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Biomedical subjects

H Yamaguchi

Publications and source records attributed to H Yamaguchi.

At least 829 records · Page 46Linked to original sources
PubMed1994

Flow velocity in carotid artery in humans during immersions and underwater swimming.

Heart rate and flow velocity in the common carotid artery were examined on eight subjects in various underwater conditions. The heart rate decreased more markedly during whole-body immersion than during head-out immersion. The end-diastolic flow velocity and the flow-velocity integral in a cardiac cycle during whole-body immersion increased more markedly than during head-out immersion. Differences in heart rate and flow velocity were not detected between sitting and prone positions in whole-body immersion. Heart rate increased at the beginning and after underwater swimming. The peak systolic flow velocity increased significantly after the end of underwater swimming. The flow-velocity integral in a cardiac cycle decreased during underwater swimming, but in a minute did not change significantly. These results suggest that facial immersion is important in eliciting pronounced carotid artery flow-velocity response in addition to the heart-rate response and that underwater exercise influences these responses. However, underwater posture apparently does not influence them.

Adult↗
PubMed1994

[Various factors influencing in vitro antifungal activities of omoconazole nitrate (OMZ), a new imidazole antimycotic].

Effects of various factors on in vitro antifungal activities of omoconazole nitrate (OMZ) were investigated with bifonazole (BFZ) as the reference drug using an agar dilution method and a broth dilution method. Composition of the culture medium significantly altered the activity as determined by minimum inhibitory concentration (MIC) of OMZ; OMZ exhibited a greater anti-Candida activity (smaller MIC values) on casitone agar (CA) than on Sabouraud dextrose agar (SDA). Anti-Candida activity of OMZ was the highest in pH 5 medium, but it was lowered by an increase of inoculum size, a prolongation of the incubation period and the addition of calf serum to the medium. Anti-Trichophyton activity of OMZ was not influenced with these factors except for the addition of calf serum. The activity of OMZ was fungicidal against Candida at pH 5.0 and against Trichophyton at pH 5.0 and 6.6. The geometric mean MIC of OMZ was lower than that of BFZ against C. albicans freshly-isolated on acid CA.

Antifungal Agents↗
PubMed1994

[Prophylactic effect of oral terbinafine on the development of infection in guinea pigs inoculated with Trichophyton mentagrophytes].

Prophylactic effect was studies of a novel oral antifungal agent terbinafine (TBF) on the development of local infection in guinea pigs after inoculation of Trichophyton mentagrophytes. TBF was administered orally in a single dose of 6.25 or 12.5 mg/kg, 8, 24, 48 or 72 hrs before the inoculation, and the drug effect was assessed on the basis of local symptoms and culture study. The result of experiments demonstrated that oral TBF more or less prevented the development of the dermatophytic infection, depending on the dosage and the timing of administration, the complete prevention was achieved in the animals that were administered with 12.5 mg/kg of TBF 24 hrs prior to the inoculation of T. mentagrophytes. This suggests a good transferability and intracutaneous retaining of orally administered TBF.

Administration, Oral↗
PubMed1994

[Cross-resistance of Candida albicans to several different families of antifungals with ergosterol biosynthesis-inhibiting activity].

Using 9 strains of Candida albicans mutants resistant to either a triazole-antifungal vibunazole, an imidazole-antifungal ketoconazole or a morpholine-antifungal amorolfine, experiments were conducted to see whether cross-resistance was developed to any of these 3 different families, as well as to an allylamine-antifungal terbinafine. All four compounds are known to selectively inhibit fungal ergosterol biosynthesis. All the mutant strains were found to be more or less resistant to other families of ergosterol biosynthesis inhibitors but not to terbinafine.

Antifungal Agents↗
PubMed1994

Hepatocellular carcinoma with splenic metastasis developing after 16 years of chemotherapy for chronic myelogenous leukemia: a case report.

A case of hepatocellular carcinoma (HCC), which developed during chemotherapy for chronic myelogenous leukemia (CML), is presented. A 55-year-old Japanese man, who had received an alkylating agent for 16 years, was diagnosed as having HCC with clinically evident splenic metastases. The patient died of the HCC rupture three months after diagnosis. The autopsy revealed the HCC to have developed from the non-cirrhotic liver. In the present case, DNA damage due to the long-term chemotherapy with the alkylating agent for CML may have endowed the HCC induced by post-transfusion hepatitis and alcohol abuse with an aggressive proliferative potential. This is the first report on HCC in association with CML.

Busulfan↗
PubMed1994

[A case of idiopathic chylothorax--successful pleurodesis with OK-432].

A 73-year-old woman was referred to our hospital because of left pleural effusion. Chyle was obtained by thoracocentesis. Because there was no organic lesion to cause chylothorax, idiopathic chylothorax was diagnosed. Her condition improved by chest-tube drainage and pleurodesis with intrapleural injection of OK-432. We report a rare case of idiopathic chylothorax and conclude that pleurodesis with intrapleural injection of OK432 is very useful for the treatment of idiopathic chylothorax.

Aged↗
PubMed1994

[Measurement of serum free thyroxine concentrations using anti-T4 monoclonal antibody].

A new one-step radiolabeled antibody radioassay for measuring free T4 (FT4) in serum (Amerlex-MAB FT4) was evaluated in comparison with an analog tracer RIA of FT4 (Amerlex-M FT4). In this new method, 125I-labeled anti-T4 monoclonal antibody which has cross-reactivity with T3 is used as a tracer. When incubated with serum sample, the tracer binds to FT4 and the remaining tracer binds to a T3 coated particle (Amerlex MAB). The radioactivity bound to Amerlex MAB is measured. Counts of 125I bound to the T3 coated particle were inversely proportional to sample FT4 concentrations. The assay procedure is as follows. Fifty microliter of patient's serum or standard FT4, 500 microliters of Amerlex MAB and tracer is incubated at 37 degrees C for 30 minutes and centrifuged. Then the radioactivity of Amerlex MAB is measured using an autowell gamma counter. The intra-and interassay coefficients of variation were 1.6-2.7% and 2.6-8.0%, respectively. Although Amerlex-M FT4 values were significantly increased by adding human albumin to the serum, Amerlex-MAB FT4 values were not effected by the change of albumin concentrations. In nonthyroidal illness patients, Amerlex-MAB FT4 values were not affected by the concentrations of albumin, TBG and NEFA. The euthyroid central 95% reference range for FT4 determined by Amerlex-MAB FT4 was 0.99 to 1.54 ng/dl. The FT4 levels correlated well with the metabolic status. Although Amerlex-M FT4 values were spuriously increased in patients with anti-T4 autoantibodies, Amerlex-MAB FT4 values were not affected by the autoantibodies. Amerlex-MAB FT4 values of normal pregnant women were slightly lower in the second and third trimesters than in the first trimester. These lower FT4 concentrations in late pregnancy were considered likely not to be artefact by low serum albumin or high serum TBG but to be a physiological event. Amerlex-MAB FT4 values correlated well with FT4 indices and inversely correlated with TSH levels. A significant correlation (n = 401, r = 0.86, p = 0.0001) was observed between Amerlex-MAB FT4 and Amerlex-M FT4 values in various thyroid conditions without antithyroid autoantibodies. In summary, this new assay for FT4 is simple, rapid and reproducible. The measurement is useful for the evaluation of physiological thyroid function and helpful in the management of patients with thyroid diseases.

Adult↗
PubMed1993

Flexibility impaired by mutations revealed the multifunctional roles of the loop in glutathione synthetase.

The loop from Ile-226 to Arg-241 in the glutathione synthetase (GSHase) from Escherichia coli B is rich in glycine and alanine and too flexible to take a fixed conformation [Yamaguchi, H., Kato, H., Hata, Y., Nishioka, T., Kimura, A., Oda, J., & Katsube, Y. (1993) J. Mol. Biol. 229, 1083-1100; Tanaka, T., Kato, H., Nishioka, T., & Oda, J. (1992) Biochemistry 31, 2259-2265]. To restrict the flexibility, three residues in the loop, Pro-227, Gly-229, and Gly-240, were replaced with alanine and valine residues. Variability in conformations of the mutant loops and shifts in the distribution of conformers between the open and closed states were assessed by steady-state kinetics, X-ray crystallographic structure analysis, and proteolysis with arginyl endopeptidase. Mutant enzymes replaced with a valine residue at the basal positions of the loop (P227V, G240V, and P227V/G240V) were identical with the wild-type enzyme in their crystal structures, except the loop region. The mutant loops retained apparent conformational variability, so as to take the open and closed states and to protect the acyl phosphate intermediate from the decomposition uncoupled from glutathione synthesis, but lost the catalytic activity; Kmapp values for glycine and gamma-Glu-Cys were sensitive to the mutations and drastically increased, and the k0app value was fatally reduced in the P227V/G240V mutant enzyme. The present results suggest that adjustability of the loop to the closed state is required for the recognition of the substrates, gamma-Glu-Cys and glycine, and for the chemical interactions with the bound substrates.

Amino Acid Sequence↗
PubMed1993

Natural killer cells induce activated murine B cells to secrete Ig.

We previously demonstrated that dextran-conjugated anti-IgD antibodies (alpha delta-dex) induce proliferation of small, B cell-enriched murine spleen cells (Be cells), and in the presence of IL-2, stimulate Ig secretion in vitro. We have shown that alpha delta-dex-stimulated B cells provide an in vitro model for studying B cell activation by T cell-independent type 2 (TI-2) Ag, as exemplified by the bacterial polysaccharides. We now show that highly purified resting B cells, obtained by electronic cell sorting (Bsp cells), fail to secrete Ig in the presence of alpha delta-dex + IL-2. The alpha delta-dex + IL-2-induced Ig secretory response of Bsp cells is restored upon addition of splenic non-B, non-T cells or a pure population of in vitro-generated NK cells. Similarly, pretreatment of Be cells with anti-AsGm-1 plus complement inhibits Ig secretion in response to alpha delta-dex + IL-2. An IL-2-induced NK cell supernatant (NKSN) is equally potent at stimulating Ig secretion by alpha delta-dex-activated Bsp cells, indicating that cell contact between Bsp and activated NK cells is not required for this effect. IL-2 stimulates not only NK cells, but B cells as well, since addition of anti-IL-2 + anti-IL-2R antibodies to Bsp cell cultures, in the presence of alpha delta-dex + NKSN, inhibits Ig secretion. These data describe a novel animal model for NK cell-induced B cell maturation to Ig secretion and suggest a pathway for Ig production in response to T1-2 Ag.

Animals↗
PubMed1993

Flash induced XANES spectroscopy for the Ca-depleted Mn-cluster in the photosynthetic O2-evolving enzyme.

Flash-induced changes of the Mn K-edge absorption spectra have been studied in the oxygen-evolving complex depleted of Ca. The Mn K-edge energy for the Ca-depleted S1-state was lower by 1.5 eV than that for the normal S1-state. The K-edge energy upshifted by 1 eV after one flash, indicative of an oxidation of Mn. After two flashes, the K-edge was elevated as well by 0.4 eV, and then reached a steady-state high level after continuous illumination where the K-edge energy was higher by 0.9 eV than that after one flash. The results indicate that the Mn-cluster and/or its direct ligand could be oxidized up to two electrons but further events are blocked.

Calcium↗
PubMed1993

DM-9384, a new cognition-enhancing agent, increases the turnover of components of the GABAergic system in the rat cerebral cortex.

DM-9384 (nefiracetam) (N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide), a pyrrolidone derivative (or a cyclic derivative of gamma-aminobutyric acid (GABA)), is a newly developed nootropic (or cognition-enhancing) agent. In the present study, we examined the biochemical effect of DM-9384 on GABAergic neurons in adult rat brains. DM-9384, when administered orally at a daily dose of 10 mg/kg for 7 days, significantly increased GABA turnover and glutamic acid decarboxylase activity in the cortex and hippocampus, and stimulated Na(+)-dependent high-affinity GABA uptake in cortical synaptosomes. In in vitro experiments, the K(+)-evoked release of [14C]GABA from cortical slices was markedly increased by low concentrations (10(-8), 10(-9) M) of DM-9384. The binding of GABAA and benzodiazepine to their receptors in the brain was not affected by DM-9384 (10(-10)-10(-3) M). The results suggest that DM-9384 increases the turnover of components of the GABAergic system by influencing presynaptic sites rather than postsynaptic sites.

Administration, Oral↗
PubMed1993

Immunomodulating activity of antifungal drugs.

1. The immunomodulating activity of antifungal drugs was reviewed. Although results are conflicting, all azole drugs tend to be immunosuppressive, except for fluconazole, which has no immunologic effect. In contrast, the polyene antibiotic amphotericin B (AMPH) is immunostimulatory. 2. AMPH induced host resistance to Pseudomonas aeruginosa infection in mice, whereas no azole drugs did so. 3. Polymorphonuclear leukocytes are activated by AMPH, but not by any azole drugs, in terms of the level of their adherence. 4. No azole drugs induce in vitro tumor necrosis factor alpha (TNF) production by macrophages, whereas AMPH slightly but substantially does so. 5. AMPH potently primes macrophages in vitro and in vivo so that they produce large amounts of TNF after the secondary stimulation (triggering) by bacterial lipopolysaccharides or a streptococcal preparation used for antitumor immunotherapy, OK432. 6. Viable or heat-killed Candida albicans cells are capable of inducing in vitro TNF production by macrophages. This activity of the fungal cells is enhanced by AMPH.

Adjuvants, Immunologic↗
PubMed1993

Characterization of the preparation process and the photochemical control of electrical properties of bilayer lipid membranes containing azobenzene chromophores.

We prepared photoresponsive bilayer lipid membranes (BLMs) containing azobenzene derivatives (4'-octylazobenzene-4-oxybutyric acid (AZ)) and observed the rapid and reversible changes in their electrical properties when irradiated with light. The BLMs consist of AZ (8 mol%) and glyceryl monooleate. The changes in capacitance and conductance upon irradiation by light were found to be 10 and 20%, respectively. The changes in the electrical properties of the membrane and in the structure of AZ under light irradiation were analyzed simultaneously by in-situ spectroscopic, electrical and microscopic measurements. These measurements showed that the electrical changes induced by exposure to light resulted from reversible changes in the membrane structure initiated by the photoisomerization reaction of AZ. This structural change in the membrane occurred within 1 s.

Azo Compounds↗
PubMed1993

Amyloid beta protein precursor accumulates in swollen neurites throughout rat brain with aging.

We immunocytochemically studied the expression of amyloid beta protein precursor (APP) in the brains of normal aged rats, and found APP accumulation in swollen neurites, most of which were axons. These swollen neurites appeared throughout the central nervous system of aged rats; most of them were negative for neurofilament, ubiquitin, and tau. Such widely distributed APP accumulation in swollen neurites may reflect impaired fast axonal transport due to aging. APP immunostaining may be a good method to detect widely distributed age-related changes.

Aging↗
PubMed1993

IL-10 inhibits T cell-independent but not T cell-dependent responses in vitro.

Lymphokines play a key role in T cell-independent (TI) Ag-induced responses. We recently showed that IL-10 potently inhibits Ig production stimulated by TI-2 Ag + IL-5. In view of our recent findings that the B cell activator can determine the effect lymphokines will have on Ig production and on isotype selection, we analyzed the effect of IL-10 on Ig production induced by other TI antigens and T cell-dependent Ag. These data demonstrate that IL-10 inhibited IL-5-induced Ig production stimulated by TI-1 and by TI-2 Ag, but had no effect on an in vitro T cell-dependent Ag-specific anti-SRBC-induced response or on a T cell-induced polyclonal response mediated by anti-CD3-activated T cell clones. IL-10 inhibited IgM, IgG1, IgG2a, and IgG3 secretion by B cells costimulated by LPS or anti-delta-dextran. IL-10 did not interfere with induction of class II MHC Ag expression or cell enlargement that was stimulated by LPS or anti-delta-dextran and had no detrimental effect on cell viability. IL-4 reversed the IL-10-mediated inhibition of IgG1 and IgM secretion stimulated by anti-delta-dextran or LPS-activated cells in the presence of IL-5. A 72 h, but not 24 h, exposure to IL-4 at initiation of culture with anti-delta-dextran + IL-5 + IL-10 was necessary to reverse the IL-10-mediated inhibition of IgM secretion. Our data suggest that IL-10 can selectively inhibit TI Ag-induced responses when other T cell-derived stimulatory lymphokines are not present and further emphasize the specific role of the B cell activator in influencing the responsiveness of B cells to lymphokines.

Animals↗