysplasia. The increase in the epithelial width and inflammation degree is probably associated with the colonization of the denture bases with Candida organisms. The increased detection of p53 and PCNA can be a secondary effect of cytokines originating from both the inflammatory cells and the keratinocytes. Thus, immunodetection of p53 and PCNA by current immunohistochemical methods on archival tissues is neither specific nor sensitive enough to be used as indicators for malignant potential in the absence of cytological dysplastic changes or genetic proof of mutated cell cycle genes.

Aged↗
PubMed1998

Castration prevents calcium channel blocker-induced gingival hyperplasia in beagle dogs.

1. The purpose of this study was to investigate testosterone's role on the calcium channel antagonist oxodipine-inducing gingival hyperplasia in a dog model. 2. Two experiments were conducted using castrated and intact male dogs. Oxodipine was administered orally for 90 days, at a dose of 24 mg/kg/day. In the first experiment, the occurrence of gingival hyperplasia was evaluated. In the second, the gingival index (GI) and gingival hyperplasia index (GHI) were recorded and correlated with serum levels of testosterone. 3. A significant positive correlation between GI, GHI and plasma testosterone was noted. Castrated dogs were injected with testosterone, 4 months after the start of oxodipine treatment, while in the non-castrated dogs, administration of oxodipine was stopped. Castration correlated with lack of GH, while testosterone injection to the same dogs was associated with an increase of GI and GHI. 4. Since it is known that testosterone receptors are present in the gingiva, it is proposed that oxodipine-induced gingival hyperplasia could be mediated by the calcium channel blocker on plasma testosterone levels.

Animals↗
PubMed1997

The source of NMR-detected motional anisotropy of water in blood vessel walls.

2H Double quantum-filtered (DQF) NMR spectroscopy of deuterated water is sensitive to the presence of order in biological systems. This is because the only nuclei that are detected are those with residual quadrupolar interactions due to their anisotropic motion. In the present study, samples of aorta, coronary and carotid arteries, and vena cava were studied in parallel by 2H DQF NMR and by light microscopy. The average quadrupolar splitting, calculated from the NMR data, varies considerably among the different blood vessels, with high reproducibility for each type of vessel. Polarization microscopy examinations using collagen-specific staining with picrosirius red, have shown a variety of color profiles for the different blood vessels. These reflect different physical modes of aggregation (packing and thickness) of collagen fibers. A correlation was found between the NMR parameters and the color profiles of the picrosirius red-stained sections. Treating the blood vessels with 90% formic acid resulted in the elimination of the 2H DQF NMR signal. Histological analysis demonstrated a complete degradation of collagen and muscle, whereas the elastin filaments were preserved. Evidence is given that the 2H DQF NMR signal is dominated by the contribution of water molecules interacting with the collagen fibers.

Animals↗
PubMed1997

Experimental tongue cancer in desalivated rats.

A group of 39 rats underwent excision of the submandibular and sublingual glands and ligation of the parotid ducts through the midventral incision of the neck, while the control group (41 rats) underwent a sham operation. All rats were administered 4NQO in a final concentration of 0.001% in drinking water. At 7, 14, 22 and 28 weeks after administering 4NQO, both groups of rats were killed and their tongues dissected, inspected and then fixed in 10% buffered formalin for histopathological examination. Clinical examination during the first 14 weeks revealed that rats in both groups looked healthy and no differences in body weight were noticed. Afterwards, the average weight gain of the desalivated rats was lower than in the control group (P < 0.01). The number of macroscopic oral lesions increased with time in both groups. However, in the desalivated rats, the first identifiable lesions were seen as early as week 7, whereas in the control group macroscopic lesions were seen only after 22 weeks. Histological examination revealed more affected rats in the desalivated group in the first 14 weeks after administering the carcinogen; lesions showed more severe pathological changes including two cases with evidence of squamous cell carcinoma. The differences between the desalivated groups and control decreased after 22 weeks with almost no differences at the end of the experiment.

4-Nitroquinoline-1-oxide↗
PubMed1996

Histomorphometric evaluation of experimentally induced colitis with trinitrobenzene-sulphonic acid in rats.

Colitis was induced with trinitrobenzene-sulphonic acid (TNB) in rats and a histomorphometric study was performed as a possible scoring system for disease activity. The affected colon was examined 10, 20, 40 and 60 days after TNB administration. Quantitative microscopic analysis was performed on the following histologic parameters: necrosis, mucosal epithelium, muscularis fibres, inflammation, granulation tissue and fibrosis. Clinically, the rats were sick, especially on days 10 and 20 after TNB injection. Concomitantly, a peak necrosis score involving the full thickness of the colonic wall was recorded on day 10. The inflammatory reaction was most intense 20 days after TNB injection. After 60 days, marked epithelial regeneration was seen and most of the inflammatory reaction had subsided. A good correlation was found between clinical features and quantitative histomorphometric characteristics of colitis. The criteria described allow a precise description and quantification of the inflammatory and healing process of TNB-induced colitis in rats.

Acute Disease↗
PubMed1996

The central odontogenic fibroma and the hyperplastic dental follicle: study with Picrosirius red and polarizing microscopy.

The central odontogenic fibroma (COF) is an uncommon odontogenic tumor in which the microscopic appearance is similar to that of the hyperplastic dental follicle (HDF). Distinction between these lesions is based mainly on their clinical and radiologic features. The collagen of 5 cases of COF and 13 cases of HDF was studied histochemically by staining sections with Picrosirius red and examining them by polarizing microscopy. Polarization colors of the collagen fibers of the lesions were recorded according to their width. While no differences were seen between the polarization colors of thin fibers (<0.8 mm) in both lesions, the polarization colors of thick fibers (1.6-2 mm) of COF were significantly more green and greenish-yellow as compared with those of HDF. These findings suggest that the Picrosirius red polarization method can be used as a diagnostic tool to differentiate between COF and HDF..

Azo Compounds↗
PubMed1996

Lectin histochemistry of the submandibular and sublingual salivary glands in rats.

Tissue sections from rat submandibular and sublingual glands were studied with lectin probes to identify terminal sugars of the glycoconjugates in various cell types of the salivary glands. The lectins used in the study were Canavalia ensiformis (Con A), Triticum vulgaris (WGA), Succinyl WGA (S-WGA) Ricinus communis I (RCA-I), Arachis hypogaea (PNA), and Ulex europeaus (UEA-I). The cytoplasm and cell membrane of both the serous and mucous acinar cells present high similarity in the distribution of some sugar residues, but differ considerably in the expression of specific sugars which appear either in the serous or in the mucous cells. The cytoplasm and cell membrane of the serous and mucous acinar cells express Mannose (Man) and Glucose (Glc), but lack Galactose (Gal), and N-acetylgalactosamine (GalNAc). Fucose (Fuc) is present only in the mucous acinar cytoplasm. The moderate to intense binding of WGA to the acinar and ductal cells and the lack of binding of S-WGA, indicate the presence of sialic acid rather than N-acetylglucosamine (GlcNAc). These sialic acid residues are not associated with PNA-binding sugar sequences as pretreatment with neuraminidase is not associated with exposure of additional PNA receptors.

Acetylglucosamine↗
PubMed1995

Intestinal anastomosis healing in rat: collagen concentration and histochemical characterization by Picrosirius red staining and polarizing microscopy.

The study was designed to characterize collagen fibers in the healing intestinal anastomosis of rat by examining collagen concentration and recording the polarization colors of the collagen fibers in Picrosirius red-stained tissue sections. No significant changes in collagen concentration expressed by hydroxyproline content were noted at the anastomotic site at various postoperative time points. In the normal intestine, the predominant polarization colors were in the yellow to yellow-orange range, signifying tightly packed, matured collagen. During the first postoperative week, collagen fibers at the anastomotic region exhibited mainly polarization colors in the green to green-yellow range, implying less packed intermediate collagen fibers. After 2 weeks, collagen fibers at the anastomotic region gradually reacquired their preoperative polarizing texture. These findings strongly suggest that the "quality" rather than the quantity of collagen fibers plays an important role in maintaining the tensile strength of the healing intestinal anastomosis.

Anastomosis, Surgical↗
PubMed1995

In vitro effect of ciprofloxacin on HT-29 human colon carcinoma cell line: assessment of cell proliferation by thymidine uptake and silver nucleolar organizer regions (AgNOR) histomorphometry.

In an in vitro study, the effect of ciprofloxacin was examined on proliferation of HT-29 human colon carcinoma cell line. Cell proliferation was measured by 3H-thymidine uptake and silver nucleolar organizer region (AgNOR) histomorphometry. A significant increase in [3H]thymidine incorporation (p < 0.05) parallel with a significant increase in the mean AgNOR clusters/cells (p < 0.01) was noted after 5 days of cell exposure to ciprofloxacin. It is suggested that the assessment of AgNOR variables is useful in examination of quinolone effect on HT-29 human colon carcinoma cell proliferation.

Carcinoma↗
PubMed1995

Epithelium and connective tissue regeneration during palatal wound healing in desalivated rats--a comparative study.

Reduction of salivary secretion leads to alteration in the physiologic functions of saliva, including the effect on wound healing. The present study evaluates epithelial regeneration as compared with new connective tissue formation during the healing of a palatal wound in a desalivated rat model. Experimental rats underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts. Small or large mucoperiosteal circular wounds, 3 mm or 5 mm in diameter respectively, were produced in the palate. The distance between epithelial margins and the amount of myofibroblasts were determined at 0, 3, 7, 14, 21 and 28 days post-surgery. The distance between epithelial margins of the small wound (3 mm) was similar in experimental and control groups; however, the distance in the large wound (5 mm) was greater (P < 0.001-0.05) in experimental rats. New connective tissue formation, as indicated by the amount of myofibroblasts, was less (P < 0.01-0.05) in desalivated rats with either the small or the large wound between days 3 and 14. The present results indicate that there is a tissue-specific effect of desalivation, and connective tissue is much more sensitive to desalivation than epithelium.

Animals↗
PubMed1995

Referral delay in diagnosis of oro/oropharyngeal cancer in Israel.

The delay, stage at diagnosis and referral pattern of 543 oro/oropharyngeal cancer patients in Israel were investigated. About two-thirds of the malignancies were diagnosed at early stages. In more than two-thirds there was a delay of at least 2 months from the onset of signs and symptoms up to diagnosis, with a non-significant relationship between stage and delay. A significant correlation (P = 0.002) was found between delay and malignancy site. A delay of more than 4 months was observed in 71% of the patients with lip cancer. Cancers of the lip, palate and buccal mucosa were more frequently diagnosed at early stages. A significant correlation (P = 0.001) was found between stage at diagnosis and referral source. Although 86% of the cancers were diagnosed by physicians, nearly half were already at an advanced stage; when the cancers were diagnosed by dentists, 81% of the remainder were at early stages. No significant relationship was found between the referral medical profession and site of diagnosis. No nasopharyngeal, oropharyngeal or laryngeal cancers were diagnosed by dentists.

Adolescent↗
PubMed1995

Ameloblastic fibroma in a young cat.

The results of a histological and histochemical study of an ameloblastic fibroma in the maxilla of a young cat are presented. Staining with Picrosirius red revealed the presence of collagen fibers of abnormal packing in the ectomesenchymal component of the tumor. A discussion relating to the classification of the tumor with reference to those in humans is presented.

Animals↗
PubMed1994

Gingival hyperplasia induced by calcium channel blockers: mode of action.

Gingival hyperplasia is a known side effect in patients treated with diphenylhydantoin, cyclosporin and the calcium channel antagonists. The present study proposes a mechanism by which calcium channel antagonists may induce gingival hyperplasia. The calcium antagonist induces blockage of the aldosterone synthesis in zona glomerulosa of the adrenal cortex since this pathway is calcium-dependent, cyclic nucleotide-independent. This may produce a feedback stimulation of an increase in pituitary secretion of ACTH which affects zona glomerulosa hyperplasia. This hyperplasia is merely related by accumulation of steroid intermediate products (androgens) that are transformed to testosterone because of an increase in 17-alpha-hydroxylase enzyme activity. Elevated levels of testosterone may act on the gingival cells and matrix to produce gingival hyperplasia.

Adrenocorticotropic Hormone↗
PubMed1994

Sucralfate suspension as a treatment of recurrent aphthous stomatitis.

DESIGN: A prospective randomized, double-blind, placebo-controlled, cross-over clinical trial. SETTING: A university hospital. SUBJECTS: Twenty-one patients with symptomatic recurrent aphthous stomatitis (RAS), unresponsive to conventional treatment were enrolled. They were divided into three groups. INTERVENTION: In a cross-over trial, the patients received an oral suspension of sucralfate, an antacid solution or a placebo for 2 years. RESULTS: After 2 years of follow-up, sucralfate was found to be superior to both placebo and antacid (P < 0.001) with regard to duration of pain, reduction of the healing period, response time to first treatment and duration of remission. CONCLUSION: Sucralfate suspension should be added to the armament of treatment modalities of RAS.

Administration, Buccal↗
PubMed1994

Bilateral complex odontoma in a Swiss (CD-1) male mouse.

The present report describes the morphological features of a spontaneous, bilateral, complex odontoma of the incisor teeth in an 87-week-old male Swiss mouse (Crl: CD-1(ICR)BR). This report constitutes the second report of an odontogenic tumour in a Swiss mouse and the first describing a bilateral complex odontoma in this strain of mouse. The report emphasizes the importance of thoroughly examining the oral cavity for dental tumours.

Animals↗