Biomedical subjects

Hiroshi Kondo

Publications and source records attributed to Hiroshi Kondo.

At least 19 recordsLinked to original sources

PubMed2005

Sacsin-related autosomal recessive ataxia without prominent retinal myelinated fibers in Japan.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) has been described in the Quebec region and in Tunisia. We report on two Japanese siblings with a new homozygous mutation (6543 del A) of the SACS gene. Compared with previously reported ARSACS patients, both of these patients had a unique phenotype characterized by dementia, ophthalmoplegia, and the absence of prominent retinal myelinated fibers.

Ataxia↗

PubMed2005

Solitary mediastinal lymph node metastasis of hepatocellular carcinoma: MR imaging findings.

A 65-year-old man with multiple hepatocellular carcinomas in the liver with type C viral hepatitis had a solitary mediastinal lymph node metastasis in the right paratracheal to tracheobronchial region. Surgical resection for the mediastinal metastasis was undertaken based on magnetic resonance (MR) imaging findings, suggesting its radicality. We assess the MR imaging findings and presumable pathways of lymphatic metastasis from the liver to mediastinal lymph nodes in this report.

Aged↗

PubMed2005

Does T2-weighted MR imaging improve preoperative detection of malignant hepatic tumors? Observer performance study in 49 surgically proven cases.

The purpose of our study was to determine whether or not the addition of T2-weighted fast spin-echo (SE) imaging to gadolinium-enhanced spoiled gradient-recalled-echo (GRE) imaging improves the observer performance in the preoperative detection of malignant hepatic tumors. Gadolinium-enhanced GRE and fat-suppressed T2-weighted fast SE images obtained in 49 patients with 82 surgically confirmed malignant hepatic tumors (40 hepatocellular carcinomas and 42 metastases) were retrospectively reviewed by three independent off-site observers. In the random review of images, gadolinium-enhanced GRE images were reviewed first; thereafter, T2-weighted fast SE images were added for combined review. Observer performance was evaluated with the McNemar's test and receiver operating characteristic curve analysis. For gadolinium-enhanced GRE images alone vs. combined images, sensitivities for detection were 78% vs. 79% for hepatocellular carcinomas (P>.05), 67% vs. 71% for metastases (P<.05) and 72% vs. 75% for tumors overall (P<.05), respectively. The Az values were 0.892 vs. 0.889 in hepatocellular carcinomas (P>.05), 0.797 vs. 0.828 in metastases (P<.05) and 0.839 vs. 0.846 in tumors overall (P>.05), respectively. Our results showed that the addition of T2-weighted fast SE imaging to gadolinium-enhanced GRE imaging improved the observer performance in the detection of metastases.

Adult↗

PubMed2005

Expression of vascular endothelial growth factor in hepatocellular carcinoma and the surrounding liver and correlation with MRI findings.

OBJECTIVE: The purpose of our study was to assess the correlation between the quantitative and qualitative imaging findings on unenhanced and gadolinium-enhanced MR images and the intensity of vascular endothelial growth factor (VEGF) expression in hepatocellular carcinomas and in the surrounding nontumorous liver. MATERIALS AND METHODS: The intensities of VEGF expression in hepatocellular carcinoma and in the surrounding liver by Western blot analysis were converted to VEGF expression indexes (VEGF(IND)) in 22 surgical specimens ranging in size from 14 to 126 mm (mean, 47.6 +/- 29.5 mm) that were resected in 22 patients (17 men and five women; age range, 41-85 years [mean, 64 years]) between April 2000 and October 2002. MR images were retrospectively evaluated to determine contrast-to-noise ratios (CNRs), signal intensity SD ratios, and phase-shift indexes. Signal intensity characteristics of hepatocellular carcinomas were reviewed independently by two experienced radiologists who were unaware of the pathologic diagnosis or the results of immunoblotting. CNRs, SD ratios, and phase-shift indexes were correlated with VEGF(IND) using a simple regression test, and signal intensity characteristics were correlated with VEGF(IND) using the Spearman's rank correlation test. RESULTS: On opposed-phase T1-weighted spoiled gradient-recalled echo (GRE) images, CNRs correlated inversely with the VEGF(IND) of hepatocellular carcinomas (r = -0.46, p = 0.038). CNRs on T2-weighted fast spin-echo images correlated directly with the VEGF(IND) of hepatocellular carcinomas (r = 0.49, p = 0.025), and on gadolinium-enhanced hepatic arterial phase GRE images marginally and inversely correlated with VEGF(IND) (r = -0.39, p = 0.081). On T2-weighted fast spin-echo images, SD ratios correlated directly with the VEGF(IND) of hepatocellular carcinomas (r = 0.44, p = 0.044). No correlation was found between phase-shift indexes and VEGF expression. The qualitatively assessed signal intensity heterogeneities of hepatocellular carcinomas correlated directly with the VEGF(IND) of hepatocellular carcinomas on opposed-phase T1-weighted GRE, T2-weighted fast spin-echo, hepatic arterial phase GRE, and equilibrium phase GRE images. CONCLUSION: Our results indicate that the signal intensity and heterogeneity of hepatocellular carcinomas on MR images correlate with the degree of VEGF expression in hepatocellular carcinomas.

Adult↗

PubMed2004

Ferumoxide-enhanced MR imaging of hepatocellular carcinoma: correlation with histologic tumor grade and tumor vascularity.

PURPOSE: To evaluate ferumoxide-enhanced MR imaging findings of hepatocellular carcinomas (HCCs) in correlation with the histologic tumor grades and the tumor vascularity evaluated by CT hepatic arteriography (CTHA) and CT during arterial portography (CTAP) combined. MATERIALS AND METHODS: By searching the radiologic, surgical, and pathologic reports of our institution between January 1999 and February 2001, we identified 43 patients with 51 pathologically confirmed HCCs who underwent ferumoxide-enhanced MR imaging and combination CTHA and CTAP within two weeks. The HCCs consisted of 17 well-differentiated, 28 moderately differentiated, and six poorly differentiated tumors. The MR and CT were retrospectively reviewed by two radiologists in consensus for signal intensity on MR images and vascularity on CT. The Spearman's rank correlation coefficient was calculated to correlate the frequency of tumors with ferumoxide uptake with the histologic tumor grades and the tumor vascularity on CTHA and CTAP. RESULTS: A total of 45 tumors (88%) did not take up ferumoxide, and thus showed distinct, homogeneous hyperintensity. Six tumors (12%) ranging 5-16 mm in size (mean, 11 mm) took up ferumoxide, and thus showed isointensity, mixed intensity, or hypointensity, including five of 17 (29%) well-differentiated tumors and one of 28 (4%) moderately differentiated tumors. Five of the six tumors (83%) showed hyper- or hypovascularity on CTHA or hypovascularity on CTAP. The frequency of tumors with ferumoxide uptake showed weak correlation with tumor grades (coefficient = 0.26, P < 0.01) and vascularity on CTHA (-0.35, P < 0.05) and CTAP (0.39, P < 0.01). CONCLUSION: Although a small number of well-differentiated HCC take up ferumoxide and show iso-, mixed, or hypointensity, most such tumors show increased hepatic arterial or decreased portal venous perfusion. The present results suggest the limitation of reticuloendothelial contrast imaging, particularly in the diagnosis of small, well-differentiated HCC.

Aged↗

PubMed2004

Pheochromocytoma with posthemorrhagic cystic degeneration: magnetic resonance imaging findings.

We describe in vivo and in vitro magnetic resonance imaging (MRI) findings of a pheochromocytoma with posthemorrhagic cystic degeneration in a 74-year-old man. The in vivo MR images showed the mass as an area of homogeneous moderate hyperintensity with a central area of intense hyperintensity outlined by a thin hypointense rim on a T2-weighted image. The in vitro MR images showed a hyperintense rim around the central cystic area consistent with hemorrhage on T1-weighted gradient-echo images with short echo times (1.6 and 4.2 msec) and more distinctly revealed the blurring effect due to susceptibility of hemosiderin on those with long echo times (6 and 8 msec). Hemosiderin deposition caused by intraparenchymal hemorrhage in the pheochromocytoma can be appreciated on spoiled gradient-echo images with different echo times, which is ordinarily included in the MRI protocol as phase-shift imaging.

Adrenal Gland Neoplasms↗

PubMed2004

Early-enhancing nonneoplastic lesions on gadolinium-enhanced magnetic resonance imaging of the liver following partial hepatectomy.

PURPOSE: To assess the frequency, imaging findings, and significance of early-enhancing nonneoplastic (EN) lesions with gadolinium-enhanced magnetic resonance imaging (MRI) of the liver following partial hepatectomy. MATERIALS AND METHODS: We retrospectively reviewed MR images after partial hepatectomy in 30 patients. Postoperative MRI was performed in 1-12 months (mean, 3.7 months) after partial hepatectomy. We defined the EN lesion as a lesion that was ill defined; irregular, wedge shaped, or serpiginous; located along the liver edge; not visible on unenhanced MR images; did not appear hypointense on portal venous- or equilibrium-phase images; or a combination of those imaging findings. RESULTS: A total of 39 EN lesions (size range, 5-60 mm; mean, 25.2 mm) in 19 patients and 17 recurrent tumors (size range, 5-50 mm; mean, 16.8 mm) in 10 patients newly appeared after partial hepatectomy. The EN lesions were diagnosed as pseudolesions by the second postoperative follow-up MRI in 17 patients or contrast-enhanced computed tomography (CT) in two. A total of 13 EN lesions (33%) were located along the liver edge and 20 (51%) were adjacent to the resected area. The shape was circular in 11 (28%), oval in three (8%), irregular in 11 (28%), wedge shaped in five (13%), and serpiginous in nine (23%). No EN lesion showed hypointensity on gadolinium-enhanced portal venous-phase or equilibrium-phase images. A total of 14 EN lesions (36%) showed slight hyperintensity on T2-weighted images. The confidence levels for malignancy probability assigned by blinded radiologists were lower with EN lesions than with recurrent tumors (P < 0.001). CONCLUSION: EN lesions are frequently seen in MRI following partial hepatectomy, and occasionally are slightly hyperintense on T2-weighted images, mimicking malignant tumors. However, most EN lesions can be correctly diagnosed with MRI findings.

Aged↗

PubMed2004

Malignant hepatic tumor detection with ferumoxide-enhanced magnetic resonance imaging: is chemical-shift-selective fat suppression necessary for fast spin-echo sequence?

PURPOSE: To determine whether chemical-shift-selective (CSS) fat suppression is necessary for ferumoxide-enhanced T2-weighted fast spin-echo (FSE) imaging in the detection of malignant hepatic tumors. MATERIALS AND METHODS: Ferumoxide-enhanced magnetic resonance (MR) images obtained in 38 patients with surgically confirmed 61 malignant hepatic tumors (36 hepatocellular carcinomas (HCCs), 25 metastases) were retrospectively reviewed by three independent readers. Three sequences of MR images with CSS fat-suppressed T2-weighted FSE, non-fat-suppressed T2-weighted FSE, and T2*-weighted gradient-recalled-echo (GRE) sequences were randomly reviewed on a segment-by-segment basis in a blind fashion. Observer performance was tested using the McNemar's test and receiver-operating-characteristic (ROC) analysis for the clustered data. Lesion-to-liver contrast-to-noise ratio (C/N) was also assessed. RESULTS: The mean C/N with the CSS fat-suppressed FSE sequence was highest in HCCs, metastases, and tumors overall. Sensitivity was highest with the CSS fat-suppressed FSE sequence in HCC, was highest with the non-fat-suppressed FSE sequence in metastases, and was comparable in tumors overall. Specificity was comparable between the sequences. The area under ROC curve (Az) value was greatest with the CSS fat-suppressed FSE sequence in HCCs, was greatest with the non-fat- suppressed FSE sequence in metastases, and was comparable in tumors overall. The sensitivities and Az values were lower with the GRE sequence than the FSE sequence. CONCLUSION: The CSS fat-suppressed FSE sequence was superior to the GRE sequence in the detection of HCCs, but the non-fat-suppressed FSE sequence was comparable to the GRE sequence. The non-fat-suppressed FSE sequence was superior to the CSS fat-suppressed FSE and GRE sequences in the detection of metastases. Optimal FSE imaging with CSS fat suppression or without aiming for the detection of HCCs or metastases, respectively, outperforms GRE imaging in ferumoxide-enhanced MRI.

Aged↗

PubMed2004

Nodule-in-nodule appearance of hepatocellular carcinomas: comparison of gadolinium-enhanced and ferumoxides-enhanced magnetic resonance imaging.

PURPOSE: To perform comparison of gadolinium-enhanced and ferumoxides-enhanced magnetic resonance imaging (MRI) in the detection of nodule-in-nodule appearance of hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: During a recent 45-month period, we had eight patients (five men and three women; age range, 63-84 years; mean, 71 years) with HCCs with nodule-in-nodule appearance who underwent gadolinium-enhanced MRI, ferumoxides-enhanced MRI, and computed tomography during arterial portography (CTAP) and computed tomography during hepatic arteriography (CTHA), combined and separately, within an interval of two weeks. Two blinded radiologists in consensus retrospectively evaluated three sets of sequences: unenhanced T1- and T2-weighted MR, gadolinium-enhanced MR, and ferumoxides-enhanced MR images in random order of patients and imaging sequences. The depiction degree of nodule-in-nodule appearance of HCC was evaluated in a semiquantitative fashion. The sensitivities of unenhanced T1- and T2-weighted, gadolinium-enhanced, and ferumoxides-enhanced MR images were compared with McNemar's test. RESULTS: The eight HCCs with nodule-in-nodule appearance ranged in size from 16-26 mm (mean, 20.0 +/- 4.0 mm), and there existed nine internal HCC foci ranging in size from 5-14 mm (mean, 7.9 +/- 3.5 mm). On gadolinium-enhanced MR images, the nodule-in-nodule appearance of HCC was typically seen as hypervascular foci in an iso- or hypovascular area: the depiction degree of nodule-in-nodule appearance was distinct in two lesions, equivocal in three, and absent in three. On ferumoxides-enhanced MR images, it was typically seen as hyperintense foci in a hypointense area: the depiction degree was distinct in four, moderate in one, and absent in three. The sensitivities for detection of nodule-in-nodule appearance were 25%, 25%, and 63% on T1- and T2-weighted, gadolinium-enhanced, and ferumoxides-enhanced MR images, respectively, but there was no significant difference in sensitivity. CONCLUSION: Nodule-in-nodule appearance of HCCs can be seen on ferumoxides-enhanced MR images, in some cases more clearly than on gadolinium-enhanced MR images, particularly when the background nodule shows hyperintensity on precontrast T1-weighted images. Ferumoxides-enhanced MRI may be considered when development of malignant foci is suspected during routine examinations.

Aged↗

PubMed2004

Inflammatory pseudotumor of the liver: ferumoxide-enhanced MR imaging as a tiebreaker.

We examined a 70-year-old male patient with an inflammatory pseudotumor of the liver mimicking a peripheral-type cholangiocellular carcinoma. Ferumoxide-enhanced magnetic resonance (MR) imaging revealed residual Kupffer cell function in liver parenchyma in and surrounding the inflammatory pseudotumor involvement, which suggested the diagnosis of inflammatory pseudotumor of the liver. We correlate the MR imaging and pathologic findings in this report.

Aged↗

PubMed2004

Detection of malignant hepatic tumors with ferumoxide-enhanced MR imaging: usefulness of multishot and single-shot fast spin echo sequences.

The purpose of our study was to assess whether respiratory-triggered multishot fast spin echo (MS-FSE) and breath-hold half-Fourier single-shot fast spin echo (SS-FSE) images, in addition to breath-hold T(2)*-weighted gradient recalled echo (GRE) images, increase observer performance in the detection of malignant hepatic tumors with ferumoxide-enhanced magnetic resonance (MR) imaging. Ferumoxide-enhanced MR images obtained from 48 patients with 83 malignant hepatic tumors were retrospectively reviewed by three independent off-site readers. In the first image review, GRE images alone were reviewed. Then, MS-FSE images were added for the first combination review. Finally, SS-FSE images were added for the second combination review. Observer performances were tested by McNemar's test and receiver-operating-characteristic analysis for the clustered data. Sensitivity for hepatocellular carcinomas, metastases, and malignant hepatic tumors overall was significantly (p < 0.05) higher with GRE and MS-FSE combined and GRE, MS-FSE and SS-FSE combined than with GRE alone. For metastases, the Az value was significantly (p < 0.05) higher with GRE and MS-FSE combined, and GRE, MS-FSE and SS-FSE combined than with GRE alone. We confirmed the incremental value of ferumoxide-enhanced MR imaging by obtaining MS-FSE and SS-FSE images in addition to GRE images in the detection of malignant hepatic tumors.

Aged↗

PubMed2004

Effects of anticancer chemotherapeutic drugs on the acetylcholine receptor-operated potassium current in guinea pig atrial myocytes.

The effects of 7 anticancer chemotherapeutic drugs on the muscarinic acetylcholine receptor-operated potassium current (I(K.ACh)) in guinea pig atrial myocytes were investigated using the whole cell patch clamp technique. Doxorubicin, pirarubicin, and mitoxantrone inhibited the carbachol-induced I(K.ACh) in a concentration-dependent manner in atrial cells at a holding potential of -40 mV. IC50 values of doxorubicin, pirarubicin, and mitoxantrone for the carbachol-induced I(K.ACh) were 7.7 microM, 3.7 microM, and 9.1 microM, respectively. Pirarubicin inhibited the adenosine-induced and the GTPgammaS-induced I(K.ACh) in a concentration-dependent manner (IC50=6.0 and 5.1 microM, respectively). Doxorubicin and mitoxantrone up to 100 microM did not have an influence on the adenosine-induced I(K.ACh). Doxorubicin did not affect the GTPgammaS-induced I(K.ACh). Mitoxantrone 100 microM inhibited the current only by 25%. For concentrations up to 100 microM, anticancer drugs that have chemical structures entirely different from that of doxorubicin, i.e., 5-fluorouracil, 6-mercaptopurine, cyclophosphamide, and actinomycin D, did not have an influence on the carbachol-induced I(K.ACh). Doxorubicin and chemically related compounds possess anticholinergic effects mediated via an inhibitory action on I(K.ACh) by different underlying molecular mechanisms. Doxorubicin and mitoxantrone may inhibit I(K.ACh) by the blockade of muscarinic receptors, whereas pirarubicin may inhibit the current not only via blocking the muscarinic receptors but also by depressing the functions of the K+ channel itself and/or GTP-binding proteins.

Animals↗

PubMed2004

Detection of malignant hepatic tumors with ferumoxides-enhanced MRI: comparison of five gradient-recalled echo sequences with different TEs.

OBJECTIVE: The purpose of our study was to compare the detectability of malignant hepatic tumors on ferumoxides-enhanced MRI using five gradient-recalled echo sequences at different TEs. MATERIALS AND METHODS: Ferumoxides-enhanced MRIs obtained in 31 patients with 50 malignant hepatic tumors (33 hepatocellular carcinomas, 17 metastases) were reviewed retrospectively by three independent offsite radiologists. T1-weighted gradient-recalled echo images with TEs of 1.4 and 4.2 msec; T2*-weighted gradient-recalled echo images with TEs of 6, 8, and 10 msec; and T2-weighted fast spin-echo images of livers were randomly reviewed on a segment-by-segment basis. Observer performance was tested using the McNemar test and receiver operating characteristic analysis for the clustered data. Lesion-to-liver contrast-to-noise ratio was also assessed. RESULTS: Mean lesion-to-liver contrast-to-noise ratios were negative and lower with gradient-recalled echo at 1.4 msec than with the other sequences. Sensitivity was higher (p < 0.05) with gradient-recalled echo at 6, 8, and 10 msec and fast spin-echo sequences (75-83%) than with gradient-recalled echo sequences at 1.4 and 4.2 msec (46-48%), and was higher (p < 0.05) with gradient-recalled echo sequence at 8 msec (83%) than with gradient-recalled echo at 6 msec and fast spin-echo sequences (75-78%). Specificity was comparably high with all sequences (95-98%). The area under the receiver operating characteristic curve (A(z)) was greater (p < 0.05) with gradient-recalled echo at 6, 8, and 10 msec and fast spin-echo sequences (A(z) = 0.91-0.93) than with gradient-recalled echo sequences at 1.4 and 4.2 msec (A(z) = 0.82-0.85). CONCLUSION: In the detection of malignant hepatic tumors, gradient-recalled echo sequences at 8 msec showed the highest sensitivity and had an A(z) value and lesion-to-liver contrast-to-noise ratio comparable with values from gradient-recalled echo sequences at 6 and 10 msec and fast spin-echo sequences.

Aged↗

PubMed2004

Expression of vascular endothelial growth factor in hepatocellular carcinoma and the surrounding liver: correlation with angiographically assisted CT.

OBJECTIVE: The purpose of our study was to assess the correlation between the intensity and characteristics of contrast enhancement on angiographically assisted CT and the intensity of vascular endothelial growth factor (VEGF) expression in hepatocellular carcinoma (HCC) and in the surrounding nontumorous liver. MATERIALS AND METHODS: The intensity of VEGF expression in HCC and in the surrounding liver was expressed as a VEGF expression index by Western blot analysis in 20 surgical specimens resected in 20 patients between March 2000 and August 2002. Findings on CT during arterial portography (n = 20) and CT hepatic arteriography (n = 17) were retrospectively evaluated to determine contrast enhancement indexes and the enhancement characteristics of HCCs and of the surrounding liver. Contrast enhancement indexes and VEGF expression indexes were correlated using a simple regression test, and enhancement characteristics and VEGF expression indexes were correlated using the Spearman's rank correlation test. RESULTS: On CT hepatic arteriography, the contrast enhancement indexes of HCCs showed moderate inverse correlation with the VEGF expression indexes of HCCs (r = -0.57, p = 0.017) and high inverse correlation with the differences between the VEGF expression indexes of HCCs and those of livers (difference in the VEGF expression index, -0.80; p = 0.0001). The contrast enhancement index of the liver showed marginal moderate direct correlation with the VEGF expression index of the liver (0.44, p = 0.076) and high inverse correlation with the difference in the VEGF expression index (-0.71, p = 0.0013). On CT during arterial portography, the contrast enhancement indexes of HCCs showed moderate inverse correlation with the difference in the VEGF expression index (-0.51, p = 0.023). The qualitative degree of heterogeneity of hepatic artery enhancement in HCC on CT hepatic arteriography showed moderate direct correlation with the VEGF expression indexes of HCCs (0.55, p = 0.033) and high direct correlation with the difference in the VEGF expression indexes (0.73, p = 0.004). CONCLUSION: Our results indicated that the intensity and heterogeneity of hepatic artery enhancement of HCCs on CT hepatic arteriography correlated with the degree of VEGF expression in HCCs.

Adult↗

PubMed2004

Performance evaluation of the complete blood count and white blood cell differential parameters obtained using a Celltac F automated hematology analyzer.

Performance of a new hematology analyzer, the Celltac F, MEK-8222 (Nihon Kohden, Tokyo, Japan), was evaluated. This analyzer simultaneously measures 22 parameters including leukocyte differentials. Within- and between-batch precision, linearity, and absence of carryover were all excellent. Accurate measurements of complete blood count parameters were possible during the 48-hour test periods for stability at 4 degrees C and room temperature. Automated differential parameters showed acceptable stability during the 24-hour test period. The performance was evaluated in comparison with the CD-4000 (Abbott, Abbott Park, IL, USA). There was a good correlation between findings with the Celltac F and those with the CD-4000 hematology analyzer for complete blood count parameters and leukocyte differential parameters other than percentages of basophils. Comparisons of differential leukocyte counts to microscopic differentials were excellent for neutrophils, lymphocytes, and eosinophils and were acceptable for monocytes. The clinical utility and flagging performance were excellent. The Celltac F is compact and it is able to process 80 samples per hour. The volumes of sample and reagent consumed were slight. The instrument has good potential to contribute to effective total cost management and to be a useful backup system with high throughput, while taking up minimal space in the clinical laboratory.

Blood Cell Count↗

PubMed2003

Complete sequencing and characterization of 21,243 full-length human cDNAs.

As a base for human transcriptome and functional genomics, we created the "full-length long Japan" (FLJ) collection of sequenced human cDNAs. We determined the entire sequence of 21,243 selected clones and found that 14,490 cDNAs (10,897 clusters) were unique to the FLJ collection. About half of them (5,416) seemed to be protein-coding. Of those, 1,999 clusters had not been predicted by computational methods. The distribution of GC content of nonpredicted cDNAs had a peak at approximately 58% compared with a peak at approximately 42%for predicted cDNAs. Thus, there seems to be a slight bias against GC-rich transcripts in current gene prediction procedures. The rest of the cDNAs unique to the FLJ collection (5,481) contained no obvious open reading frames (ORFs) and thus are candidate noncoding RNAs. About one-fourth of them (1,378) showed a clear pattern of splicing. The distribution of GC content of noncoding cDNAs was narrow and had a peak at approximately 42%, relatively low compared with that of protein-coding cDNAs.

Chromosomes, Human, 21-22 and Y↗

PubMed2003

Cellular aging-dependent decrease in cholesterol in membrane microdomains of human diploid fibroblasts.

Recently it has been shown that cholesterol plays indispensable roles in the function of cholesterol-rich microdomains (rafts), such as in ligand-mediated signal transduction. Using a perfringolysin O derivative (BCtheta) that binds selectively to cholesterol in rafts without causing membrane damage (Proc. Natl. Acad. Sci. USA 98 (2001) 4926), we have investigated the effect of in vitro replicative aging of human diploid fibroblasts, TIG-1, on the distribution of plasma membrane cholesterol. The amount of BCtheta-labeled membrane cholesterol decreased during replicative aging of TIG-1 cells, whereas total cholesterol increased somewhat. The relationship was confirmed by double staining with BCtheta and senescence-associated-beta-galactosidase, a biomarker of senescent cells. Cell fractionation experiments revealed decreases in both cholesterol in rafts and a raft marker, flotillin, during replicative aging. In addition, hydroxyurea-induced prematurely senescent cells also showed a lower level of BCtheta-labeled cholesterol than untreated cells, despite maintaining the total amount of cholesterol. When TIG-1 cells were cultured in cholesterol-deficient medium, BCtheta labeling was first diminished and then premature senescence was induced. Taken together with the reduced signaling capacity of aged cells, these results suggest that plasma membrane cholesterol in raft microdomains is more sensitive to senescence than total cholesterol and is a primary target in aging.

Apoptosis↗

PubMed2003

Novel transgenic rat for in vivo genotoxicity assays using 6-thioguanine and Spi- selection.

Transgenic rodents are valuable models for investigating the genotoxicity of chemicals in vivo. Here, we report the establishment of a novel transgenic rat for genotoxicity analysis. In this model, about 10 copies of lambdaEG10 DNA carrying the gpt gene of E. coli and the red/gam genes of lambda phage are integrated per haploid genome of Sprague-Dawley rats at position 4q24-q31. After recovery of lambdaEG10 phage, point mutations in the gpt gene and deletions in the red/gam genes are identified by 6-thioguanine and Spi(-) selection, respectively. To examine the suitability of these rats for performing in vivo mutagenicity assays, rats were treated with single intraperitoneal injections of ethylnitrosourea (ENU; 100 mg/kg) or benzo[a]pyrene (B[a]P; 62.5 and 125 mg/kg), and the mutant frequencies (MFs) in the liver were determined 7 days after the treatment. ENU enhanced the gpt MF about 7-fold over the control while it did not significantly increase the Spi(-) MF. B[a]P increased both the gpt and Spi(-) MFs several-fold in a dose-dependent manner. To examine the kinetics of MF, ENU was administered (50 mg/kg/day for 5 successive days) and gpt MFs in the liver were determined 7, 21, 35, and 70 days after the last injection. The MF increased to 8-fold and 13-fold over the control at 7 and 35 days, respectively, after the last injection and then slightly declined at 70 days. These kinetics are similar to those reported for ENU-treated lacZ transgenic mice. This novel transgenic rat could be useful for investigating species differences between rats and mice in their response to genotoxic agents.

Animals↗