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Biomedical subjects

Y Yamaguchi

Publications and source records attributed to Y Yamaguchi.

At least 127 records · Page 7Linked to original sources
PubMed2001

CD45RC gammadelta T-cell infiltration is associated with immunologic unresponsiveness induced by prior donor-specific blood transfusion in rat hepatic allografts.

Little is known regarding the role of gammadelta(+) T cells in organ transplantation. We previously reported that immunologic unresponsiveness is induced by prior donor-specific blood transfusion (DST) in rat hepatic allografts. We investigated the phenotype and distribution of gammadelta(+) T cells in the hepatic allograft, spleen, and peripheral blood of recipient rats with immunologic unresponsiveness induced by DST. gammadelta(+) T cells were enumerated in allograft livers and spleens by immunostaining and in blood by flow cytometric analysis. The phenotype of gammadelta(+) T cells was determined using CD45RC isoforms derived from alternative mRNA splicing. The cytokine profile of CD45RC(+) and CD45RC(-) gammadelta(+) T cells was analyzed by reverse transcription polymerase chain reaction. The number of gammadelta(+) T cells in hepatic infiltrates in recipient rats pretreated with DST was significantly greater than in untreated animals. This correlated with significantly higher levels of gammadelta T cell receptor (TCR) mRNA in hepatic allografts of DST-treated rats as compared with untreated animals. The gammadelta(+) T cell/alphabeta(+) T-cell ratio increased in hepatic infiltrates in DST-treated recipient rats but not in untreated animals. CD45RC(-)gammadelta(+) T cells were predominantly increased in DST-treated hepatic allografts compared with untreated allografts. Most of the intestinal intraepithelial T cells were CD45RC(-)gammadelta(+). Interleukin (IL)-10 and IL-4 mRNA were detected more in CD45RC(-)gammadelta(+) T cells than CD45RC(+)gammadelta(+) T cells. CD45RC(-)gammadelta(+) T cells infiltrating liver allografts produce Th2-type cytokines and are associated with immunologic unresponsiveness induced by DST.

Acute Disease↗
PubMed2001

Endoscopic hemoclipping for upper GI bleeding due to Mallory-Weiss syndrome.

BACKGROUND: Endoscopic hemoclipping is known to be highly effective as hemostatic treatment for upper gastrointestinal bleeding. However, the efficacy and safety of hemoclipping for Mallory-Weiss syndrome (MWS) have not been reported. Thus, the aim of the present study was to assess prospectively the usefulness of endoscopic hemoclipping for MWS bleeding. METHODS: This study was conducted from January 1994 to August 1999. Hemoclipping was performed when active bleeding (spurting, streaming or oozing), visible vessels or fresh adhesive clots were found on endoscopic examination. Patients who did not have any of these findings were conservatively treated. Follow-up endoscopy was performed within 24 hours, after 5 days and between 1 and 2 months after the procedure. RESULTS: MWS was diagnosed in a total of 58 patients during the study. Hemoclipping was performed in 26 patients and was technically successful in all cases. The average number of hemoclips used was 2.8 +/- 1.6 (range 1 to 8). The number of hemoclips required for hemostasis depended on the nature of the bleeding. No complications, recurrent bleeding, or deaths resulted. Follow-up endoscopy showed no evidence of hemoclip-induced tissue injury and no impairment of Mallory-Weiss tears. CONCLUSION: Endoscopic hemoclipping provided an effective and safe modality for obtaining hemostasis when bleeding is due to MWS.

Female↗
PubMed2001

Electrovaporization using a rollerball electrode for flat or small papillary tumors of the bladder: basic study in dogs.

PURPOSE: We investigated electrovaporization of flat bladder tumors with a rollerball electrode 3 mm in diameter as a substitute for conventional transurethral resection with a cutting loop. MATERIALS AND METHODS: A basic study of the action of electrovaporization was performed in dogs. The bladder was exposed under general anesthesia in three mongrel dogs. The rollerball electrode was attached to the resectoscope and inserted into the bladder via a cystostomy. Then electrovaporization was performed with a low or high pressure on the electrode tip and a speed of about 1 cm/sec using a Force 40 generator. The cutting mode power was set at 100 W or 200 W. The effects of the rollerball and cutting loop electrodes were also examined in the coagulation mode (45 W) as a control. RESULTS: A deeper vaporization zone was obtained by using a power of 200 W in the cutting mode than with a power of 100 W, and a desiccation zone was found below the vaporization zone (VZ). The VZ was thicker with a high contact pressure than with a low contact pressure. This VZ was deeper than the tissue defect and heat-affected zone obtained using a rollerball electrode or cutting loop electrode in the 45 W coagulation mode. CONCLUSION: Although caution is required because the VZ can become too deep with excessive pressure, the rollerball electrode seems to be safer and more useful than the cutting loop electrode for resection of flat or small papillary bladder tumors.

Animals↗
PubMed2001

SPT genes: key players in the regulation of transcription, chromatin structure and other cellular processes.

Suppressor of Ty (SPT) genes were originally identified through a genetic screen for mutations in the yeast Saccharomyces cerevisiae that restore gene expression disrupted by the insertion of the transposon Ty. Classic members of the SPT gene family, SPT11, SPT12, and SPT15, encode for the histones H2A and H2B, and for TATA-binding protein (TBP), respectively. Over the past few years, molecular complexes and cellular functions in which other SPT gene products involve have been discovered through genetic and biochemical studies in yeast and several other organisms: Key regulators of transcription and chromatin structure, such as DSIF, SAGA, and FACT, all contain SPT gene products as essential subunits. In addition, accumulating evidence suggests that SPT gene products play more diverse roles, including roles in DNA replication, DNA recombination and developmental regulation. Here we review the current understanding of the functions and roles of the SPT genes, with special emphasis on the role of SPT5 in transcript elongation and in neuronal development in vertebrates.

Animals↗
PubMed2001

External doses in the environment from the Tokai-mura criticality accident.

On 30 September 1999, a criticality accident occurred at a uranium processing plant operated by JCO in Tokai-mura, Japan and the criticality remained for about 20 h. Almost all doses to the neighbouring residents were brought by neutrons and gamma rays emitted from the facility rather than fission products released to the environment. External doses in the environment were evaluated using radiation monitoring data and radiation transport calculation. A pattern of the dose rate evolution was modelled based on the records of gamma ray monitors in the JCO facilities. Relations between the ambient dose equivalent rates of neutrons/gamma rays and the distance from the facility were determined from the monitoring data obtained around the accident site. Conversion from the ambient dose equivalent to the effective dose equivalent was made assuming the energy spectra calculated by the radiation transport code, ANISN. It was estimated that the people who stayed outside the 350 m zone would receive doses of less than 1 mSv.

Gamma Rays↗
PubMed2001

Fluence to effective dose conversion coefficients for electrons with energy from 1 MeV to 100 GeV.

Fluence to organ dose and effective dose conversion coefficients have been calculated for electrons from 1 MeV to 100 GeV using an anthropomorphic phantom and the EGS4 code. The conversion coefficients were calculated for six typical irradiation geometries taking electromagnetic cascade shower and photonuclear reactions into account. The contribution to the absorbed dose due to the photonuclear reactions in energies up to 140 MeV was evaluated to be less than 0.2%. Even at energies above 140 MeV the dose contributions of the photonuclear reactions were insignificant.

Electrons↗
PubMed2001

Relations between tooth enamel dose and organ doses for electron spin resonance dosimetry against external photon exposure.

An analysis of doses to tooth enamel and to organs was carried out to develop a method that can predict the organ doses and the effective dose by electron spin resonance (ESR) dosimetry using tooth samples for external photon exposure. Absorbed dose to tooth enamel and organ doses were obtained by Monte Carlo calculations using the EGS4 code in combination with a mathematical human model with a newly defined teeth part. The calculations gave quantitative relations between tooth enamel dose and organ doses for some cases of external photon exposure. It was also found that tooth enamel dose depends more significantly on energy of incident photons than the other organ dose or the effective dose. The obtained data are to be useful for the assessment of individual dose in past exposure events by the ESR dosimetry using tooth enamel.

Air↗
PubMed2001

Percutaneous embolization of the distal pancreatic duct to treat intractable pancreatic juice fistula.

Pseudocysts and post-necrotic collections of the pancreas are sometimes treated by percutaneous drainage. In cases of post-necrotic collection, intractable pancreatic juice fistula is often formed by disruption of the main pancreatic duct in the necrotized region. We radically treated intractable pancreatic juice fistulae by selective cannulation into the distal pancreatic duct via the route for percutaneous drainage of post-necrotic collections to extinguish the exocrine function of the caudal pancreas. We performed this procedure in two patients in whom the major pancreatic duct was damaged at the body of the pancreas, which was extensively necrotic. Although mild symptoms of acute pancreatitis appeared in both patients after the first procedure, they recovered without severe side effects. Neither recurrence of pancreatic juice fistulae nor reduction of the glucose tolerance was caused by removing the exocrine function of the caudal pancreas in either patient 32 and 24 months after treatment, respectively. This method is an effective treatment modality with which to treat intractable pancreatic juice fistulae with damage of the main pancreatic duct.

Adult↗
PubMed2001

Usefulness of supernatant of pancreatic juice for genetic analysis of K-ras in diagnosis of pancreatic carcinoma.

AIMS: To ascertain whether analysis of K-ras mutations at codon 12 (KRM) in the supernatant of pure pancreatic juice (PPJ) is more useful for the diagnosis of pancreatic carcinoma (PCa) than that in sediment, the authors analyzed KRM in DNA extract from not only the sediment but also the supernatant of PPJ and compared the results. METHODOLOGY: PPJ was collected endoscopically from 19 patients with PCa and 25 patients with chronic pancreatitis (CP). DNA was extracted from the supernatant and the sediment of PPJ. Mutant allele-specific amplification (MASA) was performed for KRM analysis with the DNA extracts from these samples. RESULTS: The incidence of KRM in the supernatant of PPJ was 89% (17 of 19) in patients with PCa and 28% (7 of 25) in patients with CP, whereas that in the sediment was 79% (15 of 19) in patients with PCa and 20% (5 of 25) in patients with CP. Although there was no significant difference in KRM incidence between supernatant and sediment, the positive rate of KRM was higher in the former. Additionally, with regard to the PCa cases, KRM were found in the supernatant alone in four cases and in the sediment alone in two cases. Consequently, by a combination assay, all of the patients with PCa showed KRM in either the supernatant or sediment of PPJ. Although there was no relation between the incidence of KRM in PPJ and the location and size of tumor, and clinical stage of carcinoma in the patients with PCa, two patients with clinical stage I disease showed KRM in the supernatant. CONCLUSION: These results suggest that the positive rate of KRM in the supernatant is not lower than that in the sediment, and simultaneous analysis of KRM in the supernatant and sediment of PPJ enhances the genetic diagnosis of PCa.

Adolescent↗
PubMed2001

A non-binary direct digital synthesizer with an extended phase accumulator.

We describe a new direct digital synthesizer (DDS) in which output tuning resolution is flexibly controlled. The new DDS has an extended phase accumulator (EPA) controlled by two frequency control words; one determines the wave number within a single EPA operation cycle, and the other determines the length of the cycle. The EPA allows the DDS to provide jitter-free signals, the frequencies of which are given by arbitrary fractional expressions. (The denominator is fixed in conventional DDS that use normal phase accumulators.) Experimental results showed that the EPA worked well, allowing flexible output tuning resolution.

Journal Article↗
PubMed2001

Cutaneous wound healing: an update.

Our understanding of wound-healing mechanisms has progressed over the past decade. Wound healing is traditionally divided into three phases--the inflammatory phase, the proliferation phase, and the remodeling phase--and involves a well-orchestrated interaction among blood vessels (platelets, macrophages, neutrophils, endothelial cells, and smooth muscle cells), epidermis (keratinocytes, melanocytes, and Langerhans cells), adnexal structures (outer root sheath cells and hair dermal papilla cells), dermis (fibroblasts and myofibroblasts), nervous system (neurons), and subcutaneous fatty layers (adipocytes). We review recent discoveries of basic and clinical aspects of wound healing including several revolutions that occurred in wound management: occlusive dressing therapy, use of living skin equivalents, and topical administration of growth factors. As we previously proposed, the use of tissue substitutes and autologous epidermal sheets led to a new concept of skin grafting through the keratinocyte activation phase in the graft healing mechanism. In this review, we also discuss a representative patient who presented with plantar wounds caused by calcaneal osteomyelitis and healed by the coverage of epidermal grafting.

Humans↗
PubMed2001

[Investigation of infective endocarditis clinical isolates of methicillin resistant Staphylococcus aureus non-responsive to vancomycin].

Methicillin resistant Staphylococcus aureus (MRSA) is one of the most important strains which induce hospital and post-operative infection. In cases of infective endocarditis in which VCM was not efficacious, MRSA strains were chronologically isolated at three different times and examined with the following parameters: minimum inhibitory concentration (MIC), fractional inhibitory concentration (FIC) index, Mu 3 agar, population analysis, pulse field gel electropholesis (PFGE). The PFGE banding patterns of the three MRSA isolates were the same, therefore, it was concluded that the same strain of MRSA was selected for reduced susceptibility. A pattern of Mu 3 and Mu 50 was demonstrated under population analysis.

Endocarditis, Bacterial↗
PubMed2001

[The trend of childhood bacterial meningitis in Japan (1997.7-2000.6)].

We surveyed the epidemiology of purulent meningitis in pediatrics for 3 years between July 1997 and June 2000 in Japan and obtained the following results. The number of cases of purulent meningitis was 428, which was equivalent of 1.1-1.7 children out of 1,000 hospitalized those in pediatrics per year. The age-distribution for the infections was the highest under 1 year of age and it decreased as the age increased. Under 1 year of age, the highest distribution was observed in one month of age and under 1 month of age, the highest distribution was observed in 7 days of or younger ages. Haemophilus influenzae was the most common pathogen causing the infections, followed by Streptococcus pneumoniae, group B streptococcus, and Escherichia coli. Relationship between causing pathogens and age-distribution was as follows: group B streptococcus and E. coli were major pathogens under 4 months of age and H. influenzae and S. pneumoniae were major pathogens over 3 months of age. Susceptibility tests performed at each facility demonstrated that 25.3% of H. influenzae isolates and 38.7% of S. pneumoniae isolates were drug-resistant. Analysis of resistant genes for H. influenzae and S. pneumoniae isolates, which were stored and sent, demonstrated higher rates of resistance than those observed in susceptibility tests. These results suggest that the increase in insufficient efficacy of usual treatment with combination of ampicillin and cefotaxime is predictable against the infections. Therefore, the treatment for the infections should be reconsidered.

Female↗
PubMed2001

Factors affecting pulsatile ocular blood flow in normal subjects.

BACKGROUND: The factors that influence pulsatile ocular blood flow (POBF) were evaluated in normal subjects. METHODS: POBF was measured in 80 normal subjects using Langham OBF computerised tonometry. The effect of age, systolic and diastolic blood pressure, refractive error, intraocular pressure, and axial length on POBF was evaluated using multiple regression analysis. RESULTS: The mean (SD) POBF value was 593.3 (203.6) microl/min (range 290.7-1201.6). Of all the independent variables in the model, only the axial length was statistically significant (p = 0.008). The regression coefficient was negative, indicating that the axial length decreased with increasing POBF. CONCLUSIONS: These data suggest that, in normal subjects, the POBF decreases as axial length increases. Choroidal blood flow may decrease as the axial length increases. The axial length may therefore be a major factor affecting POBF.

Adult↗
PubMed2001

Pulsatile ocular blood flow study: decreases in exudative age related macular degeneration.

BACKGROUND: Pulsatile ocular blood flow (POBF) is a parameter for evaluating choroidal blood flow. POBF in the patients with non-exudative and exudative age related macular degeneration (AMD) was investigated. METHODS: POBF, pulse amplitude (PA), systolic and diastolic blood pressures, intraocular pressure (IOP), refractive error, and axial length were compared among 10 patients with non-exudative AMD, 11 patients with exudative AMD, and 69 age matched controls. A Langham OBF computerised tonometer was used with the participants in the sitting position to measure POBF and PA. RESULTS: No significant differences were found in age, systolic and diastolic blood pressures, IOP, or refractive error between patients with exudative and non-exudative AMD and the control subjects. In the patients with exudative AMD the POBF (median, 372.7 microl/min) and PA (median, 1.2 mm Hg) were significantly lower than in the patients with non-exudative AMD (median, 607.0 microl/min (p = 0.02) and 2.2 mm Hg (p = 0.04), respectively) and control subjects (median, 547.4 microl/min (p = 0.01) and 2.0 mm Hg (p = 0.01), respectively). CONCLUSIONS: These data show that the POBF and PA in the patients with exudative AMD are lower than in the patients with non-exudative AMD and normal subjects. Decreased choroidal blood flow may have a role in the development of choroidal neovascularisation in AMD.

Aged↗