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Biomedical subjects

A Iwata

Publications and source records attributed to A Iwata.

At least 19 recordsLinked to original sources
PubMed1992

Sequence determination of cDNA clones of transcripts from the tumor-associated region of the Marek's disease virus genome.

The number of 132-bp tandem direct repeats within the long inverted repeat region of the Marek's disease virus type 1 (MDV1) genome increases concomitantly with the loss of oncogenicity during serial passages in cultured cells. Twelve clones carrying the 132-bp sequence were isolated from a cDNA library constructed from chicken embryo fibroblasts infected with the MDV1 Md5 strain. Through sequence analysis of a cDNA clone and primer extension analysis, the corresponding mRNA was found to be a linear transcript which included the two 132-bp tandem direct repeats. Two open reading frames were found in this transcript. One had a week homology with v-fms. The other should increase its size concomitantly with expansion of the 132-bp tandem direct repeat. PCR analysis of both cDNA clones and RNA gave amplified products which were as large as that produced from the genomic clone, indicating that a majority of mRNA from this region is composed of unspliced transcripts.

Amino Acid Sequence↗
PubMed1992

The complete sequence of African horsesickness virus serotype 4 (vaccine strain) RNA segment 5 and its predicted polypeptide compared with NS1 of bluetongue virus.

The complete sequence of RNA segment 5 of the African horsesickness virus serotype 4 (AHSV-4) vaccine strain was determined from cDNA clones inserted into pBR322. The RNA is 1751 bp long (M(r) 1.12 x 10(6)) and contains an open reading frame encoding a protein of 548 amino acids (M(r) 63,122) with a net charge of +0.5 at neutral pH. A comparison of the sequence of AHSV-4 segment 5 with that of segment 6 of bluetongue virus (BTV) serotypes 10 and 17 revealed 49.2% and 48.9% nucleotide similarity, respectively, and 31.4% amino acid similarity. However, AHSV-4 segment 5 has no significant similarity to BTV segment 5. In addition, Northern blot hybridization showed that full-length AHSV-4 segment 5 cDNA cross-hybridized with the corresponding genes of all serotypes of attenuated AHSV.

African Horse Sickness Virus↗
PubMed1992

[Development of a new method for calibration of pneumotachograph according to flow rate--evaluation of a computer-controlled-system for assessing respiratory gas exchange using this method].

1) We evaluated the method for calibrating the pneumotachograph according to flow rate by the software on personal computer. Flow volume was detected using the approximated equation (y = 1.294x2 + 0.989x + 35.824, r = 0.976, p less than 0.01) from various mean flow rate and integration of output voltage. The error between syringe volume (21) and the estimated value on the equation was 10 +/- 8 ml (0.48 +/- 0.42%). 2) Using the method described in 1), we developed computer-controlled-system for assessing respiratory gas exchange by mixing chamber method. To evaluate the accuracy of the system as compared with the Douglas Bag method, we measured the gas parameters of the both methods for two male subjects at rest(3 and 5min) and steady state exercise (3 min., 60-240watt). The error between the both methods were within +/- 5% in ventilation(VE), mixed expired O2 (FEO2) and CO2 (FECO2) concentration, and were within +/- 8% in O2 uptake(VO2) and CO2 production (VCO2). There were high positive correlation (r greater than 0.99, p less than 0.01) between the both methods in the all parameters. These results indicate that the system in this study would be practical use, that VE can be measured in only one pneumotachograph, even if the range of flow rate was wide(e.g. from rest to heavy exercise).

Adult↗
PubMed1992

A study of the effects of manidipine on the diurnal variation of arterial pressure and hemodynamics in patients with essential hypertension.

In order to investigate the effects of manidipine, a newly developed long-acting calcium antagonist, on the diurnal variation of arterial pressure and systemic hemodynamics in patients with essential hypertension, we examined 24-h arterial pressure using a direct arterial pressure monitoring method and cardiac output using the cuvette method before and during manidipine treatment. Once-a-day administration of manidipine at daily doses of 10 to 40 mg decreased systolic and diastolic arterial pressures at almost all measurement points. The arterial pressure reductions were not significantly different between daytime and nighttime. Arterial pressure variability expressed in terms of the standard deviation of values was not affected by manidipine treatment. Thus, it appears that patients treated with manidipine can avoid the excessive decrease in arterial pressure during nighttime that may occur with the use of some other calcium antagonists. Heart rate and its variability were unaffected by manidipine treatment. A hemodynamic study revealed that manidipine did not change cardiac output, but significantly decreased total peripheral vascular resistance at rest. It is concluded that once-a-day administration of manidipine at daily doses of 10 to 40 mg brings about a safe and stable antihypertensive effect over a 24-h period, without affecting the diurnal variation of arterial pressure and heart rate. Dilation of the resistance vessels underlies the antihypertensive effect of the agent.

Adult↗
PubMed1991

The first milliseconds of the pore formed by a fusogenic viral envelope protein during membrane fusion.

Fibroblasts expressing the influenza virus hemagglutinin on their plasma membrane were patch clamped while they fused to erythrocytes. An increase in the fibroblast's membrane capacitance indicated the opening of the "fusion pore," the first aqueous connection between the fusing cells. We show here that the capacitance increase is preceded by a brief current transient, generated as the erythrocyte discharges its membrane potential through the nascent fusion pore. This signal allows one to calculate the pore conductance during the first milliseconds of its existence. The pore conductance jumps from 0 to approximately 150 pS and then grows more gradually over the subsequent tens of milliseconds until growth is arrested. The initial conductance is similar to that of a large ion channel and suggests that the pore is initially only 1-2 nm wide. Hence, we are probably observing events caused by only a small number of hemagglutinin molecules.

Animals↗
PubMed1991

[Study on the limitation for detecting anaerobic threshold by respiratory frequency].

It has been reported that respiratory frequency (F) serves to determine anaerobic threshold (AT). The purpose of this study was to investigate whether the method detecting AT by using F is influenced by the subject's condition such as the existence of sport experiences. Ten healthy adults volunteered to perform progressive cycle ergometer exercise with workloads increased by 30-W (female:20-W) every 2 min at 60 rpm. VO2 at AT were determined by four different methods, which detect the point of 1)nonlinear increase in VE, VCO2, and increase in VE/VO2 without increasing in VE/VCO2 (AT-v), 2) nonlinear increase in F (visual estimation: AT-VF), 3) inflection in F by multisegment linear regression (AT-CF), 4) inflection with omitting above RC point as with 3) (AT-CF2). The mean VO2 at AT-VF (40.8 +/- 9.2 ml/kg/min) and AT-CF (42.7 +/- 9.9 ml/kg/min) was significantly higher compared with AT-V (28.2 +/- 10.4 ml/kg/min) and not RC (42.3 +/- 10.0 ml/kg/min). It would be possible that AT-VF and AT-CF indicated RC, but not AT. There were no significant differences between AT-CF2 (28.2 +/- 10.9 ml/kg/min) and AT-V, and a highly positive correlation (r = 0.79, p less than 0.05) was observed between them. It was recognized that F reached a plateau at AT in four of the subjects. The error between AT-V and AT-CF2 was observed individual variations and the error between them within 5% was observed in only one subject. These results suggest that F is inadequate as an indicator of the AT, because F may be influenced by entrainment of breathing and pedalling frequency.

Adult↗
PubMed1991

Individual custom-designed modelling for the finite element method to be used in the forward calculation of a body surface isopotential map.

Body surface potential maps differ considerably in their pattern even among normals, depending upon torso configuration. Thus individualized modelling of the heart-torso model is certainly desirable for a forward problem if it can be achieved without much effort. In this paper such a heart-torso model which is flexible enough to adapt to different body shapes with ease will be reported. As its basic structure, the innermost sphere represents the electromotive force of the heart, the outermost ellipsoid surface representing the torso surface and nine similar ellipsoid surfaces intervening between the two with step-wise increasing diameters were considered. We made 98 radiating penetration points for the innermost sphere as well as the 10 intervening ellipsoid surfaces. By making use of neighboring points of penetration as corners, the heart-torso model was divided into 4992 tetrahedral elements for a finite element method calculation. Once this basic structure was established, it was found to be very easy to be modified in a computer in order to make it fit to individual torso configurations quite faithfully by deforming the outermost ellipsoid. Individualized torso-heart models were built and their maps were simulated using data obtained from several healthy subjects. This paper discusses the results of two individuals, one muscular and the other slender, who exhibited considerably different body surface potential maps.

Adult↗
PubMed1990

Application of the Karhunen-Loeve expansion to evaluate regional cardiac excitation in body surface potential maps.

The authors investigated the usefulness of the Karhunen-Loeve technique applied to body surface maps to study regional cardiac excitation. Eigenvectors were derived from the body surface potential maps of 120 healthy adults using the Karhunen-Loeve expansion theory. Then, in the maps of various types of ventricular hypertrophy, each eigenvector coefficient was calculated for a statistical comparison. The first eigenvector coefficient in early QRS and the second in mid QRS were larger in patients with asymmetrical septal hypertrophy and in patients with left ventricular hypertrophy, respectively. The third was larger in patients with right ventricular hypertrophy. In the maps of patients with previous anteroseptal myocardial infarction, the second eigenvector coefficient decreased with asynergy of the anterior to apical wall, and the first decreased with the asynergy of the interventricular septum. They conclude that some eigenvector components and coefficients at particular times in the QRS are sensitive to changes in regional cardiac excitation and that they may facilitate the detection of local excitation changes such as occur in hypertrophy or infarction.

Adult↗
PubMed1990

[The pharmacokinetics of pranoprofen in humans].

The pharmacokinetics of pranoprofen, 2-(5H-[1]benzopyrano[2,3-b]pyridin-7-yl) propionic acid (I) in humans were examined. 1-O-Acylglucuronide of I (II) and its isomer (III) were isolated from the human urine after oral administration of I. The stability of II was tested in order to establish the suitable conditions for the storage and handling of biological samples. Maximum stability of II was found at pH 3-4. Unchanged drugs, II and III were detected in the human plasma after oral administration of I. Plasma concentrations of these compounds reached the maximum at 1-2 h after the administration and thereafter decreased biphasically. From the urinary sample, 1-O-acylglucoside of I (IV) was detected in addition to unchanged drugs, II and III. Within 24 h after dosing, 1.3, 84.0, 7.0 and 0.6% of the dose were excreted as I, II, III and IV, respectively and the total urinary excretion amounted to 92.9% in term of unchanged drug.

Administration, Oral↗
PubMed1990

[Results of pulmonary resections in elderly patients with primary lung cancer].

Forty-one patients over the age of 70 years, who had been operated upon for a primary lung cancer during 13 years until August, 1988, were reviewed. There were 32 males and 9 females, among whom the oldest was an 85-year-old male. These patients composed of 28.7% of the patients who had undergone a resectional lung surgery due to a primary lung cancer during the same period of time. These included 26 patients of stage I, 11 of IIIA, 3 of IIIB and 2 of IV. Twenty-two of them were with a squamous cell carcinoma, 18 with an adenocarcinoma, and one with a small cell carcinoma. Thirty-two patients underwent a lobectomy, including two undergoing a sleeve lobectomy. Three patients underwent a left pneumonectomy, and seven underwent a segmentectomy or a wedge resection. A combined chest wall resection was done in 5 of them. One patient underwent the second surgery for a metastasis to the contralateral lung following a left pneumonectomy. Our safety criteria of pulmonary functions for surgery were as follows; a predicted postoperative %VC greater than 40% for any type of pulmonary resection, a preoperative FEV1.0 greater than 1,000 ml for lobectomy and that greater than 1,300 ml for left pneumonectomy. These criteria were identical to those for patients younger than 70 years of age. But some patients even with respiratory functions slightly less than these lower limits did tolerate lobectomies or pneumonectomies. The latter patients, however, cleared what we call "one-flight test" as well as the other patients did.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1989

Patch clamp studies of single cell-fusion events mediated by a viral fusion protein.

To enter cells, viruses must fuse their envelope with a host cell membrane. Fusion is mediated by specific, membrane-spanning fusion proteins, of which the influenza virus haemagglutinins (HA) are the best characterized. Several HAs have been sequenced, and the crystal structure of the major part of one HA is known. The conditions for fusion and some of the rearrangements in the HA that accompany fusion are well understood, but it remains unclear how HA causes bilayers to fuse. We have observed, in real time, unitary cell-fusion events caused by HA. Fibroblasts expressing HA were induced to fuse with red blood cells by a rapid drop in pH. Fusion was monitored by fluorescence microscopy, and by measuring the membrane conductance and capacitance of the fibroblast. The earliest event observed was the sudden opening of an aqueous pore connecting the cytoplasms of the fusing cells. Initially, the pore conductance often fluctuated between zero and approximately 600 pS, as if the pore were opening and closing repeatedly. Later, it increased over tens of seconds, as if the pore dilated. We suggest that, as in exocytosis, HA-mediated membrane fusion begins with the formation of a narrow pore. Based on the conductance, we estimate the initial diameter of the pore to be no more than twice that of a gap junction channel.

Animals↗
PubMed1989

Decreased interferon binding capacity of peripheral blood mononuclear cells during interferon treatment of chronic hepatitis B with special reference to (2'-5') oligoadenylate synthetase activity.

The levels of (2'-5') oligoadenylate synthetase (2-5 AS) activity and interferon (IFN) binding capacity were measured in peripheral blood mononuclear cells (PBMC) obtained from 9 patients with chronic hepatitis B (CHB) during IFN treatment. Six of the patients received human lymphoblastoid IFN (HLBI) or IFN-beta daily for 4 weeks at doses of 6 million units (MU); of the remaining three, 2 were treated on alternate days at doses of 3 MU for 5 weeks, and the other given daily IFN doses of 3 MU for 4 weeks. IFN binding was measured using HLBI (2 X 10(8) IU/mg protein) and completely purified 125I-labeled HLBI (290 Ci/mmol specific activity). The levels of 2-5 AS activity in PBMC were measured using radioimmunoassay. Before IFN treatment, the levels of IFN binding capacity were similar to those of normal subjects. During treatment, however, IFN binding capacity decreased significantly from 40 to 60% of initial levels 1 to 2 weeks after the start of treatment in the 7 patients receiving daily IFN, while in the remaining 2 patients given IFN on alternate days, IFN binding capacity did not decrease during treatment. On the other hand, 2-5 AS activity in PBMC increased during IFN treatment in all patients. Even after IFN binding capacity decreased in the 7 patients, the levels of 2-5 AS activity remained high during the remainder of treatment. These finding suggest that some mechanism other than IFN binding capacity may be responsible for the determination of 2-5 AS levels.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Determination of malonaldehyde in oxidized lipids by the Hantzsch fluorometric method.

Malonaldehyde is a secondary product formed during lipid oxidation. We developed a sensitive and reliable Hantzsch fluorometric method for determination of malonaldehyde in oxidized lipids. The principle of the method is based on the formation of highly fluorescent 1,4-dimethyl-1,4-dihydropyridine-3,5-dicarbaldehyde MI by reaction of malonaldehyde, methylamine, and acetaldehyde under neutral conditions. Compound MI formed could be estimated by high-performance liquid chromatography. Free malonaldehyde, that liberated under neutral conditions (labile forms) and that liberated by acid pretreatment (acid labile forms), could be determined by use of the calibration curves of MI versus malonaldehyde sodium salt. Oxidized methyl linoleate with a peroxide value of 1600 neq/mg contained 0.95 (free and labile) and 1.3 nmol (acid labile) malonaldehyde/mg, oxidized sardine oil with a peroxide value of 640 neq/mg contained 1.1 (free and labile) and 3.0 nmol (acid labile) malonaldehyde/mg, and the lipid fraction of oxidized rat liver microsomes contained less than 0.2 (free and labile) and 0.8 nmol (acid labile) malonaldehyde/mg. The malonaldehyde contents were much lower than those obtained by traditional 2-thiobarbituric acid test. It appears likely that the malonaldehyde contents, both free and labile, and acid labile forms, in oxidized lipids are too low to be taken into account.

Animals↗
PubMed1988

Induction of (2'-5')oligoadenylate synthetase in serum-starved HeLa S3 cells by growth factors and its role in growth regulation.

When serum-starved HeLa S3 cells were stimulated to proliferate by addition of fetal calf serum (FCS), (2'-5')oligoadenylate synthetase (2-5A synthetase) activity was induced. Although no interferon (IFN) activity was detectable in the HeLa S3 cell-conditioned culture medium after growth stimulation, addition of anti-IFN-beta monoclonal antibody inhibited both the expression of the 2-5A synthetase gene and the production of the enzyme, suggesting that endogenous IFN-beta was involved in 2-5A synthetase induction. Purified preparations of three growth factors, epidermal growth factor, platelet-derived growth factor, and insulin, also induced 2-5A synthetase through IFN-beta. When serum-starved HeLa S3 cells were treated with FCS, DNA synthesis was initiated synchronously, with peaks after 12 and 32 h, although the level of 2-5A synthetase reached a maximum after the first peak of DNA synthesis. Inhibition of 2-5A synthetase induction by anti-IFN-beta antibody enhanced the second, but not the first cycle of DNA synthesis. These results suggested that in HeLa S3 cells, after stimulation with growth factors the IFN/2-5A synthetase system played a role in cell growth negative regulatory mechanisms.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Characterization of L1210 S cells with low sensitivity to mouse interferon-gamma.

A mouse leukemic cell line L1210 Sg with a low sensitivity to interferon-gamma (IFN-gamma) was described. On the nature of the antiviral action and binding of IFN, L1210 Sg cells were compared with L1210 m cell line which is sensitive to IFN-gamma. For a half reduction of the vesicular stomatitis virus-RNA synthesis, L1210 Sg cells required 500-fold more IFN-gamma than L1210 m cells did. However, both cell lines were induced to the antiviral state to the same extent with IFN-alpha or -beta. L1210 Sg and L1210 m cells were sensitive to the anti-proliferative action of IFN-alpha and -beta, but insensitive to IFN-gamma. (2'-5')Oligoadenylate synthetase was induced in these cell lines by IFN-beta, but not by IFN-gamma, which suggests that the induction of this synthetase may not be responsible for the antiviral action of IFN-gamma. No substantial difference between L1210 Sg and L1210 m cells was found in IFN receptors for IFN-gamma and IFN-beta either in number per cell or in their affinity to corresponding IFN type. However, differences were noted in time course profiles of cell-associated IFN-gamma at 37 C: in L1210 m cells, a rise-and-decay profile of IFN-gamma bound to cells was observed at 37 C, but in L1210 Sg cells, rise and slight decay was observed. On the other hand, a similar rise-and-decay curve of IFN-beta bound to these cells was observed. These results indicated that the low sensitivity of L1210 Sg cells to IFN-gamma may be due to this slight decay of receptor-bound IFN-gamma.

Animals↗