Biomedical subjects

Yutaka Tajima

Publications and source records attributed to Yutaka Tajima.

5 recordsLinked to original sources

PubMed2003

The effects of tungstophosphate and tungstosilicate on various stress promoters transformed in Escherichia coli.

Although tungsten is an important material in some industrial and chemical processes, the biological and biochemical effects, including the toxicity, of tungsten compounds are not known well. In this study, a reporter gene assay using special strains of Escherichia coli was performed to investigate the mode of action of two polyoxotungstates, i.e. undecatungstophosphate (PW(11)) and undecatungstosilicate (SiW(11)). When the bacterial cells were cultured with PW(11), osmY (a stress promoter gene sensitive to osmotic signals) was induced to some extent, while other stress promoters were expressed only slightly. SiW(11) gave similar results, but clpB (an analogue of human heat shock protein) was more strongly induced. It is possible that PW(11) and SiW(11) can produce an osmotic signal at lower concentrations without increasing ionic strength. Since the constituents of PW(11)/SiW(11) (i.e. HPO(4)(2-), SiO(3)(2-), WO(4)(2-)) showed almost no effect, a chemical feature unique to PW(11)/SiW(11) and originating from neither of their constituents, i.e. a polyanionic characteristic, may play an important role in their biological effects.

Escherichia coli↗

PubMed2003

Effects of tungstosilicate on strains of methicillin-resistant Staphylococcus aureus with unique resistant mechanisms.

In a previous study, it was found that polyoxotungstates such as undecatungstosilicate (SiW11) greatly sensitized strains of methicillin-resistant Staphylococcus aureus (MRSA) to beta-lactams. In this report, the effects of SiW11 on several MRSA strains with unique resistant mechanisms were studied. SiW11 was still effective to MRSA mutants with higher beta-lactam resistance due to reduced cell-lytic activity. Since the antimicrobial effect of TOC-39 (a cephem antibiotic with strong affinity to penicillin-binding protein (PBP) 2') was not strongly enhanced in any case, it was confirmed that the sensitizing effect of SiW11 is due to reduced expression of PBP2'. However, the sensitizing effect of SiW11 was relatively weak in MRSA strains with lowered susceptibility to glycopeptide antibiotics. A certain resistant mechanism other than the mecA-PBP2' system worked in such a strain. Interestingly, an MRSA mutant with the Eagle-type resistance was dramatically sensitized. This result suggests that SiW11 has another site of action besides reducing the expression of PBP2'.

Anti-Bacterial Agents↗

PubMed2003

[A hypothesis about anti-DNA antibody].

"Anti-DNA antibody" is the antibody which can bind DNA molecules. It is well accepted that this antibody, especially in anti-double strand DNA antibody, has a high disease specificity for SLE. Usually, the antibody is detected by using DNA molecule as a binding target in the clinical laboratory test performed in vitro. However, it is quite unknown what the antibody is actually attacking in vivo. This review will introduce many findings known to date and try to solve the mystery of anti-DNA antibody with a hypothesis that the antibody nonspecifically crossreacts to negatively charged substances(e.g., polysaccharides) in vivo. Probably, a type of charge interaction is dominantly involved in this binding.

Autoantibodies↗

PubMed2002

[Unexpected drug-interaction].

The case of a male patient suffering from chronic normal pressure hydrocephalus is outlined. Antidepressant and pravastatin were administered because of the patient's abulia and hypercholesterolemia, but neuroleptic malignant syndrome-like conditions developed. All physicians should suppose the occurrence of such an "unexpected drug-interaction" in any case. The author considered that a good sense of careful discernment and rapid reference system of medical information are "essential tools" for clinical management.

Aged↗

PubMed2002

[Undecatungstophosphate sensitized strains of methicillin-resistant Staphylococcus aureus to beta-lactams].

Previously, a factor (Factor T) was found in aged mixtures of tungstate and phosphate, which greatly sensitizes strains of methicillin-resistant Staphylococcus aureus to beta-lactams. Factor T was purified and identified as undecatungstophosphate([PW11O39]7-). Undecatungstosilicate([SiW11O39]8-), a compound closely related to undecatungstophosphate, showed a similar enhancing effect. Chemically, these compounds are classified as "polyoxotungstates", and it is expected that these tungsten compounds will be useful as a "tool" in laboratory tests: i.e., in screening media for highly resistant MRSA strains. They may be also useful to investigate the resistant mechanism of the bacterial cells.

Anti-Bacterial Agents↗