The Relationship between Dental Findings and Tongue Pressure: A Survey of 745 Community-Dwelling Adults and Elderly Persons in Japan.

INTRODUCTION: Reduced tongue pressure is one of the causes of dysphagia. The purpose of this study was to investigate the relationship between dental findings and tongue pressure, and whether prosthetic treatment prevents reduced tongue pressure. METHODS: This was a cross-sectional study. Participants were 745 community-dwelling adults and elderly persons in the Goto Islands in Nagasaki, who underwent a health checkup for residents in 2015 and 2016. Data were collected on gender; age; grip strength; hemoglobin; Creatinine (Cr); glycated hemoglobin (HbA1c); history of stroke; smoking, drinking, exercise, and walking habits; number of teeth; wearing of removable dentures; functional units of natural teeth (n-FTUs), fixed prostheses (nif-FTUs), and removable dentures (t-FTUs); and tongue pressure. The associations between each variable and tongue pressure were examined using multiple regression analysis. Next, those with 3 or fewer n-FTUs were selected, and differences in tongue pressure were compared between those with 3 or fewer nif-FTUs and those with 4 or more nif-FTUs, using a propensity score matching method. RESULTS: Male gender, weak grip strength, low HbA1c, no drinking, and a low number of teeth were independent factors significantly associated with lower tongue pressure. Among participants with 3 or fewer n-FTUs, the 43 with 4 or more nif-FTUs showed significantly higher tongue pressure than the 43 with 3 or fewer nif-FTUs after propensity score matching, although the number of t-FTUs was not associated with tongue pressure. DISCUSSION/CONCLUSION: Tooth loss was significantly associated with lower tongue pressure. It was suggested that fixed prosthesis treatment might prevent the reduction of tongue pressure, but removable dentures did not have such an effect.

Association between high psychological distress and poor oral health-related quality of life (OHQoL) in Japanese community-dwelling people: the Nagasaki Islands Study.

BACKGROUND: We investigated the association between psychological distress and oral health status/oral health-related quality of life (OHQoL) in Japanese community-dwelling people. METHODS: We conducted a cross-sectional study using data from the Nagasaki Islands Study. A total of 1183 (455 men and 728 women) has been analyzed in this study. Psychological distress was measured using the Kessler Psychological Distress Scale (K6). Oral health status was measured by dental examination. The OHQoL was measured using the General Oral Health Assessment Index (GOHAI). We defined the total score of ≥5 points on the K6 as high psychological distress (high-K6 group). RESULTS: The multiple linear regression analysis to identify the GOHAI showed that gender, K6, the total number of teeth, the number of dental caries, and visiting a dental clinic within the past 6 months significantly associated with the GOHAI. Among all of these variables, high-K6 (≥ 5) was a substantial contributing factor of the GOHAI (ß = - 0.23, 95% Cl - 2.31 to -1.41, p < 0.0001). CONCLUSIONS: It is likely that the individual with high psychological distress was strongly related to poor OHQoL even in the general population.

Association between number of pairs of opposing posterior teeth, metabolic syndrome, and obesity.

We investigated the relationship between the number of pairs of posterior teeth and metabolic syndrome (MetS), abdominal obesity (AO), and obesity, among Japanese adults. In 2005, 2,807 Japanese adults aged 25-74 years participated in the Survey of Dental Diseases and the National Health and Nutrition Survey. Based on the survey data, BMI, AO (JAS) determined by the Japan Atherosclerosis Society, AO (IDF) by the International Diabetes Federation, and MetS were assessed. Total functional tooth units (t-FTUs) were scored with pairs of opposing posterior teeth, including artificial teeth. Subjects were divided into three categories of chewing ability based on the score of t-FTUs: Poor (if score ≤ 9), Good (if score = 10-11), and Complete (if score = 12). The relationships between chewing ability and BMI ≥ 25, BMI ≥ 30, AO (JAS), AO (IDF), and MetS were tested using univariate and multivariate logistic regression analysis. The chewing ability was significantly associated with MetS, AO, and obesity in the univariate and multivariate logistic regression analysis. Adjusted OR of "Poor" compared to "Complete" were 1.51 (95% confidence interval (CI), 1.24-1.84) for BMI ≥ 25, 2.10 (95% CI 1.40-3.14) for BMI ≥ 30, 1.31 (95% CI 1.07-1.61) for AO (JAS), 1.40 (95% CI 1.15-1.70) for AO (IDF), and 1.34 (95% CI 1.04-1.72) for MetS. All were statistically significant. Preventing tooth loss and maintaining pairs of good chewing ability may be important factors in preventing MetS, AO, and obesity.

Association between human T cell leukemia virus type-1 (HTLV-1) infection and advanced periodontitis in relation to atherosclerosis among elderly Japanese: a cross-sectional study.

BACKGROUND: Human T cell leukemia virus type-1 (HTLV-1) stimulates inflammation activity. Our previous study revealed a positive association between asymptomatic HTLV-1 infection and advanced periodontitis among elderly Japanese individuals with low levels of hematopoietic activity (reflected by reticulocyte levels). Since low hematopoietic activity has been correlated with low-grade inflammation and low-grade inflammation is associated with atherosclerosis, the status of atherosclerosis could, in turn, determine the nature of this association. METHODS: To this end, a cross-sectional study of 907 elderly Japanese individuals (aged 60-99 years), who had participated in dental health check-up during the period 2016-2018, was conducted. Advanced periodontitis was defined as periodontal pocket ≥ 6.0 mm. RESULTS: Among the study population, 295 (32.5%) were found to have atherosclerosis defined as a carotid intima-media thickness (CIMT) of ≥ 1.1 mm. HTLV-1 infection was positively associated with advanced periodontitis in participants with atherosclerosis, but no significant associations were observed among the participants without atherosclerosis. The known risk factors' (including reticulocyte and CIMT) adjusted odds ratio (OR) and 95% confidence interval (CI) of advanced periodontitis were OR 2.01 and 95% CI 1.06-3.81 for participants with atherosclerosis and OR 0.61 and 95% CI 0.34-1.12 for participants without atherosclerosis. CONCLUSION: This study found a significant association between HTLV-1 infection and advanced periodontitis among elderly Japanese with atherosclerosis. However, this association is absent in individuals without atherosclerosis, suggesting that atherosclerosis might act as a determinant in the association between HTLV-1 infection and advanced periodontitis among elderly Japanese.

Association between human T cell leukemia virus 1 (HTLV-1) infection and advanced periodontitis in relation to hematopoietic activity among elderly participants: a cross-sectional study.

BACKGROUND: We reported that human T cell leukemia virus 1 (HTLV-1) infection is positively associated with atherosclerosis. Recent evidence has revealed a close association of periodontitis with atherosclerosis, endothelial dysfunction, and disruption of the microcirculation. However, the association between HTLV-1 and advanced periodontitis has not been investigated to date. Since hematopoietic activity is closely linked to endothelial maintenance activity and is known to decline with age, we hypothesized that the state of hematopoietic activity influenced the association between HTLV-1 and advanced periodontitis in elderly participants. METHODS: A cross-sectional study was performed including 822 elderly participants aged 60-99 years who participated in a dental health check-up. Advanced periodontitis was defined as a periodontal pocket ≥ 6.0 mm. Participants were classified as having low or high hematopoietic activity according to the median values of reticulocytes. RESULTS: HTLV-1 infection was positively related to advanced periodontitis among participants with lower hematopoietic activity (lower reticulocyte count), but not among participants with higher hematopoietic activity (higher reticulocyte count). The adjusted odds ratio (95% confidence interval) considering potential confounding factors was 1.92 (1.05-3.49) for participants with a lower reticulocyte count and 0.69 (0.35-1.36) for participants with a higher reticulocyte count. CONCLUSIONS: Among elderly participants, the association between HTLV-1 infection and advanced periodontitis is influenced by hematopoietic activity. Since hematopoietic activity is associated with endothelial maintenance, these findings provide an efficient tool for clarifying the underlying mechanism of the progression of periodontitis among elderly participants.

Relationship among salivary antioxidant activity, cytokines, and periodontitis: the Nagasaki Island study.

AIM: Antioxidant activities and cytokine levels in human body fluids are considered to be strongly associated with periodontitis. The aim of this study was to elucidate the relationship between salivary antioxidant activities against superoxide or hydroxyl radical, cytokines, and periodontal conditions through a community-based cross-sectional study conducted in Goto city, Japan. MATERIALS AND METHODS: Saliva samples were analysed for superoxide or hydroxyl radical scavenging activities and cytokine levels from 160 participants. We demonstrated that saliva contained superoxide and hydroxyl radical scavenging activities by using electron spin resonance with a spin-trapping agent. The concentrations of eight cytokines were measured using multiplex bead assays. RESULTS: There were significant differences in salivary superoxide or hydroxyl radical scavenging activity, and the levels of Interleukin-1ß, Interleukin-6, and Interleukin-8 between periodontitis classifications. Multivariate stepwise logistic regression model showed that salivary superoxide and hydroxyl radical scavenging activities were significantly associated with the classification of periodontitis. In addition, salivary superoxide scavenging activity was found to have significant association with all periodontal parameters using multiple linear regression analysis. CONCLUSIONS: These findings suggest that the evaluation of salivary antioxidant activities, as assessed by electron spin resonance, are associated with periodontitis and various clinical variables in community-dwelling participants (ClinicalTrials.gov number NCT01742728).

Quantitative discrimination of Aggregatibacter actinomycetemcomitans highly leukotoxic JP2 clone from non-JP2 clones in diagnosis of aggressive periodontitis.

BACKGROUND: Aggregatibacter actinomycetemcomitans is the etiological agent of periodontitis, and there is a strong association between clone JP2 and aggressive periodontitis in adolescents of African descent. The JP2 clone has an approximately 530-bp deletion (∆530) in the promoter region of the lkt/ltx gene, which encodes leukotoxin, and this clone has high leukotoxic activity. Therefore, this clone is very important in aggressive periodontitis. To diagnose this disease, culture methods and conventional PCR techniques are used. However, quantitative detection based on qPCR for the JP2 clone has not been developed due to genetic difficulties. In this study, we developed a qPCR-based quantification method specific to the JP2 clone. METHODS: Based on our analysis of the DNA sequence of the lkt/ltx gene and its flanking region, we designed a reverse primer specific for the ∆530 deletion border sequence and developed a JP2-specific PCR-based quantification method using this primer. We also analyzed the DNA sequence of the ∆530 locus and found it to be highly conserved (97-100%) among 17 non-JP2 strains. Using the ∆530 locus, we designed a qPCR primer-probe set specific to non-JP2 clones. Next, we determined the numbers of JP2 and non-JP2 clone cells in the periodontal pockets of patients with aggressive periodontitis. RESULTS: The JP2-specific primers specifically amplified the genomic DNA of the A. actinomycetemcomitans JP2 clone and did not react with other bacterial DNA, whereas the non-JP2 specific primers reacted only with A. actinomycetemcomitans non-JP2 clones. Samples from the 88 periodontal sites in the 11 patients with aggressive periodontitis were analyzed. The bacterial cell numbers in 88 periodontal sites ranged from 0 to 4.8 × 10(8) (mean 1.28 × 10(7)) for JP2 clones and from 0 to 1.6 × 10(6) for non-JP2 clones (mean 1.84 × 10(5)). There were significant differences in the JP2 cell number between a clinical attachment level (CAL) ≤6 mm and a level ≥7 mm (p < 0.01). Our new qPCR-based JP2- and non-JP2-specific quantitative detection assay is applicable to the diagnosis of aggressive periodontitis with A. actinomycetemcomitans. CONCLUSIONS: We successfully developed a quantitative and discriminative PCR-based method for the detection of A. actinomycetemcomitans JP2 and non-JP2 clones. This technique will contribute to future analyses of the quantitative relationship between this organism and aggressive periodontitis.

Oral health-related quality of life is associated with physical frailty: A cross-sectional study of Japanese community-dwelling older adults.

BACKGROUND: Physical frailty is related to adverse outcomes, and poor oral health has been linked to malnourishment. Subjective measures of oral health-related quality of life (OHRQoL) have been used as indicators of the oral health problems of older adults, and they have been associated with malnourishment. This study aimed to assess OHRQoL's association with physical frailty. METHODS: Cross-sectional study was conducted using data from the Nagasaki Islands Study that enrolled participants aged ≥60 years at Japanese national medical check-ups from 2014 to 2019. Physical frailty phenotype criteria were determined using the modified Fried frailty phenotype model. OHRQoL was assessed using the Geriatric Oral Health Assessment Index (GOHAI). Dentists conducted clinical dental examinations. Simple correlation and linear regression analyses were performed to investigate the associations of number of physical frailty phenotype criteria with GOHAI and other oral health indicators. RESULTS: Among 1341 participants with a mean age of 72 years, GOHAI score was significantly associated with number of physical frailty phenotype criteria (B = -0.01, 95% confidence interval: -0.02 to -0.01, p < 0.001). The association remained significant after adjustment for age, sex, body mass index, history of hypertension, history of diabetes mellitus, smoking status, Kessler-6 score, and number of remaining teeth. CONCLUSIONS: Oral health-related quality of life was associated with physical frailty in Japanese community-dwelling older adults.

Association of low fetuin-A levels with periodontitis in community-dwelling adults.

Fetuin-A is a liver-secreted glycoprotein isolated from fetal bovine serum. Recent reports of its several pathological functions suggest an association between fetuin-A and systemic diseases. This study therefore examined the correlation between serum fetuin-A level and periodontal status. Data from 356 middle-aged and elderly adults who underwent health examinations in Goto, Japan, during the period from 2008 through 2010 were analyzed. Systemic and periodontal measurements were recorded, and serum fetuin-A level was determined by using an enzyme-linked immunosorbent assay. Fetuin-A levels for participants with moderate to severe periodontitis were significantly lower than those for participants with no or mild periodontitis. Additionally, fetuin-A level negatively correlated with periodontal clinical attachment loss. Moderate to severe periodontitis was significantly correlated with low serum fetuin-A levels (odds ratio, 1.69; 95% confidence interval, 1.01-2.69) in logistic regression analysis. Low serum fetuin-A level was correlated with worse periodontal status and could thus potentially serve as a marker of periodontitis.

Dental caries in 3-year-old children is associated more with child-rearing behaviors than mother-related health behaviors.

OBJECTIVE: We assessed whether child- or mother-related health behaviors were associated more strongly with dental caries in 3-year-old children. METHODS: Multiple logistic regression analyses were performed on dental caries' presence as the dependent variable with independent variables from the results of examination and a self-administered questionnaire of 396 mother-child pairs. RESULT: Dental caries of 3-year-old children was more strongly associated with child-related health behavior than mother-related health behavior. Of the child-related variables, "a habit of feeding in bed" [OR (odds ratio) 10.14; 95 percent class interval (CI) 1.80-56.97], "eating between meals three times a day or more" (OR 3.33; 95 percent CI 1.56-7.10), "consuming a sports drink three times a week or more" (OR 4.47; 95 percent CI 1.60-12.49), "having both home and professional preventive dental care" (OR 3.02; 95 percent CI 1.44-6.32), and "having professional preventive dental care" (OR 3.79; 95 percent CI 1.75-8.21) were significantly associated with dental caries in children. Of the mother-related variables, "brushing teeth once a day or less" (OR 2.72; 95 percent CI 1.19-6.20) and "drinking alcohol three times a week or more" (OR 0.38; 95 percent CI 0.16-0.93) had significant effects. CONCLUSION: Dental caries of 3-year-old children was more strongly associated with child-related health behavior than mother-related health behavior. The results of this study suggest that encouraging good child-rearing behavior among mothers could result in better dental health among their children regardless of the mother's dental health status.

Relationship between periodontal status and HbA1c in nondiabetics.

OBJECTIVES: Many studies have reported an association between diabetes and periodontitis. We analyzed the periodontal status and glycosylated hemoglobin (HbA1c) level in nondiabetic subjects to investigate the relationship between periodontitis and glucose control in nondiabetics. METHODS: Periodontal status, HbA1c, serum cholesterol, triglyceride, body mass index (BMI), and demographic variables were assessed in 141 Japanese adults. The difference in the HbA1c level was evaluated among subjects according to periodontal status. RESULTS: After adjusting for age, gender, BMI, and smoking, alcohol, and exercise habits as covariates, the mean HbA1c was significantly elevated with periodontal deterioration (P = 0.023). CONCLUSIONS: There was a significant relationship between periodontal status and HbA1c levels in nondiabetics.

Associations among Obesity, Eating Speed, and Oral Health.

OBJECTIVE: This study was conducted to understand how eating speed and oral health condition are associated with obesity in Japanese working men. METHODS: We studied a total of 863 men attending an annual medical checkup of the Japanese Maritime Self Defense Force in Sasebo City, Japan. Participants answered a questionnaire about their eating speed, and we examined their anthropometric status in terms of BMI, waist circumference, and oral health condition, especially periodontal disease and number of functional teeth. Multivariate logistic regression analyses adjusting for potential confounding variables were performed. RESULTS: The multivariate-adjusted odds ratio for waist circumference greater than 90 cm of the 'very fast' group compared to the 'slow, very slow' group was 5.22 (95% confidence interval 1.81-15.06) after adjusting for potential confounding factors. Individuals were more likely to have waist circumference greater than 90 cm if they had a larger 'number of missing functional teeth' (odds ratio 1.14; 95% confidence interval 1.01-1.28) and severe periodontal disease (odds ratio 2.74; 95% confidence interval, 1.46-5.13). CONCLUSION: Eating speed, the number of missing functional teeth, and severe periodontal disease are associated independently with larger waist circumference.

Enamel fluoride uptake from mouthrinse solutions with different NaF concentrations.

OBJECTIVES: The influence on enamel fluoride uptake of reducing the NaF concentration of a mouthrinse solution by half, from 0.05-0.025%, was examined in elementary school children. METHODS: The participatory elementary school had employed school-based fluoride mouthrinse with 0.05% NaF solution since 1983, and in 1993, the NaF content was lowered to 0.025%. Dental examination and enamel biopsy of maxillary central incisors were performed just before the NaF content reduction for children who had received the daily 0.05% NaF mouthrinse for 2-5 years since 6 years of age. During 1993-95, dental examination and enamel biopsy were undertaken for newly enrolled 6-year-old children, and the same subjects were re-examined after 2 years. The same series of examinations were conducted for the control group, which consisted of children belonging to another elementary school without a fluoride program. RESULTS: The enamel fluoride concentration of 8-year-old children who used the 0.025% NaF mouthrinse for 2 years was 1810 +/- 535 ppm, reaching the same order as that in children who continued using the 0.05% NaF mouthrinse (1863 +/- 1358 ppm), and was significantly higher than that of children without fluoride programs (1113 +/- 303 ppm). There was no considerable increase of mean DMFT values due to the NaF content reduction. CONCLUSIONS: It was concluded that a daily 0.025% NaF mouthrinse provides the similar fluoride content for enamel as 0.05% NaF mouthrinse as long as the rinsing frequency is maintained.

Association of periodontitis with carotid artery intima-media thickness and arterial stiffness in community-dwelling people in Japan: the Nagasaki Islands study.

OBJECTIVE: Recent studies have suggested an association between periodontitis and atherosclerosis; however, the relationship between periodontal status and arterial alterations should be clarified. The purpose of this study was to examine associations between periodontal status and carotid intima-media thickness (cIMT) and arterial stiffness using the cardio-ankle vascular index (CAVI) in community dwellers. METHODS: A community-based cross-sectional study of 1053 subjects ≥40 years with 10 teeth or more was conducted in Goto, Japan from 2008 to 2010. RESULTS: In a multiple linear regression analysis adjusted for age, sex, number of present teeth, and other confounders, each 1-mm increase in mean periodontal pocket depth corresponded to a 0.02-mm increase in maximal cIMT (ß = 0.018; P = 0.049) and also to a 0.1 increase in mean CAVI (ß = 0.133; P = 0.040). In addition, each 1-mm increase in the mean periodontal attachment loss corresponded to a 0.01-mm increase in maximal cIMT (ß = 0.013; P = 0.040). A multiple logistic regression analysis revealed that each 1-mm increase in mean periodontal pocket depth was associated with an increased risk of a maximal cIMT >1 mm (adjusted odds ratio [OR], 1.430; 95% confidence interval [CI], 1.067-1.918; P = 0.017) and mean CAVI of ≥8 (OR, 1.323; 95% CI, 1.003-1.743; P = 0.047). Furthermore, each 1-mm increase in mean periodontal attachment loss was associated with an increased risk of a maximal cIMT >1 mm (OR, 1.251; 95% CI, 1.032-1.516; P = 0.022). CONCLUSION: A linear, dose-dependent relationship was found between periodontal pocket depth, cIMT, and arterial stiffness.

Cessation age of breast-feeding and pacifier use is associated with persistent finger-sucking.

PURPOSE: Although some studies have reported that breast-feeding and pacifier use influence finger-sucking, few have demonstrated whether the age at cessation of breast-feeding or pacifier use and persistent finger-sucking are related. Therefore, the purpose of this study was to examine whether the age at cessation of breast-feeding and pacifier use influenced persistent finger-sucking. METHODS: A cross-sectional study of 555 36- to 47-month-olds was conducted in Nagasaki, Japan, using a questionnaire. Using the optimal cutoff point in a receiver-operating characteristic curve, the age was estimated at which cessation of pacifier use and breast-feeding had the most significant effect on persistent finger-sucking, and the estimated ages were assessed by multiple logistic regression analysis, incorporating all the questions in the questionnaire as independent variables. RESULTS: The odds ratios for persistent finger-sucking when breast-feeding was stopped at an age younger than 12 months old or when pacifier use was stopped at an age younger than 14 months old were 3.77 (95 percent confidence interval (CI)=1.97-7.22) and 8.62 (95 percent CI=2.56-29.04), respectively. CONCLUSIONS: Cessation of breast-feeding before 12 months old or pacifier use before 14 months old was associated with persistent finger-sucking.

Neutrophil-derived resistin release induced by Aggregatibacter actinomycetemcomitans.

Resistin is an adipokine that induces insulin resistance in mice. In humans, resistin is not produced in adipocytes, but in various leukocytes instead, and it acts as a proinflammatory molecule. The present investigation demonstrated high levels of resistin in culture supernatants of neutrophils that are stimulated by a highly leukotoxic strain of Aggregatibacter actinomycetemcomitans. In contrast, the level of resistin was remarkably low when neutrophils were exposed to two other strains that produce minimal levels of leukotoxin and a further isogenic mutant strain incapable of producing leukotoxin. Pretreatment of neutrophils with a monoclonal antibody to CD18, ß chain of lymphocyte function-associated molecule 1 (LFA-1), or an Src family tyrosine kinase inhibitor before incubation with the highly leukotoxic strain inhibited the release of resistin. These results show that A. actinomycetemcomitans-expressed leukotoxin induces extracellular release of human neutrophil-derived resistin by interacting with LFA-1 on the surface of neutrophils and, consequently, activating Src family tyrosine kinases.

Differences in iron acquisition from human haemoglobin among strains of Actinobacillus actinomycetemcomitans.

To get a better insight into the physiology of the high-toxic JP2 clone of Actinobacillus actinomycetemcomitans serotype b, which is strongly associated with juvenile periodontitis in adolescents of African descent, the modes of iron acquisition in this clone were examined and compared to those of other strains of the species. None of the strains examined could utilize human transferrin as a source of iron. This was in accordance with the presence of a non-functional tbpA gene, which normally encodes the A subunit of the transferrin-binding-protein complex. Southern blot analysis indicated that functional duplications of tbpA were not present in the genome. Thus, A. actinomycetemcomitans seems to be in a process of evolution, in which iron acquisition from host transferrin is not essential as in many other members of the pasteurellaceae. All strains could utilize haem as a source of iron. All 11 A. actinomycetemcomitans strains examined harboured a single genomic sequence with homology to the hgpA gene encoding haemoglobin-binding protein A in Haemophilus influenzae. However, in all three strains belonging to the JP2 clone and in one serotype e strain hgpA was a pseudogene. Seven other strains possessed a functional hgpA gene which, according to insertion mutagenesis experiments, was responsible for the ability of these strains to utilize haemoglobin as a source of iron. Thus, the presence of an hgpA pseudogene and the inability to use human haemoglobin as an iron source discriminate the high-toxic JP2 clone from low-toxic serotype b strains and most other strains of A. actinomycetemcomitans.

Phylogenetic associations of ISAa1 and IS150-like insertion sequences in Actinobacillus actinomycetemcomitans.

The distribution and number of two insertion sequences (ISs), ISAa1 and an IS150-like element, in the genomes of a collection of Actinobacillus actinomycetemcomitans strains previously subjected to population genetic analysis were determined to obtain information about their stability and biological significance. The hybridization patterns revealed that these IS elements are widespread in the genome of A. actinomycetemcomitans strains and that their occurrence agrees with the overall population structure of the species. While the patterns of ISAa1 showed significant evolutionary stability, the IS150-like element showed evidence of intra-genomic variability even within members of the previously identified high-toxicity JP2 clone. Searching of the available genome sequence of strain HK1651 of the JP2 clone (www.genome.ou.edu/act.html) revealed close proximity of the IS elements to housekeeping genes, but no evidence of structural disruption of genes or integrations that may be presumed to influence pathogenic potential.