Biomedical subjects

T Kitada

Publications and source records attributed to T Kitada.

At least 19 recordsLinked to original sources

PubMed2005

Five-year survival of patients with hepatocellular carcinoma treated with laparoscopic microwave coagulation therapy.

BACKGROUND AND STUDY AIM: Hepatocellular carcinomas (HCCs) that are located near the liver surface are difficult to treat with percutaneous locoregional therapies, so we have performed laparoscopic microwave coagulation therapy (LMCT) for these HCCs. We assessed the long-term survival of patients with HCCs treated with LMCT, the factors related to their survival, and the rates and causes of local and distant recurrences. PATIENTS AND METHODS: Participants were 68 patients with HCC treated in the past 8 years with LMCT under local or general anesthesia. LMCT was done using microwave electrodes with tips ranging from 15 to 45 mm in length; the effectiveness of LMCT was confirmed using contrast-enhanced computed tomography (CT) within 2 weeks of the LMCT procedure while patients were still in hospital, and within 1-3 months after the procedure in an outpatient setting; and the follow-up study was performed periodically by CT, ultrasonography, or magnetic resonance imaging (MRI) in addition to estimation of alpha fetoprotein. Factors contributing to survival were analyzed statistically. RESULTS: The mean lengths of the major and minor axes of the 71 HCC nodules in 68 patients were 20 mm and 18 mm, respectively, and the mean lengths of the major and minor axes of the coagulated areas were 43 mm and 29 mm, respectively. At dynamic CT after the LMCT procedure, treatment in 62 of the 68 patients (91%) was judged to have been completely effective; the remaining six patients underwent additional therapy while still in hospital. Eight of the 68 patients (12%) had local recurrences, 39 of them (57%) had distant recurrences, and 21 of them (31%) had no recurrence up to December 31, 2003. A total of 14 patients (21%) died during the 16-56 months after LMCT. When the survival rate was assessed for all patients treated with LMCT, 1-year survival was 97 %, 3-year survival was 81%, and 5-year survival was 43%. Whether the therapy was for primary or secondary HCC strongly influenced survival. CONCLUSIONS: LMCT is a useful modality in clinical practice for treatment of HCC nodules located near the liver surface, and it can be safely performed, in its entirety, under direct visual guidance.

Aged↗

PubMed2003

Pathological significance of oxidative cellular damage in human alcoholic liver disease.

AIMS: To investigate the pathological significance of oxidative stress-induced lipid peroxidation and oxidative DNA damage in alcoholic liver disease. METHODS AND RESULTS: Hepatic expression of 4-hydroxy-2'-nonenal (HNE) adducts and 8-hydroxydeoxyguanosine (8-OHdG) as reliable markers of lipid peroxidation and oxidative DNA damage, respectively, was analysed immunohistochemically and compared with histological findings in alcoholic liver disease. While no HNE adducts were observed in control livers, HNE adducts were frequently (37 of 40 cases, 92.5%) detected in alcoholic liver disease. The localization of HNE adducts was the cytoplasm of hepatocytes and sinusoidal cells in zone 3. As for 8-OHdG, 29 of 40 cases (72.5%) with alcoholic liver disease exhibited positive immunolabelling for 8-OHdG, while 8-OHdG expression was not evident in control livers. The nuclear expression of 8-OHdG was mainly detected in the hepatocytes within the areas of active inflammation. Among histological parameters, the grade of necro-inflammation activity as well as the presence of Mallory bodies were significantly associated with the expression of HNE adducts and 8-OHdG. In addition, the severity of steatosis also correlated with HNE adduct expression. CONCLUSIONS: Lipid peroxidation and oxidative DNA damage occur widely and may be associated with certain pathological features in human alcoholic liver disease.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2003

Clinicopathological significance of hypoxia-inducible factor-1alpha expression in human pancreatic carcinoma.

AIMS: The transcription factor hypoxia-inducible factor-1alpha (HIF-1alpha) plays a key role in the cellular adaptation to hypoxia and the activation of several genes that have been implicated in tumour growth. The aim of this study was to investigate the clinicopathological significance of HIF-1alpha expression in pancreatic carcinoma. METHODS AND RESULTS: We investigated HIF-1alpha expression immunohistochemically in pancreatic carcinoma tissues and regional lymph node metastasis. In cases of pancreatic ductal carcinoma, the relationship between HIF-1alpha expression and various clinicopathological parameters including cellular proliferation, apoptosis, and microvessel density, was also examined. Over-expression of HIF-1alpha was frequently (29 of 49 cases, 59.2%) detected in pancreatic carcinoma and regional lymph node metastasis (19 of 25 cases, 76.0%), whereas HIF-1alpha expression was almost absent in non-cancerous pancreatic tissues. HIF-1alpha expression was significantly associated with tumour size (P = 0.023) and advanced TNM stage (stage I/II versus stage III, P = 0.039; stage I/II versus stage IV, P = 0.027). Moreover, HIF-1alpha expression positively correlated with cellular proliferation (P = 0.024) and microvessel density/neo-angiogenesis (P = 0.038), but not with apoptosis. CONCLUSIONS: HIF-1alpha may play a critical role in the progression of pancreatic carcinoma.

Adenocarcinoma, Papillary↗

PubMed2002

Immunohistochemical detection of 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, in human chronic cholecystitis.

AIMS: Recent studies suggest that oxidative DNA damage induced during chronic inflammation may play a role in carcinogenesis in some organs. Although gallbladder carcinomas are frequently observed with a background of chronic cholecystitis, little is known about oxidative DNA damage in chronic cholecystitis. The aims of this study were to investigate the expression of 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, in normal and chronically inflamed human gallbladder mucosa and compare its expression with clinicopathological findings. METHODS AND RESULTS: 8-OHdG expression was immunohistochemically examined using a monoclonal antibody against 8-OHdG in human gallbladder specimens. In normal gallbladder (n=5), no 8-OHdG expression was observed. In contrast, nuclear expression of 8-OHdG was detected in 28 of 31cases (90.3%) in gallbladder epithelial cells with chronic cholecystitis. The positive cells were predominantly observed in the areas of active inflammation with prominent cell infiltration. Quantitative analysis revealed that the number of 8-OHdG+ cells (labelling index) significantly (rs=0.671, P < 0.05) correlated with the degree of the activity of mucosal inflammation, while gender, age, and the presence of gallstones did not influence the index. CONCLUSIONS: Oxidative DNA damage is common in chronic cholecystitis, suggesting a possible link between chronic inflammation and gallbladder carcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

XAFS study on the sulfidation mechanisms of Co-Mo catalysts supported on activated carbon and alumina: effect of complexing agent.

The effect of nitrilotriacetic acid (NTA) as a complexing agent on the sulfidation mechanisms of Co-Mo catalysts supported on activated carbon and alumina was examined by the XAFS technique. The XAFS results revealed that NTA interacted with Co atoms and formed the Co-NTA interaction, while it showed almost no influence on the local structures around Mo atoms. The Co-NTA interaction suppressed the aggregation of cobalt atoms and the interaction between cobalt and alumina during sulfiding, and consequently promoted the formation of the Co-Mo-S phase.

Journal Article↗

PubMed2001

The addition of bisecting N-acetylglucosamine residues to E-cadherin down-regulates the tyrosine phosphorylation of beta-catenin.

The enzyme GnT-III (beta 1,4-N-acetylglucosaminyltransferase III) catalyzes the addition of a bisecting N-acetylglucosamine (GlcNAc) residue on glycoproteins. Our previous study described that the transfection of GnT-lll into mouse melanoma cells results in the enhanced expression of E-cadherin, which in turn leads to the suppression of lung metastasis. It has recently been proposed that the phosphorylation of a tyrosine residue of beta-catenin is associated with cell migration. The present study reports on the importance of bisecting GlcNAc residues by GnT-lll on tyrosine phosphorylation of beta-catenin using three types of cancer cell lines. An addition of bisecting GlcNAc residues to E-cadherin leads to an alteration in cell morphology and the localization of beta-catenin after epidermal growth factor stimulation. These changes are the result of a down-regulation in the tyrosine phosphorylation of beta-catenin. In addition, tyrosine phosphorylation of beta-catenin by transfection of constitutively active c-src was suppressed in GnT-III transfectants as well as in the case of epidermal growth factor stimulation. Treatment with tunicamycin abolished any differences in beta-catenin phosphorylation for the mock vis à vis the GnT-lll transfectants. Thus, the addition of a specific N-glycan structure, the bisecting GlcNAc to E-cadherin-beta-catenin complex, down-regulates the intracellular signaling pathway, suggesting its implication in cell motility and the suppression of cancer metastasis.

Acetylglucosamine↗

PubMed2001

In situ detection of oxidative DNA damage, 8-hydroxydeoxyguanosine, in chronic human liver disease.

BACKGROUND/AIMS: 8-Hydroxydeoxyguanosine (8-OHdG) is a promutagenic DNA lesion produced by oxygen radicals and is recognized as a useful marker in estimating DNA damage induced by oxidative stress. METHODS: Hepatic expression of 8-OHdG was immunohistochemically investigated in control and diseased human livers. RESULTS: While no positive immunolabeling for 8-OHdG was observed in control livers, 8-OHdG was widely evident in diseased livers. Nuclear expression of 8-OHdG in the hepatocytes and bile duct cells were found in various forms of chronic hepatitis. 8-OHdG-positive hepatocytes were especially abundant in the periportal area with piecemeal necrosis and prominent cell infiltration. The number of positive hepatocytes significantly increased with the progression of severity of chronic hepatitis activity (r(s)=0.68, P<0.05). In alcoholic liver disease, nuclear expression of 8-OHdG was detected in the hepatocytes in the area of alcoholic hepatitis. Regarding primary biliary cirrhosis, 8-OHdG was preferentially detected in the nuclei of injured bile ducts (11 of 12 cases, 91.7%) and occasionally (2 of 12 cases, 16.7%) in the nuclei of hepatocytes around the bile duct lesions. CONCLUSIONS: These results indicate that oxidative DNA damage is common in various forms of chronic liver disease suggesting a possible link between chronic inflammation and hepatocarcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

Cardiac tamponade caused by spontaneous rupture of mediastinal lymph node metastasis of hepatocellular carcinoma.

Rupture of a hepatocellular carcinoma (HCC) is a well-known cause of death in patients with HCC. This report describes a rare case of HCC presenting as cardiac tamponade caused by a spontaneous rupture of mediastinal lymph node metastasis into the pericardial space. A transcatheter arterial embolization (TAE) of internal thoracic artery successfully controlled the bleeding, and the patient was rescued from cardiac tamponade. Although there was no rebleeding, the patient died from liver failure 2 months later. An autopsy revealed a poorly differentiated HCC in the liver, lung and mediastinal lymph nodes.

Carcinoma, Hepatocellular↗

PubMed2001

Developmental changes in the expression of parkin and UbcR7, a parkin-interacting and ubiquitin-conjugating enzyme, in rat brain.

Parkin is a product of the Park2 gene the mutation of which causes autosomal recessive juvenile parkinsonism (AR-JP) characterized by selective dopaminergic neuronal death and absence of Lewy bodies. Recently we found that parkin is directly linked to the ubiquitin (Ub)-proteasome pathway as a Ub-protein ligase (E3) collaborating with a Ub-conjugating enzyme (E2) UbcH7. Here we analysed by in situ hybridization the expression of mRNAs for parkin and UbcR7 (rat orthologue of human UbcH7) in the developing rat brain. Parkin mRNA increased in parallel with neuronal maturation, but was unevenly distributed in various brain regions after four postnatal days. The expression pattern of the UbcR7 mRNA was almost identical to that of the parkin mRNA in all cases examined. Both parkin and UbcR7 mRNAs were distributed in neurones but not glial cells. Our findings indicate that parkin is expressed not only in the substantia nigra, but also uniformly in various brain regions in a development-dependent manner. Co-expression of UbcR7 with parkin suggests that UbcR7 may interact with parkin in vivo for ubiquitination of yet unidentified target protein(s).

Animals↗

PubMed2001

Familial Parkinson's disease. Alpha-synuclein and parkin.

We have reviewed recent progress in establishing the function of alpha-synuclein and parkin in relation to nigral degeneration in autosomal dominant and autosomal recessive PD. Mutations of alpha-synuclein (Ala53Thr and Ala30Pro) cause a form of autosomal dominant PD with early onset. Parkin is a novel protein expressed in the cytoplasm, including the terminal regions and Golgi apparatus. Mutations of parkin cause a form of autosomal recessive young-onset PD (ARJP). Both proteins appear to be associated with fast axonal transport. In addition, in sporadic PD, normal alpha-synuclein shows an increased tendency to self-aggregate. Thus, altered axonal transport of presynaptic proteins appears to play a crucial role in neurodegeneration in PD.

Humans↗

PubMed2000

PARKIN as a pathogenic gene for autosomal recessive juvenile parkinsonism.

Parkinson's disease is a common neurodegenerative disease with complex clinical features. Recently, we idenfied a novel gene named Parkin to be responsible for the pathogenesis of autosomal recessive juvenile parkinsonism (AR-JP). Various mutations were found in AR-JP patients of Japanese and other ethnic origins, providing a definitive evidence for the Parkin to be a causative gene for AR-JP. The predicted structure of Parkin protein and its mutation provide important clues for studying the functional role of the Parkin protein in leading to selective degeneration of nigral neurons in the brains of AR-JP patients.

Amino Acid Motifs↗

PubMed2000

Molecular cloning, gene expression, and identification of a splicing variant of the mouse parkin gene.

We have isolated mouse cDNA clones that are homologous to human Parkin gene, which was recently found to be responsible for the pathogenesis of autosomal recessive juvenile parkinsonism (AR-JP). One of these cDNA clones had the 1,392-bp open reading frame encoding a protein of 464 amino acids with presumed molecular weight of 51,615. The amino acid sequence of mouse parkin protein exhibits 83.2% identity to human Parkin protein, including the ubiquitin-like domain at the N-terminus (identity = 89.5%) and the RING finger-like domain at the C-terminus (identity = 90.6%). Two other clones had the 783-bp open reading frame encoding a truncated protein of 261 amino acids without RING finger-like domain. It was proved to be a novel splicing variant by 3'-RACE method. Northern blot analysis revealed that mouse parkin gene is expressed in various tissues including brain, heart, liver, skeletal muscle, kidney, and testis. It is notable that mouse parkin gene expression appears evident in 15th day mouse embryo and increases toward the later stage of development. These mouse parkin cDNA clones will be useful for elucidating the essential physiological function of parkin protein in mammals.

Alternative Splicing↗

PubMed2000

Progress in the clinical and molecular genetics of familial parkinsonism.

Parkinson's disease (PD) is a neurodegenerative disease with clinical features resulting from deficiency of dopamine in the nigrostriatal system. Most PD cases are sporadic and the primary cause of the disease is still unknown. Recently, familial PD and parkinsonism have received much attention because these forms of the disease might provide clues to the genetic risk factors involved in the pathogenesis of idiopathic PD. To date, two causative genes, alpha-synuclein and the parkin gene, have been identified. alpha-Synuclein is involved in the pathogenesis of an autosomal dominant form of PD and constitutes a major component of the Lewy body, which is a pathological hallmark of idiopathic PD. In addition, mutations in the parkin gene have been identified as the cause of autosomal recessive juvenile parkinsonism (AR-JP). AR-JP manifests itself as a highly selective degeneration of the substantia nigra and the locus coeruleus, but without Lewy body formation. In addition to these two genes, four chromosomal loci have been linked to other forms of familial PD. Furthermore, there are a number of other pedigrees of familial PD in which linkage to known genetic loci has been excluded. Molecular cloning of these disease genes and elucidation of the function of their gene products will greatly contribute to our understanding of the pathogenesis of idiopathic PD.

Amino Acid Sequence↗

PubMed2000

Clinicopathological characterization of prion: a novel marker of activated human hepatic stellate cells.

BACKGROUND/AIMS: We recently demonstrated prion as a new marker for hepatic stellate cell activation in rats. Here, we have examined prion expression in normal and diseased human livers. METHODS: Prion expression was examined at protein level by immunohistochemistry and at mRNA level by in situ hybridization. RESULTS: While normal livers were negative for prion, all liver specimens but one from patients with chronic liver disease were positively stained. In chronic hepatitis, prion protein expression was found not only in the sinusoidal lining cells within the lobules but also in mesenchymal cells in expanded portal tracts. In alcoholic liver disease, prion-positive cells were found mainly in the areas of alcoholic hepatitis. Immunoelectronmicroscopy revealed that prion-positive cells were activated stellate cells. In situ hybridization demonstrated that the distribution of prion mRNA is similar to that of prion protein. In chronic hepatitis, the number of prion-positive cells correlated with the grade of activity but not with the stage of fibrosis. In alcoholic liver disease, levels of prion protein expression were significantly increased in the presence of alcoholic hepatitis. CONCLUSION: Prion as a novel marker of activated stellate cells correlates well with disease activity in human chronic liver diseases.

Biomarkers↗

PubMed2000

Autosomal recessive juvenile parkinsonism: a key to understanding nigral degeneration in sporadic Parkinson's disease.

The contribution of genetic factors to the pathogenesis of Parkinson's disease (PD) is supported by the demonstration of the high concordance in twins studies using positron emission tomography (PET), the increased risk among relatives of PD patients in case-control and family studies, and the existence of familial PD and parkinsonism by single gene defect. Recently several genes have been mapped and/or identified. Alpha-synuclein is involved in a rare dominant form of familial PD with dopa-responsive parkinsonism features and Lewy body-positive pathology. In contrast, parkin is responsible for the autosomal recessive form (AR-JP) of early onset PD with Lewy body-negative pathology. The clinical features of this form include early onset (in the 20s), levodopa-responsive parkinsonism, diurnal fluctuation, and slow progression of the disease. Parkin consists of 12 exons and the estimated size is over 1.5 Mb. To date, variable mutations such as deletions or point mutations resulting in missense and nonsense changes have been reported in AR-JP patients. In addition, the localization of parkin indicates that parkin may be involved in the axonal transport system. More recently we have found that parkin interacts with the ubiquitin-conjugating enzyme E2 and is functionally linked to the Ub-proteasome pathway as a ubiquitin ligase, E3. These findings fit the characteristics of a lack of Lewy bodies (these are cytoplasmic inclusions that are considered to be a pathological hallmark). Our findings should enhance the exploration of the mechanisms of neuronal death in PD as well as other neurodegenerative disorders of which variable inclusion bodies are observed.

Chromosomes, Human, Pair 6↗

PubMed2000

Laparoscopic microwave coagulation therapy for hepatocellular carcinoma.

BACKGROUND AND STUDY AIMS: Several different effective forms of treatment are available, singly or in combination, for patients with hepatocellular carcinoma (HCC). These include surgical resection, transcatheter arterial embolization, percutaneous ethanol injection, and percutaneous microwave coagulation therapy. In this study, we carried out laparoscopic microwave coagulation therapy (LMCT), using laparoscopic microwave electrodes to treat HCC. PATIENTS AND METHODS: Under local anesthesia, 24 patients with HCCs located on or near the liver surface underwent LMCT under direct laparoscopic vision, with ultrasound guidance. LMCT was performed using microwave electrodes with tips ranging from 15-45 mm in length, and the effectiveness of the treatment was confirmed using contrast-enhanced computed tomography (CT) within two weeks of the LMCT procedure. RESULTS: The mean longest axis of the 26 HCC nodules in 24 patients was 20 mm, and that of the coagulated areas including the nodules was 40 mm, with additional therapy being required in two patients. Complete efficacy of the treatment was observed in 21 patients (87.5%), but local recurrences were seen in three of them one year after LMCT. The three-year survival rate was 92%, but the number of patients included in the study was small. Hemostasis was complete, but mild pneumothorax occurred in three patients. CONCLUSIONS: LMCT under local anesthesia is a minimally invasive and effective therapy when carried out on a single occasion to treat HCCs located near the liver surface, and it can be safely performed under direct visual guidance.

Aged↗

PubMed2000

Outcomes of dysplastic nodules in human cirrhotic liver: a clinicopathological study.

The number of dysplastic nodules detected clinically has increased since patients with hepatitis virus-associated cirrhosis, who are at increased risk for hepatocellular carcinoma (HCC), began to undergo regular cancer surveillance. Although it is potentially important to determine which type(s) of nodule may be prone to progress to HCC, outcomes of dysplastic nodules have not been fully investigated. This prompted us to examine the outcomes of dysplastic nodules in cirrhotic patients clinicopathologically. We studied 33 dysplastic nodules of <20 mm in maximum diameter, diagnosed by fine needle aspiration biopsy under ultrasonography (US). These nodules were clinically followed, mainly by US examination, for up to 70 months. When the nodules enlarged or exhibited changes on US, they were histologically reexamined by second biopsy. Surprisingly, 15 of the 33 nodules (45.5%) disappeared, 14 nodules (42.4%) remained unchanged, and only 4 nodules (12.1%) progressed to HCC. The latter 4 nodules were all hyperechoic on US and were composed of clear cells with fatty change or small cells with increased nuclear density, and in all 4 patients serum was positive for hepatitis C virus antibody. Univariate analyses revealed that, although not significant, the hyperechoic nodules or nodules with small cell change showed a higher HCC progression rate in comparison with the hypoechoic nodules or the nodules without small cell change. In summary, most of the dysplastic nodules we followed disappeared or remained unchanged, but some progressed to HCC. Hyperechoic nodules in patients with hepatitis C virus-associated cirrhosis, which show small cell change with increased nuclear density, may be prone to progress to HCC.

Adult↗

PubMed2000

[Molecular pathogenesis of familial Parkinson's disease].

Parkinson's disease is thought to be caused by an interaction of polygenic predisposition with environmental factors. In contrast, familial parkinsonism is caused by a single gene mutation. Four causative genes, i.e. alpha-synuclein, tau, UCH-L1 and parkin gene, have been already identified during the last three years. Their functions are being investigated from the points of over-production of abnormal proteins or abnormal proteolysis caused by them. Investigating and characterizing these causative genes may help us to explore the molecular mechanism of nigral neuronal cell death in sporadic type as well. In this paper, we review recent progress in molecular structures, pathogenesis, and animal models for these four genes.

Animals↗