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At least 685 records · Page 38Linked to original sources
PubMed1990

Detection of human papillomavirus-genomic DNA in oral epithelial dysplasias, oral smokeless tobacco-associated leukoplakias, and epithelial malignancies.

Human papillomavirus (HPV) is an infectious agent that is increasingly associated with mucosal cancers, in particular cancer of the cervix. The present investigation was undertaken in an attempt to determine whether HPV could be easily detected in biopsies of oral tissues, specifically oral squamous cell carcinomas, oral epithelial dysplasias, smokeless tobacco keratoses, verrucous hyperplasia, and verrucous carcinoma. In situ DNA hybridization methods were used to isolate specific HPV genomes. Among 100 instances of benign leukoplakia, only 4% of non-tobacco-related and 10% of smokeless tobacco-related lesions harbored viral sequences. We were able to detect viral sequences in dysplastic lesions 3% of the time. Alternatively, 17% and 20% of the verrucous hyperplasias and verrucous carcinomas were positive for viral nucleic acids. Six percent of the squamous cell carcinomas harbored HPV. On the basis of these findings, it is concluded that HPV of known genotype can be identified in oral premalignant and malignant neoplasms.

Carcinoma in Situ↗
PubMed1992

Diagnostic significance of nuclear DNA content and nuclear area in oral hyperplasia, dysplasia, and carcinoma.

The nuclear DNA content and the nuclear area in hyperplasia, dysplasia, and carcinoma of the oral cavity were quantitatively analyzed by microspectrophotometry. In carcinoma, marked variability of the nuclear DNA content and the nuclear area was found. The mean nuclear DNA content, the variance of the nuclear DNA content, the frequency of cells above tetraploid (4 C), the mean nuclear area, and the variance of nuclear area in hyperplasia and dysplasia were significantly different from these values with carcinoma. In some cases of leukoplakia and verrucous hyperplasia with subsequent malignant formation, the values were beyond the lower limit of carcinoma. The results suggest that the nuclear DNA and the nuclear area are important objective indices for predicting malignant potential of precancerous lesions.

Carcinoma, Squamous Cell↗
PubMed1995

The cancer-promoting effect of N-nitrosonornicotine used in combination with a subcarcinogenic dose of 4-nitroquinoline-N-oxide and 7,12-dimethylbenz (A) anthracene.

PURPOSE: This study was conducted to determine the possible carcinogenic role of N-Nitrosonornicotine (NNN) when combined with subcarcinogenic doses of strong carcinogens dimethylbenz (a) anthracene (DMBA) and 4-nitroquinoline-N-oxide (4NQO) in the hamster cheek pouch. MATERIALS AND METHODS: Eighty-five Syrian golden hamsters were randomly divided into three main groups. Group A contained 35 animals, 20 of which were treated with 0.1% DMBA followed by 4% NNN (A-I), 5 with 0.1% DMBA (A-II), 5 with 4% NNN (A-III), and 5 with mineral oil alone (A-IV). Group B contained 23 animals, 13 of which were treated with 0.5% 4NQO followed by 4% NNN (B-I), 5 with 0.5% 4NQO (B-II), and 5 animals with propyleneglycol alone (B-III). Group C contained 27 animals, 14 of which were treated with 0.1% DMBA followed by 4% NNN and 0.5% 4NQC (C-I), and 13 with 0.1% DMBA followed by 0.5% 4NQO (C-II). All animals were treated three times per week for 16 weeks. A total of 7 animals died during this period. RESULTS: Squamous cell carcinoma (SCCA) developed in eight animals (67%) in the group treated with all three chemicals (C-I), in four animals (33%) treated with DMBA and 4NQO (C-II), in two animals (15%) treated with 4NQO and NNN (B-I), and in two animals (11%) treated with DMBA and NNN (A-I). The difference between the number of animals that developed carcinoma in group C-I and those in groups A-I and B-I was statistically significant (P < .05) and this difference reached a significant value when group C-I and C-II were compared (P < or = .1). There was a direct relationship between the number of tumors produced in animals and the number of different chemicals applied. CONCLUSION: The results of this study indicate that NNN, when combined with subcarcinogenic doses of other strong carcinogens, is a promoter in the development of squamous cell carcinoma and that 4NQO in 0.5% concentration is a stronger carcinogen than 0.1% DMBA.

4-Nitroquinoline-1-oxide↗
PubMed1996

Native cellular fluorescence identifies terminal squamous differentiation of normal oral epithelial cells in culture: a potential chemoprevention biomarker.

Native cellular fluorescence (NCF) is being investigated as an intermediate endpoint biomarker for chemoprevention. Oral epithelial cells were cultured under three conditions to identify a spectral pattern for epithelial differentiation: cells maintained in serum-free keratinocyte growth medium were the least differentiated (KGM cells); cells switched to DMEM/F12 plus 10% FCS were intermediate in differentiation (DMEM/F12/FCS cells); DMEM/F12/FCS cells switched to serum-free DMEM/F12 plus 0.8 M NaCl to induce cornified envelopes were the most differentiated (DMEM/F12/NaCl cells). The differentiation status was characterized using immunohistochemistry and electron microscopy. NCF analysis was able to distinguish terminally differentiated epithelial cells (DMEM/F12/NaCl) from those less differentiated cells (KGM, DMEM/F12/FCS) in several emission (lambda ex 340 nm, lambda em 360-660 nm; lambda ex 365 nm, lambda em 400-700 nm; lambda ex 420 nm, lambda em 440-800 nm) and excitation scans (lambda ex 200-360 nm; lambda em 380 nm, lambda ex 240-430 nm; lambda em 450 nm, lambda ex 250-460 nm, lambda em 480 nm; lambda ex 270-500 nm, lambda em 520 nm). The ability to discriminate terminal differentiation in this in vitro model supports the concept of using NCF as an intermediate biomarker to monitor in vivo mucosal differentiation.

Anticarcinogenic Agents↗
PubMed1991

Electron microscopic changes on the DMBA induced oral precancerous and cancerous lesion in hamster cheek pouch.

Experiments were performed to study the early and late ultrastructural changes during hamster cheek pouch carcinogenesis using a regimen of topical application of 9,10 dimethyl-1-1-2 benzanthracene (DMBA) twice a week in liquid paraffin oil. The DMBA was administered for a period of 2 and 4 1/2 months. Hamsters exposed to DMBA for 2 months developed moderate precancerous changes, whereas the hamsters treated with DMBA for 4 1/2 months developed frank and multiple oral tumors with a cauliflower appearance. The ultrastructural pathological changes seen were considerably increased at 4 1/2 months compared with a 2 month period of DMBA treatment. Untreated and solvent control hamsters cheek pouch treated for 2 and 4 1/2 months with liquid paraffin oil alone did not show any premalignant or malignant changes during this period.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Intra-oral cone radiation therapy for selected carcinomas of the oral cavity.

A study of 101 patients with early carcinomas of the oral cavity, T1 and T2, treated by external cobalt 60 beam and/or intra-oral cone (IOC) radiation therapy between 1964 through 1980 was made. The two year disease-free survival rate, including surgical salvage, was 88% and the local control rate was 85%. The incidence of radiation complications, i.e. soft tissue ulceration and/or osteoradionecrosis, was 14% and varied with various tumor sites and radiation doses delivered. The present review shows that local control and radiation complications are closely related to radiation doses and varies with different tumor sites of the oral cavity. Radiation therapy dosages expressed in terms of TDF values for these lesions are herein recommended. With proper selections of lesions arising from the oral cavity, combined external beam and IOC radiation therapy has been found extremely efficacious in achieving good local tumor control and high survival rates with excellent cosmetic and functional results and minimum radiation sequelae.

Humans↗
PubMed1990

Dose fractionation and regeneration in radiotherapy for cancer of the oral cavity and oropharynx. Part 2. Normal tissue responses: acute and late effects.

The early responses of normal tissues of the oral cavity and oropharynx in 498 patients, and the slowly-developing responses in 268 patients who survived a minimum of 18 months after radiotherapy for squamous cell carcinoma were analyzed. The severity of acute responses correlated with dose intensity. The incidence of severe late responses increased with increase in dose per fraction and was characterized by a low alpha/beta ratio. Severe late responses were significantly associated with severe acute responses independently of dose per fraction and total dose, and were also ameliorated slightly by protraction of treatment time suggesting that some late effects were, at least partly, a consequence of acute injury. Probability of local tumor control correlated with severity of acute response, suggesting that excessive protraction of overall treatment time to minimize acute toxicity may compromise local control of the tumor. There was no demonstrable correlation between the volume of tissue irradiated and the severity of acute or late response.

Carcinoma, Squamous Cell↗
PubMed1994

Influence of plasma GSH level on acute radiation mucositis of the oral cavity.

PURPOSE: To see how pretreatment plasma GSH level influences the severity of acute radiation mucositis of the oral cavity during therapeutic irradiation in patients with oral cancer. METHODS AND MATERIALS: Thirteen patients with squamous cell carcinoma of the oral cavity form the subject material. Radical radiotherapy (60 Gy in 25 fractions over 5 weeks) was given using telecobalt. Pretreatment plasma GSH level was measured by Beutler's method. The normal tissue reaction during radiotherapy was monitored and graded. RESULTS: The GSH levels ranged from 10.6-90.5 microM/L (mean 30.6 microM/L). Those who had higher GSH levels developed less severe mucositis. The mean GSH levels in the groups with different severity of reactions were: Grade 2 (four patients) = 50.7 microM/L; Grade 3 (five patients) = 26.1 microM/L; Grade 4 (two patients) = 20.4 microM/L and Grade 5 (two patients) = 26.1 microM/L; Grade 4 (two patients) = 20.4 microM/L and Grade 5 (two patients) = 13.6 microM/L. CONCLUSION: Plasma GSH estimation has the potential to predict individual sensitivity to acute radiation mucositis and may particularly be useful in hyperfractionated regimes. The study also affirms the radioprotective role of GSH and suggests that this effect is either due to protection against membrane lipid peroxidation (since GSH does not enter the cell freely) or DNA damage (fractionated radiotherapy may permit freer entry of GSH into cell).

Acute Disease↗
PubMed1996

TGF-beta isoforms fail to modulate inositol phosphates and cAMP in normal and tumour-derived human oral keratinocytes.

This study examined inositol phosphate and cAMP regulation by TGF-beta 1, -beta 2 and -beta 3 in normal and tumour-derived human oral keratinocytes. Previous findings indicated that the cell lines expressed TGF-beta cell surface receptors and had a range of response to exogenous TGF-beta 1, -beta 2 and -beta 3 from being refractory to the ligand to marked inhibition. Basal levels of inositol phosphates broadly reflected the differentiation status of the cells as demonstrated by involucrin expression, but did not correlate with responsiveness to TGF-beta 1, as measured previously by thymidine incorporation. Treatment of cells with bradykinin or serum caused up-regulation of inositol phosphate levels; by contrast, TGF-beta 1, -beta 2 and -beta 3 failed to modulate inositol phosphates. In two tumour-derived cell lines, the TGF-beta isoforms had no effect on cAMP levels, despite a significant increase in cAMP using a potent agonist of adenylate cyclase (forskolin). Furthermore, the cAMP analogue, dibutyryl cAMP, failed to mimic the inhibitory or refractory responses of TGF-beta in these cells lines. The results demonstrate that in normal and tumour-derived human oral keratinocytes, TGF-beta signal transduction is not mediated by inositol phosphates or cAMP.

Bradykinin↗