Biomedical subjects

S Kanai

Publications and source records attributed to S Kanai.

At least 55 records · Page 3Linked to original sources

PubMed1998

Molecular cloning and characterization of the gene encoding N'-[(5'-phosphoribosyl)-formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (BBM II) isomerase from Arabidopsis thaliana.

We have isolated an Arabidopsis BBM II isomerase cDNA from an Arabidopsis cDNA library, by means of functional complementation of the E. coli hisA mutant strain HfrG6. The isolated cDNA encodes a polypeptide of 304 amino acids with a calculated molecular weight of 33,363. Sequence comparison with the HIS6 proteins of yeasts revealed that Arabidopsis BBM II isomerase contains an N-terminal extension of approximately 40 amino acids that shows the general properties of chloroplast transit peptides. This finding is consistent with the localization of other histidine biosynthetic enzymes, such as imidazoleglycerolphosphate dehydratase and histidinol dehydrogenase, in the chloroplasts in higher plants. The primary structure of the mature protein was 50% and 42% identical, respectively, to the HIS6 proteins of Schizosaccharomyces pombe and Saccharomyces cerevisiae, respectively, while no prominent sequence similarity to the bacterial BBM II isomerase was found. That the isolated Arabidopsis cDNA actually encodes a functionally active BBM II isomerase activity was confirmed in an in vitro enzyme assay using a crude extract prepared from strain HfrG6 transformed with the Arabidopsis BBM II isomerase cDNA.

Aldose-Ketose Isomerases↗

PubMed1998

Stem cell factor mRNA expression and production in human nasal epithelial cells: contribution to the accumulation of mast cells in the nasal epithelium of allergy.

BACKGROUND: In allergic rhinitis, mast cells are increased in number in the epithelium of the nasal mucosa and play an important role in the immediate response. However, the mechanism of the accumulation is not known. OBJECTIVE: The purpose of this study was to determine whether the nasal epithelial cells produce stem cell factor (SCF), the mast cell growth and chemoattractant factor, and contribute mast cell hyperplasia in the epithelium of allergic rhinitis. METHODS: We have characterized the cellular localization of SCF using immunohistochemistry, reverse transcribed-PCR, and ELISA; compared SCF production of cultured epithelial cells between patients with allergic rhinitis and nonallergic subjects; and compared the SCF production with the number of mast cells and the histamine content in the nasal epithelial scrapings. RESULTS: Immunohistochemically, SCF was identified in the nasal epithelium of the biopsy specimens and in cultured nasal epithelial cells. SCF mRNA was expressed by cultured nasal epithelial cells not only in patients with allergy but also in subjects with no allergy. However, the SCF/beta-actin mRNA ratio and SCF production in day 7 cultured epithelial cells was significantly higher in allergic than in nonallergic subjects (P =. 0424, P =.0085, respectively). SCF production from nasal scrapings in culture was strongly correlated with the number of mast cells (r = 0.506, P =.0023) and the histamine content (r = 0.480, P =.0040). CONCLUSIONS: These findings demonstrate that nasal epithelial cells produce SCF and may be important in the attraction, proliferation, and activation of mast cells in allergic inflammation in the nose.

Adolescent↗

PubMed1998

Adenylosuccinate synthetase genes: molecular cloning and phylogenetic analysis of a highly conserved archaeal gene.

Adenylosuccinate synthetase (PurA) catalyzes the first step in the de novo AMP synthesis and has been extensively studied in both Bacteria and Eukarya. We cloned the purA gene from the hyperthermophilic archaeon, Pyrococcus furiosus. The gene appears to be individually transcribed and encodes a protein of 339 amino acids. The amino acid sequence comparison with other archael PurAs found from recent genome analyses indicated that two deletions, one central and the other C-terminal, are a common feature of archaeal PurAs. None of the 21 PurA homologues analyzed from Eukarya and Bacteria exhibited this feature. Amino acid sequences of PurAs in Archaea showed 64% average identities which were significantly higher than the 50% and 55% calculated for Bacteria and Eukarya, respectively. Several residues conserved in PurAs of both Eukarya and Bacteria and shown to be of catalytic importance are missing in the archaeal PurAs. Phylogenetic analysis using PurA as the marker grouped life into 3 domains, hence it was consistent with results derived from 16-18S ribosomal RNA sequences. The topology within the three domains, in general, portrayed the hitherto accepted evolutionary relationship among the organisms utilized. PurA can, thus, serve as an additional marker to evaluate phylogenetic inferences drawn from sequence data from rRNA and other conserved genes. The presence of two unique deletions in both euryarchaeal and crenarchaeal PurAs, but not in those of Bacteria and Eukarya, is a strong evidence confirming the common lineage of these two subdomains of Archaea.

Adenylosuccinate Synthase↗

PubMed1998

Mechanism of the protective effects of sumac gall extract and gallic acid on the progression of CCl4-induced acute liver injury in rats.

To examine the mechanism of the preventive effect of tannins on the progression of carbon tetrachloride (CCl4)-induced acute liver injury in rats, sumac gall (SG) extract and gallic acid (GA) were used as substitutes for crude tannins, because SG is a kind of Chinese traditional medicinal herb containing large amounts of various tannins, and GA is one of the major constituents of SG. The protective effect of oral (p.o.) and intraperitoneal (i.p.) administration of each substance on progression of CCl4-induced hepatitis was investigated in rats. Speculating that the superoxide dismutase (SOD)-like activities (O2 radical-scavenging activities) and/or protective effects of these substances on cell membranes might play a key role in the mechanism opposing the progression of CCl4-induced hepatitis, the O2 radical-scavenging activities in liver cells and serum in rats were monitored. Both substances significantly prevented the progression of acute liver injury with both p.o. and i.p. administration. These findings suggest that the mechanism for this prevention might be due mainly to the protective effect of these substances on cell membranes rather than O2 radical-scavenging activities.

Acute Disease↗

PubMed1998

Inhibitory effect of central dopamine on basal pancreatic secretion in conscious rats.

We examined the role and the peripheral mechanism of action of central dopamine on basal pancreatic exocrine secretion in conscious rats. Rats were fitted with bile and pancreatic catheters to collect bile and pancreatic juice separately and also with a left lateral brain ventricle and external jugular vein catheters. After 90-min basal collection, the D1- and D2-receptor antagonists (Sch-23390 and eticlopride, respectively) and dopamine were administered into the lateral brain ventricle. Sch-23390 (30, 100, and 300 nmol/rat), but not eticlopride (300 nmol/rat), stimulated pancreatic fluid and protein secretion. Dopamine (30, 100, and 300 nmol/rat) inhibited pancreatic secretion lose dependently. Pretreatment with Sch-23390 prevented the inhibitory effect of dopamine. Intravenously injected Sch-23390 or dopamine had no effect on pancreatic secretion. The inhibitory effect of dopamine was blocked by bretylium, an inhibitor of norepinephrine release, and phentolamine, an alpha-blocker, but not by vagotomy. The beta-antagonist propranolol alone significantly inhibited basal pancreatic secretion, and dopamine did not modify the inhibitory effect of propranolol. The proton pump inhibitor omeprazole partially but not completely reduced the inhibition by dopamine. These results suggest that central dopamine inhibits pancreatic exocrine secretion via D1-like receptors and that the inhibitory effect is mediated via sympathetic nerves, especially alpha-adrenoceptors.

Animals↗

PubMed1998

Overexpression of cholecystokinin-B/gastrin receptor gene in the stomach of naturally occurring cholecystokinin-A receptor gene knockout rats.

We examined the cholecystokinin (CCK)-B/gastrin receptor, H+/K+-ATPase and somatostatin gene expression, the histology and immunohistochemistry of gastrin and somatostatin of the stomach, plasma gastrin levels, and gastric acid secretion in naturally occurring CCK-A receptor gene knockout (Otsuka Long-Evans Tokushima fatty, OLETF) rats. The CCK-B/ gastrin receptor, H+/K+-ATPase and somatostatin mRNAs were determined by Northern transfer analysis. The gastric acid secretion and the plasma gastrin level were measured in vivo. The levels of CCK-B/gastrin receptor mRNA in the forestomach and the glandular stomach in OLETF rats were 2-fold higher than those of control rats, although those of H+/ K+-ATPase and somatostatin mRNAs were not different. Histological examination revealed thickening of the fundic mucosa, and hyperplasia and hypertrophy of parietal cells, although immunohistochemistry of gastrin and somatostatin revealed no significant difference from the control rats. Gastric acid secretion stimulated by gastrin or histamine was enhanced, whereas the fasting plasma gastrin level was not significantly different from that in control rats. The overexpression of CCK-B/gastrin receptor mRNA and the hyperfunction of parietal cells were observed in rats without CCK-A receptor gene expression.

Animals↗

PubMed1998

Molecular phylogeny of zooxanthellate bivalves.

The aim of this research was to analyze the phylogenetic relationships of zooxanthellate bivalves belonging to the genera Tridacna, Hippopus, Fragum, and Corculum as well as to the closely related azooxanthellate bivalves belonging to Vasticardium and Fulvia. The small-subunit ribosomal RNA genes (18S rDNAs) from these bivalves were amplified by polymerase chain reaction with universal eukaryotic primers and were then sequenced. The sequence data from each species were analyzed by the neighbor-joining, maximum parsimony, and maximum likelihood methods, and phylogenetic trees were constructed. The results were essentially consistent with the morphological taxonomy of these bivalves. Thus, the zooxanthellate clams branch into two lineages, one composed of the genera Fragum and Corculum in the family Cardiidae, and the other composed of the genera Tridacna and Hippopus in the family Tridacnidae. However, present results indicate that the azooxanthellate clams analyzed (Vasticardium flavum and Fulvia mutica) are more likely to form a clade with the species of Tridacna and Hippopus than with those of Fragum and Corculum. This topology suggests that either the symbiosis with zooxanthellae occurred independently in each of two lineages, Tridacna-Hippopus and Corculum-Fragum, or the symbiosis was established in clams ancestral to the lineages of both the zooxanthellate clams and the azooxanthellate clams Vasticardium and Fulvia, and the latter lost the symbiotic relationship after the symbiotic clam lineages had diverged.

Animals↗

PubMed1997

Alpha- and beta-subunits of a V-type membrane ATPase in a hyperthermophilic sulfur-dependent archaeum, Thermococcus sp. KI.

The genes encoding alpha- and beta-subunits of a V-type ATPase in a sulfur-dependent hyperthermophilic archaeum, Thermococcus sp. KI, were cloned and sequenced. The deduced amino acid sequences were approximately 60, 50 and 25% identical to those of other archaeal, eukaryotic V-type and E. coli F-type ATPase, respectively. Phylogenetic analysis revealed that Thermococcus ATPase was closely related to that of Thermus, and those of Methanosarcina and Halobacterium.

Amino Acid Sequence↗

PubMed1997

Involvement of cholinergic processes in cholecystokinin (CCK) release [corrected] by luminal oleic acid.

Cholecystokinin (CCK) is an important bioactive peptide that stimulates pancreatic enzyme secretion. Circulating CCK is secreted from endocrine cells in the upper small intestine in response to various luminal stimuli and to vascular administration of gastrin releasing peptides. However, the mechanism of its release has not been fully elucidated. In the present study, the vascularly perfused duodenojejunum was isolated from male Wistar rats. The effects of luminal infusion of sodium oleate (2 or 0.4%) or intra-arterial infusion of neuromedin C(10(-7) M) with or without atropine and with a recently synthesized specific bombesin antagonist (EABI) were examined. The CCK release produced by intra-arterial infusion of neuromedin C was inhibited by EABI in a dose-dependent manner. The CCK release produced by luminal sodium oleate was inhibited by atropine, but not affected by EABI. The CCK release stimulated by luminal sodium oleate is mediated, at least in part, by a cholinergic mechanism, but neuromedin C directly stimulates CCK release via its receptor on CCK-producing cells.

Animals↗

PubMed1997

Molecular evolution of the photolyase-blue-light photoreceptor family.

The photolyase-blue-light photoreceptor family is composed of cyclobutane pyrimidine dimer (CPD) photolyases, (6-4) photolyases, and blue-light photoreceptors. CPD photolyase and (6-4) photolyase are involved in photoreactivation for CPD and (6-4) photoproducts, respectively. CPD photolyase is classified into two subclasses, class I and II, based on amino acid sequence similarity. Blue-light photoreceptors are essential light detectors for the early development of plants. The amino acid sequence of the receptor is similar to those of the photolyases, although the receptor does not show the activity of photoreactivation. To investigate the functional divergence of the family, the amino acid sequences of the proteins were aligned. The alignment suggested that the recognition mechanisms of the cofactors and the substrate of class I CPD photolyases (class I photolyases) are different from those of class II CPD photolyases (class II photolyases). We reconstructed the phylogenetic trees based on the alignment by the NJ method and the ML method. The phylogenetic analysis suggested that the ancestral gene of the family had encoded CPD photolyase and that the gene duplication of the ancestral proteins had occurred at least eight times before the divergence between eubacteria and eukaryotes.

Amino Acid Sequence↗

PubMed1997

Endoscopic transvesico-transurethral approach for repair of vesicovaginal fistula: initial case report.

Through an endoscopic transvesico-transurethral approach, we closed a vesicovaginal fistula that occurred after hysterectomy in a patient with uterine leiomyoma. The 3-mm fistula, located in the midportion of retrotrigone, was resected transurethrally and sutured in two layers through two 5-mm suprapubic trocars placed into the bladder and the urethral route under pneumobladder. The patient had no urine leakage from the vagina after surgery.

Cystoscopy↗

PubMed1997

Aging impairs release of central and peripheral cholecystokinin (CCK) in male but not in female rats.

BACKGROUND: Cholecystokinin (CCK) is an important bioactive peptide which stimulates pancreatic enzyme secretion and is also a neuromodulator in the central nervous system. We examined whether CCK release from the central and peripheral tissues was decreased in old animals, and whether there were sex-related differences. METHODS: Young (5-10-month-old) and old (25-29-month-old) male and female Wistar rats were used. Synaptosomes were prepared from the cerebral cortex, and the vascularly perfused duodenojejunum was isolated to examine central and peripheral CCK release, respectively. In some young female rats, 21 days after bilateral ovariectomy, the peripheral CCK release and the changes in CCK mRNA levels were examined. RESULTS: The central CCK release was impaired in response to the higher concentration of KCl, and the peripheral CCK response to the highest dose of neuromedin C was impaired in old male rats. However, no aging effect was observed in female rats, and ovariectomy did not affect CCK release or CCK mRNA level. CONCLUSIONS: CCK release from both central and peripheral tissues was decreased in old male rats, but not in old female rats.

Aging↗

PubMed1997

Presence of a novel hamster oral papillomavirus in dysplastic lesions of hamster lingual mucosa induced by application of dimethylbenzanthracene and excisional wounding: molecular cloning and complete nucleotide sequence.

A combination of 9,10-dimethyl-1,2-benzanthracene (DMBA) application and excisional wounding on the lingual tips of Syrian Golden hamsters (Mesocricetus auratus) induces dysplastic and malignant mucosal lesions. Papillomavirus genus-specific antigen and viral particles, measuring 55 nm in diameter, were demonstrated in the nuclei of squamous cells of dysplastic lesions showing koilocytotic change. In this study, we cloned a circular genome at a single Kpnl site from one of these dysplastic lesions. The genomic sequence of this clone, consisting of 7647 bp, was shown to be that of a novel papillomavirus with a conserved genomic organization. We named the new virus hamster oral papillomavirus (HOPV). All dysplastic lesions induced by this combination of DMBA application and excisional wounding contained viral DNA. Although Southern blot hybridization analysis could not detect the HOPV genome, PCR analysis demonstrated the latent HOPV genome in the tongue and skin of an untreated hamster. These results suggest that latently present HOPV genome is reactivated by the DMBA/wounding procedures. Lingual HOPV infection may be an important model for gaining insight into the interactions between papillomavirus infection, chemical carcinogens and physical irritations in carcinogenesis or malignant transformation.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1997

Efficacy of toki-shigyakuka-gosyuyu-syokyo-to (danggui-sini-jia-wuzhuyu-shengjiang-tang) on peripheral circulation in autonomic disorders.

To investigate the improvement in peripheral circulation in autonomic disorders, we monitored skin temperature in the tails of rats by thermography before and after the oral administration of boiled water extract of Toki-shigyakuka-gosyuyu-syokyo-to (TSGS-to). Oral administration of this extract elevated the temperature, calculated as the calories of radiant heat in the rat tail 5-10 min after uptake. The temperature elevation remained stable for more than 20 min. Calories were significantly reduced 60 min after uptake and almost returned to initial values 90 min later. Some of the constituent herbs, especially Angelicae radix, Cinnamomi cortex, Evodiae fructus, and Zingiberis rhizoma, appeared to be active in relieving hypothermia.

Administration, Oral↗

PubMed1997

Central somatostatin prevents vagal efferent nerve excitation produced by TRH but not by 2-deoxy-D-glucose.

Thyrotropin-releasing hormone (TRH) administered intracerebroventricularly and intravenous injection of 2-deoxy-D-glucose (2-DG) stimulate pancreatic exocrine secretion via vagal efferent nerve excitation. We examined whether centrally administered somatostatin would inhibit pancreatic exocrine secretion that was stimulated by vagal efferent nerve excitation in conscious rats. The animals were prepared with cannulas draining bile and pancreatic juice separately and with a duodenal cannula, a cerebroventricular cannula, and a right jugular vein cannula. Intracerebroventricular injection of somatostatin (0.4 or 4 nmol) significantly inhibited pancreatic secretion induced by TRH (50 or 500 pmol) in a dose-dependent manner. Intravenous injection of somatostatin had no effect on pancreatic secretion stimulated by TRH. On the other hand, somatostatin injected centrally did not affect pancreatic secretion induced by 2-DG (75 mg/kg) or basal secretion. These results suggest that TRH and 2-DG stimulate vagal efferent nerves via distinct mechanisms and that central somatostatin selectively inhibits excitation of the vagus induced by peptidergic (TRH) stimulation.

Animals↗

PubMed1996

An improved quantitative RT-PCR fluorescent method for analysis of gene transcripts in the STS-65 space shuttle experiment.

We describe a reverse transcription polymerase chain reaction (RT-PCR) technique using fluorescent dUTP to examine changes in mRNA level in samples. In this procedure, the amplified product is identified by the fluorescent detection system in an automated DNA sequencer, and if the MW of the DNA/RNA or the fluorescent dye is different, several samples can be analyzed in a single lane. The basis for this technique is similar to that of radiolabeled methods, and we applied this technique for the comparison of the expression level of the rat c-myc gene in osteoblasts exposed to microgravity and unit gravity conditions. Using the fluorescent- and radiolabeled methods, the level of rat c-myc mRNA were compared quantitatively and the results demonstrated that the c-myc expression level was not altered by microgravity. Therefore, this fluorescent RT-PCR technique is useful for gene expression analysis particularly when the samples are limited, such as in space flight experiments. The method also allows for rapid assessment of mRNA changes in many samples simultaneously.

Animals↗

PubMed1996

Leupeptin causes an accumulation of lipofuscin-like substances and other signs of aging in kidneys of young rats: further evidence for the protease inhibitor model of aging.

The "protease inhibitor model of aging" has been proposed on the basis of observations that young rat brains, livers, and retinas exposed to a protease inhibitor, leupeptin, accumulate lipofuscin-like substances (LLS) that are similar to age pigment, and also display a variety of other manifestations of aging. In order to validate this hypothesis in more general terms, the present study reports attempts to induce age-like changes in kidney cells of young rats. Male F-344 rats (4-5 weeks of age) were continuously infused intraperitoneally (i.p.) with various doses of leupeptin (1-50 mg/100 g/day) for 2 weeks. Control animals received saline solution and normal aged rats (27-30 months-old) received no treatment. Animals were sacrificed and subjected to histological examination. In kidneys of leupeptin-, but not saline-treated rats, generally round-shaped PAS-positive particles were clearly observed, which were predominantly distributed in proximal convoluted tubules, and which resembled particles in normal aged kidneys. With increasing drug doses, particles tended to become bigger and more numerous. The dominant accumulation of LLS in cells of the proximal convoluted tubules had a fine morphologic configuration that resembled age pigments in old rats. Also, there was a concomitant thickening of the basement membrane that was present in leupeptin-treated and aged kidneys, but not in controls. The results, therefore, support the protease inhibitor model of aging and provide an experimental tool for probing the cellular mechanisms of aging.

Aging↗

PubMed1996

Upregulation of antioxidant enzyme activities by deprenyl. Implications for life span extension.

In order to elucidate the exact role of antioxidant enzyme activities such as superoxide dismutase (SOD) in the aging process of animals, we compared various enzyme activities in different brain regions and in the liver of young (6-8 mo) and old (28-30 mo) Fischer-344 (F-344) rats. While Mn-SOD activities were elevated 3-5-fold in specific brain regions such as hippocampus, striatum and substantia nigra in brains of old male rats compared with the young, in females both forms of SOD (Cu, Zn- and Mn-) enzyme activities remained essentially unchanged with aging. Continued subcutaneous infusion of deprenyl for 3 weeks caused a 2-3-fold increase in activities of both Cu Zn- and Mn-SOD and a 50-60% increase in CAT activities in striatum and substantia nigra but not in hippocampus, cerebellum or the liver. Further, long-term treatment of old male rats with deprenyl caused a significant increase in the remaining life expectancy from 24 months of age by 34%. In conclusion, activities of antioxidant enzymes in these regions examined do not show any uniform age-associated change, suggesting that changes in these enzyme activities do not have any specific role in the life span of rodents in general terms. In contrast, the results of our deprenyl study suggests the possibility that the protection of catecholaminergic neurons by an upregulation of SOD and CAT activities plays a significant role in the life span of animals.

Animals↗