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Biomedical subjects

K Nagai

Publications and source records attributed to K Nagai.

At least 109 records · Page 6Linked to original sources
PubMed2001

A comparative study of characteristics of current-type and conventional-type cationic bactericides.

We have synthesized new polycationic bactericides, polyloxyethylene(dimethyliminio)trimethylene(dimethyliminio)ethylene dichloridel (OXD) and poly(hexamethyleneguanidine phosphate) (HEP), in order to develop more active but less skin-irritative bactericides. The effects of these bactericides on Pseudomonas aeruginosa, Escherichia coli, Serratia marcescens, Klebsiella pneumoniae, methicillin resistant Staphylococcus aureus (MRSA) and the degree of their irritations on skin were compared with those of a widely used low molecular-weight cationic bactericide, benzalkonium chloride (BAC), and a polycationic bactericide, poly[2-hydroxyethylene(dimethyliminio)methylene chloride] (2HYC). The minimum bactericidal concentration (MBC) of OXD for 10 min contact incubation was 16 microg/ml against P. aeruginosa, E. coli, S. marcescens and K. pneumoniae, and >1000 microg/ml against MRSA. The MBC of HEP for 10 min contact incubation was 16 microg/ml against P. aeruginosa, 32 microg/ml against E. coli and K. pneumoniae, and 64 microg/ml against S. marcescens and MRSA. Itch, edema, erythema, heat, injury, desquamation and keratinization caused by skin irritation were examined in 21 subjects by patch tests. Only one subject treated with OXD experienced edema, and one subject with HEP experienced keratinization. However, BAC caused itch in 3 subjects, edema in 1, erythema in 10 and desquamation in 2, indicating that the incidence of skin irritation of BAC was higher than that of OXD or HEP. OXD and HEP had sterilization ability similar to BAC, however, they were less skin-irritative than BAC. This indicates that OXD and HEP can be used as safe bactericides.

Adult↗
PubMed2001

Contribution of specific transport systems to anthracycline transport in tumor and normal cells.

Anthracycline antibiotics are very effective neoplastic agents widely used clinically. However, because of their many adverse effects (e.g. cardiotoxicity, leukopenia and alopecia), their clinical use has been limited. In order to minimize their adverse effects in clinical cancer chemotherapy, anthracyclines must be selectively transported into tumor cells. If there are differences in transport characteristics between tumor and normal cells, it should be possible to establish a strategy for selectively delivering anthracyclines to tumor cells on the basis of the differences. In human cultured leukemia HL60 cells, as tumor cells, and human fresh mononuclear cells, as normal cells, doxorubicin, pirarubicin, daunorubicin and idarubicin were incorporated via a common carrier-mediated system, but the carriers were different in the two cell types. In HL60 cells, it was indicated that a nucleoside transport system contributed, at least in part, to the transport of doxorubicin and pirarubicin, but not daunorubicin and idarubicin, and its contribution to pirarubicin transport was found in other tumor cells, i.e. mouse ovarian sarcoma M5076 and Ehrlich ascites carcinoma cells. On the other hand, in mononuclear cells, there was no involvement of a nucleoside transport system for the four anthracyclines examined. Therefore, we thought that with the modification of an anthracycline molecule as a substrate for the nucleoside transport system, the anthracycline could be delivered selectively to tumor cells.

Animals↗
PubMed2001

Neuroprotectins A and B, bicyclohexapeptides protecting chick telencephalic neuronal cells from excitotoxicity. I. Fermentation, isolation, physico-chemical properties and biological activity.

Glutamate, an excitatory amino acid, is known to induce neurotoxicity in central nervous system under abnormal conditions such as ischemia, hypoglycemia, epilepsy, Huntington's chorea, Parkinson's disease and Alzheimer's disease. In our search for neuroprotective agents of microbial origin against excitatory neurotoxins, we have isolated two new bicyclohexapeptides, neuroprotectins A and B, together with a known compound complestatin, from the fermentation broth of Streptomyces sp. Q27107. Neuroprotectins protected primary cultured chick telencephalic neurons from glutamate- and kainate-induced excitotoxicities in a dose-dependant fashion.

Animals↗
PubMed2001

Neuroprotectins A and B, bicyclohexapeptides protecting chick telencephalic neurons from excitotoxicity. II. Structure determination.

In the course of our search for neuroprotective agents of microbial origin against kainate-induced neurotoxicity, we have succeeded in the isolation of two new bicyclohexapeptides, neuroprotectins A and B, together with a known compound, complestatin, from the fermentation broth of Streptomyces sp. Q27107. They are closely related in structure to complestatin and possess an oxindolylalanine moiety in place of the tryptophan residue present in complestatin.

Molecular Structure↗
PubMed2001

[Functional relationship between circadian rhythm and control of food intake].

Living things on the earth including bacteria, plants and animals show circadian rhythms in their behaviors and physiological phenomena, and these circadian rhythms are usually synchronized with environmental changes having the period of 24 h on the earth. In mammals including human beings, the hypothalamic suprachiasmatic nucleus (SCN) functions as a master circadian oscillator, and generates a circadian rhythm of food intake. Sometimes the circadian oscillation of the SCN is disturbed with physical and psychological stressors. This review describes the functional relationship in respect to connections between the circadian oscillator in the SCN and food regulatory centers and neurons in the brain focusing on its mechanism in human beings, and a possible involvement of the circadian oscillator of the SCN in the abnormality of the appetite control.

Animals↗
PubMed2001

[Influence of cyclosporin on steroid-induced cataract].

PURPOSE: To study the effect of cyclosporin on steroid-induced cataract in patients after renal transplantation. SUBJECTS AND METHODS: 140 patients who received renal transplantation and ophthalmological examinations before and over 12 months after surgery at Kanazawa Medical University were investigated retrospectively. The subjects were divided into the following two groups: the conventional therapy group(Group C) who were administered azathioprin and methylprednisolone and the triple therapy group(Group T) who were administered azathioprin, methylprednisolone and cyclosporin. There were 73 subjects in group C and 67 in group T. Judgement of steroid cataract followed Crew's classification and steroid cataract was diagnosed when vacuoles or opacity were seen in the posterior subcapsular region. Subjects that had any lens opacity before renal transplantation were excluded. RESULTS: The total dose of systemic steroid during the first year and in the final observation period in group T was significantly higher than in group C. The prevalence of steroid cataract was 55% and 63% for the 1st year, 72% and 89% for the 2nd year, 74% and 92% for the 3rd year and 83% and 96% for the 5th year in groups C and T, respectively. By the third year, the rate of subjects whose corrected visual acuity was less than 0.8 or who received cataract surgery was significantly higher in group T than in group C. There was no significant difference in the total dose between the subjects with cataract over grade I and those of grade 0 and I in both groups C and T. In group C, the total dose of steroid pulse therapy was significantly higher in the subjects with steroid cataract over grade I than in those with grade 0 and I. CONCLUSIONS: Using cyclosporin, although the total dose of systemic steroid was decreased, the rate of steroid cataract increased. Cyclosporin may accelerate the development of steroid cataract. Steroid pulse therapy is considered to be a risk factor for developing steroid cataract.

Adolescent↗
PubMed2001

[Whole-body MR imaging for evaluation of bone marrow cellularity in aplastic anemia].

The aim of this study was to investigate the usefulness of whole-body MRI(WB-MRI) in the evaluation of cellularity in bone marrow and the distribution of fatty marrow in aplastic anemia. WB-MRI was performed on five patients with aplastic anemia who ranged in age from 62 to 70 years of age, and on four controls with malignant lymphoma who ranged in age from 59 to 67 years. Coronal images were obtained using a body coil with an FOV of 48 cm x 48 cm, and with both fast short T1 inversion recovery(STIR) and spin-echo T1-weighted(T1-WI) in three regions: (1) head to thorax, (2) abdomen to pelvis, and (3) lower extremities. The findings on WB-MRI were compared with those of histological studies of bone marrow at the sternum and the posterior iliac crest. The results were as follows: (1) there was a correlation between the cellularity of histological studies of bone marrow and signal intensity on WB-MRI; (2) WB-MRI could detect the activity of bone marrow; and (3) in a comparison of signal intensity in aplastic anemia and control subjects, there were differences of signal intensity in the central marrow.

Aged↗
PubMed2001

Activity of telithromycin against 26 quinolone-resistant pneumococci with known quinolone-resistance mechanisms.

NCCLS agar dilution was used to test activity of telithromycin compared to clarithromycin, penicillin G, ciprofloxacin, levofloxacin, sparfloxacin and moxifloxacin against 26 pneumococci with defined quinolone resistance (type II topoisomerase and efflux) mechanisms. Thirteen strains were penicillin susceptible, six intermediate and seven resistant. Clarithromycin resistance (mef and/or erm) was seen in eight strains. Ciprofloxacin MICs (mg/L) were 8-64 compared to 1-32 (levofloxacin), 0.5 . or = 32 (sparfloxacin) and 0.125-4 (moxifloxacin). Telithromycin MIC50 and MIC90 values (mg/L) were 0.016 and 0.25, with only one strain having an MIC of 2 mg/L.

Anti-Bacterial Agents↗
PubMed2001

[Diagnostic imaging of osteoporosis: special reference to diagnosis by radiography and DXA].

Primary osteoporosis is diagnosed by diagnostic criteria, eg. whether non-traumatic vertebral body is or not, or the severity of low bone mass. As a diagnostic imaging of osteoporosis, grading of radiographic osteopenia, and Singh index in the upper end of femur are well-known. Vertebral fracture associated with osteoporosis shows wedge, fish or flat deformity, but it is necessary to differentiate from Schmorl node and so on. DXA is a main stream of bone mineral quantification method, and its image is expressed the distribution of bone mineral density per unit area.

English Abstract↗
PubMed2000

Reversible and potent uncoupling of hog gastric (H(+)+K(+))-ATPase by prodigiosins.

Prodigiosin, prodigiosin 25-C, and metacycloprodigiosin all strongly inhibited the acidification activity of (H(+)+K(+))-ATPase on membrane vesicles from hog gastric mucosa (IC(50) = 32 to 103 pmol/mg protein). But, the prodigiosins, unlike omeprazole, showed little inhibitory effect on K(+)-dependent ATPase (K(+)-ATPase) activity, although at higher concentrations they inhibited K(+)-ATPase activity with an IC(50) of 1.5 to 3.0 microM. Furthermore, the inhibitory effect of the prodigiosins was rapid and completely reversible unlike that of omeprazole, and the mode of inhibition was non-competitive with respect to ATP. Hog gastric (H(+)+K(+))-ATPase itself showed an absolute requirement of halide (effectively, chloride) for acidification activity. Prodigiosins also showed a chloride requirement for inhibition of vesicular acidification, and quickly reversed the acidification of vesicular pH to neutrality even in the presence of N, N'-dicyclohexylcarbodiimide (DCCD), showing their ionophoric nature of acidification inhibitory activity. In fact, tributyltin chloride (TBT, an OH(-)/Cl(-) exchange ionophore) also inhibited vesicular acidification, but it inhibited K(+)-ATPase activity too. Finally, the prodigiosins inhibited the acid secretion from parietal cells isolated from rabbit gastric mucosa. These results suggest that prodigiosins are potent reversible uncouplers of (H(+)+K(+))-ATPase that inhibit gastric acid secretion.

Adenosine Triphosphate↗
PubMed2000

Molecular characterization and nuclear localization of rat timeless-like gene product.

Among three period genes (per1, per2, per3) in mammals, only per2 gene was shown to be involved in the core clock mechanism. To elucidate the molecular function of rat PERIOD2 (rPER2), we searched for binding proteins to the PAS domain of rPER2. We isolated a binding protein to this domain and identified it as a TIMELESS-like protein (TLP) on the basis of mass analyses. Then, we isolated a rat TLP cDNA from the rat hypothalamus library. RNA blot analysis and in situ hybridization indicates that rTLP mRNA was expressed in all rat tissues from whole brain, the suprachiasmatic nucleus, eye, lung, heart, liver, kidney, placenta, and testis. When rTLP gene product was expressed in COS-1 cells, nuclear localization of rTLP was detected in 99.6% of transfected cells. These results suggest that the interaction of rPER2 with rTLP may influence the regulation of circadian clock components in nucleus after rPER2 is translocated into the nucleus.

Amino Acid Sequence↗
PubMed2000

Prognosis of isolated systolic and isolated diastolic hypertension as assessed by self-measurement of blood pressure at home: the Ohasama study.

BACKGROUND: Although the clinical significance of systolic-diastolic hypertension and isolated systolic hypertension has been established, the significance of isolated diastolic hypertension has not been fully investigated. OBJECTIVE: To clarify the prognostic significance of isolated systolic and isolated diastolic hypertension as assessed by self-measurement of blood pressure (BP) at home (home BP measurements), which has a better reproducibility and prognostic value than casual BP measurements in the general population. SUBJECTS AND METHODS: We obtained home BP measurements for 1913 subjects aged 40 years or older, then followed up their survival status (mean, 8.6 years). We classified the subjects into the following 4 groups according to their home BP levels: systolic-diastolic hypertension, isolated systolic hypertension, isolated diastolic hypertension, and normotension. The prognostic significance of each type of hypertension for the risk of cardiovascular mortality risk was investigated using a Cox proportional hazards regression model adjusted for possible confounding factors. RESULTS: The risk for isolated systolic hypertension and systolic-diastolic hypertension were significantly higher than the relative hazard for normotension, while isolated diastolic hypertension was associated with no significant increase in risk. Home pulse pressure measurement was also independently associated with an increase in the risk of cardiovascular mortality. CONCLUSIONS: Isolated diastolic hypertension, as assessed by home BP measurements, carried a low risk of cardiovascular mortality, similar to that found in subjects with normotension, suggesting that the prognosis of hypertension would be improved by treatment focused on systolic rather than on diastolic home BP measurements. To our knowledge, this study is the first to demonstrate the clinical significance of pulse pressure as assessed by home BP measurement. Arch Intern Med. 2000;160:3301-3306.

Adult↗
PubMed2000

Dynamical quark effects on light quark masses

Light quark masses are calculated in lattice QCD with two degenerate flavors of dynamical quarks. The calculations are made with improved actions with lattice spacing a = 0.22-0.11 fm. In the continuum limit we find m(M&Smacr;)(ud)(2 GeV) = 3.44(+0.14)(-0.22) MeV using the pi and rho meson masses as physical input, and m(M&Smacr;)(s)(2 GeV) = 88(+4)(-6) MeV or 90(+5)(-11) MeV with the K or straight phi meson mass as additional input. The quoted errors represent statistical and systematic combined, the latter including those from continuum and chiral extrapolations, and from renormalization factors. Compared to quenched results, two flavors of dynamical quarks reduce quark masses by about 25%.

Journal Article↗