Biomedical subjects

Ryohei Katoh

Publications and source records attributed to Ryohei Katoh.

31 records · Page 2Linked to original sources

PubMed2003

Expression of human pendrin in diseased thyroids.

We examined pendrin expression in various diseased thyroid tissues by immunohistochemistry (IHC) using antiserum raised against human pendrin and by real-time quantitative RT-PCR. In normal thyroids the antiserum reacted with the apical membrane of follicular cells and its immunoreactivity was faint. In Graves' thyroids, the IHC expression of pendrin appeared in a pattern similar to that of normal thyroids but it was more extensive and stronger, especially in areas showing marked proliferation of follicular cells. The immunoreactivities of pendrin in nodular goiters varied from case to case. In follicular adenomas, pendrin was localized in the follicle-forming parts of the tumor but was negative in trabecular parts. Pendrin was negative in all follicular carcinomas, papillary carcinomas, and in one case of medullary carcinoma. In quantitive mRNA analysis, the relative values of pendrin mRNA were significantly low in papillary carcinoma (p<0.01), whereas the values in other diseased thyroids were not significantly different from those in normal thyroids. These results suggest that pendrin may play a role in thyroid hormone production as the apical porter of chloride/iodide and investigation of pendrin leads to a better understanding of functional aspects of the iodine transportation system in thyroid diseases.

Carrier Proteins↗

PubMed2003

Spatial distribution analysis of AT- and GC-rich regions in nuclei using corrected fluorescence resonance energy transfer.

We employed microscopic intensity-based fluorescence resonance energy transfer (FRET) images with correction by donor and acceptor concentrations to obtain unbiased maps of spatial distribution of the AT- and GC-rich DNA regions in nuclei. FRET images of 137 bovine aortic endothelial cells stained by the AT-specific donor Hoechst 33258 and the GC-specific acceptor 7-aminoactinomycin D were acquired and corrected for the donor and acceptor concentrations by the Gordon's method based on the three fluorescence filter sets. The corrected FRET images were quantitatively analyzed by texture analysis to correlate the spatial distribution of the AT- and GC-rich DNA regions with different phases of the cell cycle. Both visual observation and quantitative texture analysis revealed an increased number and size of the low FRET efficiency centers for cells in the G(2)/M-phases, compared to the G(1)-phase cells. We have detected cell cycle-dependent changes of the spatial organization and separation of the AT- and GC-rich DNA regions. Using the corrected FRET (cFRET) technique, we were able to detect early DNA separation stages in late interphase nuclei.

AT Rich Sequence↗

PubMed2003

The development of diabetes mellitus in Wistar rats kept on a high-fat/low-carbohydrate diet for long periods.

The present study was performed to determine the effect of long-term feeding with a high-fat/low-carbohydrate (HF/LC) diet on the onset of type-2 diabetes mellitus in normal rats. Male Wistar Imamichi rats were kept on a Control (carbohydrate 60%, fat 15%) or HF/ LC (carbohydrate 10%, fat 65%) diet for 16 mo. An intraperitoneal glucose tolerance test was performed once every 2 mo. Glucose tolerance was impaired 2 mo after the start of HF/LC diet feeding, accompanied by a decrease in the insulinogenic index. Along with time of HF/LC diet feeding, the glucose tolerance was further deteriorated with more serious impairment of insulin secretion and sensitivity. At the end of the experiment, 15 of 18 rats in the HF/LC group were diabetic, whereas only 4 of 17 rats in the Control group were diabetic. The present results demonstrate that longterm feeding with a HF/LC diet decreases the secretion and sensitivity of insulin, and induces diabetes mellitus in rats. Furthermore, long-term feeding with such a diet may produce adverse effects on the blood plasma lipid profile, with elevated levels of triglycerides, nonesterified fatty acids, total cholesterol, and reduced levels of high density protein cholesterol in the plasma.

Animals↗

PubMed2003

[Development of severe aplastic anemia in a girl with Hashimoto's thyroiditis and papillary thyroid carcinoma].

A 14-year-old girl was admitted because of general fatigue and cervical lymphadenopathy. She showed bilateral struma (IInd degree) and enlargement of her left cervical lymph nodes. Laboratory data revealed neutropenia (219/microliter) and thrombocytopenia (Plt 5.1 x 10(4)/microliter) with mild anemia (Hb 11.1 g/dl), and the bone marrow aspirate and biopsy specimens showed hypocellularity. In addition, auto-antibodies against thyroid peroxidase (TPO) and thyroglobulin (TG) were highly elevated. Computed tomography of the neck showed a nodule in the left thyroid lobe with marked lymphadenopathy, and fine needle aspiration biopsy demonstrated papillary thyroid carcinoma with Hashimoto's thyroiditis and metastasis to the lymph nodes. One month after left thyroid lobectomy and cervical lymphadenectomy, the patient's condition progressed to very severe aplastic anemia, and she received immunosuppressive therapy consisting of cyclosporin A and anti-thymocyte globulin. Hematologically, partial and complete responses were obtained three and six months later, respectively. Of interest, anti-TPO and TG antibody titers remarkably decreased after immunosuppressive therapy. The patient had HLA-DR 2(DRB 1*1501) and DR 8(DRB 1*0802). The former is frequently found in patients with cyclosporin A-dependent aplastic anemia, and the latter is frequently found in Asian patients with Hashimoto's thyroiditis, suggesting an underlying autoimmune background for the simultaneous outbreak of aplastic anemia and Hashimoto's thyroiditis complicated by thyroid carcinoma.

Adolescent↗

PubMed2002

Detection of underlying characteristics of nuclear chromatin patterns of thyroid tumor cells using texture and factor analyses.

BACKGROUND: Aspiration biopsy cytology of thyroid tumors has been used more frequently in recent times to differentiate between malignant and benign lesions. Chromatin patterns of the tumor cell nuclei are one of most important factors for cytologic diagnosis. The interpretation of nuclear chromatin patterns is subjective and more difficult than that of nuclear size or shape. In the present report, we investigated how to detect underlying chromatin characteristics of benign and malignant thyroid tumor cells by means of texture and factor analyses. METHODS: We employed a computer-aided system in which light microscopy was combined with an image processor and monochrome camera. Using this system, 100 randomly selected cells in a Papanicolaou stained, aspiration biopsy cytologic smear in each case of 39 benign and malignant thyroid tumor cases were digitized. We applied two-dimensional and higher texture analyses with the use of co-occurrence and run-length matrices to analyze the chromatin patterns. Factor analysis was used to determine whether a large number of independent variables actually measured one or more underlying common variables. RESULTS: According to parameters with high factor-loading values, the morphologic chromatin characters were classified into three categories according to heterogeneity, contrast, and homogeneity of chromatin patterns. On the basis of analyses with these morphologic categories, nuclei of papillary carcinoma showed higher contrast of chromatin patterns than did those of the benign group. Moreover, there was a variety of contrasting chromatin patterns among cells in each papillary carcinoma case in comparison with the benign group. In contrast, follicular carcinomas showed a significant difference in the standard deviation of factor 3, which indicated more monotonous chromatin patterns among cells in each follicular carcinoma case than in each benign case. CONCLUSION: We believe that this technique, using texture and factor analyses, is useful in the detection of underlying characteristics of nuclear chromatin patterns in aspiration biopsy cytology.

Adenocarcinoma, Follicular↗

PubMed2002

Mutation of ras oncogene in di-isopropanolnitrosamine-induced rat thyroid carcinogenesis.

To clarify the role of ras gene mutation in thyroid tumorigenesis, DNAs extracted from various rat thyroid lesions induced by di-isopropanolnitrosamine (DIPN) administration were analyzed using the microdissection-polymerase chain reaction-direct sequence (MD-PCR-DS) method. The MD-PCR-DS method revealed that K- ras gene mutation (G-A transition at codon 12) was frequently detected in nodular lesions (incidence of mutation 75%) and absent in diffuse hyperplastic and pre-nodular lesions. Although the incidence of mutation in nodular lesions was not correlated with the histological type (type 2A 76%; type 2B 84%; and type 3 71%) or treatment period (15 weeks 84% and 30 weeks 71%), it was correlated with the administration method (single injection 55% and serial injection 91%). In conclusion, K- ras mutation plays an important role in DIPN-induced rat thyroid tumorigenesis, possibly regarded as an early event in the tumorigenic process.

Animals↗

PubMed2002

Observer variation of encapsulated follicular lesions of the thyroid gland.

Although histologic definition of follicular thyroid lesions is readily available, application of the diagnostic criteria and personal experience may lead to disagreement among pathologists. To investigate interobserver variation in assessment of encapsulated follicular lesions, eight pathologists (four American and four Japanese) reviewed the same hematoxylin and eosin-stained slide of each of 21 cases of thyroid lesions showing encapsulation and follicular growth pattern. In 10% of the cases, there was complete agreement. At least seven pathologists agreed on the diagnosis in 29% of the cases, and at least six in 76% of the cases. American and Japanese pathologists agreed among themselves in 33% and 52% of cases, respectively. The frequency of diagnosis of adenomatous goiter among Japanese pathologists (31%) was considerably higher than that among American pathologists (6%). In contrast, the frequency of diagnosis (25%) of papillary carcinoma among American pathologists was considerably higher than that (4%) among Japanese pathologists. Our analysis revealed three main factors affecting observer variation: 1) interpretation of the significance of microfollicles intimately related to capillaries within the tumor capsule, 2) evaluation of what constituted the type of nuclear clearing indicative of papillary carcinoma, and 3) absence of clear morphologic criteria for separation of adenomatous goiter and follicular adenoma. To reduce observer variation of encapsulated follicular lesions, it will be necessary to provide more explicit criteria for diagnosis.

Adenoma↗

PubMed2002

Expression of thyroid transcription factor-1 in normal and neoplastic lung tissues.

The expression of thyroid transcription factor-1 in normal and neoplastic tissues and cell lines of the human lung was investigated using immunohistochemistry and in situ hybridization in conjunction with reverse transcription polymerase chain reaction. In normal lung tissues, immunoproducts of thyroid transcription factor-1 were observed in the nuclei of alveolar cells and bronchiolar cells. Interestingly, in distal bronchioles, immunohistochemistry and in situ hybridization revealed that thyroid transcription factor-1 was present not only in nonciliated cells (Clara cells) but also in ciliated cells and basal cells. In neoplastic tissues, thyroid transcription factor-1 was demonstrated in adenocarcinomas and small cell lung carcinomas with high frequency: 96% and 89% of cases, respectively. Thyroid transcription factor-1 was not detected in squamous cell carcinomas and large cell carcinomas. The strong immunoreactivity of thyroid transcription factor-1 or simultaneous expressions of thyroid transcription factor-1 and surfactant protein A tended to correlate with the differentiation phenotypes in adenocarcinomas; they were more frequently present in the well-differentiated type than were moderately and/or poorly differentiated types. By reverse transcription polymerase chain reaction, expression of thyroid transcription factor-1 messenger RNA was observed in squamous cell carcinomas in addition to in adenocarcinomas and small cell lung carcinomas, and this finding was confirmed in the cell lines from squamous cell carcinomas. Only one case of 99 adenocarcinomas that originated in various organs other than lung and thyroid immunohistochemically expressed thyroid transcription factor-1. Our results suggest that thyroid transcription factor-1 can play an important role for the maintenance and/or differentiation process in bronchiolar and alveolar cells. Thyroid transcription factor-1 expression associates with histologic types and/or differentiation of lung cancers and can be a valuable marker for the better understanding of their biological nature and pathological behavior.

Adenocarcinoma↗

PubMed2002

Expression of PDS/Pds, the Pendred syndrome gene, in endometrium.

Expression of the Pendred syndrome gene (PDS/Pds) is thought to be responsible for the iodide transport in the thyroid as well as the formation and function of the inner ear. Its mRNA is also expressed in the kidney and placenta. We report here that PDS and its encoded protein (pendrin) are also expressed in the endometrium. The RNA levels of rat PDS in the endometrium and kidney were much higher than those of the thyroid, opposite of the pattern of RNA expression in humans. In human endometrium, pendrin localization changed from the basal to apical surfaces of the epithelium during progression of the menstrual cycle. This suggests a possible role for pendrin in cationic ion transport required to maintain the physiological function of the endometrium. Since there is no evidence of endometrial abnormalities in patients with Pendred syndrome, it suggests the existence of a compensatory mechanisms for pendrin's function in the uterus.

Animals↗

PubMed2002

Thyroid gland: international case conference.

The cases of five thyroid tumors were presented and discussed at an international case conference held during the 5th Annual Meeting of the Japanese Endocrine Pathology Society. There was significant disagreement among six pathologists who studied the cases. In this article, we present two of the cases, attempt to explain the reason for disagreement in their diagnoses, and propose what should be done to obtain better consensus in diagnosis.

Adenocarcinoma, Follicular↗

PubMed1997

Effects of Propyithiouracil (PTU) Administration on the Synthesis and Secretion of Thyroglobulin in the Rat Thyroid Gland: A Quantitative Immuno-electron Microscopic Study Using Immunogold Technique.

To clarify the effects of an antithyroid drug on the kinetics of thyroglobulin synthesis, secretion, and reabsorption in the thyroid follicles, propylthiouracil (PTU) was administered to rats and the thyroid glands were examined by a refined post-embedding immunogold technique during and after withdrawal of PTU. Seven-wk-old male Wistar rats were administered with S mg of PTU/d through a gastric tube, and sacrificed at 1 and 2 wk of administration and at 1, 2, and 3 d, and 1, 2, 3, and 4 wk, after discontinuation. The administration of PTU caused a remarkable dilatation of the rER and Golgi apparatus, but these areas gradually recovered after withdrawal of PTU. During the experiment, no significant change in the density of thyroglobulin (Tg) was observed except for a transient increase immediately after withdrawal of PTU. The expression of Tg on subapical vesicles (SV) and follicular colloid took a relatively parallel course; increasing during administration of PTU and decreasing with a transient peak immediately after treatment was discontinued. In contrast to the remarkable changes in the morphology of compartments involved in Tg synthesis, the development of colloid droplets and formation of secondary lysosomes were suppressed during and after discontinuing administration of PTU. However, the basic pattern of the gradient of Tg density among the cellular compartments was essentially retained in the experimental group. Thus the present immunoelectron-microscopic study provided evidence that administration of PTU stimulates the synthesis and secretion of Tg in the follicular epithelium in vivo, and, also, suppresses reabsorption and degradation of Tg. Further, it was speculated that the density gradient of Tg among the compartments involved in Tg synthesis, secretion and storage is regulated by an unknown constitutive mechanism and not by the thyroid-stimulating hormone (TSH)-TSH receptor-mediated system.

Journal Article↗

PubMedDate not supplied

Application of microscopic Forster resonance energy transfer to cytological diagnosis of the thyroid tumors.

We propose a novel application of microscopic Forster resonance energy transfer (FRET) to clinical cytological diagnosis based on sensitive measurements of distance changes between fluorescently labeled deoxyribose nucleic acid (DNA) molecules. We have employed the microscopic FRET imaging for investigation of six papillary carcinomas and eight benign cases. In each case the FRET images of 20 cells stained by the AT-specific donor Hoechst 33258 and the GC-specific acceptor 7-aminoactinomycin D were acquired and analyzed by texture analysis. We have not found significant difference of the mean FRET efficiency between the benign and malignant groups. On the other hand, the texture analysis revealed a significant difference of the intranuclear spatial distribution of FRET efficiencies between the benign and malignant groups. The results indicate that despite the similar average distance between the AT- and the GC-rich DNA segments in the papillary carcinomas and the benign cases, the former has more heterogeneous distribution of the AT- and the GC-rich DNA segments in nuclei compared to the benign groups. We have demonstrated that the FRET imaging is a helpful tool for the medical cytological diagnosis of human tumors by giving information on the chromatin topology on the scale below the resolution of conventional optical microscopes. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Artificial Intelligence↗

PubMedDate not supplied

Unusual cytologic findings in low grade papillary transitional cell carcinoma.

OBJECTIVE: To describe cases of low grade papillary transitional cell carcinoma (LG-pTCC) with a low nuclear cytoplasmic (N/C) ratio and unusual cytologic patterns with many isolated, single neoplastic cells. STUDY DESIGN: We defined the following unusual cytologic findings as "isolated, single cell pattern": (1) numerous single cells sometimes with a few flat cell clusters; (2) very low N/C ratio; (3) angulation of cytoplasmic contour; (4) pale, homogeneous cytoplasm; (5) hyperchromatic nuclei with an uneven contour; (6) monotonous cytologic appearance; and (7) clear background. We studied 2,956 cytologic specimens of voided urine from 114 LG-pTCC patients at our university hospital during a 10-year period. RESULTS: Thirty-six specimens had the isolated, single cell pattern. The isolated, single cell pattern showed less celllular atypia than does the typical pattern of LG-pTCC. On histology the cases with the isolated, single cell pattern showed a papillary structure with an erosive surface and were composed of mildly atypical neoplastic cells with very low N/C ratios. CONCLUSION: Some LG-pTCCs show many single, atypical transitional cells.

Carcinoma, Papillary↗