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Biomedical subjects

N Yamada

Publications and source records attributed to N Yamada.

At least 325 records · Page 18Linked to original sources
PubMed1997

cDNA cloning and differential gene expression of three catalases in pumpkin.

Three cDNA clones (cat1, cat2, cat3) for catalase (EC 1.11.1.6) were isolated from a cDNA library of pumpkin (Cucurbita sp.) cotyledons. In northern blotting using the cDNA-specific probe, the cat1 mRNA levels were high in seeds and early seedlings of pumpkin. The expression pattern of cat1 was similar to that of malate synthase, a characteristic enzyme of glyoxysomes. These data suggest that cat1 might encode a catalase associated with glyoxysomal functions. Furthermore, immunocytochemical analysis using cat1-specific anti-peptide antibody directly showed that cat1 encoding catalase is located in glyoxysomes. The cat2 mRNA was present at high levels in green cotyledons, mature leaf, stem and green hypocotyl of light-grown pumpkin plant, and correlated with chlorophyll content in the tissues. The tissue-specific expression of cat2 had a strong resemblance to that of glycolate oxidase, a characteristic enzyme of leaf peroxisomes. During germination of pumpkin seeds, cat2 mRNA levels increased in response to light, although the increase in cat2 mRNA by light was less than that of glycolate oxidase. cat3 mRNA was abundant in green cotyledons, etiolated cotyledons, green hypocotyl and root, but not in young leaf. cat3 mRNA expression was not dependent on light, but was constitutive in mature tissues. Interestingly, cat1 mRNA levels increased during senescence of pumpkin cotyledons, whereas cat2 and cat3 mRNAs disappeared during senescence, suggesting that cat1 encoding catalase may be involved in the senescence process. Thus, in pumpkin, three catalase genes are differentially regulated and may exhibit different functions.

Amino Acid Sequence↗
PubMed1997

Increased sialyl Lewis A expression and fucosyltransferase activity with acquisition of a high metastatic capacity in a colon cancer cell line.

A human colon cancer cell line, OCUC-LM1(LM), was established from a liver metastasis in our laboratory. Intrasplenic injection of LM into nude mice was repeated three and five times, and the daughter cell lines were designated as LM-H3 and LM-H5 respectively. The level of sialyl Lewis A (SLA) in the supernatant of LM-H3 and LM-H5 was 3 and 4.5 times higher than that of LM respectively. Flow cytometric analysis of SLA expression showed that the peak channel for LM was 113; for LM-H3, 126; and for LM-H5, 146. The mean fluorescence intensity of LM was 102.3 +/- 43.5; for LM-H3, 126.2 +/- 28.4; and for LM-H5, 144.8 +/- 23.4. In endothelial cell adhesion assays, the percentages of adherent LM-H3 and LM-H5 cells were significantly higher than for LM. The activity of alpha1-->4 fucosyltransferase was higher in LM-H3 and LM-H5 than in LM, but there was no difference in alpha2-->3 sialyltransferase activities for type 1 chain among the cell lines. Our results suggest that SLA expression is associated with acquisition of a high capacity for liver metastasis of colon cancer; increased SLA expression is due mainly to increased fucosyltransferase activity.

Animals↗
PubMed1997

Apolipoprotein E in progressive supranuclear palsy in Japan.

Progressive supranuclear palsy (PSP) is a rare neurodegenerative disease which shows several psychiatric and neurologic symptoms: pseudobulbar palsy, supranuclear ocular palsy, extrapyramidal rigidity, gait ataxia, and dementia. Almost all cases seem to be sporadic; therefore, the elucidation of risk factors is important to clarify the pathological mechanism. Apolipoprotein E4 (ApoE4) is now well established as a risk factor of Alzheimer's disease (AD). Here we report the ApoE allele frequency in PSP, which shares pathological findings such as neurofibrillary tangle (NFT) with AD. NFT is an important sign for the derangement of normal cytoskeletons in degenerating neurons. Although there was no significant increase in epsilon 4 allele frequency in the present series of PSP cases compared with that in the Japanese controls, there was a significant increase in the epsilon 2 allele frequency in PSP compared to controls.

Aged↗
PubMed1997

Effect of macrophage colony stimulating factor on the advanced atherosclerosis in Watanabe heritable hyperlipidemic rabbits.

We have reported that macrophage colony-stimulating factor (M-CSF) prevents atherosclerosis in young WHHL rabbits (Atherosclerosis 93:245, 1993). In the present study, we injected recombinant human M-CSF (250 micrograms/day) into WHHL rabbits aged 11 months 3 times a week after advanced atherosclerosis was established. After 8 months of treatment, we did not find any significant difference in plasma lipid levels, cholesterol ester content in the aorta or macroscopic atherosclerosis lesion area between M-CSF treated and non-treated rabbits. There was, however, a significant difference in the ratio of intimal to medial thickness (1.08 vs 1.7, p < 0.01). Thus, M-CSF may influence vascular smooth muscle cell function and modify the process of atherosclerosis in advance lesions.

Animals↗
PubMed1997

Apolipoprotein E accumulates with the progression of A beta deposition in transgenic mice.

To study the role of apolipoprotein E (apoE) in vivo in deposits of amyloid beta protein (A beta), a major component of senile plaque amyloid in the brain of patients with Alzheimer disease, the transgenic mice were examined by apoE immunostaining. The mice were systemically overexpressing signal peptide and 99 amino acid residues of the carboxy-terminal fragment of human amyloid beta protein precursor (betaAPP) under control of the powerful cytomegalovirus enhancer/chicken beta-actin promotor. A beta deposits appeared at 4 months and increased with aging in the acinar cells of the transgenic pancreas. Similarly, apoE deposits appeared in the pancreatic acinar cells at 4 months old. The number and size of apoE deposits increased with aging and correlated with the progression of A beta deposits. Interstitial macrophages labeled by apoE immunostaining appeared at 8 months after birth and their number increased with aging. On serial section of the pancreata of 24-month-old mice, approximately 70% of A beta deposits were labeled with the apoE antiserum. ApoE was detected in the highly insoluble formic acid fraction of the transgenic pancreas by an immunoblot study. The Northern blot study revealed no increase in synthesis of endogenous apoE mRNA. These findings indicate that apoE is closely related to progression of A beta deposits with aging and suggest that A beta deposition in the transgenic pancreas is similar to that in the senile plaque of Alzheimer brains. Therefore, our experimental system using transgenic mice will provide a useful tool to analyze the molecular mechanism of A beta deposition in association with apoE in vivo.

Aging↗
PubMed1997

Case report: interferon induced coma in Sheehan's syndrome.

A 54-year-old woman who was being treated with 10 million units (mu) of natural interferon (IFN)-alpha per day for chronic active hepatitis C at a local clinic, developed coma on the fourth day of treatment. On admission to Yamagata University Hospital, she was still in a state of semicoma with severe hyponatraemia (122 mEq/L) and hypochloraemia (89 mEq/L). After the administration of electrolytes, her condition improved remarkably. Endocrinological loading tests showed a hypofunction of the anterior pituitary gland. In consideration of these results, and her past experiences of haemorrhage during childbirth and subsequent amenorrhoea, we diagnosed her illness as a coma as a result of Sheehan's syndrome which had become overt during IFN therapy. She recovered completely after treatment with hydrocortisone and l-thyroxine.

Adrenocorticotropic Hormone↗
PubMed1997

Gastrointestinal autonomic nerve tumors: immunohistochemical and ultrastructural studies in cases of gastrointestinal stromal tumor.

The gastrointestinal autonomic nerve tumor (GAN tumor) is an uncommon stromal tumor with a morphological feature resembling the cell processes of the enteric plexus, and was originally termed a plexoma or plexosarcoma. Light microscopic studies show the GAN tumor most often consists of spindle-shaped cells indistinguishable from a smooth muscle tumor or Schwann cell tumor. Immunohistochemical and ultrastructural examinations of 18 cases of gastrointestinal stromal tumor (GIST) were performed. During ultrastructural examination, all of the 12 cases which were immunohistochemically positive for S-100 protein or neuron-specific enolase (NSE) showed synapse-like structures containing dense core neurosecretory granules measuring 100-200 nm, and 40-60 nm endocytoplasmic vesicles. These results suggest that most GIST of neurogenic origin are tumors derived from the myenteric nerve plexus.

Adult↗
PubMed1997

An insertion or deletion in the extramembrane loop connecting helices E and F of archaerhodopsin-1 affects in vitro refolding and slows the photocycle.

Upon addition of retinal, archaeopsin-1 expressed in Escherichia coli (ecaO-1002) regenerated the chromophore in dimyristoyl phosphatidylcholine (DMPC), 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) and sodium dodecyl sulfate (SDS) mixed micelles as efficiently as the same opsin prepared from halobacteria. Introduction of an insertion or a deletion of five amino acids into the surface loop connecting helices E and F changed the secondary and tertiary structures of ecaO-1002 in SDS, and diminished regeneration of the chromophore. The effect of the insertion and deletion on the in vitro refolding was specific to archaeopsin because the same insertion introduced at the corresponding position of bacterioopsin (bO) did not affect chromophore regeneration. The photocycle of the regenerated ecaR-1002 decreased in DMPC/CHAPS/SDS mixed micelles compared with that of aR-1 in the claret membrane, which was consistent with the reported behavior of bO. Unexpectedly, the insertion and deletion in loop EF perturbed the photocycle of the regenerated ecaR-1002. The accumulation of long-lived N- and O-like intermediates suggested that the insertion and deletion slowed down the proton uptake steps at the cytoplasmic surface.

Amino Acid Sequence↗
PubMed1997

Methylenetetrahydrofolate reductase polymorphism and pre-eclampsia.

A common missense mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, a C to T substitution at nucleotide 677, is responsible for reduced MTHFR activity and associated with modestly increased plasma homocysteine concentrations. Since underlying maternal vascular disease increases the risk of pre-eclampsia, we had the working hypothesis that pre-eclampsia patients would have an increased T677 allele frequency compared with controls. The MTHFR genotypes were determined in 67 pre-eclampsia patients, 98 normal pregnant women, and 260 healthy adults by the PCR/RFLP method. The T677 allele and the genotype homozygous for the T677 allele were significantly increased in the pre-eclamptic group compared with the controls (p < 0.02 and p < 0.004, respectively). The data indicate that the T677 variant of the MTHFR gene is one of the genetic risk factors for pre-eclampsia.

Adult↗
PubMed1997

Rhinovirus infection of primary cultures of human tracheal epithelium: role of ICAM-1 and IL-1beta.

Exacerbations of asthma are often associated with respiratory infection caused by rhinoviruses. To study the effects of rhinovirus infection on respiratory epithelium, a primary target for respiratory viruses, human rhinovirus (HRV)-2 and HRV-14 were infected to primary cultures of human tracheal epithelial cells. Viral infection was confirmed by showing that viral titers of supernatants and lysates from infected cells increased with time and by polymerase chain reaction. HRV-2 and HRV-14 infections upregulated the expression of intercellular adhesion molecule-1 (ICAM-1) mRNA, the major rhinovirus receptor, on epithelial cells, and they increased the production of interleukin (IL)-1beta, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha in supernatants. Antibodies to ICAM-1 inhibited HRV-14 infection of epithelial cells and decreased the production of cytokines after HRV-14 infection, but they did not alter HRV-2 infection-induced production ofcytokines. IL-1beta upregulated ICAM-1 mRNA expression and increased susceptibility to HRV-14 infection, whereas other cytokines failed to alter ICAM-1 mRNA expression. Furthermore, a neutralizing antibody to IL-1beta significantly decreased viral titers of supernatants and ICAM-1 mRNA expression after HRV-14 infection, but a neutralizing antibody to TNF-alpha was without effect. Immunohistochemical studies revealed that both HRV-14 infection and IL-1beta increased ICAM-1 expression on cultured epithelial cells. These findings imply that HRV-14 infection upregulated ICAM-1 expression on epithelial cells through increased production of IL-1beta, thereby increasing susceptibility to infection. These events may be important for amplification of airway inflammation after viral infection in asthma.

Antibodies↗
PubMed1997

A multicentre randomized controlled trial of recombinant interferon-alpha-2a in the treatment of patients with chronic hepatitis C.

Sixty-one chronic hepatitis C patients were randomly assigned to receive either 6 x 10(6) or 9 x 10(6) U of recombinant interferon-alpha-2a (IFN alpha-2a) six days a week for the first two weeks of treatment, followed in both cases by 6 x 10(6) U three days a week for the next 22 weeks. In the low dose group, 11 patients showed a complete response maintained for at least six months, 12 responded but then relapsed and nine did not respond; the corresponding figures in the high dose group were 10, 15 and five patients, respectively. The differences between groups are not statistically significant. Thus, this study provides no evidence of therapeutic benefit from increasing the initial dose of IFN alpha-2a. In both treatment groups, complete responders had significantly lower pretreatment viral titres than nonresponders and were significantly more likely to be infected by type 2a versus type 1b virus.

Alanine Transaminase↗
PubMed1997

Role of activin-A and follistatin in foam cell formation of THP-1 macrophages.

Macrophage (M phi) foam cell formation is a characteristic event that occurs in the early stage of atherosclerosis. To examine the roles of activin-A, a member of the transforming growth factor-beta superfamily, and follistatin, the binding protein for activin-A, in M phi function, we investigated their effects on foam cell formation of THP-1 M phi s. When THP-1 M phi s were treated with activin-A (5 nmol/L), foam cell formation and cellular cholesteryl ester accumulation were decreased. This downregulation was paralleled by a reduction in cell association and degradation of acetylated LDL. The inhibitory effect of activin-A on cell association and degradation was dose dependent, and the effect was blocked by concomitant addition of follistatin. Activin-A (5 nmol/L) also decreased the Bmax for acetylated LDL and scavenger receptor mRNA expression. Follistatin showed an effect opposite to that of activin-A and promoted M phi foam cell formation and cellular cholesteryl ester accumulation. It increased binding, cell association, and degradation of acetylated LDL and upregulated scavenger receptor mRNA expression. Because follistatin is the binding protein for activin-A, follistatin's effect is considered to be mediated by blocking the inhibitory effect of intrinsic activin-A. These results indicate that activin-A inhibits and follistatin promotes M phi foam cell formation by regulating scavenger receptor mRNA expression. We conclude that activin-A and follistatin play important roles in the process of atherosclerosis by regulating M phi foam cell formation.

Activins↗
PubMed1997

Skipping of exon 14 and possible instability of both the mRNA and the resultant truncated protein underlie a common cholesteryl ester transfer protein deficiency in Japan.

Among the Japanese population, a G-to-A mutation at the beginning of intron 14 of the human cholesteryl ester transfer protein (CETP) gene is a frequent cause of CETP deficiency characterized by markedly increased HDL cholesterol. The resulting abnormalities responsible for null CETP deficiency were studied in detail. The CETP mRNA transcripts amplified by polymerase chain reaction from the monocyte-derived macrophages of two homozygous patients were both found to be normal except for the whole deletion of exon 14. The deletion causes a shift of reading frame and introduces a premature termination codon downstream. Examination of the macrophage RNA from heterozygotes suggested the increased instability of the abnormal mRNA in the cytoplasm, because the amount of the aberrant transcript was nearly one third that of a normal transcript in the cytoplasm, while they were equal in the nucleus. Although this indicated the synthesis of a mutant CETP that lacks about 15% at its carboxy terminus, immunoblot analysis demonstrated that the abnormal CETP was virtually absent in both the media and cell lysates of transfected COS-1 cells, which massively expressed the mutant CETP mRNA. These results elucidate the primary abnormality due to the common CETP splicing mutation to be the exon skipping of mRNA, which decreases the level of mRNA and produces a truncated protein that should be rapidly degraded intracellularly.

Alternative Splicing↗
PubMed1997

Changes in blood coagulation, platelet aggregation, and lipid metabolism in rats given lipids containing docosahexaenoic acid.

In order to identify an adequate intake level of docosahexaenoic acid (DHA), changes in various parameters related to health benefits were studied in rats fed on diets containing 10% test lipids at different n-3(DHA)/n-6 ratios for two weeks. An evaluation of the critical level of the dietary n-3/n-6 ratio which had a significant effect on the parameters of several tissues indicated that the response to the dietary ratios differed according to the parameter, the variation in ratio ranging approximately from 0.20 to 1.77 with either a positive or negative effect on the health benefit. These results suggest that a suitable intake level of DHA would be within this range. In view of safety, however, the critical level for the dietary n-3/n-6 ratio may be around 0.56, as shown by a detailed analysis on the lower limit level of the harmful parameters. We thus propose that the dietary intake of DHA should not be more than 0.56 in terms of the n-3/n-6 ratio.

Animals↗
PubMed1997

An index predicting coronary heart disease: LDL/HDL x 5.

Atherosclerotic changes in the coronary artery are exacerbated by the balance between LDL, which carries cholesterol into the arterial wall, and HDL, which carries it out from the wall. The molecular weight of LDL is about 2 x 10(6) and that of HDL is about 4 x 10(5), which is almost 1/5 of the molecular weight of LDL. For this reason, LDL/HDL x 5 should be a good indicator of coronary heart disease. We evaluated this index in two subject groups. At first, we determined whether it could predict the incidence of effort angina in participants of a medical examination system. Most of the subjects were healthy and good candidates for primary prevention. LDL/HDL x 5 was a more sensitive index predicting effort angina than total cholesterol, LDL or HDL. The concentrations of HDL were significantly lower in myocardial infarction patients at all ages in both sexes. The average serum concentration of HDL was 56.6 +/- 15.0 mg/dl in the medical examination group and 38.9 +/- 12.2 mg/dl in the AMI group. We tested whether our new index, LDL/HDL x 5, could predict the incidence of re-infarction in patients with myocardial infarction who were candidates for secondary prevention. LDL/HDL x 5 was a more sensitive index predicting re-infarction than total cholesterol, LDL or HDL.

Aged↗
PubMed1997

Primary lymphoma of the heart, diagnosed antemortem.

Primary cardiac lymphomas diagnosed antemortem are extremely rare. We present a case of primary cardiac lymphoma initially diagnosed antemortem by cytologic examination of pericardial effusion fluid. Echocardiography suggested the presence of a tumor localized at the right ventricular free wall. The cytologic examination of pericardial effusion was effective in establishing the correct antemortem diagnosis.

Aged↗