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A PWM inverter with an induction motor often has a problem with a leakage current that flows through the distributed electrostatic capacitance from the motor windings to the ground. This paper presents an analytical model of the system with leakage current and the strategy to suppress it. Two types of suppression circuits are discussed. The current-type circuit, although compact in size, not only acts as an excellent suppressor but also becomes a high-performance filter of the output voltage.

Abstract Background Matrix metalloproteinase (MMP) is known to be involved in the initial and progressive stages of cancer development, and in the aggressive phenotypes of cancer. This study examines the association of single nucleotide polymorphisms in promoter regions of MMP-1 and MMP-3 with susceptibility to oral squamous cell carcinoma (OSCC). Methods We compared 170 Japanese OSCC cases and 164 healthy controls for genotypes of MMP-1 and MMP-3. Results The frequency of the MMP-1 2G allele was higher and that of the 1G homozygote was lower in the OSCC cases (p = 0.034). A multivariate logistic regression analysis revealed that subjects who were 45 years old or older had a significantly increased (2.47-fold) risk of OSCC (95%CI 1.47–4.14, p = 0.0006), and those carrying the MMP-1 2G allele had a 2.30-fold risk (95%CI 1.15–4.58, p = 0.018), indicating independent involvement of these factors in OSCC. One of the key discoveries of this research is the apparent reduction of the MMP-1 1G/1G and 1G/2G genotype distributions among the early onset OSCC cases under the ages of 45 years. It should be noted that the tongue was the primary site in 86.2% of these early onset cases. This could suggest the specific carcinogenic mechanisms, i.e. specific carcinogenic stimulations and/or genetic factors in the tongue. Conclusion Since the 2G allele is a majority of the MMP-1 genotype in the general population, it seems to act as a genetic pre-condition in OSCC development. However this report suggests a crucial impact of the MMP-1 2G allele in the early onset OSCC.

Background: Matrix metalloproteinase (MMP) is known to be involved in the initial and progressive stages of cancer development, and in the aggressive phenotypes of cancer. This study examines the association of single nucleotide polymorphisms in promoter regions of MMP-1 and MMP-3 with susceptibility to oral squamous cell carcinoma (OSCC). Methods: We compared 170 Japanese OSCC cases and 164 healthy controls for genotypes of MMP-1 and MMP-3. Results: The frequency of the MMP-1 2G allele was higher and that of the 1G homozygote was lower in the OSCC cases (p = 0.034). A multivariate logistic regression analysis revealed that subjects who were 45 years old or older had a significantly increased (2.47-fold) risk of OSCC (95%CI 1.47-4.14, p = 0.0006), and those carrying the MMP-1 2G allele had a 2.30-fold risk (95%CI 1.15-4.58, p = 0.018), indicating independent involvement of these factors in OSCC. One of the key discoveries of this research is the apparent reduction of the MMP-1 1G/1G and 1G/2G genotype distributions among the early onset OSCC cases under the ages of 45 years. It should be noted that the tongue was the primary site in 86.2% of these early onset cases. This could suggest the specific carcinogenic mechanisms, i.e. specific carcinogenic stimulations and/or genetic factors in the tongue. Conclusion: Since the 2G allele is a majority of the MMP-1 genotype in the general population, it seems to act as a genetic pre-condition in OSCC development. However this report suggests a crucial impact of the MMP-1 2G allele in the early onset OSCC. [ABSTRACT FROM AUTHOR]

Differential gene expression was examined in human neutrophils stimulated with lipopolysaccharide from Porphyromonas gingivalis (P. gingivalis-LPS) using RNA fingerprinting by arbitrarily primed polymerase chain reaction (RAP-PCR). LI'S from Eacherichia coil (E. coli-LPS) was used as control. More than 200 differently expressed transcripts were found in 8 subjects showing differential regulation at the transcriptional level. Densitometric analyses revealed that 42-100 genes were upregulated, while 53-116 genes were downregulated by P. gingivalis-LPS compared with E. coli-LPS. The results of sequencing identification showed the presence of supervillin (SVIL) and vascular endothelial growth factor (VEGF) genes in the clones which were upregulated by P. gingivalis-LPS. Consequently. semiquantitative analyses proved that the level of mRNA for SVIL and VEGF were significantly higher in P. gingivalis-LPS-stimulated neutrophils than in other bacterial (E. coli, Actinobacillus actinomycetemcomitans. Prevotella in intermedia) LPS- or synthetic lipid A-stimulated neutrophils. Our findings suggest that an elevated mRNA expression for SVIL could be associated with impaired function of neutrophils when stimulated by P. gingivalis-LPS. Further, the VEGF rnRNA over-expression might be related to the pathogenesis of P. gingivalis-associated periodontitis. The RAP-PCR technique used in this study enabled us to identify a number of P. gingivalis-LPS regulated genes which hitherto have not been reported. [ABSTRACT FROM AUTHOR]

This study presents the exact cell types and localization of tissue inhibitors of metalloproteinases (TIMPs) production sites in periodontal diseased gingiva by means of in situ hybridization. Gingival tissue specimens were fixed, embedded and hybridized in situ with specific digoxigenin-labeled cRNA probes (386 and 496 bp). TIMP-1 and -2 mRNAs were expressed on macrophages, mononuclear cells, capillary endothelial cells and some fibroblasts throughout the gingival tissue. In periodontitis. TIMP-1 and -2 mRNA-expressing cells showed significantly different localization. lIMP-1 mRNA was broadly observed in the gingival connective tissue while TIMP-2 mRNA was predominantly expressed in the connective tissue adjacent to the pocket epithelium (p<0.01 ). Fewer TIMPs mRNA were observed in minimal gingivitis than in periodontitis. especially in the middle zone of gingival tissue. Thus. TIMP-l and TIMP-2 mRNA was detected differentially and site-specifically in periodontal diseased gingival tissue. [ABSTRACT FROM AUTHOR]

Background: The effectiveness of an erbium-doped: yttrium, aluminum and garnet (Er: YAG) laser (EYL) for the treatment of peri-implant disease (PID) remains unclear. The aim of this study was to compare non-surgical EYL therapy for PID with locally delivered minocycline hydrochloride (MC) ointment therapy by evaluating clinical, microbiological, and biochemical markers., Material and Methods: Thirty-seven patients with PID were randomly assigned to either the EYL group (n = 18) or the MC group (n = 19). The clinical, microbiological, and biochemical markers at baseline and at 1 and 3 months after treatment were compared between the two groups. Subgingival plaque and peri-implant crevicular fluid (PICF) were collected from the diseased pockets., Results: In the EYL group, probing pocket depth (PPD) was significantly decreased after treatment when compared with baseline. On the other hand, in the MC group, there was no significant decrease in PPD after treatment. Specific bacteria associated with PID were not determined. The counts of both Gram-positive and -negative species did not significantly decrease in the EYL group at 3 months after treatment. In the MC group, the counts of almost all bacterial species were significantly decreased after treatment. Biochemical marker analysis of PICF revealed significantly lower levels of metalloproteinase (MMP)-9 in the EYL group, as compared with the MC group at 3 months after treatment ( p = 0.009)., Conclusions: Non-surgical therapy with an EYL for PID was clinically effective, with decreased MMP-9 levels in PICF, which may lead to reduced peri-implant tissue destruction. Key words: Er: YAG laser; peri-implant disease; biomarker; peri-implant crevicular fluid., Competing Interests: Conflict of interest statement: The authors have declared that no conflict of interest exist.