Biomedical subjects

H Hoshi

Publications and source records attributed to H Hoshi.

At least 37 records · Page 2Linked to original sources

PubMed2001

Mr cholangiography with volume rendering: receiver operating characteristic curve analysis in patients with choledocholithiasis.

OBJECTIVE: The purpose of our study was to compare observer performances for the diagnosis of choledocholithiasis using MR cholangiography with volume-rendered, maximum-intensity-projection, and thick-section half-Fourier rapid acquisition with relaxation enhancement sequences. MATERIALS AND METHODS: The images from three types of MR cholangiography performed on 43 patients with biliary calculi were retrospectively analyzed. Image review was conducted for two anatomic compartments (upper biliary tract and common bile duct). A total of 86 compartments, including 19 with bile duct calculi, were reviewed by three independent off-site gastrointestinal radiologists. Observer performance was determined by receiver operating characteristic curve analysis. Image quality was subjectively judged by three radiologists. RESULTS: Sensitivity was higher with volume-rendered MR cholangiography (58%) than with thick-section (54%, not significant) and maximum-intensity-projection MR cholangiography (47%, p < 0.07). Specificity was higher with volume-rendered MR cholangiography (92%) than with thick-section (86%, p < 0.03) and maximum-intensity-projection MR cholangiography (88%, not significant). Accuracy was higher with volume-rendered MR cholangiography (84%) than with thick-section and maximum-intensity-projection MR cholangiography (79% for both, not significant). Observer performance with volume-rendered MR cholangiography (A(z) = 0.791--0.952) was better than that with thick-section (A(z) = 0.722--0.834) and maximum-intensity-projection MR cholangiography (A(z) = 0.771--0.887). Image quality was better with maximum-intensity-projection MR cholangiography and thick-section MR cholangiography than with volume-rendered MR cholangiography (p < 0.0001). CONCLUSION: Observer performance with volume-rendered MR cholangiography was better than that with maximum-intensity-projection and thick-section MR cholangiography for the diagnosis of choledocholithiasis. Volume rendering may be an efficient technique for the reconstruction of MR cholangiography.

Adult↗

PubMed2001

Detection of malignant hepatic tumors: comparison of gadolinium-and ferumoxide-enhanced MR imaging.

OBJECTIVE: The purpose of our study was to compare how well gadolinium-enhanced and ferumoxide-enhanced MR imaging reveal malignant hepatic tumors. SUBJECTS AND METHODS: Both gadolinium-enhanced and ferumoxide-enhanced MR imaging were separately performed in 53 patients with a total of 87 malignant hepatic tumors (57 hepatocellular carcinomas, 28 metastases, two cholangiocarcinomas). Thirty-one of the 53 patients had hepatic cirrhosis. Images were reviewed by three independent off-site observers. Observer performance was evaluated by means of sensitivity, specificity, and receiver operating characteristic curve analyses. RESULTS: Gadolinium-enhanced MR imaging outperformed ferumoxide-enhanced MR imaging in sensitivity (81% versus 62%, p < 0.01) for malignant-tumor detection. Specificity was comparable (94%) between the two types of MR imaging. Area under receiver operating characteristic curve (A(z)) value was significantly higher with gadolinium-enhanced MR imaging than with ferumoxide-enhanced MR imaging in patients overall (A(z) = 0.896 versus 0.805, p < 0.001), in patients with cirrhosis (A(z) = 0.907 versus 0.807, p < 0.001), and in patients without cirrhosis (A(z) = 0.899 versus 0.834, p < 0.01). The superiority was enhanced in the subset of patients with cirrhosis. CONCLUSION: Gadolinium-enhanced MR imaging outperforms ferumoxide-enhanced MR imaging in revealing malignant hepatic tumors. Gadolinium-enhanced MR imaging is recommended, particularly for patients with cirrhosis.

Aged↗

PubMed2001

[Current practice in MR imaging of the liver].

MR imaging, which is able to evaluate T1- and T2-relaxation time, fat, hemorrhage, metal deposition, blood flow, perfusion, diffusion, and so on, has offered more information for the diagnosis of diffuse and focal hepatic diseases than CT. The spoiled-GRE sequence with high contrast resolution and ease of the aimed contrast capture derived from the k-space property, with the use of a phased-array multicoil, have remarkably increased the value of gadolinium-enhanced dynamic MR diagnosis of the liver. In recent years, the clinical use of ferumoxide has begun, and issues concerning the superiority or inferiority and combination of contrast media are being debated. This paper describes the value, role, and clinical practice of unenhanced, gadolinium-enhanced, and ferumoxide-enhanced MR imaging of the liver based on knowledge obtained in our institution, with some reference to the literature.

Carcinoma, Hepatocellular↗

PubMed2000

Determination and bioimaging method for nitric oxide in biological specimens by diaminofluorescein fluorometry.

A simple and sensitive assay and a cellular bioimaging method for nitric oxide (NO) were developed using a novel diaminofluorescein DAF-FM and its diacetate. DAF-FM is converted via an NO-specific mechanism to an intensely fluorescent triazole derivative. For the measurement of NO, the triazole derivative of DAF-FM was determined by reversed-phase high-performance liquid chromatography with fluorescence detection. In the presence of 1 microM DAF-FM, the concentrations of NOR-1, an NO donor, in the range of 2-200 nM were linearly related to the fluorescence intensity. This sensitive NO assay enabled us to detect the spontaneous and substance P-induced NO release from isolated porcine coronary arteries, both of which were dependent entirely on the NO synthase activity in vascular endothelial cells. We also obtained fluorescence images of cultured smooth muscle cells of the rat urinary bladder after loading with DAF-FM diacetate. In the cells pretreated with cytokines, the fluorescence intensity increased with time after DAF-FM loading. This increase in the fluorescence intensity was blocked by prior treatment of the muscle cells with an NO synthase inhibitor, N(G)-nitro-l-arginine methyl ester. Therefore, the present novel diaminofluorescein fluorometry should be useful not only for sensitive NO assay, but also for NO imaging in a variety of biological specimens.

Animals↗

PubMed2000

Author reply

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Journal Article↗

PubMed2000

Effects of cyclic polylactate (CPL) on the growth of cloned leukemic cells in vitro.

A novel supramolecular oligomer, cyclic polylactate (CPL), was first discovered in the culture medium of HeLa-S tumour cells, and was reported to inhibit the growth of FM3A ascites tumour cells by inhibiting the activities of pyruvate kinase (PK) and lactic dehydrogenase (LDH). We have now synthesized CPL-containing oligomers with polymerization numbers ranging from 9 to 19, by prolonged heating and rapid mixing of a carbohydrate compound of the L-lactic acid monomer (C(3)H(6)O(3)) under decreased pressure and have studied its effects on the growth of leukemic cells. Treatment with 0.02 mg/ml CPL inhibited the growth of HL60 and TF-1 cells, while the growth of K562 cells was inhibited by 0.2 mg/ml CPL. A concentration of 2 mg/ml CPL was required to inhibit granulocyte-macrophage progenitor cell (CFU-GM) and burst-forming unit erythroid (BFU-E) precursor colony formation among normal bone marrow cells. Furthermore, 7A6 antigen expression and DNA ladder formation were observed in leukemic cells cultured with CPL, indicating that CPL induces apoptotic changes in these cells. These findings suggest that CPL might be a useful chemotherapeutic agent for leukemia.

Antineoplastic Agents↗

PubMed2000

T2-weighted MR imaging for focal hepatic lesion detection: supplementary value of breath-hold imaging with half-Fourier single-shot fast spin-echo and multishot spin-echo echoplanar sequences.

The purpose of our study was to evaluate the supplementary value of breath-hold fat-suppressed T2-weighted magnetic resonance (MR) imaging with half-Fourier single-shot fast spin-echo (SE) or multishot SE echoplanar (EP) sequences combined with respiratory-triggered fat-suppressed fast SE T2-weighted MR imaging for detection and characterization of focal hepatic lesions. MR images in 42 patients with 82 solid, malignant and 77 nonsolid, benign lesions were analyzed. Image review was conducted on a segment-by-segment basis; in all, 333 liver segments were reviewed separately for solid and nonsolid lesions by three independent radiologists. For solid lesions, observer performance with receiver-operating-characteristic (ROC) analysis in one radiologist and specificity in another significantly improved after adding single-shot fast SE images. For nonsolid lesions, observer performance with ROC analysis in one radiologist and specificity in another significantly improved after adding single-shot fast SE images. Combining breath-hold half-Fourier single-shot fast SE imaging with respiratory-triggered fast SE imaging may be recommended for improved detection and characterization of focal hepatic lesions. J. Magn. Reson. Imaging 2000;12:444-452.

Adipose Tissue↗

PubMed2000

Pseudothrombosis in the portal venous system: a potential pitfall with gadolinium-enhanced dynamic gradient-recalled echo imaging of the liver.

Gadolinium-enhanced dynamic magnetic resonance (MR) images in 90 patients were reviewed to assess the artifacts mimicking portal venous thrombosis. The incidence of definite signal-intensity decrease mimicking pathologic condition was higher (P < 0.01) in the right (8%) and left (9%) portal vein branches and portal trunk (6%) than in the splenic (0%) or superior mesenteric (1%) vein with equilibrium-phase images. Radiologists should remember that dynamic MR images occasionally show signal-intensity decrease mimicking portal venous thrombosis due to flow artifact.

Adult↗

PubMed2000

Mid-term follow up results of Japanese heart transplant patients operated in UCLA Medical Center.

UNLABELLED: Japanese candidates have been accepted for heart transplantation by the UCLA Medical Center in the US since 1993 due to the lack of donors available from brain-dead patients. OBJECTIVES AND METHODS: We monitored to patients who underwent such heart transplantation and have been seen at the out-patient clinic at Tokyo Women's Medical University following transplantation. Pre-operative diagnosis was dilated cardiomyopathy in all patients. One patient underwent Novacor implantation as a bridge to heart transplant. All patients underwent cardiac echocardiography and cardiac catheterization including intraluminal echography. RESULTS: All patients survived with an actuarial survival curve of 100% at 1 year, 100% at 3 years and 87% at 5 years in 4.15 years of average follow-up. Two patients died due to liver dysfunction and cerebral emboli. The postoperative functional status of patients was New York Heart Association classification I in 8 (100%). Immunosuppressive therapies included triple drug therapy using either cyclosporin or tacrolimus. The incidence of acute rejection (/pt) exceeding grade 3 was 4% within three months, 3.5% in 3-6 months, and no significant rejection episode more than 6 months after transplantation. Posttransplantation coronary artery disease was seen in 2 patients, but no progression was seen after diltiazem therapy. CONCLUSION: Our postoperative follow-up after cardiac transplantation appears to be satisfactory.

Adult↗

PubMed2000

Establishment of stromal cell line from an MDS RA patient which induced an apoptotic change in hematopoietic and leukemic cells in vitro.

OBJECTIVE: We previously reported on the heterogeneity of bone marrow stromal cell function in supporting hematopoietic cell proliferation and differentiation in vitro among refractory anemia (RA) of myelodysplastic syndrome (MDS) patients. Interestingly, stromal cells from some MDS RA patients induced an apoptotic change in CD34+ hematopoietic cells. However, the mechanism responsible for this action was unclear. MATERIALS AND METHODS: In the present study, we established a cloned stromal cell line (LS801) from an MDS RA patient by introducing recombinant SV40-adenovirus vector containing the SV40 early gene. RESULTS: LS801 induced an apoptotic change in CD34+ cells from normal subjects and cloned leukemic cells in a coculture system. When hematopoietic cells were cocultured but kept separate from LS801 by a 0.45-microm Millipore membrane to prevent their attachment, the action of LS801 in inducing apoptosis of hematopoietic cells was inhibited. Additionally, no production of fas ligand, tumor necrosis factor alpha or interferon gamma in LS801 was observed. CONCLUSION: These findings suggest that the novel stromal cell line LS801 will shed light on research into the mechanism underlying the apoptotic changes induced by stromal cells in hematopoietic cells.

Anemia, Refractory↗

PubMed2000

Magnetic resonance spectroscopy of tubers in patients with tuberous sclerosis.

OBJECTIVE: The histological features of cortical tubers in patients with tuberous sclerosis (TS) were studied by the proton magnetic resonance spectroscopy (MRS). MATERIAL AND METHODS: The subjects were 4 children, mean age of 10 years, with clear evidence of tubers on MRI and SPECT. Four age-matched control children served as control subjects. Spectra were acquired over the tuber using short TE. RESULTS: The myoinositol/creatine ratios in the tubers of TS patients were significantly increased compared with those of the control subjects (P < 0.02). The NAA/creatine ratios in the tubers of patients were significantly decreased (P < 0.02). CONCLUSIONS: The decrease of NAA/creatine ratios in the tubers of patients was considered to reflect a reduction of cranial neurons. The increase of myoinositol/creatine ratios in the tubers was thought to reflect an increase of glial cells. Proton MRS might play a role in estimation of histological changes in the neurological diseases.

Adult↗

PubMed2000

Mouse oviduct-specific glycoprotein gene: genomic organization and structure of the 5'-flanking regulatory region.

A member of the chitinase protein family, oviduct-specific glycoprotein (OGP), can directly associate with gametes or with the early embryo in the oviduct. Although the glycoprotein is widely distributed among mammalian species and there is indirect evidence concerning the involvement of the molecule in the fertilization process, its physiological functions are far from completely understood. To understand the fundamental mechanisms that direct gene expression as well as to know the physiological significance of OGP, we have isolated and characterized a mouse OGP gene (mogp-1). The gene was found to span 13.4 kilobases (kb) including 11 exons and 10 introns. The genomic organization of mogp-1 is well conserved compared to the other members of the chitinase family. Two transcription initiation sites were found at positions 18 and 14 upstream from the first ATG codon. Fluorescence in situ hybridization analysis demonstrated that the mogp-1 was located on the R-positive F3 band of mouse chromosome 3. Although the putative promoter region of mogp-1 lacked typical TATA, CAAT, or GC box sequences, the region contained several motif sequences of transcription factor binding sites including 10 half-palindromic estrogen responsive elements (ERE) and an imperfect ERE. Transient transfection experiments demonstrated that promoter activity could be modulated by various sequences within the 2.2 kb of the 5'-flanking region, and that the mogp-1 promoter was transactivated in an estrogen receptor-positive cell line, MCF-7, by the addition of estradiol-17beta (E(2)). In addition, relevant promoter activity for E(2) responsiveness resides within the first 270 base pairs upstream of the mogp-1. These findings should facilitate our understanding of the regulation of OGP gene expression, and they may be helpful for designing experiments to unravel the role of OGP in the process of mammalian fertilization.

Amino Acid Sequence↗

PubMed2000

Establishment of a porcine cell line from in vitro-produced blastocysts and transfer of the cells into enucleated oocytes.

The present study was conducted to establish a porcine cell line from blastocysts produced in vitro and to examine the developmental ability of nuclear transfer embryos reconstituted with the cells and enucleated mature oocytes. When hatched blastocysts were cultured in Dulbecco's modified Eagle's medium with supplements, no colonies of embryo-derived cells were observed. In contrast, 56% of embryos that were attached to feeder layers of STO cells formed colonies in NCSU-23 with supplements. When the colonies were subcultured in the absence of feeder cells, a cell line with an epithelial-like cell morphology was obtained. This cell morphology was stable up to at least passage 30. Although no fused embryos were observed when a pulse of 100 V/mm was applied, the fusion rate increased significantly at 150 V/mm (28%) and 200 V/mm (64%). At 200 V/mm, 39% of fused embryos cleaved, but no embryos developed beyond the 3-cell stage. When cocultured with electro-activated oocytes, percentages of reconstructed embryos cleaved (65%) and developed to the 4-cell stage (23%) were significantly higher than percentages for those (cleavage: 38%; 4-cell stage: 3%) in the absence of activated oocytes. At 7 days after culture, one reconstructed embryo successfully developed to the blastocyst stage in the presence of activated oocytes. When green fluorescent protein-expressing cells and enucleated oocytes were fused and the fused embryos were cultured with electro-activated oocytes, 3 of 102 reconstructed embryos developed to the blastocyst stage. All of the blastocysts were positive for fluorescent green under ultraviolet light. The results of the present study indicate that a porcine cell line can be established from the hatched blastocyst and maintained in vitro for a long period, and that reconstructed embryos obtained by transferring the blastocyst-derived cells into enucleated oocytes have the ability to develop to the blastocyst stage in vitro.

Animals↗

PubMed2000

Pancreas and peripancreatic vessels: effect of imaging delay on gadolinium enhancement at dynamic gradient-recalled-echo MR imaging.

PURPOSE: To investigate the effect of imaging delay on gadolinium enhancement of the pancreas and peripancreatic vessels at dynamic gradient-recalled-echo magnetic resonance (MR) imaging of the pancreas. MATERIALS AND METHODS: Dynamic MR images were obtained after intravenous bolus injection of gadopentetate dimeglumine in 75 patients with no pancreatic malignancies. Test-bolus imaging was performed to determine aortic transit time in individual patients. Patients were randomly assigned so that the middle of k space was acquired at 5, 15, 25, 35, or 45 seconds after arrival of contrast material in the abdominal aorta. Mean signal intensities of pancreas, liver, and peripancreatic vessels were measured, and images were qualitatively assessed by two radiologists. RESULTS: The best pancreatic enhancement occurred at a delay of 15 seconds (P <.05). The best enhancement of the liver and peripancreatic vessels occurred at 25 seconds or later (P <.05). Qualitatively, the best images of the pancreas were obtained at 15 seconds, and the best images of the liver and peripancreatic vessels were obtained at 25 seconds or later. CONCLUSION: Biphasic imaging at 15 and 45 seconds or later after arrival of contrast material in the abdominal aorta is a practical method for acquisition of high-quality dynamic gradient-recalled-echo MR images of the pancreas.

Adult↗

PubMed2000

Efficient isolation and long-term viability of bovine small preantral follicles in vitro.

A comparison of isolation techniques for small preantral follicles (30-70 microm) from bovine ovaries using a mechanical method with a grating device or collagenase treatment was performed. The mean number (157.0) of intact follicles per ovary isolated by the mechanical method was significantly greater (P < 0.05) than that (26.0) of follicles isolated by the enzymatic method. Isolated morphologically normal follicles (MNF) were cultured for up to 30 d either in control cultures (non-coculture) or in coculture with bovine ovary mesenchymal cells (BOM), fetal bovine skin fibroblasts (FBF), and/or bovine granulosa cells (BGC). In control cultures, most of the follicles degenerated and only a few MNF (1.2%) were present after 30 d in culture. In contrast, the cocultures with BOM, FBF, and BGC resulted in 50.7, 46.6, and 21.4% viable MNF, respectively. Trypan blue and Hoechst 33258 staining were used for a quick and sensitive assessment of oocyte and granulosa cell viability during follicle isolation and culture in vitro. After 30 d, percentages of viable follicles in coculture with BOM (18.6%) and FBF (17.1%) were significantly greater than those of follicles in the control cultures (0%) or in coculture with BGC (10.0%). There was a gradual increase in the average diameter of the MNF during culture. The mean diameter of the follicles increased by 15.4 and 30.0% in coculture with BOM and FBF, respectively, by day 30. In conclusion, small bovine preantral follicles were efficiently isolated using a mechanical method that utilizes a grating device, and could be maintained for up to 30 d in the presence of mesenchymal cell cocultures such as BOM and FBF. This in vitro culture system that supports long-term survival of bovine preantral follicles should be beneficial for studying follicle growth and development.

Animals↗

PubMed2000

Preoperative detection of malignant hepatic tumors: comparison of combined methods of MR imaging with combined methods of CT.

OBJECTIVE: We compared radiologists' performance on combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR imaging with their performance on helical CT during arterial portography (CTAP) and biphasic CT during hepatic arteriography (CTHA) for the preoperative detection of malignant hepatic tumors. SUBJECTS AND METHODS: MR images and CT scans obtained in 33 patients were retrospectively analyzed. Images of the liver were reviewed on a segment-by-segment basis; a total of 261 segments with 39 hepatocellular carcinomas and 21 metastases were independently reviewed by three radiologists who were invited from outside institutions. Unenhanced and gadolinium-enhanced MR images were reviewed first, then ferumoxides-enhanced MR images were added for combined review. CTAP images and biphasic CTHA images were reviewed together. RESULTS: Sensitivity for the detection of hepatic tumors was analogous for combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR images (86%) and for combined CTAP images and biphasic CTHA images (87%). Specificity was higher with MR images (95%, p < 0.01) than with CT images (91%). Radiologists' performances were improved (Az = 0.962, p = 0.0502) by combining ferumoxides-enhanced MR images with unenhanced and gadolinium-enhanced MR images (Az = 0.950), and were analogous for combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR images and for combined CTAP images and biphasic CTHA images (Az = 0.959). CONCLUSION: Radiologists' performances on combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR imaging compared with their performances on combined helical CTAP and biphasic CTHA are analogous for the preoperative detection of malignant hepatic tumors. Such a dedicated combination of MR imaging may obviate the need for more invasive angiographically assisted helical CT for the preoperative detection of malignant hepatic tumors.

Aged↗

PubMed2000

Revealing hepatic metastases from colorectal cancer: value of combined helical CT during arterial portography and CT hepatic arteriography with a unified CT and angiography system.

OBJECTIVE: The purpose of our study was to evaluate the use of combined helical CT during arterial portography and CT hepatic arteriography in the preoperative assessment of hepatic metastases from colorectal cancer using a unified CT and angiography system. MATERIALS AND METHODS: Fifty-four patients with hepatic metastases from colorectal cancer preoperatively underwent combined CT during arterial portography and CT hepatic arteriography using the unified CT and angiography system. Three radiologists independently and retrospectively reviewed the images of CT during arterial portography alone, CT hepatic arteriography alone, and combined CT during arterial portography and CT hepatic arteriography. Image review was conducted on a segment-by-segment basis; a total of 432 hepatic segments with (n = 103) 118 metastatic tumors ranging in size from 2 to 160 mm (mean, 25.8 mm) and without (n = 329) tumor were reviewed. RESULTS: Relative sensitivity of combined CT during arterial portography and CT hepatic arteriography (87%) was higher than that of CT during arterial portography alone (80%, p < 0.0005) and CT hepatic arteriography alone (83%, p < 0.005). Relative specificity of CT hepatic arteriography alone (95%, p < 0.0005) and combined CT during arterial portography and CT hepatic arteriography (96%, p < 0.0001) was higher than that of CT during arterial portography alone (91%). Diagnostic accuracy, determined by a receiver operating characteristic curve analysis, was greater with combined CT during arterial portography and CT hepatic arteriography than with CT during arterial portography alone (p < 0.05) or CT hepatic arteriography alone (p < 0.01). CONCLUSION: Using a unified CT and angiography system, we found that combined CT during arterial portography and CT hepatic arteriography significantly raised the detectability of hepatic metastases from colorectal cancer.

Adult↗

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↗