Biomedical subjects

H Hayashi

Publications and source records attributed to H Hayashi.

At least 127 records · Page 7Linked to original sources

PubMed2001

JC virus large T protein transforms rodent cells but is not involved in human medulloblastoma.

JC virus (JCV) together with Simian virus 40 (SV40) and BK virus (BKV), belong to the polyomavirus group and these viruses are neuro-oncogenic to rodents by expression of large T antigen (LT), which binds to cellular p53 and pRB thus reducing the anticancer potential of the cell. The function of LT has not been clarified because small t antigen (st) is transcribed from the same start codon as the overlapping reading frame of LT, and is translated as a different protein with the same N-terminal residues (1-81 amino acids) by a splice-site variant of mRNA. To elucidate the function of LT without st, we constructed plasmids that express LT only by deleting the splicing region including the C-terminus of st, and consequently stable cell lines were established that express only JCLT, SV40LT and BKLT. The growth rates of these cells were examined in colonies on soft agar and it was found that LT alone has a transforming capacity; the order of efficiency being SV40LT, BKLT and JCLT. In addition, to verify the involvement of JCV in human medulloblastoma, eight cases of medulloblastoma, six cases of frozen material and five cases of paraffin-embedded tissues which included three cases of frozen tissues, were examined. PCR assay, genomic Southern blotting, and in situ hybridization were applied to detect the JCV genome, and LT and st were examined by immunohistochemistry; the results were compared with JCV-infected tissues as a positive control. All methods failed to detect not only JCV genome but also LT protein in medulloblastoma and it was concluded that JCV LT has transforming activities in rodent cells, but is not related to human medulloblastoma.

3T3 Cells↗

PubMed2001

Low-grade pulmonary myxoid sarcoma of uncertain histogenesis.

The present report describes an unusual case of low-grade pulmonary sarcoma with extensive myxoid change in a 60-year-old man. During 30 months, the tumor enlarged gradually and thereafter rapidly to 9 cm. Preoperative biopsy and cytology gave negative results. The resected mass, located at the periphery of the right upper lobe, was well circumscribed and showed gelatinous without necrosis or hemorrhage. Histologically, the tumor was composed of slightly atypical, spindle-shaped or stellate cells, which were loosely distributed within a prominent myxoid stroma. Epithelial differentiation was not seen. Lacunar structures were occasionally evident, but no cartilaginous matrix was seen. Mitotic figures were infrequent. Immunohistochemistry failed to clarify the nature of the neoplastic cells except vimentin positivity. Histochemically, the myxoid ground substance was composed of hyaluronic acid and acid mucopolysaccharide. Electron microscopy revealed no specific differentiation other than aggregates of filaments, which were seen in a number of neoplastic cells. Flow cytometric analysis of the neoplastic cells revealed a diploid pattern. These findings indicated that the neoplasm was a low-grade myxoid sarcoma; however, a definite diagnosis could not be made. The tumor might have been a variant of extraskeletal myxoid chondrosarcoma, especially considering the histochemical results.

Biomarkers, Tumor↗

PubMed2001

Glutathione S-transferase Pi is a dopamine-inducible suppressor of dopamine-induced apoptosis in PC12 cells.

The finding that the neurotransmitter dopamine induces apoptosis in neurons implies the existence of a cellular mechanism by which dopaminergic neurons protect themselves from dopamine-induced apoptosis. By profiling the expression of a number of genes in differentiating PC12 cells which exhibit elevated levels of dopamine biosynthesis, we found that expression of glutathione S-transferase class Pi (GSTp) mRNA was selectively up-regulated. Interestingly, dopamine added to the culture medium of PC12 cells also augmented their expression of GSTp mRNA. Suppression of GSTp expression by transfection of its antisense expression vector augmented dopamine-induced apoptosis of PC12 cells. Conversely, overexpression of GSTp made the resultant PC12 transfectants highly resistant to dopamine-induced apoptosis. Transfection of the antisense or sense GSTp expression vectors also resulted in corresponding augmentation or suppression of dopamine-induced activation of cell-associated Jun-N-terminal kinase (JNK), which has been suggested to mediate dopamine-induced apoptosis in neuronal cells. These results indicate that GSTp is a dopamine-inducible suppressor of dopamine-induced apoptosis in PC12 cells, and suggest that this activity is exerted through inhibition of JNK activity.

Animals↗

PubMed2001

Adaptive cytoprotection mediated by prostaglandin I(2) is attributable to sensitization of CRGP-containing sensory nerves.

BACKGROUND & AIMS: The phenomenon by which the gastric mucosa is protected in response to mild irritants has been called adaptive cytoprotection, a mechanism believed to be related to production of endogenous prostaglandins (PGs). We tested whether PGs generated by mild irritant prevent injury through the release of calcitonin gene-related peptide (CGRP) from the sensory nerves using prostanoid receptor-knockout mice. METHODS: The stomach was doubly cannulated and perfused with 1 mol/L NaCl or 50% ethanol. CGRP levels in the perfusate were determined by enzyme immunoassay, and the injured area was estimated at the end of perfusion. RESULTS: Preperfusion with mildly hypertonic saline (1 mol/L NaCl) increased generation of gastric PGE(2) and PGI(2) and reduced ethanol-induced mucosal damage. Exposure of ethanol after 1 mol/L NaCl increased intragastric CGRP levels from 166 +/- 27 to 713 +/- 55 pg/2 min (n = 4, P < 0.05), and the protective action of 1 mol/L NaCl was inhibited by indomethacin treatment. CGRP antagonist blocked 1 mol/L NaCl-induced protective effect. Intragastric perfusion of 50% ethanol after administration of PGI(2), but not of PGE(2), increased CGRP levels. Application of 1 mol/L NaCl to IP receptor-knockout mice (IP(-/-)) did not elicit the protective effects seen in the wild-type on ethanol-induced gastric mucosal lesions. Protective effect of 1 mol/L NaCl was observed in EP3 receptor-knockout mice (EP3(-/-)). CGRP level during ethanol perfusion was not increased in IP(-/-) but was increased in EP3(-/-) and wild-type counterparts after preperfusion of 1 mol/L NaCl. CONCLUSIONS: These results indicate that the endogenous PGI(2) generated by 1 mol/L NaCl may have a protective role in gastric mucosal injury through enhancement of CGRP release from gastric mucosa. This mechanism may explain the adaptive cytoprotection observed after treatment with mild irritants.

6-Ketoprostaglandin F1 alpha↗

PubMed2001

Expression of cyclin-dependent kinase inhibitors in taste buds of mouse and hamster.

Taste buds are specialized epithelial cell clusters in the oral squamous cell epithelium. Although taste buds have been reported to renew rapidly, the mechanism of cell cycle control in these specialized structures remains unresolved. To clarify the cell cycle status and role of cyclin-dependent kinase inhibitors (CDKI) for cell cycle control in the taste buds, we analyzed cell proliferation activity using bromodeoxyuridine (BrdU) and Ki-67 immunostainings and the expression of the Cip/Kip family of CDKI (p21Cip1, p27Kip1, and p57Kip2) in the circumvallate papillae of mouse and hamster. BrdU-positive cells were detected in the basal layer of the oral epithelium. In the taste buds, Ki-67-positive cells were seen in the basal area, with only a very few positive cells in the taste buds. Both p21Cip1 and p27Kip1 positive cells were seen in the suprabasal layer of the non-gustatory oral epithelium. In the taste buds, stronger p27Kip1 staining was detected than in the non-gustatory epithelium. Western blotting analysis revealed that p27Kip1 was abundant in the mucosal tissues from circumvallate papillae. Thus, our study suggests that the taste bud cells except for basal cells are post-mitotic cells and that the cell cycle arrest associated with taste bud cell differentiation could be regulated predominantly by p27Kip1.

Animals↗

PubMed2001

Detection of gastric cancer by repeat endoscopy within a short time after negative examination.

BACKGROUND AND STUDY AIMS: Although a large number of patients are examined using endoscopy in order to identify gastric cancer, it is unclear how individuals should be managed after they are not diagnosed as having gastric cancer at the time of their initial examinations. This study was conducted to identify the group at high risk for gastric cancer who should be examined by repeat endoscopy within a short time after obtaining negative results. PATIENTS AND METHODS: The study involved 3672 patients who were not diagnosed as having gastric cancer by endoscopy in 1993, but underwent re-examination by gastroscopy between January 1994 and December 1996. RESULTS: Among these participants, 32 patients (0.9%) were diagnosed as having gastric cancer. The incidence of gastric cancer was 2.0% in participants aged 60 to 69 and 2.7% in those with marked atrophy of the gastric mucosa. Multivariate analysis showed that the odds ratios (OR) for patients aged 60 to 69 and those with marked atrophy of the gastric mucosa were 3.092 and 3.255 (P < 0.01), respectively. Gastric cancer was detected in 17.2 % of patients who were previously diagnosed as having gastric adenoma and in 2.2% of those who were previously diagnosed as having gastric ulcer. The ORs for participants with these gastric lesions detected by the initial examination were 49.417 and 5.259 (P < 0.01), respectively. CONCLUSIONS: Groups at high risk for gastric cancer were identified by the initial endoscopy, when two findings (gastric lesions, atrophy) and age were combined. We emphasize the importance of repeat endoscopic examination for patients who are aged 60 to 69 or have marked atrophy of gastric mucosa, even if no lesions are detected on initial endoscopy. If gastric adenoma or ulcer are detected, endoscopic examination should be likewise repeated or these lesions should be treated by endoscopy or by other means.

Adenocarcinoma↗

PubMed2001

Sequence heterogeneity of the ten rRNA operons in Clostridium perfringens.

We have cloned and sequenced rRNA operons of Clostridium perfringens strain 13 and analyzed the sequence structure in view of the phylogenesis. The organism had ten copies of rRNA operons all of that comprised of 16S, 23S and 5S rDNAs except for one operon. The operons clustered around the origin of replication, ranging within one-third of the whole genome sequence as it is arranged in a circle. Seven operons were transcribed in clockwise direction, and the remaining three were transcribed in counter clockwise direction assuming that the gyrA was transcribed in clockwise direction. Two of the counter clockwise operons contained tRNA(Ile) genes between the 16S and 23S rDNAs, and the other had a tRNA(Ile) genes between the 16S and 23S rDNAs and a tRNA(Asn) gene in the place of the 5S rDNA. Microheterogeneity was found within the rRNA structural genes and spacer regions. The length of each 16S, 23S and 5S rDNA were almost identical among the ten operons, however, the intergenic spacer region of 16S-23S and 23S-5S were variable in the length depending on loci of the rRNA operons on the chromosome. Nucleotide sequences of the helix 19, helix 19a, helix 20 and helix 21 of 23S rDNA were divergent and the diversity appeared to be correlated with the loci of the rRNA operons on the chromosome.

Base Sequence↗

PubMed2001

Masseter inhibitory reflex in amyotrophic lateral sclerosis.

OBJECTIVES: To elucidate underlying abnormalities of the masseter motor system in amyotrophic lateral sclerosis (ALS). METHODS: We recorded biphasic EMG suppressions of the masseter muscle (silent or inhibitory periods 1 and 2) after electrical stimulation of the mental nerve during maximum clenching of the teeth in 16 ALS patients and 15 healthy control subjects. We also examined the recovery cycle of the silent periods by delivering paired stimuli with an interstimulus interval of 250 ms. RESULTS: Silent period 1 in the patients was not significantly different from that in control subjects, whereas silent period 2 (as measured by its area on the graph) was increased in the patients, especially with exaggerated jaw jerk. Only two patients showed absence of silent period 2. The recovery cycle of silent period 2 in the subgroup of patients with exaggerated jaw jerk was significantly lower than the control value. CONCLUSIONS: The abnormalities of the masseter inhibitory reflex in ALS could be ascribable to involvement of the corticobulbar or corticoreticular tract projecting to the inhibitory interneurons mediating silent period 2.

Adult↗

PubMed2001

CHOP, a basic leucine zipper transcriptional factor, contributes to the antiproliferative effect of IL-1 on A375 human melanoma cells through augmenting transcription of IL-6.

Interleukin-1 (IL-1) inhibits the proliferation of A375 human melanoma cells. We have demonstrated previously that p38 mitrogen-activated protein kinase (MAPK) mediated the antiproliferative effect of IL-1 partially through the downregulation of activity and protein level of ornithine decarboxylase (ODC). In this study, we investigated the role of CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), one of the p38 MAPK target transcriptional factors. The mRNA level of CHOP was not affected by IL-1 treatment in A375-6 cells. Unexpectedly, CHOP was constitutively phosphorylated, and IL-1 or p38 MAPK inhibitor, SB203580, did not affect the phosphorylation level. However, A375-6 cells exhibited enhanced sensitivity to IL-1 by transfecting CHOP expression plasmid and reduced sensitivity to IL-1 by antisense CHOP mRNA expression plasmid. Furthermore, CHOP appeared to regulate positively IL-6 production at the transcriptional level. The experiments using CHOP muteins revealed that dimerization ability - but not p38 MAPK-dependent phosphorylation or DNA binding activity - is important for the IL-6 inducing activity of CHOP. These results indicate that CHOP contributes to the IL-1 growth-inhibitory signal through augmenting IL-6 production.

Adjuvants, Immunologic↗

PubMed2001

Studies on the molecular mechanism of the interactions between the cyanobacterial transcription factor, SmtB, and its recognition DNA sequences.

Tolerance to the heavy-metal ion stress in cyanobacterial cell is regulated by the transcriptional repressor SmtB that senses the Zn/Cd concentration in the cell. SmtB regulated the transcriptional level of class II metallothionein, SmtA. There are two recognition DNA sequences (Bbs1 and Bbs2) in the operator/promoter region of smtA gene. To clear the functional meaning of the presence of these two sequences, we have compared the affinities of native and point-mutated SmtBs to these two sites. We also have compared the sizes of the protein-DNA complexes being formed with these two sites. SmtB forms protein-DNA complex in an unique size with Bbs1, in three different sizes with Bbs2. We have further designed the modified Bbs1 and Bbs2 sequences, and the results obtained with these sequences indicate that the differences observed between the cases of Bbs1 and Bbs2 are caused by the presence of direct repeat sequence and the differences in the linker sequences.

Bacterial Proteins↗

PubMed2001

Interaction of gramicidin with lysophosphatidylcholine as revealed by calorimetry and fluorescence spectroscopy.

The effect of the interaction of gramicidin (GA) with lysophosphatidylcholine (LPC) on the change in lipid structure upon heat incubation was revealed by differential scanning calorimetry (DSC) and fluorescence spectroscopy. DSC showed a large endothermic transition in both pure LPC micelles and GA-containing LPC micelles after prolonged heat incubation at 70 degrees C. To elucidate this behavior, fluorescence spectra of 1-anilinonaphthalene-8-sulfonate embedded in LPC micelles were measured. About 40% of the resultant LPC micelles was found to be transformed into the interdigitated gel structures after prolonged heat incubation. On the other hand, intrinsic fluorescence spectra of GA-containing LPC micelles caused a blue-shift of the emission maxima with incubation time, suggesting that tryptophans near the C-terminus of GA moved into a more apolar environment. In addition, GA-containing LPC micelles caused quenching of fluorescence with incubation time, due to the interaction between GA molecules. To determine the location of GA in LPC membranes, surface pressure was measured using the mixed monolayers composed of GA and LPC. The result suggests that GA molecule is localized by interdigitating the C-terminal part of adjacent to acyl chain of LPC.

Anti-Bacterial Agents↗

PubMed2001

Thioredoxin-mediated reductive activation of a protein kinase for the regulatory phosphorylation of C4-form phosphoenolpyruvate carboxylase from maize.

The activity of phosphoenolpyruvate carboxylase (PEPC, EC4.1.1.31) for the C4 photosynthesis is known to be regulated mainly in response to light/dark transitions through reversible phosphorylation by a specific protein kinase (PK). PEPC-PK with an M(r) of 30 kDa was purified about 1.4 million-fold to homogeneity from maize leaves and characterized. The purified PEPC-PK was readily inactivated under mild oxidative conditions, but the activity could be recovered by dithiothreitol (DTT). The recovery by DTT was strongly accelerated by thioredoxin (Trx) from E. coli. Trxs of plant origin such as Trx-m from spinach chloroplast and Trx-h from rice cytoplasm were also effective. These results suggest the possibility of PEPC-PK being redox-regulated via Trx in vivo.

Carbon Dioxide↗

PubMed2001

Insulin inhibits coronary endothelial cell calcium entry and coronary artery relaxation.

Hyperinsulinemia is closely related to coronary artery disease. Endothelial cells are important for the control of vascular tone, and dysfunction of endothelial cells has been implicated in coronary artery disease. The direct effects of insulin on coronary endothelial cells are nonetheless unknown. In this study, the acute effects of high-dose insulin were investigated on agonist-induced intracellular Ca(2+) concentration ([Ca(2+)](i)) in porcine coronary endothelial cells and coronary relaxation. Bradykinin (10 n M ) and cyclopiazonic acid (100 microM), an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, provoked large increases in [Ca(2+)](i) in coronary endothelial cells. This increase was dose-dependently inhibited by a 10-min preincubation with high doses of insulin (10, 30, 100 mU/ml). Under Ca(2+)-free conditions, bradykinin and cyclopiazonic acid provoked transient, small increases in [Ca(2+)](i). These increases were not affected by pretreatment with insulin (100 mU/ml). Bradykinin (1, 10, 100, 1,000 n M ) and cyclopiazonic acid (10 microM) significantly relaxed porcine coronary artery rings precontracted with histamine (1 microM). The vasodilator effects of bradykinin and cyclopiazonic acid were dose-dependently inhibited by insulin. These acute effects were not observed at physiologic concentrations. Our data indicate that high-dose insulin inhibits agonist-induced Ca(2+) response in coronary endothelial cells and attenuates agonist-induced coronary vasodilatation. The study suggests that hyperinsulinemia might be associated with coronary artery disease via derangement of endothelial Ca(2+)-dependent functions.

Animals↗

PubMed2001

Genomic map of Clostridium perfringens strain 13.

A physical and genetic map of Clostridium perfringens strain 13 was constructed. C. perfringens strain 13 was found to have a 3.1-Mb chromosome and a large 50-kb plasmid, indicating that strain 13 has a relatively small genome among C. perfringens strains. A total of 313 genetic markers were mapped on the chromosome of strain 13. Compared with the physical and genetic map of C. perfringens CPN50, strain 13 had a quite similar genome organization, but with a large deletion (approximately 400 kb) in a particular segment of the chromosome. Among several toxin genes, a beta2 toxin gene that is a novel virulence gene in C. perfringens was found to be located on the 50-kb plasmid.

Bacterial Toxins↗

PubMed2001

Sole expression of laminin gamma 2 chain in invading tumor cells and its association with stromal fibrosis in lung adenocarcinomas.

Laminin-5 (LN-5), an important basement membrane (BM) protein consisting of laminin alpha3, beta3 and gamma 2 chains, has been suggested to be involved in tumor cell invasion and tissue repair. In this study, the distribution of the LN-5 subunits in atypical adenomatous hyperplasia (AAH) and different types of adenocarcinomas of the lung was examined by immunohistochemical analysis. In AAH and non-sclerosing, well-differentiated adenocarcinomas, the LN gamma 2 chain was frequently detected along with the continuous BMs. These BMs were also positive for both LN alpha3 and beta3 chains, suggesting that LN-5 had been deposited. In contrast, the cytoplasmic staining for the LN gamma 2 chain was frequently observed in tumor cells of sclerosing, well-differentiated adenocarcinomas, as well as of moderately and poorly differentiated adenocarcinomas, without any evidence of co-expression of the LN alpha3 and beta3 chains. This staining pattern of the LN gamma 2 chain was prominent in carcinoma cells invading into interstitial stroma and was associated with the formation of a central scar in the tumor tissues. These results suggest that the LN gamma 2 chain monomer could be an important indicator of progression of lung adenocarcinoma.

Adenocarcinoma↗

PubMed2001

Seaweed prevents breast cancer?

To investigate the chemopreventive effects of seaweed on breast cancer, we have been studying the relationship between iodine and breast cancer. We found earlier that the seaweed, wakame, showed a suppressive effect on the proliferation of DMBA (dimethylbenz(a)anthracene)-induced rat mammary tumors, possibly via apoptosis induction. In the present study, powdered mekabu was placed in distilled water, and left to stand for 24 h at 4 degrees C. The filtered supernatant was used as mekabu solution. It showed an extremely strong suppressive effect on rat mammary carcinogenesis when used in daily drinking water, without toxicity. In vitro, mekabu solution strongly induced apoptosis in 3 kinds of human breast cancer cells. These effects were stronger than those of a chemotherapeutic agent widely used to treat human breast cancer. Furthermore, no apoptosis induction was observed in normal human mammary cells. In Japan, mekabu is widely consumed as a safe, inexpensive food. Our results suggest that mekabu has potential for chemoprevention of human breast cancer.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2001

Iron accumulation in the liver of male patients with Wilson's disease.

OBJECTIVES: There is accumulating evidence that ceruloplasmin, a copper protein with ferroxidase activity, plays an important role in iron metabolism. The genetic disorder, aceruloplasminemia, can lead to tissue storage of iron as in hemochromatosis. Because most patients with Wilson's disease, a genetic copper toxicosis, have hypoceruloplasminemia, some could be affected by iron overload. METHODS: Four male patients with Wilson's disease were enrolled in this study of pre- and post-treatment iron metabolism. RESULTS: Pretreatment copper contents of the liver were high in all four male patients studied as diagnostic of Wilson's disease. Genetic analysis supported their clinical diagnosis of Wilson's disease without a background of hemochromatosis. Pretreatment serum ceruloplasmin levels were <20 mg/dl in all four patients. A standard penicillamine treatment for 3-8.5 yr further decreased their serum ceruloplasmin levels. Post-treatment serum ferroxidase activity was low as was the serum ceruloplasmin protein. Copper contents in the liver decreased after treatment in all subjects. In contrast, nonheme iron in the liver increased during treatment. Pretreatment liver specimens were positive for histochemical iron in two patients, and post-treatment specimens were positive in all four patients. In two patients, serum aminotransferase levels rebounded with elevation of serum ferritin concentration during the treatment period. Subsequent iron reduction by phlebotomy ameliorated their biochemical liver damage. CONCLUSION: Iron overload related to hypoceruloplasminemia may be clinically important, particularly in male patients with Wilson's disease.

Adolescent↗

PubMed2001

Anterior capsule contraction and intraocular lens decentration and tilt after hydrogel lens implantation.

AIM: To prospectively investigate changes in the area of the anterior capsule opening, and intraocular lens (IOL) decentration and tilt after implantation of a hydrogel IOL. METHODS: 100 patients underwent implantation of a hydrogel IOL in one eye and an acrylic IOL implantation in the opposite eye. The area of the anterior capsule opening, and the degree of IOL decentration and tilt were measured using the Scheimpflug videophotography system at 3 days, and at 1, 3, and 6 months postoperatively. RESULTS: The mean anterior capsule opening area decreased significantly in both groups. At 6 months postoperatively, the area in the hydrogel group was significantly smaller than that in the acrylic group. The mean percentage of the area reduction in the hydrogel group was also significantly greater than that in the acrylic group, being 16.9% in the hydrogel group and 8.8% in the acrylic group. In contrast, IOL decentration and tilt did not progress in either group. No significant differences were found in the degree of IOL decentration and tilt throughout the follow up period. CONCLUSIONS: Contraction of the anterior capsule opening was more extensive with the hydrogel IOL than with the acrylic IOL, but the degree of IOL decentration and tilt were similar for the two types of lenses studied.

Acrylic Resins↗