Darryl C. Tong

Effect of brief exposure to mitomycin C on cultured human nasal mucosa fibroblasts.

PURPOSE To observe the effect of mitomycin C (MMC) on cultured human nasal mucosa fibroblasts. METHODS Cultured human nasal mucosa fibroblasts were exposed to MMC (0.1-0.4 mg/ml) for 1 to 5 minutes. The viability of the fibroblasts was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay; DNA fragmentation (apoptosis) by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL); apoptotic percentage by flow cytometry; and morphology by light microscopy. RESULTS A portion of the fibroblasts survived the mitomycin treatment and showed evidence of regrowth within 2 to 3 days. These cells reached confluence in 5 to 7 days. The inhibition rates by MTT assay of 0.4 mg/ml MMC for 5-minute exposures was 31.3%. Dose-response effect was noted with the lower concentrations and shorter exposure times where the inhibition rates were lower (but not significantly so). DNA fragmentation was observed in fibroblasts 24 hours after MMC exposure (0.4 mg/ml) for 5 minutes compared with normal control. The apoptotic rate of fibroblasts treated by 0.4 mg/ml MMC was significantly higher than the control (p < 0.05). CONCLUSIONS Short MMC exposure times have a variable cytotoxic effect and inhibit proliferation of cultured nasal mucosa fibroblasts. MMC also can induce apoptosis with a 5-minute exposure time. Therefore, it is possible that MMC has a complex effect in dacryocystorhinostomy.

Response of human oral epithelial cells to oxidative damage and the effect of vitamin E

Smoking and periodontal inflammation are various conditions with the potential to induce oxidative stress and thus DNA damage in the oral cavity. In cellular defense systems, vitamin E is considered the most powerful lipid-soluble antioxidant. To investigate whether oxygen-free radicals alter normal progression of the cell cycle and whether vitamin E prevents this damage, we exposed cultured normal human oral epithelial cells to hydrogen peroxide (H2O2) in the presence or absence of vitamin E. Two primary cell lines were analyzed for the presence of hydroxyl radical, cell cycle distribution and morphology. Each cell line received five treatments: control, ethanol only, vitamin E only, H2O2 only or vitamin E followed by H2O2. Degradation of hydroxyl radicals was detected by electron paramagnetic resonance analysis, cell cycle by flow cytometry and morphology by organotypic technique. Hydroxyl radicals were generated in H2O2-treated cells at an initial concentration, which decreased over a period of time. Cell cycle analysis showed that H2O2-treated cells differed from normal cells in that the percentage of cells in the G1 phase decreased markedly (34.3 vs. 61.2% in control) and the S phase increased (35.5 vs. 15.6% in control). Organotypic cultures treated with H2O2 demonstrated nuclear hyperchromatism, loss of maturation and prominent nucleoli, features consistent with premalignant epithelial transformation. In conclusion, our data suggest that H2O2 produced hydroxyl radicals and altered the cell cycle. Also, vitamin E may have the potential to reduce oxidative damage caused by hydroxyl radicals.

5-Fluorouracil-induced apoptosis in cultured oral cancer cells

Chemotherapy is commonly used to treat advanced oral squamous cell carcinoma (SCC) and is known to kill cancer cells through apoptosis. Our hypothesis states that 5-fluorouracil (5FU) also kills cultured oral epithelial cells through programmed cell death or apoptosis. Cultured oral cancer cells were exposed to an optimum dose of 20 mg/ml of 5FU. Cells were analyzed for changes in cell cycle distribution and induction of cell death including apoptosis. Normal control, human papilloma virus-immortalized (PP), ATCC SCC cell line (CA1) and two primary oral SCC cell lines (CA3 and -4) were studied. Inhibition of apoptosis by a pan-caspase inhibitor was used. SYTO 11 flow cytometry showed increased apoptosis in all 5FU-treated cell cultures compared to untreated controls. The results show biological variation in apoptotic response. CA1 had the lowest apoptotic rate of the cancer cell lines at 1.5%. Next lowest was CA3, followed by CA4 and PP. In addition, alteration in the G1 and S phase fractions were found. Untreated CA1 showed 28% G1, 53% S compared to 43% G1, and 40% S of treated. We investigated the pathway of apoptosis using the pan-caspase inhibitor IDN-1529 by methylthiazolyl diphenyl tetrazolium bromide (MTT) colorimetric analysis. Results showed mild inhibition of cell death when cells were incubated with 50 microM IDN-1529 for 24 h. This suggests a probable caspase-dependent apoptotic pathway. In conclusion, our data suggest that 5FU induces oral cancer cell death through apoptosis and that biological variation exists between normal and cancer cells and between different types of cancer cells themselves. Our data indicate that cultures of a useful in vitro model for chemosensitivity assays are possible. Our results also suggest a caspase-dependent pathway for chemocytotoxicity in oral SCC.

Radiolucent inflammatory jaw lesions: a twenty-year analysis.

AIM To determine the range and demographic and clinical features of radiolucent inflammatory jaw lesions. METHODOLOGY Histopathology reports were reviewed to identify radiolucent jaw lesions. There were no clinical exclusive criteria, and the samples represented a wide range of clinical presentation and treatment history from multiple providers. Data were analysed using SPSS. To evaluate concordance of clinical and histological diagnoses, the clinicians provisional diagnosis was compared with the final histopathological diagnosis. RESULTS A total of 17 038 specimens were reviewed; of these, 4983 (29.2%) were radiolucent jaw lesions, of which inflammatory lesions accounted for 72.8% (n = 3626). Periapical granulomas (59.7%) were the largest group followed by radicular cysts (29.2%). The mean age was 44 years (range 2-100 years), men and women were equally represented and the anterior maxilla was the most common site for the biopsied lesions. A provisional diagnosis was correct for only 48.3% of periapical granulomas and 36% of radicular cysts. CONCLUSIONS This study included all presentations of periapical radiolucent lesions and showed that the incidence of cystic change in periapical lesions of endodontic origin is high at approximately 30% of all inflammatory lesions. Notwithstanding the relative frequencies, demographics and location of radiolucent inflammatory lesions presenting in the New Zealand population are comparable to that of other populations. No inflammatory radiolucent lesion can be reliably accurately diagnosed from clinical presentation and/or radiographic appearance alone.

The mortality and cancer experience of New Zealand Vietnam war veterans: a cohort study.

Objectives The aim was to observe the patterns of mortality and cancer incidence in New Zealand Vietnam veterans. The objectives were to assess whether the patterns of disease observed were consistent with those associated with military service in Vietnam, and similar to the patterns identified in other groups of Vietnam veterans. Design A historical cohort study. Setting Veterans, identified from service records, with Vietnam service between 1964 and 1972. Participants Of the 3322 survivors of Vietnam service, we followed up 2783 (84%). Outcome measures Standardised mortality and incidence ratios (SMRs and SIRs, respectively) were calculated based on the number of deaths and cancer registrations observed, those expected being based on New Zealand national rates. Results All cause mortality was significantly reduced (SMR 0.85, 95% CI 0.77 to 0.94) and cancer incidence non-significantly increased (SIR 1.06, 95% CI 0.97 to 1.16). The risk of mortality from cancers of the head and neck (SMR 2.20, 95% CI 1.09 to 3.93); oral cavity pharynx and larynx (SMR 2.13, 95% CI 1.06 to 3.81) and the incidence of chronic lymphatic leukaemia (CLL) (SIR 1.91, 95% CI 1.04 to 3.20) were, however, significantly increased. Other lymphohaematopoietic disorders, specifically multiple myeloma and Hodgkin disease, showed non-significant mortality excesses, reflected by a similar increase in incidence. Conclusions Service in the Vietnam war was associated with defoliant herbicide exposure, including 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, picloram and cacodylic acid. Subsequent reviews of mechanistic, animal and epidemiological evidence led to certain conditions being deemed compensable. The pattern of mortality and cancer incidence is not at odds with the list of compensable conditions and consistent with that found in Australian veterans serving in the same area of Vietnam, but also consistent with smoking and the healthy soldier effect. In common with the Australian experience, this is the only veterans group to show a significant excess of CLL.

Concordance Between Clinical and Histopathologic Diagnoses of Oral Mucosal Lesions

PURPOSE To study the epidemiology of oral soft tissue lesions in New Zealand from 2002 to 2006 and to determine the concordance between the clinical diagnosis and the definitive histopathologic diagnosis achieved by general dental practitioners and by specialists. MATERIALS AND METHODS The details from biopsy referrals and the corresponding histopathologic reports of oral soft tissue lesions were recorded into a statistical software package, and the concordance between the clinical diagnosis and histopathologic diagnosis was determined for all the lesions. RESULTS Most biopsies were benign lesions, and both clinician groups achieved a high diagnostic concordance for these lesions. However, when considering all lesion types, the overall concordance for both groups was a moderate 50.6%, with little difference between specialists and general dental practitioners, although specialists were more accurate in diagnosing a malignant or premalignant lesion. CONCLUSIONS The clinical and histopathologic concordance achieved by oral health practitioners in New Zealand appears to be moderate.

Concurrent oral lichen planus and primary sclerosing cholangitis

Summary Four patients with concomitant oral lichen planus (OLP) and primary sclerosing cholangitis (PSC) are presented. Associations have been made between OLP and chronic liver disease, namely hepatitis C and primary biliary cirrhosis, but the aetiology and commonality between the diseases has yet to be confirmed. An immunological link is currently favoured. PSC may be a further association with OLP, possibly involving the immune system.

Influence of a pedicle flap design on acute postoperative sequelae after lower third molar removal

Pain, swelling, trismus, and alveolar osteitis often occur after removal of impacted third molar teeth. To minimize these complications a number of mucoperiosteal flap designs have been advocated, but, to date, a pedicle flap design has not been evaluated. In a randomized prospective split mouth study, 52 participants had bilateral symmetrically impacted mandibular third molars removed over two sessions. A buccal envelope or pedicle flap was randomly assigned to the left or right third molar site. Pre-and postoperative pain and swelling were recorded using a standardized visual analogue scale, trismus was measured as the maximum inter-incisal opening distance in millimetres and dry socket was assessed clinically. Greater continuous pain, pain on maximum opening, and oro-facial swelling were recorded with the pedicle flap design. Continuous pain resolved significantly faster with this flap design (p<0.05). Trismus was similar for both flap designs (p>0.05). Five cases of alveolar osteitis occurred with the envelope flap whilst no cases developed with the pedicle flap, but the incidence was too small for statistical analysis. The pedicle flap improved some aspects of postoperative pain experience and reduced the incidence of alveolar osteitis, but further investigation with a larger sample size is required to evaluate its significance.

Combat body armor and injuries to the head, face, and neck region: a systematic review

ABSTRACTThere has been a reported increase in combat-related head, face, and neck (HFN) injuries among service personnel wearing combat body armor (CBA) that have deployed to Iraq and Afghanistan. Modern ceramic plate CBA has decreased the incidence of fatal-penetrating injuries to the torso but offers no protection to the limbs and face which remain exposed to gunshot wounds and fragments from explosive devices. The aim of this review was to systematically summarize the literature reporting on HFN injuries sustained by combat personnel wearing CBA and to highlight recommendations for increased protection to the facial region. Three major contributing factors were identified with this proportional increase in HFN injuries, namely the increased survivability of soldiers because of CBA, fragments injuries from explosive devices, and the lack of protection to the face and limbs. There appears to be no evidence to suggest that by virtue of wearing CBA the likelihood of sustaining an HFN injury increases as su...There has been a reported increase in combat-related head, face, and neck (HFN) injuries among service personnel wearing combat body armor (CBA) that have deployed to Iraq and Afghanistan. Modern ceramic plate CBA has decreased the incidence of fatal-penetrating injuries to the torso but offers no protection to the limbs and face which remain exposed to gunshot wounds and fragments from explosive devices. The aim of this review was to systematically summarize the literature reporting on HFN injuries sustained by combat personnel wearing CBA and to highlight recommendations for increased protection to the facial region. Three major contributing factors were identified with this proportional increase in HFN injuries, namely the increased survivability of soldiers because of CBA, fragments injuries from explosive devices, and the lack of protection to the face and limbs. There appears to be no evidence to suggest that by virtue of wearing CBA the likelihood of sustaining an HFN injury increases as such, but a higher incidence of fragment injuries to the HFN region may be due to the more common use of improvised explosive devicess and other explosive devices. Further development of lightweight protection for the face is needed.

Damage control surgery and combat-related maxillofacial and cervical injuries: a systematic review

Damage control surgery involves rapid assessment, life-saving resuscitation, and abbreviated surgery for a patient with severe injuries. Traditionally the concept of damage control surgery has been restricted to penetrating abdominal injuries, but more recently it has been expanded to areas outside of the abdomen including the maxillofacial and neck regions. However, we know of little evidence that, when applied to injuries to the face and neck, it changes outcomes. We systematically reviewed published papers to identify those that discussed damage control in the context of combat-related trauma of the face and neck. We identified three papers that discussed the principles of managing combat-related maxillofacial injuries, all three of which were review articles that advocated the use of damage control principles in facial injuries either in isolation or as part of a multisystem approach. Anecdotal experience and opinion indicates that the concept of damage control is applicable when managing combat-related injuries of the face and neck, but no outcomes were confirmed. Further studies are required to validate the concept.