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Biomedical subjects

Shuji Yamamoto

Publications and source records attributed to Shuji Yamamoto.

At least 37 records · Page 2Linked to original sources
PubMed2003

Analysis of entrance surface dose in general radiographies using body mass index classification.

Dose audit is an important topic in radiology and variations in dose attributable to sex have not been fully investigated. The primary purpose of our study was to determine the entrance surface dose (ESD) for men and women, from which we established an easy estimation equation for ESD, using the body mass index (BMI) as a variable. From April 2000 to March 2002, 15424 patients (8586 men, 6838 women; mean age, 58 years old; age range, 20 to 90 years old) were recruited in this study. Estimated equation of ESD was obtained from the dispersion data of BMI and ESD. Welch's t-test was used as the test of significance. P values evaluated levels of significance at 5%. Analysis for correlation coefficients was used for Peason's correlation coefficient test. And, we also performed a simple regression analysis. The results of the simple regression equation with BMI as variable (y: ESD [mGy], x: BMI [kg/m(2)), and the median values of ESD were as follows: for chest PA, men, 0.22, y = 0.0145 x - 0.0876, women, 0.20, y = 0.0126 x - 0.0704; for abdomen AP, men, 2.12, y = 0.2707 x - 3.7206, women, 1.65, y = 0.2561 x - 3.7989; for pelvis AP, men, 1.87, y = 0.0517 x + 0.8753, women, 1.77, y = 0.0674 x + 0.4775; for lumbar spine AP, men, 3.08, y = 0.3462 x - 4.1416, women, 2.66, y = 0.2525 x - 2.8131; and for lumbar spine lateral, men, 9.31, y = 0.6012 x - 3.7216, women, 7.42, y = 0.3147 x + 0.3384. The results of ESD had a significant difference between sexes (P < 0.05). Chest PA, abdomen AP, lumbar spine AP, and lumbar spine lateral each had a good correlation between ESD and BMI (r: 0.4 to 0.8). We successfully obtained the estimation equation using BMI as variable.

Body Mass Index↗
PubMed2002

Allelic homogeneity due to a founder mutation in Japanese patients with lattice corneal dystrophy type IIIA.

Lattice corneal dystrophies (LCDs) are caused by mutations of the transforming growth factor beta-induced gene (TGFBI, formerly betaig-h3). LCD type IIIA (LCDIIIA) has been reported mostly from Japan. In this study, we demonstrate allelic homogeneity for Japanese patients with LCDIIIA, using intragenic polymorphic markers. When exon 11 of TGFBI was analyzed, all 18 patients examined were found to be heterozygous for both a P501T mutation and an IVS10-3C --> T variation. On the other hand, none of 54 normal Japanese control subjects had the P501T, and 5 of the controls were heterozygous for IVS10-3C --> T. Haplotype analysis of the patients revealed that both P501T and IVS10-3C --> T were located on the same chromosome, and a significant linkage disequilibrium (P < 0.001, Fisher's exact probability test) was observed between LCDIIIA (P501T) and IVS10-3C --> T. When exon 8 of the gene was analyzed, all these patients possessed the "G allele" of a 1028G/A polymorphism. A significant linkage disequilibrium (P < 0.003; chi-square test) was also observed between P501T and the G allele in the patients. These results suggest that allelic homogeneity seen in Japanese patients with LCDIIIA may result from a single founder mutation.

Alleles↗
PubMed2002

The bispectral index response to tracheal intubation is similar in normotensive and hypertensive patients.

PURPOSE: To compare the hemodynamic and bispectral index (BIS) responses to tracheal intubation in normotensive and hypertensive patients. METHOD: Three minutes after induction of anesthesia with thiamylal and fentanyl, tracheal intubation was performed in 24 normotensive and 22 hypertensive patients. Heart rate (HR), mean arterial pressure (MAP), and BIS were measured every minute. RESULTS: Tracheal intubation increased HR, MAP, and BIS in both normotensive and hypertensive patients. The increase in MAP was significantly greater in hypertensive patients than in normotensive patients, but there were no differences in HR or BIS in the two groups of patients. CONCLUSION: Patients with and without hypertension exhibit the same arousal response (as measured by BIS) to tracheal intubation despite the enhanced vasopressor response in hypertensive patients.

Adult↗
PubMed2002

Monitoring of skeletal muscle oxygenation using near-infrared spectroscopy during abdominal aortic surgery.

PURPOSE: To examine the utility of near-infrared spectroscopy (NIRS) in assessing lower-leg perfusion, NIRS was performed on the calf muscles of patients who underwent abdominal aortic surgery. METHODS: Thirty patients undergoing elective infrarenal abdominal aortic surgery for abdominal aortic aneurysm (AAA group; n = 16) and aorto-occlusive disease (AOD group; n = 14) were studied. Before induction of anesthesia, NIRS probes were placed over both calf muscles, and muscle oxygen saturation (S(tO2)) was continuously monitored throughout the surgery. RESULTS: The preoperative S(tO2) value was significantly lower in the AOD group (57.0 +/- 11.2%) than in the AAA group (68.7 +/- 7.0%). In both groups, S(tO2) significantly decreased after aortic cross-clamping; the maximal ischemic value of S(tO2) in the AAA group (17.8 +/- 7.2%) was significantly lower than that in the AOD group (46.7 +/- 17.1%). The time taken to reach maximal ischemia was significantly longer in the AAA group (30 +/- 12 min) than in the AOD group (19 +/- 12 min). After release of the aortic clamp, the decreased S(tO2) returned to the preoperative level in the AAA group, whereas it increased above the preoperative value in the AOD group. CONCLUSION: NIRS performed on the calf muscles is a useful method for assessing the changes in lower-leg perfusion during and after abdominal aortic surgery.

Journal Article↗
PubMed2002

Evaluation of pulse corticosteroid therapy for vogt-koyanagi-harada disease assessed by optical coherence tomography.

PURPOSE: To evaluate the rapid effects of pulse corticosteroid therapy on the serous retinal detachment found at the acute phase of Vogt-Koyanagi-Harada disease. DESIGN: Interventional case series. METHODS: Nine Japanese patients determined to be at the acute phase of Vogt-Koyanagi-Harada disease with serous retinal detachment were treated with pulse corticosteroid therapy. Optical coherence tomography was used to follow the resolution of the retinal detachment. RESULTS: Optical coherence tomography images showed a marked decrease in the retinal detachment immediately after the first intravenous injection of corticosteroid and subsequent resolution. CONCLUSION: The rapid improvement of serous retinal detachment associated with Vogt-Koyanagi-Harada disease following pulse corticosteroid therapy supports an early therapeutic mechanism related to improved permeability of capillaries and permeability of the blood-retinal barrier rather than an anti-inflammatory or immunosuppressive action.

Acute Disease↗
PubMed2002

Two novel point mutations of the XLRS1 gene in patients with X-linked juvenile retinoschisis.

PURPOSE: To report two novel point mutations of the XLRS1 gene in two Japanese patients with X-linked juvenile retinoschisis. DESIGN: Observational case reports. METHODS: The exons, including the flanking introns of XLRS1, were amplified by polymerase chain reaction and analyzed by direct sequencing. RESULTS: One novel splice donor site mutation (IVS2 + 1g to a) and one missense mutation of exon 6 (Ala211Thr) were found. CONCLUSIONS: Genetic findings identifying mutations in the XLRS1 gene will lead to earlier and more accurate diagnosis of X-linked juvenile retinoschisis.

Base Sequence↗
PubMed2002

The effect of fentanyl on hemodynamic and bispectral index changes during anesthesia induction with propofol.

STUDY OBJECT: To investigate the changes in hemodynamics and hypnotic levels during propofol infusion and tracheal intubation with and without fentanyl. DESIGN: Randomized, double-blinded study. SETTING: Teaching hospital. PATIENTS: 40 ASA physical status I adult patients scheduled for elective surgery. INTERVENTIONS: Patients were anesthetized with either propofol (Group P; n = 20) or 2 microg/kg of fentanyl IV followed by propofol (Group PF; n = 20). Propofol was infused at 20 mg/kg/hr throughout the study, and tracheal intubation was performed 10 minutes after the start of propofol infusion. MEASUREMENT AND MAIN RESULTS: Bispectral index monitoring (BIS) progressively decreased to about 50 in both groups during infusion of propofol, but no difference was found between the two groups. After tracheal intubation, BIS significantly increased but remained below 60 in both groups. Hypertensive responses to intubation were fewer in Group PF than Group P. CONCLUSIONS: Propofol administration 20 mg/kg/hr for 10 minutes is suitable in suppressing arousal reactions to tracheal intubation, but the addition of fentanyl is required to blunt the hemodynamic responses.

Analgesics, Opioid↗
PubMed2002

Recurrence of corneal dystrophy resulting from an R124H Big-h3 mutation after phototherapeutic keratectomy.

PURPOSE: The purpose of the study was to investigate the recurrence-free interval after phototherapeutic keratectomy (PTK) in patients with corneal dystrophies resulting from an Arg124His (R124H) mutation of the Big-h3 gene. METHODS: Patients with corneal dystrophy resulting from a genetically confirmed Big-h3 R124H mutation were examined with a slit lamp. The patients were divided into two groups on the basis of the mutation genotype, and the recurrence-free interval was analyzed. RESULTS: In the 4 eyes of 3 homozygous patients, the mean (+/- standard deviation [SD]) recurrence-free interval was 9.5 +/- 3.1 months, whereas in the 7 eyes of 4 heterozygous patients it was 38.4 +/- 6.2 months. The former interval was statistically shorter than the latter (Kaplan-Meier survival analysis with log-rank test, p = 0.004). CONCLUSIONS: These results strongly suggest that the mutation genotype of Big-h3 gene determined the recurrence-free interval as well as the clinical picture after PTK. Therefore, PTK should be considered for patients with Big-h3 R124H corneal dystrophy, on the basis of the expected recurrence-free interval deduced from molecular analysis of the zygosity of the Big-h3 R124H mutation.

Adult↗
PubMed2002

Comparison of quality of multiplanar reconstructions and direct coronal multidetector CT scans of the lung.

OBJECTIVE: The purpose of this study was to compare the quality of coronal multiplanar reconstructions with the quality of direct coronal thin-section multidetector CT (MDCT) scans. MATERIALS AND METHODS: Axial multidetector CT (MDCT) scans were obtained through the entire lung in 10 normal autopsy lung specimens using an MDCT scanner. Four protocols were used: 0.5-mm collimation with a 0.5-mm reconstruction interval; 0.5-mm collimation with a 0.3-mm reconstruction interval; 1-mm collimation with a 0.5-mm reconstruction interval; and 2-mm collimation with a 1-mm reconstruction interval. Multiplanar reconstruction images with 0.5-mm slice thickness were obtained from the four types of data sets. Direct coronal thin-section CT of the same 10 autopsy lung specimens was performed using 0.5-mm scan collimation, a 0.3-mm reconstruction interval, a 25.6-cm field of view, and a 512 x 512 matrix. Two independent observers compared the image quality of each of the four coronal multiplanar reconstruction sets with that of direct coronal thin-section CT scans. The observers analyzed visualization of anatomic features and artifacts. RESULTS: The total image quality of the multiplanar reconstructions obtained from 0.5-mm collimation data with or without 0.3-mm overlapping reconstruction was equal to that of direct coronal thin-section CT scans in all 20 interpretations. The image quality of multiplanar reconstruction images from 0.5-mm collimation data either with or without overlapping reconstruction was superior to multiplanar reconstruction images obtained from 1- or 2-mm collimation scans (p < 0.01, Fisher's exact test). Stairstep artifacts in multiplanar reconstructions using 0.5-mm collimation without overlapping reconstruction were equal to those with overlapping reconstruction and were fewer than those on 1- or 2-mm collimation (p < 0.01, Mann-Whitney U test). CONCLUSION: The image quality of coronal multiplanar reconstructions from isotropic voxel data obtained using 0.5-mm collimation, with or without overlapping reconstruction, is similar to that of direct coronal thin-section CT scans.

Aged↗
PubMed2002

PAX6 mutation as a genetic factor common to aniridia and glucose intolerance.

A paired homeodomain transcription factor, PAX6, is a well-known regulator of eye development, and its heterozygous mutations in humans cause congenital eye anomalies such as aniridia. Because it was recently shown that PAX6 also plays an indispensable role in islet cell development, a PAX6 gene mutation in humans may lead to a defect of the endocrine pancreas. Whereas heterozygous mutations in islet-cell transcription factors such as IPF1/IDX-1/STF-1/PDX-1 and NEUROD1/BETA2 serve as a genetic cause of diabetes or glucose intolerance, we investigated the possibility of PAX6 gene mutations being a genetic factor common to aniridia and diabetes. In five aniridia and one Peters' anomaly patients, all of the coding exons and their flanking exon-intron junctions of the PAX6 gene were surveyed for mutations. The results of direct DNA sequencing revealed three different mutations in four aniridia patients: one previously reported type of mutation and two unreported types. In agreement with polypeptide truncation and a lack of the carboxyl-terminal transactivation domain in all of the mutated PAX6 proteins, no transcriptional activity was found in the reporter gene analyses. Oral glucose tolerance tests revealed that all of the patients with a PAX6 gene mutation had glucose intolerance characterized by impaired insulin secretion. Although we did not detect a mutation within the characterized portion of the PAX6 gene in one of the five aniridia patients, diabetes was cosegregated with aniridia in her family, and a single nucleotide polymorphism in intron 9 of the PAX6 gene was correlated with the disorders, suggesting that a mutation, possibly located in an uncharacterized portion of the PAX6 gene, can explain both diabetes and aniridia in this family. In contrast, the patient with Peters' anomaly, for which a PAX6 gene mutation is a relatively rare cause, showed normal glucose tolerance (NGT) and did not show a Pax6 gene mutation. Taken together, our present observations suggest that heterozygous mutations in the PAX6 gene can induce eye anomaly and glucose intolerance in individuals harboring these mutations.

Adolescent↗
PubMed2002

[Technical application of three-dimensional visualization and measurement for breast cancer using multidetector-row CT scanner].

This paper describes an integrated methodology that addresses the operation of 3D imaging and measurement for the diagnosis and surgical operation of breast cancer. The main system for breast CT imaging used a multi-slice CT scanner and 3D-workstation. The clinical sequence was performed in three phases with non-contrast and biphasic contrast-enhanced studies that were performed with multi-slice helical CT scanning. Acquired DICOM images were directly sent to the 3D workstation that implemented our developed functions. Four types of transfer functions (mammary skin, vessel, lymph node, and tumor) were set based on region-of-interest (ROI) measurements. After that, two types of segmentation were prepared with volumetry and measurement of the size of breast cancer. Batch processing for 3D visualization and the measurement of breast tumors was helpful for diagnosis and surgical planning.

Breast Neoplasms↗
PubMed2002

[Visualization by dynamic CT: invention of 2D-CT chronogram].

Dynamic computed tomography is one of the methods used for the functional analysis of blood flow information. We devised a simple method of visualization for dynamic CT. Re-sliced images were stacked as multi-slice images for the different acquisition times to show a continuous spatial arrangement with dynamic data. Images processed into re-sliced images termed 2D-CT Chronograms were observed in many directions and were useful for comprehending the blood flow function of the target organ. Time-density curves with motion dependency and color displays similar to those of ultrasound images are easily acquired from the 2D-Chronogram. We introduce some clinical applications of the 2-D Chronogram.

Contrast Media↗
PubMed2002

[Evaluation of the retrospective ECG-gated helical scan using half-second multi-slice CT: motion phantom study for volumetry].

ECG synchronized technique on multi-slice CT provide the thinner (less 2 mm slice thickness) and faster (0.5sec/rotation) scan than that of the single detector CT and can acquire the coverage of the entire heart volume within one breath-hold. However, temporal resolution of multi-slice CT is insufficient on practical range of heart rate. The purpose of this study was to evaluate the accuracy of volumetry on cardiac function measurement in retrospective ECG-gated helical scan. We discussed the influence of the degradation of image quality and limitation of the heart rate in cardiac function measurement (volumetry) using motion phantom.

Electrocardiography↗
PubMed2002

ABCA4 gene mutations in Japanese patients with Stargardt disease and retinitis pigmentosa.

PURPOSE: To evaluate photoreceptor cell-specific adenosine triphosphate (ATP)-binding cassette transporter (ABCA4) gene mutations in Japanese patients with Stargardt disease (STGD) and the correlation of these mutations to clinical phenotypes. METHODS: Serum was obtained from 10 unrelated Japanese patients with STGD and 96 unrelated Japanese patients with autosomal recessive retinitis pigmentosa (arRP). All 50 ABCA4 gene exons of the patients with STGD were screened for mutations by a combination of single-strand conformation polymorphism analysis and polymerase chain reaction (PCR) direct-sequencing techniques. By restriction enzyme digestion, primer extension analysis, and PCR direct sequencing techniques, the patients with arRP were screened for three segregated, presumably null ABCA4 gene mutations observed in Japanese patients with STGD. RESULTS: Three novel, presumably null mutations of the ABCA4 gene, IVS7-45_952delinsTCTGACC, IVS12+2T-->G, and 1894delA, were identified. The Arg2149stop mutation that had been found in a white patient with STGD in a prior study was also found in a Japanese patient. Two arRP-affected siblings and two unrelated patients with STGD were found to be homozygous for the same IVS12+2T-->G mutation, and three other arRP-affected siblings were carriers of the IVS12+2T-->G mutation and/or the IVS7-45_952delinsTCTGACC mutation. These three siblings with arRP showed only atrophic degeneration in the macula early after the onset of the disease, and STGD had been diagnosed. CONCLUSIONS: Three novel ABCA4 gene mutations were identified in Japanese patients with STGD and arRP. Mutations in the ABCA4 gene can cause panretinal degeneration that changes its clinical appearance from STGD to arRP over time.

ATP-Binding Cassette Transporters↗
PubMed2002

[Effect of nitrous oxide on the bispectral index during sevoflurane anesthesia].

We studied the effects of nitrous oxide on the relationship between end-tidal sevoflurane concentration and bispectral index (BIS) in patients undergoing abdominal surgery. Anesthesia was maintained with combination of epidural and sevoflurane anesthesia in air (control group; n = 15) or with 67% nitrous oxide (nitrous oxide group; n = 15). The end-tidal sevoflurane concentration was increased by 0.5% every 15 min to 3% and BIS values were recorded at each step. In both groups, sevoflurane decreased BIS values in a dose-dependent manner and the decrease in BIS reached plateau at 2% of sevoflurane. Nitrous oxide with sevoflurane caused more reduction in BIS in comparison with sevoflurane alone. The sevoflurane concentration for BIS at 50 in the nitrous oxide group (0.9 +/- 0.4%) was significantly lower than that in the control group (1.2 +/- 0.4%). The results suggest that the hypnotic effect of sevoflurane was enhanced by the addition of nitrous oxide during abdominal surgery.

Abdomen↗
PubMedDate not supplied

The use of competitive PCR for quantitation of HSV-1 DNA.

PURPOSE: Polymerase chain reaction (PCR) detects the genomic materials of etiological agents with high specificity and sensitivity. However, in herpes simplex virus type 1 (HSV-1) infection, the clinical significance of the results often poses controversy because of the subclinical viral shedding during latent infection. Quantitative PCR might provide additional information to help clinical evaluation of the results. METHODS: Virus DNA was extracted from high titer stock of human HSV-1 (FK 25) by phenol/chloroform treatment. Construct (p/HSV-1) was made by inserting the glycoprotein D gene obtained from virus DNA into p(GEM-T) vector. Competitor (p/DeltaHSV-1) was made by deleting the inner 40 bp of construct (p/HSV-1) with restriction enzyme. Competitive PCR was performed using primers that amplify the glycoprotein D gene, and a template made of a 1:1 molar mixture of HSV-1 DNA and the competitor. RESULTS: The PCR product reflected the initial template dose from 20 to 30 cycles. Minimum detection level of HSV-1 DNA was 0.01 ng. CONCLUSION: Competitive PCR can quantitate HSV-1 DNA.

DNA, Viral↗