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Biomedical subjects

H Ohta

Publications and source records attributed to H Ohta.

At least 523 records · Page 29Linked to original sources
PubMed1991

Expression of various sialylated carbohydrate antigens in malignant and nonmalignant pancreatic tissues.

The expression of six sialylated carbohydrate antigens (CA19-9, CA-50, SLEX, SLX, DU-PAN-2, ST-439) was examined in malignant and nonmalignant pancreatic tissues using an immunohistochemical method to elucidate the characteristics of these carbohydrate antigens as tumor markers. All carbohydrate antigens except for sialyl SSEA-1 (SLX, 52.4%) were expressed in more than 80% of the pancreatic cancer. CA19-9 and CA-50, belonging to type I blood group antigens, and DU-PAN-2 and ST-439 were localized predominantly in the cytoplasm of cancer cells, while sialyl Lex (SLEX) and SLX, belonging to type II blood group antigens, were stained mainly on the apical membranes of malignant glands. Although type I antigens were expressed in most nonmalignant pancreatic tissues, the type II antigens and ST-439 were absent in almost all of the normal tissues and faintly expressed in few chronic pancreatitis tissues, suggesting the high tumor specificity of these antigens. Each antigen was expressed on the apical surface of ducts in normal pancreas. However, in about 30% of chronic pancreatitis cases, type I antigens and DU-PAN-2 were observed in the cytoplasm of ductal cells. All patients showing stromal stain, possibly caused by loss of antigen polar expression and shedding into the surrounding stroma adjacent to malignant glands, revealed high levels of serum antigen. This finding suggests that the stromal appearance of antigens is a significant factor in the elevation of serum antigen levels.

Antibodies, Monoclonal↗
PubMed1991

A Lipoxygenase Pathway Is Activated in Rice after Infection with the Rice Blast Fungus Magnaporthe grisea.

Lipoxygenase (LOX) and lipid hydroperoxide-decomposing activity (LHDA) markedly increased in the fifth leaves of rice (Oryza sativa cv Aichiasahi) after infection with the rice blast fungus, Magnaporthe grisea. The increases in the enzyme activities were significantly higher in response to infection with an incompatible strain (race 131) compared with infection with a compatible strain (race 007) of the fungus. Using ion-exchange chromatography, we isolated three LOX activities (leaf LOX-1, -2, -3) from both uninoculated and infected leaves. The activity of leaf LOX-3, in particular, increased in the incompatible race-infected leaves. The leaf LOX-3 had a pH optimum of 5.0 and produced preferentially 13-l-hydroperoxy-9,11 (Z,E)-octadecadienoic acid (13-HPODD) from linoleic acid. 13-HPODD and 13-l-hydroxy-9,11 (Z,E)-octadecadienoic acid, one of the reaction products from 13-HPODD by LHDA, were highly inhibitory to the germination of conidia of the fungus. The present study provides correlative evidence for important roles of LOX and LHDA in the resistance response of rice against the blast fungus.

Journal Article↗
PubMed1991

Establishment and characterization of an epithelial cell line with quasi-normal chromosomes from a tubular adenoma of a familial polyposis coli patient.

An epithelial cell line designated FPCK-1 has been established from a tubular adenoma developing in a male familial polyposis coli (FPC) patient. The FPCK-1 cells grow very slowly with abundant mucus production and have been maintained stably for 3 years in culture. No growth was evident either in soft agar or nude mice. FPCK-1 cells present a normal male karyotype and do not show loss of specific loci on chromosomes 5, 17, 18, and 22 which have been reported to be lost frequently in human colon carcinomas. The cells have neither a point mutation on codon 12 of K-ras gene nor gene amplification of myc, c-H-ras, and/or c-K-ras genes. These results thus suggest the existence of hitherto unknown causative event(s) underlying adenoma development in FPC patients. The FPCK-1 cell line should prove useful for further analytical investigation of the multiple steps involved in human colon carcinogenesis.

Adenoma↗
PubMed1991

Solid phase peptide synthesis of human endothelin precursor peptides using two-step hard acid deprotection/cleavage methods.

Syntheses are described for the putative human and porcine biosynthetic precursors (hET-38 and pET-39) of endothelin, with the sequence previously deduced from human- and porcine-cDNA coding for preproendothelin. The Boc based solid phase synthetic method was applied, followed by weak hard acid, trimethylsilyl bromide, cleavage. The peptide removal from the resin was optimally accomplished with hydrogen fluoride. Disulfide bridges were formed by air-oxidation, and the linkage modes determined by enzymic (Endoproteinase Asp-N) digestion and HPLC. Five additional C-terminally elongated endothelin homologs were also synthesized. For alternative synthesis of pET-39, the use of trimethylsilyl trifluoromethanesulfonate for the removal of peptide from the resin generated a major side product, which was characterized. hET-38 was found to be less effective in vitro, when compared to endothelin. The vasoconstrictor activity in vitro of other related peptides was comparable to that of hET-38.

Amino Acid Sequence↗
PubMed1991

Aspartate and asparagine as electron acceptors for Wolinella recta.

Since fumarate and nitrate are not usually available in the oral ecosystem, it was investigated whether aspartate and asparagine could be used as alternative electron acceptors by Wolinella recta, which is strictly dependent on a respiratory metabolism with formate or H2 as electron donors. Both aspartate and asparagine were indeed shown to support growth of W. recta with formate as electron donor. Fermentative growth with aspartate alone was not possible. Succinate was the major end-product and was formed in equimolar quantities with respect to the amount of formate consumed. The consumption of aspartate and asparagine, on a molar basis, was 10-30% higher than that of formate. Cell-free extracts were prepared from cells grown with formate + fumarate, formate + aspartate, formate + asparagine, and formate + fumarate + aspartate. All these extracts contained high activities of asparaginase, aspartate ammonia-lyase and fumarate-reductase, but no significant activity of aspartate aminotransferase was detected, indicating that fumarate was synthesized directly from aspartate and subsequently reduced to succinate. Based on these results it seems likely that aspartate and asparagine can serve as natural electron acceptors for W. recta in periodontal lesions in which proteolytic bacteria abound.

Asparaginase↗
PubMed1991

Nuclease-sensitive binding of an Actinobacillus actinomycetemcomitans leukotoxin to the bacterial cell surface.

A leukotoxin of Actinobacillus actinomycetemcomitans 301-b was solubilized from cell-associated membrane vesicles by treatment with externally added DNase and RNase and was further purified by a procedure which included ammonium sulfate fractionation, gel filtration chromatography, and ion-exchange chromatography. The purified toxin had a molecular mass of 113,000 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a high isoelectric point (approximately 8.8). From these characteristics, it was to be expected that the membrane vesicle toxin was almost identical to the leukotoxin extracted with polymyxin B in an earlier study (C.-C. Tsai, B. J. Shenker, J. M. DiRienzo, D. Malamud, and N. S. Taichman, Infect, Immun. 43:700-705, 1984). The treatment with DNase and RNase was also highly effective for solubilizing the leukotoxin directly from whole cells, suggesting that the toxin is secreted extracellularly but retained in nucleic acids on the outermost surface of bacterial cells.

Aggregatibacter actinomycetemcomitans↗
PubMed1991

Peptide sequences for sucrose splitting and glucan binding within Streptococcus sobrinus glucosyltransferase (water-insoluble glucan synthetase).

The gene encoding glucosyltransferase responsible for water-insoluble glucan synthesis (GTF-I) of Streptococcus sobrinus (formerly Streptococcus mutans 6715) was cloned, expressed, and sequenced. A gene bank from S. sobrinus 6715 DNA was constructed in vector pUC18 and screened with anti-GTF-I antibody to detect clones producing GTF-I peptide. Five immunopositive clones were isolated, all of which produced peptides that bound alpha-1,6 glucan. GTF-I activity was found in only two large peptides: one stretching over the full length of the GTF-I peptide and composed of about 1,600 amino acid residues (AB1 clone) and the other lacking about 80 N-terminal residues and about 260 C-terminal residues (AB2 clone). A deletion study of the AB2 clone indicated that specific glucan binding, which is essential for water-insoluble glucan synthesis, was lost prior to sucrase activity with an increase in deletion from the 3' end of the GTF-I gene. These results suggest that the GTF-I peptide consists of three segments: that for sucrose splitting (approximately 1,100 residues), that for glucan binding (approximately 240 residues), and that of unknown function (approximately 260 residues), in order from the N terminus. The primary structure of the GTF-I peptide, deduced by DNA sequencing of the AB1 clone, was found to be very similar to that of the homologous protein from another strain of S. sobrinus.

Amino Acid Sequence↗
PubMed1991

Purification and properties of two membrane alkaline phosphatases from Bacillus subtilis 168.

Two alkaline phosphatases were extracted from the membranes of Bacillus subtilis 168 stationary-phase cells and purified as homogeneous proteins by hydroxyapatite column chromatography. Alkaline phosphatases I and II differed in several properties such as subunit molecular weight, substrate specificity, thermostability, Km, pH stability, and peptide maps.

Alkaline Phosphatase↗
PubMed1991

Cerebrovascular effects produced by electrical stimulation of fastigial nucleus.

We used the microsphere technique and laser flowmetry to assess cerebral blood flow in 43 anesthetized rats. Cerebral blood flow did not increase significantly when the fastigial nucleus was stimulated 15 min after administration of alpha-chloralose. In animals that received maintenance doses of alpha-chloralose, the modest (50%) increase in cerebral blood flow that did occur returned toward control during stimulation despite a continued stable elevation of arterial pressure. Stimulation of fastigial nucleus 2 h after alpha-chloralose elicited a 20 +/- 3 mmHg increase in arterial pressure; cerebral blood flow increased gradually for 30-60 s after the rise in arterial pressure and reached a peak that was approximately 90% (P less than 0.05) above baseline. The stimuli did not significantly reduce vascular resistance or impair autoregulation. We did not stimulate the fastigial nucleus for more than 2 h after administration of alpha-chloralose because anesthesia was effective for only 2 h. This study demonstrates that stimulation of the fastigial nucleus in rat produces a delayed increase in cerebral blood flow that is blocked by alpha-chloralose anesthesia. The delay in increases of cerebral blood flow suggests that a metabolic mechanism, not a direct neurogenic vascular effect, may account for increases in flow with fastigial stimulation.

Analysis of Variance↗
PubMed1991

Serum sialyl-Tn antigen levels in patients with digestive cancers.

Serum levels of sialyl-Tn antigen (STN) were measured using a one-step radioimmunoassay kit in 257 patients with digestive cancers, 121 patients with benign digestive diseases, and in 64 healthy controls. With 45 U/ml regarded as the cutoff value, the positive rates of serum STN in digestive cancers were as follows: pancreas 40.0%, stomach 28.1, colon and rectum 27.8, biliary tract 25.0, liver 7.1, and esophagus 0%. In benign digestive diseases, the positive rate of STN was low (4.1%). In gastric and colorectal cancers, simultaneous measurements of STN and carcinoembryonic antigen (CEA) revealed that the positive rates of STN, CEA, and STN and/or CEA were 28, 42, and 55%, respectively. There was no significant correlation between STN and CEA in these cancers. STN may be a useful serum marker for digestive cancers, especially gastric and colorectal cancers.

Antigens, Neoplasm↗
PubMed1991

Role of secretin in basal and fat-stimulated pancreatic secretion in conscious rats.

The role of endogenous secretin in basal and fat-stimulated pancreatic exocrine secretion was investigated in conscious rats. Rats were prepared with chronic fistulas draining bile and pancreatic juice, which was collected and returned to the duodenum at all times. Six days postoperative rats were fasted overnight, and pancreatic protein and fluid secretion were monitored for 3 h under basal conditions (0.15 M NaCl, intraduodenally) and during 2 h of intraduodenal infusion of a 20% triglyceride emulsion (Liposyn). Solutions were infused at 4.6 ml/h. Rats received a single bolus injection of 0.1 ml antisecretin serum or normal rabbit serum starting in the second hour of the basal period, and the effect on basal and fat-stimulated pancreatic protein and fluid secretion was determined. Antisecretin serum significantly inhibited basal interdigestive pancreatic protein and fluid secretion by 43% and 36%, respectively. Infusion of 20% fat emulsion stimulated a 2.1-fold increase in pancreatic protein and fluid secretion. The stimulation of both protein and fluid secretion was significantly inhibited by 60% by antisecretin serum. Plasma secretin after 2 h of fat infusion was 17.7 +/- 1.8 pM and was greatly reduced by the presence of secretin antiserum. The results support the hypothesis that secretin released by fatty acids is an important mediator of the pancreatic protein and fluid secretory response to dietary fat in the rat.

Animals↗
PubMed1991

Effects of pretreatment with basic fibroblast growth factor, epidermal growth factor and nerve growth factor on neuron survival and neovascularization of superior cervical ganglion transplanted into the third ventricle in rats.

Effects of short-term treatment with basic fibroblast growth factor (FGF), epidermal growth factor (EGF) and nerve growth factor (NGF) on neurite outgrowth of superior cervical ganglia (SCG) in culture or on neuron survival and neovascularization of SCG in a transplantation system were examined in rats. SCG were preincubated with FGF, EGF and/or NGF for 30 min and cultured with drug-free medium for 2 days. FGF or EGF neither promoted neurite outgrowth of SCG nor potentiated the NGF-induced neurite elongation in culture. In the transplantation study, SCG were exposed to these factors for 30 min and grafted into the third ventricle of adult rats for 14 days. Although pretreatment of NGF, FGF, EGF or the combination of NGF and EGF were not effective, there was better neuron survival in SCG grafts pretreated with 1 micrograms/ml NGF and 1 micrograms/ml FGF together. In addition, density of capillaries in these grafts was significantly greater than in the other group tested. These results suggest that the synergistic interaction between NGF and FGF cause rapid neovascularization, which can prevent neuron death after transplantation.

Analysis of Variance↗
PubMed1991

Effect of Panax ginseng on age-related changes in the spontaneous motor activity and dopaminergic nervous system in the rat.

Effects of Panax ginseng on the spontaneous motor activity and central dopaminergic systems in old rats were investigated and compared with those in young rats. Oral intake of a 1.8% water extract of Panax ginseng for four weeks produced an increase in spontaneous motor activity during the dark period in old rats, while it caused a decrease in the activity in young rats. After the intake of ginseng extract for five weeks, it caused a significantly low dopamine utilization in the daytime in the striatum of old rats, while it produced a high dopamine utilization in the structure of young rats. Concentrations of striatal dopamine D-2 receptors in old rats were significantly lower than that in young rats, although subchronic Panax ginseng did not affect the striatal D-1 and D-2 receptors of old rats. These results suggest that subchronic intake of ginseng extract inhibits the activity of nigro-striatal dopamine neurons in the daytime and activates spontaneous motor activity during the dark period in old rats, while it produces opposite effects in young rats.

Aging↗
PubMed1991

Working memory deficit in aged rats in delayed nonmatching to position task and effect of physostigmine on performance of young and aged rats.

Young (5 month) and aged (23 month) male rats were tested in delayed nonmatching to position task using a T-maze, and their ability of working memory retention was assessed over interrun intervals ranging between 5 and 300 sec. There were no significant age differences in pretest performance at 0 sec interval, but significant memory loss was observed in aged rats when tested with the interrun intervals. Physostigmine (0.1 and 0.2 mg/kg) improved this age-related decline in working memory in a dose-dependent manner, whereas the treatment slightly but not significantly improved the performance of young rats. These results suggest that the central cholinergic system in aged rats was functionally deteriorated and that stimulation of the system could enhance working memory retention in aged rats.

Aging↗
PubMed1991

Basal forebrain lesioned mice exhibit deterioration in memory acquisition process in step through passive avoidance test.

Effects of the basal forebrain (BF) lesion on memory and learning performances were investigated in mice. Eight-week-old male mice received bilateral BF lesion by delivering a radiofrequency current. From fifteen days after the surgery, the step through type passive avoidance task was performed daily for 10 days. Lesioned animals showed severe impairment in the acquisition process of this task, but not in the retention process. Ambulatory activity of the BF-lesioned mice did not differ from those of the control group, suggesting the observed learning impairment was not due to the alteration of motor activity. These results indicate that a memory impaired model mice can be successfully made by the radiofrequency lesion of bilateral BF neurons.

Animals↗
PubMed1991

Effects of transient cerebral ischemia in gerbils on working memory performance in the delayed nonmatching to position task using a T-maze.

To examine the working memory performance, gerbils were tested in the delayed nonmatching to position task using a T-maze, and the effects of cerebral ischemia on the performance were examined. There were no significant differences between gerbils and rats in the alternation performance without delay and with the interrun intervals ranging from 10 to 810 sec. These data suggest that this task is useful for assessing working memory in gerbils as well as in rats. Scopolamine (0.1 and 0.2 mg/kg) impaired the working memory performance in both species. Bilateral occlusion of the common carotid arteries for 5 min severely impaired the choice accuracy in the gerbils 1 to 3 days after the operation. This memory impairment was observed even at the shortest interval. One month after the operation, partial behavioral recovery was observed in the ischemic gerbils, in spite of a marked loss of the pyramidal cells in the hippocampus CA1 sector. These data indicate that the working memory performance is highly vulnerable to the cerebral ischemia and that the ischemic operation transiently but severely impairs the acquisition process of the working memory in gerbils.

Animals↗