A giant peripheral ossifying fibroma of the maxilla with extreme difficulty in clinical differentiation from malignancy: a case report and review of the literature

BACKGROUND

Peripheral ossifying fibroma is a nonneoplastic inflammatory hyperplasia that originates in the periodontal ligament or periosteum in response to chronic mechanical irritation. Peripheral ossifying fibroma develops more commonly in young females as a solitary, slow-growing, exophytic nodular mass of the gingiva, no more than 2 cm in diameter. While various synonyms have been used to refer to peripheral ossifying fibroma, very similar names have also been applied to neoplastic diseases that are pathologically distinct from peripheral ossifying fibroma, causing considerable nomenclatural confusion. Herein, we report our experience with an unusual giant peripheral ossifying fibroma with a differential diagnostic challenge in distinguishing it from a malignancy.

CASE PRESENTATION

A 68-year-old Japanese male was referred to our department with a suspected gingival malignancy presenting with an elastic hard, pedunculated, exophytic mass 60 mm in diameter in the right maxillary gingiva. In addition to computed tomography showing extensive bone destruction in the right maxillary alveolus, positron emission tomography with computed tomography revealed fluorodeoxyglucose hyperaccumulation in the gingival lesion. Although these clinical findings were highly suggestive of malignancy, repeated preoperative biopsies showed no evidence of malignancy. Since even intraoperative frozen histological examination revealed no malignancy, surgical resection was performed in the form of partial maxillectomy for benign disease, followed by thorough curettage of the surrounding granulation tissue and alveolar bone. Histologically, the excised mass consisted primarily of a fibrous component with sparse proliferation of atypical fibroblast-like cells, partly comprising ossification, leading to a final diagnosis of peripheral ossifying fibroma. No relapse was observed at the 10-month follow-up.

CONCLUSIONS

The clinical presentation of giant peripheral ossifying fibromas can make the differential diagnosis from malignancy difficult. Proper diagnosis relies on recognition of the characteristic histopathology and identification of the underlying chronic mechanical stimuli, while successful treatment mandates complete excision of the lesion and optimization of oral hygiene. Complicated terminological issues associated with peripheral ossifying fibroma require appropriate interpretation and sufficient awareness of the disease names to avoid diagnostic confusion and provide optimal management.

Consideration of mouth opening when using positioning stents during radiotherapy for tongue cancer: a retrospective study

Background

The aim was to clarify the range of mouth opening required to minimize the development of oral mucositis on the palate while using a positioning stent during radiotherapy in patients with tongue cancer. A positioning stent is used to reduce the severity of oral mucositis; however, requirements for fabricating the device have not been standardized. In particular, the range of mouth opening required while using a stent to prevent radiation-induced oral mucositis has not been determined.

Materials and methods

We retrospectively analyzed medical records and computed tomography (CT) images of nine patients who had undergone radiotherapy for tongue cancer. Irradiation dose for the palate and range of mouth opening while using the positioning stent was calculated from CT images and the radiotherapy treatment planning program.

Results

The irradiation dose presented as medians and interquartile range (IQR) for the palate was 1.6 (IQR: 1.1-2.2) Gy with the use of the positioning stent and 37.2 (IQR: 17.5-44.1) Gy without the use of the positioning stent. The range of mouth opening was 19-37 [mean ± standard deviation (SD): 26 ± 5.6] mm, and it correlated with the attenuation amount of irradiation dose to the palate (r = 0.673, p = 0.0467). Regression equation was y = 0.21x + 19.

Conclusions

Our study may be useful for deriving the relationship between the attenuation amount of irradiation of the palate with the positioning stent and the amount of mouth opening required for this attenuation.

Antibody-like proteins that capture and neutralize SARS-CoV-2

To combat severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) and any unknown emerging pathogens in the future, the development of a rapid and effective method to generate high-affinity antibodies or antibody-like proteins is of critical importance. We here report high-speed in vitro selection of multiple high-affinity antibody-like proteins against various targets including the SARS-CoV-2 spike protein. The sequences of monobodies against the SARS-CoV-2 spike protein were successfully procured within only 4 days. Furthermore, the obtained monobody efficiently captured SARS-CoV-2 particles from the nasal swab samples of patients and exhibited a high neutralizing activity against SARS-CoV-2 infection (half-maximal inhibitory concentration, 0.5 nanomolar). High-speed in vitro selection of antibody-like proteins is a promising method for rapid development of a detection method for, and of a neutralizing protein against, a virus responsible for an ongoing, and possibly a future, pandemic.

Monitoring the build-up of hydrogen polarization for polarized hydrogen-deuteride (HD) targets with nuclear magnetic resonance (NMR) at 17 T

We report on the frozen-spin polarized hydrogen-deuteride (HD) targets for photoproduction experiments at SPring-8/LEPS. Pure HD gas with a small amount of ortho-H₂ (∼0.1%) and a very small amount of para-D₂ (∼0.001%) was liquefied and solidified by liquid helium. The temperature of the produced solid HD was reduced to about 30 mK with a dilution refrigerator. A magnetic field (17 T) was applied to the HD to grow the polarization with the static method. After the aging of the HD at low temperatures in the presence of a high-magnetic field strength for three months, the polarization froze. Almost all ortho-H₂ molecules were converted to para-H₂ molecules. Most remaining para-D₂ molecules were converted to ortho-D₂ molecules. The para-H₂ and ortho-D₂ molecules exhibited weak spin interactions with the HD. If the concentrations of the ortho-H₂ and para-D₂ were reduced appropriately at the beginning of the aging process, the aging time can be shortened. We have developed a new nuclear magnetic resonance (NMR) system to measure the relaxation times (T₁) of the ¹H and ²H nuclei with two frequency sweeps at the respective frequencies of 726 MHz and 111 MHz and succeeded in the monitoring of the polarization build-up at decreasing temperatures from 600 mK to 30 mK at 17 T. Automatic NMR measurements with the frequency sweeps enabled us to omit the use of a manual tuning circuit and to remove magnetic field sweeps with eddy current heat. This technique enables us to optimize the concentration of the ortho-H₂ and to efficiently polarize the HD target within a shortened aging time.

Design of photonic-crystal surface-emitting lasers with enhanced in-plane optical feedback for high-speed operation

Photonic-crystal surface-emitting lasers (PCSELs) use the two-dimensional (2D) resonance at the band-edge of a photonic crystal for lasing, and they feature various outstanding functionalities such as high-brightness lasing, arbitrary shaping of beam patterns and on-chip 2D beam steering. In this paper, to investigate the applicability of PCSELs for high-speed operation, we design PCSELs with enhanced in-plane optical feedback, which enable single-mode lasing inside a circular region the diameter of which is less than 10 µm. To realize a strong in-plane confinement of the lasing mode, we increase the one-dimensional coupling coefficients between counter-propagating waves through the careful design of the lattice points. We also introduce an in-plane heterostructure composed of two photonic crystals with different photonic bandgaps and utilize reflection at the boundary of the two photonic crystals in addition to the optical feedback at the band-edge of each photonic crystal. By using three-dimensional finite-difference time-domain method (3D-FDTD), we confirm that the proposed hetero-PCSELs can achieve single-mode lasing operation inside a 9-µm-diameter and possibly realize a 3-dB modulation bandwidth larger than 40 GHz.

Morphological Investigation of Residual Ridge in Japanese Edentulous Elderly for Fabrication of Edentulous Stock Tray

The objective of this study was to determine the size of the residual ridge in edentulous elderly Japanese persons for preparation of edentulous stock trays and clarify any correlations among the items measured. The participants comprised 74 patients requesting construction of a complete denture for the maxilla, mandible, or both. The length, width, and anterior and posterior height of the maxillary and mandibular residual ridge was measured on a prepared working model using a caliper. For each of the maxillary and mandibular edentulous residual ridges, correlations among measurement items were analyzed employing Pearson's correlation coefficient. In participants who were edentulous in both the maxilla and mandible, correlations between the maxillary and mandibular measurement items were analyzed employing Pearson's correlation coefficient. The results revealed that the mean maxillary length of the residual ridge was 55.21±4.07 mm, while mean mandibular length was 56.03±4.04 mm. The mean posterior width of the maxillary jaw was 48.79±4.14 mm, while that of the mandibular jaw was 57.33±3.24 mm. A strong correlation was found between the length and width of the residual ridge in both the maxilla and mandible, but no strong correlation was detected between the height in the anterior tooth region and any other item measured. These findings suggest that the size of any given item can be estimated by measuring either the length or width of the residual ridge when selecting a stock tray. We also propose that it is necessary to prepare stock trays with several different heights in the anterior tooth region, regardless of the length and width of the tray, or to adjust the length of the tray.

Relationship between masticatory function and frailty in community-dwelling Japanese elderly

BACKGROUND

Frailty likely results in impaired functioning, and frail individuals requiring long-term care have recently attracted the attention of researchers. In the oral health field, the number of elderly individuals who require intervention for retaining occlusion has been increasing, as has the number of remaining teeth and required prosthetic treatment. Additionally, the number of elderly with reduced masticatory function has also been increasing, and frailty is a suspected factor.

AIMS

The aim of this study is to clarify the relationship between frailty and masticatory function decline.

DESIGN

A cross-sectional study.

METHODS

A total of 747 participants (total mean age 73.6 ± 5.8 years old) underwent a comprehensive examination at the Tokyo Metropolitan Institute of Gerontology. Three masticatory functions were evaluated: maximum occlusal force, mixing ability, and self-reported chewing ability. Frailty was determined using all 25 questions of the Basic checklist developed by the Japanese Ministry of Health, Labour and Welfare, following the method reported by Satake et al. RESULTS: Binomial logistic analysis clarified the relationship between frailty and evaluation of each of the three masticatory functions. Significant correlations of pre-frailty or frailty with maximum occlusal force, mixing ability, and subjective chewing ability were observed.

CONCLUSION

All three masticatory functions (maximum occlusal force, mixing ability, and self-reported chewing ability) were associated with pre-frailty or frailty in community-dwelling Japanese elderly.

Maxillofacial prosthetic treatment factors affecting oral health-related quality of life after surgery for patients with oral cancer

STATEMENT OF PROBLEM

After oral cancer surgery, tissue defects can cause deformity and limited mobility, complicating many essential functions. For patients with mandibular, tongue, and oral floor defects, evidence regarding the effects of maxillofacial prosthetics on their oral health-related quality of life (OHRQoL) is lacking. Therefore, maxillofacial prosthetic reconstruction has been implemented with no clear treatment goals.

PURPOSE

The purpose of this clinical study was to identify factors affecting the improvement of OHRQoL by using maxillofacial prosthetic treatment after surgery to repair maxillary, mandibular, tongue, and oral floor defects.

MATERIAL AND METHODS

All individuals who agreed to maxillofacial prosthetics after surgery for oral cancer were enrolled. Oral function and OHRQoL were evaluated before maxillofacial prosthesis placement and 1 month after final adjustments. The oral functions evaluated included masticatory function, swallowing function, and articulatory function. The Oral Health Impact Profile (OHIP-J54) was used to evaluate OHRQoL. Factors affecting changes in the OHIP-J54 score for participants' background and oral functions before and after treatment were analyzed through logistic regression analysis (stepwise method).

RESULTS

Participants included 34 men and 16 women with an average age of 72.4 ±8.7 years. "Psychological discomfort" was correlated with the patient's sex and masticatory function. "Physical disability" was related to articulatory function. "Handicap" was related to the swallowing function. "Additional Japanese questions" were related to the patient's sex.

CONCLUSIONS

Participants' sex and their oral functions, including masticatory, swallowing, and articulatory functions, were associated with improved OHRQoL because of maxillofacial prosthetics after surgery for oral cancer.

Anti-infective control in human bronchiolar epithelial cells by mucin phenotypic changes following uptake of N-acetyl-L-cysteine

PURPOSE

Aspiration pneumonia is infection of the respiratory tract resulting from accumulation of sputum in the larynx. N-acetyl-L-cysteine (NAC) might regulate mucin (MUC) expression and activate inherent anti-infective system in bronchiolar epithelial cells after cellular uptake, and therefore, serve as the preventative agent for chronic lung disease including aspiration pneumonia. The purpose of this in vitro study was to evaluate the effect of uptake of NAC by human bronchiolar epithelial cells on bacterial infection and regulations of mucin expression in association with cellular redox status under co-culture with a representative pathogen for hospital- and community-acquired pneumonia, Streptococcus pneumoniae.

MATERIALS AND METHODS

Human bronchiolar epithelial cells preincubated with or without 20 mM NAC for 3 h were co-cultured with or without bacteria for 8 h and evaluated with respect to cellular redox balance, expressions of various types of MUC, proinflammatory cytokines and mediators, and bacterial infection state by biochemical, genetic, and immunofluorescent assays.

RESULTS

Markedly increased intracellular reactive oxygen species and oxidized glutathione levels plus increased release and expression of proinflammatory cytokines and mediators were observed in cells co-cultured with bacteria. These bacteria-induced cellular redox disturbance and proinflammatory events were prevented and alleviated by pretreatment with NAC. Cells co-cultured with bacteria did not increase expression of anti-infective membranous MUC4 but exhibited increases in gel-forming MUC5AC expression and bacterial infection. However, NAC-pretreated cells avoided bacterial infection along with enhancement of MUC4, but not MUC5AC, expression.

CONCLUSION

Uptake of NAC by human bronchiolar epithelial cells prevented bacterial infection and upregulated membranous, but not gel-forming, MUC expression along with the increase in intracellular antioxidant level under co-culture conditions with S. pneumoniae.

Ultraviolet-C irradiation to titanium implants increases peri-implant bone formation without impeding mineralization in a rabbit femur model

OBJECTIVES

Volume and bone quality of peri-implant supporting bone, in particular, at implant neck region, as well as bone-implant contact ratio, is important for long-term stability of implants. Ultraviolet-C (UVC) irradiation is known to enhance the osseointegration capability of titanium implants. However, the histological determination was performed only on a rat model, but not pre-clinical animal model such as a rabbit model. The purpose of this study was to determine the effects of UVC irradiation on titanium implants on the volume and mineral density of peri-implant supporting bone formation in a rabbit femur model.

MATERIALS AND METHODS

Acid-etched pure titanium screw implants with or without 3 mW/cm2 UVC irradiation for 48 h were placed in rabbit femur diaphyses. Peri-implant bone tissue formation was analyzed at 3 and 8 weeks post-operatively by histology and micro-CT-based bone morphometry after calibration with hydroxyl apatite phantoms.

RESULTS

UVC pre-irradiated implants accumulated a higher density of cells and thicker and longer bone tissue attachments that continued into the inner basic lamellae of the surface of existing cortical bone at 3 and 8 weeks than the implants without irradiation. Although the bone mineral density around both implants was equivalent to that of the existing cortical bone, bone volume was greater with UVC pre-irradiation in two-thirds or more of the apical region throughout the observation period.

CONCLUSIONS

These results indicate that UVC treatment increased the volume of cortical-like bone tissue in the coronal region of titanium implants without deterioration of bone mineral density.

Specific ultraviolet-C irradiation energy for functionalization of titanium surface to increase osteoblastic cellular attachment

Purpose

The objective of this in vitro study was to examine the influence of the total energy of ultraviolet-C preirradiation on the number and morphology of osteoblastic cells attached to turned or acid-etched titanium surfaces, and physicochemical properties of the surface.

Materials and methods

Rat bone marrow-derived osteoblasts were incubated with turned or acid-etched titanium disks preirradiated with ultraviolet-C at 1 or 3 mW/cm2, resulting in total energies of 10, 100, 250, 400, 500, 600, 750, or 1000 J/cm2. Osteoblast attachment to the surface was evaluated using the WST-1 assay. Physicochemical changes of the titanium were evaluated by measuring water wettability and X-ray photoelectron spectroscopy analysis.

Results

Number of attached cells was greater on turned or acid-etched surface preirradiated with 500 or 750 J/cm2 of 3 mW/cm2 ultraviolet-C than on the nonirradiated surface, respectively. However, the further irradiation energy did not increase the numbers on both types of the surfaces. These phenomena were also seen on the surfaces preirradiated at different ultraviolet-C intensities. Ultraviolet-C irradiation induced superhydrophilicity on both types of surface even with the less irradiation energy. The amount of carbon on ultraviolet-C preirradiated titanium surfaces decreased gradually with an increase in the total irradiation energy.

Conclusion

Specific ultraviolet-C energy used to irradiate turned or acid-etched surfaces increased the number of osteoblastic cells attached to each of the surface. This was canceled by overirradiation, despite maintenance of both the acquired superhydrophilicity and the accompanying reduction in carbon on each surface.

Bone integration capability of alkali- and heat-treated nanobimorphic Ti-15Mo-5Zr-3Al

The role of nanofeatured titanium surfaces in a number of aspects of in vivo bone-implant integration, and, in particular, their potential advantages over microfeatured titanium surfaces, as well as their specific contribution to osteoconductivity, is largely unknown. This study reports the creation of a unique nanobimorphic titanium surface comprised of nanotrabecular and nanotuft-like structures and determines how the addition of this nanofeature to a microroughened surface affects bone-implant integration. Machined surfaces without microroughness, sandblasted microroughened surfaces, and micro-nano hybrid surfaces created by sandblasting and alkali and heat treatment of Ti-15Mo-5Zr-3Al alloy were subjected to biomechanical, interfacial and histological analyses in a rat model. The presence of microroughness enabled accelerated establishment of biomechanical implant fixation in the early stages of healing compared to the non-microroughened surfaces; however, it did not increase the implant fixation at the late stages of healing. The addition of nanobimorphic features to the microroughened surfaces further increased the implant fixation by as much as 60-100% over the healing time. Bone area within 50 μm of the implant surface, but not beyond this distance, was significantly increased by the presence of nanobimorphic features. Although the percentage of bone-implant contact was also significantly increased by the addition of nanobimorphic features, the greatest improvement was found in the soft tissue intervention between the bone and the implant, which was reduced from >30% to <5%. Mineralized tissue densely deposited with calcium-binding globular proteins was observed in an extensive area of nanobimorphic surfaces after biomechanical testing. This study clearly demonstrates the nanofeature-enhanced osteoconductivity of titanium by an alkali- and heat-treated nanobimorphic surface compared to that by microfeatured surfaces, which results not only in an acceleration but also an improvement of bone-implant integration. The identified biological parameters that successfully detect the advantages of nanofeatures over microfeatures will be useful in evaluating new implant surfaces in future studies.

Nanometer-thin TiO₂ enhances skeletal muscle cell phenotype and behavior

Background

The independent role of the surface chemistry of titanium in determining its biological properties is yet to be determined. Although titanium implants are often in contact with muscle tissue, the interaction of muscle cells with titanium is largely unknown. This study tested the hypotheses that the surface chemistry of clinically established microroughened titanium surfaces could be controllably varied by coating with a minimally thin layer of TiO₂ (ideally pico-to-nanometer in thickness) without altering the existing topographical and roughness features, and that the change in superficial chemistry of titanium is effective in improving the biological properties of titanium.

Methods and results

Acid-etched microroughened titanium surfaces were coated with TiO₂ using slow-rate sputter deposition of molten TiO₂ nanoparticles. A TiO₂ coating of 300 pm to 6.3 nm increased the surface oxygen on the titanium substrates in a controllable manner, but did not alter the existing microscale architecture and roughness of the substrates. Cells derived from rat skeletal muscles showed increased attachment, spread, adhesion strength, proliferation, gene expression, and collagen production at the initial and early stage of culture on 6.3 nm thick TiO₂-coated microroughened titanium surfaces compared with uncoated titanium surfaces.

Conclusion

Using an exemplary slow-rate sputter deposition technique of molten TiO₂ nanoparticles, this study demonstrated that titanium substrates, even with microscale roughness, can be sufficiently chemically modified to enhance their biological properties without altering the existing microscale morphology. The controllable and exclusive chemical modification technique presented in this study may open a new avenue for surface modifications of titanium-based biomaterials for better cell and tissue affinity and reaction.

Effects of pico-to-nanometer-thin TiO2 coating on the biological properties of microroughened titanium

The independent, genuine role of surface chemistry in the biological properties of titanium is unknown. Although microtopography has been established as a standard surface feature in osseous titanium implants, unfavorable behavior and reactions of osteogenic cells are still observed on the surfaces. To further enhance the biological properties of microfeatured titanium surfaces, this study tested the hypotheses that (1) the surface chemistry of microroughened titanium surfaces can be controllably varied by coating with a very thin layer of TiO(2), without altering the existing topographical and roughness features; and (2) the change in the surface chemistry affects the biological properties of the titanium substrates. Using a slow-rate sputter deposition of molten TiO(2) nanoparticles, acid-etched microroughened titanium surfaces were coated with a TiO(2) layer of 300-pm to 6.3-nm thickness that increased the surface oxygen levels without altering the existing microtopography. The attachment, spreading behavior, and proliferation of osteoblasts, which are considered to be significantly impaired on microroughened surfaces compared with relatively smooth surfaces, were considerably increased on TiO(2)-coated microroughened surfaces. The rate of osteoblastic differentiation was represented by the increased levels of alkaline phosphatase activity and mineral deposition as well as by the upregulated expression of bone-related genes. These biological effects were exponentially correlated with the thickness of TiO(2) and surface oxygen percentage, implying that even a picometer-thin TiO(2) coating is effective in rapidly increasing the biological property of titanium followed by an additional mild increase or plateau induced by a nanometer-thick coating. These data suggest that a super-thin TiO(2) coating of pico-to-nanometer thickness enhances the biological properties of the proven microroughened titanium surfaces by controllably and exclusively modulating their surface chemistry while preserving the existing surface morphology. The improvements in proliferation and differentiation of osteoblasts attained by this chemical modification is of great significance, providing a new insight into how to develop new implant surfaces for better osseointegration, based on the established microtopographic surfaces.

Influence of palatal surface shape of dentures on food perception

The purpose of this study was to clarify the influence of the palatal surface shape of dentures on food perception. Eighteen healthy dentulous subjects (mean age, 24 years) were investigated. Four types of experimental plate were used: (i) a tailor-made plate, (ii) an average-model plate, (iii) a smooth plate, and (iv) a wrinkle plate. Test foods consisted of Bavarian cream cubes containing one to three mustard seeds and six raw carrot pieces of different shapes. Bavarian cream cubes with three seeds were used for analysis. Other foods were used as dummy foods. Subjects were required to wear experimental plates and press test foods placed on the anterior area of the tongue against the experimental plates. We measured time required to perceive number of spherical bodies, rate of correct answers, and level of perception with each type of experimental plate using a 100-mm visual analogue scale. The results showed a significant difference in response time between the average-model plate and the other experimental plates, with response time longest for the average-model plate. On the other hand, no significant differences in rate of correct answers regarding number of spherical bodies or level of perception were found among the experimental plates. When incisive papilla, palatine suture and palatal rugae based on the standard Japanese shape were replicated on the palatal surface of the plates, the time required for food perception during ingestion was prolonged in comparison to plates with other palatal surface shapes.

Response of Merkel cells in the palatal rugae to the continuous mechanical stimulation by palatal plate

The aim of the present study was to investigate the responses of Merkel cells that are numerous in the palatine rugae, due to the continuous mechanical stimulation exerted by the palatal plate. Forty golden hamsters were used in this experiment. The palatal plate was made of adhesive resin and it was set on the palate of the animal. To exert a continuous pressure, a 0.8 mm elevation on the internal surface of the palatal plate was created at the middle portion of the fourth palatine ruga. Thereafter, the number of Merkel cells in the mucosa was calculated by immunohistochemical observation. Morphological changes of Merkel cells were examined by electron microscopy. There was significant difference among the control and any of the treated groups on the number of CK20 positive Merkel cells (p < 0.05) and that numbers were decreased at the sites where continuous mechanical stimulation was exerted. Degeneration of the cytoplasm mitochondria and nerve endings, and a decrease in both the number of neurosecretory granules and cytoplasmic processes were observed. Furthermore, the presence of nuclear chromatin aggregation and fragmentation was recognized. The continuous mechanical stimulation by the palatal plate affected the responses of Merkel cells and nerve endings, thus inducing a decrease in the number of Merkel cells. A portion of these changes was also associated with the expression of apoptosis.

Effect of palate covering on bolus-propulsion time and its contributory factors

The aim of this study was first to investigate whether the covering of the palatal mucosa with a denture base affects or not the bolus-propulsion time, and second if there was such an effect then investigate the possible contributory factors which have influence on the propulsion time. The propulsion time was measured in 21 young normal edentulous subjects under five different conditions: a complete palatal covering, non-covered palate, anterior palatal covering, posterior palatal covering and surface anaesthetized palate. As possible contributory factors palatal morphometric parameters, as well as tongue pressure were also measured. The data were analysed on the following way: changes when the palate was complete covered and non-covered, effects of sensation reduction after topic anaesthesia, effects of differences in the covering site, effects of palatal morphometric parameters and effects of tongue pressure. Ten subjects exhibited significant differences in the propulsion time when comparing the data between the complete palatal covering and the non-covered palate condition (change group). Eleven subjects did not show changes (unchanged group). Effects in the propulsion time were also recognized with posterior palatal covering-palate and superficially anaesthetized palate. With regard to the tongue pressure, significant differences during swallowing were observed. These results indicated that the bolus propulsion time into the oropharynx was affected by the palatal covering in some subjects. Moreover, the sensation in the posterior region of the hard palate, as well as the tongue pressure were also factors which affected the propulsion time during swallowing.

Characterization of the peri-implant epithelium in hamster palatine mucosa: Behavior of Merkel cells and nerve endings

The purpose of this study was to investigate the relationship between Merkel cells and nerve elements during tissue regeneration after receiving dental implants. Golden hamsters were divided into 3 groups and titanium alloy implants were fixed in their left-side maxilla through the third palatine rug. Animals were sacrificed at 1, 2, 3, 4, 5, 6, and 7 days after the implantation and tissues were characterized at the immunohistochemical and morphological levels. CK 20 and PGP 9.5 antibodies which react with Merkel cells and nerve fibers were used. Immunohistochemically, no CK 20-positive Merkel cells were seen in the peri-implant epithelium throughout the 7 days. However, starting at day 4, PGP 9.5-positive nerve fibers appeared in the connective tissue, and by day 7, nerve fibers had invaded the more superficial layer of the peri-implant epithelium compared to the mucosa removal control group. At the electron microscopic level, the intercellular spaces of the regenerating epithelium in the mucosa removal control group were small. In contrast, intercellular spaces of the peri-implant epithelium tended to be wide and regenerating nerve fibers invaded those intercellular spaces. In both the mucosa removal control group and the implantation group, the basal lamina and connective tissues regenerated completely. However, clear Merkel cells containing neurosecretory granules were not observed. Taken together, our results indicate that Merkel cells in the hamster palatine mucosa do not regenerate in the peri-implant epithelium. However, regenerative nerve fibers seem to play essential roles as part of the defense and sensory systems around the peri-implant epithelium to compensate for the weakened defense mechanism.

Glutathione S-transferase polymorphisms: susceptibility to migraine without aura

Migraine is considered to be a polygenic multifactorial disease with various environmental and genetic etiologies. We investigated glutathione S-transferase (GST) P1 Ile(105)Val, T1 and M1 polymorphisms in 174 Japanese headache sufferers and 372 Japanese controls. The headache group consisted of 38 cases of migraine with aura, 95 migraine without aura (MWOA) and 41 tension-type headache sufferers. The M1 homozygous deletion genotype was significantly higher in MWOA (64%) compared with controls (46%; p < 0.01; odds ratio = 2.18, 95% confidence interval: 1.32-3.61, adjusted for age and gender). In a comparison of the current smokers, the M1 null frequencies in MWOA were further increased. GSTM1 may be one of the genetic risk factors for MWOA in the Japanese population.

Leukocyte mitochondrial DNA A to G polymorphism at 11084 is not a risk factor for Japanese migraineurs

Mitochondrial dysfunction has been reported in patients with migraine. We investigated leukocyte mitochondrial DNA 11084 A to G polymorphism in 166 Japanese migraineurs and 483 Japanese controls. The migraine group consisted of 43 patients suffering from migraine with aura (MWA) and 123 from migraine without aura (MOA). The frequency of the transition was 7.2% (12/166) in the migraine group and 7.3% (35/483) in the controls. The frequency of the transition was 4.7% in MWA and 8.1% in MOA. There was no significant difference among the groups (chi-square test). The mitochondrial DNA 11084 A to G transition was more common in Japanese subjects than reported in Caucasians; however, this polymorphism is not a genetic risk factor for migraine in Japanese patients.

Cold-stimulated increase in a regulatory subunit of cAMP-dependent protein kinase in human hepatoblastoma cells

Although cold-stress responses in bacteria and plants have been well studied and hypothermic conditions are used in clinical treatments, there has been little investigation of cold-stress responses in human cells, and there has been no report on the involvement of signal transduction modulators in the cold-stress response in human cells. We therefore investigated alterations in the expression of genes involved in the signal transduction system and the mechanisms of cold-stimulated increases in the expression of genes in human hepatoblastoma (HepG2) cells. Using a cDNA expression array method, we found that a transcript encoding a regulatory subunit Ibeta (RIbeta) of cyclic AMP-dependent protein kinase (PKA) was increased in cold-stressed cells. Western blot analysis revealed that the amount of PKA RIbeta protein was increased by cold treatment, while that of a PKA catalytic subunit (C) was unchanged. The protein level of PKA RIbeta was increased in cells treated with low concentrations of actinomycin D, whereas that of PKA C was not, implying that the increase was caused by the suppression of transcription at low temperatures. In addition, degradation of the PKA RIbeta protein was not stimulated by cold treatment, unlike that of the PKA C protein. The results suggest that signal transduction through PKA also participates in cold-stress responses in human cells and that multiple mechanisms are involved in the increase in the level of the PKA RIbeta protein.

Genetic changes induced in human cells in Space Shuttle experiment (STS-95)

BACKGROUND

Results of past space experiments suggest that the biological effect of space radiation could be enhanced under microgravity. To assess the radiation risk for humans during long-term spaceflight, it is very important to clarify whether human cells exhibit a synergistic effect of radiation and microgravity.

HYPOTHESIS

If significant synergism occurs in human cells, genetic changes induced during spaceflight may be detected by using human tumor HCT-116 cells which are hypermutable due to a defect in the DNA mismatch repair system.

METHODS

Cultured HCT-116 cells were loaded on the Space Shuttle Discovery (STS-95) and grown during the 9-d mission. After landing, many single-cell clones were isolated, microsatellite repetitive sequences in each clone were amplified by PCR, and mutations in the microsatellite loci were detected as changes in the length of PCR fragments. Mutation frequencies of ouabain-resistant phenotype were also analyzed.

RESULTS

The frequencies of microsatellite mutations as well as ouabain-resistant mutations in the flight sample were similar to those of the ground control samples. Some cells were treated in space with bleomycin which mimics the action of radiation, but the frequencies of microsatellite mutations were not significantly different between the flight and the ground control samples.

CONCLUSION

Under the present flight conditions, neither space radiation (about 20 mSv during this mission) nor microgravity caused excess mutations in human cells.

The Y chromosome in the liverwort Marchantia polymorpha has accumulated unique repeat sequences harboring a male-specific gene

The haploid liverwort Marchantia polymorpha has heteromorphic sex chromosomes, an X chromosome in the female and a Y chromosome in the male. We here report on the repetitive structure of the liverwort Y chromosome through the analysis of male-specific P1-derived artificial chromosome (PAC) clones, pMM4G7 and pMM23-130F12. Several chromosome-specific sequence elements of approximately 70 to 400 nt are combined into larger arrangements, which in turn are assembled into extensive Y chromosome-specific stretches. These repeat sequences contribute 2-3 Mb to the Y chromosome based on the observations of three different approaches: fluorescence in situ hybridization, dot blot hybridization, and the frequency of clones containing the repeat sequences in the genomic library. A novel Y chromosome-specific gene family was found embedded among these repeat sequences. This gene family encodes a putative protein with a RING finger motif and is expressed specifically in male sexual organs. To our knowledge, there have been no other reports for an active Y chromosome-specific gene in plants. The chromosome-specific repeat sequences possibly contribute to determining the identity of the Y chromosome in M. polymorpha as well as to maintaining genes required for male functions, as in mammals such as human.

Effects of 5-HT2 and 5-HT3 receptors on the modulation of nociceptive transmission in rat spinal cord according to the formalin test

We used the formalin test to clarify the 5-hydroxytryptamine (5-HT) receptor subtypes involved in the modulation of spinal nociceptive transmission in rats. Intrathecal administration of a 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)-tetraline (8-OH-DPAT; 1, 10, and 30 microg), or a 5-HT1B receptor agonist, 1, 4-dihydro-3-(1, 2, 3, 6-tetrahydro-4-pyridinyl)-5H-pyrrol (3, 2-b) pyridin-5-one (CP 93129; 1 and 10 microg), produced no significant change in the number of flinches. A 5-HT(2) receptor agonist, (+/-)-2, 5-dimethoxy-4-iodoamphetamine (DOI; 10, 30, and 100 microg), and a 5-HT3 receptor agonist, 2-methyl-5-HT (100 and 300 microg), produced dose-dependent decreases in the number of flinches in phases 1 (1 to 6 min) and 2 (10 to 61 min) of the test. The antinociceptive effects of DOI and 2-methyl-5-HT were antagonized by intrathecal pretreatment with a 5-HT2 receptor antagonist, ketanserin, and a 5-HT3 receptor antagonist, 3-tropanyl-3, 5-dichlorobenzoate (MDL-72222), respectively. These results suggest that 5-HT2 and 5-HT3 receptors in the spinal cord mediate antinociception to chemical stimuli.

Different susceptibility of each L-myc genotype to esophageal cancer risk factors

To understand the relationship between the L-myc genotypes and esophageal cancer risk, a polymerase chain reaction-based restriction fragment length polymorphism analysis was performed on 91 Japanese patients with esophageal cancer and 241 non-cancer outpatients. No significant difference in the distribution of genotypes was observed between patients and controls; 18.7% LL genotype, 56.0% LS and 25.3% SS among patients, and 24.5%, 55.6% and 19.9%, respectively, among controls. Frequency of the s-allele in patients (0.533) was slightly higher than in controls (0.477), but the difference was not statistically significant. However, the odds ratios (ORs) for smoking or heavy drinking were markedly higher in SS and LS genotypes than in LL genotype; age-sex-adjusted ORs for smoking was 7.57 in the SS genotype, 6.40 in the LS genotype and 1.77 in the LL genotype. Age-sex-adjusted ORs for heavy drinking were 19.78, 18.20 and 7.40, respectively. The age-sex-adjusted ORs for both factors combined were 12.77, 18.45 and 1.44, respectively. These results suggested that the L-myc polymorphism might modify the effects of lifestyle factors on esophageal cancer risk.

Effect of sodium tauroursodeoxycholate on phalloidin-induced cholestasis in rats

We investigated the therapeutic effect of tauroursodeoxycholate on phalloidin-induced cholestasis in rats. Intrahepatic cholestasis was induced by administration of phalloidin (500 microg/kg, i.p.) for 7 days. From the day of the last phalloidin injection, tauroursodeoxycholate (60-360 micromol/kg) was given intravenously twice a day for 4 days. On the next day after the last tauroursodeoxycholate administration, bile flow, serum biochemical parameters and biliary lipid excretion rates were determined. Tauroursodeoxycholate significantly suppressed the decrease in bile flow and increases in serum alkaline phosphatase, leucine aminopeptidase and glutamic pyruvic transaminase activities, cholesterol, phospholipid and bile acid concentrations observed in phalloidin-induced cholestasis in rats. Furthermore, tauroursodeoxycholate significantly improved the biliary cholesterol and phospholipid excretion rates in phalloidin-induced cholestasis in rats. These results demonstrate the usefulness of tauroursodeoxycholate as a therapeutic agent in intrahepatic cholestasis.

Polymorphism and allelic loss at the AS3 locus on 13q12-13 in esophageal squamous cell carcinoma

Our previous studies of esophageal squamous cell carcinoma (ESC) revealed that frequent loss of heterozygosity (LOH) on 13q12-13 was associated with lymph node metastasis. These results suggest that 13q12-13 may harbor a tumor suppressor gene which regulates lymph node metastasis. Recently, a new tumor suppressor candidate, AS3, was identified in this region. We therefore examined AS3 alterations by PCR-SSCP and RT-PCR. Although polymorphisms were found in exon 10 and introns 21, 23, 25 and 29, a possible tumor specific mutation in exon 6 was identified in only one of 31 ESC-derived cell lines, indicating that the remaining allele of AS3 was rarely inactivated by mutational events. Interestingly, ESC patients with rare alleles frequently exhibited lymph node metastasis. These results suggest that polymorphic variation and LOH at the AS3 locus might be associated with lymph node involvement in ESC.

Ccm1, a regulatory gene controlling the induction of a carbon-concentrating mechanism in Chlamydomonas reinhardtii by sensing CO2 availability

Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a set of genes for a carbon-concentrating mechanism (CCM) to acclimate to CO2-limiting conditions. This acclimation is modulated by some mechanisms in the cell to sense CO2 availability. Previously, a high-CO2-requiring mutant C16 defective in an induction of the CCM was isolated from C. reinhardtii by gene tagging. By using this pleiotropic mutant, we isolated a nuclear regulatory gene, Ccm1, encoding a 699-aa hydrophilic protein with a putative zinc-finger motif in its N-terminal region and a Gln repeat characteristic of transcriptional activators. Introduction of Ccm1 into this mutant restored an active carbon transport through the CCM, development of a pyrenoid structure in the chloroplast, and induction of a set of CCM-related genes. That a 5,128-base Ccm1 transcript and also the translation product of 76 kDa were detected in both high- and low-CO2 conditions suggests that CCM1 might be modified posttranslationally. These data indicate that Ccm1 is essential to control the induction of CCM by sensing CO2 availability in Chlamydomonas cells. In addition, complementation assay and identification of the mutation site of another pleiotropic mutant, cia5, revealed that His-54 within the putative zinc-finger motif of the CCM1 is crucial to its regulatory function.

Mismatch repair and microsatellite instability in esophageal cancer cells

Using in vitro mismatch repair (MMR) assay, we have identified 3 of 22 esophageal cancer cell lines exhibiting reduced MMR activity. By means of gel-shift assay, decreased binding ability to GT mismatch and CA loop was observed in these 3 cell lines. However, we could not find any mutations in the hMSH2, hMSH3 and hMSH6 genes, the protein products of which exhibit mismatch binding activity in human cells. In addition, when using antibodies against 5 MMR-related proteins (hMSH2, hMSH3, hMSH6, hPMS2 and hMLH1), no aberrant expression was detected in any of them. When we examined 9 microsatellite loci in endogenous genomic DNA, these 3 esophageal cancer cell lines, deficient in MMR, did not exhibit microsatellite instability. However, when we examined the repetitious sequence on exogenous plasmid DNA which was introduced into these 3 esophageal cancer cells, the results suggested that MMR deficiency in esophageal cancer cells could result in moderate instability of the exogenous sequence.

Antiallodynic effect of intrathecally administered 5-HT(2) agonists in rats with nerve ligation

We examined the antiallodynic effect of intrathecally administered serotonin receptor agonists including 5-HT(1A), 5-HT(1B), 5-HT(2) and 5-HT(3) receptor subtypes in a rat model using spinal nerve ligation at L5 and L6. Administration of the 5-HT(2) receptor agonist, alpha-methyl-5-hydroxytryptamine maleate (alpha-m-5-HT; 3-100 microg) or (+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI; 10-100 microg), showed dose-dependent antiallodynic actions with no associated motor weakness. The antiallodynic action of alpha-m-5-HT was more potent than that of DOI. The effects of 5-HT(2) agonists on tactile allodynia were reversed by intrathecal pretreatment with the selective 5-HT(2) antagonist ketanserin and with the mixed 5-HT(1) and 5-HT(2) antagonist methysergide. Neither the mixed 5-HT(1A) and 5-HT(1B) antagonist cyanopindolol nor the selective 5-HT(3) antagonist MDL72222 attenuated antiallodynic effects induced by 5-HT(2) agonists. In contrast, the selective 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)-tetralin hydrobromide (8-OH-DPAT; 1-50 microg), the 5-HT(1B) agonist 5-methoxy-3-(1,2,5,6-tetrahydro-4-pyridinil)-1H-indol (RU-24969; 10-100 microg) and the 5-HT(3) agonist 2-methyl-5-hydroxytryptamine maleate (2-m-5-HT; 30-300 microg) all lacked significant antiallodynic action with intrathecal administration. These results indicate that the 5-HT(2) receptor plays an essential role in spinal suppression of neuropathic pain by 5-HT.

Clock genes outside the suprachiasmatic nucleus involved in manifestation of locomotor activity rhythm in rats

Chronic treatment of methamphetamine (MAP) in rats desynchronized the locomotor activity rhythm from the light-dark cycle. When the activity rhythm was completely phase-reversed with respect to a light dark-cycle, 24 h profiles were examined for the clock gene (rPer1, rPer2, rBMAL1, rClock) expressions in several brain structures by in situ hybridization, and for the pineal as well as plasma melatonin levels. In the MAP-treated rats, the rPer1 expression in the suprachiasmatic nucleus (SCN) showed a robust circadian rhythm which was essentially identical to that in the control rats. Circadian rhythms in pineal as well as plasma melatonin were not changed significantly in the MAP-treated rats. However, robust circadian rhythms in the rPer1, rPer2 and rBMAL1 expressions detected in the caudate-putamen (CPU) and parietal cortex were completely phase-reversed in the MAP-treated rats, compared with those in the control rats, indicating desynchronization from the SCN rhythm. Such desynchronization was not observed in the circadian rhythms of clock gene expression in the nucleus accumbens and cingulate cortex. The circadian rClock expression rhythm in the MAP-treated rats was not phase-reversed in the CPU and parietal cortex. These findings indicate that the locomotor activity rhythm in rats is directly driven by the pacemaker outside the SCN, in which rPer1, rPer2 and rBMAL1 in the CPU and parietal cortex are involved.

[Roles of neuropeptide Y in the expression of anticipatory corticosterone peak in rats under restricted daily feeding]

NPYmRNA in the arcuate nucleus (ARC) and the nucleus of the solitary tract (NST) was measured by quantitative RT-PCR and in situ hybridization in rats under 48-hour food deprivation (FD) or under restricted daily feeding (RF) in which free access to food was restricted to 2 hours per day for 3 weeks. Plasma corticosterone levels were elevated immediately prior to daily food supply under RF, while they remained essentially unchanged by 48-hour FD. On the other hand, the NPYmRNA levels in the ARC were increased by 48-hour FD and RF, while those in the NST were elevated by RF but not by 48-hour FD. These findings indicate that the NPY neurons in the NST are specifically involved in the prefeeding corticosterone peak in the rats the under RF, while the NPY neurons in the ARC are involved in the feeding activity in general and stimulated by decreased food availability.

Antinociception in rat by sarpogrelate, a selective 5-HT(2A) receptor antagonist, is peripheral

The antinociceptive effect of sarpogrelate, a new selective 5-hydroxytriptamine (5-HT)(2A) receptor antagonist, in the formalin test was examined in rats. Sarpogrelate was administered intraperitoneally, locally (subcutaneously at the formalin test site) or intrathecally 10 min before formalin injection. Intraperitoneal (1-100 mg/kg) and local (0.01-1 mg) administration of sarpogrelate suppressed flinching behavior in both phases 1 (0-9 min) and 2 (10-60 min) in a dose-dependent manner. Intraperitoneal (100 mg/kg) and local (1 mg) injection 7 min after formalin injection reduced phase 2 flinches to the same degree as with the pre-treatment. Intrathecal administration (1-100 microg) showed no antinociceptive action, and facilitated phase 2 flinches at 10 microg. The plasma concentration of sarpogrelate after local administration of 1 mg was lower than after intraperitoneal administration of 10 mg/kg, although local administration produced more potent antinociception. The data imply that the antinociceptive effect of sarpogrelate results mainly from an action at peripheral sites.

Cosinor analysis of heart rate variability in ambulatory migraineurs

OBJECTIVE

To clarify whether the circadian rhythm of heart rate variability parameters can be identified in patients with migraine during a headache-free period and to identify any specific pattern of the circadian rhythm of heart rate variability, using time-domain and spectral analysis and cosinor rhythm analysis of heart rate variability during normal daily activity.

METHODS

Forty-eight-hour Holter electrocardiograms were recorded for 27 patients with migraine during headache-free periods and 24 healthy controls during free activity. The circadian rhythms of heart rate fluctuation parameters, that is, mean interval, standard deviation, root-mean-square successive differences (RMSSD), %RR50, and low (0. 020 to 0.150 Hz) and high frequency (0.150 to 0.400 Hz) heart rate fluctuations were analyzed with the group mean cosinor method.

RESULTS

The group mean cosinor analysis and the acrophase-amplitude analysis demonstrated significant differences in circadian rhythm in SD, RMSSD, %RR50, and high frequency between the group with migraine and controls. The amplitudes of SD, RMSSD, %RR50, and high frequency in the group with migraine were smaller than those in controls, which implied parasympathetic hypofunction in migraineurs. There were no significant differences in the MESOR (midline estimating statistic of rhythms) of the analyzed heart rate parameters except for low frequency. The MESOR of low frequency in the migraineurs was significantly smaller than that in the controls.

CONCLUSIONS

Patients with migraine have hypofunction in the parasympathetic nervous system during normal daily activity in the headache-free period.

Polymorphic variation of the ARP gene on 3p21 in Japanese esophageal cancer patients

Allelic loss of the short arm of chromosome 3 is common in esophageal squamous cell carcinoma (ESC) and its premalignant lesions. The ARP gene (Arginine Rich Protein) was mapped to 3p21, and frequent variations of the triplet, AGG, repeat around codon 50 of the ARP gene were reported in a variety of human cancers. To examine the involvement of the ARP gene in esophageal cancer, we screened mutations around codon 50 in 35 ESC tumours and matched normal tissues. Sequence variants were observed in four ESC tumours; two (AGG)2 insertions, one ATG50-to-AGG substitution and one AGG deletion. However, they were also found in its corresponding normal tissues, suggesting that variation of the ARP gene found in ESC is polymorphic. We next analyzed sequence changes in 48 unrelated Japanese healthy individuals. They consist of 33 wild-type homozygotes, nine (AGG)2 insertion/wild-type heterozygotes, two (AGG)2 insertion homozygotes, one AGG deletion/wild-type heterozygote and three ATG50-to-AGG substitution/wild-type heterozygotes. Allele frequencies for wild-type, (AGG)2 insertion, ATG50-to-AGG substitution and AGG deletion are 0.82, 0.14, 0.03 and 0.01, respectively. Observed genotype frequencies fit well with the Hardy-Weinberg's law. Significant difference was not observed between allele distributions in normal and cancer patient populations.

Fine mapping of smallest common regions of deletion on chromosome 12 in liver epithelial and hepatocellular carcinoma cell lines from B6C3F(1) and C3B6F(1) mice

Loss of chromosomes frequently accompanies the establishment of hepatic cell lines in mice. Previous cytogenetic and allelotype studies have revealed that loss of chromosomes 4 and 12 is particularly common. In the present study, fine-deletion mapping was performed for chromosome 12 using 44 liver epithelial (LE) and hepatocellular carcinoma (HCC) cell lines derived from a hybrid between C3H/HeJ (C3H) and C57BL/6J (B6) mice with a high density of polymorphic microsatellite markers. Examination using 15 markers demonstrated that, although 19 of 44 cell lines showed deletion of the whole or large segments of chromosome 12, 3 had very small-range loss. Analysis of the latter using additional markers detected the 2 smallest common regions of deletion (Scrd1 and -2) in the centromeric and telomeric portions. Scrd1 is syntenic to human chromosome 2p and Scrd2 to human chromosome 14q, a region frequently deleted in various types of tumor. Of the 22 cases with loss of heterozygosity, 19 showed loss of B6 alleles. Our results demonstrate that mouse chromosome 12 contains at least 2 independent suppressor loci and that loss of B6 genes may be more advantageous than C3H gene deletion for establishment of hepatic cell lines.

Mitochondrial genome-encoded ATPase subunit 6+8 mRNA increases in human hepatoblastoma cells in response to nonfatal cold stress

Cellular responses to cold stress have not been well clarified, compared with heat shock responses, especially in mammalian cells. We investigated cold-stress responses in human hepatoblastoma cells (HepG2) exposed to a nonfatal temperature of 17 degrees C. Under the condition, RNA and protein syntheses in the cells were highly, but incompletely, depressed and cell growth was impaired. A cDNA subtraction method was used to isolate mRNAs for which the levels were increased in cold-stressed cells compared with cells cultured at 37 degrees C. A transcript isolated by the screening was identified as ATPase subunit 6+8 mRNA that encodes components of a mitochondrial ATPase complex and that is transcribed from a mitochondrial genome. The copy number of the mitochondrial genome in cells was not changed by cold stress. Thus, HepG2 cells were treated with various concentrations of actinomycin D and chloramphenicol to assess the effects of transcriptional and translational reduction on the increased level of the ATPase subunit 6+8 mRNA. The mRNA level was increased in cells treated with low concentrations of the RNA or protein synthesis inhibitors. These results indicate that the increase in ATPase subunit 6+8 mRNA stimulated by cold stress could be mediated by a partial decline of transcription and/or translation in the cells. In addition, the degradation of ATPase subunit 6+8 mRNA was suppressed in cold-stressed cells compared with that in 37 degrees C-cultured cells. This result implies that posttranscriptional regulation is also involved in the cold-stimulated increase in ATPase subunit 6+8 mRNA in HepG2 cells.

Mutation spectrum of MSH3-deficient HHUA/chr.2 cells reflects in vivo activity of the MSH3 gene product in mismatch repair

The endometrial tumor cell line HHUA carries mutations in two mismatch repair (MMR) genes MSH3 and MSH6. We have established an MSH3-deficient HHUA/chr.2 cell line by introducing human chromosome 2, which carries wild-type MSH6 and MSH2 genes, to HHUA cells. Introduction of chromosome 2 to HHUA cells partially restored G:G MMR activity to the cell extract and reduced the frequency of mutation at the hypoxanthine-guanine phosphoribosyltransferase (hprt*) locus to about 3% that of the parental HHUA cells, which is five-fold the frequency in MMR-proficient cells, indicating that the residual mutator activity in HHUA/chr.2 is due to an MSH3-deficiency in these cells. The spectrum of mutations occurring at the HPRT locus of HHUA/chr.2 was determined with 71 spontaneous 6TG(r) clones. Base substitutions and +/-1 bp frameshifts were the major mutational events constituting, respectively, 54% and 42% of the total mutations, and more than 70% of them occurred at A:T sites. A possible explanation for the apparent bias of mutations to A:T sites in HHUA/chr.2 is haploinsufficiency of the MSH6 gene on the transferred chromosome 2. Comparison of the mutation spectra of HHUA/chr.2 with that of the MSH6-deficient HCT-15 cell line [S. Ohzeki, A. Tachibana, K. Tatsumi, T. Kato, Carcinogenesis 18 (1997) 1127-1133.] suggests that in vivo the MutSalpha (MSH2:MSH6) efficiently repairs both mismatch and unpaired extrahelical bases, whereas MutSbeta (MSH2:MSH3) efficiently repairs extrahelical bases and repairs mismatch bases to a limited extent.

Epidural block with mepivacaine before surgery reduces long-term post-thoracotomy pain

PURPOSE

To examine the effect of continuous epidural block initiated before thoracic surgery upon early and long-term postoperative pain.

METHODS

In a double-blind study, 70 patients scheduled for thoracic surgery under general anesthesia were assigned randomly to receive continuous epidural block with mepivacaine 1.5% initiated either 20 min before surgical incision (Pre group) or at completion of surgery (Post group). In both groups the initial dose was 4 ml, followed by a continuous infusion at 4 ml x hr(-1) until 72 hr after operation. Indomethacin suppositories, 50 mg, were administered on request as supplementary analgesics. Visual analogue scale at rest was assessed four hours after operation, and then every 24 hr after operation on postoperative days 1 through 7, and also days 14 and 30. At three and six months after operation, all patients were interviewed by telephone with respect to postoperative pain. The most severe pain was assessed using modified numerical rating scale.

RESULTS

By a visual analogue scale, postoperative pain was less in the Pre group than in the Post group at four hours, two and three days after operation (P < 0.05). By a numerical rating scale six months after operation, pain was less in the Pre group than in the Post group (P = 0.015). The percentage of pain-free patients was higher in the Pre group than in the Post group at three (P = 0.035) and six (P = 0.0086) months after operation.

CONCLUSION

Continuous epidural block initiated prior to surgery may reduce long-term post-thoracotomy pain.