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Biomedical subjects

M Miyazaki

Publications and source records attributed to M Miyazaki.

At least 127 records · Page 7Linked to original sources

A lipogenic diet in mice with a disruption of the stearoyl-CoA desaturase 1 gene reveals a stringent requirement of endogenous monounsaturated fatty acids for triglyceride synthesis.

Stearoyl-CoA desaturase (SCD) catalyzes the de novo biosynthesis of oleate and palmitoleate, which are the major fatty acids found in triglycerides, cholesteryl esters, and phospholipids. A high carbohydrate (lipogenic) diet induces lipogenic gene expression by sterol regulatory element binding protein 1 (SREBP-1c)-mediated gene transcription, leading to an increase in the synthesis of triglycerides. The lipogenic diet fed to mice with a null mutation in the SCD1 gene (SCD-/-) fails to induce the synthesis of triglycerides in liver, despite the induction of expression of SREBP-1 and its target genes, fatty acid synthase and glycerol-3-phosphate acyltransferase. The lipogenic diet led to a decrease in the levels of triglyceride, but an increase in the level of cholesteryl esters of saturated fatty acids. Feeding a lipogenic diet supplemented with high levels of oleate to the SCD-/- mice resulted in incorporation of oleate in the liver of SCD-/- mice, but failed to restore triglycerides to the levels in the normal mouse. Triglyceride synthesis, as measured by the incorporation of [(3)H]glycerol, was dramatically reduced in the liver of SCD-/- mouse fed a lipogenic diet compared with the normal mouse. These observations demonstrate that induction of triglyceride synthesis is highly dependent on SCD1 gene expression.

Animals↗

[Proton magnetic resonance spectroscopy of the autistic brain].

To evaluate brain dysfunction in autism, proton magnetic resonance spectroscopy (1H-MRS) was performed for 29 autistic patients (5-15 y.o.) and 19 normal children (6-14 y.o.). We obtained magnetic resonance (MR) spectra of the left and right amygdaloid-hippocampal regions and the left cerebellar hemisphere with a STEAM sequence (TR = 5000 ms, TE = 18 ms). In addition to the evaluation of signal intensity ratios, the absolute concentration of three major metabolites (N-acetylaspartate [NAA], creatine/phosphocreatine [Cr] and choline-containing substances [Cho]) was quantified by an internal reference method using unsuppressed tissue water. Although no abnormal MR images were found in the three regions examined, the signal intensity and the concentration of NAA in the left amygdaloid-hippocampal region and the left cerebellar hemisphere were reduced significantly in autistic patients compared to normal children. We speculated that this decrease in NAA reflected neuronal loss, immaturity or hypofunction in these regions. The results of our study were in agreement with those of previous studies on autism, one by neuropathological methods and the other using a single photon emission computed tomography with 99mTc HMPAO. Disorders of the amygdaloid-hippocampal region and cerebellum are considered to play an important role in the characteristic cognitive and emotional dysfunction in autism. 1H-MRS is a valuable tool to clarify the pathophysiology of autism.

Adolescent↗

[A patient with lymphoma of mucosa-associated lymphoid tissue (MALT) and adenocarcinoma in the same tumor of the lung].

A 60-year-old woman with no symptoms was found to have a mass shadow in the left lower lobe of the lung on chest radiography. Open lung biopsy and left lower lobectomy were performed. Histopathological study of the specimen revealed two distinct neoplasms. One tumor was a low grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) of the lung, while the other was an adenocarcinoma. The two neoplasms were admixed to form a composite tumor.

Adenocarcinoma↗

Insertion of a suicide gene into an immortalized human hepatocyte cell line.

For developing a bioartificial liver (BAL) device, an attractive alternative to the primary human hepatocytes would be the use of highly differentiated immortalized human hepatocytes with a safeguard. To test the feasibility, the primary human hepatocytes were immortalized by a plasmid SV3neo encoding simian virus 40 large T antigen (SV40Tag) gene. A highly differentiated hepatocyte line OUMS-29 was established. A suicide gene of herpes simplex virus-thymidine kinase (HSV-TK) was retrovirally introduced into OUMS-29 cells as a safeguard for clinical application. One of the resulting HSV-TK-positive cell lines, OUMS-29/tk, grew in chemically defined serum-free medium with the gene expression of differentiated liver functions. OUMS-29/tk cells were 100 times more sensitive to ganciclovir compared with unmodified OUMS-29 cells in in vitro experiments. We have established a tightly regulated immortalized human hepatocyte cell line. Essentially unlimited availability of OUMS-29/tk cells may be clinically useful for BAL therapy.

Antiviral Agents↗

[Basic techniques in vascular surgery].

The procedure for vascular resection and reconstruction includes exposure of the diseased vessel, temporary interruption of blood flow, resection of the diseased segment, vascular repair or anastomosis and restoration of blood flow. Adequate exposure, including the healthy portions on both the afferent and efferent sides of the diseased segment, facilitates subsequent steps in the procedure. Since the temporary interruption of blood flow could lead to ischemic and reperfusion injuries, it is necessary to take measures to protect organs that receive blood flow from diseased vessels. The basic principles in vascular suturing are single sutures through all layers and intima-to-intima approximation. Continuous simple sutures are often used for vascular repair and anastomoses. In the case of anastomoses between small arteries, however, interrupted simple sutures are preferred to prevent stenosis. Twisting, stenosis, and overstretch at the point of anastomosis are errors that result in failure of vascular reconstruction. The methods for overcoming size differences between anastomosed vessels should be understood. Topical heparinization is easy and a useful method to prevent the production of thrombus. Systemic administration of anticoagulants is not always needed.

Anastomosis, Surgical↗

Effect of long-term bedrest on lower leg muscle activation patterns during quiet standing.

It has been well known that balance instabilities after long-term exposure to microgravity (e.g., Anderson et al. 1986) or bedrest (BR) can be related to alterations and/or adaptations to postural control strategies. Little is known, however, how the reduced muscular activity affects the activation pattern of the lower limb muscles during quiet standing (QS). The purpose of this study was to investigate whether or not any changes in the lower limb muscle activation patterns during QS would occur after BR.

Adult↗

Hepatocyte growth factor induces differentiation of adult rat bone marrow cells into a hepatocyte lineage in vitro.

Bone marrow (BM) cells originally include alpha-fetoprotein (AFP)- and c-Met [a receptor for hepatocyte growth factor (HGF)]-expressing cells. In vitro treatment of BM cells with HGF induced albumin-expressing hepatocyte-like cells. Furthermore, those hepatocyte-like cells expressed cytokeratins 8 and 18, which are typically expressed in normal adult hepatocytes. These findings demonstrate that BM cells include AFP-expressing hepatic progenitor cells that can be differentiated into hepatocytes by HGF in culture, indicating that such cultures are useful resources for cell transplantation therapy for liver diseases.

Animals↗

Angiotensin II receptor antagonist, L-158,809, prevents intimal hyperplasia in dog grafted veins.

We investigated the levels of the angiotensin II-forming enzymes, chymase and angiotensin converting enzyme (ACE), in dog grafted veins, and studied the effect of an angiotensin II type 1 receptor antagonist, L-158,809, on vascular proliferation in the grafted veins. The right external jugular vein was grafted to the ipsilaterial carotid artery. In the group treated with L-158,809, the drug (10 mg/kg per day, p.o.) were administered orally from 7 days before the operation to 28 days after it, while the others were administrated placebo. In the placebo-treated group, the chymase activity in the grafted veins was increased about 10-fold and the ACE activity was doubled. The areas of intima and media were significantly increased in the grafted veins in the placebo-treated group. L-158,809 significantly reduced the intimal area of the grafted veins. An angiotensin II receptor antagonist, L-158,809, prevented the vascular proliferation in the grafted veins, and the development of the proliferation may depend on activation of local angiotensin II formation.

Angiotensin II↗

Allelic loss in human intrahepatic cholangiocarcinoma: correlation between chromosome 8p22 and tumor progression.

Intrahepatic cholangiocarcinoma (ICC) is the second most common malignant primary tumor of the liver in Japan. Despite progress in operative techniques and adjuvant therapy, the prognosis of ICC remains very poor. Therefore, it is important to investigate the mechanism of carcinogenesis and progression of ICC. We screened allelic losses at 6 loci, including that of novel tumor-suppressor gene FEZ1 on chromosome 8p, and at 5 microsatellite loci to define the association with tumor-suppressor genes (HNPCC, APC, RB1, p53, DCC) in tumors from 18 unrelated ICC patients by PCR-loss of heterozygosity (LOH) assay and correlated the alterations with clinicopathological parameters. As a result, 61.1% (11 of 18) of patients showed LOH at 1 of the loci at least, and microsatellite instability was observed in 16.7% (3 of 18). At locus D8S258, relatively frequent LOH was detected (17.6%) compared with other loci on chromosome 8p. Among the other 5 chromosomal arms tested, the highest frequency of LOH (23.5%) was observed at D17S153. Fifty percent of cases with the mass-forming + periductal infiltrating type were frequently detected by LOH at D8S258 compared to cases of the mass-forming or intraductal growth type. In conclusion, we show that 1 putative tumor-suppressor gene on 8p22 may relate to progression of ICC and suggest that the p53 tumor-suppressor gene may be associated with carcinogenesis of ICC.

Aged↗

CYFRA 21-1 determination in patients with esophageal squamous cell carcinoma: clinical utility for detection of recurrences.

BACKGROUND: While there are reports that CYFRA 21-1 is a useful tumor marker, to our knowledge the clinical utility of this marker to detect recurrences for squamous cell carcinoma of the esophagus has not been addressed. METHODS: By immunoradiometric assay, human serum levels of CYFRA 21-1, SCC antigen and CEA were measured in esophageal squamous cell carcinoma patients prior to their initial treatment. Monthly follow-ups of these tumor markers was done after surgery. RESULTS: The diagnostic sensitivity of CYFRA 21-1 was 43.9% (18 of 41), a value superior to that for SCC antigen (26.8%) and CEA (17.0%) (P < 0.05). The positive rates of CYFRA 21-1 increased with progression of the disease, 22.2% of pTNM Stage 0-IIA and 77.8% of pTNM Stage IIB/III (P = 0.013), whereas SCC antigen and CEA rates were not related to pTNM stage. Among 13 patients with clinical evidence of a recurrence, 76.9% (10 of 13) exhibited an increase in CYFRA 21-1, and this increase was evident before clinical detection of the recurrence in 9 of these 13 patients (69.2%). Consequently, postoperative elevations of serum CYFRA 21-1 levels were indicative of a tumor recurrence 1-13 months before acquisition of clinical and radiological data. CONCLUSIONS: The assay of CYFRA 21-1 is useful not only for diagnosis but also for close monitoring of patients with esophageal squamous cell carcinoma.

Antigens, Neoplasm↗

The biosynthesis of hepatic cholesterol esters and triglycerides is impaired in mice with a disruption of the gene for stearoyl-CoA desaturase 1.

Stearoyl-CoA desaturase (SCD) is a microsomal enzyme required for the biosynthesis of oleate and palmitoleate, which are the major monounsaturated fatty acids of membrane phospholipids, triglycerides, and cholesterol esters. Two well characterized isoforms of SCD, SCD1 and SCD2, exist in the mouse. Most mouse tissues express SCD1 and 2 with the exception of the liver, which expresses mainly the SCD1 isoform. We found that asebia mice homozygous for a natural mutation of the gene for SCD1 (SCD-/-) are deficient in hepatic cholesterol esters and triglycerides despite the presence of normal activities of acyl-CoA:cholesterol acyltransferase and glycerol phosphate acyltransferase, the enzymes responsible for cholesterol ester and triglyceride synthesis, respectively, in the liver of these mice. Feeding diets supplemented with triolein or tripalmitolein to the SCD-/- mice resulted in an increase in the levels of 16:1 and 18:1 in the liver but failed to restore the 18:1 and 16:1 levels of the cholesterol ester and triglycerides to the levels found in normal mice. The SCD-/- mouse had very low levels of triglycerides in the VLDL and LDL lipoprotein fractions compared with the normal animal. Transient transfection of an SCD1 expression vector into Chinese hamster ovary cells resulted in increased SCD activity and esterification of cholesterol to cholesterol esters. Taken together, our observations demonstrate that the oleoyl-CoA and palmitoleyl-CoA produced by SCD1 are necessary to synthesize enough cholesterol esters and triglycerides in the liver and suggest that regulation of SCD1 activity plays an important role in mechanisms of cellular cholesterol homeostasis.

Animals↗

New induction of leukotriene A(4) hydrolase by interleukin-4 and interleukin-13 in human polymorphonuclear leukocytes.

Interleukin (IL)-4, IL-10, and IL-13, Th2 cell-derived cytokines, play major roles in the pathophysiology of allergic diseases. These cytokines up-regulate or down-regulate the production of arachidonic acid metabolites. In this study, we have investigated the effect of IL-4, IL-10, IL-13, and other cytokines on A23187-stimulated synthesis of leukotriene (LT) B(4) in human polymorphonuclear leukocytes (PMNs). Production of LTB(4) was measured by specific radioimmunoassay and high performance liquid chromatography. Messenger RNA (mRNA) expression of cytosolic phospholipase A(2) (cPLA(2)), 5-lipoxygenase (5-LO), and LTA(4) hydrolase, which were involved in the synthesis of LTB(4), was determined by reverse transcription-polymerase chain reaction and Northern blot analysis. Protein synthesis of their enzymes was determined by Western blot analysis. IL-4 and IL-13 enhanced A23187-stimulated LTB(4) synthesis and increased mRNA expression and protein synthesis of LTA(4) hydrolase, but not those of cPLA(2) or 5-LO. These results indicate that IL-4 and IL-13 transcriptionally or post-transcriptionally up-regulate the synthesis of LTB(4), a potent chemotactic factor to PMNs, at the enzyme level of LTA(4) hydrolase, and this up-regulation mechanism may participate in the development of allergic inflammation. (Blood. 2000;96:601-609)

Arachidonate 5-Lipoxygenase↗

Relationship between contact inhibition and intranuclear S100C of normal human fibroblasts.

Many lines of evidence indicate that neoplastic transformation of cells occurs by a multistep process. For neoplastic transformation of normal human cells, they must be first immortalized and then be converted into neoplastic cells. It is well known that the immortalization is a critical step for the neoplastic transformation of cells and that the immortal phenotype is recessive. Thus, we investigated proteins downregulated in immortalized cells by two-dimensional gel electrophoresis. As a result, S100C, a Ca(2+)-binding protein, was dramatically downregulated in immortalized human fibroblasts compared with their normal counterparts. When the cells reached confluence, S100C was phosphorylated on threonine 10. Then the phosphorylated S100C moved to and accumulated in the nuclei of normal cells, whereas in immortalized cells it was not phosphorylated and remained in the cytoplasm. Microinjection of the anti-S100C antibody into normal confluent quiescent cells induced DNA synthesis. Furthermore, when exogenous S100C was compelled to localize in the nuclei of HeLa cells, their DNA synthesis was remarkably inhibited with increase in cyclin-dependent kinase inhibitors such as p16(Ink4a) and p21(Waf1). These data indicate the possible involvement of nuclear S100C in the contact inhibition of cell growth.

Amino Acid Sequence↗

MTABC3, a novel mitochondrial ATP-binding cassette protein involved in iron homeostasis.

Atm1p, a mitochondrial half-type ATP-binding cassette (ABC) protein in Saccharomyces cerevisiae, transports a precursor of the iron-sulfur (Fe/S) cluster from mitochondria to the cytosol. We have identified a novel half-type human ABC protein, designating it MTABC3 (mammalian mitochondrial ABC protein 3). MTABC3 mRNA is ubiquitously expressed in all of the rat and human tissues examined. MTABC3 protein is shown to be present in the mitochondria, as assessed by immunoblot analysis and confocal microscopic analysis of subcellular fractions of Chinese hamster ovary cells stably expressing MTABC3. Accumulation of iron in the mitochondria, mitochondrial DNA damage, and respiratory dysfunction in the yeast ATM1 mutant strain (atm1-1 mutant cells) were almost fully reversed by expressing MTABC3 in these mutant cells. These results indicate that MTABC3 is a novel ortholog of the yeast and suggest an important role in mitochondrial function. Interestingly, the human MTABC3 gene has been mapped to chromosome 2q36, a region within the candidate locus for lethal neonatal metabolic syndrome, a disorder of the mitochondrial function associated with iron metabolism, indicating that MTABC3 is a candidate gene for this disorder.

ATP-Binding Cassette Transporters↗

p53 polymorphism in human papillomavirus-associated esophageal cancer.

Human papillomavirus type 16/18 (HPV-16/18) is implicated in the pathogenesis of squamous cell carcinoma (SCC) of the cervix and esophagus. The arginine allele at codon 72 of p53 was found to be more susceptible to degradation by HPV E6 protein than is the proline allele in vivo, thus resulting in a high frequency of cervical SCC in individuals homozygous for arginine at the codon. There are controversial results from several clinical studies of cervical SCC. In the present study, encoding regions of p53 codon 72 and HPV-16/18 E6 were directly sequenced, using pairs of primary esophageal SCC tissue and corresponding normal mucosa, which were from 75 patients (Japanese, n = 38; Chinese, n = 37). The arginine allele alone was detected in 70.6% (12 of 17) of HPV-positive cases but only in 43.1% (25 of 58) of HPV-negative cases (P < 0.05). In contrast, such a significant correlation between p53 polymorphism and HPV infection was not evident in corresponding normal mucosae. Because our findings between tumor specimens and the normal mucosae differed, we suggest that the frequent loss of proline allele in HPV-associated carcinogenesis of the esophagus major plays some role. The particular type of p53 polymorphism may indicate a potential candidate for HPV-associated SCC.

Alleles↗