Current Density Distribution by Ring and Diagonally Arranged Half‐Ring Electrodes in Bipolar and Overlapping Biphasic Impulse Stimulation

Background: We have studied the acute and long‐term efficacy of overlapping biphasic impulse (OLBI) stimulation for atrial pacing with VDD pacemakers and demonstrated the feasibility of DDD pacing in OLBI with diagonally arranged half‐ring (Half‐Ring) electrodes. We made two three‐dimensional computational analysis models to verify our clinical studies. Methods and Results: Model I was composed of a heart, a pacemaker, and a human body. Model II was a cube with dimensions of 20 by 20 by 20 mm quarried from Model I for the detailed study of current density distributions. Laplace's equation was solved using the finite element method and the current density J was calculated. For Model I, the distal and proximal voltages were ?10 V, 0 V in bipolar and ?5 V, +5 V in OLBI, using Ring electrodes. In Model II, the actual measurements of electrode impedances obtained from the clinical study (1,180 Ω for Ring and 630 Ω for Half‐Ring) were added to the analysis conditions. Model I showed that OLBI produced more concentrated current density distributions than those by bipolar. According to Model II, at the atrial myocardium position current density produced by Half‐Ring was larger than that by Ring electrodes, 70 μA/mm² versus 30 μA/mm² in OLBI configuration. It also indicated that even if electrode impedances were equal between Half‐Ring and Ring electrodes, the maximum current density produced by Half‐Ring would be greater than that by Ring electrodes. Conclusions: It was considered that OLBI configuration with Half‐Ring electrodes provides more effective current density distributions. (PACE 2010; 33:1063–1073)     

Renal cell carcinoma in dialysis patients: A single center experience

AIM: Renal cell carcinoma (RCC) is a life-threatening complication of end-stage renal disease with an unclear pathogenesis. We evaluated RCC developing in patients undergoing dialysis. METHODS: In 2624 patients undergoing hemodialysis or continuous ambulatory peritoneal dialysis at our hospital between July 1993 and March 2004, we performed annual screening for RCC using abdominal computed tomography and ultrasonography. Patients diagnosed with RCC underwent radical nephrectomy as well as clinical and pathologic evaluation. RESULTS: RCC was detected in 44 patients (1.68%; 31 males and 13 females). The age of RCC patients was 55.5 +/- 11.1 years. Dialysis duration before RCC diagnosis was 11.2 +/- 7.2 years. Most RCC were early stage and low stage by TNM classification, 43 patients had N0M0 RCC, whereas one had N1M0. Tumor size was 2.9 +/- 1.9 cm. The predominant histological type of RCC was common or conventional cell-type carcinoma (clear cell carcinoma and granular cell carcinoma). Of patients, 5(11.4%) had bilateral RCC, and satellite tumor lesions in RCC were detected in 13 (29.5%). In 36 patients (81.8%) RCC was accompanied by acquired cystic disease of the kidney. These patients had longer dialysis durations (P = 0.01) and smaller tumors (P = 0.048). RCC metastasized postoperatively in 4 patients (9.1%), while one (2.3%) died of cancer. CONCLUSIONS: Our dialysis patients showed a higher incidence of RCC than the general population. Prognosis was favorable because tumors were detected by screening when they were small. Therefore, periodical screening for RCC seems very important in dialysis patients.     

Possible correlation between polymorphism in the tumor necrosis factor-beta gene and the clinicopathological features of bladder cancer in Japanese patients

OBJECTIVES: In a variety of cancers, several polymorphisms of the tumor necrosis factor (TNF) genes have been reported to result in different clinical outcomes. We investigated whether a polymorphism of the TNF gene is associated with a susceptibility to bladder cancer and its disease status. METHODS: Polymorphisms in the TNF-alpha gene promoter (-308 bp) and the NcoI site in the first intron of the TNF-beta gene were analyzed in 141 Japanese patients with bladder cancer and 173 Japanese controls by polymerase chain reaction-restriction fragment length polymorphism. The correlations between the polymorphisms of the TNF genes and the clinicopathological features were analyzed. RESULTS: The number of cases and controls with TNF-alpha2 was too small to be assessable. In contrast, the TNF-beta1/2 genotype at the NcoI site in the first intron conferred a 1.71-fold increased risk of bladder cancer compared to the TNF-beta2/2 genotype. In the bladder cancer group, patients with the TNF-beta1 allele had a significantly higher risk for a high-grade tumor (grade 3) or carcinoma in situ (CIS) than those without the TNF-beta1 allele. Moreover, in the superficial bladder cancers, patients with the TNF-beta1 allele showed a significantly higher intravesical recurrence rate than those without the TNF-beta1 allele. CONCLUSION: This polymorphism in the TNF-beta gene appears to be associated with tumor occurrence and disease status, such as the tumor grade and the presence of CIS. Further study with an increased sample size is warranted.     

Longitudinal study on occlusal force distribution in lower distal-extension removable partial dentures with conus crown telescopic system

The purpose of this study was to examine longitudinal changes of the occlusal force distribution in lower distal-extension removable partial dentures with the conus crown telescopic system. Occlusal force applied to the denture and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 3 months after. The occlusal force distribution ratio to the retainers was calculated when a load of 20N was applied to the denture.
The results are summarized as follows:

• (i)

    The more posterior the loading point of occlusal force, the smaller was the ratio. When the occlusal force was applied to the most anterior artificial tooth, the ratio was 65-100% of the occlusal force.
• (ii)

    As the denture wearing time proceeded, the ratio was decreased. The smaller the ratio, the greater was the rate of its decrease.

     

Hydrolysis of various types of ester substrates with linear,cyclic and polymeric peptides containing His,Ser and Asp residues

Catalytic activities of linear, cyclic and polymeric peptides having the sequences of -Asp-ßAla-Gly-His-ßAla-Gly-(nonapeptide series) and -Asp-eAhx-Ser-eAhx-His-eAhx- (hexapeptide series) in the hydrolysis of various types of ester substrates were compared with one another and with that of poly (-His-ßAla-Gly) (Poly-3) which has no Ser or Asp residues. Hydrolytic activity of the hexapeptide series, the cyclic form in particular, was larger than that of the nonapeptide series in many cases such as in the hydrolysis of N-protected amino acid p-nitrophenyl esters (Z-Gly-ONp, Boc-Ala-ONp, Z- (l and d ) -Leu-ONp, Boc- (l and ) -Phe-ONp) and anionic 3-nitro-4-acetoxybenzoic acid ( NABA ). The activities of the polymeric peptides were generally smaller than those of the linear or cyclic peptides. None of the peptides showed the remarkable activity to the hydrophobic substrate with long chain, p-nitrophenyl laurate ( PNPL ), and they were almost inactive to bulky p-nitrophenyl trimethylacetate ( PNPTMA ) and cationic 3-acetoxy-N-trimethylanilinium iodide ( ANTI ). Enantiomer-selectivity in the hydrolysis of N-protected amino acid p-nitrophenyl esters and solvent isotope effect in the hydrolysis of p-nitrophenyl acetate ( PNPA ) are also reported.     

Nuclear magnetic resonance studies of linear,cyclic and polymeric peptides containing His,Ser and Asp residues spaced by ß alanylglycine

¹H and ¹³C nuclear magnetic resonance studies have been carried out on the linear, cyclic and polymeric peptides having a sequence of -Asp-ßAla-Gly-Ser-ßAla-Gly-His-ßAla-Gly-. From the ¹ H spectra measured at 400 MHz, the rotamer populations about side chain Cα-Cß bond for Asp, Ser and His residues were estimated at pD 5 and 8. For Asp and Ser residues, the rotamers T (trans), G and G' (gauche) had an equivalent population at both pDs, while for His residue the rotamer G' had a higher probability than the others. ¹³C chemical shift of His and Asp residues measured at a frequency 15 MHz showed a considerable change in the pD ranges 3 ? 5 and 5 ? 8, respectively, owing to the ionizable side chains. The pK value for His residue, i.e. the midpoint of the chemical shift change, corresponded fairly well to that obtained from ester hydrolytic activity measurements, supporting the previous suggestion that the ester hydrolytic reaction is mainly controlled with the imidazole group of His residue. ¹³C spin-lattice relaxation time T₁ was measured in order to investigate the molecular motion. It was found that the backbone was composed of relatively movable parts, -ßAla-Gly-, and less movable parts, Asp- Ser and His. Thisphenomenon was especially remarkable at the higher pD. The internal motion in the side chain was also investigated using the relaxation theory for the molecules undergoing the internal rotation. These results of relaxation measurements were compared with the results of conformational studies by circular dichroism measurements. The polymeric peptide composed only of -His-ßAla-Gly- sequence was also measured as a related peptide.