Biomedical subjects

Makoto Tomita

Publications and source records attributed to Makoto Tomita.

16 recordsLinked to original sources

PubMed2006

Form factor in persistent hole burning in multiple scattering optical media.

This paper presents detailed experiments on persistent hole burning in photoreactive and multiple scattering media. The dependence of the hole shape and width on the sample thickness, transport mean free path, and absorption length was measured. The experimental results show good agreement with a previously reported theoretical calculation on the basis of a diffusion approximation [Phys. Rev. E 70, 046606 (2004)].

Journal Article↗

PubMed2006

Observation of fast light in Mie scattering processes.

We observed -4.9 nsec negative group delay in the optical wave-packet propagation through a fiber taper coupled with a single Mie sphere. The observed fast light under the Mie scattering process agrees excellently with the anomalous dispersion calculated on the basis of a directional coupling theory on the undercoupling condition, which also predicts a positive group delay on the overcoupling condition.

Journal Article↗

PubMed2006

Cytapheresis for the treatment of myeloperoxidase antineutrophil cytoplasmic autoantibody-associated vasculitis: a pilot study of 21 patients.

Twenty-one patients with myeloperoxidase-antineutrophil cytoplasmic autoantibody (MPO-ANCA)-associated vasculitis were treated using cytapheresis. Of these, 17 were treated for glomerulonephritis and four were treated for pulmonary hemorrhage. The overall survival rate was 85.7% with a follow-up duration of 24.0 +/- 13.8 months. In the 17 patients with MPO-ANCA-associated glomerulonephritis, pretreatment creatinine was 3.2 +/- 1.6 mg/dL, and renal function recovered in 76.5%. Pulmonary hemorrhage was ameliorated in all four patients. Abdominal pain occurred in three of the 21 patients but symptoms resolved soon after the cytapheresis procedure was completed. No other adverse effects occurred during cytapheresis. From these results, cytapheresis can be considered a safe and effective treatment for MPO-ANCA-associated vasculitis. As for the mechanism of its action, soluble tumor necrosis factor receptor 1 (sTNFR), sTNFR2 and interleukin 1 receptor antagonist were elevated soon after cytapheresis and those levels 2 h after the cytapheresis procedure were higher than before the procedure in some cases. These elevations might be related to the efficacy of cytapheresis.

Aged↗

PubMed2005

Measurement of net group and reshaping delays for optical pulses in dispersive media.

We experimentally demonstrate the direct measurement of net group and reshaping delays for arbitrary optical pulses in dispersive media, verifying the earlier prediction of Peatross et al. [Phys. Rev. Lett. 84, 2370 (2000)]. Incoherent pulse propagation in an absorptionless system is well described by net group delay; even the medium causes a great deal of deformation in the transmitted pulse. However, in the case of phase modulated chirping pulses in a resonant absorber, the so-called superluminal or subluminal propagation velocity is strongly influenced by the reshaping delay.

Journal Article↗

PubMed2005

Evaluation of endocrine disrupting activity of plasticizers in polyvinyl chloride tubes by estrogen receptor alpha binding assay.

Polyvinyl chloride (PVC) tubing is an indispensable medical material for extracorporeal circulation therapy. However, di(2-ethylhexyl)phthalate (DEHP), a suspected endocrine disruptor, can be eluted from PVC, suggesting that an alternative material that does not contain DEHP is needed for clinical applications. First, we evaluated the endocrine disrupting risks of the plasticizers contained in PVC tubes by investigating their binding affinities for the human estrogen receptor alpha (ERalpha). Our results revealed that, while DEHP has some binding affinity for ERalpha, neither epoxidized soybean oil nor tris(2-ethylhexyl)trimellitate (an alternative to DEHP) has any affinity for ERalpha. Second, we evaluated the endocrine disrupting risks of a tube made of newly developed plasticizer-free (PF) materials. We confirmed the presence of DEHP and detected several unidentified substances in plasma stored within the PVC tube. This plasma's competitive binding affinity for ERalpha was significantly higher than that of control plasma (P < 0.01). In contrast, the profile of plasma stored in the PF tube was similar to that of the control, both in terms of high-performance liquid chromatography chromatograms and competitive binding capacity for ERalpha, suggesting that the PF tube is biocompatible and is useful for reducing the elution of substances capable of binding to ERalpha.

Chromatography, High Pressure Liquid↗

PubMed2005

Complement C4d deposition in transplanted kidneys: preliminary report on long-term graft survival.

The effects of antibody-mediated rejection on long-term graft survival have not been fully investigated. The aim of this study is to clarify the influence on long-term survival of deposition of the complement split product C4d in allografts using polyclonal anti-C4d antibody. Inclusion criteria were recipients who underwent graft biopsy during acute deterioration of graft function within the first 2 yr after transplantation. Patients whose graft did not survive more than 1 yr and who received graft from an human leucocyte antigen (HLA)-identical sibling or an ABO-incompatible donor were excluded. Among the 92 recipients investigated, 22 (23.9%) had peritubular capillary C4d deposition, 15 (16.3%) had glomerular capillary C4d deposition and seven (7.6%) had both peritubular and glomerular capillary C4d deposition. Twenty of these 22 patients revealed acute cellular rejection, including borderline changes. There was no significant relationship between pathological severity of acute rejection and presence or absence of peritubular capillary C4d deposition. Graft survival was inferior in patients with peritubular capillary C4d deposition to that in patients without C4d deposition (p = 0.0419). Graft survival in patients with glomerular C4d deposition did not differ from that in patients without C4d deposition. In conclusion, C4d deposition in peritubular capillaries has a substantial impact on long-term graft survival.

Adolescent↗

PubMed2005

Treatment with cytapheresis for antineutrophil cytoplasmic antibody-associated renal vasculitis and its effect on anti-inflammatory factors.

To evaluate the efficacy of cytapheresis for the treatment of rapidly progressive glomerulonephritis (RPGN) caused by myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis, the renal prognosis and the mortality rate at 1 year after treatment were compared between a Cytapheresis Group and a Steroid Pulse Group. The Cytapheresis Group included 10 patients who were treated with cytapheresis and oral corticosteroids. Five had granulocytapheresis with the Adacolumn (Japan Immuno Research Laboratories Co. Ltd, Takasaki, Japan) and the remaining five had leukocytapheresis with the leukocyte removal filter, Cellsorba (Asahi Medical Co. Ltd, Tokyo, Japan). The Steroid Pulse Group was comprised of 12 patients who were treated with methylprednisolone pulse therapy and oral corticosteroids. In the Cytapheresis Group, renal function recovered in 70% of the patients and the mortality rate was 10%. In the Steroid Pulse Group, renal function recovered in 66.7% and the mortality rate was 33.3%, with infection as the cause of death. Total doses of corticosteroids converted to prednisolone dose during a 1 month period, ranged from 280 mg to 1226 mg in the Cytapheresis Group. On the other hand, these dosages ranged from 2375 mg to 8380 mg in the Steroid Pulse Group. These results indicated that the mortality rate by infection could be reduced by adding cytapheresis therapy. Concerning the mechanism of cytapheresis, anti-inflammatory factors such as soluble tumor necrosis factor receptor, and interleukin-10 reduced after cytapheresis. These changes might be responsible for the efficacy of cytapheresis. In conclusion, cytapheresis is thought to be one of the effective treatments for RPGN caused by MPO-ANCA-associated vasculitis, reducing the levels of anti-inflammatory factors.

Adrenal Cortex Hormones↗

PubMed2004

Time development of a persistent hole burning in multiple-scattering media.

We investigated the time development of persistent hole burning in photoreactive and multiple-scattering media. In this hole burning, a writing laser beam recodes the volume speckle pattern inside the medium through the photoreactive process, and then the luminescence intensity excited by a reading beam is measured as a function of the frequency or wave vector difference between the writing and reading beams. The time development reflects the statistics of the intensity fluctuations in the speckle inside the medium. One of the striking results is that the maximum hole depth is approximately 0.26 . We distinguish three types of samples according to the geometric configurations and the photoreactive processes and discuss the hole shape, hole width, and the depth during time development. Hole burning experiments were also performed using a spiropyran derivative photochromic dye. The experimental results showed good agreement with the theory.

Journal Article↗

PubMed2004

Speckle correlation measurement in a disordered medium observed through second-harmonics generation.

We examined speckle correlation in a disordered medium consisting of LiNbO3 corpuscles, by observing the total intensity of the second-harmonics (SH) light generated by angular correlated two excitation beams. The total SH intensity showed a correlation peak at theta approximately 0, where theta was the angle between two excitation beams, and decreased as theta was increased. The observation could be understood as the effect of the constructive interference between two volume speckle patterns produced by the excitation beams inside the medium, and the peak could reflect the mutual correlation between two patterns. The experimental results showed good agreements with a theoretical analysis based on a diffusion approximation.

Journal Article↗

PubMed2004

Suppression of parathyroid hormone secretion in CAPD patients by intraperitoneal administration of Maxacalcitol.

BACKGROUND: Maxacalcitol (22-oxacalcitriol; OCT) is a novel vitamin D analogue. In previous clinical studies, OCT was administered three times a week to hemodialysis patients with refractory secondary hyperparathyroidism (2HPT), in whom it acted by inhibiting parathyroid hormone secretion, as well as causing mildly elevated serum calcium. However, intravenous injection of OCT, which requires frequent visits to the outpatient clinic, degrades the quality of life of patients with continuous ambulatory peritoneal dialysis (CAPD) who otherwise visit the clinic only once or twice per month. In the present study, we investigated whether transperitoneal absorption of OCT inhibited intact parathyroid hormone (i-PTH) in CAPD patients when the OCT was added to the peritoneal dialysis fluid. METHODS: Peritoneal dialysis fluid containing 20 micro g of OCT was injected into the peritoneal cavity of five CAPD patients. The serum and peritoneal fluid levels of OCT, i-PTH, calcium, and phosphate were measured before and after treatment. RESULTS: The mean concentration of OCT in peritoneal dialysis fluid rapidly decreased, from 25268.0 pg/ml at 0 h to 1694.0 pg/ml at 2 h and 44.9 pg/ml at 4 h. In contrast, the mean serum OCT level increased from the pretreatment level, which was below the detection limit of the assay, to 656.0 pg/ml at 0.5 h and a peak of 759.0 pg/ml at 1 h, and thereafter gradually decreased, to 713.8 pg/ml at 2 h and 555.8 pg/ml at 4 h. Mean i-PTH significantly decreased, to 83.9% of the baseline level, at 1 h (P < 0.05) and thereafter stayed at around 90%. No consistent trends in calcium and phosphate levels were observed in the five patients. CONCLUSIONS: By injecting OCT into the peritoneal cavity, i-PTH levels could be significantly decreased. These findings indicate the therapeutic efficacy of intraperitoneal administration of OCT for CAPD patients.

Adult↗

PubMed2004

Efficacy of granulocytapheresis and leukocytapheresis for the treatment of microscopic polyangiitis.

We evaluated the efficacy of granulocytaperesis and leukocytapheresis for the treatment of rapidly progressive glomerulonephritis (RPGN) and lung hemorrhage caused by microscopic polyangiitis. Three patients with RPGN were treated by granulocytapheresis (GCAP) and five patients with RPGN were treated by leukocytapheresis (LCAP). The prednisolone dose was 0.4 +/- 0.2 g/kg/day (mean +/- SD; range 0.2-0.8 g/kg/day). Pre-treatment serum creatinine was 3.2 +/- 1.4 mg/dL (1.4-5.1 mg/dL). The patients were followed for a mean period of 15 +/- 6 months (6-23 months). Renal function improved in five of the eight RPGN patients. Three lung hemorrhage episodes in two different patients were treated with GCAP and one lung hemorrhage episode was treated with LCAP combined with various doses of corticosteroids. All four lung hemorrhage episodes were ameliorated. We concluded that combined therapy of GCAP or LCAP and corticosteroids is effective for the treatment of RPGN and lung hemorrhage due to microscopic polyangiitis.

Aged↗

PubMed2003

Estimation of haplotype frequencies, linkage-disequilibrium measures, and combination of haplotype copies in each pool by use of pooled DNA data.

Inference of haplotypes is important for many genetic approaches, including the process of assigning a phenotype to a genetic region. Usually, the population frequencies of haplotypes, as well as the diplotype configuration of each subject, are estimated from a set of genotypes of the subjects in a sample from the population. We have developed an algorithm to infer haplotype frequencies and the combination of haplotype copies in each pool by using pooled DNA data. The input data are the genotypes in pooled DNA samples, each of which contains the quantitative genotype data from one to six subjects. The algorithm infers by the maximum-likelihood method both frequencies of the haplotypes in the population and the combination of haplotype copies in each pool by an expectation-maximization algorithm. The algorithm was implemented in the computer program LDPooled. We also used the bootstrap method to calculate the standard errors of the estimated haplotype frequencies. Using this program, we analyzed the published genotype data for the SAA (n=156), MTHFR (n=80), and NAT2 (n=116) genes, as well as the smoothelin gene (n=102). Our study has shown that the frequencies of major (frequency >0.1 in a population) haplotypes can be inferred rather accurately from the pooled DNA data by the maximum-likelihood method, although with some limitations. The estimated D and D' values had large variations except when the /D/ values were >0.1. The estimated linkage-disequilibrium measure rho2 for 36 linked loci of the smoothelin gene when one- and two-subject pool protocols were used suggested that the gross pattern of the distribution of the measure can be reproduced using the two-subject pool data.

Algorithms↗

PubMed2003

Focal segmental sclerotic lesions of the glomerulus in transplanted kidneys assessed using computerized image analysis.

Mechanisms responsible for the development of focal segmental sclerotic lesions of the glomerulus (FSGS lesions) in transplanted kidneys were investigated by morphometric analysis. The mean glomerular area and the interstitial area were measured using computerized image analysis to compare implantation biopsies (so-called 1-h biopsies; 1Bx) with later biopsies (episode Bx; EBx) that had been taken for diagnostic purposes to identify the cause of deteriorating renal function. Groups of patients with (group A, n = 15) or without (group B, n = 10) FSGS lesions were compared. Twelve of 15 in group A and all in group B had lost graft function due to chronic allograft nephropathy. It was found that neither the mean glomerular area nor the interstitial area differed significantly between the two groups in either 1Bx or EBx. The interstitial area was significantly increased (P = 0.007) and the mean glomerular area tended to be increased (P = 0.085) in EBx compared with 1Bx in group A but not in group B. The serum creatinine level at the time of EBx in group A correlated with the interstitial area (P = 0.031) but not the mean glomerular area. However, there was no similar correlation in group B. In conclusion, factors for the development of FSGS lesions in transplanted kidneys may be the increase in interstitial area and possible glomerular hypertrophy following transplantation, rather than pre-existing reduced renal mass of the donor kidneys.

Adult↗

PubMed2002

Polarization-dependent laser action in a two-dimensional random medium.

We examined laser action in a two-dimensional amplifying and scattering medium consisting of random array of dye-doped plastic fiber. When the excitation pulse energy was increased, the parallel emission component to the fiber first reached the laser threshold showing spectral collapse, and then further increase in the excitation pulse energy resulted in the subsequent laser action in the perpendicular component. Two-beam spatial-correlation measurement was performed to examine the gain regions. It was found that the size of the gain region is different between the two polarization components. Experimental results on the threshold and the gain region are discussed on the basis of simple rate equations.

Journal Article↗

PubMed2002

Cytapheresis for the treatment of myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis: report of five cases.

To minimize the adverse effects of high-dose administration of steroids and cyclophosphamide in patients with myeloperoxidase (MPO) antineutrophil cytoplasmic antibody (ANCA), granulocytapheresis (GCAP) or leukocytapheresis (LCAP) was performed to reduce inflammation. Four patients with rapidly progressive glomerulonephritis (RPGN) and one patient with pulmonary hemorrhage due to MPO-ANCA-associated vasculitis were treated by cytapheresis. The prednisolone (PSL) dose was 0.28 +/- 0.15 mg/kg/day (mean +/- SD) (range 0.18-0.50 g/kg/day). In the 4 RPGN patients, the peak serum creatinine level was 3.7 +/- 1.9 mg/dl (range 1.7 to 5.6 mg/dl). GCAP was performed in 3 RPGN patients and in 1 pulmonary hemorrhage patient. LCAP was performed in 1 RPGN patient. In the 4 RPGN patients, renal function improved after combined therapy with cytapheresis and corticosteroids. In the pulmonary hemorrhage patient, evidence of pulmonary hemorrhage on chest computed tomography scanning diminished after combined therapy with cytapheresis and corticosteroids. Cytapheresis, when combined with a low-dose or intermediate-dose PSL regimen, is effective in the treatment of ANCA-associated vasculitis.

Aged↗

PubMed2002

[Evaluation of reticulocyte hemoglobin content, percentage of hypochromic red blood cells, and ratio of serum transferrin receptor level/serum iron level as markers of iron-deficiency erythropoiesis in patients undergoing hemodialysis].

UNLABELLED: Reticulocyte hemoglobin content(CHr), percentage of hypochromic red blood cells(%HRC, level of serum transferrin receptor(sTfR), and sTfR/serum iron ratio(sTfR/Fe) were measured in 132 hemodialysis patients. On univariate analysis, CHr was positively correlated with serum amyloid A(SAA) and negatively correlated with Kt/V. %HRC showed a positive correlation with the recombinant human erythropoietin(rHuEPO) dosage. The dependency of each iron-status index on 5 variables, SAA, sFt, TS, KtN, and dose of rHuEPO administered, was determined by stepwise multiple regression analysis. CHr was influenced only by TS, while %HRC, sTfR and sTfR/Fe were influenced by both logrHuEPO dosage and TS. Patients whose hemoglobin concentration increased by more than 1 g/dl following iron supplementation were defined as Iron-Responders, and the remaining patients were defined as Iron-Nonresponders. Fifteen out of 20 patients responded to 10 consecutive intravenous administrations of 80 mg of saccharated ferric oxide at each dialysis session, while five did not. The baseline CHr was significantly lower in Iron-Responders than Iron-Nonresponders. The baseline %HRC, sTfR, and sTfR/Fe were significantly higher in Iron-Responders than Iron-Nonresponders. The baseline CHr, %HRC, and sTfR/Fe were correlated with the degree of change in Hb concentration at 4 weeks of iron supplementation. The absolute change in CHr at 2 weeks of iron supplementation was positively correlated with the absolute change in Hb concentration over the first 4 weeks. CONCLUSION: (1) In assessing the iron metabolic status of dialysis patients, CHr, %HRC, and sTfR/Fe were unique indices compared with the ordinary indices, particularly in diagnosing the functional iron deficiency state. (2) CHr was a valuable marker of iron deficiency anemia and could predict the degree of increase in Hb level following iron supplementation. (3) The %HRC and sTfR/Fe seemed to reflect both erythropoiesis induced by rHuEPO and the iron supply to erythropoietic cells.

Adult↗