Biomedical subjects

R Yamada

Publications and source records attributed to R Yamada.

At least 55 records · Page 3Linked to original sources

PubMed2001

Clinical studies on the visualization of gastric lesions using virtual CT endoscopy.

OBJECTIVE: We evaluated the clinical usefulness of virtual CT gastroendoscopy (VCTGE). METHODS: The subjects were 124 patients with endoscopically identified gastric lesions. VCTGE images were obtained using a GE-Navigator. We evaluated VCTGE in the visualization of gastric lesions for their presence and morphology. RESULTS: The detection rate of all gastric lesions by VCTGE was 76% (94 of 124 patients). The smallest detectable early gastric cancer was II c measuring 10 x 8 mm. The detection rates of each gastric lesion by VCTGE were 73% in early gastric cancer, and 90% in advanced gastric cancer. VCTGE imaging in the advanced gastric cancer was good in 12 (30%), fair in 25 (60%) and poor in 4 (10%). VCTGE imaging in early gastric cancer was good in 20 (46%), fair in 12 (27%) and poor in 12 (27%). The significance P level was 0.005 between the evaluation of the imaging of advanced and early gastric cancer. CONCLUSIONS: VCTGE visualized the characteristics of diverse gastric lesions and was considered useful for the detection and the diagnosis of these lesions.

Adult↗

PubMed2001

Fast MR imaging and ultrafast MR imaging of fetal central nervous system abnormalities.

The aims of this study were two: (1) to compare the efficacy of fast MRI (breath-hold fast spin-echo T2-weighted and fast gradient-echo T1-weighted sequence) and ultrafast MRI (half-Fourier acquisition single-shot turbo spin-echo sequence) in evaluation of fetal central nervous system (CNS) abnormalities at late gestational age, and (2) to compare the capability of fast MRI and ultrafast MRI to assess fetal CNS abnormalities with that of prenatal ultrasonography (US). Forty-nine women with fetuses at gestational ages of 26-39 weeks underwent fast MRI (29 patients) or ultrafast MRI (20 patients). In detection of motion artifact, visualization of the lateral and 4th ventricles, and differentiation between gray and white matter in cerebral hemispheres, ultrafast MRI was significantly superior to fast MRI (p< 0.0001, Mann-Whitney U test). In 25 of 43 cases, US and MR diagnoses were the same and consistent with postnatal diagnosis. In 10 of 43 cases, MRI demonstrated findings additional to or different from those of US, and MR findings were confirmed postnatally. MRI, particularly ultrafast MRI, is useful for demonstrating CNS abnormalities in situations in which US is suggestive but not definitive.

Anencephaly↗

PubMed2001

Installation and experience of an automatic scheduling system for multiple diagnostic examinations: in search of maximum utilization of regional health care resources.

We installed a scheduling system that optimally schedules multiple appointments for various diagnostic examinations for a patient based on patient characteristics, disease characteristics and conditions, characteristics of diagnostic examinations, possible interactions between two successive examinations, and features and availability of diagnostic equipment. The system consists of four client terminals, 12 laboratory terminals, and one server. After the run-in period, the system started operation in July 2000. A total of 14353 examinations involving 11447 patients were managed over 7 months. On average, approximately 82 patients per day underwent approximately 103 examinations. On average, 16.1 patients a day requested 2 or more examinations in a scheduling session (approx. 2.3 examinations/patient; maximum 5 examinations for a single patient). After reading the request sheet(s) (OCR sheet(s)), suggested time/date slots of examination(s) were displayed on the client terminal within 10 seconds. The average time required for a patient to establish his or her schedule was approximately 2 minutes. Thus, the system greatly mitigated the load on health care professionals in scheduling appointments for examinations. In general, patients had a positive impression of the system. Furthermore, networking through these health care facilities and implementing this automatic scheduling system as a centralized appointment system can easily establish a "virtual diagnostic examination center" that fully utilizes the diagnostic equipment and staff available at community health care facilities. We estimate that approximately 30% of the diagnostic examinations in a health care facility can be referred to another facility in this cooperative system.

Algorithms↗

PubMed2001

Three-dimensional gadolinium-enhanced MR angiography of the intracranial venous system.

PURPOSE: The purpose of this study was to assess the usefulness of three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiography for evaluation of the intracranial venous system. MATERIALS AND METHODS: Thirty-three patients underwent 3D dynamic gadolinium-enhanced MR angiography as well as two-dimensional (2D) time-of-flight (TOF) MR venography in transverse and coronal planes and conventional catheter cerebral angiography with digital subtraction. MR venography was displayed using a maximum-intensity-projection (MIP) algorithm. The acquisition time of 3D gadolinium-enhanced MR angiography was 102 seconds, and that of 2D TOF MR venography was about 7 minutes in the transverse plane and about 9 minutes in the coronal plane. Degree of visualization of the intracranial venous system on each MR sequence was compared with that on conventional catheter cerebral angiography as a standard. RESULTS: Superficial cortical veins and the dural sinus were better visualized on 3D gadolinium-enhanced MR angiography than on 2D TOF MR venography. CONCLUSION: Three-dimensional gadolinium-enhanced MR angiography is noninvasive and very useful for imaging of the intracranial venous system. It can replace 2D TOF MR venography not only because of its short examination time but because it better demonstrates intracranial venous structures. For evaluation of the SSS, lateral sinus, sigmoid sinus and straight sinus in particular, conventional catheter angiography seems to be unnecessary.

Adult↗

PubMed2000

Recognition of 2'-deoxy-l-ribonucleoside 5'-triphosphates by human telomerase.

Telomerase is classified as one of the reverse transcriptases (RTs). To clarify whether l-enantiomers of natural 2'-deoxyribonucleoside 5'-triphosphates (dNTPs) are recognized by human telomerase, a quantitative telomerase assay based on the "stretch PCR" method was developed and used for kinetic analysis of the inhibitory effects of these compounds on the enzyme. Among the four l-enantiomers of dNTPs, l-dTTP and l-dGTP inhibited telomerase activity and the others showed slight or no inhibitory effect. Lineweaver-Burk plot analysis showed that the inhibition modes of l-dTTP and l-dGTP were partially competitive (mixed type) and competitive with the corresponding substrate dNTP, respectively. However, the K(i) values of l-dTTP and l-dGTP (21 and 15 microM) were several times larger than the K(m) values (3-6 microM). These results suggest that the active site of telomerase is not able to discriminate strictly the chirality of dNTPs, although it is more discriminatory than HIV-1 RT.

Deoxyadenine Nucleotides↗

PubMed2000

A portion of the nucleotide sequence corresponding to the N-terminal coding region of livJ is essential for its transcriptional regulation.

We investigated the regulation of the livJ and livKHMGF operons, which are involved in branched-chain amino acid high-affinity transport in Salmonella typhimurium. When livJ was fused to lacZ at the second codon of livJ to make a livJ-lacZ protein fusion, expression from the livJ promoter was not repressed even under repressing growth conditions; however, expression of an analogous construct of livK-lacZ was repressed. When livJ was fused to lacZ at the twelfth codon of livJ, the expression level under unrepressing growth conditions was elevated, resulting in apparent repressibility of the livJ-lacZ protein fusion. Expression from the livJ-lacZ operon fusion, in which livJ was fused to lacZ 159 bp downstream from the A of the start codon of livJ, was relatively normal under unrepressing growth conditions. Deletion analysis and site-directed base-substitution analysis strongly suggested that cis-acting element for regulation of livJ transcription, 5'-GGCAGGATGTATCG-3', starting at +21 and ending at +34 downstream from the A of the start codon of livJ, was present in the N-terminal coding region of livJ.

Bacterial Proteins↗

PubMed2000

Preferential inhibition of cyclooxygenase-2 by meloxicam in human rheumatoid synoviocytes.

The aim of this study was to evaluate the anti-inflammatory effect of 4-hydroxy-2-methyl-N-[5-methyl-2-thiazolyl]-2H-1, 2-benzothiazine-3-carboxamide-1,1-dioxide (meloxicam) using cultured rheumatoid synovial fibroblast-like cells (synoviocytes). Synoviocytes were treated with meloxicam in the presence or absence of interleukin-1beta. Meloxicam had no effect on both cyclooxygenase-1 and -2 expression as determined by Western blot analysis, immunohistochemical staining, and reverse transcription polymerase chain reaction (RT-PCR). Even the lower doses of meloxicam inhibited cyclooxygenase-2 activity, but only the higher doses of meloxicam inhibited cyclooxygenase-1 activity as determined by prostaglandin E(2) synthesis assay. So meloxicam had a preferential inhibitory effect of cyclooxygenase-2 relative to cyclooxygenase-1 on cultured rheumatoid synoviocytes without affecting cyclooxygenase expression. On the other hand, indomethacin had no selectivity and dexamethasone inhibited the expression of cyclooxygenase-2. Our data indicate that clinical efficacy and safety of meloxicam for rheumatoid arthritis may result from its preferential inhibition of cyclooxygenase-2 activity relative to cyclooxygenase-1 on rheumatoid synoviocytes.

Anti-Inflammatory Agents↗

PubMed2000

Inhibition of human lung cancer cell growth by the peroxisome proliferator-activated receptor-gamma agonists through induction of apoptosis.

Peroxisome proliferator-activated receptors (PPARs), members of the nuclear hormone receptors superfamily, have an important regulatory role in adipogenesis and inflammation. PPAR-gamma ligands induce terminal differentiation and growth inhibition of human breast cancer cells and prostatic cancer cells. In this study, we demonstrated that PPAR-gamma, but not PPAR-alpha, was expressed in human lung cancer cell lines by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. We also found that the synthetic PPAR-gamma agonist thiazolidinedione compounds (troglitazone) and the endogenous PPAR-gamma ligand, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), inhibited the growth of human lung cancer cells through the induction of apoptosis. However, PPAR-alpha agonist (bezafibrate) and other prostanoids (PGE(2), PGF(2alpha)) did not induce apoptosis. These findings suggest that PPAR-gamma may play an important role in the pathogenesis of lung cancer and that PPAR-gamma agonist may be useful therapeutic agents in the treatment of human lung cancer.

Apoptosis↗

PubMed2000

Selective inhibition of cyclooxygenase-2 with antisense oligodeoxynucleotide restricts induction of rat adjuvant-induced arthritis.

The effects of cyclooxygenase (COX)-2 antisense oligodeoxynucleotide (ODN) in induction of adjuvant-induced arthritis were investigated. Female Lewis rats were injected with Mycobacterium butyricum intradermally at the base of tails to induce arthritis. Synthetic 18 mer phosphorothioate ODNs corresponding to the translation initiation site of rat COX-2 mRNA were prepared. The antisense (AS), sense (S), and "scrambled" (Sc) ODNs were intraperitoneally administered. Arthropathy was evaluated with arthritis score, paw edema, and histological examination. Expression of COX-1 and -2 protein and mRNA were examined with immunostaining and reverse-transcription polymerase chain reaction, respectively. COX-2 AS ODN significantly suppressed induction of arthritis in a dose-dependent manner without severe adverse effects, whereas S and Sc ODNs did not show significant inhibitory effects. COX-2 mRNA and protein expression were also suppressed only by COX-2 AS ODN without any alteration of COX-1 expression. These data suggest that selective inhibition of COX-2 with AS ODN may have a therapeutic potency in the treatment of rheumatoid arthritis.

Animals↗

PubMed2000

Isolation of acein-2, a novel angiotensin-I-converting enzyme inhibitory peptide derived from a tryptic hydrolysate of human plasma.

We previously described a novel angiotensin-I-converting enzyme (ACE) inhibitory peptide, designated Acein-1, that was isolated from a tryptic hydrolysate of human plasma. We now report a second such inhibitory peptide, Acein-2 obtained from the same hydrolysate. The peptide was purified by gel filtration and cation exchange chromatography followed by reversed-phase gradient and isocratic high performance liquid chromatography. Acein-2 was found to be a tripeptide, Leu-Ile-Tyr, which is thought to correspond to f(518-520) of human alpha2-macroglobulin. The synthetic tripeptide showed a potent dose-dependent inhibition of ACE, with an IC(50) value of 0.82 micromol/l. Lineweaver-Burk plots suggested that Acein-2 as well as the previously described Acein-1 are non-competitive inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

Identification of 187 single nucleotide polymorphisms (SNPs) among 41 candidate genes for ischemic heart disease in the Japanese population.

To investigate whether common variants in the human genetic background are associated with pathogenesis of ischemic heart diseases, we systematically surveyed 41 possible candidate genes for single-nucleotide polymorphisms (SNPs) by directly sequencing 96 independent alleles at each locus, derived from 48 unrelated Japanese patients with myocardial infarction, including 25.8 kb 5' flanking regions, 56.8 kb exonic and 35.4 kb intronic sequences, and 1.8 kb 3' flanking regions. In this genomic DNA of nearly 120 kb, we identified 187 SNPs: 55 in 5' flanking regions, seven in 5' untranslated regions (UTRs), 52 in coding elements, 64 in introns, eight in 3' UTRs, and one in a 3' flanking region. Among the 52 coding SNPs, 26 were non-synonymous changes. Allelic frequencies of some of the polymorphisms were significantly different from those reported in European populations. For example, the Q506R substitution in the coagulation factor V gene, the so-called "Leiden mutation", has a reported frequency of 2.3% in Europeans, but we detected the Leiden mutation in none of the Japanese genomes that we investigated. The allelic frequencies of the -33A>G SNP in the thrombomodulin gene were also very different; this allele occurred at a 12% frequency in the Japanese patients that we examined, although it had been detected in none of 82 Caucasians reported previously. These data support the hypothesis that some SNPs are specific to particular ethnic groups.

3' Untranslated Regions↗

PubMed2000

Identification of 142 single nucleotide polymorphisms in 41 candidate genes for rheumatoid arthritis in the Japanese population.

Single-nucleotide polymorphisms (SNPs) can make an important contribution to our understanding of genetic backgrounds that may influence medical conditions and ethnic diversity. We undertook a systematic survey of genomic DNA for SNPs located not only in coding sequences but also in non-coding regions (e.g., introns and 5' flanking regions) of selected genes. Using DNA samples from 48 Japanese patients with rheumatoid arthritis (RA) as templates, we surveyed 41 genes that represent candidates for RA, screening a total of 104 kb of DNA (30 kb of coding sequences and 74 kb of non-coding DNA). Within this 104 kb of genomic sequences we identified 163 polymorphisms (1 per 638 bases on average), of which 142 were single-nucleotide substitutions and the remainder, insertions or deletions. Of the coding SNPs, 52% were non-synonymous substitutions, and non-conservative amino acid changes were observed in a quarter of those. Sixty-nine polymorphisms showed high frequencies for minor alleles (more than 15%) and 20 revealed low frequencies (<5%). Our results indicated a greater average distance between SNPs than others have reported, but this disparity may reflect the type of genes surveyed and/or the relative ethnic homogeneity of our test population.

Alleles↗

PubMed2000

The major immediate-early genes of human cytomegalovirus induce two novel proteins with molecular weights of 91 and 102 kilodaltons.

Mouse monoclonal antibody MAB810 is known to recognize the major immediate-early (IE) proteins, 68 kDa IE1 (IE1p68) and 80 kDa IE2 (IE2p80), of human cytomegalovirus (HCMV). Using this antibody we found that two additional proteins with higher molecular weights of approximately 91 (p91) and 102 kDa (p102) are also synthesized in HCMV-infected cells. p91 and p102 were produced in cells stably transfected with plasmid expressing IE1p68 and IE2p80, respectively, and shown to be related with IE1p68 and IE2p80, respectively, in primary amino acid sequence. Taken together, these results indicate that p91 and p102 are expressed from the IE1 and IE2 genes, respectively.

Animals↗

PubMed2000

Purification and properties of alanine racemase from crayfish Procambarus clarkii.

Fresh water crayfish Procambarus clarkii is known to accumulate D-alanine remarkably in muscle after seawater acclimation, accompanied by an increase in alanine racemase activity. We have purified alanine racemase from crayfish muscle to homogeneity. The enzyme is a monomeric protein with a molecular mass of 58 kDa. It is highly specific to alanine and does not racemize L-serine, L-aspartate, L-glutamate, L-valine and L-arginine. The enzyme shows the highest activity at pH 9.0 in the conversion of L- to D-alanine and at pH 8.5 in the reverse conversion. Properties such as amino acid sequence, quaternary structure, pyridoxal 5'-phosphate (PLP)-dependency, pH-dependency and kinetic parameters seem to be distinct from those of the microbial alanine racemases. Various salts including NaCl at concentrations around seawater level were potently inhibitory for the activity in both of L- to -D and D- to -L direction.

Alanine Racemase↗

PubMed2000

Castleman's disease of the spleen: CT, MR imaging and angiographic findings.

Since Castleman and Towne [Castleman and Towne, Hyperplasia of mediastinal lymph nodes, New Engl. J. Med. 250 (1954), 26-30] first described hyperplasia of the mediastinal lymph nodes in 1954, many cases of Castleman's disease have been reported. Lesions originating in the spleen arc extremely rare, and we here describe the imaging appearances for such a case, and discuss with a brief review of the literature.

Angiography↗

PubMed2000

Embolotherapy for venous impotence: use of ethanol.

PURPOSE: To evaluate the usefulness of embolotherapy with ethanol for the treatment of venous impotence. MATERIALS AND METHODS: Twenty-three patients with venous impotence underwent embolotherapy. The diagnosis of venous impotence was made by means of pharmacocavernosometry and cavernosography. After exposure of the deep dorsal penile vein, a intravenous catheter was inserted directly into the deep dorsal penile vein and advanced into just front of the preprostatic plexus. Fifty percent ethanol was injected through the catheter and the endpoint of the procedure was determined based on results of venography immediately after injection. The procedure was finished when lack of venous leakage was confirmed. RESULTS: In all patients, the deep dorsal penile vein was successfully exposed surgically, the sclerosing agent successfully injected, and the endpoint successfully achieved. Immediate clinical therapeutic effect (restoration of erection) was obtained in 20 cases (87%). No severe complications were observed during or after the procedure. The follow-up period was 6-50 months. Long-term therapeutic effect was confirmed for 18 of 23 patients (78%). CONCLUSION: The authors' findings suggest that this treatment had satisfactory short-term and long-term clinical results and that longer follow-up is necessary to confirm its safety.

Adult↗

PubMed2000

Familial cluster of cutaneous Mycobacterium avium infection resulting from use of a circulating, constantly heated bath water system.

We describe familial cases of cutaneous infection caused by Mycobacterium avium. A 45-year-old father, his 14-year-old son and 11-year-old daughter, among five persons in a family, presented with a 2-month history of inflammatory subcutaneous nodules and ulcerations. Histology of skin biopsy specimens showed granulomatous inflammation, and mycobacterial colonies isolated from the skin of each patient were identified as M. avium by DNA hybridization analysis. The patients were all treated successfully with combined drug therapy consisting of rifampicin, isoniazid and clarithromycin. Their lesions were purely cutaneous M. avium infection, without any visceral involvement. Neither systemic disease nor immunological impairment was detected in the family. However, they all used a circulating, constantly heated bath water system. The bath water was continuously heated to about 40 degrees C without changing the water for a few months, and M. avium was isolated from the filter of the bath tub heating unit. It is considered that this unusual familial cluster of cutaneous M. avium infection in healthy persons may have resulted from the use of contaminated bath water.

Adolescent↗

PubMed2000

Development of a DNA immunoadsorbent: coupling DNA on sepharose 4FF by an efficient activation method.

To remove anti-DNA antibodies from a patient's plasma with systemic lupus erythematosus (SLE), a DNA immunoadsorbent was developed by covalently coupling calf thymus DNA on activated Sepharose 4FF. Sepharose 4FF was activated with 5-norbornene-2,3-dicarboximido carbonochloridate (Cl-CO-ONB), which was proven to be a very effective method for preparation of affinity chromatographic adsorbents. The activation was carried out in dry acetone using 4-(dimethylamine)pyridine (DMAP) and triethylamine (TEA) as catalysts at 4 degrees C or at room temperature. The coupling of DNA to the activated support was investigated as a function of pH, temperature, time, concentration of DNA, and activation level. It was found that the pH for optimal coupling is 3.0, and the amount of coupled DNA increases with an increase either in the concentration of DNA or the activation level. The maximum amount of coupled DNA could reach 1.0 mg DNA/ml support. The incubation of 5 to 20 ml of SLE plasma with 1.0 ml of adsorbent resulted in an 80 to 90% decline in the anti-DNA antibody level. Nonspecific adsorption for normal IgG and total protein is less than 15%.

Acetone↗