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Biomedical subjects

T Sakuma

Publications and source records attributed to T Sakuma.

At least 19 recordsLinked to original sources
PubMed2006

[Surgical approach for lung cancer with multiple pulmonary nodules].

A computed tomography (CT) and high-resolution CT (HRCT) have provided us an increasing opportunity to find multiple small pulmonary nodules, which sometimes appear ground glass opacity (GGO). Recently, fluorodeoxyglucose-positron emission tomography (FDG-PET) had a great contribution to our assessment for these small pulmonary nodules. However, since it is yet difficult to establish a diagnosis for these nodules during preoperative workup, a surgical lung biopsy is often required for an accurate diagnosis. We have experienced 9 patients who had undergone lung resection for primary lung cancer accompanied by multiple pulmonary lesions. Since the multiple lesions were consisted of malignant and benign lesions, it is still uncertain whether excessive lung resection should be performed in such patients. In this brief article, we summarized the characteristics of the pulmonary lesions in those patients and discussed difficulty of preoperative diagnosis, viability of pulmonary resection and problems underlining a surgical treatment.

Aged↗
PubMed2005

Single burr hole surgery for the spheno-orbital fibrous dysplasia using intraoperative computed tomography.

Total removal of spheno-orbital fibrous dysplasia was achieved through intraoperative CT-assisted surgery via a burr hole. A 32-year-old man had persistent headache. Radiological studies demonstrated a small osteolytic lesion in the sphenoidal bone underneath the superior orbital fissure. Intraoperative serial CT scans showed the depth and width of the tumor within the complicated structure of the skull base. The lesion was successfully removed by CT-guided minimally invasive surgery.

Adult↗
PubMed2005

Prevalence of shiga toxin-producing Escherichia coli in dairy cattle and their products.

The main objective of this review was to assess the role of dairy cattle and their products in human infections with Shiga toxin-producing Escherichia coli (STEC). A large number of STEC strains (e.g., members of the serogroups O26, O91, O103, O111, O118, O145, and O166) have caused major outbreaks and sporadic cases of human illnesses that have ranged from mild diarrhea to the life-threatening hemolytic uremic syndrome. These illnesses were traced to O157 and non-O157 STEC. In most cases, STEC infection was attributed to consumption of ground beef or dairy products that were contaminated with cattle feces. Thus, dairy cattle are considered reservoirs of STEC and can impose a significant health risk to humans. The global nature of food supply suggests that safety concerns with beef and dairy foods will continue and the challenges facing the dairy industry will increase at the production and processing levels. In this review, published reports on STEC in dairy cattle and their products were evaluated to achieve the following specific objectives: 1) to assemble a database on human infections with STEC from dairy cattle, 2) to assess prevalence of STEC in dairy cattle, and 3) to determine the health risks associated with STEC strains from dairy cattle. The latter objective is critically important, as many dairy STEC isolates are known to be of high virulence. Fecal testing of dairy cattle worldwide showed wide ranges of prevalence rates for O157 (0.2 to 48.8%) and non-O157 STEC (0.4 to 74.0%). Of the 193 STEC serotypes of dairy cattle origin, 24 have been isolated from patients with hemolytic uremic syndrome. Such risks emphasize the importance and the need to develop long-term strategies to assure safety of foods from dairy cattle.

Animals↗
PubMed2005

Multiple reaction monitoring as a method for identifying protein posttranslational modifications.

The activity of many transcriptional regulators is significantly altered by posttranslational modifications of specific sites. For example, the activity of the muscle-restricted transcription factor family myocyte enhancer factor 2 (MEF2) is tightly controlled by phosphorylation. This modification is responsible for either an increase or a decrease in transcriptional activity, depending on the specific amino acid residues that are phosphorylated by signal-dependent kinases. Although mass spectrometry-based methods, such as precursor ion and neutral loss scans, are extremely useful for identifying unknown phosphopeptides from a complex mixture, they do not take advantage of any prior knowledge about the protein being investigated. Quite often a significant amount of information is available. This may include the primary sequence, type of phosphorylation (serine/threonine vs. tyrosine), or predicted phosphoacceptor sites (consensus peptide that is targeted by a kinase). This information can be used to predict precursor and fragment ion m/z values for a multiple reaction monitoring (MRM) experiment. By using these highly sensitive MRM experiments to trigger dependent product ion scans on a hybrid quadrupole linear ion-trap instrument, we were able to identify low levels of phosphorylation of MEF2A (a member of the MEF2 family), and alpha-casein. This method of monitoring protein phosphorylation at specific phosphoacceptor sites may prove useful in understanding the physiological regulation of protein function.

Amino Acid Sequence↗
PubMed2004

[Lung cancer with ground glass opacity diagnosed by transbronchial lung biopsy using an ultrathin bronchoscope and virtual bronchoscopy].

Although thoracic computed tomography (CT) screening indicated that there are many patients who have pulmonary shadow with ground glass opacity, it is sometimes difficult to obtain the appropriate specimens for histological diagnosis of such patients. We herein report a lung cancer patient with ground glass opacity who was diagnosed preoperatively by an ultrathin bronchoscope and virtual bronchoscopy. A 78-year-old female was admitted to our hospital due to bacterial pneumonia. At the admission, CT showed another abnormal small shadow in her right middle lobe. Since the shadow was not visible by fluoroscopy, we reconstructed the images of virtual bronchoscopy using the data obtained by multidetector CT. The location of the shadow was determined in the peripheral area of a dorsal branch of right B4aialpha. Then the transbronchial lung biopsy using an ultrathin bronchoscope with simultaneous CT guidance was performed. The histological findings of the biopsy specimens revealed that the shadow was highly suspicious for malignancy. Therefore, the right middle lobectomy was conducted, and the tumor was diagnosed as an adenocarcinoma. An ultrathin bronchoscope with virtual bronchoscopy is useful to diagnose a pulmonary shadow with ground glass opacity.

Aged↗
PubMed2003

Intramucosal adenocarcinoma of the appendix: how to find and how to treat.

A colonoscopic examination of a 58-year-old man revealed a small elevated lesion inside the orifice of the appendix. Using a polypectomy snare, a nodular polypoid lesion with a diameter of ca. 20 mm was removed from the lumen of the appendix. Histopathology showed that it was a well-differentiated adenocarcinoma. This is the first report of an intramucosal adenocarcinoma of the appendix diagnosed preoperatively; laparoscopy-assisted colectomy with a D2 lymph-node dissection was carried out. Endoscopists should consider an appendiceal tumor when an erosion, elevation, or deformity is seen in the head of the cecum.

Adenocarcinoma↗
PubMed2002

A highly potent 26,27-Hexafluoro-1a,25-dihydroxyvitamin D3 on calcification in SV40-transformed human fetal osteoblastic cells.

26,27-hexafluoro-1a,25-dihydroxyvitamin D3 (F6-D3) has been reported to be 5-10 times more potent than 1a,25-dihydroxyvitamin D3[1,25(OH)2D3] in biological systems in vivo and in vitro. However, the effect of F6-D3 on bone formation has yet to be clarified. In the present study, we investigated the effect of F6-D3 on SV40-transfected human fetal osteoblastic cells (SV-HFO) and found it to be about 100 times greater than that of 1,25(OH)2D3 in stimulating calcification. F6-D3 was also about 100 times more effective than 1,25(OH)2D3 in enhancing the expression of mRNA for alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). In the presence of 10?8 M F6-D3 and 10?6 M 1,25(OH)2D3, the calcification began on day 9 and increased up to day 19. Expression of mRNA for ALP and OCN reached a maximum on day 4 and thereafter declined. On the other hand, when osteoblastic cells were incubated with a low level of [1b-3H]-F6-D3- or [1b-3H]-1,25(OH)2D3, each radioactive peak could not be detected. However, on the incubation of osteoblastic cells and radioactive substrate in the presence of ketoconazole, a selective inhibitor of CYP24, a clear peak for each substrate was detected. This suggested that F6-D3 as well as 1,25(OH)2D3 is metabolized by CYP24. Osteoblastic cells were incubated with 10?8 M[1b-3H]-F6-D3 or 10?8 M[1b-3H]-1,25(OH)2D3 for 4, 9, and 14 days. A small peak of 1,25(OH)2D3 was observed and thereafter its level decreased. In addition, two unknown peaks increased when the culture period was extended. In the case of F6-D3, peaks of F6-D3 and 26,27-hexafluoro-23-oxo-1a,25(OH)2D3(23-oxo-F6) were clearly detected, the latter being about 4 times higher than the former. Both peaks was retained up to day 14. The amount of unlabeled F6-D3 and 23-oxo-F6 calculated from the specific radioactivity in the cells may be similar to the amount of 1,25(OH)2D3 and its metabolites. The strong activity of F6-D3 in stimulating calcification may be due to the fact that F6-D3 is much more potent than 1,25(OH)2D3 in enhancing the expression of mRNA for ALP, OCN, and OPN and that the amount of F6-D3 and 23-oxo-F6 accumulated in the cells is much greater than that of 1,25(OH)2D3 and its metabolite.

Alkaline Phosphatase↗
PubMed2001

Sex-associated expression of mouse hepatic and renal CYP2B enzymes by glucocorticoid hormones.

The expression of Cyp2b9 and Cyp2b10 genes was investigated in kidney, liver, and cultured hepatocytes of adult C57BL/6NCrj mice. The constitutive expression level of CYP2B mRNA in kidney was higher in female than in male mice, as it was in the liver where more CYP2B9 than CYP2B10 was expressed in the females, and more CYP2B10 was expressed in the males. After treatment with dexamethasone (Dex), induction of CYP2B10 mRNA and protein in the kidneys was far greater in male than in female mice. In contrast to Dex, phenobarbital (PB), pregnenolone-16 alpha-carbonitrile (PCN), and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) did not induce the expression of the Cyp2b gene in the kidneys of either sex. In the liver, PB, PCN, and DDT induced both CYP2B9 and CYP2B10 in both sexes to the same extent, whereas Dex induced only CYP2B10 and simultaneously suppressed CYP2B9. Dex-inducible expression of CYP2B mRNA was decreased by 11 beta-[4-dimethylamino]phenyl-17 beta-hydroxy-17-[1-propynyl]estra-4,9-dien-3-one (RU-486), in both the kidneys and liver from male mice, and in cultured hepatocytes. However, RU-486 itself induced the expression of CYP2B mRNA in female liver and cultured hepatocytes. Interestingly, RU-486 increased PB-inducible expression of these species in cultured hepatocytes. Gonadectomy increased the expression of CYP2B mRNA in untreated male liver, but suppressed Dex-induced expression in the kidneys of both sexes. These observations suggest that (a) there are multiple regulatory pathways in the expression of Cyp2b genes, one of which used by Dex is mediated via the glucocorticoid receptor, which is different from that used by PB, and (b) sex hormones play a role in the regulation of the sex-dependent expression of Cyp2b genes in the mouse.

Animals↗
PubMed2001

The role of hinge domain in heterodimerization and specific DNA recognition by nuclear receptors.

Four structural domains are characteristic of the members of the nuclear receptor superfamily. The hinge (D) domain which is located between the DNA binding (C) domain and the ligand binding (EF) domain, is less conserved among the nuclear receptors. In this study, we investigated the effects of the D domain on receptor function with regard to ligand binding, protein-protein interaction and DNA recognition. We found that EF domain of TR lacked T3 binding activity and additional D domain was required for its ligand binding. Using pull down assays and two-hybrid assays, we also demonstrated that the EF domain of TR did not dimerize with TR or RXR in solution, while the DEF domain was able to homo-and heterodimerize with RXR. In contrast, the RXR EF domain alone was able to heterodimerize with TR. The D domain of TR is required but that of RXR is not necessary for the interaction. We further demonstrated that the D domain was required for receptor specific DNA recognition. The ABC domain of vitamin D receptor (VDR) and TR(DEF) chimeric receptor could not bind to VDR response element (VDRE). Addition of own D domain of VDR to the ABC domain enables the chimeric receptor to bind VDRE and transactivate. The D domain of TR cannot substitute for that of VDR in context of specific DNA recognition. These data suggest that the D domain is important to maintain the integrity of the functional structure of the nuclear receptors.

Animals↗
PubMed2001

Inhibitory effect of the mi transcription factor encoded by the mutant mi allele on GA binding protein-mediated transcript expression in mouse mast cells.

The mi transcription factor (MITF) is a basic-helix-loop-helix leucine zipper (bHLH-Zip) transcription factor that is important for the development of mast cells. Mast cells of mi/mi genotype express normal amounts of abnormal MITF (mi-MITF), whereas mast cells of tg/tg genotype do not express any MITFs. The synthesis of heparin is abnormal in the skin mast cells of mi/mi mice. Because N-deacetylase/N-sulfotransferase 2 (NDST-2) is essential for the synthesis of heparin, the amount of NDST-2 messenger RNA (mRNA) was compared among cultured mast cells (CMCs) of +/+, mi/mi, and tg/tg genotypes. The NDST-2 mRNA was detected by in situ hybridization in the skin mast cells of +/+ and tg/tg mice, but not in the skin mast cells of mi/mi mice. The amount of NDST-2 mRNA decreased significantly in CMCs derived from mi/mi mice when compared to the values of +/+ and tg/tg mice, suggesting that the defective form of MITF inhibited the expression of the NDST-2 transcript. The expression of NDST-2 transcript was mediated by the GGAA motif located in the 5'-untranslated region. GA binding protein (GABP) bound the GGAA motif and increased the amount of NDST-2 transcript. The mi-MITF appeared to inhibit the ability of GABP to express NDST-2 transcript by disturbing its nuclear localization. This is the first study to show that expression of an abnormal form of a bHLH-Zip transcription factor can dramatically alter the intracellular location of another DNA/RNA binding factor, which in turn brings about profound and unexpected consequences on transcript expression.

5' Untranslated Regions↗
PubMed2001

Analysis of tamoxifen and its metabolites in synthetic gastric fluid digests and urine samples using high-performance liquid chromatography with electrospray mass spectrometry.

We report on the transformation of tamoxifen at 37 degrees C in synthetic gastric fluid as studied by high-performance liquid chromatography with triple quadrupole mass spectrometry. The major transformation products detected were (E)-isomer of tamoxifen, metabolite D, and several unidentified components having m/z 404. Addition of pepsin to the gastric fluid inhibited formation of all of these products. We analyzed several urine samples from breast cancer patients undergoing tamoxifen treatment. Metabolite D was identified in the urine samples and in the gastric fluid digest at a retention time of 22.0 min eluting from a reversed-phase HPLC column. Although several metabolites were found in all the urine samples of patients, some metabolites were detected in one sample but not others, suggesting tamoxifen metabolism varies in patients.

Breast Neoplasms↗
PubMed2001

Optimal time for predicting myocardial viability after successful primary angioplasty in acute myocardial infarction: a study using myocardial contrast echocardiography.

This study sought to elucidate serial changes in microvascular integrity during papaverine-induced hyperemia in the risk area for myocardial infarction. In addition, we attempted to determine the optimal time for predicting myocardial viability. Seventy-two patients who underwent serial myocardial contrast echocardiography (MCE) before and shortly after (day 1), 1 day (day 2), and 3 weeks (day 21) after recanalization were studied. In 18 of 72 patients, MCE was performed at baseline and during hyperemia using selective intracoronary infusion of papaverine. Both the peak grayscale ratio (PGSR) within the risk area, and the no- and low-reflow ratio (LR ratio) were analyzed in each stage. Left ventricular regional wall motion (RWM) was determined 6 months after recanalization. The correlation coefficient between PGSR with papaverine on day 1 and that on day 2 was 0.54 (p = 0.02); it was 0.50 (p = 0.04) between day 1 and day 21, and 0.82 (p = 0.001) between day 2 and day 21. On day 1, the correlation coefficient between the LR ratio with papaverine and RWM was 0.60 (p = 0.02), which changed to 0.72 (p = 0.003) on day 2 and 0.54 (p = 0.04) on day 21, respectively. The best time to predict viable myocardium was established on day 2 by receiver operating characteristics curves. ST-segment re-elevation, elapsed time from onset to recanalization, and antecedent angina pectoris were independent factors for PGSR on day 2 using stepwise and multiple linear regression analysis. This study suggests that the optimal time to estimate microvascular integrity for predicting myocardial viability might be 1 day after recanalization, which is neither shortly after recanalization nor during the convalescent stage.

Aged↗
PubMed2001

Localization of estradiol-responsive region in the phenobarbital-responsive enhancer module of mouse Cyp2b-10 gene.

The mouse Cyp2b-10 gene is inducible by treatment with estradiol as well as so-called phenobarbital (PB)-like inducers. To identify 5'-flanking elements responsible for induction by estradiol, we carried out reporter gene assays using a primary mouse hepatocyte culture system. Cyp2b-10 gene-driven luciferase activities were induced by estradiol as well as PB in this system. Deletion analysis demonstrated that the sequence contained within the region from -2331 bp to -2281 bp was responsible for the estradiol-induced luciferase activity. This region corresponds to the core element of PB-responsive enhancer module (PBREM). Several nucleotide mutations in the putative binding sites of the PBREM core element showed that the NR1 site was required for estradiol induction, and the same element was required for PB induction. These results indicate that estradiol induces Cyp2b-10 gene expression via PBREM.

Animals↗
PubMed2001

Stimulative effect of cadmium on prostaglandin E2 production in primary mouse osteoblastic cells.

We have reported that cadmium (Cd) stimulates bone resorption via prostaglandin E2 (PGE2), which is mainly produced in osteoblasts. Prostaglandin (PGs) is regulated by arachidonic acid (AA) release by phospholipase A2 (PLA2) and its conversion to PGs by cyclooxygenase (COX). In the present study, we investigated the possibility that Cd-induced PGE2 synthesis was mediated through PLA2 or COX or both using primary mouse osteoblastic cells in serum-free medium. Cd at 1 microM and above stimulated 14C-AA release from 14C-AA-prelabeled osteoblastic cells. PLA2 activity of cytosolic fraction in Cd-treated cells preferentially hydrolyzed AA at the Sn2 position of phospholipids and was inhibited by arachidonyltrifluoromethyl ketone (AACOCF3), an inhibitor of cytosolic PLA2 (cPLA2). Cd at 1 microM and above increased cPLA2 activity and the level of constitutive cPLA2 mRNA. Secretory PLA2 mRNA was not detected. On the other hand, Cd at 1 microM and above stimulated PGE2 production and its production was inhibited by an inhibitor of COX-2 (NS-398). Cd at 1 microM and above markedly stimulated COX-2 mRNA expression and slightly increased the level of COX-1 mRNA. An inhibitor of COX-1 (varelylsalicylic acid) did not affect Cd-induced PGE2 production. In addition, Cd-induced PGE2 synthesis was inhibited by AA-COCF3, On the other hand, IL-1 alpha, an inducer of COX-2, did not stimulated PGE2 production in present culture system. When IL-1 alpha- or Cd-treated cells were incubated with AA for 10 minutes, IL-1 alpha-treated cells as well as Cd-treated ones caused an increase in PGE2 production. This suggests that the mechanism of Cd-induced PGE2 production is different from that of IL-1 alpha, which may require an activation of cPLA2. From these results, it was found that Cd by itself stimulated PGE2 production by two successive steps that Cd increased cPLA2 activity and then COX-2 induction.

Animals↗
PubMed2001

Molecular cause of the severe functional deficiency in osteoclasts by an arginine deletion in the basic domain of Mi transcription factor.

Severe osteopetrosis was observed in mi/mi mutant mice. However, the bone of VGA9/VGA9 mutant mice, in which Mi gene expression is undetectable, showed normal histology. No osteopetrosis was found in mi/+ mice, but was observed in VGA9/mi mice. Biochemical analysis revealed that the gene product encoded with the mi mutant allele (mi-Mi) has impaired DNA binding activity and nuclear translocation ability. Furthermore, inhibitory effects of mi-Mi were shown not only on the DNA binding activity of wild-type Mi, but also on the nuclear translocation ability of Mi, PU.1 and cFOS. The present results suggest the presence of a target gene for Mi that is essential for the proliferation/differentiation of osteoclasts.

Active Transport, Cell Nucleus↗
PubMed2001

Expression and localization of a novel Rab small G protein (Rab38) in the rat lung.

The Rab small G protein family participates in intracellular vesicle transport, including exocytosis and endocytosis. The cDNA encoding a novel Rab-related small G protein (Rab38) has been cloned from rat lung cDNA library and recorded in GenBank (accession no. M94043). However, the expression and localization of the protein in the lung remains primarily unknown. We produced polyhistidine-tagged recombinant Rab38 and a polyclonal antibody with a synthetic peptide. Immunohistochemistry demonstrated that the protein is specifically localized in alveolar type II cells and in bronchial epithelial cells. In situ hybridization using a digoxygenin-labeled RNA riboprobe clearly showed that the mRNA of the protein is localized in alveolar type II cells and bronchial epithelial cells, especially terminal airway epithelial cells. Western blot and reverse transcriptase-polymerase chain reaction showed distinct expression of the protein and mRNA in isolated alveolar type II cells, but not in alveolar macrophages. The native protein was predominantly hydrophobic and was enriched in a high-density vesicle fraction but was barely detectable in nuclear and lamellar body fractions in alveolar type II cells. Immunofluorescence cytochemistry performed on cultured alveolar type II cells showed that Rab38 distributed extensively in the cytoplasm with a distribution pattern similar to endoplasmic reticulum rather than other subcellular organelles. These results suggest that this novel rab small G protein (Rab38) mediates vesicular transport in terminal airway epithelium.

Amino Acid Sequence↗
PubMed2001

Cloning and expression pattern of a novel PEBP2 beta-binding protein (charged amino acid rich leucine zipper-1[Crl-1]) in the mouse.

PEBP2 beta/Cbf beta is the beta subunit of PEBP2/Cbf, which has been demonstrated to have important biological activities in hematopoiesis and osteogenesis. However, PEBP2 beta is ubiquitously expressed, suggesting that PEBP2 has other additionally important physiological activities. In an effort to elucidate other possible functions for PEBP2, we have isolated a novel gene that encodes a PEBP2 beta-interacting protein from a mouse cDNA library. We have called this gene Crl-1 for charged amino acid rich leucine zipper-1 (Crl-1) because it is rich in charged amino acids and contains a putative leucine zipper region. Expression studies in a 17.5 days post-coitum mouse embryo demonstrated Crl-1 expression mainly in the olfactory bulb and cerebral cortex. Post-natally, Crl-1 expression was additionally observed in the cerebellar cortex with strong expression in the hippocampus. These findings show that this novel PEBP2 beta-interacting protein is expressed mainly in subsets of neuronal cells, suggesting that Crl-1 plays some role in the developing mouse brain.

Amino Acid Sequence↗