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Biomedical subjects

N Hirota

Publications and source records attributed to N Hirota.

At least 37 records · Page 2Linked to original sources
PubMed1999

Bactericidal activities of essential oils of basil and sage against a range of bacteria and the effect of these essential oils on Vibrio parahaemolyticus.

Basil and sage essential oils were examined for bactericidal activity against a range of Gram-positive and Gram-negative bacteria by viable count determinations. Generally, Gram-positive bacteria showed higher resistance to basil and sage essential oils than Gram-negative bacteria. Vibrio species showed a high sensitivity to both essential oils. Stationary growth phase cells of selected bacteria showed higher resistance to these essential oils than exponential growth phase cells. Basil-resistant (b21) and sage-resistant (s20) strains of Vibrio parahaemolyticus were isolated. Both strains showed higher resistance to heat and H2O2 than parent strain. Conversely, heat-adapted V. parahaemolyticus also showed a higher resistance to these essential oils than nonadapted cells.

Colony Count, Microbial↗
PubMed1998

Group additive contributions to the alcohol-induced alpha-helix formation of melittin: implication for the mechanism of the alcohol effects on proteins.

Detailed analysis of the effects of alcohols on proteins and peptides is important because of its wide range of applications in many fields. Whereas melittin, a major component of honeybee venom, is unfolded in an aqueous environment, the addition of alcohols induces an alpha-helical structure. We used circular dichroism (CD) to compare the effects of various alcohols on melittin. Whereas the alpha-helical state was basically independent of alcohol species, the effectiveness of alcohols varied significantly. Among alkanols, the effectiveness was proportional to the bulkiness of hydrocarbon groups, indicating that the hydrocarbon group contributes positively to the alcohol effects. Comparison of alcohols with the same hydrocarbon group but a different number of hydroxyl groups showed that the hydroxyl groups contribute negatively to the alcohol effects. Comparison of several halogenols indicated that halogen increases the effectiveness in the order of F < Cl < Br. These results suggested that the effects of alcohol can be interpreted by the additive contributions of each of the constituent groups of the alcohol, which are proportional to the solvent-accessible surface area. However, for markedly effective alcohols such as 1,1,1,3,3,3-hexafluoro-2-propanol, the aggregation of alcohols was suggested to further enhance these effects. We have constructed equations for estimating the effectiveness of alcohols in inducing alpha-helical structure, which should also be useful for predicting the other effects of alcohols on proteins.

Alcohols↗
PubMed1998

Application of nitrite reductase from Alcaligenes faecalis S-6 for nitrite measurement.

The enzymatic reaction of nitrite reductase (NIR) from Alcaligenes faecalis S-6 was applied to the measurement of nitrite. NIR was immobilized on the surface of a gold electrode using filter paper and a dialysis membrane, and used as a working electrode in a three-electrode system. Amperometric methods were applied using NIR and the electron mediator 1-methoxy PMS (1-methoxy-5-methylphenazinium methylsulfate). The decrease in cathodic current showed a correlation to nitrite concentration over the range 0-1 mg/l. Measurements using a batch-flow type system gave a lower detection limit of 0.01 mg/l. This is sufficient for the detection of nitrite in natural waters.

Alcaligenes↗
PubMed1998

Isolated trigeminal nerve metastases from breast cancer: an unusual cause of trigeminal mononeuropathy.

BACKGROUND: Mononeuropathy of a cranial nerve caused by brain metastases rarely occurs in patients with a malignant neoplasm. Even after the development of computed tomography (CT) and magnetic resonance imaging (MRI), few cases of brain metastases resulting in trigeminal mononeuropathy have been reported. We report a case of trigeminal mononeuropathy caused by a brain metastases that was detected on CT and MRI preoperatively, and was successfully treated by microsurgery and radiation. CASE DESCRIPTION: A 49-year-old woman with a history of breast cancer complained of right facial pain. CT and MRI revealed a brain tumor in the right Meckel's cave and cerebellopontine angle. She underwent surgery, and the diagnosis was metastatic breast cancer. No recurrence was detected on MRI performed 2 years after the resection and radiation of the tumor. CONCLUSIONS: Most of the reported cases of brain metastases causing a mononeuropathy occurred before the availability of CT; the mononeuropathy was diagnosed by neurologic or postmortem examination. Even after the development of CT and MRI, few cases of brain metastases resulting in trigeminal mononeuropathy have been reported. If such patients do not manifest symptoms of brain metastases other than the mononeuropathy, it is difficult to make the correct diagnosis without CT and MRI. Physicians must be aware of mononeuropathy as an uncommon presenting symptom of brain metastases.

Breast Neoplasms↗
PubMed1998

Angiographic documentation of de novo aneurysm--case report.

A 49-year-old female presented with a case of de novo aneurysm which was documented angiographically 10 years after the initial aneurysm rupture. The de novo aneurysm arose as a blister-like aneurysm from a previously normal location 7 years after the first ictus. The de novo aneurysm progressed to a saccular aneurysm and ruptured after another 3 years. We recommend late angiography in high-risk patients to prevent repeat ictus.

Aneurysm, Ruptured↗
PubMed1998

[Clinical efficacy of sulbactam/ampicillin in comparison with cefotiam in the treatment of elderly patients with pneumonia].

Clinical efficacy and safety of pareteral sulbactam/ampicillin (SBT/ABPC) was compared with cefotiam (CTM) in a randomized clinical trial of pneumonia in the elderly at 13 National Hospitals of Kyushu island. 37 patients received SBT/ABPC 3 g i.v., b.i.d., and 31 patients received CTM 1 g i.v., b.i.d. for 7 to 14 days. 1. 68 patients (37 for SBT/ABPC and 31 for CTM) were evaluated for safety. No statistical differences were noted in the patients' backgrounds of either group. 2. The clinical efficacy of SBT/ABPC was 96.3% (26/27 cases) while CTM was 75.2% (17/23 cases). This was found to be statistically significant (Fisher's exact test: p < 0.05). 3. 100% of evaluated cases (10 for SBT/ABPC and 4 for CTM) showed bacterial elimination. 4. No side effects were observed in the study. 5. Abnormal laboratory findings were noted in 10.8% (4/37 cases) for SBT/ABPC and 3.2% (1/31 cases) for CTM. The major adverse events were mild elevation of GOT, GPT and A1-P for SBT/ABPC, and mild platelets overproduction for CTM. No statistical differences were noted in both groups. These results are consistent with SBT/ABPC as a highly effective antibiotic in the treatment of elderly patients with pneumonia.

Aged↗
PubMed1997

Cooperative alpha-helix formation of beta-lactoglobulin and melittin induced by hexafluoroisopropanol.

Alcohols denature the native state of proteins, and also stabilize the alpha-helical conformation in unfolded proteins and peptides. Among various alcohols, trifluoroethanol (TFE) and hexafluoroisopropanol (HFIP) are often used because of their high potential to induce such effects. However, the reason why TFE and HFIP are more effective than other alcohols is unknown. Using CD, we studied the effects of TFE and HFIP as well as reference alcohols, i.e., methanol, ethanol, and isopropanol, on the conformation of bovine beta-lactoglobulin and the bee venom melittin at pH 2. Upon addition of alcohols, beta-lactoglobulin exhibited a transformation from the native state, consisting of beta-sheets, to the alpha-helical state, whereas melittin folded from the unfolded state to the alpha-helical state. In both cases, the order of effectiveness of alcohols was shown to be: HFIP > TFE > isopropanol > ethanol > methanol. The alcohol-induced transitions were analyzed assuming a two-state mechanism to obtain the m value, a measure of the dependence of the free energy change on alcohol concentration. Comparison of the m values indicates that the high potential of TFE can be explained by the additive contribution of constituent groups, i.e., F atoms and alkyl group. On the other hand, the high potential of HFIP is more than that expected from the additive effects, suggesting that the cooperative formation of micelle-like clusters of HFIP is important.

1-Propanol↗
PubMed1997

Effect of glutathione-modulating compounds on hydrogen-peroxide-induced cytotoxicity in human glioblastoma and glioma cell lines.

The relation between the intracellular glutathione (GSH) concentration and hydrogen-peroxide(H2O2)-induced cytotoxicity was investigated. The intracellular GSH concentration in human glioblastoma (T98G, U87MG) and glioma (KG1C) cell lines was one or two orders of magnitude higher than that in a human myelogenous leukemic cell line (HL-60), which showed higher sensitivity to H2O2. Pretreatment of these cell lines with L-buthionine-[S,R]-sulfoximine, which significantly reduced the intracellular GSH concentration, increased their sensitivity against H2O2, whereas pretreatment with N-acetyl-L-cysteine, which did not significantly change the intracellular GSH concentration, only marginally protected the cells from the cytotoxic effect of H2O2. The results suggest that drug sensitivity of tumor cells can be modified by glutathione-modulating compounds.

Acetylcysteine↗
PubMed1997

Prediction of in vivo drug metabolism in the human liver from in vitro metabolism data.

As a new approach to predicting in vivo drug metabolism in humans, scaling of in vivo metabolic clearance from in vitro data obtained using human liver microsomes or hepatocytes is described in this review, based on the large number of literature data. Successful predictions were obtained for verapamil, loxtidine (lavoltidine), diazepam, lidocaine, phenacetin and some other compounds where CLint,in vitro is comparable with CLint,in vivo. On the other hand, for some metabolic reactions, differences in CLint,in vitro and CLint,in vivo greater than 5-fold were observed. The following factors are considered to be the cause of the differences: (1) metabolism in tissues other than liver, (2) incorrect assumption of rapid equilibrium of drugs between blood and hepatocytes, (3) presence of active transport through the sinusoidal membrane, and (4) interindividual variability. Furthermore, the possibility of predicting in vivo drug metabolic clearance from results obtained using a recombinant system of human P450 isozyme was described for a model compound, YM796, where the predicted metabolic clearances obtained from the recombinant system, taking account of the content of the P450 isozyme CYP3A4 in the human microsomes, were comparable with the observed clearances using human liver microsomes containing different amounts of CYP3A4. Even in the case where the first-pass metabolism exhibits nonlinearity, it appears to be possible to predict in vivo metabolic clearance from in vitro metabolic data.

Biological Transport, Active↗
PubMed1997

The physiological effect of anti-GM1 antibodies on saltatory conduction and transmembrane currents in single motor axons.

Anti-ganglioside (anti-GM1) antibodies have been implicated in the pathogenesis of Guillain-Barré syndrome, multifocal motor neuropathy and motor neuron diseases. It has been held that they may interfere with saltatory conduction by blocking sodium channels. We tested this hypothesis by analysing action potentials from 140 single nerve fibres in 22 rat ventral roots using external longitudinal current measurement. High-titre anti-GM1 sera from Guillain-Barré syndrome or multifocal motor neuropathy patients, or anti-GM1 rabbit sera were applied to the rat ventral root, where saltatory conduction in single motor fibres was serially observed for 4-12 h (mean 8.2 h). For control experiments, we also tested anti-galactocerebroside (anti-GalC) sera, which causes acute demyelinative conduction block, and tetrodotoxin (TTX), a sodium channel blocker. Conduction block was found in 82% of the fibres treated with anti-GalC sera and 100% treated with TTX, but only in 2% (one out of 44) treated with the patients' sera and 5% (two out of 38) treated with rabbit anti-GM1 sera. All the nodes blocked by anti-GM1 sera revealed intense passive outward membrane current, in the internode just beyond the last active node. This pattern of current flow was similar to that in fibres blocked by demyelination with anti-GalC sera, and quite different from that seen in fibres blocked by reducing sodium currents with TTX. Our findings suggest that anti-GM1 sera neither mediate conduction block nor block sodium channels on their own. We conclude that physiological action of the antibody alone is insufficient to explain clinically observed conduction block in human diseases.

Action Potentials↗
PubMed1997

High-level expression of bovine beta-lactoglobulin in Pichia pastoris and characterization of its physical properties.

Bovine beta-lactoglobulin (BLG) variant A has been expressed in the methylotropic yeast Pichia pastoris by fusion of the cDNA to the sequence coding for the alpha-mating factor prepro-leader peptide from Saccharomyces cerevisiae. P. pastoris Mut+ transformants were obtained by single cross-over integration of the BLG-containing vector into the AOX1 locus. In a fed-batch fermenter, a cell density of approximately 300 mg/ml was achieved by controlled glycerol feeding for a total of 24 h. After 72 h of methanol induction, the secreted BLG reached levels of > 1 g/l. The secreted protein could be purified to homogeneity by ion-exchange chromatography. Amino-terminal sequencing of the secreted BLG revealed that the Glu-Ala spacer repeats inserted between the mature protein and the alpha-factor prepro-leader were still present. The purified protein was characterized by a number of methods, including CD spectroscopy, guanidine-HCl unfolding, crystallization and two-dimensional 1H-NMR spectroscopy. By all of these measures, the physical characteristics of recombinant BLG were indistinguishable from those of the native purified bovine BLG, making it useful as a model for protein folding and other biophysical studies.

Amino Acid Sequence↗
PubMed1997

Aggressive angiomyxoma of the scrotum.

Aggressive angiomyxoma is a rare benign tumor, arising in the pelvic soft tissues and perineum. It occurs almost exclusively in adult females. It is locally infiltrative and exhibiting a high risk of local recurrence. However, it is slow growing and does not metastatize. We report a case of aggressive angiomyxoma in an adult male which arose in the scrotum.

Genital Neoplasms, Male↗
PubMed1996

Prediction of in vivo drug disposition from in vitro data based on physiological pharmacokinetics.

Because of the increasing availability of human liver samples we now have a greater ability to predict in vivo drug disposition and pharmacokinetics in man from in vitro metabolic and binding studies. Firstly, we review several successful attempts to predict in vivo metabolic clearances in experimental animals and humans from in vitro biochemical parameters such as plasma protein binding and hepatic metabolism, based on anatomically and physiologically realistic pharmacokinetic models. Despite the success of this approach, however, there are still some difficulties in predicting in vivo hepatic metabolism in man using in vitro human liver samples due to the large inter-individual differences arising from polymorphism (intrinsic variability) or differences in enzyme activity (extrinsic variability) due to the conditions under which liver samples have been kept. We propose a possible method to overcome these errors resulting from inter-individual differences by applying the concept of a scaling factor. In the kinetic models used in prediction, we often make a number of assumptions, e.g. rapid equilibrium between the blood and hepatocytes, availability of only the unbound drug for uptake and elimination, and homogeneous distribution of enzymes along the path taken by the blood in the liver. However, recent evidence suggests that these assumptions are not necessarily valid. As examples involving the first and second assumptions, respectively, there is the plasma-membrane-permeability-limited metabolism of a high-clearance drug, 4-methylumbelliferone, and the albumin-mediated uptake of amphiphatic drugs. The multiple-indicator dilution method (MID) is useful for estimating the membrane permeability of drugs in liver perfusion systems where the spatial organization and cell polarity of the liver are maintained. If the aforementioned factors are taken into consideration and membrane permeabilities using human hepatocytes and/or subcellular fractions such as microsomes are measured under conditions close to those in vivo, much more reliable predictions of drug hepatic clearance in man may become possible.

Animals↗
PubMed1996

[Hypersensitivity pneumonitis monitored with serum KL-6, a marker of interstitial pneumonia].

A 44-year-old man was hospitalized because of exertional dyspnea that had progressed for one month. A chest X-ray film showed bilateral small nodular and reticular shadows. The patient presented with a positive inflammatory reaction and hypoxemia. Bronchoalveolar davage fluid had a high lymphocyte fraction and a low CD4/CD8 ratio. Trichosporon cutaneum antibodies were detected, and a specimen obtained by transbronchial lung biopsy showed alveolitis with granuloma formation. The patient reacted positively on a provocation test that was done by having him stay home for 5 days. Summer-type hypersensitivity pneumonitis was diagnosed, and a steroid was administered because of the prolonged abnormal chest roentgenographic findings. KL-6, a mucinous high-molecular-weight glycoprotein that is expressed on Type II pneumonocytes, was retrospectively used as a marker of pneumonitis. A new kit for enzyme-linked immunoassay (ED046) was used to measure the serum KL-6 level. The serum KL-6 level peaked approximately 10 days after the patient was admitted to the hospital and was thus kept away from antigens, and also after the provocation test. The steroid treatment was started, the KL-6 level decreased gradually. Within 2 months after steroid treatment began, the dose of the steroid was reduced and the KL-6 level decreased below the upper limit of normal. The KL-6 level remained low thereafter; it was not influenced by liver dysfunction or other inflammatory processes. However, the C-reactive protein level decreased rapidly after provocation and thereafter immediately returned to almost zero. The lactate dehydrogenose level peaked 8 days after provocation and decreased rapidly after steroid treatment. These results suggest that the serum KL-6 level provides new information regarding the clinical course and treatment of interstitial pneumonia. In addition KL-6 may be useful form monitoring disease activity, especially while tapering the dose of steroids in patients with interstitial pneumonia.

Adult↗