Biomedical subjects
T Hirokawa
Publications and source records attributed to T Hirokawa.
[The effects of fresh gas flow rate on the work of breathing during semi-closed circuit anesthesia].
To evaluate the effects of fresh gas flow rate on the work of breathing during semi-closed circuit anesthesia, we measured respiratory frequency, tidal volume, inspiratory work of breathing, peak inspiratory and expiratory flow rate and fluctuations in airway pressure during breathing with fresh gas flow of 6 l.min-1, 3 l.min-1 and 1.5 l.min-1. There was no significant difference among three flow rates in terms of tidal volume, respiratory frequency, inspiratory work of breathing, peak inspiratory flow rate and fluctuation in airway pressure at inspiration. On the other hand, in the expiratory phase, peak expiratory flow rate was lower and fluctuation in airway pressure at expiration was higher at 6 l.min-1 than those at 3 l.min-1 and 1.5 l.min-1, which may be indicative of increased expiratory work of breathing. The present study shows that low fresh gas flow rate does not increase the inspiratory work of breathing and high fresh gas flow rate may increase the expiratory work of breathing, implying that lowering the fresh gas flow is profitable for the work of breathing during semi-closed circuit anesthesia.
Simulated quantitative and qualitative isotachophoretic indices of 73 amino acids and peptides in the pH range 6.4-10.
Qualitative and quantitative isotachophoretic indices of 73 amino acids, dipeptides and tripeptides were simulated under 24 leading electrolyte conditions covering the pH range 6.4-10. The RE values and time-based zone lengths are tabulated together with the absolute mobility (m0) and pKa values used. The leading electrolyte used was 10 mM HCl and the pH buffers were imidazole, tris(hydroxymethylamino)methane, 2-amino-2-methyl-1,3-propanediol and ethanolamine. The simulated indices will be useful in the assessment of the separability and determination of the listed and related compounds.
Protein phosphatase type 2B (calcineurin)-mediated, FK506-sensitive regulation of intracellular ions in yeast is an important determinant for adaptation to high salt stress conditions.
To assess the physiological function of Ca(2+)-dependent protein phosphatase (PP2B) in the yeast Saccharomyces cerevisiae, the phenotypes of PP2B-deficient mutants were investigated. Although PP2B was dispensable for growth under normal conditions, the mutations did, however, cause growth inhibition under certain stress circumstances. The growth of the mutants was inhibited by NaCl and LiCl, but not by KCl, CaCl2, MgCl2 or nonspecific osmotic stresses. Upon shift to high NaCl medium, intracellular Na+ levels of both wild type yeast and the mutants initially increased at a comparable rate. However, internal Na+ in wild type cells started to decline more rapidly than the mutant cells during cultivation in high NaCl medium, indicating that PP2B is important in maintaining a gradient across the membrane. The protection against salt stress was achieved, at least in part, by the stimulation of Na+ export. The maintenance of a high level of internal K+ in high NaCl medium was also PP2B-dependent. In the presence of the immunosuppressant FK506, the growth behaviour and intracellular Na+ and K+ of wild type cells in high NaCl medium became very similar to those of the PP2B-deficient mutant in a manner dependent on the presence of the FK506 binding protein.
Solid-liquid transitions in argon clusters.
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Determination of limiting ionic mobilities and dissociation constants of some local anaesthetics.
The limiting ionic mobilities and thermodynamic acid dissociation constants were calculated from isotachophoretic experiments for the local anaesthetics procaine, tetracaine, lidocaine, trimecaine, bupivacaine, cinchocaine, diperodone, diocaine, cocaine, psicaine-neu, tropacocaine, amylocaine, beta-eucaine and leucinocaine. The pH values at which the local anaesthetics with very similar limiting ionic mobilities can be isotachophoretically separated were determined from simulated mobility curves. The measuring apparatus employed a high-frequency contactless conductivity detector.
Relative humidity, not absolute humidity, is of great importance when using a humidifier with a heating wire.
OBJECTIVES: Since the introduction of a humidifier with a heating wire, we have frequently experienced severe upper airway obstruction from consolidation of secretions, previously unencountered when a humidifier without a heating wire was used. Such problems led to the suspicion that the heating wire incorporated into the breathing circuit of the heated humidifier might be the cause. Therefore, we scheduled an experiment to assess the hypothesis that relative humidity, rather than absolute humidity, is a dominant factor in the case of drying secretions in the upper airway when using such a humidifier. DESIGN: Three clinical case reports and an experiment with a tracheal model. SETTING: Intensive care units at Saitama Medical Center, Saitama Medical School, Saitama, Japan. PATIENTS: Three intubated patients. MEASUREMENTS AND MAIN RESULTS: An experiment with a tracheal model showed that gas with a higher temperature and lower relative humidity (35 degrees C, 48%) deprived the tracheal model of significantly more water (5.9 +/- 0.2 [SD] g) than gas with a lower temperature and higher relative humidity (24 degrees C, 87%) (2.9 +/- 0.4 g; p less than .01), even though the gases contained the same amount of water vapor (19 mg H2O/L) minus the same absolute humidity. CONCLUSIONS: A heated humidifier with a heating wire incorporated into the breathing circuit may be dangerous when only temperature is monitored and controlled. Relative humidity, rather than absolute humidity, is a dominant factor in the case of drying secretions in the upper airway when using such a humidifier.
Electrophoretic mobility and dissociation constants of tripeptides evaluated by isotachophoresis.
Ionic mobilities and dissociation constants of twenty peptides (seventeen tripeptides and a few oligoglycines) were evaluated on the basis of the observed isotachophoretic qualitative indices RE in the pH range 8.1-9.5 by the use of a least-squares method. Good correlation was obtained among the mobilities of amino acids, dipeptides and tripeptides when the clay ball model and the conventional formula weight were adopted.
Isotachophoretic determination of mobility and pKa by means of computer simulation. V. Evaluation of mo and pKa of twenty-eight dipeptides and assessment of separability.
Isotachophoretic qualitative indices, RE, for twenty-eight dipeptides were measured in the range pH 7.4-9.6. The absolute mobility, mo, and pKa values were evaluated by the use of the least-squares method, utilizing a simulation of the isotachophoretic steady state. The mo values were newly evaluated and the pKa values were in good agreement with literature values. By comparison of the evaluated mo and pKa values of the dipeptides with those of the constituent amino acids, simple relationships were found which may be used to estimate the mo and pKa values of other dipeptides. The separability of the dipeptides was also evaluated by considering the differences between their simulated effective mobilities. It is concluded that isotachophoresis is very convenient for the separation of dipeptides and their constituent amino acids.
Isotachophoretic determination of mobility and pKa by means of computer simulation. IV. Evaluation of m0 and pKa of twenty-six amino acids and assessment of the separability.
Isotachophoretic qualitative indices, RE, of twenty-six amino acids were measured at several pHL values in the range of 8.6-9.6. The absolute mobility, m0, and pKa values were evaluated by the use of a least-squares method utilizing a simulation of the isotachophoretic steady state. The pKa values were in good agreement with values cited in the literature. The RE values simulated using the evaluated constants were in good agreement with RE values converted from step heights observed previously. By comparing the previously observed separation behaviour of amino acids with their simulated effective mobilities, it is concluded that when the effective mobility of samples differs by ca. 1 X 10(-5) cm2 V-1 s-1 at the steady state, ca. 10-nmol samples can be separated by the use of a 80 cm X 0.5 mm I.D. tube. The simulated effective mobilities of twenty-two amino acids were tabulated to assess the separability under some typical electrolyte conditions.
[Phase II study of UFT for head and neck cancer].
A Phase II study of UFT for head and neck cancer was conducted in 10 institutions. UFT is a mixture of Futraful and uracil. Eighty-four patients entered this trial, of which 60 were evaluable. UFT was administered orally at a daily dose of 600 mg/day. Eight patients achieved complete response and 10 achieved partial response with an over-all response rate of 30.0 %. Evaluating response according to by histology, the response rate was 30.9% for cases of squamous cell carcinoma. Complete response was observed in one case of undifferentiated carcinoma. Response rate according to primary site was 33 to 40% for the nose & paranasal sinuses, mesopharynx, hypopharynx and larynx. The response rate was 28.9% for the group of patients treated previously, and 33.3% for the group previously untreated. The mean time for 50% or more regression of the tumor was 4.3 weeks. Toxic effects appeared in 40.3% of 67 evaluable cases as anorexia, nausea, vomiting, stomatitis, diarrhea etc. In one case of maxillary carcinoma, severe bone marrow suppression was observed. We concluded that UFT therapy was markedly effective for head and neck cancer.
Analytical isotachophoresis utilizing computer simulation. II. Assessment of optimum separation conditions for urinary trifluoroacetic acid metabolized from anaesthetic halothane.
Experimentally determined optimum separation conditions for a metabolite of anaesthetic halothane in urine, trifluoroacetic acid, were assessed by means of computer simulation of the isotachophoretic steady-state. The simulation confirmed that urinary acids and trifluoroacetic acid can be separated in the limited pH range of 3.5-3.7 buffered by beta-alanine, as far as the pH dependence of effective mobility is utilized. The separated fraction of the trifluoroacetic acid zone was identified by mass spectrometry. The simulated coefficient of the calibration curve agreed well with the observed value.
[Experimental chemotherapy using a transplanted head and neck cancer model in athymic nude mice].
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Intraarterial infusion of 4'-O-tetrahydropyranyl-adriamycin for head and neck tumors.
THP-adriamycin was administered in a dose of 5 to 20 mg, 3 times a week, and the results showed 4 cases of CR, 5 cases of PR, 3 cases of MR and 2 cases of NC with the accumulated total dose of less than 100 mg. Histological effects were slight in a total dose of less than 50 mg, while the effects appeared in a total dose of 60 to 70 mg and further effects were obtained after about 1 week of the termination of the therapy. Leukopenia occurred in 6 of 14 cases. The side effects of THP-adriamycin were milder than those of ADM.
[THP-adriamycin in head and neck tumor].
Primary effects and side-effects of a new anthracycline antineoplastic agent, THP-adriamycin (THP-ADM), were examined in 20 patients with malignant head and neck tumors. According to a classification by tumor sites, there were 6 cases of oropharynx, 6 of nose and sinuses, 3 of tongue, 2 of floor of mouth, 2 of neck and 1 of external auditory meatus. According to the tissue classification, there were 11 cases of squamous cell ca., 6 cases of malignant lymphoma, each one case of anaplastic ca., carcino sarcoma and adeno cystic ca. There were 16 previously untreated cases and 4 pretreated cases. Twelve cases received THP-ADM by intraarterial injection and 8 cases by the same dose. 10 to 20 mg/body 3 times a week, in a total of 40 to 100 mg. 2 CR, 5 PR, 3 MR and 4 NC in 14 cases with carcinoma, and 2 CR, 3 PR and 1 MR in 6 cases with malignant lymphoma were obtained. Among 12 cases receiving intraarterial injection, 3 CR and 5 PR were obtained. The decrease of WBC counts below 3000/mm3 after THP-ADM administration was observed in 9 cases. Side effect of THP-ADM appeared to be less severe than that of Adriamycin.
[Moderate dose methotrexate with citrovorum factor rescue therapy in the treatment of head and neck cancer].
A clinical trial of moderate dose methotrexate (MTX)-CF rescue was conducted in 12 institutions. Thirty-seven patients with head and neck carcinoma entered this trial, of which 32 were evaluable. MTX was administered 350 mg/m2 (500 mg/body) by i.v. drip over 6 hours. Three hours after completion of MTX infusion, CF rescue was started. There was no complete response in 32 patients. Nine patients showed partial response with the response rate of 28%. The response rates were 21% for the group of patients treated previously, and 75% for the group untreated previously. MTX concentration in plasma was determined at 6, 24, 48 and 72 hours after the initiation of MTX infusion, and the assay results revealed a safe range. GI disturbances were seen at the rates of 11 to 38%. Bone marrow suppression was mild and no renal toxicity was observed. We concluded that the moderate dose MTX-CF rescue therapy was useful for head and neck carcinoma. As a next step, we are planning to conduct a clinical trial of high-dose MTX.
[Clinical results of FAR (5-FU, vitamin A, and radiation) therapy in head and neck cancer].
Combination therapy of 5-FU, vitamin A and radiation (FAR therapy) was given to 50 patients with squamous cell carcinoma of the head and neck. The primary effect was observed in 22 patients who received FAR therapy as radical therapy. Among them, only 4 patients had recurrence or metastasis, and death was none. FAR therapy was given to 4 patients as pre-operative therapy and to 2 patients as post-operative therapy. However, the number of cases was not enough for us to draw any conclusion. In the group of 22 patients consisting of patients with recurrence or metastasis and patients who refused operation or were unresectable, no primary effect was observed only in 4 patients. Among a total of 50 patients, only 4 patients did not show a primary response to FAR therapy, 19 had relapse, 19 died (6 cases of them died from other causes), and 31 are still alive. There were no patients having severe side effects. From these results, FAR therapy seemed to be worth trying in treatment of head and neck cancer.
[Correlation between induced abortion and abortion and premature delivery].
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