Biomedical subjects

K Hibi

Publications and source records attributed to K Hibi.

At least 37 records · Page 2Linked to original sources

PubMed2000

Automated contour detection for high-frequency intravascular ultrasound imaging: a technique with blood noise reduction for edge enhancement.

Automated edge detection may standardize measurements among observers, providing for rapid assessment of intravascular ultrasound (IVUS) images. However, with high frequency images, enhanced blood signals make it difficult to define and trace the lumen borders. Accordingly, we evaluated a fully automated contour analysis facilitated with a blood noise reduction algorithm (BNR) for 40-MHz IVUS images in human coronary arteries of 27 patients. This algorithm is based on the principle that blood echo speckles have higher temporal and spatial variations than the arterial wall. A total of 193 paired lumen areas and 78 external elastic membrane (EEM) areas were measured and compared. Automated measurements showed good agreement with manual tracings for lumen and EEM area, with high correlation coefficients (0.945 and 0.950, respectively) and small variability (0.4 +/- 14.4% and 0.6 +/- 9.7%, respectively). This preliminary finding suggests that automated contour detection facilitated with BNR appeared to be a feasible and reliable technique for area measurements in 40-MHz IVUS imaging.

Blood↗

PubMed2000

The ratio of splicing variants of MGC-24/CD164, a sialomucin, correlates with the metastatic potential of colorectal carcinomas.

MGC-24/CD164 is a sialomucin expressed in many normal and cancerous tissues. In humans, soluble and transmembrane forms of MGC-24 are produced by alternative splicing. The total MGC-24 RNA level was found to be lower in human colorectal carcinomas as compared with the adjacent normal mucosal tissues. Lower MGC-24 mRNA levels in colon carcinomas and in the adjacent normal mucosa epithelium correlate with lymphatic vessel invasion by the carcinoma. The ratio of the soluble form to the transmembrane form of the mRNA in colorectal carcinomas was determined by ribonuclease protection assay. Higher ratios were correlated with less venous invasion and less remote metastasis, which became evident during postoperative observation.

Alternative Splicing↗

PubMed2000

PGP9.5 as a prognostic factor in pancreatic cancer.

The expression of PGP9.5 was evaluated using immunohistochemistry in 69 resected ductal carcinomas of the pancreas and in normal pancreatic tissue. Overexpression did not seem to differ with histological type or pathological stage. A significant negative correlation was found between overexpression of PGP9.5 and postoperative survival. Multivariate analysis also suggested PGP9.5 along with tumor stage and extrapancreatic plexus invasion as strong predictors of the outcome. This study suggests that PGP9.5 expression may be used as a marker for predicting the outcome of resection-treated pancreatic cancer patients.

Adenocarcinoma↗

PubMed1999

Mutation analysis of hBUB1 in aneuploid HNSCC and lung cancer cell lines.

Aneuploidy is frequently observed in many types of human cancer cells, suggesting that mutations of genes required for chromosomal stability may occur in human tumors. The BUB gene is a component of the mitotic checkpoint in budding yeast that delays anaphase in the presence of spindle damage thus increasing the probability of successful delivery of a euploid genome to each daughter cell. Recently, human homologues of the BUB gene were identified and mutant alleles of hBUB1 were detected in two colorectal tumor cell lines. Transfection of one mutant allele led to dominant disruption of the mitotic checkpoint control in a euploid cell, suggesting that aneuploidy in some tumors could be due to defects in the mitotic checkpoint. We analyzed the entire coding sequence of hBUB1 for mutation in 31 head and neck squamous cell carcinoma (HNSCC) and lung cancer cell lines, most with severe aneuploidy. We found expression of the hBUB1 gene in all cell lines and only a single nucleotide substitution in one cell line without a resultant change in amino acid sequence. Our study demonstrates that hBUB1 is rarely a target for genetic alterations in tumors of the respiratory tract.

Aneuploidy↗

PubMed1999

PGP9.5 as a candidate tumor marker for non-small-cell lung cancer.

PGP9.5 is a neurospecific peptide that functions to remove ubiquitin from ubiquitinated proteins and prevents them from targeted degradation by proteasomes. Using the serial analysis of gene expression method (SAGE), we observed that the PGP9.5 transcript was highly expressed in primary lung cancers and lung cancer cell lines but was not detectable in the normal lung. Here we examined the expression of PGP9.5 protein in normal lung epithelium, lung tumor cell lines, and 98 resected primary non-small-cell lung carcinomas (NSCLCs). We found PGP9.5 reactivity in normal lung in a pattern compatible with K-cells of the diffuse neuroendocrine system. However, the PGP9.5 was present in both small-cell lung cancer (SCLC) and NSCLC cell lines (22/24) independent of neuronal differentiation. In primary NSCLCs, 54% (53/98) of the cases had positive PGP9.5 staining, and the expression of protein was strongly associated with pathological stage of the cancer. It was present in 44% (29/66) of stage I NSCLCs and in 75% (24/32) of stage II and IIIA NSCLCs (p = 0.0032). These results suggest that the increased expression of PGP9.5 is specifically associated with lung cancer development and may serve as a potential marker for the detection of lung cancer.

Basic Helix-Loop-Helix Proteins↗

PubMed1999

Angiotensinogen gene polymorphism near transcription start site and blood pressure: role of a T-to-C transition at intron I.

Molecular variants of the angiotensinogen gene, a key component of the renin-angiotensin system, are considered genetic risk factors for primary hypertension. A relation between the angiotensinogen gene locus and hypertension has been found in whites, Japanese, and African Caribbeans but not in Chinese. The lack of a consistent association between M235T polymorphism at exon 2 and hypertension has suggested that another site in linkage disequilibrium with M235T is the causal mutation. We studied the relations among plasma angiotensinogen concentrations, blood pressure, related clinical variables, and mutations of the 5' upstream core promoter region of the human angiotensinogen gene in 274 subjects recruited from our outpatient clinic. We confirmed that plasma angiotensinogen concentration was significantly correlated with A-20C mutation and percent body fat and found that systolic and diastolic blood pressures were significantly correlated with G-6A and T+68C mutations. These results suggest that mutations near the transcription start site may be associated with increased blood pressure.

Angiotensinogen↗

PubMed1999

Molecular detection of neoplastic cells in lymph nodes of metastatic colorectal cancer patients predicts recurrence.

Disseminated disease, especially to the liver, constitutes the major risk of recurrence for colorectal cancer patients. However, successful resection can still be achieved in 25-35% of colorectal cancer patients with isolated metastases. To evaluate the clinical value of occult micrometastatic disease detection in lymph nodes, we tested genetic (K-ras and p53 gene mutations) and epigenetic (p16 promoter hypermethylation) molecular markers in the perihepatic lymph nodes from colorectal cancer patients with isolated liver metastases. DNA was extracted from 21 paraffin-embedded liver metastases and 80 lymph nodes from 21 colorectal cancer patients. K-ras and p53 gene mutations were identified in DNA from liver metastases by PCR amplification followed by cycle sequencing. A sensitive oligonucleotide-mediated mismatch ligation assay was used to search for the presence of K-ras and p53 mutations to detect occult disease in 68 lymph nodes from tumors positive for these gene mutations. Promoter hypermethylation at the p16 tumor suppressor gene was examined in both liver lesions and lymph nodes by methylation-specific PCR. Sixteen of the 21 (76%) liver metastases harbored either gene point mutations or p16 promoter hypermethylation. Twelve of the 68 lymph nodes were positive for tumor cells by molecular evaluation and negative for tumor cells by histopathology and cytokeratin immunohistochemistry, whereas none were positive for tumor cells by histopathology or negative for tumor cells by molecular analysis (P = 0.0005, McNemar's test). Moreover, in three patients with lymph nodes that were histologically negative at all sites, molecular screening detected tumor DNA at one or more lymph nodes. Survival analysis showed a median survival of 1056 days for patients without evidence of lymph node involvement by molecular analysis and 165 days for patients with positive lymph nodes by this approach (P = 0.0005). These results indicate that lymph node metastasis screening in colorectal cancer patients by molecular-based techniques increases the sensitivity of tumor cell detection and can be a good predictor of recurrence in colorectal cancer patients with resectable liver metastases.

Colorectal Neoplasms↗

PubMed1998

Serial analysis of gene expression in non-small cell lung cancer.

We used the serial analysis of gene expression (SAGE) method to systematically analyze transcripts present in non-small cell lung cancer. Over 226,000 SAGE tags were sequence analyzed from two independent primary lung cancers and two normal human bronchial/tracheal epithelial cell cultures. A total of 226,000 SAGE tags were sequence identified, representing 43,254 unique transcripts. Comparison of the tags present in the tumor with those identified in the normal tissue revealed 175 transcript tags that were overrepresented in the normal tissue and 142 tags that were overexpressed in the tumor by 10-fold or more. Northern hybridization was performed on 15 of the most abundantly expressed tags identified in the tumors. These tags were derived from either a known gene or a matched expressed sequence tag clone. The transcripts for 3 of the 15 genes, PGP 9.5, B-myb, and human mutT, were abundantly expressed in primary lung cancers (10 of 18, 15 of 18, and 6 of 12 tumors, respectively). In contrast, the presence of PGP9.5 and B-myb was much less frequent in primary tumors derived from other tissue origins. These results suggest that at least a portion of the transcripts identified by SAGE are frequently associated with lung cancer, and that their overexpression may contribute to lung tumorigenesis. The identification and further characterization of genes generated by SAGE should provide potential new targets for the diagnosis, prognosis, and therapy of lung cancer.

Bronchi↗

PubMed1998

Molecular detection of genetic alterations in the serum of colorectal cancer patients.

We have searched for the presence of genetic alterations in serum DNA obtained from 44 colorectal cancer patients. Microsatellite analysis using highly polymorphic markers revealed loss of heterozygosity and/or microsatellite instability in 35 of 44 (80%) primary tumors. No alterations were detected in the paired serum DNA. We next used an oligonucleotide-mediated mismatch ligation assay to detect tumor specific gene mutations in the serum. Among the 16 cases with a K-ras gene mutation in the tumor, the same mutation was detected in three paired serum samples. In the 10 cases with a p53 mutation in the tumor, the identical mutation was detected in seven corresponding serum samples. Comparison of the molecular analysis with clinical diagnosis of these patients revealed that none of the seven Dukes' stage B patients with a K-ras mutation in their tumors demonstrated a mutation in the serum. In contrast, five of seven stage B patients with a p53 mutation in the tumor demonstrated a mutation in the paired serum (P = 0.01, Fisher's exact test). Taken together, either a K-ras or p53 mutation was detected in the serum in 40% of the 25 patients (95% confidence interval, 21-61%), whose primary tumors contained a mutation and in 23% of the 44 patients (95% confidence interval, 12-38%) with colorectal cancer. The frequent detection of p53 mutation in the serum of patients with early stage tumors suggests a possible use of this approach for clinical prognosis and cancer monitoring of colorectal cancer patients.

Alleles↗

PubMed1998

Angiotensin-converting enzyme gene polymorphism in Nepal.

It has recently been found that there were very few hypertensives in the inhabitants of one Nepalese village, even though their salt consumption, per capita, was as high as citizens in many western countries. To evaluate the genetic factors involved in this phenomenon, we studied whether they had a special genotype distribution of angiotensin-converting enzyme (ACE) gene I/D polymorphism, which was recently reported to be involved in salt sensitivity. One hundred and thirty-eight subjects were evaluated in Nepal. Only nine subjects (6.5%) in this population were hypertensives (over 140/90 mm Hg) while consuming 11 g salt/day, which confirmed the previous results. The distribution of genotypes and alleles of ACE gene I/D polymorphism was similar to that in the Japanese and Chinese, who had five-times more hypertensives while consuming almost as much salt as Nepalese, but significantly different from those in Caucasians. The present study reports, for the first time, the genotype distribution of ACE gene I/D polymorphism in Nepalese subjects. Furthermore, the results suggest ACE gene polymorphism may not be involved in the 'salt-resistance' in this population.

Aged↗

PubMed1998

Endocrinological abnormalities in angiotensinogen-gene knockout mice: studies of hormonal responses to dietary salt loading.

OBJECTIVE: Physiological roles of the renin-angiotensin system in maintaining blood pressure and sodium-water balance in angiotensinogen gene-knockout mice were evaluated with special reference to endogenous pressor substances. METHODS: Angiotensinogen-gene knockout mice and control mice were fed a 0.3 or 4% NaCl diet for 2 weeks. Systolic blood pressure and urinary excretions of electrolytes, creatinine, aldosterone, adrenaline, noradrenaline, dopamine and vasopressin were measured. RESULTS: About 60% of our angiotensinogen-gene knockout mice did not survive until weaning. These mice presented with hypotension and polyuria. Urinary excretion of aldosterone from such mice was significantly lower (not detected) than that from control mice (2.0+/-0.3 pg/mg creatinine). In contrast, urinary excretion of vasopressin from angiotensinogen-gene knockout mice (0.7+/-0.1 ng/mg creatinine) was greater than that from control mice (0.3+/-0.1 ng/mg creatinine), and those of adrenaline and of noradrenaline were similar for knockout and control mice. After salt loading (a 4% NaCl diet), angiotensinogen-gene knockout mice exhibited a significant increase in systolic blood pressure (from 68.3+/-2.9 to 95.9+/-5.9 mmHg), significant decreases in urinary excretions of adrenaline (from 65+/-8 to 40+/-7 pg/mg creatinine) and noradrenaline (from 467+/-48 to 281+/-41 pg/mg creatinine) and no change in excretion of vasopressin compared with such mice fed a 0.3% NaCl diet CONCLUSION: The present results with angiotensinogen-gene knockout mice confirm that the renin-angiotensin system plays fundamental roles in maintaining the blood pressure and sodium-water balance. Because the vasopressin and catecholaminergic systems may be altered by lack of angiotensin in angiotensinogen-gene knockout mice, these systems perhaps are not able to restore blood pressure and sodium-water depletion to normal levels in these mice.

Aldosterone↗

PubMed1998

A prospective randomized study of amoxycillin and omeprazole with and without metronidazole in the eradication treatment of Helicobacter pylori.

A combination of amoxycillin and omeprazole is often used to treat Helicobacter pylori infection. A three-drug regimen comprising metronidazole, amoxycillin and omeprazole has been proposed as an alternative therapy. In a prospective, randomized, comparative study, we evaluated these two regimens with respect to safety and efficacy in patients with H. pylori infection. Sixty patients with peptic ulcer (gastric, 32 patients; duodenal, 28 patients) who had a history of ulcer recurrence were randomly assigned to dual therapy with amoxycillin (500 mg three times daily for 2 weeks) and omeprazole (20 mg once daily for 8 weeks) or to triple therapy with metronidazole (500 mg twice daily for 2 weeks) plus amoxycillin and omeprazole, given in the same dosages as dual therapy. Forty-eight patients completed the protocol; treatment was discontinued because of side effects in nine patients, and three patients dropped out of the study. On the basis of all patients treated, the rate of H. pylori eradication was significantly higher for triple therapy 20/23 cases, 87.0%; 95% confidence interval (CI), 0.664-0.972) than for dual therapy 13/25, 52.0%; 0.313-0.722; P < 0.05). On an intention-to-treat basis, the difference between the groups in the rate of H. pylori eradication was marginally significant (P = 0.06 [0.028-0.512]). Side effects were reported by five patients receiving triple therapy (skin rash, one; nausea, two; headache, one; abdominal pain, one), and four patients receiving dual therapy (skin rash, two; abdominal pain, one; diarrhoea, one). All side effects resolved spontaneously after termination of treatment. There was no significant difference in safety between the two regimens. Triple therapy with metronidazole, amoxycillin, and omeprazole was significantly more effective for the eradication of H. pylori than dual therapy with amoxycillin and omeprazole alone. The safety of these regimens was similar, and triple therapy was found to be clinically acceptable.

Adult↗

PubMed1998

Activation of angiotensinogen gene in cardiac myocytes by angiotensin II and mechanical stretch.

Circulating and cardiac renin-angiotensin systems (RAS) play important roles in the development of cardiac hypertrophy. Mechanical stretch of cardiac myocytes induces secretion of ANG II and evokes hypertrophic responses. Angiotensinogen is a unique substrate of the RAS. This study was performed to examine the regulation of the angiotensinogen gene in cardiac myocytes in response to ANG II and stretch. ANG II and stretch significantly increased the levels of angiotensinogen mRNA in cardiac myocytes. Actinomycin D completely inhibited ANG II- and stretch-mediated increases in angiotensinogen mRNA. Although CV-11974 abolished ANG II-mediated increases in mRNA level and promoter activity of the angiotensinogen gene, the inhibition of stretch-mediated activation by CV-11974 was significant but not complete. These results indicate that ANG II activates transcription of the angiotensinogen gene exclusively via ANG II type 1-receptor pathway and that stretch activates such transcription mainly via the same pathway in cardiac myocytes. Furthermore, factors other than ANG II may also be involved in stretch-mediated activation of the angiotensinogen gene in cardiac myocytes.

Angiotensin II↗

PubMed1998

Endothelial nitric oxide synthase gene polymorphism and acute myocardial infarction.

Recently a point mutation of guanine to thymine at nucleotide position 1917 in the endothelial nitric oxide synthase (eNOS) gene has been reported to be associated with coronary artery spasm. In addition, a significant association of the 4a/b polymorphism in intron 4 of the eNOS gene with coronary artery disease has been reported. However, the implications of these polymorphisms with respect to acute myocardial infarction (AMI) remain to be established. We conducted a case-control study of 226 patients with AMI and 357 healthy gender- and age-matched control subjects. In the former group, coronary angiograms were evaluated according to angiographic criteria based on the number of diseased vessels (>/=75%) and the number of stenotic lesions (>/=50%). Homozygosity for the Glu-Asp298 polymorphism existed in 5 of 226 patients with AMI (2.2%) but not in any of the 357 control subjects (P=.0085). However, when we evaluated the coronary angiograms of 226 case patients, there was no difference in the number of diseased vessels or the number of stenotic lesions between the patients with this homozygote and those without it. By contrast, there was no evidence of a significant increase in the risk of AMI or the severity of coronary atherosclerosis among individuals with the a/a genotype of the eNOS4a/b polymorphism. Our results imply that patients who are homozygous for the Glu-Asp298 polymorphism may be genetically predisposed to AMI; however, this mutation apparently is not related to the severity of coronary atherosclerosis. Further studies are needed to confirm our results and characterize the molecular mechanisms by which eNOS is involved in susceptibility to AMI.

Case-Control Studies↗

PubMed1998

Developmental changes in expression of angiotensinogen mRNA in rat nephron segments.

We studied the localization of angiotensinogen mRNA in rat nephron segments and the differences in angiotensinogen mRNA levels between male Sprague-Dawley rats at 6 and 12 wk of age using reverse transcription and polymerase chain reaction (RT-PCR). Each nephron segment of the rat kidney was microdissected. Total RNA was prepared and used in the following RT-PCR assay. The PCR products were size-fractionated by agarose gel electrophoresis, visualized with ethidium bromide staining, and identified by Southern blot analysis. The relative amounts of products were determined by densitometry. Strong bands corresponding to angiotensinogen mRNA were detected from proximal convoluted and straight tubules, and weaker bands were found in glomeruli. The signals in all tissues in 12-wk-old rats were weaker than those in 6-wk-old rats. Since local angiotensinogen is the unique substrate of the tissue renin-angiotensin system and exerts an autocrine-paracrine influence on renal function, the changes in tubular angiotensinogen may be related to physiological and morphological changes in the rat kidney during development.

Angiotensinogen↗

PubMed1998

[A patient with disopyramide intoxication rescued by percutaneous cardiopulmonary support].

A 28-year-old man was admitted to our hospital in a hypotensive state 2 hours after taking 8,400 mg disopyramide. Infusion of catecholamine and gastric lavage restored normal blood pressure. However, 8 hours after taking the disopyramide he became hypotensive again and electrocardiographic findings revealed bizarre ventricular complexes resulting in ventricular flutter. Although standard cardiopulmonary resuscitation was not effective, his circulatory status was maintained by percutaneous cardiopulmonary support (PCPS). After 36 hours electrocardiography showed sinus rhythm, and his cardiac function became normal. Patients with severe cardiac dysfunction or cardiac arrest caused by disopyramide intoxication can be supported by PCPS until cardiac function is restored.

Adult↗

PubMed1997

A novel proximal element mediates the regulation of mouse Ren-1C promoter by retinoblastoma protein in cultured cells.

The protein product of the retinoblastoma susceptibility gene, RB, is a nuclear phosphoprotein that modulates transcription of genes involved in growth control via interactions with transcription factors. Renin is a rate-limiting enzyme of the renin-angiotensin system that regulates blood pressure and water-electrolyte balance. Renin gene expression is regulated in a tissue-specific and developmentally linked manner. Similarly, the expression of RB is controlled in a differentiation-linked manner. Thus, to investigate whether RB is involved in the regulation of renin gene expression, we examined the effects of RB on transcriptional activity of the mouse renin (Ren-1C) promoter. The Ren-1C promoter contains two transcriptionally important elements; the RU-1 (-224 to -138) and RP-2 (-75 to -47) elements. RB activated the Ren-1C promoter in human embryonic kidney cells. The promoter element responsible for RB-mediated transcriptional regulation was the RP-2 element. The results of DNA-protein binding experiments showed that RB increased nuclear binding activity to the RP-2 element, and site-directed mutation which disrupted binding of nuclear factors to the RP-2 element markedly reduced RB-mediated activation of Ren-1C promoter in human embryonic kidney cells. These results indicate that the RP-2 element plays an important role in RB-mediated transcriptional regulation of Ren-1C promoter activity in human embryonic kidney cells, thereby suggesting an interesting mechanism by which RB may modulate the renin-angiotensin system.

Activating Transcription Factors↗

PubMed1997

Stretch-induced MAP kinase activation in cardiomyocytes of angiotensinogen-deficient mice.

The renin-angiotensin system plays an important role in the hypertrophic responses in cardiac myocytes through the activation of signal transduction pathways and expression of oncogenes. In the present study, we examined mechanical stretch-induced activation of mitogen-activated protein kinases (MAP kinases) using cultured cardiac myocytes derived from neonatal angiotensinogen gene deficient mice (Agt-/-) and neonatal wild type mice (Agt+/+). Within 2 minutes of being added to cardiac myocytes, angiotensin II activated MAP kinases and the response was completely blocked by pretreatment of the cardiac myocytes with CV-11974, a selective antagonist of angiotensin II type 1 receptors. Interestingly, mechanical stretch resulted in significantly greater activation of MAP kinases in Agt-/- cardiac myocytes than in Agt+/+ cardiac myocytes. CV-11974 failed to suppress the stretch-induced activation of MAP kinases in Agt-/- cardiac myocytes while it inhibited the activation in Agt+/+ cardiac myocytes. BQ123, an endothelin type A receptor antagonist, had no effect on stretch-induced activation of MAP kinases in cardiac myocytes from either mouse strain. These results suggest that cardiac RAS is important for stretch-induced MAP kinase activation in Agt+/+ cardiac myocytes; however, angiotensin II is not indispensable for mechanical stretch-induced activation of MAP kinases in Agt-/- cardiac myocytes.

Angiotensin II↗