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Masaaki Seki

Publications and source records attributed to Masaaki Seki.

12 recordsLinked to original sources
PubMed2006

Identification of two subpopulations of Bacillus Calmette-Guérin (BCG) Tokyo172 substrain with different RD16 regions.

Two types of colonies with different morphologies (smooth: S and rough: R) formed when Bacillus Calmette-Guérin (BCG) Tokyo172 substrain was cultured on Middlebrook 7H10 agar medium, and their genotypes were analyzed by multiplex PCR on five RD regions and SenX3-RegX3. In most cases these two colony types had different genotypes, i.e., S colonies showed a characteristic 22 bp deletion in Rv3405c of the RD16 region (type I), and R colonies did not have this deletion (type II) similar to many other BCG substrains. Thus, there was a strong relationship between colony morphology and genotype. Both genotypes were found in every Tokyo172 preparation tested, including the seed lot for production, the origin of seed lot from the 1960s and ATCC BCG Japan. Type I was always in the majority. It was suggested that types I and II constituted independent subpopulations within the Tokyo172 substrain. Type I was shown to have a growth advantage over type II both on culture media and in mice organs.

Animals↗
PubMed2006

Epididymo-orchitis caused by intravesically instillated bacillus Calmette-Guérin: genetically proven using a multiplex polymerase chain reaction method.

The intravesical instillation of bacillus Calmette-Guérin (BCG) is a standard therapy for superficial bladder carcinoma. Tuberculosis-like inflammation in the genitourinary tract is a serious complication of BCG. It can occur after a long interval from the cessation of the intravesical BCG therapy. If inflammation occurs, it is necessary to test whether the BCG strain has caused it or another mycobacterium species has. However, there has never been a report that proves BCG causes the inflammation, because BCG is difficult to differentiate from other strains of Mycobacterium bovis and other members of the Mycobacterium tuberculosis complex by conventional tests, including regular polymerase chain reaction (PCR). We first present a case of epididymo-orchitis, which developed 31 months after the cessation of BCG therapy, detected using a multiplex PCR method as having been caused by BCG. Our report illustrates the efficacy of this method to detect the responsible microbe that is thought to be transmitted from the instillated BCG strain.

Administration, Intravesical↗
PubMed2006

[Optic nerve atrophy after vitrectomy for diabetic retinopathy: its systemic and local risk factors].

PURPOSE: To evaluate the incidence and risk factors of optic nerve atrophy after vitrectomy for diabetic retinopathy. SUBJECTS AND METHODS: Clinical charts of 48 eyes of 40 patients who underwent vitrectomy for diabetic retinopathy were retrospectively reviewed. The relationship between postoperative optic nerve atrophy and patients' physical condition was statistically analyzed. RESULT: Postoperative optic nerve atrophy, distinct from glaucomatous optic nerve atrophy, occurred in 5 eyes (10.4%). Its incidence was correlated with higher plasma creatinine concentration (p=0.001), proliferative diabetic retinopathy (p= 0.046), and retinal white vessel formation (p= 0.007). Maintenance of the best postoperative visual acuity was difficult in the patients with optic nerve atrophy. CONCLUSION: Patients with proliferative diabetic retinopathy accompanied by renal dysfunction were at high risk of optic nerve atrophy after vitrectomy.

Adult↗
PubMed2005

Modified multiplex PCR for identification of Bacillus Calmette-Guérin substrain Tokyo among clinical isolates.

When an adverse reaction occurs and a mycobacterial species is isolated from a person vaccinated with Bacillus Calmette-Guérin (BCG) or a patient receiving BCG immunotherapy, it is essential to identify whether the isolate is BCG or another mycobacterial species. However, differentiation of BCG from other members of Mycobacterium tuberculosis complex has been very difficult. Using several specific primer-pairs, Bedwell et al. [Bedwell J, Kairo SK, Behr MA, Bygraves JA. Identification of substrains of BCG vaccine using multiplex PCR. Vaccine 2001; 19: 2146-51] recently reported that they could distinguish BCG substrains. We modified their method to improve differentiation of Tokyo 172 from other members of the M. tuberculosis complex, and examined whether this modified method could be applied to clinical isolates. Our method clearly identified BCG substrain (BCG Tokyo 172) among clinical isolates and easily distinguished between M. tuberculosis and wild-type Mycobacterium bovis.

Adjuvants, Immunologic↗
PubMed2005

Müller Cells as a source of brain-derived neurotrophic factor in the retina: noradrenaline upregulates brain-derived neurotrophic factor levels in cultured rat Müller cells.

Müller cells, the predominant glial cells in the retina, are thought to play important roles in the survival of retinal neurons. Previous studies have demonstrated that Müller cells express brain-derived neurotrophic factor (BDNF), which has a pronounced neurotrophic effect on retinal ganglion cells. In this study, we investigated whether Müller cells express and release BDNF in culture. Reverse transcriptase-PCR, immunocytochemistry and Western blotting revealed that Müller cells produce BDNF mRNA and protein. Using the enzyme-linked immunosorbant assay, BDNF protein levels in Müller cells and their conditioned medium were quantified, demonstrating that Müller cells produce and release high levels of BDNF. Noradrenaline administration caused an upregulation of BDNF mRNA and protein expression by cultured Müller cells. These results suggest that Müller cells may act as an endogenous source of BDNF in the retina. Furthermore, induction of BDNF expression by adrenergic agonists may provide a therapeutic approach to retinal neurodegenerative disorders.

Animals↗
PubMed2004

Involvement of brain-derived neurotrophic factor in early retinal neuropathy of streptozotocin-induced diabetes in rats: therapeutic potential of brain-derived neurotrophic factor for dopaminergic amacrine cells.

Although neurotrophins have been assessed as candidate therapeutic agents for neural complications of diabetes, their involvement in diabetic retinopathy has not been fully characterized. We found that the protein and mRNA levels of brain-derived neurotrophic factor (BDNF) in streptozotocin-induced diabetic rat retinas were reduced to 49% (P < 0.005) and 74% (P < 0.05), respectively, of those of normal control animals. In addition, dopaminergic amacrine cells appeared to be degenerating in the diabetic rat retinas, as revealed by tyrosine hydroxylase (TH) immunoreactivity. Overall TH protein levels in the retina were decreased to one-half that of controls (P < 0.01), reflecting reductions in the density of dopaminergic amacrine cells and the intensity of TH immunoreactivity within them. To confirm the neuropathological implications of BDNF reduction, we administered BDNF protein into the vitreous cavities of diabetic rats. Intraocular administration of BDNF rescued dopaminergic amacrine cells from neurodegeneration and counteracted the downregulation of TH expression, demonstrating its therapeutic potential. These findings suggest that the early retinal neuropathy of diabetes involves the reduced expression of BDNF and can be ameliorated by an exogenous supply of this neurotrophin.

Amacrine Cells↗
PubMed2003

BDNF is upregulated by postnatal development and visual experience: quantitative and immunohistochemical analyses of BDNF in the rat retina.

PURPOSE: This study sought to elucidate changes in the levels and distribution of brain-derived neurotrophic factor (BDNF) in the retina throughout aging and depending on visual experience. METHODS: Protein and mRNA levels of BDNF were quantified by enzyme-linked immunosorbent assay (ELISA) and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), respectively. Levels were assayed in the retinas of rats on postnatal day (P)2, P7, and P14 (approximate time of eye opening) and at 1 month (M), 3M, 8M, and 18M of age. Changes in BDNF expression and localization in the retina were assessed by immunohistochemistry. The effect of monocular deprivation during infancy on retinal BDNF expression was also examined, by ELISA and immunohistochemistry. RESULTS: Both protein and mRNA levels of BDNF in the rat retina increased after P14. Immunohistochemical analyses revealed that the increase in BDNF protein levels occurred in retinal ganglion cells (RGCs) between P14 and 1M. BDNF immunoreactivity in Müller cell processes was observed in the inner nuclear layer at 1M, but not at P14. The levels of BDNF protein in the retinas of visually deprived eyes were lower than those of control eyes, as quantified by ELISA. Immunohistochemistry showed that BDNF immunoreactivity in RGCs was diminished by visual deprivation, whereas Müller cells were unaffected. CONCLUSIONS: These observations indicate that BDNF expression in RGCs is upregulated in an activity-dependent manner, whereas that in Müller cells is regulated only by development.

Aging↗
PubMed2002

Establishment of a novel enzyme-linked immunosorbent assay for Thy-1; quantitative assessment of neuronal degeneration.

In the central nervous system (CNS), Thy-1 is expressed predominantly on neurons and serves as a specific marker for neurons. In the present study, we established a two-site enzyme-linked immunosorbent assay (ELISA) that detects trace amounts of Thy-1 protein. Recombinant Thy-1 protein expressed in Escherichia coli was purified and used as a standard. Of the regions of the nervous system examined, the highest Thy-1 concentration was found in the striatum followed by the hippocampus, neocortex, cerebellum, spinal cord, retina and optic nerve. We found that injection of a neurotoxin, N-methyl-D-aspartate, into the vitreous cavity reduced the Thy-1 level in the retina. Thy-1 ELISA will be useful for quantitative assessment of neurodegeneration in the CNS.

Animals↗
PubMedDate not supplied

Quantitative analyses of mRNA and protein levels of neurotrophin-3 in the rat retina during postnatal development and aging.

PURPOSE: In this study, we sought to elucidate changes in the levels of neurotrophin-3 (NT-3) in the rat retina throughout postnatal development and aging. METHODS: We demonstrated NT-3 localization in the retina by immunohistochemistry. Protein and mRNA levels of NT-3 were quantified by enzyme-linked immunosorbant assay and semiquantitative reverse transcriptase-polymerase chain reaction, respectively. NT-3 protein levels were assayed in the various regions of the central nervous system. Age-associated changes in protein and mRNA levels of NT-3 in the retinas were assessed. RESULTS: NT-3-immunoreactivity localized in the ganglion cell layer, inner nuclear layer, and outer nuclear layer. NT-3 content in the retina was relatively high in the examined regions of the central nervous system. Retinal NT-3 protein levels decreased after eye opening, whereas mRNA levels were constant. Both mRNA and protein levels of NT-3 in the retinas of aged animals remained constant. CONCLUSIONS: Our observations suggest that NT-3 regulation in the retina is independent of increasing visual stimuli after eye opening. Stable expression of NT-3 in the adult retina suggests a possible role in the maintenance of the retinal environment throughout later life.

Aging↗
PubMedDate not supplied

Comparison of fornix- and limbus-based conjunctival flaps in mitomycin C trabeculectomy with laser suture lysis in Japanese glaucoma patients.

PURPOSE: To analyze the results of mitomycin C (MMC) trabeculectomy and laser suture lysis using either fornix-based (FB) or limbus-based (LB) conjunctival flaps. METHODS: Eighty-two Japanese glaucoma patients were treated by MMC trabeculectomy, with 38 eyes receiving an FB conjunctival flap and 44 eyes receiving an LB conjunctival flap. Postoperative intraocular pressure (IOP), the probability of success, and complications were compared between the FB and LB groups. RESULTS: The IOP of the FB group decreased from 21.6+/-7.90 mmHg to 9.75+/-3.23 mmHg at 12 months postoperation, and the IOP of the LB group decreased from 21.3+/-6.77 mmHg to 9.30+/-3.16 mmHg. The postoperative IOPs were similar in the two groups at all postoperative time points. A life-table analysis (Kaplan-Meier method) showed that the survival rate was similar in the two groups but tended to be lower in the early postoperative period in the FB group. Complications were similar also, with the exception of increased leakage in the FB group. CONCLUSIONS: MMC trabeculectomy results were similar between FB and LB conjunctival flaps, in agreement with previous reports. However, increased care may be warranted when an FB flap is used in MMC trabeculectomy.

Antibiotics, Antineoplastic↗
PubMedDate not supplied

The outcome of mitomycin C trabeculectomy and laser suture lysis depends on postoperative management.

PURPOSE: To verify that postoperative management affects the outcome of mitomycin C (MMC) trabeculectomy and suture lysis. METHODS: A total of 108 eyes in 108 Japanese patients were treated with MMC trabeculectomy. They were divided into two groups based on when the operation was performed: group A, 57 eyes in 1998, and group B, 51 eyes in 2001. The results, including postoperative intraocular pressure (IOP), complications, and postoperative management, were compared between groups. In addition, they were evaluated by a Kaplan-Meier life-table analysis. RESULTS: Postoperative IOP was lower and the probability of success by life-table analysis was higher in group B than in group A. Postoperative management, including laser suture lysis and subconjunctival injection of 5-fluorouracil, was started significantly earlier in group B than in group A patients. Although more postoperative complications occurred in group B, none were severe and all were adequately managed. CONCLUSIONS: Starting postoperative management earlier, particularly laser suture lysis, may be necessary to achieve lower and longer IOP control in MMC trabeculectomy.

Antibiotics, Antineoplastic↗