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Biomedical subjects

Y Yamaguchi

Publications and source records attributed to Y Yamaguchi.

At least 541 records · Page 30Linked to original sources
PubMed1996

Detection of K-ras point mutations at codon 12 in pancreatic juice for the diagnosis of pancreatic cancer by hybridization protection assay: a simple method for the determination of the types of point mutation.

The present study was undertaken to detect K-ras oncogene point mutations at codon 12 in pure pancreatic juice (PPJ) by the hybridization protection assay (HPA) method for the diagnosis of pancreatic cancer (PC). This assay can be carried out within 30 min and can determine not only the presence of a mutation, but also the mutational type of K-ras at codon 12. The minimal ratio of mutant DNA detectable by the HPA was 5-10% of the total DNA. PPJ was collected through a cannula under duodenal fiberscope control from 20 patients with PC and 20 patients with chronic pancreatitis (CP). Analysis of PPJ by the HPA revealed that the incidence of K-ras point mutations at codon 12 was 55% (11/20) in patients with PC and 0% (0/20) in those with CP. Mutational types of K-ras at codon 12 in PC were aspartic acid (Asp) in nine cases, both Asp and cysteine in one case, and arginine in one case. Analysis of K-ras point mutations at codon 12 in PPJ using the HPA method seems promising as a new genetic test for the diagnosis of PC, because the HPA method is simple, and can easily determine the mutational type.

Base Sequence↗
PubMed1996

Immunogenicity of peptides coupled with multiple T-cell epitopes of a surface protein antigen of Streptococcus mutans.

A surface protein antigen (PAc) of Streptococcus mutans, in particular the A-region of the molecule, has been noted as a possible target of effective dental caries vaccine. We have previously shown that two peptides of 19 amino acids (residues 361-379, NAKATYEAALKQYEADLAA, and residues 301-319, ANAANEADYQAKLTAYQTE), which correspond to parts of the A-region, contain both T- and B-cell epitopes for the induction of cross-reacting antibodies to the PAc. In this study, for development of an appropriate antigen as a peptide vaccine for use in prophylactic dentistry, we analysed in detail the localization of the T- and B-cell epitopes of PAc(361-379) peptide and the T-cell epitope of PAc(301-319) peptide in B10 congenic mice. In four murine major histocompatibility complex (MHC) haplotypes (H-2f,d,a and k), PAc(361-377) peptide showed T- and B-cell epitopes forming a cluster. It was found that the antibody which was induced by the immunization with the peptide was strongly cross-reactive with recombinant (r)PAc. Meanwhile, PAc(305-318) peptide, recognised by five strains of mice of different MHC haplotypes (H-2f,d,a,k and s), also bore multiple T-cell epitopes. PAc(361-377) peptide coupled to PAc(305-318) significantly elevated cross-reacting antibody levels compared to immunization with PAc(361-377) only in four H-2 haplotypes. Moreover, a peptide with PAc(305-318) coupled to the N-terminal region of PAc(361-377) produced significant cross-reacting antibody against rPAc, even in B10.S mice which had not responded to immunization with PAc(361-379) peptide. Therefore, it was suggested that coupling among the peptides forming a cluster might be effective in increasing immunogenicity. These results may provide us with a useful strategy for the design of peptide-based vaccines for S. mutans in the future.

Amino Acid Sequence↗
PubMed1996

Nodular pulmonary amyloidosis associated with asbestos exposure.

A 71 year old man was admitted for the purpose of diagnosis of a right solitary pulmonary nodule. The size of the nodule was 18 x 18 mm in diameter 2 years ago, but it has become large, 25 x 25 mm in diameter. The nodule was resected by thoracotomy. Microscopically, eosinophilic amorphous, acellular substances were surrounded by inflammatory infiltrates. It stained with Congo red stain and showed green birefringence with polarizing microscopy. Amyloid fibrils were observed electron microscopically. Asbestos bodies were observed in the lung parenchyma around the nodule. This case shows that a nodule in nodular pulmonary amyloidosis can grow gradually and suggests the possibility of asbestos fibers as one of the etiologic factors in nodular pulmonary amyloidosis.

Aged↗
PubMed1996

Structural and functional features of bile canaliculi in adult rat hepatocyte spheroids.

Spheroids of adult rat hepatocytes are spherical cell aggregates which retain three-dimensional architecture and hepatocyte specific functions. In this study, we investigated the detailed structure and function of bile canaliculi in spheroids. Hepatocytes were prepared from adult rat liver and cultured with epidermal growth factor (50 ng/ml). Hepatocytes formed floating spheroids 4 days after inoculation. The morphology of hepatocyte spheroids was investigated after fluorescent staining for actin using confocal laser scanning microscopy and electron microscopy. To study the function of bile canaliculi, the transcellular transport of fluorescein diacetate was observed. These experiments were performed in a control group and in a group treated with the actin inhibitor cytochalasin B. In a control group, spheroids contained bile canalicular structures which were surrounded by actin filaments. Added fluorescent dye was secreted and pooled in bile canaliculi. Cytochalasin B caused marked distention of bile canaliculi and prominent accumulation of secreted fluorescent dye in dilated bile canaliculi. This phenomenon was based on the impairment of contractile movement of bile canaliculi. These results demonstrate that hepatocyte spheroids maintain functional and morphological peculiarity, and therefore this model may be useful in investigation of the mechanism of bile formation and intrahepatic cholestasis.

Actins↗
PubMed1996

Effects of cycloheximide on pancreatic endonuclease activity, apoptosis, and severity of acute pancreatitis.

The factors that determine the severity of acute pancreatitis are unknown, but a close inverse correlation between that severity and the extent of acinar cell apoptosis that follows the triggering signal has been previously noted [A. M. Kaiser, A. K. Saluja, A. Sengupta, M. Saluja, and M. L. Steer. Am. J. Physiol. 269 (Cell Physiol. 38): C1295-C1304, 1995]. In the present studies, we have evaluated internucleosomal DNA fragmentation and apoptosis within the pancreas and the effects of inhibiting protein synthesis by cycloheximide (CHX) on these phenomena as well as on the severity of pancreatitis. We report the constitutive presence of a Ca(2+)- and Mg(2+)-dependent endonuclease activity within pancreatic nuclei that is dependent on continued protein synthesis. Furthermore, we have found that CHX administration reduces the extent of apoptosis but significantly worsens the severity of pancreatitis that follows ligation of the rat common bile-pancreatic duct. These observations are consistent with the hypothesis that apoptosis is a teleologically beneficial response to acinar cell injury during acute pancreatitis.

Animals↗
PubMed1996

High-dose but not low-dose dexamethasone impairs glucose tolerance by inducing compensatory failure of pancreatic beta-cells in normal men.

The diabetogenic effects of glucocorticoids appear to be dose dependent. To determine the effects of different doses of dexamethasone on glucose metabolism, we performed frequently sampled intravenous glucose tolerance tests in 20 healthy young men. Glucose kinetics were analysed by the minimal model. Ten subjects received low-dose dexamethasone (2 mg/day) for 3 days, and the other 10 received high-dose dexamethasone (6 mg/day) for 3 days. The rate of glucose disappearance (KG) did not decrease in the low-dose group (2.46 +/- 0.20 to 2.19 +/- 0.11% min-1, P = 0.35). In contrast, KG in the high-dose group did decrease significantly (2.43 +/- 0.29 to 1.81 +/- 0.11% min-1, P < 0.05). The factor responsible for the decline in KG in the high-dose group was not glucose effectiveness because these values did not change in either group. The insulin sensitivity decreased significantly, by 46% in the low-dose group and 69% in the high-dose group [17.1 +/- 2.7 to 9.2 +/- 1.5 and 18.5 +/- 3.7 to 5.8 +/- 0.9 x 10(-5) min-1 (pmol/L)-1, P < 0.001 and P < 0.01, respectively]. The insulin area (0-20 min) increased significantly, by 104% in the low-dose group and 114% in the high-dose group [3412.6 +/- 609.7 to 6972.7 +/- 1450.1 and 4086.7 +/- 864.5 to 8750.0 +/- 1451.6 (pmol/L) min, P < 0.01 and P < 0.01, respectively]. Insulin sensitivity x insulin area as an estimate of insulin-dependent glucose uptake and insulin's action to suppress hepatic glucose production decreased significantly in the high-dose group (0.588 +/- 0.112 to 0.441 +/- 0.073, P < 0.05), but did not change in the low-dose group (0.436 +/- 0.050 to 0.484 +/- 0.032, P = 0.77). Therefore, the decline in KG in the high-dose group may be associated with the compensatory failure of pancreatic beta-cells against for the insulin resistance.

Adult↗
PubMed1996

Three extracellular chitinases in suspension-cultured rice cells elicited by N-acetylchitooligosaccharides.

In rice suspension culture, a large part (about 90% of total activity in the culture) of the chitinase activity was found in the medium. Two extracellular chitinases (which we named RCH-A and -B) were separated from the cell suspension by DEAE-cellulofine column chromatography. When cells were treated with N-acetylchitooligosaccharides (chitin oligosaccharides) for 3 days, extracellular chitinase activity increased about 3-fold over the control culture. After the treatment, another extracellular chitinase (named RCH-C) appeared in addition to increases in the levels of RCH-A and -B. Partial amino acid sequences of these enzymes indicated that RCH-A (33.5 kDa) and -B (34 kDa) were class Ib chitinases but RCH-C (27 kDa) was a class III chitinase. RCH-A and -B were capable of actively degrading water-insoluble chitin with high affinities, while RCH-C had less affinity for the substrate. However, when a water-soluble chitin derivative, 6-O-hydroxyethylchitin (glycolchitin) was used, RCH-C as well as RCH-A and -B degraded actively with a high affinity. A synergistic effect was observed when these three chitinases acted simultaneously in the hydrolysis of chitin.

Amino Acid Sequence↗
PubMed1996

Factors influencing survival following pulmonary resection for metastatic colorectal carcinoma.

The results of pulmonary resection and clinical factors relating to long-term survival were evaluated in 29 patients with histologically proven pulmonary metastasis from colorectal carcinoma. The patients were followed up from 4 months to 120 months, with an average of 43.7 months. Overall 5- and 10-year survival rates were 41% and 34% respectively. The 5- and 10-year survival rates in patients with metastatic nodules 30 cm or less in diameter were 77% and 58%, respectively, a significantly better result than in those with metastatic nodules over 30 mm in diameter. Survival in patients without nodal involvement was significantly better than that in patients with lymph node metastases. Multivariate analysis according to Cox proportional hazards model demonstrated that the size of the metastasis was an independent prognostic factor.

Adult↗
PubMed1996

Sex differences in the metabolism of (+)-S-145, a novel thromboxane A2 receptor antagonist in rat.

1. After the oral administration of 5 mg/kg S-1452 to rat, the plasma levels of (+)-S-145 were similar between the male and female, but there were sex differences in the profiles of its beta-oxidized and hydroxylated metabolites in plasma. 2. beta-Oxidation of (+)-S-145 determined in vitro was slightly higher in the female than in the male, and agreed with the plasma levels of the beta-oxidized metabolites. 3. 5-Hydroxylation activities of (+)-S-145 and beta-oxidized metabolites by rat liver microsomes were significantly higher in the male than in the female, but marked sex differences were not observed in 6-hydroxylation activities. These results revealed that differences in monooxygenase activities directly account for the sex differences in the plasma level of 5-hydroxylated metabolites, and that the peroxisomal beta-oxidation enzyme system also affected the plasma level of 6-hydroxylated metabolites. 4. Biliary excretion was higher in the male than in the female, and quantitative identification of metabolites in bile indicated that this was based on the prominent excretion of taurine conjugates in the male rat. This conclusion was supported by the fact that taurine conjugation activity was higher in male liver homogenates than in the female.

Animals↗
PubMed1996

New enzymatic assay for calcium in serum.

We established a simple and rapid kinetic assay for measurement of calcium in serum by using urea amidolyase (EC 3.5.1.45) from yeast species. The method is based on inhibition of the enzyme by calcium. In the assay, we eliminated endogenous ammonium ion by use of glutamate dehydrogenase (GLDH; EC 1.4.1.4); then in the presence of urea amidolyase, urea, ATP, bicarbonate, magnesium, and potassium ions, ammonium ion production was inversely proportional to calcium ion concentration in serum. The concentration of ammonium ion formed was determined by adding GLDH to produce NADP+ in the presence of 2-oxoglutarate and NADPH; we then monitored the change of absorbance at 340 nm. The within-run CVs of this method were 1.7-3.2% (n = 10) at 1.53-3.08 mmol/L, respectively. Day-to-day (total) CVs were 2.8-4.1%. Analytical recovery was 92-112%. The presence of other ions, ascorbic acid, reduced glutathione, bilirubin, hemoglobin, citrate, lipemic material, or human serum albumin did not affect this assay system. The correlation between values obtained with our method (y) and o-cresolphthalein complexone method (CPC) (x) was: y = 1.001x + 0.077 mmol/L (r = 0.949, Sy[symbol: see text]x = 0.079, n = 100); with the other enzymatic method (x) it was: y = 0.952x + 0.021 mmol/L (r = 0.955, Sy[symbol: see text]x = 0.074, n = 100). The SEs for each method were: 0.025 mmol/L, our method; 0.023 mmol/L, CPC method; and 0.025 mmol/L, the other enzymatic method.

Adenosine Triphosphate↗
PubMed1996

[Malignant mediastinal schwannoma associated with von Recklinghausen's disease--a resected case].

A case of malignant mediastinal schwannoma associated with von Recklinghausen's disease is reported. A 44-year-old woman was admitted to Chiba University Hospital because of an abnormal shadow on chest X-ray film. CT scan showed a cystic tumor in upper mediastinum and then tumor extirpation was performed. This cystic tumor was related to the sympathetic trunk and 60 x 35 x 33 mm in diameter. Its cut surface showed a thick irregular capsule and multilocular. Microscopic examination disclosed malignant cells with mitosis associated with neurofibroma. An immunohistochemical staining of these malignant cells with anti S-100 protein showed positive reaction. From these findings this tumor was diagnosed as malignant schwannoma. There is no evidence of recurrence two year after the operation. This is the first case of malignant schwannoma with cystic formation in Japan.

Adult↗
PubMed1996

[A nation-wide survey for neurologic and hepato-neurologic type of Wilson disease: clinical features and hepatic copper content].

A nation-wide survey for Wilson disease was performed from 1990 to 1991. We studied clinical features and copper content in liver for the neurologic and hepato-neurologic types. A questionnaire was sent to more than five thousand hospitals in Japan. Thirty-three percent of physicians completed the questionnaire. Four hundred and twenty-five cases were studied for the onset age, primary symptoms, prognosis and hepatic copper content. The onset age of neurologic and hepato-neurologic type of Wilson disease was usually 6 years or older. The most common initial symptom was dysarthria. Gait disturbance, flapping tremor and Kayser-Fleischer rings were also very common symptoms. We conclude that in patients with dysarthria and/ or extra pyramidal symptoms over 6 years of age, Wilson disease should be considered. The prognosis quod vitam of patients with neurologic and hepato-neurologic Wilson disease is not always fatal. However, many patients required prolonged treatment at either a hospital, sanatorium or at home due to irreversibility of their severe neurological defects. This result shows that early detection is the most important factor for a promising prognosis. Copper content in liver was examined for each type of Wilson disease. Neurologic type of Wilson disease had the highest copper content, followed by hepato-neurologic type. Hepatic type had the lowest copper level out of these three forms of the disease. The mechanism of onset for each type of Wilson disease should be studied using these results.

Adolescent↗
PubMed1996

[Usefulness of subcutaneous implantable port with new one-way valve].

Because of the development of the subcutaneous implantable port, intra-arterial infusion chemotherapy for malignant tumor has been performed in safety and it is now possible to choose a more effective method of drug administration. Many problems remain, however. In this study, we investigated the performance of subcutaneous implantable port with a new one-way valve with safety, septum intensity and a back stream of blood. This new port was very safe, with good septum intensity and water backflow. In the performance test with a back stream of water into the catheter, water did not back up into the catheter connecting with the port with the one-way valve, but did so without the one-way valve after releasing a load of 2,000 g from the septum. This suggests that the catheter obstruction is decreased by adding a one-way valve to the port.

Catheterization↗