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Biomedical subjects

Hiroshi Hara

Publications and source records attributed to Hiroshi Hara.

At least 19 recordsLinked to original sources
PubMed2003

Ingestion of water-soluble soybean fiber prevents osteopenia and hypercholesterolemia induced by ovariectomy in rats.

This study examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on intestinal calcium (Ca) absorption, bone mineral content, and serum total cholesterol levels using female Sprague-Dawley rats (5 weeks old) with or without ovariectomy (OVX). The rats in each group were fed a WSSF (50 g/kg of diet) or WSSF-free diet for 4 weeks. Ca absorption was higher in OVX rats fed the WSSF diet than in OVX rats fed the WSSF-free diet. Femoral Ca content in both sham and OVX rats fed the WSSF diet was higher than that in rats fed the WSSF-free diet. The serum total cholesterol levels were elevated after OVX compared with that in the sham rats, and this elevation was prevented by the WSSF diet. In conclusion, ingestion of WSSF prevented osteopenia and hypercholesterolemia induced by ovariectomy in rats.

Animals↗
PubMed2003

Establishment of mouse embryonic fibroblast cell lines that promote ex vivo expansion of human cord blood CD34+ hematopoietic progenitors.

The development of culture systems that facilitate ex vivo maintenance and expansion of transplantable hematopoietic progenitor cells (HPC) is vital to stem cell transplantation. The use of a monolayer of stromal cells on which to grow HPC in direct contact allows high efficiency ex vivo expansion of HPC. Here, we report an establishment of three murine embryonic fibroblast stromal cell lines from adherent cells of day-12 mouse embryos. Among them, HYMEQ-5 was most efficient in supporting long-term maintenance of human umbilical cord blood (CB) CD34(+) cells. Human CB CD34(+) cells cultured on HYMEQ-5 in the presence of stem cell factor (SCF), thrombopoietin, and flk-ligand (FL) showed high expansion of CD34(+)CD38(-) cells and highly proliferative potential-colony forming cells (HPP-CFC). Direct cell-to-cell contact between CD34(+) cells and HYMEQ-5 was important for this expansion. RT-PCR analysis showed that HYMEQ-5 produced FL, SCF, interleukin-6, and macrophage colony-stimulating factor (M-CSF). Expanded CB CD34(+) cells efficiently reconstituted hematopoiesis in nonobese diabetic/severe combined immunodeficient disease (NOD/SCID) mice. These findings suggest that HYMEQ-5 provides a milieu that supports long-term human hematopoiesis as well as ex vivo expansion of human CB CD34(+) HPC. This cell line may facilitate elucidation of the mechanism of cellular interactions between HPC and stromal cells.

Animals↗
PubMed2003

Soybean beta-conglycinin peptone suppresses food intake and gastric emptying by increasing plasma cholecystokinin levels in rats.

Cholecystokinin (CCK) is an important physiologic mediator that regulates satiety and gastric emptying. We demonstrated previously that soybean peptone acts directly on rat small intestinal mucosal cells to stimulate CCK release. In the present study, we examined the effects of beta-conglycinin, a major component of soy protein, and its peptone on food intake and gastric emptying after an intraduodenal infusion of beta-conglycinin peptone in relation to CCK release and interaction with the mucosal cell membrane. Intraduodenal infusion of beta-conglycinin peptone inhibited food intake in a dose-dependent manner, but that of whole soy peptone or camostat did not. The suppression of food intake by beta-conglycinin peptone was abolished by an intravenous injection of devazepide, a selective peripheral CCK receptor antagonist. The beta-conglycinin peptone infusion strongly suppressed gastric emptying with marked increases in portal CCK levels. We also observed that the beta-conglycinin peptone dose dependently and more potently stimulated CCK release from isolated dispersed mucosal cells of the rat jejunum than did beta-conglycinin itself. This stimulation corresponded to the binding activity of the peptide or protein to solubilized components of the rat jejunum membrane as evaluated by surface plasmon biosensor. These results indicate that beta-conglycinin peptone suppresses food intake, and this effect may be due to beta-conglycinin peptone in the lumen stimulating endogenous CCK release with direct acceptance to the intestinal cells.

Animals↗
PubMed2003

Ingestion of water-soluble soybean fiber prevents gastrectomy-induced iron malabsorption, anemia and impairment of voluntary running exercise performance in rats.

We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber, on gastrectomy-induced iron malabsorption, anemia and impairment of exercise performance in rats in two separate experiments. The study was designed as a 2 x 2 factorial arrangement with operation (total gastrectomy) and diet (WSSF) under sedentary (Experiment 1) and exercised (Experiment 2) conditions. In Experiment 1, gastrectomy reduced net iron absorption, hemoglobin concentration, hematocrit and hemoglobin regeneration efficiency (P < 0.01). However, in rats fed a WSSF diet (50 g/kg diet), iron absorption and the hematological variables of the gastrectomized rats were comparable to those in the sham-operated rats, demonstrating that ingestion of WSSF promotes iron absorption and prevents anemia after gastrectomy. Feeding WSSF increased pools of organic acids and soluble iron in cecal contents and decreased the pH of the cecal contents (P < 0.001). Of the many cecal variables measured, net iron absorption in gastrectomized rats was most closely correlated (r = 0.614, P < 0.01) with the short-chain fatty acid pool in the cecum. Cecal fermentation of WSSF may contribute to improvements in gastrectomy-induced nutritional defects. In Experiment 2, we examined voluntary running exercise performance in totally gastrectomized rats fed diets with or without WSSF. Total gastrectomy severely impaired running performance (P < 0.001), and WSSF feeding largely restored the lowered performance. We conclude that feeding WSSF improves anemia and impaired voluntary running performance in totally gastrectomized rats.

Anemia, Iron-Deficiency↗
PubMed2003

The addition of soybean phosphatidylcholine to triglyceride increases suppressive effects on food intake and gastric emptying in rats.

The physiologic roles of dietary lecithin have not yet been clearly defined. We examined the effects of soybean lecithin on gastric emptying (Experiments 1 and 2) and food intake (Experiment 3) in rats. Male Wistar rats were fed 2 g of a 20 g lipid/100 g diet containing various levels of lecithin after 24 h of food deprivation; gastric contents were collected 3 h after feeding (Experiment 1). In Experiment 2, the effects of lecithin and a CCK-A receptor antagonist on gastric emptying were examined using a modified phenol red recovery technique. In Experiment 3, their effects on food intake were examined after an intraduodenal infusion of an oil emulsion containing 50 mg soybean oil (SO) or SO partially replaced by lecithin (14-50%). Gastric emptying rates of the lipid and protein in the test diet (Experiment 1) or of phenol red (Experiment 2) were lower in the groups administered lecithin. Food intake for 60 min was lower in rats infused with the oil emulsion containing lecithin (25, 50%) than in rats not administered lecithin. The suppressive effects of lecithin on gastric emptying and food intake were largely reduced by devazepide. These results demonstrate that oil containing lecithin inhibits gastric emptying and food intake, and the effects are associated in part with CCK release.

Animal Feed↗
PubMed2002

Identification and characterization of the Escherichia coli envC gene encoding a periplasmic coiled-coil protein with putative peptidase activity.

PM61 is a chain-forming envC strain of Escherichia coli with a leaky outer membrane. It was found to have an oversized penicillin-binding protein 3, which was the result of an IS4 insertion in the prc gene. The other properties of PM61 were caused by the envC mutation. We cloned the envC (yibP) gene and identified the mutation site, causing a single residue substitution, H366Y, in the PM61 envC allele. The gene product was predicted to be a periplasmic protein having coiled-coil structure in the N-terminal region and homology to lysostaphin in the C-terminal region. Overexpression of envC inhibited cell growth, and overexpression of the PM61 mutant allele caused cell lysis. Disruption of the chromosomal envC caused the same defects as the envC point mutation, indicating the gene is dispensable for growth but important for normal septation/separation and cell envelope integrity.

Alleles↗
PubMed2002

Sugar alcohols enhance calcium transport from rat small and large intestine epithelium in vitro.

We compared the effect of a variety of sugar alcohols on calcium absorption from the rat small and large intestine in vitro. An Ussing chamber technique was used to determine the net transport of Ca across the epithelium isolated from the jejunum, ileum, cecum, and colon of rats. The concentration of Ca in the serosal and mucosal Tris buffer solution was 1.25 mM and 10 mM, respectively. The Ca concentration in the serosal medium was determined after incubation for 30 min and the net Ca absorption was evaluated. The addition of 0.1-200 mM erythritol, xylitol, sorbitol, maltitol, palatinit, or lactitol to the mucosal medium affected net Ca absorption in the intestinal preparations. Differences in Ca transport were observed between portions of the intestine, but not between sugar alcohols tested. We concluded that sugar alcohols directly affect the epithelial tissue and promote Ca absorption from the small and large intestine in vitro.

Animals↗
PubMed2002

A developmental biological study of aldolase gene expression in Xenopus laevis.

We cloned cDNAs for Xenopus aldolases A, B and C. These three aldolase genes are localized on different chromosomes as a single copy gene. In the adult, the aldolase A gene is expressed extensively in muscle tissues, whereas the aldolase B gene is expressed strongly in kidney, liver, stomach and intestine, while the aldolase C gene is expressed in brain, heart and ovary. In oocytes aldolase A and C mRNAs, but not aldolase B mRNA, are extensively transcribed. Thus, aldolase A and C mRNAs, but not B mRNA, occur abundantly in eggs as maternal mRNAs, and strong expression of aldolase B mRNA is seen only after the late neurula stage. We conclude that aldolase A and C mRNAs are major aldolase mRNAs in early stages of Xenopus embryogenesis which proceeds utilizing yolk as the only energy source. aldolase B mRNA, on the other hand, is expressed only later in development in tissues which are required for dietary fructose metabolism. We also isolated the Xenopus aldolase C genomic gene (ca. 12 kb) and found that its promoter (ca. 2 kb) contains regions necessary for tissue-specific expression and also a GC rich region which is essential for basal transcriptional activity.

Amino Acid Sequence↗
PubMed2002

Increased expression of interleukin-18 receptor on T lymphocytes in patients with acute graft-versus-host disease after allogeneic bone marrow transplantation.

Acute graft-versus-host disease (aGVHD), a potentially fatal side effect of allogeneic bone marrow transplantation (BMT), is initiated by the action of donor-derived T lymphocytes. We have shown previously that aGVHD is associated with elevated serum levels of interleukin-18 (IL-18). In this study, we analyzed the expression of the IL-18 receptor (IL-18R) on T lymphocytes of BMT patients with aGVHD. Flow cytometric analysis showed that in healthy subjects, a small population of CD4+ T cells expressed IL-18Ralpha, whereas a relatively large population of CD8+ T cells expressed IL-18Ralpha. In aGVHD patients, there were marked increases in the proportion of CD4+ or CD8+ T cells that express IL-18Ralpha. RT-PCR assays showed elevation of IL-18Ralpha and IL-18Rbeta mRNA levels in CD8+ T cells in aGVHD patients. These findings suggest that the expression of IL-18R is upregulated in T cells in patients with aGVHD and that the IL-18/IL-18R system is active during aGVHD.

Acute Disease↗
PubMed2002

Supplemental feeding of difructose anhydride III restores calcium absorption impaired by ovariectomy in rats.

In three separate experiments, we examined the effects of feeding difructose anhydride III (DFAIII) on intestinal calcium (Ca) absorption using female Sprague-Dawley rats (6 wk old) with or without ovariectomy (OVX). In Experiment 1, we showed that Ca absorption was lower in OVX rats fed the 2.0 and 3.0 g Ca/kg diets, but not the 1.0 g Ca/kg diet, than in sham-operated rats during a 3-wk test period. In Experiment 2, we demonstrated that Ca absorption rate in sham and OVX rats fed a diet containing 3% DFAIII was higher than that in rats fed a DFAIII-free diet 4 wk after consuming the test diets. Absorptive activities of everted sacs of the colon, but not of the duodenum, in rats fed DFAIII diet for 4 wk were higher than those in rats fed the control diet. In Experiment 3, we determined which of the small and large intestines is responsible for the effects of DFAIII on Ca absorption using OVX rats with cecocolonectomy or transsection and reanastomosis (sham). Both the sham and cecocolonectomized rats were divided into four subgroups and fed a control, polyethylene glycol (PEG), 1.5% DFAIII or 3% DFAIII diet. We set up the PEG group as another control group to observe the effects of shortening transit time of the small intestine in the DFAIII groups. Promotive effects of DFAIII on Ca absorption were abolished by cecocolonectomy. However, in the cecocolonectomized rats, the Ca absorption rate was still higher in the 1.5 and 3% DFAIII groups than in the PEG group. In conclusion, ovarian hormone deficiency impaired Ca absorption, but the reduction of Ca absorption was restored by feeding DFAIII.

Animals↗
PubMed2002

Melibiose, difructose anhydride III and difructose anhydride IV enhance net calcium absorption in rat small and large intestinal epithelium by increasing the passage of tight junctions in vitro.

An Ussing chamber technique was used to determine the effects of three indigestible disaccharides on net Ca transport from the luminal side to the basolateral side of isolated preparations of jejunal, ileal, cecal and colonic epithelium in rats. Permeability of Lucifer Yellow (LY) and transepithelial electrical resistance (TEER), which are indicators of intercellular passage of the intestinal mucosa, were also determined. The concentrations of Ca in the serosal and mucosal media were 1.25 mmol/L and 10 mmol/L, respectively. After a 30-min incubation, the net Ca transport, LY passage and TEER were determined. In the control experiment, LY permeability was lowest, and TEER value was highest in the colon. The addition of 1-100 mmol/L melibiose, difructose anhydride (DFA)III, or DFAIV to the mucosal medium increased the net Ca absorption and LY permeability dose-dependently in the jejunum, ileum, cecum and colon preparations. Melibiose decreased TEER dose-dependently in the jejunum and cecum, but not in the ileum and colon. DFAIII decreased TEER dose-dependently in the jejunum, cecum and colon, but not in the ileum. DFAIV decreased TEER dose-dependently in all four intestinal portions. Positive linear relationships were found between net Ca transport and LY passage in all portions of the intestine, whereas negative linear relationships were found between net Ca absorption and TEER. We concluded that the three indigestible saccharides directly affect the epithelial tissue and activate the passage of tight junctions, thereby promoting Ca absorption in the small and large intestine in vitro.

Animals↗
PubMed2002

Envelope disorder of Escherichia coli cells lacking phosphatidylglycerol.

Phosphatidylglycerol, the most abundant acidic phospholipid in Escherichia coli, is considered to play specific roles in various cellular processes that are essential for cell viability. A null mutation of pgsA, which encodes phosphatidylglycerophosphate synthase, does indeed confer lethality. However, pgsA null mutants are viable if they lack the major outer membrane lipoprotein (Lpp) (lpp mutant) (S. Kikuchi, I. Shibuya, and K. Matsumoto, J. Bacteriol. 182:371-376, 2000). Here we show that Lpp expressed from a plasmid causes cell lysis in a pgsA lpp double mutant. The envelopes of cells harvested just before lysis could not be separated into outer and inner membrane fractions by sucrose density gradient centrifugation. In contrast, expression of a mutant Lpp (LppdeltaK) lacking the COOH-terminal lysine residue (required for covalent linking to peptidoglycan) did not cause lysis and allowed for the clear separation of the outer and inner membranes. We propose that in pgsA mutants LppdeltaK could not be modified by the addition of a diacylglyceryl moiety normally provided by phosphatidylglycerol and that this defect caused unmodified LppdeltaK to accumulate in the inner membrane. Although LppdeltaK accumulation did not lead to lysis, the accumulation of unmodified wild-type Lpp apparently led to the covalent linking to peptidoglycan, causing the inner membrane to be anomalously anchored to peptidoglycan and eventually leading to lysis. We suggest that this anomalous anchoring largely explains a major portion of the nonviable phenotypes of pgsA null mutants.

Anti-Bacterial Agents↗
PubMed2002

Suppression of intestinal crypt cell proliferation and aberrant crypt foci by dietary quercetin in rats.

Quercetin inhibits proliferation of human gastric and colonic cancer cells in vitro by suppressing mitosis and increasing apoptosis. Quercetin might therefore act as an anticarcinogen in the alimentary tract, but previous findings have been inconsistent. We fed rats quercetin at dietary concentrations of 1, 5, 20, and 50 g/kg. At < or = 20 g/kg, we observed a statistically significant reduction in the frequency of crypt cell mitosis in proximal, mid, and distal small intestine and in distal colon, amounting to approximately 40% of control at 1 g/kg. There was no effect on apoptosis. Quercetin metabolites, but not quercetin aglycone, were detected in plasma of rats fed quercetin at 20 and 50 g/kg. In a second experiment, rats were fed quercetin at 1 g/kg after treatment with 1,2-dimethylhydrazine to induce aberrant crypt foci. In dimethylhydrazine-treated and control rats, crypt cell mitosis was suppressed at 48 h and 42 days after injection, and there was a statistically significant reduction in the number of aberrant crypts and larger aberrant crypt foci (> 4 crypts/focus) in the distal colon of treated animals. These findings demonstrate that quercetin can inhibit intestinal crypt cell proliferation in vivo, but the effect diminishes as the level of dietary exposure increases. At low concentrations, dietary quercetin inhibits induction of aberrant crypts by a mechanism that does not involve increased crypt cell apoptosis.

1,2-Dimethylhydrazine↗
PubMedDate not supplied

Ingestion of water-soluble soybean fiber improves gastrectomy-induced calcium malabsorption and osteopenia in rats.

OBJECTIVE: Total gastrectomy produces calcium malabsorption and osteopenia. We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber with low viscosity, on calcium absorption and bone characteristics in totally gastrectomized rats. METHODS: Male Sprague-Dawley rats were assigned to two groups: sham operation and gastrectomy. After the postoperative recovery period, rats of each group were fed diets with or without WSSF (50 g/kg diet) for 4 wk. RESULTS: Net calcium absorption and femoral dry weight and calcium content and maximum breaking force were lower in the gastrectomy groups than in the sham groups. In the gastrectomy groups, calcium absorption and these femoral parameters were higher in rats fed the WSSF diet than in rats fed the WSSF-free diet. Feeding WSSF increased the concentrations of short-chain fatty acids and soluble calcium and decreased the pH in cecal contents. Net calcium absorption in gastrectomized rats correlated positively with the concentration of total short-chain fatty acids (the sum of acetic, propionic, and butyric acids) in cecal contents (r = 0.545, P < 0.05) and negatively with cecal pH (r = -0.628, P < 0.05). CONCLUSIONS: These findings indicate that ingestion of WSSF partly prevents the diminished calcium absorption after total gastrectomy in rats, resulting in the improvement of postgastrectomy osteopenia. The increase of calcium absorption may be associated with cecal fermentation of WSSF.

Acetic Acid↗