Biomedical subjects

Y Sakagami

Publications and source records attributed to Y Sakagami.

At least 55 records · Page 3Linked to original sources

PubMed1998

Differential induction by methyl jasmonate of genes encoding ornithine decarboxylase and other enzymes involved in nicotine biosynthesis in tobacco cell cultures.

A cDNA of tobacco BY-2 cells corresponding to an mRNA species which was rapidly induced by methyl jasmonate (MeJA) in the presence of cycloheximide (CHX) was found to encode ornithine decarboxylase (ODC). Another cDNA from a MeJA-inducible mRNA encoded S-adenosylmethionine synthase (SAMS). Although these enzymes could be involved in the biosynthesis of polyamines, the level of putrescine, a reaction product of ODC, increased slowly and while the levels of spermidine and spermine did not change following treatment of cells with MeJA. However, N-methylputrescine, which is a precursor of pyrrolidine ring of nicotine, started to increase shortly after MeJA-treatment of cells and the production of nicotine occured thereafter. The levels of mRNA for arginine decarboxylase (ADC), an alternative enzyme for putrescine synthesis, and that for S-adenosylmethionine decarboxylase (SAMDC), required for polyamine synthesis, were not affected by MeJA. In addition to mRNAs for ODC and SAMS, mRNA for putrescine N-methyltransferase (PMT) was also induced by MeJA. Unlike the MeJA-induction of ODC mRNA, MeJA-induction of SAMS and PMT mRNAs were blocked by CHX. The level of ODC mRNA declined after 1 to 4 h following MeJA treatment, while the levels of mRNAs for SAMS and PMT continued to increase. Auxin significantly reduced the MeJA-inducible accumulation of mRNAs for ODC, SAMS and PMT. These results indicate that MeJA sequentially induces expression of a series of genes involved in nicotine biosynthesis by multiple regulatory mechanisms.

Acetates↗

PubMed1998

Anti-MRSA activity of sophoraflavanone G and synergism with other antibacterial agents.

Anti-MRSA activity of sophoraflavanone G (SFG) and synergism between SFG and antibacterial agents against MRSA (methicillin-resistant Staphylococcus aureus) were evaluated by means of Minimal Inhibitory Concentrations (MIC). The MICs of SFG against 27 strains of MRSA ranged from 3.13 to 6.25 micrograms ml-1. Synergism between SFG and vancomycin hydrochloride (VCM) or fosfomycin (FOM) was observed (the fraction inhibitory concentration (FIC) indices were 0.16 and 0.48), while partial synergism was admitted between SFG and other antibacterial agents such as methicillin (DMPPC), cefzonam (CZON), gentamicin (GM), minocycline (MINO) and levofloxacin (LVFX) (the FIC indices were 0.71, 0.73, 0.69, 0.65 and 0.58, respectively). These findings suggest that SFG in combination with VCM or FOM may be useful in controlling MRSA infections.

Anti-Bacterial Agents↗

PubMed1998

Insecticidal and antifungal activities of aminorhodanine derivatives.

Aminorhodanine (1) showed strong insecticidal activity against Culex pipiens pallens and Musca domestica, with respective LD50 values of 0.21 microgram/insect and 0.87 microgram/insect. Compound 1 had antifungal activity against Aspergillus niger ATCC-16404, Trichophyton mentagrophytes IFO-32412, Candida albicans ATCC-10231, Hansenula anomala OPS-308 and Penicillium expansum IFO-8800. In particular, 1 had potent antifungal activity against Aspergillus niger ATCC-16404, its minimal inhibitory concentration (MIC) being 6.25 micrograms/ml. Both activities of 1 were much higher than those of rhodanine (4), suggesting that the introduction of an amino group into N-3 of 4 plays an important role in the biological activity of rhodanine-related compounds. On the other hand, N-acetylaminorhodanine (2) and N-benzoylaminorhodanine (3) did not show either activity, suggesting that the free amino group at N-3 of 1 is closely related to the inhibitory activity of rhodanine derivatives.

Animals↗

PubMed1998

Cystothiazoles A and B, new bithiazole-type antibiotics from the myxobacterium Cystobacter fuscus.

New bithiazole-type antibiotics, cystothiazoles A (C20H26N2O4S2) and B (C20H26N2O5S2), have been isolated from a culture broth of the myxobacterium, Cystobacter fuscus. The gross structures of these compounds were elucidated by spectroscopic analysis, and their absolute stereochemistry was determined by chemical degradation of cystothiazole A. Cystothiazole A inhibits fungi and human tumor cells, whereas it is inactive against bacteria. The antifungal activity appears to result from the inhibition of submitochondrial NADH oxidation. Although these compounds are structurally related to the known antibiotic myxothiazol, cystothiazole A was more active against fungi and less cytotoxic than myxothiazol.

Anti-Bacterial Agents↗

PubMed1998

Toxicity of hydrogen peroxide produced by electroplated coatings to pathogenic bacteria.

The ability of various electroplated coatings (cobalt, zinc, copper, and cobalt-containing alloys of nickel, zinc, chromium, etc.) to inhibit the growth of pathogenic bacteria (Gram-positive bacteria Enterococcus faecalis and methicillin-resistant Staphylococcus aureus and Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) was determined by a drop-method antibacterial experiment. The amounts of H2O2 produced and metal ions dissolved from the surfaces of various electroplated coatings were measured and it was found that the inhibitory ability of coatings corresponded to the amounts of H2O2 produced. The more significant the inhibition of the coating to bacterial growth, the greater the amount of H2O2 production. In addition, the bacterial survival rates on the surfaces of coatings were almost zero when H2O2 was produced in amounts greater than 10(-6) mmol/cm2. However, the dominant concentrations of metal ions dissolved from coatings were outside of the bacterial lethal range.

Corrosion↗

PubMed1997

Phytosulfokine-alpha, a sulfated pentapeptide, stimulates the proliferation of rice cells by means of specific high- and low-affinity binding sites.

Peptide growth factors were isolated from conditioned medium derived from rice (Oryza sativa L.) suspension cultures and identified to be a sulfated pentapeptide [H-Tyr(SO3H)-Ile-Tyr(SO3H)-Thr-Gln-OH] and its C-terminal-truncated tetrapeptide [H-Tyr(SO3H)-Ile-Tyr(SO3H)-Thr-OH]. These structures were identical to the phytosulfokines originally found in asparagus (Asparagus officinalis L.) mesophyll cultures. The pentapeptide [phytosulfokine-alpha (PSK-alpha)] very strongly stimulated colony formation of rice protoplasts at concentrations above 10(-8) M, indicating a similar mode of action in rice of phytosulfokines. Binding assays using 35S-labeled PSK-alpha demonstrated the existence of both high- and low-affinity specific saturable binding sites on the surface of rice cells in suspension. Analysis of [35S]PSK-alpha binding in differential centrifugation fractions suggested association of the binding with a plasma membrane-enriched fraction. The apparent Kd values for [35S]PSK-alpha binding were found to be 1 x 10(-9) M for the high-affinity type and 1 x 10(-7) M for the low-affinity type, with maximal numbers of binding sites of 1 x 10(4) sites per cell and 1 x 10(5) sites per cell, respectively. Competition studies with [35S]PSK-alpha and several synthetic PSK-alpha analogs demonstrated that only peptides that possesses mitogenic activity can effectively displace the radioligand. These results suggest that a signal transduction pathway mediated by peptide factors is involved in plant cell proliferation.

Binding Sites↗

PubMed1997

Polysaccharide of Astragali radix enhances IgM antibody production in aged mice.

The effect of Astragali Radix (AR) on IgM antibody production in mice of various ages (10 weeks, 36 weeks and 60 weeks) was examined. The antibody production levels in the 36- and 60-week-old mice were significantly decreased to about 70 and 60% of that in the 10-week-old mice. The enhancement effect of a crude polysaccharide AR fraction on the antibody production was nil in the 10-week-old mice, but significant enhancement effects were observed in the 36- and 60-week-old mice, compared to the age-matched control. Two polysaccharides active in the enhancement of the IgM antibody production in the aged mice were isolated from the high molecular weight fraction of AR by cetavlon precipitation, ion-exchange and gel permeation chromatography. The molecular masses of these polysaccharides were calculated by HPLC in salt solution. Only one major peak was observed for each, and their molecular masses were estimated to be 1.2 x 10(4) and 2.2 x 10(4). The major components of these polysaccharides were neutral carbohydrates (89.3 and 95.5%), followed by uronic acid and protein; glucose was the predominant sugar component.

Aging↗

PubMed1997

Biological activity of purpurogallin.

Purpurogallin showed antibacterial activity toward gram-positive bacteria. Strong activity against methicillin-resistant Staphylococcus aureus [minimal inhibitory concentration (MIC) against methicillin of 1600 micrograms/ml] was found, with MIC of 11.0 micrograms/ml. Purpurogallin inhibited the growth of all tested plants and decreased the chlorophyll content in the cotyledons of Brassica campestris subsp. rapa. It showed potent inhibitory activity against prolyl endopeptidase (the 50% inhibitory concentration was 1.6 x 10(-5) M), unlike its analogues, hinokitiol and tropolone.

Anti-Bacterial Agents↗

PubMed1997

[Cerebral sinus thrombosis in a patient with protein S deficiency: a case report].

Cerebral sinus thrombosis associated with protein S deficiency is rare to the best of our knowledge. We report here a 22-year-old female who presented sudden onset of headache, vomiting and disturbance of consciousness. Neuroradiological studies including computed tomography scan, magnetic resonance imaging and cerebral angiography disclosed a huge cerebral sinus thrombosis in the territory of the superior sagittal sinus, torcular herophili, lateral sinus and straight sinus. Hematological studies confirmed the diagnosis of protein S deficiency. We summarize the reported cases of cerebral sinus thrombosis associated with protein S deficiency. For young patients presenting occlusive cerebrovascular disease, we stressed the importance of doing extensive hematological investigation to detect possible etiological factors, such as protein S deficiency, protein C deficiency, antithrombin III deficiency. Once we discover the etiology of a disease, we may be able to designate the precise treatment or regimen for each patient.

Adult↗

PubMed1996

Active fragments and analogs of the plant growth factor, phytosulfokine: structure-activity relationships.

Sulfated pentapeptide phytosulfokine-alpha (PSK-alpha) is the first chemically characterized peptidal plant growth factor that induces proliferation of the mesophyll cells of asparagus. To determine the active core involved in the sequence PSK-alpha, we synthesized PSK-alpha and twelve PSK-alpha analogs by the solid phase peptide synthesis and the direct sulfation to the peptide-resin using dimethylformamide-sulfurtrioxide (DMF-SO3) complex. The truncated analogs of PSK-alpha without the first and second C-terminal amino acids retained 8% and 20% of the activity of the parent pentapeptide, respectively. Deletion of the sulfate groups of Tyr1 and Tyr3 resulted in compounds with 0.6% and 4% of the activity of PSK-alpha, indicating that the sulfate group of Tyr1 is more important than that of Tyr3 for the expression of its activity. In contrast, the N-terminal truncated analog and unsulfated analog exhibited little or no activity. Thus the N-terminal tripeptide fragment H-Tyr(SO3H)-Ile-Tyr(SO3H)-OH has been identified as the active core of PSK-alpha.

Amino Acid Sequence↗

PubMed1996

Phytosulfokine, sulfated peptides that induce the proliferation of single mesophyll cells of Asparagus officinalis L.

Proliferation of dispersed plant cells in culture is strictly dependent on cell density, and cells in a low-density culture can only grow in the presence of conditioned medium (CM). No known plant hormones have been able to substitute for CM. To quantify the mitogenic activity of CM, we examined conditions for the assay system using mechanically dispersed mesophyll cells of Asparagus officinalis L. and established a highly sensitive bioassay method. By use of this method, the mitogenic activity of CM prepared from asparagus cells was characterized: it was heat-stable, susceptible to pronase digestion, and resistant to glycosidase treatment. On the basis of these results, the mitogenic activity in CM was purified 10(7)-fold by column chromatography, and two factors named phytosulfokine-alpha and -beta (PSK-alpha and PSK-beta) were obtained. By amino acid sequence analysis and mass spectrometry, the structures of these two factors were determined to be sulfated pentapeptide (H-Tyr(SO3H)-Ile-Tyr(SO3H)-Thr-Gln-OH) and sulfated tetrapeptide (H-Tyr(SO3H)-Ile-Tyr(SO3H)-Thr-OH). PSK-alpha and PSK-beta were prepared by chemical synthesis and enzymatic sulfation. The synthetic peptides exhibited the same activity as the natural factors, confirming the structure for PSK-alpha and PSK-beta mentioned above. This is the first elucidation of the structure of a conditioned medium factor required for the growth of low-density plant cell cultures.

Amino Acid Sequence↗

PubMed1996

Protective effect of astragali radix by oral administration against Japanese encephalitis virus infection in mice.

We investigated the protective effect of Astragali Radix (AR) by oral administration against Japanese encephalitis virus (JEV) infection in mice, the pharmacological effects of AR extracts (AE) in different origin, and the chemical composition of the AEs. A protective effect was demonstrated in all four AEs used, however, the effective grade for each one was different. In the control group, an increase of hemagglutination inhibition (HI) antibody titer was observed in all mice surviving 25 d after JEV inoculation. However, the increase of HI antibody titer was not observed in some animals administered an AE. In the control group, the rate of HI antibody positive mice was 90% 3 d after JEV inoculation, while the four groups which received the AE had a 30-60% positive rate. In mice which received the AE, the peritoneal exudate cell (PEC) numbers increased significantly compared to the control group. The predominant cell population of PECs in mice receiving the AE was macrophages, and in the PEC, the active oxygen (AO) production was high. From these results, we propose that the protective effect of AE by oral administration is based on a non-specific mechanism during the early stage of infection, before shifting to antibody production, and that macrophages play an important role in this resistance to JEV infection, e.g., by inducing the production of AO. In the chemical composition of each AE, carbohydrate was the major component.

Animals↗

PubMed1996

Protective effect of Astragali Radix by intraperitoneal injection against Japanese encephalitis virus infection in mice.

We examined the protective effect of Astragali Radix extracts (AE) by intraperitoneal injection against Japanese encephalitis virus (JEV) infection in mice. A protective effect was observed by all four samples of AE used. However, the degree of effectiveness for each AE was different. The observed survival rates of the groups injected with sample A (from Shanhsi, Japanese name Sansei-syo) and sample D (from Hokkaido) extracts were higher than 80% at 21 d after JEV inoculation. The groups injected with sample B (from Hopei, Japanese name Kahoku-syo) and sample C (from Hsiahsi, Japanese name Sensei-syo) extracts had a 60% survival rate. The increase in hemagglutination inhibition antibody titer was negligible in mice that survived 21 d after JEV inoculation. The antiviral effect of AE was examined by plaque assay in vitro, but no antiviral effect was shown. In mice injected with AE, the peritoneal exudate cell (PEC) numbers increased significantly, compared to the control. In these PEC, active oxygen production was also high. Also the group as a whole displayed a high survival rate against JEV infection, these were so strong. From these results, we propose that the protective effect of AE is dependent on a non-specific mechanism during the early stage of infection, before it shifts to antibody production, and that PEC plays an important role.

Animals↗

PubMed1994

Eleven aristolochic acid derivatives from Aristolochia cinnabarina.

Three new compounds, aristolochic acid IIIa-6-O-beta-D-glucoside, cepharanone-A N-beta-D-glucoside and 2-hydroxy-8-methyloxycepharanone-A, were isolated together with eight known compounds from methanolic extracts of fresh roots of Aristolochia cinnabarina.

Aristolochic Acids↗

PubMed1994

Effect of ageing on erythrocyte aldose reductase and sorbitol dehydrogenase activity.

We measured erythrocyte aldose reductase and sorbitol dehydrogenase activity in erythrocytes in healthy individuals aged from 16 to 91 years to determine the mechanism of age-dependent sorbitol accumulation. Erythrocyte aldose reductase activity increased significantly with age but ageing had no effect on sorbitol dehydrogenase activity. Age and the aldose reductase/sorbitol dehydrogenase ratio were positively correlated. These findings suggest that an increase in the ratio of aldose reductase to sorbitol dehydrogenase may contribute to the tissue accumulation of sorbitol in the elderly and may be a mechanism of a disease that is common in elderly individuals.

Adolescent↗

PubMed1994

Effect of aging on plasma 1,5-anhydroglucitol levels in humans and rats.

Since normal reference values change with age in some clinical parameters, we measured the plasma levels of 1,5-anhydroglucitol (AG), a new marker of glycemic control in diabetes mellitus, in healthy subjects and in rats. Our results showed a significantly negative correlation of the marker with age in humans and that the plasma AG levels of older rats were markedly lower than those of younger counterparts. This remarkable reduction of AG in the older rat group can be partially explained by our finding that aged animals excreted AG more rapidly in the urine than younger ones, besides a decrease in food intake. We therefore suggest that normal clinical reference values for plasma AG levels should be modified according to age.

Adolescent↗

PubMed1994

RFLP analysis of ribosomal DNA in sibling species of spider mite, genus Panonychus (Acari: Tetranychidae).

Ribosomal DNA (rDNA) restriction fragment length of spider mites was analysed in three sibling species of genus Panonychus (P. mori, P. citri and P. ulmi) and Tetranychus urticae. Seventy-one fragments were detected by enhanced chemiluminescence (ECL) after Southern hybridization with two genomic rDNA probes of mouse. Percentages of shared fragments within species were larger than those among species, indicating that the variation of rDNAs was useful in phylogenetic studies of spider mite species. In a phenogram based on differences of the rDNA fragment length, the relationship among Panonychus species was compatible with the results of analysis based on the morphological characters.

Animals↗

PubMed1994

[Cervical spinal epidural abscess caused by methicillin-resistant Staphylococcus aureus (MRSA)].

Epidural abscess is an uncommon infectious disease. The cervical spine is the least frequent site of spinal epidural abscess. It has been reported that early diagnosis and surgical treatment prevent neurological deficit, but it is difficult to diagnose this disease clinically. We presented a rare case of cervical epidural abscess caused by MRSA. A 54-year-old man was admitted to our hospital because of acute renal failure and hepatitis. He was treated with hemodialysis via the femoral route. His renal function recovered but high fever continued. MRSA was identified from the AV shunt catheter. He noted pain and dysesthesia on his left shoulder one month after admission. He was transferred to our department with suspect of spinal tumor. Neurological examination demonstrated left hemiparesis with superficial sensory disturbance between C8 and Th2. Cervical CT scan showed osteomyelitis at the left C7 lamina and facet. MR imaging disclosed that an epidural mass at C7 had low signal intensity on T1 weighted and high signal intensity on T2 weighted and ring-like enhancement with gadolinium. He was treated conservatively for a month. Sequential MR imaging showed the mass had homogeneous enhancement at C7 epidural space extending to the left intervertebral foramen. Laboratory examination showed normal. The patient was diagnosed as having cervical epidural abscess. A C6 through Th2 laminectomy and C8 foraminotomy were performed and an encapsulated abscess including yellowish pus was totally removed. The pathological diagnosis was non-specific abscess in the subacute stage. MRSA was identified by the intraoperative pus culture. After the surgery, antibiotics were administered.(ABSTRACT TRUNCATED AT 250 WORDS)

Abscess↗