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Biomedical subjects

S Ikegami

Publications and source records attributed to S Ikegami.

At least 55 records · Page 3Linked to original sources
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

Vitamin A and carotenoids stimulate differentiation of mouse osteoblastic cells.

The action of retinol and carotenoids on bone cells was investigation in vitro by evaluating cell growth, alkaline phosphatase activity and the mRNA expression of a differentiation marker protein of osteoblastic cells. The clonal osteogenic cell line MC3T3-E1, established from newborn mouse calvaria, has a capacity of differentiation into osteoblast and mineralization in vitro. Retinol and beta-carotene inhibited the proliferation of MC3T3-E1 cells as well as DNA synthesis of the cells in a dose-dependent manner. Retinol induced differentiation of the MC3T3-E1 cells, by increasing alkaline phosphatase activity dose dependently, in a range from 1 to 100nm. Beta-carotene increased alkaline phosphatase activity is a dose-related manner in a range from 0.1 to 5 microM. Osteopontin is one of the matrix proteins which osteoblasts produce. Retinol increased the expression of osteopontin mRNA in a range from 1 to 100 nm. Beta-carotene also increased osteopontin mRNA expression, reaching a plateau at 1 microM. The induction of differentiation of MC3T3-E11 cells by beta-carotene was dose-dependent but was two orders of magnitude less active than that produced by retinoids. Within the MC3T3-E1 cells, part of the beta-carotene was effectively converted into retinol. Alpha-carotene, canthaxanthin and lycopene also inhibited cell proliferation at 1 microM and increased alkaline phosphatase activity and osteopontin mRNA expression, but less potently so than beta-carotene. Retinol and carotenoids were concluded to have a direct stimulatory effect on the differentiation of osteoblasts at the physiological concentration.

3T3 Cells↗
PubMed1996

A facilitatory effect on the induction of long-term potentiation in vivo by chronic administration of antisense oligodeoxynucleotides against catalytic subunits of calcineurin.

A rise in Ca2+ concentration at postsynaptic sites provides an initial step in inducing both the long-term potentiation (LTP) and long-term depression (LTD) in the CA1 region of the hippocampus. LTP induction requires the activation of Ca(2+)-sensitive protein kinases following the rise in Ca2+. By contrast, the activity of protein phosphatase(s) appears to be critical to induce LTD. Here we demonstrate that inhibition of the synthesis of calcineurin A alpha and A beta, catalytic subunits of Ca2+/calmodulin- (CaM) dependent protein phosphatase, reduces the threshold of induction for commissural-CA1 LTP in anesthetized rats. In rats administered antisense oligodeoxynucleotides (ODNs) against calcineurin A alpha and A beta intraventricularly for 7 days, a brief tetanic stimulation to the CA3 region, which in the control case was below threshold for the induction of LTP, now produced a long-lasting increase in both the EPSP slope and the amplitude of population spike recorded from the commissural-CA1 pathway. Western blot analysis of calcineurin showed that the threshold reduction was accompanied by a selective decrease in the protein levels in the hippocampus. Thus our study provides direct evidence that calcineurin per se has an antagonizing role in LTP induction. Complementary experiments with the selective calcineurin inhibitor, FK506, also showed the reduction of LTP threshold in a dose-dependent manner. These results, together with previous studies, support the hypothesis that the quantitative phosphorylation level of critical intracellular proteins determines whether the synaptic efficacy will increase or decrease after the activity-dependent rise in postsynaptic Ca2+.

Animals↗
PubMed1996

Effect of boiled barley-rice-feeding in hypercholesterolemic and normolipemic subjects.

Barley contains approximately 10% dietary fiber and is easily cooked with rice, the dominant cereal in Japan, to increase the intake of dietary fiber. This research involved three experiments to examine the influence of barley on blood lipids in human subjects. All subjects received a boiled barley-rice (50/50 w/w mix) supplement two times per day in place of rice for 2 or 4 weeks. In the normolipemic subjects, serum lipids were unaffected by the ingestion of barley for 4 weeks. In twenty hypercholesterolemic men aged 41 +/- 5 years, the ingestion of barley was associated with a significant fall in serum total cholesterol, LDL-cholesterol, phospholipids and LDL and VLDL-lipoproteins. In seven mildly hypercholesterolemic women aged 56 +/- 7 years, a significant improvement of serum lipid profiles was observed. The present study suggests the possibility that the ingestion of barley-rice could lower serum lipids in hypercholesterolemic subjects.

Adult↗
PubMed1996

Purification and characterization of thermostable maltooligosyl trehalose synthase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius.

A thermostable maltooligosyl trehalose synthase was purified from a cell-free extract of the thermoacidophilic archaebacterium Sulfolobus acidocaldarius ATCC 33909 to an electrophoretically homogeneous state by successive column chromatography on Sepabeads FP-DA13, Butyl-Toyopearl 650M, DEAE-Toyopearl 650S, Ultrogel AcA44, and Mono Q. The enzyme had a molecular mass of 74,000 by SDS-polyacrylamide gel electrophoresis and a pI of 5.9 by gel isoelectrofocusing. The N-terminal amino acid of the enzyme was methionine. The enzyme showed the highest activity from pH 5.0 to 5.5 and at 75 degrees C, and was stable from pH 4.5 to 9.5 and up to 85 degrees C. The enzyme activity was inhibited by Hg2+ and Cu2+. The Kms of the enzyme for maltotetraose, maltopentaose, maltohexaose, maltoheptaose, and short chain amylose (DP 18) were 41.5 mM, 7.1 mM, 5.7 mM, 1.4 mM, and 0.6 mM, respectively.

Amino Acid Sequence↗
PubMed1996

Purification and characterization of thermostable maltooligosyl trehalose trehalohydrolase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius.

A thermostable maltooligosyl trehalose trehalohydrolase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius ATCC 33909 was purified from a cell-free extract to an electrophoretically pure state by successive column chromatographies on Sepabeads FP-DA13, Butyl-Toyopearl 650M, DEAE-Toyopearl 650S, Toyopearl HW-55S and Ultrogel AcA44. The enzyme had a molecular mass of 59,000 by SDS-polyacrylamide gel electrophoresis and a pI of 6.1 by gel isoelectrofocusing. The N-terminal amino acid of the enzyme was methionine. The enzyme showed the highest activity from pH 5.5 to 6.0 and at 75 degrees C, and was stable from pH 5.5 to 9.5 and up to 85 degrees C. The activity was inhibited by Hg2+, Cu2+, Fe2+, Pb2+, and Zn2+. The Km values of the enzyme for maltosyl trehalose, maltotriosyl trehalose, maltotetraosyl trehalose, and maltopentaosyl trehalose were 16.7 mM, 2.7 mM, 3.7 mM, and 4.9 mM, respectively.

Chemical Phenomena↗
PubMed1996

An assessment of docosahexaenoic acid (DHA) intake with special reference to lipid metabolism in rats.

In order to determine the appropriate intake of docosahexaenoic acid (22:6n-3, DHA), the potential changes in lipid peroxidation and antioxidant defense in serum and tissue as well as the changes in serum lipid levels were examined in rats by giving them diets containing graded levels of purified DHA (0, 1.0, 3.4 and 8.7 energy % in the diets) for 2 weeks. Serum alpha-tocopherol concentration decreased slightly but significantly even at the 1.0 energy %. Liver lipid peroxide levels as assessed by the thiobarbituric acid (TBA) value and chemiluminescence intensity augmented at the 3.4 energy % and more, and the alpha-tocopherol content significantly decreased in response to the increase in lipid peroxide levels. In the kidney, a slight but significant increase in TBA value was observed even at 1.0 energy % and higher. All the serum lipid levels as analyzed by total cholesterol, HDL-cholesterol, triacylglycerol (TG) and phospholipids (PLs) decreased as the dietary DHA level increased. These experimental results suggest that the dietary intake of DHA should be less than 1 energy % to avoid promoting deleterious influences such as serum and tissue lipid peroxidation and to ameliorate serum lipid levels.

Animals↗
PubMed1996

Changes in activity, antigenicity, and molecular size of rice bran trypsin inhibitor by in vitro digestion.

Rice bran trypsin inhibitor (RBTI) was digested by pepsin alone or by pepsin and pancreatin with or without bovine serum albumin (BSA) to clarify the changes in trypsin inhibitory activity, apparent antigenicity, and molecular size of RBTI. In vitro pepsin digestion of RBTI in the absence of BSA caused the gradual loss of the trypsin inhibitory activity and antigenicity. This was mostly due to a progressive degradation of the native 14.5-kDa RBTI molecule to small molecular mass products. The presence of BSA in the digestion mixture prevented the RBTI degradation and was accompanied with a considerable protection of the activity and antigenicity. Similar results were also given by in vitro pepsin-pancreatin digestion. These findings suggest that RBTI may be present in its active form in the gastrointestinal tract when fed to animals, especially with a dietary protein.

Chromatography, High Pressure Liquid↗
PubMed1996

The origin of SL family mice.

The origin of SL family mice was studied by analyzing 100 microsatellite loci, the major histocompatibility complex, the Mx gene, murine leukemia provirus, and mammary tumor provirus. From the genetic profile of family members and their history, we assumed the existence of a proto-SL mouse, an ancestor of all SL family members. Many alleles were contributed to the proto-SL by the ancestors related to strains A2G and CF#1, and/or some wild mice. Among four existing family members, SL/Am and SL/Ni mice were almost identical and presumably closest to the proto-SL. The SL/Kh mouse was derived from a cross of the proto-SL and AKR mice, because SL/Kh mice inherited a considerable number of genes from AKR mice, the most outstanding of which were those of the provirus Emv-11 and Thy-1.1. The SL/QDj mice seemed to be a recombinant inbred strain between SL/Am and SL/Kh mice, because their alleles at all 100 microsatellite loci were shared by SL/Am or SL/Kh strains or both. All four SL family members shared the major histocompatibility complex haplotype q.

Animals↗
PubMed1995

Selective inhibition of gastrulation in the starfish embryo by albuside B, an inosine analogue.

External application of 0.2-100 micrograms/ml albuside B inhibits gastrulation of the starfish (Asterina pectinifera) embryo. Treated embryos retain the late blastula morphology with the vegetal plate. However, the vegetal plate is unreactive to soybean agglutinin, a probe for observing the progenitor cells of the archenteron (mesendoderm) in a normal embryo. The effective period of the treatment is limited from 4 to 6 h after fertilization, a period immediately before the onset of blastulation. RNA synthesis is unaffected during the period of sensitivity. The selectivity of the inhibition shows that albuside B may be a useful tool for studying the mechanisms of mesendoderm differentiation.

Animals↗
PubMed1995

1-Acetyl-7-deacetylforskolin: a potential non-specific inactive analog of forskolin for estimation of its specific high-affinity binding and adenylyl cyclase stimulation in vitro.

Labeled and unlabeled 1-acetyl-7-deacetylforskolin and forskolin were synthesized by acetylation of 7-deacetylforskolin with labeled and unlabeled acetyl chloride. The binding of 1-acetyl[1-acetyl-11C]-7-deacetylforskolin ([11C]1-acetyl-7-deacetylforskolin) and [7-acetyl-11C]forskolin ([11C]forskolin) to rat brain membranes was studied using filtration assay. The [11C]forskolin binding was decreased with an increasing load of unlabeled forskolin, whereas [11C]1-acetyl-7-deacetyl-forskolin binding was always very low, the level of which agreed with that of the non-specific binding in forskolin. However, binding of [7-acetyl-11C]1,9-dideoxyforskolin, which has been used as a non-specific inactive analog of forskolin, had a higher binding ratio than that of the non-specific binding of forskolin. The binding of [11C]forskolin was not affected by an increased load of cold 1-acetyl-7-deacetylforskolin. Forskolin activated adenylyl cyclase (AC) in cultured human endothelial cells, whereas 1-acetyl-7-deacetylforskolin did not. These data show that the 1-acetyl-7-deacetylforskolin lacks specific binding affinity and the ability to stimulate AC, while it has similar physical properties with forskolin. The compound 1-acetyl-7-deacetylforskolin would be a suitable "non-specific inactive analog" of forskolin with which to estimate its specific high-affinity binding capacity and to validate forskolin-specific AC stimulation in vitro.

Adenylyl Cyclases↗
PubMed1995

Fish oil enhances pentachlorobenzene metabolism and reduces its accumulation in rats.

To investigate the influence of dietary fats on the metabolism and excretion of pentachlorobenzene (PECB), rats were fed semipurified diets containing soybean oil, lard or fish oil (10 g/100 g diet) for 2 wk. Rats then received a single dose of PECB by intragastric gavage. Blood concentration of pentachlorophenol (PCP), a major metabolite of PECB, was higher after 5 h through d 3 and that of PECB was lower after d 5 in the rats fed fish oil than in rats fed the other fats. After d 5, the highest ratio of PCP/PECB in the liver was seen in the fish oil-fed rats. Furthermore, fish oil intake resulted in a markedly lower concentration of PECB in fat tissues, where a large amount of PECB is typically distributed due to its lipophilic property. These findings indicate that fish oil feeding enhances PECB metabolism, thereby decreasing PECB residues in the body. Fish oil-fed rats had a smaller epididymal fat tissue mass compared with lard- or soybean oil-fed rats. The small mass of the fat tissues apparently limited the accumulation of PECB in those tissues and thus accelerated PECB metabolism in the liver.

Adipose Tissue↗
PubMed1995

Urachal adenocarcinoma accompanied by a large spherical calcified mass.

We report a case of urachal adenocarcinoma, accompanied by a large spherical calcified mass adherent to the bladder dome of a 63-year-old man. The patient underwent partial cystectomy including en bloc resection of the urachus, and remains free from the disease after a 32-month follow-up period.

Adenocarcinoma↗
PubMed1994

Behavioral impairment in radial-arm maze learning and acetylcholine content of the hippocampus and cerebral cortex in aged mice.

Age-related changes in spatial learning performance were studied in relation to acetylcholine (ACh) content of brain regions in male aged (28-month-old) and young (5-month-old) mice of BDF1 strain. As there were large individual differences in the spatial performance of aged mice, the aged mice were divided into two subgroups, old A and old B. The old A group included the six best performers out of the 12 aged mice and the old B group included the remaining 6 worst performers. In a radial-arm maze task with 8 baited arms, aged mice in the old B group showed a marked deficit in acquisition performance and habituation to the apparatus. In the more difficult maze task with only 4 baited arms, the aged mice in the old B group exhibited marked impairment both in working memory and reference memory throughout training, whereas the aged mice in the old A group showed deficits in reference memory during the first 20 days of training and working memory during the last 20 days relative to young mice. Neurochemical analysis revealed significant decreases in the ACh content of the hippocampus and striatum in both aged groups, and in the frontal cortex and posterior cortex of the old B group as compared to the young group. Correlational analysis showed significant correlations between learning performance in the spatial task and ACh levels in the hippocampus, frontal cortex, and posterior cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Selective inhibition of exoplasmic membrane fusion in echinoderm gametes with jaspisin, a novel antihatching substance isolated from a marine sponge.

A specific inhibitor of fertilization of the sea urchin Hemicentrotus pulcherrimus was isolated from the extract of the marine sponge, Jaspis species. Chemical and spectral data of the purified substance, which was designated jaspisin, showed that it is a novel substance with the structure of sodium (E)-5,6-dihydroxystyryl sulfate. Jaspisin at 15 micrograms/ml inhibited exoplasmic fusion of the plasma membrane of acrosome-reacted sperm with the plasma membrane of the egg; it did not affect either the acrosome reaction in sperm or the egg cortical reaction, both of which involve endoplasmic membrane fusion events. When a fertilized egg was cultured in jaspisin, the embryo developed through the mesenchymal blastula stage. However, it was unable to hatch from the fertilization envelope, and spiculogenesis, in which cell-cell fusion of primary mesenchyme cells is involved, was prevented. Jaspisin at 8.6 micrograms/ml inhibited half the activity of hatching enzyme, a kind of Zn(2+)-dependent metalloendoproteinases. Because Zn(2+)-activated metalloendoproteinases are suggested to be involved in both sperm-egg fusion and fusion of primary mesenchyme cells (Lennarz, W.J., and Strittmatter, W.J. (1991) Biochim. Biophys. Acta 1071, 149-158), one of the possible explanations of the jaspisin effects is that the sulfate inhibits these cellular events through blockage of Zn(2+)-activated metalloendoproteinases that are involved in membrane fusion processes.

Animals↗
PubMed1994

Differential inhibition of eukaryotic DNA polymerases by halenaquinol sulfate, a p-hydroquinone sulfate obtained from a marine sponge.

Halenaquinol sulfate, a p-hydroquinone sulfate obtained from a marine sponge, inhibited the activity of eukaryotic DNA polymerases in varying degrees; the Ki values for DNA polymerases, alpha, beta, delta and epsilon were 1.3, 80, 17.5 and 2.0 microM, respectively, whereas it was less effective against E. coli DNA polymerase I. The inhibition occurred competitively with each of dATP and dTTP, but non-competitively with dCTP, dGTP and the template DNA. Thus, halenaquinol sulfate is demonstrated to be a potential inhibitor of DNA polymerases alpha and epsilon, and be a useful tool for analyzing the dNTP binding sites of DNA polymerases.

Animals↗
PubMed1994

Effect of beta-carotene on spontaneous and X-ray-induced chromosomal damage in bone marrow cells of mice.

The effect of beta-carotene on spontaneous and X-ray-induced chromosomal damage in bone marrow cells of mice was studied. As a source of beta-carotene, dried Dunaliella bardawil (containing 6% beta-carotene) or oil suspension of Dunaliella beta-carotene was used. In Experiment 1, mice were given a basal diet, a 0.5% Dunaliella diet, or a 4% Dunaliella diet for four weeks. In Experiment 2, mice were given an oil suspension of Dunaliella beta-carotene (300 mg/kg body wt) by gavage for seven days while being fed a fat-rich diet. After beta-carotene treatment for the indicated time, spontaneous and X-ray (0.3 Gy, whole-body)-induced chromosomal damage in bone marrow cells was evaluated in terms of the percentages of micronucleated reticulocytes in their peripheral blood. The beta-carotene treatment slightly lowered the spontaneous and X-ray-induced chromosomal damage in bone marrow cells. Despite the higher doses of beta-carotene, the concentrations of beta-carotene in bone marrow, liver, and serum were much lower than those of vitamin E. In addition, the beta-carotene treatment markedly lowered the concentration of vitamin E in the tissues.

Animals↗