Molecular survey of Bartonella henselae and Bartonella clarridgeiae in pet cats across Japan by species-specific nested-PCR.

Cats are known to be the main reservoir for Bartonella henselae and Bartonella clarridgeiae, which are the agents of 'cat-scratch disease' in humans. In the present study, we investigated the prevalence of the two Bartonella species on 1754 cat bloods collected from all prefectures in Japan during 2007-2008 by a nested-polymerase chain reaction (PCR) targeting the 16S-23S rRNA internal transcribed spacer region. Overall, Bartonella DNA was detected in 4·6% (80/1754) of the cats examined. The nested-PCR showed that 48·8% (39/80) of the positive cats were infected with B. henselae mono-infection, 33·8% (27/80) with B. clarridgeiae mono-infection and 17·5% (14/80) were infected with both species. The prevalence (5·9%; 65/1103) of Bartonella infection in the western part of Japan was significantly higher than that (2·3%; 15/651) of eastern Japan (P < 0·001). Statistical analysis of the cats examined suggested a significant association between Bartonella infection and FeLV infection (OR = 1·9; 95% CI = 1·1-3·4), but not with FIV infection (OR = 1·6; 95% CI = 1·0-2·6).

Ultrasound-guided intralesional laser treatment of venous malformation in the oral cavity.

An ultrasound-guided intralesional photocoagulation (ILP) technique using a laser is described for treatment of deep venous malformations in the oral cavity. ILP is basically a blind operation and has a risk of unintended destruction of surrounding normal tissue, therefore the authors now routinely use guidance by ultrasonography using a mini-probe to improve the safety and reliability of ILP. This approach enables safe fibre insertion, appropriate laser irradiation, and intraoperative assessment of coagulation. The use of this technique is described in 8 patients. The authors conclude that ultrasound-guided ILP with a laser is a promising technique for less-invasive treatment of a vascular malformation in the oral cavity.

A case of maxillary duplication with a soft palate reconstruction using a forearm flap.

Maxillary duplication is a rare congenital anomaly that occurs in the jaw/mouth area. It is generally regarded as sporadic in nature. Total or subtotal soft palate reconstruction for oropharyngeal defects, which include post-surgical and congenital defects, presents a difficult surgical challenge. A maxillary duplication in which the soft palate is reconstructed using a vascularized forearm flap is described. The velopharyngeal insufficiency in the present case is caused by the almost complete deficiency of the soft palate, suggesting that a conventional pharyngeal flap operation with localized mucosal myocutaneous flaps would not produce favorable results in terms of postoperative contractions in the pharyngeal flaps. In such cases, the reconstruction of the soft palate using vascularized free forearm flaps, guided by flexibility regarding the size and adequate thickness of the flaps, may be useful.

Regulation of cell motility via high and low affinity autocrine motility factor (AMF) receptor in human oral squamous carcinoma cells.

A tumour-secreted cytokine autocrine motility factor (AMF) induces in vivo invasion and metastasis, and in vitro tumour cell motility by a signal transduction through interaction with its cell surface receptor gp78. In this report, we investigated the characterization of a high-metastatic human oral squamous cell carcinoma (SCC) cell line LMF4 and low-metastatic HSC-3 in comparison with non-metastatic HSC-2 and HSC-4. Morphological and motility analyses revealed LMF4 cells to have the highest motile activity among those cells. However, LMF4 cells shared the similar features with HSC-3: high level secretion of AMF, enhancement of gp78 expression, co-expression of vimentin and cytokeratin, although LMF4 cells showed twice as high motile reactivity as HSC-3. The only difference was that LMF4 had twice as high amount of low-affinity receptor(s) as HSC-3, shown by Scatchard analysis.

Volatilization of mercury under acidic conditions from mercury-polluted soil by a mercury-resistant Acidithiobacillus ferrooxidans SUG 2-2.

Volatilization of mercury under acidic conditions from soil polluted with mercuric chloride (1.5 mg Hg/kg soil) was studied with resting cells of a mercury-resistant strain, Acidithiobacillus ferrooxidans SUG 2-2. When resting cells of SUG 2-2 (0.01 mg of protein) were incubated for 10 d at 30 degrees C in 20 ml of 1.6 mM sulfuric acid (pH 2.5) with ferrous sulfate (3%) and mercury-polluted soil (1 g), which contained 7.5 nmol of Hg, approximately 4.1 nmol of mercury was volatilized, indicating that 54% of the total mercury in the soil was volatilized. The amount of mercury volatilized from the soil was dependent on the concentration of Fe2+ added to the medium. When elemental sulfur, sodium tetrathionate, and pyrite were used as an electron donor for the mercury reduction, 16, 2.4 and 0.84%, respectively, of the total mercury added to the solution were volatilized. The optimum pH and temperature for mercury volatilization were 2.5 and 30 degrees C. Approximately 92% of the total mercury in a salt solution (pH 2.5) with resting cells of SUG 2-2 (0.01 mg of protein), ferrous sulfate (3%) and mercury-polluted soil (1 g) was volatilized by further addition of both resting cells and Fe2+ and by incubating for 30 d at 30 degrees C.

Free-electron laser etching of dental enamel.

OBJECTIVE: The purpose of this study was to evaluate the Mark-III free-electron laser as a means of etching enamel surfaces, with potential application to resin bonding. METHODS: The FEL was tuned to wavelengths ranging from 3.0 to 9.2 microm. Specific wavelengths that are resonantly absorbed by phosphates, proteins, and water were used. First, bovine enamel was polished and exposed to static FEL exposures. Lased enamel was examined using scanning electron microscopy (SEM). Additional bovine enamel specimens were exposed to FEL at similar wavelengths, but with rastering to create treated rectangular areas on each specimen. Surface roughness was evaluated using profilometry and atomic force microscopy (AFM). Composite was bonded to the lased enamel, and shear bond strengths were determined using an Instron universal testing machine. As a control, the surface roughness of, and shear bond strengths to, acid-etched enamel were determined. RESULTS: Static FEL exposures caused changes in the enamel ranging from an etched appearance to pits, cracks, and frank cratering. The surface roughness of lased enamel was much greater than that of acid-etched enamel, and was qualitatively different as well. Shear bond strengths of resin to acid-etched enamel were significantly higher than bond strengths to lased enamel. CONCLUSIONS: Under the conditions used in this study, the FEL did not offer a practical and effective method of etching enamel for resin bonding. However, the ability of the FEL to deliver many specific wavelengths makes it an interesting tool for further research of laser effects on tooth structure.

Homozygous deletions on the short arm of chromosome 3 in human oral squamous cell carcinomas.

Recent cytogenetic and allelic deletion analyses have demonstrated that deletions on the short arm of chromosome 3 (3p) are frequently found in various cancers, including oral squamous cell carcinomas (OSCCs). This suggests that one or more tumor suppressor gene(s) for these malignancies might be located on 3p. In the present study, to further define the region(s) on 3p that harbor putative tumor suppressor gene(s) for OSCCs, we have investigated the existence of homozygous deletions (HDs) at 34 loci on 3p, in 14 OSCC cell lines. HDs were detected within the FRA3B region at 3p14.2 in only two cell lines (HSC-4 and TSU). Recently, the human fragile histidine triad (FHIT) gene was isolated from this region, abnormalities of which have been found at high frequencies in several types of human cancers. We also examined the expression of the FHIT gene, using reverse transcription-polymerase chain reaction (RT-PCR) and exon-specific PCR, in the two OSCC cell lines which showed HDs at 3p14.2. There was no detectable expression of exon 5, which was the first protein-coding exon of FHIT gene, in HSC-4 cells, indicating that this region was homozygously deleted in this cell line. On the other hand, HD in the TSU cells did not affect the coding region of the FHIT gene, and the wild-type transcript was detected by RT-PCR. Therefore, several candidate tumor suppressor genes, including the FHIT gene, may reside in these homozygously deleted regions. To our knowledge, this is the first report of HDs on 3p in OSCCs.

Mechanism of growth inhibition by tungsten in Acidithiobacillus ferrooxidans.

Cell growth of three hundred iron-oxidizing bacteria isolated from natural environments was inhibited strongly by 0.05 mM, and completely by 0.2 mM of sodium tungstate (Na2WO4), respectively. Since no great difference in the level of tungsten inhibition was observed among the 300 strains tested, the mechanism of inhibition by Na2WO4 was studied with Acidithiobacillus ferrooxidans strain AP19-3. When resting cells of AP19-3 were incubated in 0.1 M beta-alanine-SO4(2-) buffer (pH 3.0) with 0.1 mM Na2WO4 for 1 h, the amount of tungsten bound to the cells was 12 microg/mg protein. The optimum pH for tungsten binding to the resting cells was 2 to approximately 3. Approximately 2 times more tungsten bound to the cells at pH 3.0 than at pH 6.0. The tungsten binding was specifically inhibited by sodium molybdenum. However, copper, nickel, cadmium, zinc, manganese, cobalt, and vanadate did not disturb tungsten binding to the resting cells. The iron-oxidizing activity of AP19-3 was inhibited 24, 62, and 77% by 1, 5, and 10 mM of Na2WO4, respectively. Among the components of iron oxidation enzyme system, iron:cytochrome c oxidoreductase activity was not inhibited by 10 mM of Na2WO4. In contrast, the activity of cytochrome c oxidase purified highly from the strain was inhibited 50 and 72%, respectively, by 0.05 and 0.1 mM of Na2WO4. The amounts of tungsten bound to plasma membrane, cytosol fraction, and a purified cytochrome c oxidase were 8, 0.5, and 191 microg/mg protein, respectively. From the results, the growth inhibition by Na2WO4 observed in A. ferrooxidans is explained as follows: tungsten binds to cytochrome c oxidase in plasma membranes and inhibits cytochrome c oxidase activity, and as a results, the generation of energy needed for cell growth from the oxidation of Fe2+ is stopped.

Cytochrome c oxidase purified from a mercury-resistant strain of Acidithiobacillus ferrooxidans volatilizes mercury.

We suggested in our previous study that the plasma membrane cytochrome c oxidase of the mercury-resistant iron-oxidizing bacterial strain Acidithiobacillus ferrooxidans, SUG 202, is involved in Fe2+-dependent mercury volatilization. To study the involvement of A. ferrooxidans cytochrome c oxidase in mercury reduction, the cytochrome c oxidase was extracted from mercury-resistant and mercury-sensitive strains and purified. The Fe2+-dependent mercury volatilization activities of the oxidases from these strains were compared. The cytochrome c oxidase from strain SUG 2-2 volatilized 39% of the total Hg2+ (7 nmol) that had been added to a 10-ml reaction mixture (pH 3.8) in the presence of 10 micromol of Fe2+ after a 7-d incubation period at 30 degrees C. In contrast, the enzyme purified from the mercury-sensitive strain AP19-3 volatilized 3.5% of the total mercury under the same conditions. The boiled SUG 2-2 oxidase did not exhibit activity to volatilize mercury. Fe2+ reduced the oxidase from SUG 2-2 and Hg2+ oxidized the reduced enzyme. The purified SUG 2-2 oxidase is composed of three protein subunits with apparent molecular weights of 56,000 Da (alpha), 24,000 Da (beta), and 19,000 Da (gamma). The amount of mercury bound to the purified SUG 2-2 oxidase was 6.2 microg/mg protein and those bound to alpha-, beta- and gamma-subunits of the cytochrome c oxidase were 3.5, 2.6 and 0.7 microg/mg protein, respectively.

The role of whole-body FDG-PET in preoperative assessment of tumor staging in oral cancers.

OBJECTIVE: The aim of this study is to clarify the clinical utility of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET) in determining the TNM classification in patients with oral cancer. METHODS: Twenty-five consecutive patients (14 male and 11 female; age range, 40 yr to 86 yr) with oral cancer were included in this study. The diagnostic accuracy for detecting cervical lymph nodes was investigated by comparing the results of CT and/or MRI and physical findings. For the semi-quantitative analysis, the tumor standardized uptake value (SUV) and tumor to background SUV ratio (T/B ratio) were assessed in primary tumors and cervical lymph nodes. RESULTS: All primary lesions were visualized on FDG-PET images. Even though artifacts from dental materials near the lesion hampered the delineation of primary tumors on CT/MRI, the extent of primary tumors was accurately assessed by FDG-PET. The SUV and T/B ratio in the primary tumor classified in higher T grade (T3 and T4) was significantly higher than that in lower T grade (T1 and T2) (mean +/- SD of SUV; 8.32 +/- 2.99 vs. 5.15 +/- 3.77, p < 0.01, mean +/- SD of T/B ratio; 6.96 +/- 3.23 vs. 3.61 +/- 2.76, p < 0.01). The SUV and T/B ratio of metastatic lymph nodes were also significantly higher than those of normal lymph nodes (mean +/- SD of SUV; 3.39 +/- 1.69 vs. 1.55 +/- 0.57, p < 0.001, mean +/- SD of T/B ratio; 2.46 +/- 1.08 vs. 1.03 +/- 0.22, p < 0.001). Among these three methods, FDG-PET in conjunction with CT/MRI showed the highest accuracy of 92%, but there were no significant differences in diagnostic accuracy among the three methods. For the semi-quantitative analysis, a threshold SUV of 2.0 provided 100% sensitivity, 82% specificity, and 88% accuracy. Furthermore, a threshold T/B ratio of 1.5 provided 100% sensitivity, 100% specificity, and 100% accuracy. Regarding the detection of distant metastasis, there was one positive result in FDG-PET showing distant pulmonary metastasis. CONCLUSIONS: Whole-body FDG-PET is an effective and convenient diagnostic tool for the evaluation of tumor staging in patients with oral cancer. Tumor staging by whole-body FDG-PET may, in fact, supplement the conventional staging by means of CT/MRI and physical findings.

Study of the cause of the temperature rise at the muscle-bone interface during ultrasound hyperthermia.

Undesirable temperature rise at the muscle-bone interface has been one of the major problems during ultrasound hyperthermia treatment. In this study, we examined by both computer calculation and phantom experiment the cause of this problem. Ultrasound penetrates a bone in two different waveforms, longitudinal and transversal. The transmission coefficient of these two waves vary greatly with the incident angle. From both theoretical and experimental results, the incident angle dependency of the interface heat was confirmed. When the incident angle is less than the critical angle of the longitudinal wave, the main cause of the temperature elevation is the absorption of the longitudinal wave in the bone. When the incident angle is larger than the critical angle of the longitudinal wave, the transversal wave becomes the major cause of the heat generation. At the incident angles larger than the critical angle of the transversal wave, no temperature rise is produced by the absorption of the ultrasound at the bone; the incident longitudinal wave, strengthened by the reflected wave, is absorbed in the muscle just in front of the bone. The heat generated in the muscle is transported to the interface so that the temperature of the interface and bone increases slightly.

Overexpression of nm23-H2/NDP kinase B in a human oral squamous cell carcinoma cell line results in reduced metastasis, differentiated phenotype in the metastatic site, and growth factor-independent proliferative activity in culture.

The metastasis suppressor activity of nm23/nucleoside diphosphate (NDP) kinase was assessed using human oral squamous cell carcinoma (SCC) cell lines. When the expression of nm23/NDP kinase was compared among several SCC cell lines, nm23-H2/NDP kinase B gene product, but not nm23-HI/NDP kinase A gene product, was reduced in the metastatic cells. Transfection of nm23-H2 into the metastatic SCC cell line LMF4 caused reduction in the lung metastasis in an experimental metastasis assay. A histological analysis of the pulmonary metastatic foci revealed that although foci of the control clones were composed of anaplastic squamous cells, those of the nm23-H2-transfected clones consisted of mostly well-differentiated cells mimicking normal stratified epithelial constitution. The transfected cells were morphologically indistinguishable from the control ones in culture, but they differed from each other in that the former cells proliferated faster than the latter, became less serum dependent, and lost responsiveness to growth factors such as platelet-derived growth factor, insulin-like growth factor I, and insulin, although both clones retained sensitivity to transferrin. These results demonstrate that nm23-H2 protein does have metastasis suppressor activity for human SCC cells and suggest that this activity may be elicited by modulating growth and/or differentiation potential in response to environmental factors.

Inactivation patterns of the p16 (INK4a) gene in oral squamous cell carcinoma cell lines.

To determine whether inactivation of the p16 gene mapped to the chromosome 9p21 region is associated with the development of oral squamous cell carcinoma (SCC), we investigated the mutational states of two forms of alternative transcripts (alpha and beta) from the p16 gene in 14 oral SCC cell lines by means of RT-PCR, PCR, direct sequencing and methylation analyses. Alterations of the alpha transcript were detected in all of the cell lines examined: homozygous deletions in three lines; subtle mutations in exons 1 alpha or 2 in four lines; skipping of exon 2 in two lines; hypermethylation of the 5' CpG island of the p16 gene in four lines; and an unknown mechanism in one line. On the other hand, abnormalities of the beta transcript were observed in seven of the 14 cell lines. Nonetheless, the mutations that essentially affect the function of the encoded protein were found only in five cell lines, including three lines with homozygous deletion. There was no cell line having only beta transcript alterations. Thus, alteration of the alpha transcript of the p16 gene was a highly frequent event in oral SCC. Since this type of alteration resulted in gene inactivation through multiple pathways, it may play a major role in the process of oral SCC development.

Isolation of iron-oxidizing bacteria from corroded concretes of sewage treatment plants.

Thirty-six strains of iron-oxidizing bacteria were isolated from corroded concrete samples obtained at eight sewage treatment plants in Japan. All of the strains isolated grew autotrophically in ferrous sulfate (3.0%), elemental sulfur (1.0%) and FeS (1.0%) media (pH 1.5). Washed intact cells of the 36 isolates had activities to oxidize both ferrous iron and elemental sulfur. Strain SNA-5, a representative of the isolated strains, was a gram-negative, rod-shaped bacterium (0.5-0.6x0.9-1.5 microm). The mean G+C content of its DNA was 55.9 mol%. The pH and temperature optima for growth were 1.5 and 30 degrees C, and the bacterium had activity to assimilate 14CO2 into the cells when ferrous iron or elemental sulfur was used as a sole source of energy. These results suggest that SNA-5 is Thiobacillus ferrooxidans strain. The pHs and numbers of iron-oxidizing bacteria in corroded concrete samples obtained by boring to depths of 0-1, 1-3, and 3-5 cm below the concrete surface were respectively 1.4, 1.7, and 2.0, and 1.2 x 10(8), 5 x 10(7), and 5 x 10(6) cells/g concrete. The degree of corrosion in the sample obtained nearest to the surface was more severe than in the deeper samples. The findings indicated that the levels of acidification and corrosion of the concrete structure corresponded with the number of iron-oxidizing bacteria in a concrete sample. Sulfuric acid produced by the chemolithoautotrophic sulfur-oxidizing bacterium Thiobacillus thiooxidansis known to induce concrete corrosion. Since not only T. thiooxidans but also T. ferrooxidans can oxidize reduced sulfur compounds and produce sulfuric acid, the results strongly suggest that T. ferrooxidans as well as T. thiooxidans is involved in concrete corrosion.

Isolation of a Sulfur-oxidizing Bacterium That can Grow under Alkaline pH, from Corroded Concrete.

To study the early stages of concrete corrosion by bacteria, sulfur-oxidizing bacterium strain RO-1, which grows in an alkaline thiosulfate medium (pH 10.0) was isolated from corroded concreate and characterized. Strain RO-1 was a Gram negative, rod-shaped bacterium (0.5-0.6×0.9-1.5 µm). The mean G+C content of the DNA of strain RO-1 was 65.0 mol%. Optimum pH and temperature for growth were 8.0. and 30-37°C, respectively. When grown in thiosulfate medium with pH 10.0, growth rate of the strain was 48% of that observed at the optimum pH for growth. Strain RO-1 used sulfide, thiosulfate, and glucose, but not elemental sulfur or tetrathionate, as a sole energy source. Strain RO-1 grew under anaerobic conditions in pepton-NO3 (-) medium containing sodium nitrate as an electron acceptor, and had enzyme activities that oxidized sulfide, elemental sulfur, thiosulfate, sulfite, and glucose, but not tetrathionate. The bacterium had an activity to assimilate (14)CO2 into the cells when thiosulfate was used as an energy source. These results suggest that strain RO-1 is Thiobacillus versutus. Strain RO-1 exuded Ca(2+) from concrete blocks added to thiosulfate medium with pH 9.0 and the pH of the medium decreased from 9.0 to 5.5 after 22 days of cultivation. In contrast, Thiobacillus thiooxidans strain NB1-3 could not exude Ca(2+) in the same thiosulfate medium, suggesting that strain RO-1, but not T. thiooxidans NB1-3, is involved in the early stage of concrete corrosion because concrete structures just after construction contain calcium hydroxide and have a pH of 12-13.

Expression of cyclooxygenase genes and involvement of endogenous prostaglandin during osteogenesis in the rat tibial bone marrow cavity.

Many researchers have demonstrated that the administration of prostaglandins (PGs), especially PGE2, increases the bone volume in vivo. It is still not clear how endogenous PG is associated with such bone formation. Cyclooxygenase (COX), which acts in the synthesis of PG from arachidonic acid, has been recently revealed to have two subtypes, a constitutive type (COX-1) and an inducible one (COX-2). We examined the expression of each COX subtype during osteogenesis with the established model of the rat tibial medullary cavity in which osteogenesis can be induced by the injection of colchicine. The expression of both COX-1 and COX-2 genes was enhanced after colchicine injection in the early stage before the start of bone formation. Only the COX-2 gene expression was elevated again later during the beginning of bone formation. Furthermore, the daily administration of indomethacin, COX inhibitor, could reduce the bone mass induced by colchicine in the rat tibiae. These data indicate that endogenous PGs are associated with osteogenesis in this model. Moreover, the present study suggests that COX-2 and COX-1 would both be involved in the early stage of osteogenesis, and COX-2 is likely to be more associated with the maturation of osteoblasts in the later stage.

Autocrine motility factor and its receptor expressions in human oral squamous cell carcinoma (SCC) cells.

Autocrine motility factor (AMF) a tumor-secreted 55 kDa cytokine induces tumor cell motility by a signal transduction pathway mediated by interaction with its receptor (AMFR) a cell surface glycoprotein of 78 kDa (gp78). Here, AMF secreted by the metastatic LMF4 human oral squamous-cell carcinoma (SCC) cells, induced dose- and time-dependent morphological changes and chemotaxis of the producing cells. Expression of AMFR mRNA was associated with the metastatic ability of SCC cell variants. The data presented show for the first time that SCC cells produce AMF and express AMFR and the expression is related to their invasiveness and metastatic potentials.

[A case of bilateral cerebellar peduncle infarction with bilateral hearing impairment of a sudden onset].

We reported a patient with bilateral cerebellar peduncle infarcts who had an abrupt onset of bilateral hearing loss. A hypertensive 56-year-old man suddenly experienced bilateral hearing loss without other accompanying neurological deficits. He was hospitalized and treated for "idiopathic deafness". In addition, dysarthria and ataxic gait appeared two days later and he was transferred to our hospital. On neurological examination, the patient presented with diplopia, neurosensory hearing loss (approximately 70 dB) ataxic dysarthria, bilateral cerebellar ataxia and bilateral Babinski's signs. Auditory brain stem evoked response demonstrated prolonged delay of interpeak latency between waves III-IV. CT and MRI revealed fresh ischemic lesions symmetrically located at the middle cerebellar peduncles and cerebellar medullary body. Cerebral angiography showed total occlusion of the left vertebral artery and a stenotic right vertebral artery at the ostium of the posterior inferior cerebellar artery. We postulated that hearing impairment in this patient resulted from transient ischemia of the bilateral auditory tract in the brain stem or the peripheral cochlear system, but the definitive cause of the transient hearing loss remains undetermined. Concomitant appearance of a symmetrical infarction at the cerebellar peduncles is rare. We suggest that a circulation defect involving a multivascular system, which resulted in "border zone infarction" occurred at these regions.

Human T lymphotropic virus type I associated myelopathy and myasthenia gravis: a possible association?

We report the first known patient with human T lymphotropic virus type I (HTLV-I) associated myelopathy (HAM) and myasthenia gravis (MG). A 50-year-old woman developed fluctuating muscle weakness with easy fatigability, transient bilateral blepharoptosis and double vision. Spastic paraparesis complicated these symptoms. Neurological assessments and specific laboratory findings revealed that the patient had definite HAM and MG. By inference from decreasing serum anti-HTLV-I antibody titers after thymectomy, the presence of antigenicity for HTLV-I in the thymic reticular cells, and a high incidence of various coexistent autoimmune diseases in HAM or MG, we suggested the possibility that these two diseases were associated with each other and with HTLV-I infection.

Reaction of sevoflurane and its degradation products with soda lime. Toxicity of the byproducts.

Sevoflurane previously has been reported to undergo extensive degradation in the presence of soda lime. To more completely characterize the extent and significnce of this reaction, we studied degradation of sevoflurane with and without soda lime, as well as the toxicity and mutagenicity of the degradation products. Two degradation products detected were CF2 = C(CF3)OCH2F (compound A) and CH3OCF2CH(CF3)OCH2F (compound B). During circulation of 1%, 2%, and 3% sevoflurance in a closed anesthesia circuit for 8 h, peak concentrations of compound A were 13.3 +/- 0.27, 30.2 +/- 0.10, and 42.1 +/- 1.07 ppm at 2 h, respectively. The concentrations of compound B did not exceed 2 ppm. The temperature of the soda lime was 43.3 +/- 2.8 degrees C at 1 h and increased gradually to 47.9 +/- 1.5 degrees C after 8 h. In closed flasks with soda lime, the magnitude of the decrease in sevoflurance concentrations (3%) and of the increase in compound A concentrations was temperature dependent. The peak concentrations of compound A at 23 degrees C, 37 degrees C, and 54 degrees C were 32.8 +/- 6.8 at 2 h, 46.6 +/- 1.0 at 0.5 h, and 78.5 +/- 2.3 ppm at 0.5 h, respectively. The LC50 (50% lethal concentration) of compound A in Wistar rats was 1,090 ppm in males and 1,050 ppm in females exposed for 1 h. The LC50 was 420 ppm in males and 400 ppm in females exposed for 3 h. The chronic toxicity of compound A in Wistar rats was studied by exposing rats 24 times, for 3 h each, to initial concentrations of 30, 60, or 120 ppm in a ventilated chamber. At all concentrations, there were no apparent effects other than a loss of body weight in females (120 ppm) on the final day (P < 0.01). Compound A did not induce mutation on the reverse (Ames) test at less than 2,500 micrograms/dish (culture medium 2.7 ml) with activation by S-9 mixture, and below 1,250 micrograms/dish (culture medium 2.7 ml) without activation, in four strains of S. typhimurium and in 1 strain of E. coli. Exposure of fibroblasts to 7,500 ppm of compound A for 1 h, compound A did not induce structural change. In a study of acute toxicity of compound B, there was no toxicity in Wistar rats after 3 h of exposure at 2,400 ppm. The reverse (Ames) test for compound B was negative at 625-1,250 micrograms/dish.(ABSTRACT TRUNCATED AT 400 WORDS)