Poor Dental Health as a Risk Factor for Alveolar Ridge Malignancies

OBJECTIVE

To determine the association between poor dental health and risk of oral cavity squamous cell cancer (OCSCC) at individual tumor subsites.

STUDY DESIGN

Case-control and cross-sectional METHODS: A case-control study was performed using a population-based cohort in North Carolina (Carolina Head and Neck Cancer Epidemiology Study [CHANCE]). A secondary cross-sectional analysis was performed with an institutional cohort (WashU/Siteman). Cases were adults with primary OCSCC and an identifiable tumor subsite. In the CHANCE cohort, controls were adults without head and neck cancer. In the Washington University/Siteman cohort, patients with tongue cancer served as the comparator group. We used number of missing teeth (categorized 0-6, 7-24, 25-28) as a surrogate for poor dental health, which was self-reported in CHANCE and measured on a pretreatment computed tomography scan in the WashU/Siteman study. Adjusted odds ratios (aORs) for missing teeth were estimated for each tumor subsite using binomial logistic regression models.

RESULTS

Near complete tooth loss (25-28 teeth) was associated with a 3.5-fold increased risk of alveolar ridge malignancy (aOR: 3.51; 95% confidence interval [CI]: 1.14-11.01, P = .03) in the CHANCE study. This association was confirmed in our cross-sectional analysis (WashU/Siteman study) where missing 25-28 teeth was associated with an increased risk of alveolar ridge compared to tongue cancer (aOR: 4.60; 95% CI: 1.97-11.10, P = .001).

CONCLUSIONS

This study suggests an association between poor dental health and risk of alveolar ridge cancer independent of smoking, alcohol use, age, race, and sex. Future prospective and translational studies are needed to confirm this association and elucidate the mechanism of dental disease in alveolar ridge malignancies.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Outcomes of Mesh Cranioplasty in Scalp-Free Tissue Reconstruction: A Systematic Review and Meta-Analysis

OBJECTIVE

To systematically review the literature to determine the prevalence and risk of the free flap and postoperative complications in scalp-free tissue reconstruction with synthetic mesh cranioplasty.

DATA SOURCES

Search strategies created with a medical librarian were implemented using multiple databases in May 2021.

REVIEW METHODS

Two reviewers independently performed the review, data extraction, and quality assessment. Cohort studies of patients with scalp-free tissue reconstruction with or without mesh cranioplasty were included. Studies that did not report whether mesh was used or did not separate outcomes by mesh use were excluded. The primary outcomes were free flap failure and postoperative complications. A random-effects model was used for the meta-analysis to estimate prevalence and prevalence ratios (PRs).

RESULTS

A total of 28 studies and 440 cases of scalp-free tissue reconstruction were included. The pooled prevalence of free flap failures and postoperative complications in patients with mesh cranioplasty was estimated at 7% (95% confidence interval [CI], 3%-17%; p = .85, I²  = 0%) and 21% (95% CI, 14%-31%; p = .44, I²  = 0%), respectively. In a subgroup analysis, mesh cranioplasty was not associated with a significantly increased risk of free flap failure or postoperative complications when compared to cases without mesh cranioplasty; pooled PR 1.21 (95% CI, 0.50-2.88; p = .90, I²  = 0%) for free flap failure and PR 1.85 (95% CI, 0.89-3.85; p = .28, I²  = 19) for postoperative complications.

CONCLUSION

Synthetic mesh cranioplasty does not significantly increase the risk of free flap compromise or postoperative complications. A higher prevalence of postoperative recipient site complications was observed in patients with mesh cranioplasty.

The molecular functions of Biodentine and mineral trioxide aggregate in lipopolysaccharide-induced inflamed dental pulp cells

AIM

To explore the proliferation, adhesion and differentiation response and the underlying mechanisms that occur in lipopolysaccharide (LPS)-induced inflamed dental pulp cells (DPCs) in contact with Biodentine and mineral trioxide aggregate (MTA).

METHODOLOGY

The DPCs were isolated from three healthy donors and named DPC-H1 to DPC-H3. The DPCs were pre-cultured with 2 or 5 μg mL^-1 LPS for 24 h to induce inflammation. The expression of inflammation marker miR-146a was detected by q-PCR. The normal and LPS-induced DPCs were further treated with 0.14 mg mL^-1 Biodentine or 0.13 mg mL^-1 MTA for 24 h. MTT assay and adhesion assay were used to analyse the changes of cell phenotypes. DSPP, AKT and ERK expressions were detected by Western blotting. The data were analysed by Mann-Whitney test or two-way anova. Differences were considered statistically significant when P < 0.05.

RESULTS

In LPS-induced DPCs, Biodentine and MTA treatment neither induced nor aggravated LPS-induced inflammation, but their presence did increase the expression of the odontogenic differentiation marker DSPP. Under 2 or 5 μg mL^-1 LPS-induced inflammation, Biodentine and MTA promoted the proliferation of DPC cells, and significantly in DPC-H2 (P < 0.0001 for both reagents). With the treatment of 2 μg mL^-1 LPS, the cell adhesion of DPCs on the fibronectin-coated culture plates was increased significantly by Biodentine (P = 0.0413) and MTA (P < 0.0001). Biodentine and MTA regulated cell adhesion on the fibronectin-coated culture plates (P < 0.0001 for both reagents) and proliferation (P < 0.0001 for both reagents) via the AKT pathway. However, the AKT pathway was not involved in the expression of DSPP induced by Biodentine and MTA.

CONCLUSION

Biodentine and MTA enhanced the proliferation, adhesion and differentiation of LPS-induced DPCs. The proliferation and adhesion process induced by Biodentine and MTA was via the AKT pathway. However, the cellular differentiation process might not use the same pathway, and this needs to be explored in future studies.

Clinical use of the STOP-BANG questionnaire to determine postoperative risk in veterans

OBJECTIVES

To determine whether STOP-BANG (snoring, tiredness, observed apnea, high blood pressure, body mass index, age, neck circumference, gender) scores are associated with immediate postoperative adverse events in veterans undergoing surgery.

METHODS

In this prospective cohort study, veterans presenting to the presurgical clinic at a Veterans Affairs hospital answered the STOP-BANG questionnaire, which was scored as high risk (5-8), intermediate risk (3-4), and low risk (0-2) for obstructive sleep apnea (OSA), during a 6-month study period. Immediate postoperative respiratory and cardiovascular adverse events were recorded.

RESULTS

The patient population included 1,080 veterans. Ninety-five patients (8.8%) experienced adverse events, of which 74 (6.9%) were respiratory and 21 (1.9%) were cardiovascular in nature. Patients with high-risk STOP-BANG scores (5-8) had significantly greater odds of having an adverse event odds ratio (OR) 2.1 (95% confidence interval [CI]: 1.4, 3.3) and hypoxia OR 2.8 (95% CI: 1.7, 4.6) compared to those with low- to intermediate-risk scores (0-4). Among patients with OSA, those with high-risk scores (5-8) had greater odds of an adverse event OR 3.9 (95% CI: 1.1, 13.9) and hypoxia OR 3.7 (95% CI: 1.1, 13.0) compared to those with low- to intermediate-risk scores (0-4). Patients without a history of OSA with high-risk scores (5-8) did not have significantly greater odds of an adverse event OR 1.5 (95% CI: 0.82, 2.6) or a hypoxic event OR 1.7 (95% CI: 0.87, 3.4) compared to those with low- to intermediate-risk scores (0-4).

CONCLUSION

The STOP-BANG questionnaire was useful in the veteran population because high-risk scores were predictive of adverse events, in particular, hypoxia for patients with a previous diagnosis of OSA. In the future, this may direct studies and clinical activities aimed at optimizing safe and effective perioperative practices.

LEVEL OF EVIDENCE

2b Laryngoscope, 129:259-264, 2019.

Oral carcinoma with perineural invasion has higher nerve growth factor expression and worse prognosis

BACKGROUND

This study elucidated the association between histopathological factors and the prognosis of oral carcinoma. As the histopathological factors were determined from the surgical specimen and this can only be used for the choices of postoperative regimens, this study also investigated the linkage between prognostic factors and the expression of key molecules to examine the feasibility of markers as predictors.

METHODS

Clinicopathological factors of 101 oral carcinomas were cross-analyzed with disease-free survival. The expression of nerve growth factor (NGF) and its receptor, tyrosine kinase A receptor, was assayed with immunohistochemistry.

RESULTS

Nodal metastasis was the most crucial clinical predictor for disease-free survival. Perineural invasion (PNI) was an independent histopathological predictor for both nodal metastasis (P = 0.004) and disease-free survival (P = 0.019). Patients with advanced tumor and PNI exhibited the high hazard for tumor progression and poor disease-free survival. NGF immunoreactivity in tumors was correlated with PNI (P = 0.005) and neck lymph node metastasis (P = 0.036).

CONCLUSION

Perineural invasion is the indicator of worst prognosis. As NGF immunoreactivity was found to be associated with PNI and nodal metastasis, the NGF immunoreactivity of oral carcinoma revealed by diagnostic biopsy suggests that alternative therapeutic approaches might be appropriate.

Effects of [123I]ADAM, a serotonin transporter radiopharmaceutical, on pregnant Sprague-Dawley rats

Serotonin transport abnormalities are implicated in neuropsychiatric disorders. [(123)I]ADAM ([(123)I]-2-([2-({dimethylamino}methyl)phenyl]thio)-5-iodophenylamine) is a novel radiotracer that targets serotonin transporters. We assessed the toxicity of [(123)I]ADAM (18.5 MBq) administered in early- and late-phases (8 and 14 day postfertilization, respectively) of pregnancy. The mortality, clinical status, and gross necropsy were measured in pregnant rats, and the fertility index was measured in rat offspring (weight, clinical observations). We found no dosing-related clinical signs. In conclusion, [(123)I]ADAM was not toxic in an animal pregnancy model.

CT analysis demonstrates that cochlear height does not change with age

BACKGROUND AND PURPOSE

CH measurements can often be useful in the diagnosis of inner ear malformations associated with SNHL. Our aim was to establish the relationship between CH and age by using analysis of CT images in patients who underwent coronal CT scans of the temporal bone between 2001 and 2007.

MATERIALS AND METHODS

We measured CH on coronal CT scans of the temporal bone of 422 ears scanned from 2001 to 2007 in 211 patients, 1 month to 23 years of age. Using multivariate linear regression analysis, we determined the relationship of CH to age, sex, and HL type. In addition, 11 patients with multiple scans at different ages were assessed for change in CH with age.

RESULTS

Average CH was 5.3 mm (normal range, 4.4-6.2 mm). Analysis showed no statistically significant change in CH across ages from 1 month to 23 years (95% CI for regression line slope = -0.003, 0.013). Likewise, there were no statistically significant differences in CH for patients with multiple scans at different ages. ICW increased with age as expected with increased cranial size. A small difference in CH between sexes was noted with males having greater CHs than females (P < .01). All patients with hypoplastic cochleas, defined by a CH <2 SDs from the mean (4.48 mm for males and 4.25 mm for females), had HL with a positive predictive value of 86%.

CONCLUSIONS

CH does not change from 1 month of age to adulthood and is slightly greater in males than in females.

Salivary gland anlage tumor in a neonate presenting with respiratory distress: radiographic and pathologic correlation

We present a case of congenital salivary gland anlage tumor (SGAT) of the nasal septum in a 2-week-old infant who had difficulty breathing through her nose since birth. CT and MR imaging demonstrated a circumscribed mass within the nasal cavity that did not communicate with the intracranial compartment. Differential diagnosis and clinical significance of recognizing this rare lesion are reviewed.

The synthesis and characterization of [(124)I]IMPY, a thioflavin-S derivative, in transgenic mouse models of Alzheimer's disease

6-[(124)I]iodo-2-(4'-N,N-dimethylamino)-phenylimidazo[1,2-a]pyridine ([(124)I]IMPY) was synthesized and characterized as a positron-emitting probe to identify Alzheimer's disease in transgenic mouse models. A significant reduction in radioactivity retention in the hippocampus and frontal cortex by co-incubation with nonradioactive IMPY was observed. Highly specific retention of radioactivity in beta-amyloid-rich regions of brain sections was also noted. This study demonstrated that [(124)I]IMPY was a promising probe for the mouse model and may be useful for positron emission tomography to image beta-amyloid plaques in the human brain.

Daily feeding of fresh Neem leaves (Azadirachta indica) for worm control in sheep

This study was Conducted To Evaluate The Anthelmintic Effect Of Neem (azadirachta Indica) On Nematode Parasites Of Sheep. Twelve Santa Ines Cross Bred Sheep From A Government Farm were randomly selected and equally divided into control (n = 6) and treated groups (n =6). Faecal egg counts (FEC) using the modified McMaster technique and the FAMACHA score for assessing clinical anaemia were carried out daily and recorded for 6 weeks. At the end of the study all the animals were slaughtered and the total worm count (TWC) was done. The results of FEC showed that there was no significant difference between the control and treated group (p = 0.081). However, worm burden estimations showed that the number of parasites was significantly higher in the control group compared to the treated group (p < 0.05). This result indicated that feeding Neem had an effect on worm numbers in sheep, but was not reflected in their faecal egg counts. Further work is needed to reconfirm the effect of Neem on helminth infections of sheep.

The organisation of the Department of Veterinary Services in Malaysia

The Department of Veterinary Services (DVS) in Malaysia was established in 1888 as an agency to control exotic and domestic animal diseases. Over the years, the structure and functions of the organisation have evolved to meet the growing demand for veterinary services. The responsibilities of the Veterinary Services are enshrined in the Constitution of Malaysia. The current organisation of the DVS is structured to achieve the following objectives:---to prevent, control and eradicate animal and zoonotic diseases--to facilitate the growth and development of a strong animal industry--to ensure that animal products for human consumption are wholesome, clean, safe and suitable to be consumed--to facilitate the growth and development of the animal feed industry--to ensure the welfare and well-being of all animals. To meet these objectives the DVS has nine different divisions, as follows: Planning and Evaluation, Epidemiology and Veterinary Medicine, Veterinary Public Health, Research and Development, Industry Development, Production and Development of Genetic Resources, Human Resource Development (HRD), Enforcement, and Administration. The development of the animal industry is managed through national development policies, including the Third National Agriculture Policy. The basis for current programmes for disease control and animal industry development is the Eighth Development Plan (2001-2005). Over the period of this Plan, Malaysia will address the need for sanitary and phytosanitary measures by developing specific programmes covering all fields of the animal industry. This is just one way in which Malaysia is meeting the challenges of the increased liberalisation of trade created by the World Trade Organization and the Association of Southeast Asian Nations Free Trade Area. The development of the industry is focused on the major commodities, namely, beef, mutton, poultry meat, eggs, pork and milk. Other commodities receive support if it is considered economically viable. All support services are being strengthened, particularly the HRD division. The organisation and functions of the DVS are constantly being reviewed in accordance with changes in the animal industry and the nature of the services in demand.

Efficacy of Helicobacter pylori eradication on platelet recovery in children with chronic idiopathic thrombocytopenic purpura

AIM

Little is known about the influence of environmental factors on the epidemiology of idiopathic thrombocytopenic purpura (ITP). The role of Helicobacter pylori infection in relation to the development and/or persistence of ITP in infected patients remains controversial. Therapy used for eradicating H. pylori has led to a rise in platelet counts in a significant number of adult patients. but few paediatric studies have been undertaken to evaluate such treatment. The aim of this prospective study was to determine the prevalence of H. pylori and to evaluate whether H. pylori eradication can induce chronic ITP regression in children.

METHODS

To investigate new, noninvasive techniques for diagnosis of H. pylori infection, an enzyme immunoassay for H. pylori antigens in faeces (HpSA) was evaluated. Patient eligibility criteria included isolated thrombocytopenia (< or = 50 x 10(9) L-(-1)) for more than 6 months without any identifiable cause and either normal or increased marrow megakaryocytes. H. pylori status was monitored before eradication and 4, 12, and 24 mo, after the end of treatment using Premier Platinum HpSA.

RESULTS

In this study we evaluated 22 chronic ITP patients, 9 of whom were infected with H. pylori. Using repeated HpSA testing, we demonstrated for eradication of H. pylori after treatment in all infected patients. Five of the nine patients had increased platelet counts that persisted throughout the follow-up period.

CONCLUSION

These results should stimulate additional research into the involvement of H. pylori infection in chronic ITP in childhood. This approach may offer an accepted algorithm at least for some of these patients.

Efficacy of Helicobacter pylori eradication on platelet recovery in children with chronic idiopathic thrombocytopenic purpura

AIM

Little is known about the influence of environmental factors on the epidemiology of idiopathic thrombocytopenic purpura (ITP). The role of Helicobacter pylori infection in relation to the development and/or persistence of ITP in infected patients remains controversial. Therapy used for eradicating H. pylori has led to a rise in platelet counts in a significant number of adult patients. but few paediatric studies have been undertaken to evaluate such treatment. The aim of this prospective study was to determine the prevalence of H. pylori and to evaluate whether H. pylori eradication can induce chronic ITP regression in children.

METHODS

To investigate new, noninvasive techniques for diagnosis of H. pylori infection, an enzyme immunoassay for H. pylori antigens in faeces (HpSA) was evaluated. Patient eligibility criteria included isolated thrombocytopenia (< or = 50 x 10(9) L-(-1)) for more than 6 months without any identifiable cause and either normal or increased marrow megakaryocytes. H. pylori status was monitored before eradication and 4, 12, and 24 mo, after the end of treatment using Premier Platinum HpSA.

RESULTS

In this study we evaluated 22 chronic ITP patients, 9 of whom were infected with H. pylori. Using repeated HpSA testing, we demonstrated for eradication of H. pylori after treatment in all infected patients. Five of the nine patients had increased platelet counts that persisted throughout the follow-up period.

CONCLUSION

These results should stimulate additional research into the involvement of H. pylori infection in chronic ITP in childhood. This approach may offer an accepted algorithm at least for some of these patients.

Splenic abscess caused by group A beta-haemolytic streptococcus

A case of a pyoderma complicated with splenic abscess and bacteraemia caused by group A streptococcus was treated successfully with antibiotics alone for 4 weeks. To our knowledge, this is the first reported case of splenic abscess associated with group A streptococcal bacteraemia. Advances in antibiotic therapy and imaging techniques have improved the management and outcomes of splenic abscesses. Clinicians should be aware of the possibility of splenic abscess after a pyoderma or a sepsis-like episode.

CONCLUSION

Splenic abscesses can be diagnosed by serial ultrasound or CT scan examinations and should be treated with antibiotics for 4-6 weeks.

UDP-glucose dehydrogenase gene of Xanthomonas campestris is required for virulence

Xanthomonas campestris pv. campestris (Xc) is the casual agent of black rot in crucifers. The Xc gene (udgH) coding for UDP-glucose dehydrogenase, an enzyme catalyzing the conversion of UDP-glucose to UDP-glucuronic acid, was previously shown to be required for the biosynthesis of xanthan gum, a substance necessary for the bacterium to cause disease. In this study, the transcription start site of the udgH was determined and the promoter activity monitored by the xylE reporter system indicated that expression of the udgH increases following cell growth and that the udgH gene may possess a second promoter that is responsive to stationary-phase change retaining high levels of expression. Results of Southern hybridization suggest that the udgH gene may be ubiquitous in Xanthomonas, coincident with the notion that members of this genus are capable of xanthan gum biosynthesis. Mutation of the udgH gene in Xc and X. campestris pv. vesicatoria, the casual agent of leaf spot in pepper and tomato, was found to cause a loss of virulence.

Epstein-Barr virus-associated hemophagocytic syndrome masquerading as lymphoma: a case report

Virus-associated hemophagocytic syndrome (VAHS) is a non-neoplastic, generalized histiocytic proliferation with prominent hemophagocytosis associated with a systemic viral infection. Although Epstein-Barr virus (EBV) is one candidate virus for this association, thorough serologic and molecular biologic studies to determine the presence of the viral infection have been lacking in many reports. Whereas elevated liver function tests are common findings in patients with VAHS, exudative ascites and abdominal lymphadenopathy are rare. We describe a case of EBV-AHS masquerading as lymphoma in which treatment with intravenous immunoglobulins was associated with complete clinical remission at 2 years and 6 months after the onset. Regardless of the exact mechanism responsible for ascites formation in VAHS, this case adds support to the possible involvement of EBV in patients with abdominal lymphadenopathy and ascites.

Establishment and characterization of an oral melanoma cell line (ME)

A new cell line, ME, has been established from a melanoma of the palatal mucosa. The cultured monolayer of cells was fusiform and melanin-producing. The cells were highly tumorigenic and metastatic in nude mice. The xenographic tumors resembled the original tumor in morphology, melanin production, and the expression of S-100 and HMB-45 antigens. The metaphase karyotype of ME indicated multiple aberrations of chromosomes 2, 3, 5, 7-11, 13, 19, 21 and X. A homozygous loss of the p16/MTS1 gene during the establishment of ME correlated with karyotypic evidence of chromosome 9 abnormalities. Absence of nm23 protein expression and elevated expression of CD44 protein (indicative of metastatic phenotypes) were demonstrated in primary and xenographic tumors. ME cells could be valuable in developing novel therapeutic strategies for oral melanoma.

A case report of primary hyperparathyroidism with severe bony involvement and nephrolithiasis

INTRODUCTION

Although the majority of patients with primary hyperparathyroidism have a relatively asymptomatic benign disorder, there are patients who have a more aggressive disorder.

CLINICAL PICTURE

We report a case of primary hyperparathyroidism presenting during pregnancy complicated by antepartum haemorrhage and severe prematurity. The diagnosis was made postpartum, when her problems rapidly progressed to result in severe neuromuscular weakness, bilateral pathological hip fractures as well as nephrolithiasis.

TREATMENT

Surgical parathyroidectomy was performed. The underlying lesion was a large solitary parathyroid adenoma with cystic elements.

CONCLUSION

Primary hyperparathyroidism is not an innocuous disease and can result in severe morbidity if left untreated.

Menetrier's disease associated with cytomegalovirus infection in a child

Menetrier's disease is a rare disease with unknown etiology characterized by protein-losing hypertrophic gastropathy and hypoproteinemia. We report on a 4-year-old boy who presented with a 2-week history of vomiting and periorbital edema. Upper gastrointestinal endoscopy revealed prominent gastric rugae, while pathological examination showed hyperplastic mucosa with proliferation, elongation, and basal cystic dilatation of the gastric glands replaced by mucous-secreting epithelium, confirming the diagnosis of Menetrier's disease. Virus isolation from urine revealed cytomegalovirus (CMV); and CMV immunoglobulin G and immunoglobulin M antibodies were detected in the serum. His condition gradually improved under omeprazole, with complete histological recovery after 3 months.

Alstrom syndrome with hepatic dysfunction: report of one case

Alstrom syndrome is a rare autosomal recessive disorder associated with early childhood retinopathy, progressive sensorineural hearing loss, truncal obesity, and acanthosis nigricans. We report a 10-year-old boy with Alstrom syndrome presenting with general malaise and abnormal liver function for 1 year. In addition to the above mentioned features, he also had hyperglycemia and hyperinsulinemia. The mechanism responsible for the persistent elevation of liver enzymes could not be identified. To the best of our knowledge, this is the first-reported case of Alstrom syndrome with hepatic dysfunction in Taiwan.

Overexpression of p53 in squamous cell carcinoma of the tongue in young patients with no known risk factors is not associated with mutations in exons 5-9

BACKGROUND

This study investigated the status of the p53 tumor suppressor gene in patients less than 40 years of age who had squamous cell carcinoma of the tongue develop with no known risk factors.

METHODS

Histologic sections from 21 patients were prepared from formalin-fixed, paraffin-embedded tissue and were processed for standard immunohistochemistry for detection of the p53 protein. In addition, tumors were evaluated by single-strand conformation polymorphism and by DNA sequencing to identify potential mutations in the conserved exons (5-9) of the p53 gene.

RESULTS

Eighty-one percent (17 of 21) of the patients overexpressed p53 by immunohistochemical analysis. However, none of these patients demonstrated mutations in exons 5-9 of the gene.

CONCLUSIONS

These data suggest that the molecular mechanisms by which the young individuals with no risk factors had altered p53 function in oral squamous cell carcinoma may differ from those of the more typical population of individuals who have this malignancy develop.

Overexpression of p53 in squamous cell carcinoma of the tongue in young patients with no known risk factors is not associated with mutations in exons 5-9

BACKGROUND

This study investigated the status of the p53 tumor suppressor gene in patients less than 40 years of age who had squamous cell carcinoma of the tongue develop with no known risk factors.

METHODS

Histologic sections from 21 patients were prepared from formalin-fixed, paraffin-embedded tissue and were processed for standard immunohistochemistry for detection of the p53 protein. In addition, tumors were evaluated by single-strand conformation polymorphism and by DNA sequencing to identify potential mutations in the conserved exons (5-9) of the p53 gene.

RESULTS

Eighty-one percent (17 of 21) of the patients overexpressed p53 by immunohistochemical analysis. However, none of these patients demonstrated mutations in exons 5-9 of the gene.

CONCLUSIONS

These data suggest that the molecular mechanisms by which the young individuals with no risk factors had altered p53 function in oral squamous cell carcinoma may differ from those of the more typical population of individuals who have this malignancy develop.

Establishment and characterization of a cell line (HCDB-1) derived from a hamster buccal pouch carcinoma induced by DMBA and Taiwanese betel quid extract

This study identified that the carcinogenesis of hamster buccal pouch (HBP) induced by 7,12-dimethylbenz[a]anthracene (DMBA) was greatly enhanced (18 folds) by a combination treatment with Taiwanese betel quid (BQ) extract. A new cell line, HCDB-1, has been established from induced carcinomas. The cultured monolayer cells were epithelioid in shape with irregular nuclei. They demonstrated abundant cytokeratin and tonofilaments; however, ultrastructural well-organized desmosomes were lacking. The HCDB-1 cell exhibited population doubling in 19 h and was highly tumorigenic in nude mice. A C-->T transition at codon 141 (Ala to Val) of the p53 gene was detected in this cell. This mutation is equivalent to a specific temperature-sensitive mouse p53Ala135Val mutant that causes transformation by shifting to 37.5 degrees C. HCDB-1 is the first cell line established from the HBP model of oral carcinogenesis induced by DMBA/Taiwanese BQ extract. It might be valuable for exploring the molecular pathogenesis of oral cancer.

P53 expression, p53 and Ha-ras mutation and telomerase activation during nitrosamine-mediated hamster pouch carcinogenesis

Squamous cell carcinomas (SCC) induced in hamster buccal pouch (HBP) by 22 weeks of topical N-methyl-N-benzylnitrosamine (MBN) treatment (twice-weekly, 10 mg MBN/ml propylene glycol) were evaluated for: (i) altered expression of p53 using immunohistochemistry (IHC); (ii) mutations in Ha-ras and p53 using PCR/single strand conformation polymorphism (SSCP); (iii) telomerase activity using the telomerase repeat amplification protocol (TRAP). Precancerous lesions were also evaluated using p53 IHC. Hamsters were killed for lesion analysis at either 3 days (group A, eight hamsters, 89 carcinomas) or 7 weeks (group B, six hamsters, 105 carcinomas) following the final MBN application. Between 3 days and 7 weeks post-treatment the proportion of tumors exhibiting p53 IHC activity (at least 10% of nuclei stained using D07 antibodies for detection of both mutant and wild-type p53) fell from 91 to 50%. However, during this same post-treatment period the frequency of tumors analyzed exhibiting confirmed sequence alterations in the conserved exons (E5-E8) of p53 remained constant (5/15 = 33% in group A versus 14/45 = 31% in group B). Heightened expression of wild-type p53 resulting from DNA damage in the immediate post-treatment period is likely to have contributed to the high proportion of group A tumors exhibiting p53 IHC activity. Nearly 80% of the identified p53 mutations were G-->A and C-->T transitions. The identified p53 point mutations occurred at or near (within three codons) of the corresponding hot-spot codons (175, 245, 248 and 273) of human oral SCC. The proportion of group A and group B tumors analyzed exhibiting Ha-ras mutations was 1/15 (7%) and 7/45 (16%), respectively. Only four of the observed eight Ha-ras mutations occurred in codons known to result in activation of this gene. Telomerase activation was demonstrated in 11 of 13 group A tumors (85%) and in 23 of 24 (96%) group B tumors analyzed. The alterations in p53, Ha-ras and telomerase activity observed in this HBP-MBN model are similar in many respects to those observed in the analogous human lesions of the head and neck. This model may be particularly useful for development of cancer chemoprevention regimens and multimodality cancer therapies.

Alterations of adenomatous polyposis Coli (APC) gene in oral squamous cell carcinoma

The present study assessed the roles of Adenomatous Polyposis Coli (APC) tumor suppressor gene during oral carcinogenesis. Reduction of APC transcript levels and APC loss of heterozygosity (LOH) were found in 39% (7/18) and 29% (10/34) cases of oral squamous cell carcinoma (OSCC), respectively. The apparent APC heterozygosity (27%) in non-cancerous matched oral tissue (NCMOT) adjacent to OSCC at an exon 11 locus was significantly lower than normally found in the Taiwanese population (49%). These findings suggest that the allelic status of APC could indicate a cancer risk. No polymorphism of 11307 allele of APC was identified in NCMOT or OSCC. Our data indicated that alterations of APC are frequent molecular changes of OSCC. Advances in understanding of the APC alterations that accompany OSCC development might provide a means for early diagnosis and possibly new therapeutic strategies.

Alterations of p16/MTS1 gene in oral squamous cell carcinomas from Taiwanese

To determine the alterations of the p16/MTS1 gene in oral squamous cell carcinoma (OSCC), we examined in Taiwanese patients the mutation, deletion and methylation of p16/MTS1 in primary OSCCs associated mostly with betel quid (BQ)/tobacco use. Among 110 tumors undergoing mutational analyses, seven (6%) showed mutations in exon 2 or the intron 1/exon 2 splice site. All but one mutation disrupted the encoded proteins. Base transitions represented the vast majority (6/7) of the mutations identified in BQ/tobacco consuming subjects. It was noted that 15/56 (27%) tumors examined by restriction fragment methylation analysis revealed a significant level of methylation in different loci of exon 1 as compared with the respective non-cancerous tissue. Mutation of p16/MTS1 was exclusively identified in carcinomas of buccal mucosa, whereas methylation of the p16/MTS1 promoter region occurred preferentially in carcinomas of the tongue (54%) rather than at other sites (22%). Homozygous deletion was not found in 56 paired samples examined, nor was hemizygous deletion indicated in 12 informative cases. The results indicated aberrant methylation and mutation as the molecular abnormality of p16/MTS1 in the OSCC from Taiwanese.

Coronavirus-induced membrane fusion requires the cysteine-rich domain in the spike protein

The spike glycoprotein of mouse hepatitis virus strain A59 mediates the early events leading to infection of cells, including fusion of the viral and cellular membranes. The spike is a type I membrane glycoprotein that possesses a conserved transmembrane anchor and an unusual cysteine-rich (cys) domain that bridges the putative junction of the anchor and the cytoplasmic tail. In this study, we examined the role of these carboxyl-terminal domains in spike-mediated membrane fusion. We show that the cytoplasmic tail is not required for fusion but has the capacity to enhance membrane fusion activity. Chimeric spike protein mutants containing substitutions of the entire transmembrane anchor and cys domain with the herpes simplex virus type 1 glycoprotein D (gD-1) anchor demonstrated that fusion activity requires the presence of the A59 membrane-spanning domain and the portion of the cys domain that lies upstream of the cytoplasmic tail. The cys domain is a required element since its deletion from the wild-type spike protein abrogates fusion activity. However, addition of the cys domain to fusion-defective chimeric proteins was unable to restore fusion activity. Thus, the cys domain is necessary but is not sufficient to complement the gD-1 anchor and allow for membrane fusion. Site-specific mutations of conserved cysteine residues in the cys domain markedly reduce membrane fusion, which further supports the conclusion that this region is crucial for spike function. The results indicate that the carboxyl-terminus of the spike transmembrane anchor contains at least two distinct domains, both of which are necessary for full membrane fusion.

Association of aberrant p53 and p21(WAF1) immunoreactivity with the outcome of oral verrucous leukoplakia in Taiwan

The expression of p53 and p21WAF1 in 53 oral verrucous leukoplakias (OVLs), mostly non-dysplastic lesions, was investigated to ascertain the role of such events in malignant conversion. Immunohistochemical analysis revealed aberrant p53 and p21WAF1 immunoreactivity in 51% (27 cases) and 75% (40 cases), respectively. After an average follow-up period of three and a half years, histopathological examination revealed that 22 (42%) cases had developed oral squamous cell carcinoma (OSCC), 14 (26%) cases had undergone recurrence, and 17 (32%) cases were free of disease. The oncogenic potential of this subset of premalignant lesions warrants attention. A significant difference in the frequency of OSCC progression/recurrence was noted in lesions bearing aberrant immunoreactivity of either p53 (93% vs 42%; P=0.00008) or p21WAF1 (80% vs 32%; P=0.002) in comparison with lesions without immunoreactivity. This study suggested that the aberrant immunoreactivity of p53 and p21WAF1 may represent important alterations of OVL and could affect the outcome of this lesion.

Safrole-like DNA adducts in oral tissue from oral cancer patients with a betel quid chewing history

Betel quid (BQ) chewing has been associated with an increased risk of oral squamous cell carcinoma (OSCC) and oral submucous fibrosis (OSF). Piper betel inflorescence, which contains 15 mg/g safrole, is a unique ingredient of BQ in Taiwan. Chewing such prepared BQ may contribute to safrole exposure in human beings (420 microM safrole in saliva). Safrole is a known rodent hepatocarcinogen, yet its carcinogenicity in human beings is largely undetermined. In this study, using a (32)P-post-labeling method, we have found a high frequency of safrole-like DNA adducts in BQ-associated OSCC (77%, 23/30) and non-cancerous matched tissue (NCMT) (97%, 29/30). This was in contrast to the absence (< 1/10(9) nucleotides) of such adducts in all of non-BQ-associated OSCC and their paired NCMT (P < 0.001). Six of seven OSF also exhibited the same safrole-like DNA adduct. The DNA adduct levels in OSF and NCMT were significantly higher than in OSCC (P < 0.05). Using co-chromatography and rechromatography techniques, we further demonstrated that these adducts were identical to synthetic safrole-dGMP adducts as well as DNA adducts from 1'-hydroxysafrole-treated HepG2 cells. These results suggest that safrole forms stable safrole-DNA adducts in human oral tissue following BQ chewing, which may contribute to oral carcinogenesis.

Telomerase activity and in situ telomerase RNA expression in oral carcinogenesis

To investigate the role of telomerase in oral carcinogenesis, we assayed telomerase activity in various oral tissues by a modified telomeric repeat amplification protocol (TRAP) analysis. Also, using digoxigenin-labeled probes, we measured the in situ expression of human telomerase RNA component (hTR) in paired oral squamous cell carcinomas (OSCC) and adjacent non-cancerous matched tissue (NCMT). We detected telomerase activity in three OSCC cell lines, but not in primary oral keratinocytes. In patient samples, most OSCC (36/42, 86%) and oral premalignant lesions (8/12, 67%) possessed telomerase activity. In addition, 6 of 27 (22%) NCMT contained weak telomerase activity. In situ hybridization showed that hTR was expressed in almost all OSCC (23/27, 85%) as well as in the majority of NCMT (20/25, 80%). In most cases, accumulation of hTR was observed both in the nucleus and cytoplasm of epithelial cells. A correlation between hTR expression and more advanced tumor grade was observed. The appearance of telomerase activation and hTR expression during oral carcinogenesis was different. This study indicates that the activation of telomerase is an early and frequent event in OSCC.

Differential response to benzo[A]pyrene in human lung adenocarcinoma cell lines: the absence of aryl hydrocarbon receptor activation

Benzo[a]pyrene (B[a]P) has been shown to produce DNA adducts and to initiate pulmonary carcinogenesis in animals. We observed differential susceptibility to B[a]P in two human lung adenocarcinoma cell lines, A427 and CL3. DNA adducts were induced by B[a]P treatment in CL3 cells, however, A427 cells were much less responsive to B[a]P treatment. Cytochrome P450 1A1 (CYP1A1) is involved in bioactivation of B[a]P in nonhepatic tissues. Cotreatment with alpha-naphthoflavone, a CYP1A1 inhibitor, abolished DNA adduct formation by B[a]P in CL3 cells. Nevertheless, CYP1A1 inducer beta-naphthoflavone, enhanced DNA adduct formation by B[a]P in both A427 and CL3 cells. Both enzyme activity and mRNA levels of CYP1A1 were highly induced by 1 or 10 microM B[a]P treatment for 24 hr in CL3 cells but not in A427 cells. Protein levels of AhR and aryl hydrocarbon receptor nuclear translocator (Arnt) were similar in A427 and CL3 cells before B[a]P treatment. However, B[a]P induced a retarded band with the [32P]-dioxin responsive element in CL3 cells, but not in A427 cells. This study demonstrated that variation in AhR-mediated CYP1A1 induction contributes to differential susceptibility to B[a]P-DNA adduct formation in human lung cells. Since AhR and/or Arnt function is impaired in A427 cells, this cell line offers a model for investigating the repression mechanisms of CYP1A1 induction by B[a]P in lung cells.

Pressure ulcers--randomised controlled trial comparing hydrocolloid and saline gauze dressings

An open comparative randomised study comparing the performance of hydrocolloid dressings (DuoDERM CGF) to saline gauze dressings in the treatment of pressure ulcers was done to evaluate the overall dressing performance, wound healing and cost effectiveness. Thirty-four subjects were enrolled at the University Hospital, Kuala Lumpur over a 643 days period. Inclusion criteria were Stage II or III pressure ulcers, at least 18 years of age and written informed consent. Only one pressure ulcer per subject was enrolled in the study. Patients with infected pressure ulcers, diabetes mellitus, an immuno-compromised status and known sensitivity to the study dressings were excluded. Subjects who met the enrollment criteria were randomised to one of the two dressing regimes. They were expected to participate in the study for a maximum of eight weeks or until the pressure ulcer healed, which ever occurred first. Overall subject age averaged 58 years and the mean duration of pressure ulcer existence was about 1 month. Twenty-one of the thirty-four ulcers enrolled were stage II and thirteen were stage III. The majority of the ulcers (88%) were located in the sacral area and seventeen subjects (50%) were incontinent. In the evaluation of dressing performance in terms of adherence to wound bed, exudate handling ability, overall comfort and pain during dressing removal; all favoured the hydrocolloid dressing by a statistically significant margin (p < 0.001). Subjects assigned the hydrocolloid dressing experienced a mean 34% reduction from their baseline surface area measurement compared to a mean 9% increase by subjects assigned gauze dressings. This was not statistically significant (p = 0.2318). In cost evaluation of the study products, there was no statistical significance in the total cost of wound management per subject. When only labour time and cost was evaluated, there was a statistically significant advantage towards hydrocolloid dressings.

Intestinal lymphangiectasia--a report of three Chinese children in Malaysia

This is a report of 3 Chinese children with intestinal lymphangiectasia in Malaysia. Two children responded to a low fat diet and medium-chain triglyceride supplement. The third child has recurrent chylous ascites. None of the children has recurrent infections despite low CD4+ cells and low levels of IgG and IgA. Intestinal lymphangiectasia is a rare congenital disorder of the mesenteric lymphatic that leads to the obstruction of the lymphatics of the intestine and protein losing enteropathy. Restriction of dietary fat intake will usually result in remission. Recurrent chylous ascites is a problem and management can be difficult.

p53 alterations in betel quid- and tobacco-associated oral squamous cell carcinomas from Taiwan

Alterations of p53 have been explored in Taiwanese oral squamous cell carcinomas (OSCCs) consisting of a betel quid (BQ)/tobacco-related subgroup of 36 subjects and a tobacco-related subgroup of 13 subjects. Mutations in conserved exons were found in 12 tumors. Seven mutations were clustered in a hot-spot region mapped to a region between codons 273-282 in exon 8. The incidence of p53 mutation in BQ/tobacco tumors was 22% (8/36). The frequency of p53 allelic loss (21%, 3/14) in BQ/tobacco tumors approximates to the incidence of mutation. This is the first study demonstrating allelic deletion of p53 in such malignancies. Twenty-four of 43 samples showed positive p53 immunostaining. All tumors harboring mis-sense mutations of p53 in conserved exons exhibited nuclear protein accumulation. The incidence of mutation in conserved exons in BQ/tobacco-associated Asian OSCCs (15%) is significantly different from worldwide OSCCs (46%) related primarily to tobacco consumption (P=0.00001).

Sebaceous carcinoma of buccal mucosa. Report of a case

A case of sebaceous carcinoma arising in the buccal mucosa is described.

Laser diode to single-mode fiber ball lens coupling efficiency: full-wave calculation and measurements

We show that the coupling efficiency from a laser diode (LD) to an optical fiber through a ball lens can be calculated accurately using the exact solution to Maxwell's equations for the scattering of a beam from a dielectric sphere. Our calculated results agree closely with coupling measurements from an asymmetric LD for two different ball lenses.

MTS1 gene mutations in archival oral squamous cell carcinomas

Multiple tumor suppressor gene 1 (MTS1) has been found mutated or deleted in a variety of human cancers. Our purpose was to identify and characterize MTS1 gene mutations in primary oral squamous cell carcinomas (SCCs) in each of the three exons of the MTS1 gene. Seventeen archival samples of oral SCC were evaluated for the presence of MTS1 mutations using single strand conformation polymorphism (SSCP) and DNA sequencing. Three of 17 tumors exhibited MTS1 gene mutations: one tumor exhibited a mutation in exon 2 and two tumors exhibited mutations at the splice site junction of intron 2 and exon 3. Three tumors also exhibited a common base change in the 3' untranslated region of exon 3, which is interpreted as a likely polymorphic variant. An examination of the three tumors exhibiting MTS1 point mutations revealed no unique characteristics relative to p53 immunohistochemical activity, mitotic frequency, or degree of histologic differentiation. This study indicates that MTS1 gene mutations may be involved in at least a minor proportion of oral SCCs.

Blue Pr(3+)-doped ZBLAN fiber upconversion laser

We demonstrate blue laser emission from a direct semiconductor laser-diode-pumped Pr(3+)-doped upconversion fiber laser. This laser produced more than 1 mW of power at a wavelength of 492 nm from pump lasers operating at 830 and 1020 nm.

The effects of continuous versus interrupted noise exposures on distortion product otoacoustic emissions in guinea pigs

Distortion product otoacoustic emissions (DPOAE) were measured serially in guinea pigs before and following 4-h exposures to a half-octave band of noise centered at 6 kHz. Stimulus parameters used to elicit the DPOAE were f2/f1 = 1.26 and L2 = L1-10. The 80 dB SPL exposures resulted in attenuation of emissions, which was maximal at the frequency one-half octave above the exposure when referenced to the f2 stimulus, and which recovered back to baseline after 2 days. The 90 dB SPL exposures resulted in a permanent deficit in emissions elicited by high-frequency stimuli, as measured after 8 days of recovery. A statistically significant difference was also found between animals exposed continuously for 4 h versus animals given two 2-h exposures separated by a 1-h break. Measures of f2-f1 and 3f1-2f2 indicated that they were more sensitive than 2f1-f2 to alterations in cochlear function after noise exposure.

p53 and Ha-ras mutations in chemically induced hamster buccal pouch carcinomas

Well-differentiated squamous cell carcinomas were induced in hamster buccal pouch epithelium by twice weekly topical applications of N-methyl-N-benzylnitrosamine (MBN) or 7,12-dimethylbenz[a]anthracene (DMBA) over a period of 15 weeks. Each of the 22 tumors induced (14 MBN and eight DMBA) were evaluated by single-strand conformation polymorphism and DNA sequencing to identify mutations in conserved exons (E5-E8) of the p53 tumor suppressor gene and codons 12/13 and 61 of Ha-ras. In addition, Northern blot analysis of 10 MBN tumors and five DMBA tumors was performed to determine whether the mdm-2 gene was overexpressed, p53 mutations were detected in five of 14 (35%) MBN-induced carcinomas and in two of eight (25%) DMBA-induced carcinomas. Ha-ras mutations were detected in three of 14 (21%) MBN-induced carcinomas and in three of eight (37%) DMBA-induced carcinomas. One MBN-induced carcinoma exhibited a mutation in both the p53 and Ha-ras genes. The majority (five of seven of p53/Ha-ras mutations induced by MBN were G->A transitions and two of these occurred at hamster p53 codon 248, which corresponds to human p53 codon 245, a known mutational tumor 'hot spot'. A->T transversion at Ha-ras codon 61 accounted for three of five (60%) DMBA-induced mutations. There was no evidence of mdm-2 overexpression in any of the tumors evaluated. Overall, the results provide additional support for the validity of the hamster buccal pouch model of oral carcinogenesis, as applied to sequential cellular and molecular analysis and cancer chemoprevention studies.

Multiple genetic alterations in hamster pancreatic ductal adenocarcinomas

Pancreatic ductal adenocarcinomas induced in the Syrian golden hamster (SGH) by N-nitrosobis(2-oxopropyl)amine share many similarities with the human disease, including mutations of the K-ras oncogene. In vitro carcinogenesis studies with immortal SGH pancreatic duct cells indicate that neoplastic transformation in this system can occur without mutational inactivation of p53 suppressor gene. In this study we extend the genetic analysis of the in vivo SGH model to increase the number of cases analyzed for the status of K-ras and to determine further the spectrum of alterations involved; we have studied the status of the p53, DCC, and Rb-1 suppressor genes and the status of the mdm2 oncogene, which can involve p53 indirectly. The partial SGH-coding sequence of mdm2 and DCC was determined. K-ras mutation in the second position of codon 12 was present in 17 of 19 (90%) of tumors. Immunohistochemistry and single strand conformation polymorphism analysis showed no evidence of p53 mutation in 21 tumors. RNase protection assays showed overexpression of mdm2 in 5 of 19 (26%) tumors. Semiquantitative reverse transcription-PCR analysis showed a complete or partial loss of DCC expression in 10 of 19 (53%) neoplasms and of Rb-1 (42%) expression in 8 of 19 tumors when compared to matched controls. Deregulation of these genes appears to be significant in SGH pancreatic carcinogenesis as indicated by their frequencies. However, the fact that 6 tumors showed either only a K-ras mutation or the absence of alterations of the 5 genes analyzed indicates that additional as yet unstudied or unknown genes are also involved in SGH pancreatic duct carcinogenesis.

Iatrogenic hyponatremia: a cause of death following pediatric tonsillectomy

Death following pediatric tonsillectomy is very rare. If deaths occur, they are most commonly due to bleeding or aspiration. In this presentation, we would like to illustrate another potentially lethal complication following the pediatric tonsillectomy, iatrogenic hyponatremia. We have encountered 3 patients who have developed post-operative hyponatremia. This has resulted in 2 deaths. The third patient was successfully treated and developed no permanent sequela. We will discuss the etiology and pathophysiology of post-operative hyponatremia including guidelines for administering fluid and electrolytes intra-operatively and post-operatively. We expect that fatal post-operative hyponatremia can be avoided in the pediatric tonsillectomy patients.

Genomic p53 mutation in a chemically induced hamster pancreatic ductal adenocarcinoma

This study investigates possible alterations in exons 5 through 8 of the p53 gene and altered p53 protein expression in the Syrian golden hamster model of pancreatic ductal adenocarcinoma. In the Syrian hamster p53 sequence, 1469 base pairs are presented for the genomic regions surrounding exons 5 through 8, along with the primer sequences specific for the enzymatic amplification of the individual exons. Single-stranded conformation polymorphism was analyzed on the products obtained by enzymatic amplification of hamster genomic DNA extracted from 2 transplantable pancreatic ductal adenocarcinomas, 6 groups of N-methylnitrosourea (MNU)-treated pancreatic duct cells, and 17 MNU-induced pancreatic ductal adenocarcinomas. The two transplantable adenocarcinomas were a well-differentiated ductal adenocarcinoma established from a N-nitrosobis(2-oxopropyl)amine-induced tumor and a poorly differentiated ductal adenocarcinoma established from a spontaneous tumor. An altered mobility indicated a conformational change in the first part of exon 5 in the solid form of the well-differentiated ductal adenocarcinoma. Direct sequencing of the amplified product revealed an A-->C transversion in codon 135, which corresponds to codon 132 in the human p53 gene. A conformational change in exon 7 was observed in 1 of 6 MNU-treated cell samples, and none of the 17 resultant tumors. Direct sequencing confirmed a deletion of one C of the three in codon 263, which generates a frameshift mutation. No conformational change was observed in any other products. Positive staining with PAb240 or DO7 antibodies against human p53 or with an antibody generated in our laboratory against the hamster p53 fusion protein was observed only in the solid form of well-differentiated ductal adenocarcinoma and in rare cells scattered in 4 of 28 MNU-induced tumors analyzed. This study provides a system to analyze p53 gene alterations in the hamster and is the initial report of a specific p53 mutation in a hamster pancreatic ductal adenocarcinoma.