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Y Ko

Publications and source records attributed to Y Ko.

At least 55 records · Page 3Linked to original sources
PubMed2000

NAD(P)H quinone oxidoreductase 1 codon 609 polymorphism and its association to colorectal cancer.

The present study used a rapid and single-step method for genotyping of NAD(P)H quinone oxidoreductase (NQO1) codon 609 polymorphism using real-time polymerase chain reaction (PCR)-analysis and subsequent melting curve analysis for the analysis of allelic distribution of NQO1. The design was a case control study of 323 Caucasians with colorectal cancer and 205 healthy controls. There was no difference in the frequencies of the mutated NQO1 allele (NQO1*2): 0.190 for control individuals and 0.195 for cancer patients, respectively (P=0.947). When this allelic distribution was further compared between non-smoking and smoking colorectal cancer patients, it appeared that the frequency of the wild-type allele NQO1*1 was higher in the smoking than in the non-smoking group [Odds ratio (OR), 0.434; 95% confidence interval (CI), 0.13-1.42]. This observation may suggest a protective role of the NQO1 wild-type allele in colon cancer susceptibility of individuals exposed to NQO1-inducing chemicals.

Adenocarcinoma↗
PubMed2000

Eukaryotic initiation factor 3 p110 mRNA is overexpressed in testicular seminomas.

Testicular germ cell tumors are important neoplasms and seminoma accounts for 40 to 50% of these tumors. Little is known concerning the molecular events underlying the development of these malignancies. In the present study we used a modified differential display approach to compare gene expression between seminoma and normal testicular parenchyma, both of which are mixed tissues. We first analyzed mRNA (cDNA) expression by differential display and then directly used differentially expressed cDNAs for the synthesis of radiolabeled riboprobes to attribute differential expression to specific cell types in tissue sections by in situ hybridization. Using this approach along with real-time quantitative reverse transcriptase-polymerase chain reaction analysis we found an overexpression of eukaryotic initiation factor 3 p110 mRNA (EIF3S8) in seminoma cells compared to normal germ cells of testicular tubules. The elF3-p110 subunit may promote seminoma development by generally increasing translation leading to enhanced cellular growth and division rates.

Adult↗
PubMed2000

Expression of tenascin-C in astrocytic tumors: its relevance to proliferation and angiogenesis.

BACKGROUND: The expression and distribution of the extracellular matrix protein tenascin-C (TN-C) may be enhanced in human astrocytomas. The purpose of this study is to evaluate the expression of TN-C according to histological malignancy of tumor cells and its relevance to neoplastic angiogenesis in human astrocytic tumors. METHODS: Between 1994 and 1998, 52 astrocytic tumor specimens including 4 pilocytic astrocytomas, 13 astrocytomas, 3 anaplastic astrocytomas, and 32 glioblastomas were used in this study. A retrospective analysis was performed to evaluate a statistical correlation between TN-C expression and proliferative indices. We characterized the expression of TN-C in neoplastic vessels, around individual tumor cells as a tumor network, and in tumor cells by immunohistochemistry using antibodies against human TN-C. The proliferative indices were also investigated by immunostaining with the MIB-1 antibody against the Ki-67 proliferation antigen. RESULTS: TN-C immunoreactivity was found to be enhanced in tumor vessels and tumor networks of high-grade astrocytic tumors. The vascular TN-C deposition was greater in high-grade than in low-grade astrocytic tumors (p < 0.05). Its expression was the most intense in glioblastomas. Proliferation indices increased with tumor grade and MIB-1 labeling index (LI) was highest in glioblastomas. Moreover, expression of TN-C in tumor vessels was correlated with proliferative indices. CONCLUSIONS: Our data show that TN-C in human astrocytic tumors may be identified as a factor contributing to malignant progression. And also, enhanced expression of TN-C in tumor vessels having a high proliferative index indicates that TN-C could be involved in neoplastic angiogenesis.

Adolescent↗
PubMed2000

Chronic liver disease in heterozygous alpha1-antitrypsin deficiency PiZ.

BACKGROUND/AIMS: The contribution of the heterozygous state PiZ of alpha1-antitrypsin deficiency (AATD) to the pathogenesis of chronic liver disease is debated. We analyzed whether patients with this genetic defect carrying a single PiZ gene are at increased risk for developing chronic liver disease. METHODS: 1847 consecutive biopsy cases and 1030 autopsy cases of Caucasian adults were screened immunohistochemically for PiZ deposits. The zygosity status was analyzed by single-strand conformational polymorphism (SSCP) and by sequencing DNA extracted from paraffin-embedded tissue. RESULTS: All analyzed biopsy cases were heterozygous for the PiZ mutation. The biopsy group revealed a significantly higher rate of PiZ-positive cases (3.4%) than the autopsy group (1.8%) (p=0.019). PiZ deposits ranged from scarce granules to extensive globular inclusions as in homozygous AATD of PiZ type. The extent of PiZ deposits correlated well with the inflammatory activity and stage of fibrosis. Cirrhotic livers contained globular PiZ deposits significantly more often than the biopsies with minor fibrosis. PiZ-positive biopsies from patients without concurrent liver disease (n= 26) revealed only minor fibrosis in the age group between 20 and 39 years, but significantly more severe fibrosis and significantly more PiZ deposits in the older age groups. Biopsies with concurrent liver disease (n=28) presented with significantly more severe inflammation and fibrosis, and more PiZ deposits than the cases without concurrent liver disease. CONCLUSIONS: Patients with heterozygous AATD of PiZ type bear an increased risk for chronic liver disease. If at all, this genetic defect will become clinically relevant only in middle-aged or old adults. It rarely causes liver cirrhosis even without concurrent liver disease. It can aggravate or can be aggravated by advanced coexistent chronic liver diseases. PiZ immunohistochemistry is an easy, highly specific method to detect this metabolic defect on liver biopsies.

Adult↗
PubMed2000

Detection of alpha-1-antitrypsin PiZ individuals by SSCP and DNA sequencing in formalin-fixed and paraffin-embedded tissue: a comparison with immunohistochemical analysis.

BACKGROUND/AIM: The role of alpha-1-antitrypsin (AAT) deficiency in the development of cirrhosis and carcinoma of the liver can be investigated from the analysis of archival biopsy specimens. Immunohistochemistry can visualize the storage of defective protease inhibitor (Pi) variant Z, but does not allow differentation between homozygous and heterozygous patients. The aim of the study was to establish a method for the detection of the PiZ mutation on the gene level. METHODS: Liver biopsy and autopsy samples in which AAT deficiency was detected immunohistochemically by a monoclonal PiZ-antibody were analyzed by single-strand conformational polymorphism (SSCP) to reliably determine hetero- and homozygote carrier state in the absence of blood samples and to confirm the histological diagnosis. The accuracy of SSCP was verified by direct DNA sequencing. RESULTS: Tissue slices (>0.8 cm2) from 29 consecutive cases with immunohistochemically detected PiZ depositions and from ten PiZ-negative control cases were provided for extraction and amplification of DNA. In comparison to wild-type sequence of AAT exon V, all 29 cases showed band shifts on SSCP analysis, with a heterozygous pattern in 28 patients and a homozygous pattern in one patient. DNA sequence analysis revealed the same single-base mutation at position 342 of AAT exon V. CONCLUSIONS: SSCP analysis proved a sensitive and specific technique for the detection of the PiZ mutation at the gene level, which allowed unequivocal differentiation between heterozygous and homozygous PiZ status from paraffin-embedded archival tissue specimens. Besides a use in diagnostic pathology, this technique could be valuable for prenatal diagnosis and population screening purposes.

Base Sequence↗
PubMed2000

Cholera toxin treatment of vascular smooth muscle cells decreases smooth muscle alpha-actin content and abolishes the platelet-derived growth factor-BB-stimulated DNA synthesis.

The second messenger cyclic AMP regulates diverse biological processes such as cell morphology and cell growth. We examined the role of the second messenger cyclic AMP on rat aortic vascular smooth muscle cell (VSMC) morphology and the intracellular transduction pathway mediated by platelet-derived growth factor beta-receptor (PDGF-Rbeta). The effect of PDGF-BB on VSMCs growth was assessed by [(3)H]-thymidine incorporation. Tyrosine phosphorylation of PDGF-Rbeta, PLC-gamma1, ERK1 and ERK2, p125(FAK) and paxillin as well as Sm alpha-actin was examined by the chemiluminescence Western blotting method. Actin mRNA level was quantitated by Northern blotting. Visualization of Sm alpha-actin filaments, paxillin and PDGF-Rbeta was performed by immunfluorescence microscopy. Cholera toxin (CTX; 10 nM) treatment lead to a large and sustained increase in the cyclic AMP concentration after 2 h which correlated with change of VSMC morphology including complete disruption of the Sm alpha-actin filament array and loss of focal adhesions. Treatment of VSMCs with CTX did not influence tyrosine phosphorylation of p125(FAK) and paxillin but decreased the content of a Sm alpha-actin protein. Maximal decrease of 70% was observed after 24 h of treatment. CTX also caused a 90% decrease of the actin mRNA level. CTX treatment completely abolished PDGF-BB stimulated DNA-synthesis although PDGF-Rbeta level and subcellular distribution and translocation was not altered. Furthermore CTX attenuated the PDGF-BB-induced tyrosine phosphorylation of the PDGF-Rbeta, PI 3'-K, PLC-gamma1 and ERK1/2 indicating an action of cyclic AMP on PDGF-beta receptor. We conclude that although cyclic AMP attenuates the PDGF-Rbeta mediated intracellular transduction pathway, an intact actin filament may be required for the PDGF-BB-induced DNA synthesis in VSMCs.

Actins↗
PubMed2000

Short-term stimulation of vascular smooth muscle cells with platelet-derived growth factor (PDGF)-BB and angiotensin II induces.

Growth factors such as the platelet-derived growth factor (PDGF)-BB and angiotensin II (Ang II) have been shown to induce vascular smooth muscle cell (VSMC) proliferation after long stimulation periods. Little is known though, about the effects of PDGF-BB and Ang II on VSMC proliferation after short stimulation periods. The purpose of our study was to examine whether a short term (3-60 min) stimulation of VSMC with PDGF-BB or Ang II is sufficient to induce cell proliferation. Incubation of VSMC with Ang II (100 nM) or PDGF-BB (50 ng/ml) caused a significant increase in [3H]thymidine incorporation starting after a 3-min stimulation, while the cell counts required 32 and 8 h of stimulation, respectively. Mitogen-activated protein kinase activation reached a maximum at 5-10 min of PDGF-BB or Ang II stimulation. This study demonstrates that the growth-promoting effects of PDGF-BB and Ang II are strongly dependent on the length of the stimulation period and that while prolonged stimulation periods (>8-32 h) result in VSMC proliferation, short ones (3-60 min) result only in [3H]thymidine incorporation without an increase in cell count, a fact of considerable pathophysiological significance, considering that the time kinetics of growth factors in the VSMC microenvironment have not as yet been clarified.

Angiotensin II↗
PubMed2000

High percentage of false-positive results of cytokeratin 19 RT-PCR in blood: a model for the analysis of illegitimate gene expression.

Cytokeratin 19 (CK19) RT-PCR is widely used in order to detect circulating tumor cells in peripheral blood and bone marrow. However, increasing amounts of information support the fact that it is also associated with a high percentage of false-positive results. In our study, we not only managed to demonstrate the significant limitations of this method, but were also able to clarify the reasons behind these limitations. We developed a completely novel RT-PCR for CK19 and sequenced an intron at nucleotide (nt) 980 of the CK19 mRNA to exclude DNA contamination. Tumor dilution experiments were performed in order to analyze the specificity and sensitivity of the method. Control experiments using the blood of healthy donors were performed. Tumor cell dilution experiments gave a detection limit of one tumor cell. If tumor cells were mixed with an equal volume of pure mononuclear cells, the detection limit was 1 tumor cell in 10(5) mononuclear cells. RT-PCR of mononuclear cells from healthy blood donors gave false-positive results in 29% of the cases. We conclude that a significant decrease in the sensitivity of CK19 RT-PCR occurs if it is performed in blood cells and that the illegitimate CK19 gene expression in normal cells can lead to false-positive results. These limitations have to be taken into account if RT-PCR is to be used for the detection of tumor cells either in blood or in bone marrow in clinical practice.

Blood Donors↗
PubMed2000

Metastatic tumors in the sellar and parasellar regions: clinical review of four cases.

Metastatic tumors in the sellar and parasellar regions are uncommon and rarely detected in clinical practice. We present four cases of sellar and parasellar metastatic tumors, which metastasized from distant organ in one case and extended directly from adjacent structures in three. Common presenting symptoms were cranial neuropathies, headache and facial pain. Invasion into the cavernous sinus was noted in all cases. We report rare cases of sellar and parasellar metastases. Also, we should consider the possibility of metastasis in these regions for patients who showed the above clinical presentations in systemic cancer patients. In extensive diseases, transient symptomatic relief could be obtained by direct surgical management, even in restricted degree.

Adenocarcinoma↗
PubMed2000

Tumour necrosis factor-alpha gene expression and production in human umbilical arterial endothelial cells.

Endothelial cells act as an interface between the blood and tissues, and are known to be involved in inflammatory processes. These cells are responsive to and produce different cytokines. Tumour necrosis factor-alpha (TNF-alpha) not only is one of the most important inflammatory peptides, but also can be induced by lipopolysaccharide (LPS). The focus of the present study was on TNF-alpha gene expression and production in human umbilical arterial endothelial cells (HUAEC), including the kinetics of this process. Interleukin-1alpha (IL-1alpha), LPS and TNF-alpha, which are all known to be elevated in septic shock, were used as stimulators at concentrations commonly found in patients with sepsis. Through the use of reverse transcriptase/PCR, immunohistochemical reactions and ELISA techniques, we showed that, in HUAEC, all three stimuli were able to induce gene expression and production of TNF-alpha. Furthermore, this induction by IL-1alpha, LPS and TNF-alpha occurred in a time- and concentration-dependent manner in these cells. TNF-alpha expression and production was induced by all three agents at concentrations commonly found in patients with sepsis. TNF-alpha mRNA was observed within 30 min regardless of the stimulus used, but the levels peaked at different times. Since it is well established that TNF-alpha is able to induce the synthesis of IL-1alpha in endothelial cells and, as shown in the present study, TNF-alpha and IL-1alpha are themselves able to induce the synthesis of TNF-alpha in endothelial cells, an autocrine potentiation of cytokine release in sepsis can be proposed. This situation could lead to a locally acting 'vicious cycle' which, when considered in addition to the known ability of TNF-alpha to induce apoptosis, could mean that various organs will be damaged, a condition associated with sepsis. Thus these results provide further evidence for the important role played by the endothelium in inflammation.

Blotting, Southern↗
PubMed2000

[Aortocaval fistula with acute right heart failure during surgery: case report].

A 71-year-old man was transferred to our institution with suspected of impending rupture of the abdominal aorta. The clinical manifestations included abdominal pain, pulsatile mass, and abdominal bruit. We made on early diagnosis of aortocaval fistula based on enhanced computed tomography and color Doppler flow imaging. Surgical repair was performed 24 hours after the onset of symptoms. At the introduction of anesthesia, cardiac arrest with high central venous pressure occurred. After resuscitation and rapid clamping of the proximal aorta, surgical closure of the fistula with graft replacement was performed successfully.

Aged↗
PubMed2000

[A surgical case of abdominal aortic aneurysm accompanied by hamartomatous changes in the vascular wall].

The current patient was a 22-year-old woman with dyspnea on exertion that had exacerbated over the past two to three years. Chest X-ray indicated pneumothorax in the right lung, and chest computed tomography showed diffuse microcysts in both lungs. The patient was diagnosed with lymphangiomyomatosis based on pleural biopsy by intrathoracic endoscopy. Systemic testing revealed complications of tuberous sclerosis and abdominal aortic aneyrysm, and a prosthetic graft replacement was perfomed following pneumothorax treatment. Aortic wall tissue images showed hamartomatous changes in smooth muscle tissue, similar to the pulmonary lesion, and this was thought to have caused vascular fragility and aneurysmal change.

Adult↗
PubMed1999

Cytokine-inducible growth factor gene expression in human umbilical endothelial cells.

Endothelial cells are known to be involved in different growth promoting processes like angioneogenesis, atherosclerosis or haematopoiesis. A great number of polypeptide growth factors crucial in this context have been isolated and they may be expressed in endothelial cells in either a constitutional or an inducible manner. The aim of the study was to examine the cytokine-inducibility of growth factor gene expression in endothelial cells. As uniform stimulators interleukin 1-alpha (IL-1alpha) and tumour necrosis factor (TNF)-alpha were chosen. Human umbilical arterial endothelial cells (HUAEC) were treated with either IL-1alpha or TNF-alpha and the gene expression of various growth factors was detected by reverse transcription-polymerase chain reaction (RT-PCR). We could demonstrate in HUAEC that stimulation with IL-1alpha- and TNF-alpha led to the mRNA expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) which are crucial in the process of angioneogenesis and atherosclerosis as well as of the granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF) and stem cell factor (SCF) which are main growth factors in haematopoiesis. The demonstration of the inducibility of a wide range of various growth factor genes in endothelial cells is of major interest regarding the growth regulatory role of the endothelium.

Cells, Cultured↗
PubMed1999

Real-time PCR-analysis of the cytochrome P450 1B1 codon 432-polymorphism.

The aim of the present study was to develop and validate a rapid assay for genotyping of CYP1B1 codon 432-polymorphism. The described method is a single tube assay and combines both rapid-cycle polymerase chain reaction (PCR) with real-time monitoring by amplification and generation of the melting profiles of an allele-specific fluorescent probe. With this method 300 samples were analysed from healthy, unrelated Germans. Genotype frequency determined for the mutated allele CYP1B1*2 was 0.40. The results show that genotyping of CYP1B1 codon 432-polymorphism with a real-time fluorescence PCR method is a rapid and reliable assay for the analysis of large numbers of samples.

Alleles↗
PubMed1999

Lysophosphatidic acid stimulates protein kinase C isoforms alpha, beta, epsilon, and zeta in a pertussis toxin sensitive pathway in vascular smooth muscle cells.

The natural phospholipid lysophosphatidic acid (LPA) has been characterized as an important vascular smooth muscle cell (VSMC) mitogen whose effects are mainly mediated by pertussis toxin (PTX)-sensitive guanosine triphosphate (GTP)-binding protein (Gi-protein). Protein kinase C (PKC) isoforms play an important role in intracellular signaling cascades and in growth of VSMC. In the present study we investigated the effect of LPA on activation of PKC isoforms alpha, beta, epsilon, and zeta in VSMC by Western blot of cytosolic and membrane fractions. Furthermore, we examined the role of PKC activation on LPA-induced growth of VSMC using PKC inhibitor 19-27. Stimulation of VSMC by 5 microg/mL LPA for 10 min increased the amount of PKC alpha, beta, epsilon, and zeta in the particulate fraction by 689%, 285%, 424%, and 510%, respectively, and returned to control level after 30 min. Correspondingly, the amount of PKC alpha, beta, epsilon, and zeta in the cytosolic fraction decreased by 32%, 94%, 44%, and 95%, respectively, compared to control. Furthermore, we could show that LPA-induced activation of PKC alpha, beta, epsilon, and zeta isoforms was PTX sensitive. Incubation of VSMC with nonspecific PKC inhibitor 19-27 (10 micromol/L) for 24 h resulted in a 30% inhibition of LPA-induced DNA synthesis as measured by [3H]thymidine incorporation. In conclusion, in VSMC LPA stimulated translocation of PKC isoforms alpha, beta, epsilon, and zeta in a PTX-sensitive manner. Furthermore stimulation of PKC might be critically involved in LPA-induced mitogenesis in VSMC.

Animals↗
PubMed1999

Early intracellular signalling pathway of ethanol in vascular smooth muscle cells.

1. ERKs belong to MAP kinase family and are activated by several growth and stress factors. Although ethanol has been shown to modulate ERK1 and ERK2 (p44(mapk) and p42(mapk)) activity, it can also act as an antiproliferative agent in various mammalian cells. Since the nature of the antiproliferative effect of ethanol in VSMCs has not been defined, we examined its effects on growth and on early intracellular events normally induced by growth factors in VSMCs. 2. Measurement of cytosolic Ca(2+) and pH in cell monolayers was performed using fura-2/AM and BCECF/AM, respectively. The effect of ethanol on VSMCs growth was assessed by [(3)H]-thymidine incorporation, by cell counting and by determination of the caspase 3 activity. Stimulation of ERK1 and ERK2 was examined by the chemiluminescence Western blotting method. The expression of c-fos was quantitated by Northern blotting. Determination of inositolphosphates was performed after labelling of VSMCs with myo-[2-(3)H]-inositol and separation of inositolphosphates by HPLC. 3. Ethanol (0.3 - 1.0% v v(-1), 17 - 170 mM) induced a dose-dependent maximal stimulation of p44(mapk)/p42(mapk) at 30 min and expression of c-fos mRNA with a maximum at 120 min. Intracellular events upstream to MAP kinase, like an increase in [Ca(2+)](i), activation of the Na(+)/H(+) exchanger and formation of phosphoinositol metabolites were also markedly activated by ethanol. Treatment of VSMCs with ethanol for 3 - 5 min induced an increase in DNA synthesis whereas treatment of the cells for more than 30 min was toxic. Caspase 3 activity was not modulated by ethanol treatment of VSMCs. 4. We may postulate that the activation of these mitogenic signals including the elevation of DNA synthesis reflects a cell effort to protect itself against the toxic effects of ethanol.

Animals↗
PubMed1999

Occurrence of urinary tract tumors in miners highly exposed to dinitrotoluene.

Between 1984 and 1997, six cases of urothelial cancer and 14 cases of renal cell cancer occurred in a group of 500 underground mining workers in the copper-mining industry of the former German Democratic Republic, with high exposures to explosives containing technical dinitrotoluene. Exposure durations ranged from 7 to 37 years, and latency periods ranged from 21 to 46 years. The incidences of both urothelial and renal cell tumors in this group were much higher than anticipated on the basis of the cancer registers of the German Democratic Republic by factors of 4.5 and 14.3, respectively. The cancer cases and a representative group of 183 formerly dinitrotoluene-exposed miners of this local industry were interviewed for their working history and grouped into four exposure categories. This categorization of the 14 renal cell tumor cases revealed no dose-dependency concerning explosives in any of the four exposure categories and was similar to that of the representative group of employees, whereas the urothelial tumor cases were predominantly confined to the high-exposure categories. Furthermore, all identified tumor patients were genotyped by polymerase chain reaction, using lymphocyte DNA, regarding their genetic status of the polymorphic xenobiotic metabolizing enzymes, including the N-acetyltransferase 2 and the glutathione-S-transferases M1 and T1. This genotyping revealed remarkable distributions only for the urothelial tumor cases, who were exclusively identified as "slow acetylators." This points to the possibility of human carcinogenicity of dinitrotoluene, with regard to the urothelium as the target tissue.

Aged↗