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Biomedical subjects

S Shimamura

Publications and source records attributed to S Shimamura.

At least 55 records · Page 3Linked to original sources
PubMed1995

Effect of administration of bifidobacteria and lactic acid bacteria to newborn calves and piglets.

The effect of oral administration of bifidobacteria and lactic acid bacteria on newborn livestock was investigated. Oral administration of Bifidobacterium pseudolongum or Lactobacillus acidophilus to calves improved BW gain and feed conversion over that of untreated controls. The frequency of diarrhea occurrence was decreased in the group fed probiotics. However, there was no significant difference between calves administered B. pseudolongum and those administered L. acidophilus. Under conditions of feeding without antibiotics, the frequency of diarrhea was decreased markedly by administration of probiotics. The BW gain of piglets was significantly greater during both the suckling and weaning periods for the group fed probiotics than for the control group. The effect was more evident during the suckling period than during the weaning period. Under conditions of feeding without antibiotics, the frequency of piglet mortality was decreased markedly by administration of probiotics. The probiotics tested here had useful effects, including improved BW gain, feed conversion, and fecal condition of both newborn calves and piglets.

Animal Feed↗
PubMed1994

Lactoferrin inhibits cholesterol accumulation in macrophages mediated by acetylated or oxidized low-density lipoproteins.

When macrophages are incubated with acetylated or oxidized low-density lipoproteins (Ac- or OxLDL), cellular cholesteryl esters (CE) increase significantly. In the present study, we investigated the effect of whey protein on Ac- or OxLDL mediated accumulation of CE in macrophages and found that lactoferrin (Lf), a minor protein component of whey, inhibits the accumulation of CE dose-dependently. In the presence of bovine Lf (1 mg/ml), CE accumulation in macrophages incubated with AcLDL (100 micrograms of protein/ml) decreased by more than 80%. Human Lf was less potent than bovine Lf, and bovine transferrin had no effect. Binding of 125I-AcLDL to macrophages was also inhibited by Lf. Agarose gel electrophoresis revealed that Lf binds to Ac- or OxLDLs and neutralizes their negative charges. These results indicate that Lf inhibits the binding of modified LDLs to macrophages by direct interaction with modified LDLs, resulting in their loss of function as ligands of the scavenger receptor. Modification of the arginine residues of Lf with 1,2-cyclohexanedione abolished its ability to bind to AcLDL, suggesting that a region rich in basic amino acid residues near the N-terminus of Lf, which resembles the ligand-binding site of the scavenger receptor, may be responsible for this binding ability. As a result, the inhibitory effect of Lf on CE accumulation in macrophages was significantly weakened by this modification. Our results suggest the possibility that Lf in the blood stream may act as an anti-atherogenic agent in vivo.

Amino Acid Sequence↗
PubMed1994

Physicochemical and antibacterial properties of lactoferrin and its hydrolysate produced by heat treatment at acidic pH.

In order to apply functionally active lactoferrin (Lf) to food products, the effect of pH on the heat stability of Lf was studied. Lf was easily denatured to an insoluble state by heat treatment under neutral or alkaline conditions, above pH 6. In contrast, it remained soluble after heat treatment under acidic conditions at pH 2 to 5, and the HPLC pattern of Lf heat-treated at pH 4 at 100 degrees C for 5 min was the same as that of native Lf. Lf was found to be very thermostable at pH 4, and could be pasteurized or sterilized without any significant loss of its physicochemical properties. Lf was hydrolyzed by heat treatment at pH 2 to 3 at above 100 degrees C, and its iron binding capacity and antigenicity were lost. But the antibacterial activity of the hydrolysate was found to be much stronger than that of native Lf. The antibacterial component of Lf hydrolysate produced by heat treatment at acidic pH was verified to be a peptide including the sequence of residues 1-54 from the N-terminal end of the bovine Lf molecule.

Amino Acid Sequence↗
PubMed1994

Lactoferrin promotes nerve growth factor synthesis/secretion in mouse fibroblast L-M cells.

Fibroblast cells are known to have an ability to synthesize and secrete nerve growth factor (NGF). To investigate the mechanism of action of the iron-binding protein, lactoferrin (Lf), on cultured animal cells, the effect of bovine Lf (bLf) on NGF synthesis/secretion in mouse fibroblast cells was examined. Both apo- and holo-bLf induced an increase in NGF content in the cell-conditioned medium(CM) of mouse L-M cells, a line derived from L929 fibroblast cells, with similar effectiveness. The increase in NGF content in the CM of L-M cells cultured with bLf was not dependent on the induction of increase in cell numbers, but was due to induction of de novo synthesis of NGF in individual cells by bLf. Human Lf(hLf) also increased NGF content. However, apo- and holo-bovine transferrin (bTf) failed to stimulate the NGF synthesis. The time-dependent induction of NGF in L-M cells by bLf was different from that induced by basic fibroblast growth factor (bFGF) and bLf showed an additive effect with bFGF. These results suggest that the induction of NGF synthesis depends on a mechanism different from iron transport or bFGF.

Animals↗
PubMed1994

A review: the active peptide of lactoferrin.

A potent antimicrobial peptide, 'lactoferricin', was found to be generated upon gastric pepsin cleavage of lactoferrin. The active peptide consists mainly of a loop of 18 amino acid residues, derived from the N-terminal region of the lactoferrin molecule. Like various other antimicrobial peptides that display membrane-disruptive properties, it contains a high proportion of basic amino acid residues. A physiologically diverse range of micro-organisms was tested and found to be susceptible to inhibition by this natural peptide including Gram-negative and Gram-positive bacteria, yeasts and filamentous fungi. Its antimicrobial effect against sensitive micro-organisms was lethal. Electron microscopy studies revealed that it induces a profound change in cell ultrastructural features and causes substantial cell damage in bacteria and fungi. These findings suggest the possibility that active peptides of lactoferrin may have a role in the host defense against microbial disease. If produced in substantial quantities in vivo such peptides could have important physiological significance, especially in nursing infants.

Amino Acid Sequence↗
PubMed1993

Killing of Candida albicans by lactoferricin B, a potent antimicrobial peptide derived from the N-terminal region of bovine lactoferrin.

Candida albicans was found to be highly susceptible to inhibition and inactivation by lactoferricin B, a peptide produced by enzymatic cleavage of bovine lactoferrin. Effective concentrations of the peptide varied within the range of 18 to 150 micrograms/ml depending on the strain and the culture medium used. Its effect was lethal, causing a rapid loss of colony-forming capability. 14C-labeled lactoferricin B bound to C. albicans and the rate of binding appeared to be consistent with the rate of killing induced by the peptide. The extent of binding was diminished in the presence of Mg2+ or Ca2+ ions which acted to reduce its anticandidal effectiveness. Binding occurred optimally at pH 6.0 and killing was maximal near the same pH. Such evidence suggests the lethal effect of lactoferricin B results from its direct interaction with the cell surface. Cells exposed to lactoferricin B exhibited profound ultrastructural damage which appeared to reflect its induction of an autolytic response. These findings suggest that active peptides of lactoferrin could potentially contribute to the host defense against C. albicans.

Amino Acid Sequence↗
PubMed1993

Analysis of human and bovine milk lactoferrins by Rotofor and chromatofocusing.

1. Isoelectric points of human and bovine lactoferrins were evaluated by Rotofor and chromatofocusing analysis. 2. By Rotofor, the isoelectric value of human lactoferrin fraction was determined at 8.7 and that of bovine lactoferrin at 8.8. 3. By chromatofocusing analysis, human and bovine lactoferrins showed different elution patterns. Human lactoferrin was eluted at pH 6.8-8 and bovine lactoferrin eluted at pH 8.2-8.9.

Animals↗
PubMed1993

Genetic and molecular analysis of the rpoD gene from Lactococcus lactis.

A gene of Lactococcus lactis ATCC19435, the product of which is homologous with the principal sigma factors of Escherichia coli and Bacillus subtilis, was cloned and sequenced. The deduced amino acid sequence of the 340-residue protein and the upstream open reading frame of the cloned gene showed a homology to B. subtilis sigma 43 factor (the rpoD product) and DNA primase (the dnaE product), respectively, suggesting that L. lactis also has the rpoD operon. Surprisingly, introduction of the cloned L. lactis rpoD gene into a rpoD temperature-sensitive mutant of E. coli caused partial complementation.

Amino Acid Sequence↗
PubMed1993

Stimulation by bovine lactoferrin of nerve growth factor synthesis/secretion in mouse L-M cells.

Cultured mouse fibroblasts synthesize and secrete nerve growth factor (NGF). To learn the mechanism of action of an iron-binding protein, lactoferrin (Lf), on cultured animal cells, we have examined the effects of bovine Lf (bLf) on NGF synthesis/secretion in mouse L-M cells, a line derived from L929 fibroblast cells. Both apo- and holo-bLf induced an increase in NGF content in the cell-conditioned medium (CM) with similar effectiveness. Neither apo- nor holo- bovine transferrin (bTf) was effective, indicating that the observed induction of NGF production cannot be attributed to stimulation of iron transport. A basic peptide fragment of bLf (residues 17-41) isolated from a pepsin hydrolyzate of bLf was found to be effective for stimulation of NGF synthesis/secretion in L-M cells. This observation demonstrates that the basic nature of Lf is important for its interaction with fibroblast cells.

Amino Acid Sequence↗
PubMed1993

Iron-binding properties of bovine lactoferrin in iron-rich solution.

The iron-binding properties of bovine lactoferrin in iron-rich solution were investigated. Ferrous iron was not stable in solution and was easily changed to the insoluble ferric state, but solubility of ferrous iron was stabilized by the presence of lactoferrin. However, casein hydrolysate or BSA was not effective in stabilizing iron in solution. As indicated by use of cibacron blue affinity gel, iron bound to lactoferrin, and the charge of supersaturated lactoferrin was higher than that of normal iron-saturated lactoferrin according to native PAGE electrophoresis. The evidence suggests that lactoferrin can bind iron at sites other than its chelate-binding sites, thereby stabilizing iron in solution.

Animals↗
PubMed1993

Role of cell-binding in the antibacterial mechanism of lactoferricin B.

The antibacterial cell-binding properties of lactoferricin B, a potent bactericidal peptide derived from bovine lactoferrin, were investigated for the first time. To facilitate measurements of binding the peptide was radiolabelled by reduction and treatment with iodo-[1-14C]acetamide. 14C-lactoferricin B bound rapidly to the surface of Escherichia coli and Bacillus subtilis. The rate of binding was consistent with the rapid rate of killing caused by this peptide. The extent of binding was reduced in the presence of Mg2+ or Ca2+ ions which act to reduce its antimicrobial effectiveness. The optimal pH for binding was strain-dependent and the killing effect was maximal near the optimal pH for cell binding with each strain tested. These observations indicate that direct interaction of lactoferricin B with the cell surface is necessary for its lethal effect. The number of peptide molecules bound (> 10(6) per cell) was more than would be expected for binding to specific protein receptors. Lactoferricin B inhibited bacterial uptake of 3H-proline with effectiveness similar to polymyxin B, a known membrane-disruptive agent. The cell-binding event appears to lead to a disruption of normal permeability functions of the cytoplasmic membrane.

Anti-Bacterial Agents↗
PubMed1992

Relationship between oxygen sensitivity and oxygen metabolism of Bifidobacterium species.

Bifidobacteria, which are obligate anaerobes, were studied to determine the relationship between their sensitivity to oxygen and oxygen metabolism. Among the four species tested, Bifidobacterium infantis, Bifidobacterium breve, and Bifidobacterium longum differed from Bifidobacterium adolescentis in sensitivity to oxygen. The former three species showed marked growth under conditions of partial aeration, whereas the growth of B. adolescentis was suppressed by low concentrations of oxygen. Bifidobacteria express reduced NAD-oxidase and -peroxidase activities, which function in a pathway for two-electron reduction of molecular oxygen, producing hydrogen peroxide and, subsequently, water. Activities of reduced NAD-oxidase and -peroxidase were inversely correlated with their sensitivities to oxygen. Bifidobacterium adolescentis exhibited lowered activities of these two enzymes; the activities were 10 to 20% of those observed with B. infantis, B. breve, and B. longum. These observations are compatible with the hypothesis that reduced NAD-oxidase and reduced NAD-peroxidase in Bifidobacterium species play a role in prevention of oxygen toxicity. Superoxide dismutase activity was also detected in Bifidobacterium species. Superoxide dismutase is probably not involved in detoxification of oxygen, because the activity of this enzyme was extremely low, and the sensitivity to oxygen varied independently of superoxide dismutase activity.

Bifidobacterium↗
PubMed1991

Potent bactericidal activity of bovine lactoferrin hydrolysate produced by heat treatment at acidic pH.

A hydrolysate of bovine lactoferrin produced by heat treatment under acidic conditions had antibacterial activity at concentrations of 10 micrograms/ml in the culture medium. The optimal degree of hydrolysis for this activity was about 10%. Heat-treated lactoferrin, treated at pH 2.0 and 120 degrees C for 15 min and degree of hydrolysis of about 10%, had no Fe-binding capacity (0%) and less antigenicity (about 10(-6) than untreated lactoferrin. Heat-treated lactoferrin increased in antibacterial activity, and the activity was maintained in an Fe-rich medium. After fractionation of heat-treated lactoferrin by reverse-phase HPLC, several peptide fractions were found that had strong antibacterial activity. It was suggested that lactoferrin latently contains at least one bactericidal domain that is activated upon release by limited acid hydrolysis of the protein. The bactericidal activity of the peptide fragments of lactoferrin was shown to have no relation to Fe chelation, in contrast with the antibacterial mechanism of native lactoferrin.

Animals↗
PubMed1990

Modulation by polyamines of DNA-dependent DNA polymerase activity from human serum.

1. Spermine, spermidine and putrescine activated DNA-dependent DNA polymerase from human sera by 47-125% at the concentrations of 0.2, 3 and 30 mM, respectively. 2. The polyamines shifted the optimal MgCl2 concentration for the polymerase activity from 10 mM to more physiological 5 mM. 3. Histamine having amino and imino groups at both ends of the molecule also increased the DNA polymerase activity, while cyclopentylamine and n-butylamine showed no effects on the enzyme activity. 4. The stimulatory effect of polyamines on the DNA polymerase activity was more evident with poly(dC)p(dG) used as a template/primer than with poly(dA)p(dT).

DNA↗
PubMed1988

[Risk factors of undescended testis].

A study on possible association of maternal factors with undescended testis was undertaken. A comparison was made using mothers of boys with the disease (No. = 108) and mothers of boys without the disease (No. = 108). The boys without the disease were selected from outpatients by individually matching the birth year with the case. A smaller proportion of mothers having babies with the disease experienced vomiting during the index pregnancy (the estimated relative risk RR = 0.51, P = 0.02). A larger proportion of them had delivered by vacuum extractor delivery, cesarean section, or breech extraction (RR = 2.10, P = 0.04). A higher proportion of cases were complicated with inguinal hernia (RR = 9.00, P = 0.03), congenital cardiac diseases (RR = infinity, P = 0.008), or other various kinds of congenital disorders. A larger proportion of these mothers had never breastfed for the cases (RR = 3.75, P = 0.02). Exposure to external estrogen in the utero was not noted to be associated with undescended testis.

Analysis of Variance↗