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Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 91 records · Page 5Linked to original sources
PubMed2001

Simultaneous resection of pancreas and liver metastases from different metachronous primary cancers.

Resection of a pancreatic head tumor and partial resection of the liver for metastatic lesions were carried out simultaneously in a 72-year-old woman. The patient had a history of two previous operations, right nephrectomy for renal cell carcinoma (clear cell type), done 14 years previously, and an Autincloss procedure for cancer of the left breast (solid tubular carcinoma); (T1N0M0; stage I) done 7 years previously. At the current presentation, preoperative radiographic examination showed a hypervascular tumor in each of the pancreatic and hepatic lesions, but with different patterns. On the basis of histological findings in the two resected specimens, it was difficult to establish whether the hepatic tumor originated from the renal cell carcinoma or the breast cancer, but postoperative immunohistochemical studies for carcinoembryonic antigen (CEA), estrogen receptors, and gross cystic disease fluid protein (GCDFP)-15 showed that the pancreatic tumor had metastasized from the renal cell carcinoma, and the liver tumor from the breast cancer. The immunohistochemical investigation of different markers thus proved to be useful in making the final diagnosis of metastatic lesions from different and metachronous cancers.

Aged↗
PubMed2001

Minimum ten-year follow-up clinical and radiographic results of Mark I and Mark II Lord type femoral component in total hip arthroplasty.

The purpose of this study was to evaluate the clinical and radiographic results in 103 hips in 88 patients who had cementless primary Lord type femoral component (stem), with a mean follow-up of 11.8 years (range, 10 to 16 years). The original diagnoses were: osteoarthritis in 77 hips, rheumatoid arthritis in 15, and osteonecrosis of the femoral head in 11. Clinical results were assessed using the Harris hip score. Biological fixation, stem full-fit ratio in the intramedullary canal, and bone remodeling were evaluated by X-ray findings. The average clinical hip scores were: 47.1 points preoperatively, 81.7 points at 1 year, 86.6 points at 5 years, 79.0 points at 10 years, and 76.8 points at 15 years. By setting the endpoint at the time when loosening was radiologically confirmed, the 10-year survivorship of the femoral component was 96.9%, and the 16-year survivorship was 95.9%. The full-fit ratio between the bone implant interface just after surgery showed a significant relationship to stability of the femoral component. The decrease in the hip score at 10 years was caused by aseptic loosening of the acetabular threaded cup. However, the femoral component was stable for more than 10 years after the operation. In conclusion, long-term acceptable durability can be expected with the Lord type femoral component.

Adult↗
PubMed2001

Increased exocytosis of secretory granules in contrast to reduced serum hormone levels in pituitary adenomas of humans and rats treated with dopamine agonist.

The release of secretory granules outside the cells increased in frequency, in inverse proportion to the marked decrease in serum prolactin (PRL) levels in human prolactin-secreting adenomas (PRLomas) treated with bromocriptine (CB), a dopamine agonist. Rat pituitary adenomas induced by diethylstilbestrol also showed an increase in exocytosis of the granules despite a reduction in serum PRL levels after CB treatment. To elucidate this curious phenomenon, which is contrary to current general knowledge that serum hormone levels are sustained by the exocytosis of the secretory granules, we combined morphometric analysis with analyses using a cell fractionation technique and immunocytochemistry. The results indicated that the proteins in secretory granules consisted of 90% nonhormonal proteins and 10% PRL. CB treatment did not change the levels of the former, while the levels of the latter were markedly reduced. Immunocytochemistry, using a protein-A gold method, revealed that the secretory granules in rats treated with CB contained fewer PRL molecules than the controls. Serum PRL elevation caused by the exocytoses, estimated by counting the exocytotic granules, were markedly lower (less than 10%) in CB-treated rats than in the controls. It was suggested that, after CB treatment, the composition of secretory granules altered, or that nonhormonal constituents in the granules disintegrated more slowly, and that the granules became detectable at the site of release for a longer period. Consequently, although granules that appear ultrastructurally similar to those in untreated adenomas are observed to be more frequently released in treated adenomas, it seems that they no longer contribute to raising the serum PRL levels.

Adenoma↗
PubMed2001

Reassessment of monoethylglycinexylidide as preoperative liver function test in a rat model of liver cirrhosis and man.

It is known that lidocaine is rapidly metabolized by the hepatic cytochrome P-450 system to form monoethylglycinexylidide (MEGX), its primary metabolite. We analyzed serum MEGX levels experimentally and clinically by fluorescent polarization immunoassay to reassess preoperative liver microsome functions. EXPERIMENTAL STUDY: Liver cirrhosis was produced in rats by intra-abdominal injection of thioacetamide. MEGX, indocyanine green test (ICG), and liver biochemical variables were measured periodically. Then, survival rates were assessed after the rats received a 70% hepatectomy. CLINICAL STUDY: MEGX levels were measured in various human patients with chronic hepatitis or liver cirrhosis who underwent hepatectomy. Serum MEGX levels significantly dropped and ICG levels significantly rose with macroscopic and histologic progression of liver cirrhosis in rats. The MEGX levels correlated closely with albumin levels and ICG. Preoperative MEGX and ICG levels of the mortal group of rats differed significantly from those of the survival group with 70% hepatectomy. Furthermore, 100% of the rats with MEGX levels above 40 ng/ml and ICG levels below 1.0%. In the clinical study, MEGX levels were significantly lower in patients with chronic hepatitis or liver cirrhosis than in healthy volunteers and correlated significantly with liver function tests such as albumin, Fischer's ratio, prothrombin time, hepaplastin and ICG. A significant difference was found in MEGX levels between patients receiving lobectomy and those receiving subsegmentectomy or partial hepatectomy. All patients tolerated their operations. Our data indicate that the MEGX test combined with ICG test and Child-Pugh classification is a better predictor of residual liver reserve capacity, and the analysis of hepatic MEGX formation might prove useful for rapid and reliable assessment liver function and choice of surgical treatment.

Alanine Transaminase↗
PubMed2001

Expression of 25 kDa heat shock protein by synovial type B cells of the mouse temporomandibular joint.

Earlier studies have demonstrated immunoreactivity for heat shock protein 25 (Hsp25) in type B synovial lining cells of the rat temporomandibular joint, and also the presence of characteristic cytoplasmic processes in these cells, but it is unclear whether or not the type B cells in other animals possess such elaborate cytoplasmic projections and as there is as yet no evidence for the synthesis of this protein by these cells. For these reasons, the expression of Hsp25 was investigated in the synovial membrane of the mouse temporomandibular joint by immunocytochemistry and by in situ hybridization using a specific cRNA probe. Intense immunoreaction for Hsp25 was found in the cytoplasm of certain synovial lining cells that were identified as type B by immunoelectron-microscopy. These Hsp25-positive cells had slender cytoplasmic processes, either projecting towards or covering the synovial surface. Morphological differences between cytoplasmic processes seemed to depend on the location of the type B cell bodies. In situ hybridization showed intense signals for Hsp25 mRNA in the synovial lining cells, suggesting that the type B cells produce, rather than resorb, Hsp25. These findings indicate that Hsp25 is a useful marker for the identification of the synovial type B cells in the temporomandibular joint. It is further hypothesized that Hsp25 in type B cells is involved in maintaining their specific profile and epithelial-like arrangement, and in protecting against mechanical stress.

Animals↗
PubMed2001

Eosinophil-induced liver injury: an experimental model using IL-5 transgenic mice.

BACKGROUND/AIMS: In certain liver diseases, activated eosinophils are considered to be important effector cells in addition to T-cell-mediated cytotoxicity. No experimental model, however, has been developed for in vivo analysis of the cytotoxic mechanisms. METHODS: Interleukin-5 (IL-5) transgenic mice (C3H/HeN-TgN(IL-5)Imeg), which exhibit marked eosinophilia without liver injury, were injected once with 25 microg of lipopolysaccharide (LPS) intraperitoneally. The mice were sacrificed weekly and eosinophilic injuries were assessed microscopically. To clarify the role of Kupffer cells and tumor necrosis factor-alpha (TNF-alpha) in the liver injury, gadolinium chloride (GdCl3) and anti-TNF-alpha neutralizing antibody were administrated before the LPS injection. RESULTS: Two weeks after injection, transgenic mice exhibited marked infiltration of eosinophils and extensive lobular necrosis. Transmigration of eosinophils through vascular endothelium and degranulation of eosinophil cytotoxic granules in inflamed areas were observed. These eosinophilic injuries were transient, but liver-specific. Pre-administration of GdCl3 and anti-TNF-alpha markedly reduced the hepatic inflammation, suggesting that LPS-activated Kupffer cells play a key role in producing the cytotoxicity of eosinophils by releasing TNF-alpha. CONCLUSIONS: We have established an experimental model of eosinophil-induced liver injury using IL-5 transgenic mice. Since this model is simple and highly reproducible, it will be useful for analysis of in vivo cytotoxic mechanisms of eosinophils.

Animals↗
PubMed2001

Variation in the olfactory response of 13 populations of the predatory mite Amblyseius womersleyi to Tetranychus urticae-infested plant volatiles (Acari: Phytoseiidae, Tetranychidae).

We studied the response of the predatory mite Amblyseius womersleyi collected in 13 different sites in Japan toward Terranychus urticae-infested kidney bean leaf volatiles in a Y-tube olfactometer. The predatory mites were collected from eight plant species infested by one of three tetranychid mite species. The predators' responses to the infested-leaf volatiles varied from 33% to 97% among the populations. The predators collected at 10 sites showed a significant preference for infested-leaf volatiles, whereas those collected at three tea plantations did not distinguish between the infested- and uninfested-leaf volatiles. We discussed the possible factors that affected the olfactory response of A. womersleyi towards the infested leaf volatiles.

Animals↗
PubMed2001

HTLV-1 proviruses encoding non-functional TAX in adult T-cell leukemia.

Adult T-cell leukemia (ATL) is associated with prior infection with human T-cell leukemia virus type 1 (HTLV-1). TAX, the major transactivator of HTLV-1, has been implicated in the immortalization of infected T-cells, but molecular mechanisms of in vivo malignant cell transformation induced by HTLV-1 remain unclear. To investigate the role of TAX in the monoclonal proliferation of ATL cells, we determined the nucleotide sequence of tax DNA clones obtained from 6 ATL patients and analysed the biological function of their products. We found that ATL cells from 2 of these patients possessed tax with a nonsense or frame-shift mutation resulting in the premature termination of its protein product, which was no longer functional. This strongly argued against an indispensable role of TAX for the maintenance of ATL cells in vivo. On the other hand, the frequency of nucleotide substitutions found in non-functional tax DNA clones from these patients was significantly lower than those in functional tax DNA clones from the others, suggesting a role for TAX in the genome instability of infected cells. Although mismatch repair defects in the microsatellite markers, including those in hMSH3, hMSH6, BAX, TGF-beta RII, and E2F4 genes, were infrequent, we found an increase in the number of CAG repeats of the E2F4 microsatellite marker in 1 patient. These findings indicate that while TAX may be a necessary prerequisite for malignant transformation of infected cells, it is not essential for the maintenance of ATL cells in vivo.

Aged↗
PubMed2001

A minimum c-erbB-2 promoter-mediated expression of herpes simplex virus thymidine kinase gene confers selective cytotoxicity of human breast cancer cells to ganciclovir.

The c-erbB-2 gene is frequently overexpressed in human breast cancers as a result of gene amplification and/or elevated transcription. We therefore examined a possible usage of promoter regions of the c-erbB-2 gene to express a suicide gene preferentially in breast cancer cells. Previous studies did not reveal the minimal promoter region that enabled transcriptional activation specific to breast cancer cells. The present reporter gene assays using deletion mutants of the c-erbB-2 promoter region demonstrated that the 251-bp (-213/+38 from the transcriptional start site), but not the 125-bp, fragment (-87/+38) could direct transcription of the linked luciferase gene better than the SV40 immediate early promoter in breast cancer cells. In contrast, the 251-bp fragment-mediated promoter activity in nonbreast cancer cells and in normal fibroblasts was lower than the activity by the SV40 promoter. The 126-bp fragment (-213/-87) thereby contains a cis-acting element(s), which is responsible for the preferential transcriptional activity in breast cancer cells. An electrophoretic mobility shift assay suggested that a possible modification of a transcriptional factor was involved in the tumor specificity. Transfection with the plasmid DNA containing the herpes simplex virus thymidine kinase gene linked with the 251-bp promoter (p256-TK) resulted in increased sensitivity to ganciclovir in breast cancer, but not in nonbreast cancer cells. Administration of ganciclovir into nude mice bearing human breast tumors that were transfected with the p256-TK DNA suppressed subsequent growth of the transplanted tumors. These results suggest that delivery of a suicide gene linked with the 251-bp c-erbB-2 promoter can be a feasible therapeutic strategy specific to breast cancer.

Animals↗
PubMed2001

Nucleotide excision repair genes are upregulated by low-dose artificial ultraviolet B: evidence of a photoprotective SOS response?

Nucleotide excision repair is a major mechanism of defense against the carcinogenic effects of ultraviolet light. Ultraviolet B causes sunburn and DNA damage in human skin. Nucleotide excision repair has been studied extensively and described in detail at the molecular level, including identification of many nucleotide excision repair-specific proteins and the genes encoding nucleotide excision repair proteins. In this study, normal human keratinocytes were exposed to increasing doses of ultraviolet B from fluorescent sunlamps, and the effect of this exposure on expression of nucleotide excision repair genes was examined. An RNase protection assay was performed to quantify transcripts from nucleotide excision repair genes, and a slot blot DNA repair activity assay was used to assess induction of the nucleotide excision repair pathway. The activity assay demonstrated that cyclobutane pyrimidine dimers were removed efficiently after exposure to low doses of ultraviolet B, but this activity was delayed significantly at higher doses. All nucleotide excision repair genes examined demonstrated a similar trend: ultraviolet B induces expression of nucleotide excision repair genes at low doses, but downregulates expression at higher doses. In addition, we show that pre-exposure of cells to low-dose ultraviolet protected keratinocytes from apoptosis following high-dose exposure. These data support the notion that nucleotide excision repair is induced in cells exposed to low doses of ultraviolet B, which may protect damaged keratinocytes from cell death; however, exposure to high doses of ultraviolet B downregulates nucleotide excision repair genes and is associated with cell death.

Apoptosis↗
PubMed2001

Autopsy case of lymphoplasmacytic lymphoma with a large submucosal tumor in the stomach.

An autopsy case of lymphoplasmacytic lymphoma with a large submucosal tumor in the stomach is presented. The patient was a 77-year-old woman with gastric lymphoma associated with Waldenstrom's macroglobulinemia of IgM-lambda type. Diagnosis was initially mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach, because gastric biopsy specimens showed epitheliotropic proliferation (lymphoepithelial lesion) of the lymphoma cells. Postmortem examination revealed a large gastric lymphoma with metastatic foci in the esophagus, larynx, trachea, lungs, spleen and lymph nodes. The bone marrow was also involved. Lymphoma cells consisted of small lymphocytoid cells occasionally admixed with blast-like large cells and a large number of plasmacytoid or plasma cells. Centrocyte-like cells were not found. Lymphoepithelial lesions were not conspicuous in autopsy specimens. Immunohistochemically, lymphoma cells reacted with CD20, CD45, CD79a, anti-IgM, anti-lambda protein and anti-BCL-2, but not with CD5, CD10, CD23 or CD38. Based on these findings, the revised diagnosis of the present case was lymphoplasmacytic lymphoma, and it highlighted the differential diagnostic problem from marginal zone B-cell lymphoma of MALT type.

Aged↗
PubMed2001

Development of a new hollow fiber silicone membrane oxygenator: in vitro study.

An experimental silicone hollow fiber membrane oxygenator for long-term extracorporeal membrane oxygenation (ECMO) was developed in our laboratory using an ultrathin silicone hollow fiber. However, the marginal gas transfer performances and a high-pressure drop in some cases were demonstrated in the initial models. In order to improve performance the following features were incorporated in the most recent oxygenator model: increasing the fiber length and total surface area, decreasing the packing density, and modifying the flow distributor. The aim of this study was to evaluate the gas transfer performances and biocompatibility of this newly improved model with in vitro experiments. According to the established method in our laboratory, in vitro studies were performed using fresh bovine blood. Gas transfer performance tests were performed at a blood flow rate of 0.5 to 6 L/min and a V/Q ratio (V = gas flow rate, Q = blood flow rate) of 2 and 3. Hemolysis tests were performed at a blood flow rate of 1 and 5 L/min. Blood pressure drop was also measured. At a blood flow rate of 1 L/min and V/Q = 3, the O2 and CO2 gas transfer rates were 72.45 +/- 1.24 and 39.87 +/- 2.92 ml/min, respectively. At a blood flow rate of 2 L/min and V/Q = 3, the O2 and CO2 gas transfer rates were 128.83 +/- 1.09 and 47.49 +/- 5.11 ml/min. Clearly, these data were superior to those obtained with previous models. As for the pressure drop and hemolytic performance, remarkable improvements were also demonstrated. These data indicate that this newly improved oxygenator is superior to the previous model and may be clinically acceptable for long-term ECMO application.

Animals↗
PubMed2001

Gas transfer performance of a hollow fiber silicone membrane oxygenator: ex vivo study.

Based on the results of in vitro studies of many experimental models, a silicone hollow fiber membrane oxygenator for pediatric cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) was developed using an ultrathin silicone hollow fiber with a 300 microm outer diameter and a wall thickness of 50 microm. In this study, we evaluated the gas transfer performance of this oxygenator simulating pediatric CPB and ECMO conditions. Two ex vivo studies in a pediatric CPB condition for 6 h and 5 ex vivo studies in an ECMO condition for 1 week were performed with venoarterial bypass using healthy calves. At a blood flow rate of 2 L/min and V/Q = 4 (V = gas flow rate, Q = blood flow rate) (pediatric CPB condition), the O2 and CO2 gas transfer rates were maintained at 97.44 +/- 8.88 (mean +/- SD) and 43.59 +/- 15.75 ml/min/m2, respectively. At a blood flow rate of 1 L/min and V/Q = 4 (ECMO condition), the O2 and CO2 gas transfer rates were maintained at 56.15 +/- 8.49 and 42.47 +/- 9.22 ml/min/m2, respectively. These data suggest that this preclinical silicone membrane hollow fiber oxygenator may be acceptable for both pediatric CPB and long-term ECMO use.

Animals↗
PubMed2001

Cementless Lord total hip arthroplasty: cup loosening common after minimum 10-year follow-up of 103 hips.

We evaluated the clinical and radiographic results of 103 (88 patients) cementless Lord total hip arthroplasty after a mean follow-up period of 12.5 (10-16) years. 77 hips had arthrosis, 15 rheumatoid arthritis and 11 osteonecrosis. The preoperative mean Harris Hip Score improved from 47 (19-66) to 87 (62-99) at 5 years, but declined to 77 (56-97) at the final examination. The survivorship of the cup, using radiographically confirmed aseptic loosening as the end point, was 63% at 10 years and 45% at 15 years and the survivorship of the stem was 97% at 10 years and 96% at 15 years. The low figures of the cup may be due to insufficient contact between the smooth-surfaced threads of the cup and the acetabular bone. Thinner polyethylene, insufficient initial bone coverage, and larger femoral head diameter were significantly related to the occurrence of loosening. We can not recommend this smooth-surfaced threaded cup because of its high failure.

Adult↗
PubMed2001

Limited proteolysis of filamin is catalyzed by caspase-3 in U937 and Jurkat cells.

Members of the caspase family have been implicated as key mediators of apoptosis in mammalian cells. However, few of their substrates are known to have physiological significance in the apoptotic process. We focused our screening for caspase substrates on cytoskeletal proteins. We found that an actin binding protein, filamin, was cleaved from 280 kDa to 170, 150, and 120 kDa major N-terminal fragments, and 135, 120, and 110 kDa major C-terminal fragments when apoptosis was induced by etoposide in both the human monoblastic leukemia cell line U937, and the human T lymphoblastic cell line Jurkat. The cleavage of filamin was blocked by a cell permeable inhibitor of caspase-3-like protease, Ac-DEVD-cho, but not by an inhibitor of caspase-1-like protease, Ac-YVAD-cho. These results suggest that filamin is cleaved by a caspase-3-like protease. To examine whether caspase-3 cleaves filamin in vitro, we prepared a recombinant active form of caspase-3 directly using a Pichia pastoris overexpression system. When we applied recombinant active caspase-3 to the cell lysate of U937 and Jurkat cells, filamin was cleaved into the same fragments seen in apoptosis-induced cells in vivo. Platelet filamin was also cleaved directly from 280 kDa to 170, 150, and 120 kDa N-terminal fragments, and the cleavage pattern was the same as observed in apoptotic human cells in vivo. These results suggest that filamin is an in vivo substrate of caspase-3.

Antineoplastic Agents↗
PubMed2001

Coexpression of the CUG-binding protein reduces DM protein kinase expression in COS cells.

Myotonic dystrophy (DM) is the most common form of adult onset muscular dystrophy. Patients have a large CTG repeat expansion in the 3' untranslated region of the DMPK gene, which encodes DM protein kinase. RNA trans-dominant models, which hypothesize that the expanded CUG trinucleotide repeat on DMPK mRNA sequesters a factor or disrupts the RNA metabolism of the DMPK mRNA itself and other mRNAs in a trans dominant manner, have been proposed. A candidate for the sequestered factor, termed CUG-binding protein (CUG-BP), exists in several alternatively spliced isoforms. We found a human isoform with a twelve base insertion (deduced amino acids Leu-Tyr-Leu-Gln) and an isoform with a three base insertion (deduced amino acid Ala) insertion. In order to elucidate the effects of CUG-BP on DMPK expression, we introduced CUG-BP and DMPK cDNA transiently into COS-7 cells. Cotransfection of CUG-BP did not significantly affect the expression of either wild type or mutant DMPK at the mRNA level. On the other hand, cotransfection of CUG-BP significantly affected the expression of both the wild type and mutant DMPKs at the protein level. This reduction was remarkable when the mutant DMPK construct was used.

Animals↗