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Biomedical subjects

M Kanematsu

Publications and source records attributed to M Kanematsu.

At least 37 records · Page 2Linked to original sources
PubMed2000

Single breath-hold T2-weighted MR imaging of the liver: value of single-shot fast spin-echo and multishot spin-echo echoplanar imaging.

OBJECTIVE: The objective of our study was to evaluate the efficacy of single breath-hold T2-weighted MR imaging for detection of focal hepatic lesions. MATERIALS AND METHODS: T2-weighted MR images were retrospectively reviewed from 51 patients with 85 solid and 59 nonsolid lesions using the following four sequences: conventional spin-echo, respiratory-triggered fast spin-echo, single-shot fast spin-echo, and multishot spin-echo echoplanar imaging. Images were reviewed on a hepatic segment-by-segment basis; T2-weighted images of a total of 408 hepatic segments were reviewed separately and independently for solid and nonsolid lesions by four radiologists. Quantitative, qualitative, and receiver operating characteristic analyses were performed. RESULTS: For solid lesions, no significant differences were seen among the lesion-to-liver contrast-to-noise ratios with the four sequences. In terms of solid lesion detection, no significant difference was seen between the diagnostic accuracy of multishot spin-echo echoplanar (Az = 0.90) and respiratory-triggered fast spin-echo (Az = 0.91) imaging, which showed the best performance of the four sequences. For nonsolid lesion detection, respiratory-triggered fast spin-echo and single-shot fast spin-echo imaging were judged the best (Az = 0.94). CONCLUSION: Breath-hold single-shot fast spin-echo and multishot spin-echo echoplanar sequences can be substituted for conventional spin-echo and respiratory-triggered fast spin-echo T2-weighted sequences.

Adult↗
PubMed2000

[Usefulness of dynamic MR mammography for diagnosis of axillary lymph node status in breast cancer patient].

A retrospective study was performed to evaluate whether dynamic MR imaging is useful for the diagnosis of axillary lymph node metastases from breast cancer. Thirty-five patients with breast cancer were scanned and 147 lymph nodes were detected and compared with pathological nodal status. The parameters were the long axis dimension, the short axis dimension, the long-to-short axis (L/S) ratio, the shape, the contrast enhancement ratio (CER), the CER of lymph node-to-primary tumor (L/P) ratio. All parameters had significant differences between metastatic and normal nodes and there was a positive correlation between the CER of primary breast tumors and metastatic nodes. Multivariate analysis identified three parameters: the shape, the CER (1st phase), the L/P ratio (1st phase). ROC analysis revealed the shape and CER are superior in diagnostic performance to L/P ratio. If the shape and CER (1st phase) 60% and above are employed as criteria, the sensitivity, the specificity, the accuracy and the positive and negative predictive value were 86.0%, 78.4%, 81.0%, 67.2% and 91.6%, respectively. This method gives us useful information about the evaluation of axillary lymph node status preoperatively.

Adult↗
PubMed1999

Fat-suppressed T2-weighted MR imaging of hepatocellular carcinoma and metastases: comparison of conventional spin-echo, fast spin-echo, and echoplanar pulse sequences.

The purpose of our study was to compare the diagnostic accuracy of fat-suppressed T2-weighted magnetic resonance (MR) images obtained with conventional spin-echo (SE), respiratory-triggered fast SE, and breath-hold multishot SE echoplanar (EP) sequences for the detection of hepatocellular carcinoma and metastases. Images obtained with the three sequences in 17 patients (15 with cirrhosis) with 31 hepatocellular carcinomas and 14 patients with 45 metastases were retrospectively analyzed. Image review was conducted on a segment-by-segment basis; in all, 248 liver segments were reviewed separately and independently for detection of solid, malignant lesions. Diagnostic accuracy was evaluated with receiver-operating-characteristic (ROC) curve analysis. Diagnostic accuracy for hepatocellular carcinoma as determined by ROC curve analysis was better by a statistically significant amount for conventional SE (Az = 0.95) images when compared with respiratory-triggered fast SE (Az = 0.83, P < 0.05) and breath-hold multishot SE EP (Az = 0.80, P < 0.05) images. Conventional SE MR sequences should not be replaced with respiratory-triggered fast SE or breath-hold multishot SE EP sequences for T2-weighted MR imaging of patients with hepatocellular carcinoma in cirrhosis, unless sufficient contrast-enhanced dynamic MR imaging is subsequently performed.

Adult↗
PubMed1999

Potential utility of magnetic resonance cholangiography in the management of endoscopic biliary drainage tubes.

An 80-yr-old woman with advanced hilar cholangiocarcinoma underwent a placement of endoscopic biliary drainage (EBD) tube from the common hepatic to common bile duct through the stricture. Magnetic resonance cholangiography clearly demonstrated the later dislocation and obstruction of the EBD tube. The present case suggests that magnetic resonance cholangiography may be a potentially useful tool in the management of EBD tubes.

Aged↗
PubMed1999

Focal hepatic lesion detection: comparison of four fat-suppressed T2-weighted MR imaging pulse sequences.

PURPOSE: To evaluate fat-suppressed T2-weighted magnetic resonance (MR) imaging with conventional spin-echo (SE), breath-hold fast SE, respiratory-triggered fast SE, and breath-hold multishot SE echo-planar sequences for the detection of focal hepatic lesions. MATERIALS AND METHODS: Fat-suppressed T2-weighted MR images obtained with the four sequences in 55 patients with 81 solid and 129 nonsolid lesions were retrospectively analyzed. Image review was conducted on a segment-by-segment basis; a total of 440 liver segments were reviewed separately for solid and nonsolid lesions by three independent radiologists. Diagnostic accuracy was evaluated with receiver operating characteristic analysis. RESULTS: The mean lesion-to-liver contrast-to-noise ratio was highest on the multishot SE echo-planar images of both solid and nonsolid lesions. Fat-suppressed respiratory-triggered fast SE images had significantly better (P < .05) or comparative detectability of both solid and nonsolid lesions compared with the other types of images. Image quality was best on the respiratory-triggered fast SE images. CONCLUSION: Fat-suppressed respiratory-triggered fast SE imaging should replace fat-suppressed conventional SE imaging as a standard T2-weighted imaging examination in the detection of focal hepatic lesions.

Adipose Tissue↗
PubMed1999

Detection of hepatocellular carcinoma: comparison of low- and high-spatial-resolution dynamic MR images.

OBJECTIVE: The purpose of our study was to compare the diagnostic performance of low- and high-spatial-resolution gadolinium chelate-enhanced triphasic dynamic gradient-recalled echo (GRE) MR images in the detection of hepatocellular carcinoma. MATERIALS AND METHODS: Triphasic dynamic MR images obtained with low (256 x 128) and high (512 x 224) image matrices in 28 patients with 65 hepatocellular carcinomas (HCCs) were retrospectively analyzed. Image review was conducted on a segment-by-segment basis; a total of 215 liver segments, including 56 segments with tumor burden, were reviewed for the presence of HCC by three independent radiologists. Detectability was evaluated with relative sensitivity, specificity, and receiver operating characteristic (ROC) analysis. Image quality was evaluated with rank order analysis. RESULTS: Relative sensitivity was statistically significantly better with high-spatial-resolution images than with low-spatial-resolution images (p < .005). Relative specificity was statistically significantly better with low-spatial-resolution images than with high-spatial-resolution images (p < .001). Diagnostic accuracy determined by ROC curve analysis was marginally higher with high-spatial-resolution (area under ROC curve [Az] = .97) than with low-spatial-resolution (Az = .94, p < .09) images. Image quality was statistically significantly better with high-spatial-resolution images (p < .005). CONCLUSION: High-spatial-resolution dynamic GRE images were superior to low-spatial-resolution images in sensitivity of detecting HCC and in image quality. Triphasic dynamic GRE imaging in the screening and follow-up programs of patients with suspected HCC should be performed using high image matrices.

Adult↗
PubMed1998

Transforming growth factor-beta stimulates the production of osteoprotegerin/osteoclastogenesis inhibitory factor by bone marrow stromal cells.

Osteoprotegerin (OPG)/osteoclastogenesis inhibitory factor (OCIF) is a recently identified cytokine that belongs to the tumor necrosis factor receptor superfamily and regulates bone mass by inhibiting osteoclastic bone resorption. The present study was undertaken to determine whether OPG/OCIF is produced in bone microenvironment and how the expression is regulated. A transcript for OPG/OCIF at 3.1 kilobases was detected in bone marrow stromal cells (ST2 and MC3T3-G2/PA6) as well as in osteoblastic cells (MC3T3-E1). Transforming growth factor-beta1 (TGF-beta1) markedly increased the steady-state level of OPG/OCIF mRNA in a dose-dependent manner, while TGF-beta1 suppressed the mRNA expression of tumor necrosis factor-related activation-induced cytokine (TRANCE)/receptor activator of NF-kappaB ligand (RANKL), a positive regulator of osteoclastogenesis to which OPG/OCIF binds. The effect of TGF-beta1 on the expression of OPG/OCIF mRNA was transient, with a peak level at 3-6 h. The up-regulation of OPG/OCIF mRNA by TGF-beta1 in ST2 cells did not require de novo protein synthesis and involved both a transcriptional and a post-transcriptional mechanism. Western blot analysis and an enzyme-linked immunosorbent assay revealed that TGF-beta1 significantly increased the secretion of OPG/OCIF protein by ST2 cells at 6-24 h. In murine bone marrow cultures, TGF-beta1 markedly inhibited the formation of tartrate-resistant acid phosphatase-positive multinucleated osteoclast-like cells in the presence of 1,25-dihydroxyvitamin D3, whose effect was significantly reversed by a neutralizing antibody against OPG/OCIF. These results suggest that TGF-beta1 negatively regulates osteoclastogenesis, at least in part, through the induction of OPG/OCIF by bone marrow stromal cells and that the balance between OPG/OCIF and TRANCE/RANKL in local environment may be an important determinant of osteoclastic bone resorption.

Animals↗
PubMed1998

Acrolein is a product of lipid peroxidation reaction. Formation of free acrolein and its conjugate with lysine residues in oxidized low density lipoproteins.

Lipoprotein peroxidation, especially the modification of apolipoprotein B-100, has been implicated to play an important role in the pathogenesis of atherosclerosis. However, there have been few detailed insights into the chemical mechanism of derivatization of apolipoproteins during oxidation. In the present study, we provide evidence that the formation of the toxic pollutant acrolein (CH2=CH-CHO) and its conjugate with lysine residues is involved in the oxidative modification of human low density lipoprotein (LDL). Upon incubation with LDL, acrolein preferentially reacted with lysine residues. To determine the structure of acrolein-lysine adduct in protein, the reaction of acrolein with a lysine derivative was carried out. Employing Nalpha-acetyllysine, we detected a single product, which was identified to be a novel acrolein-lysine adduct, Nalpha-acetyl-Nepsilon-(3-formyl-3,4-dehydropiperidino )lysine. The acid hydrolysis of the adduct led to the derivative that was detectable with amino acid analysis. It was revealed that, upon in vitro incubation of LDL with acrolein, the lysine residues that had disappeared were partially recovered by Nepsilon-(3-formyl-3, 4-dehydropiperidino)lysine. In addition, we found that the same derivative was detected in the oxidatively modified LDL with Cu2+ and that the adduct formation was correlated with LDL peroxidation assessed by the consumption of alpha-tocopherol and cholesteryl ester and the concomitant formation of cholesteryl ester hydroperoxide. Enzyme-linked immunosorbent assay that measures free acrolein revealed that a considerable amount of acrolein was released from the Cu2+-oxidized LDL. Furthermore, metal-catalyzed oxidation of arachidonate was associated with the formation of acrolein, indicating that polyunsaturated fatty acids including arachidonate represent potential sources of acrolein generated during the peroxidation of LDL. These results indicate that acrolein is not just a pollutant but also a lipid peroxidation product that could be ubiquitously generated in biological systems.

Acrolein↗
PubMed1998

Protein-bound acrolein: potential markers for oxidative stress.

Acrolein (CH2==CH---CHO) is known as a ubiquitous pollutant in the environment. Here we show that this notorious aldehyde is not just a pollutant, but also a lipid peroxidation product that could be ubiquitously generated in biological systems. Upon incubation with BSA, acrolein was rapidly incorporated into the protein and generated the protein-linked carbonyl derivative, a putative marker of oxidatively modified proteins under oxidative stress. To verify the presence of protein-bound acrolein in vivo, the mAb (mAb5F6) against the acrolein-modified keyhole limpet hemocyanin was raised. It was found that the acrolein-lysine adduct, Nepsilon-(3-formyl-3, 4-dehydropiperidino)lysine, constitutes an epitope of the antibody. Immunohistochemical analysis of atherosclerotic lesions from a human aorta demonstrated that antigenic materials recognized by mAb5F6 indeed constituted the lesions, in which intense positivity was associated primarily with macrophage-derived foam cells and the thickening neointima of arterial walls. The observations that (i) oxidative modification of low-density lipoprotein with Cu2+ generated the acrolein-low-density lipoprotein adducts and (ii) the iron-catalyzed oxidation of arachidonate in the presence of protein resulted in the formation of antigenic materials suggested that polyunsaturated fatty acids are sources of acrolein that cause the production of protein-bound acrolein. These data suggest that the protein-bound acrolein represents potential markers of oxidative stress and long-term damage to protein in aging, atherosclerosis, and diabetes.

Acrolein↗