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Biomedical subjects

K Asami

Publications and source records attributed to K Asami.

At least 73 records · Page 4Linked to original sources
PubMed1996

Earlier activation of the distal than the proximal site of the coronary sinus may represent retrograde conduction through AV node: significance of recording of far distal coronary sinus.

During retrograde conduction through an accessory pathway (AP) or the atrioventricular (AV) node, earlier activation of the distal recording site than a more proximal site of the coronary sinus (CS) generally indicates retrograde conduction via a distally located AP. Thus, after successful ablation of a left-sided AP, if the distal CS recording site is activated earlier than a more proximal site retrogradely, it is considered to suggest-in the absence of His-bundle recording or more frequently in the setting of poor recording of the low septal right atrial electrogram-a conduction via a second AP (located more distally), and not conduction via the AV node. Yet, we hypothesized that retrograde conduction through the AV node may activate the far distal site of the CS (CSD) earlier than a more proximal site, as the anterior atrial wavefront, coming retrogradely from the AV node and traveling along the anterior mitral annulus, could reach the CSD earlier than a more proximal site. To test this we studied 18 patients with intact retrograde conduction via the AV node, but without evidence of an AP. The CSD was recorded by means of a quadripolar catheter (interelectrode distance of 2-5 mm); retrograde activation sequence at the distal (CSD1-2) versus proximal (CSD3-4) bipolar recording site was determined during ventricular stimulation. In 12 of 18 patients the CSD1-2 recording site was activated 5-10 ms earlier than the CSD3-4 recording site, in 3 of 18 patients the CSD1-2 site was activated 5 ms later than the CSD3-4 site; in the remaining 3 patients both recording sites were depolarized simultaneously. The results indicate that the CSD was often depolarized earlier than a more proximal site by impulses that conducted to the atria retrogradely via the AV node while the quadripolar recording catheter was placed at the CSD. This observation, although not well documented previously, suggests that the sequence of retrograde atrial activation in the CS should be studied carefully in consideration of the actual location of the mapping catheter in order to correctly diagnose the presence or absence of conduction via an AP.

Adolescent↗
PubMed1995

Dielectric behavior of non-spherical cells in culture.

In order to study dielectric behavior of non-spherical cells growing in suspension culture, a dielectric theory has been developed based on the shell-ellipsoid model that is a conducting ellipsoid covered with a thin insulating shell. The theory predicts three dielectric relaxations for a suspension of ellipsoidal cells with three different semiaxes. For prolate spheroidal cells with two different semiaxes that show two dielectric relaxations the effect of the axial ratio on the dielectric relaxations was examined in detail. The low-frequency relaxation attributed to the component along the major axis strongly depends on the axial ratio, while the high-frequency relaxation due to the component along the minor axis is rather insensitive to the axial ratio. The theory is also applicable to simulation of dielectric behavior of yeast cells in synchronized and asynchronized culture by assuming that budding yeast cells are prolate spheroids.

Cell Division↗
PubMed1995

Dielectric analysis of yeast cell growth.

On-line dielectric measurements of yeast cells (Saccharomyces cerevisiae) growing in suspension culture were made over a frequency range from 0.1 to 100 MHz. The amplitude of the dielectric dispersion centered at about 1 MHz increased exponentially with cultivation time in the logarithmic growth phase and then remained constant in the stationary phase. This result clearly indicates that the mass and concentration of the yeasts can be monitored by the dielectric method. In the late logarithmic growth phase, a subdispersion appeared around 10 MHz, whose amplitude was less than 6% of that of the whole dispersion. The development of the subdispersion indicates the increase in the volume of the vacuole in the yeasts. In synchronized cell culture, the amplitude of the dispersion changed stepwise. The time interval between the steps was about 100 min. that corresponds to the generation time of the yeast.

Cell Cycle↗
PubMed1995

Successful treatment of retinoic acid syndrome with high-dose dexamethasone pulse therapy in a child with acute promyelocytic leukemia treated with ATRA.

A 5 year old female developed femoral pain, fever, and hemorrhagic tendency. She was diagnosed as having acute promyelocytic leukemia (APL). Approximately 2 weeks after the administration of all-trans retinoic acid (ATRA), she developed a high fever, edema, and respiratory distress which met the criteria for retinoic acid syndrome. At first, we tried to treat the patient with oral corticosteroid, however, this approach was unsuccessful. Considering the worsening of her condition, we then chose to administer a large dose of intravenous dexamethasone therapy for 3 days. Immediately after this therapy, she became afebrile, respiratory distress and edema disappeared, and there was a general improvement of the symptoms. All-trans retinoic acid at the reduced dose of 25 mg/m2, was continued for an additional 6 weeks and then discontinued. Since the cessation of dexamethasone and ATRA, there has been no relapse of APL in this patient. Although based on only one case, we recommend the intravenous high-dose dexamethasone pulse therapy (13 mg/m2 per day, for 3 days) for treating retinoic acid syndrome which develops in pediatric APL patients treated with ATRA.

Child, Preschool↗
PubMed1995

Screening for neuroblastoma: a 9-year birth cohort-based study in Niigata, Japan.

Between April 1985 and March 1994 (9 years), 229,346 babies were born in Niigata prefecture, and 201,888 (88.0%) underwent mass screening (MS) for neuroblastoma at 6 months of age. To date, 29 infants have been screen-detected as having neuroblastoma (1:7908). All screen-detected patients survived after removal of the primary tumor. In the same birth cohort, 17 additional children were clinically diagnosed as having neuroblastoma. The cumulative incidence rate of neuroblastoma at 5 years of age was 10.5 per 100,000 live births in the 5-year birth cohort before MS was introduced, and 18.6 per 100,000 in the first 5-year birth cohort after MS was introduced. These values were not statistically different. The birth cohort incidence rate increased significantly to 22.2 per 100,000 (p < 5% compared with before MS) after the method of MS was changed to high-power liquid chromatography (HPLC), even though this latest birth cohort has not been followed for 5 years. The population-based mortality rate from neuroblastoma was 5.9 per 100,000 in the 5-year birth cohort before MS, and 4.5 per 100,000 after MS in the first 5-year birth cohort, using the vanillymandelic acid (VMA) spot test. These values were not statistically significant. In contrast, no death was observed in the next 4-year birth cohort after MS using HPLC; however, this birth cohort has not yet been followed for 5 years.

Chi-Square Distribution↗
PubMed1995

Fungal metabolites. XVIII. New membrane-modifying peptides, trichorozins I-IV, from the fungus Trichoderma harzianum.

New membrane-modifying peptides, trichorozins I-IV, have been isolated from conidia of the fungus Trichoderma harzianum. Their amino acid sequences were clearly determined by spectrometric methods and, furthermore, they were synthesized by the solution-phase method. Trichorozins are a family of the class of peptaibols and are composed of 11 residues including an amino alcohol. Trichorozins exhibited voltage-dependent ion channel-like activity in lipid bilayers.

Amino Acid Sequence↗
PubMed1995

Effect of carbon dioxide on facial nerve blood flow in rabbits.

We investigated blood flow to the facial nerve, cerebral cortex, brain stem, and dura mater in 16 white rabbits using a nonradioactive microsphere technique at various levels of arterial carbon dioxide tension. The blood flow to the facial nerve in the 32 temporal bones was 59.1 +/- 32.9 microliters/g/min. Unlike cerebral blood flow, blood flow to the facial nerve and dura mater did not show any marked increase upon carbon dioxide inhalation.

Administration, Inhalation↗
PubMed1994

Membrane admittance of cloned muscle cells in culture: use of a micropipet technique.

The impedance characteristics of muscle cells have been investigated by many investigators because of its unique features. The studies of the electrical properties of cloned cultured muscle cells, however, are scant and only a handful of papers have been published. In this report, the admittance of cultured Myoblast L6 cells was investigated. The capacitance and conductance of mononucleate myoblast cell membrane were found to be 2.2-2.5 microF/cm2 and 50-60 microS/cm2 and independent of frequency. The capacitance of 2.2 microF/cm2 is larger than the widely accepted capacitance value for most of the biological cell membranes, i.e., 1 microF/cm2. In contrast, those found for fused multinucleate myotubes are 5-6 microF/cm2 and 0.4 mS/cm2 and exhibited a marked frequency dependence. We postulate that the large and frequency dependent capacitance of myotubes does not arise from the surface membrane alone but is due to a tubule-like structure which may be similar to those found in frog muscles. Analysis of the results using an equivalent circuit demonstrates that the capacitance of myotubes is independent of frequency when the correction is made for the series resistances which are distributed in the lumen of tubule-like structure. An alternative explanation for the frequency dependent capacitance is based on the use of the transmission line theory or cable equation. The cable theory predicts that measured capacitance and conductance are inherently a function of frequency regardless of the nature of membrane capacitance and conductance if the dimension of cells is larger than or comparable to the propagation constant.

Animals↗
PubMed1994

Assessment of testicular biopsy after cessation of maintenance chemotherapy in childhood acute lymphoblastic leukemia: a report from the Children's Cancer and Leukemia Study Group.

Among 484 male patients with acute lymphoblastic leukemia (ALL) registered into the protocols CCLSG 811, 841 and 874, from 1981 through 1990, 246 patients completed their protocols and were in continuous complete remission (CCR) for more than 3 years. One hundred and seven patients received bilateral testicular biopsies at the time of cessation of maintenance chemotherapy. Eight patients (7.5%) were found to have occult testicular leukemia (TL). Three of them did not receive any additional therapy and all suffered subsequent relapses; one bone marrow relapse and two testicular relapses. The other 3 patients received testicular radiation combined with an additional 2 years of chemotherapy, resulting in CCR for more than 6 years 10 months, 7 years 6 months, and 8 years 6 months. One with chemotherapy alone and another with radiation alone showed subsequent relapse. Overt TL after negative initial biopsy was developed in 3 (3.0%) of the 99 patients. All of them received testicular radiation with chemotherapy, resulting again in CCR for more than 1 year 0 months and 5 years 3 months; one patient showed relapse in testes and bone marrow after 3 years 8 months of CCR. These studies suggested that occult TL has an adverse prognostic significance unless retrieval chemotherapy is given and that performance of testicular biopsy at completion of maintenance chemotherapy is not contributory to prolongation of disease-free survival for males with ALL because the treatment employing testicular radiation plus retrieval chemotherapy for both occult TL and isolated overt TL after off-therapy is similarly very effective.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Measurement of beta 2-glycoprotein I (apolipoprotein H)-independent anticardiolipin antibody in human immunodeficiency virus-1-positive and -negative hemophiliacs.

The authors studied whether or not anticardiolipin antibody (aCL), which is frequently detected in hemophiliacs with human immunodeficiency virus-1 (HIV-1) infection, is dependent on beta 2-glycoprotein I (GPI), a cofactor of cardiolipin (CL). GPI-independent aCL was positive in 27 of 36 hemophiliacs with HIV-1 antibody (75%) and in 23 of 29 patients without HIV-1 antibody (79%). However, only six HIV-1-positive and four HIV-1-negative patients were positive for GPI-dependent aCL. Thus the aCL in these hemophiliacs was GPI independent and therefore different from the aCL found in autoimmune diseases, such as systemic lupus erythematosus.

Antibodies, Anticardiolipin↗
PubMed1993

Anticoagulant activity of an anti-beta 2-glycoprotein I antibody is dependent on the presence of beta 2-glycoprotein I.

We studied whether or not an anti-beta 2-glycoprotein I antibody (aGPI) had lupus anticoagulant-like activity, employing the diluted Russel viper venom time (dRVVT) and kaolin clotting time (KCT) as indices. aGPI prolonged the dRVVT and KCT of beta 2-glycoprotein I (GPI)-depleted normal plasma in the presence of extrinsic GPI. This prolongation of the dRVVT and KCT occurred immediately after the addition of aGPI and GPI, and was subsequently enhanced further in a time-dependent manner. The GPI/aGPI combination was judged to have lupus anticoagulant-like activity by the dRVVT-platelet neutralization test, but this was not confirmed by a lupus anticoagulant-specific test, i.e., the activated partial prothrombin time (APTT) using hexagonal phospholipid. From these findings, it can be concluded that aGPI has lupus anticoagulant-like activity in the presence of GPI, but may be a partially or considerably different antiphospholipid antibody from lupus anticoagulant. Further investigations may be needed to clarify this point.

Antibodies↗
PubMed1993

Calculation and measurement of the dipole moment of small proteins: use of protein data base.

The dipole moments of small protein molecules were determined experimentally in order to validate the calculated dipole moments by previous investigators. We found that the agreements are satisfactory for some proteins. There are, however, many proteins for which the agreement is less than satisfactory. In order to find the cause of the disagreement, the dipole moments of these proteins were recalculated using the Brookhaven Protein Data Bank. We calculated the dipole moment due to fixed surface charges and the bond moments of all the carbonyl groups in main chain and side chains. The calculation consists of the mean moments and their mean square fluctuations. In addition, we investigated the effect of electrostatic interactions between charged sites for several proteins. These results show that incorporation of the interactions does not affect substantially the calculated dipole moments. The rms fluctuation of the dipole moment is found to be small but not negligible. In conclusion, recalculated dipole moments are in good agreement with the observed values.

Biophysics↗
PubMed1993

[Results of the CCLSG high risk ALL 874 protocol in childhood acute lymphoblastic leukemia. Children's Cancer and Leukemia Study Group].

One hundred and eighty eight children with acute lymphoblastic leukemia (ALL) were treated in a Children's Cancer and Leukemia Study Group high-risk ALL 874 study from April, 1987 to September, 1991. These patients received a four-drug induction regimen followed by the early consolidation regimen, cranial irradiation at 6 months of remission and three years of continuation therapy with rotational administration of four drugs. The patients were randomized into two regimens. In regimen A, the consolidation chemotherapy consisted of the intermediate dose cytosine arabinoside (Ara-C), cyclophosphamide (CPM) plus 6MP, and in regimen B, it consisted of high-dose Ara-C plus CPM. Regimen A was given to 106 patients and 82 patients received regimen B. The complete remission induction rate for regimen A and B was 89.4% (93/104) and 98.7% (78/79), respectively. The 3-year event-free-survival (EFS) rate was 70.6% for regimen A, which was higher than the 56.7% for regimen B. The 3-year EFS rate was 44.4% for the 53 patients with an initial leukocyte count > or = 10 x 10(4)/microliters and 72.2% for 132 patients with a leukocyte count < 10 x 10(4)/microliter. We considered that Ara-C plus L-asp, added to the conventional high-risk ALL 811 protocol, improved the prognosis of the high risk ALL patients. However, further intensive chemotherapy was required for improvement of the outcome of the patients with hyperleukocytosis (> or = 10 x 10(4)/microliters).

Adolescent↗