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Biomedical subjects

T Akatsuka

Publications and source records attributed to T Akatsuka.

72 records · Page 4Linked to original sources
PubMed1985

MRL/Mp-lpr/lpr mouse derived monoclonal antibodies that recognise determinants shared by poly (ADP-ribose), single stranded DNA and left handed Z-DNA.

MRL/Mp-lpr/lpr (MRL/l) mice spontaneously produce antibodies to poly(ADP-ribose) that are cross-reactive with single stranded DNA (ssDNA). Spleen cells from these animals were used for fusion with murine plasmacytoma cells to prepare hybridomas that produce autoantibodies to poly(ADP-ribose). Monoclonal antibodies (MoAb) produced by the selected hybridomas not only preferred ssDNA to poly(ADP-ribose), but also reacted with left handed Z-DNA; the MoAb reflected the nature of serum antibodies to poly (ADP-ribose) in MRL/l mice. These results suggest that similar antigenic determinants exist in poly (ADP-ribose), ssDNA and left handed Z-DNA and that the cross-reactive nature of autoantibodies to poly (ADP-ribose) in MRL/l mice may be the results of expansion of such clones as selected in this experiment.

Animals↗
PubMed1985

Use of L-leucyl-3-carboxy-4-hydroxyanilide as substrate for determining the activity of microsomal aminopeptidase in serum.

We describe a colorimetric method for assay of microsomal aminopeptidase (EC 3.4.11.2) activity in serum. We use a new substrate, L-leucyl-3-carboxy-4-hydroxyanilide, p-xylenol as coupler, and sodium metaperiodate as oxidizing reagent. The colored substance formed by the oxidative condensation between p-xylenol and 5-aminosalicylic acid absorbs maximally at 635 nm, and can be directly measured in serum. In a previous method for this enzyme, L-leucyl-beta-naphthylamide was used as substrate and beta-naphthylamine, a carcinogenic reagent used as a standard in making the assay, was unsuitable for routine use. We found a close correlation between results obtained with the new, safer method and with the previous method.

Aminopeptidases↗
PubMed1985

DNA affinity column chromatography: application in the isolation of distinct antibody populations from SLE sera.

An improved method was developed for purification of anti-DNA antibodies by single-stranded DNA (ssDNA), or double-stranded DNA (dsDNA) affinity column chromatography. The effectiveness of this method was examined by measuring the recoveries and purifications of various monoclonal and polyclonal antibodies. Results showed that this method gave good recoveries and purifications of anti-DNA antibodies. Furthermore, by this method, it was possible to isolate antibody populations with distinct specificities from polyclonal antibodies, as shown by enzyme linked immunosorbent assay (ELISA). Therefore, this method should be useful for characterization of polyclonal antibodies in the sera of patients with systemic lupus erythematosus (SLE) as well as of autoimmune lupus mice.

Animals↗
PubMed1985

[Quantitative analysis of myocardial perfusion by digital subtraction angiography].

Digital subtraction angiography (DSA) has been adopted to detect ischemic myocardial areas and to quantitatively evaluate the degrees of myocardial perfusion abnormalities. Subtraction for selective coronary arteriography was performed sequentially between mask and enhanced images in the same cardiac phases by means of ECG signals. We obtained three distinct perfusion phases which we termed the arterial, capillary, and venous phases. Densitometry of the circumferential cardiac wall was performed on these sequential images. The results were compared with 201Tl myocardial scintigrams and cine angiograms. In the arterial phase, the abnormalities of the coronary artery, such as stenosis, obstruction and collaterals were represented. In the capillary phase, contrast materials served as markers of myocardial perfusion and delineated infarctions as areas of low contrast enhancement compared to the normally perfused myocardium. In the venous phase, the infarcted areas were represented as areas with greater relative contrast enhancement than that of the normal myocardium. Circumferential analysis of perfusion could provide more detailed information about myocardial ischemic areas and the degrees of ischemia. Although we used invasive selective coronary arteriography, DSA techniques have numerous merits such as excellent temporal resolution, spatial resolution, and good contrast resolution, over conventional methods. Quantitative DSA methodology which we developed provided not only anatomical information about the main coronary arteries but new information about abnormalities of peripheral myocardial perfusion.

Angiography↗
PubMed1985

[Regional myocardial perfusion abnormality detected by digital subtraction angiography in a case of patent ductus arteriosus with coronary arterial fistulae].

A 19-year-old woman with patent ductus arteriosus and increasingly severe chest pain received various examinations including exercise stress radionuclide test, which revealed hypokinesis and decreased myocardial perfusion in the apex and left ventricular dilatation. Conventional selective coronary arteriography and newly-developed ECG synchronized digital subtraction angiography (DSA) were performed to identify the genesis of her myocardial ischemia. Selective coronary arteriography revealed congenital coronary arterial fistulae in the right and left coronary arteries. The largest fistula was observed around the obtuse marginal artery terminating in the left ventricle. Although stenosis of the left circumflex and left anterior descending arteries (LAD) were not observed, the LAD appeared to be hypoplastic. Hypoplasia of the LAD and the steal phenomenon by arterial fistula could have been responsible for the myocardial ischemia in the apex, but this method did not clearly reveal the area and the degree of myocardial ischemia in the apex. Sequentially subtracted images during the arterial and capillary phases were obtained by utilizing ECG-synchronized DSA for selective coronary arteriography. For these images, densitometric analysis was adapted to the myocardial region, i.e. circumferential densitometry using 21 segments around the left ventricular wall. Decreased myocardial perfusion was clearly demonstrated in the apex in capillary phase images. Moreover, circumferential analysis provided detailed information about the area and the degree of impaired peripheral circulation in the myocardium. This analysis by DSA may prove useful for evaluating myocardial perfusion abnormalities.

Adult↗
PubMed1983

Effect of exercise on left ventricular diastolic filling in athletes and nonathletes.

To evaluate the effect of exercise on left ventricular diastolic filling, the following were measured at rest and during exercise in 14 control subjects and 15 athletes, using digitized M-mode echocardiography: the peak early diastolic lengthening rate of the left ventricular dimension and the filling volume and the filling fraction during the first 0.10 s of diastole. During ergometer exercise performed at a level that increased the heart rate to 100 beats/min, there were significant increases in the peak normalized lengthening rate of the left ventricular dimension (control subjects, 4.2 +/- 1.3 vs. 6.1 +/- 1.1 s-1, mean +/- SD, P less than 0.001; athletes, 5.3 +/- 0.9 vs. 7.4 +/- 1.1 s-1, P less than 0.001), filling volume (control subjects, 15 +/- 12 vs. 33 +/- 10 ml, P less than 0.001; athletes, 21 +/- 12 vs. 63 +/- 18 ml, P less than 0.001), and filling fraction (control subjects, 21 +/- 14 vs. 42 +/- 17%, P less than 0.005; athletes, 21 +/- 13 vs. 54 +/- 12%, P less than 0.01). The peak lengthening rate of the left ventricular dimension, the filling volume, and the filling fraction were significantly greater in athletes than in control subjects during exercise (P less than 0.005, P less than 0.001, and P less than 0.05, respectively). Augmented early diastolic filling may be a mechanism to provide adequate filling for the ventricle at high heart rates produced by exercise, especially in athletes.

Adolescent↗
PubMed1983

[Contrast echocardiography of the left heart by intravenous injection of perfluorochemical emulsion].

We evaluated a new method of contrast echocardiography of the left heart utilizing the intravenous injection of perfluorochemical emulsion (PFC emulsion: Fluosol-DA 20 W/V%: Green Cross Corp), which was prepared as artificial blood. Observations were made in 18 open-chest dogs. To assess the possibility of detection of mitral valve regurgitation and myocardial perfusion by this method, a small series of experiments were made. Results were as follows: Following the appearance of contrast echoes in the right heart after the injection of PFC emulsion (10 ml) into the inferior vena cava, the left heart contrast echo images were clearly obtained in 16 of the 18 dogs, and they were visible but weak in the remainder 2. The solution of surfactants (Pluronic F-68, yolk phospholipids, and glycerol), which were added to Fluosol-DA, was also used as contrast agent in 6 dogs. The left heart was also opacified by contrast echoes after intravenous injections. However, the density of the left heart contrast echoes appeared lower, as compared with that after the injection of PFC emulsion. When oxygen (95%) was mixed in PFC emulsion or inhaled through the intratracheal tube, the left heart contrast images were slightly enhanced. In 4 of 6 dogs with surgically created mitral valve regurgitation, systolic contrast echoes in the left atrial cavity were detected on the M-mode echograms after the intravenous injection of PFC emulsion (15 ml). These echoes appeared to move across the mitral valve from the left ventricle to the left atrium or away from the mitral valve in the left atrium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

[Comparison of variability (STV and LTV) indices by computer-simulated data].

Many investigators have proposed their own formula for quantitative evaluation of STV (short term variability) and LTV (long term variability). There has even been confusion over the definition itself of STV. We compared those indices by using 'beat to beat interval' computer-simulated series and found that there is little difference between the STV indices. According to the definition of STV by the Japan Society of Obstetrics and Gynecology, it is the variance in beat to beat difference, which is determined by the variance in beat to beat intervals and the autocorrelation function of the same intervals. For all the 2,500 combinations of the variability and the autocorrelation, normal random interval series were generated by the computer and five indices (Dalton, Cabal, Yeh, Heilbron and de-Haan) were compared with calculated index values using these interval series. Assigning the variability and the autocorrelation to the X-axis and the Y-axis respectively, the Z-axis was used to indicate the value of the STV. Five curved surfaces thus formed have a similar shape, which shows us that these STV indices behave the same way in accordance with the change in STV. Further, the study of LTV indices with the same simulated data showed that Yeh's LTV index indicates only the variability but has no relation-ship with the autocorrelation and both de-Haan and Heilbron's LTV indices represent the variability and the autocorrelation. However, they increase as the autocorrelation increases unlike the STV indices.

Computers↗
PubMed1980

Restricted expression of endogenous N-tropic XC-positive leukemia virus in hybrids between G and AKR mice: an effect of the Fv-4r gene.

G mice carrying the Fv-4r gene are resistant to exogenous infections of various strains of ecotropic MuLVs (Suzuki, 1975). The expression of endogenous N-tropic XC-positive virus was studied in the progency of a cross between G and AKR mice. In the F1 mice, the virus expression was almost completely supressed, and no leukemia developed during 1 year of observation. Results of successive backcrossings with AKR mice indicated that a single dominant gene, the Fv-4r suffices for supression. It can be concluded that the extensive growth of N-tropic XC-positive virus is a prerequisite for leukemia development in AKR mice.

Animals↗
PubMed1975

Carcinogenesis in tissue culture 24: tumorigenicity and aggregate-forming capacity of mammalian cells in culture.

Twenty two kinds of strains and substrains of mammalian cells were cultivated on a gyratory shaker to obtain cell aggregates. The relationship between the morphology of aggregates and tumorigenicity of the cells was investigated. In some groups of cells, the size of aggregates corresponded with their tumorigenicity, e.g. among rat liver cells untreated, hepatoma cells produced by back-transplantation of rat liver cells after the treatment with a chemical carcinogen in tissue culture, and the hepatoma cells passaged serially through rats. The correspondence, however, was generalized to not all the cell strains. It was impossible to identify the tumorigenicity of cells by their aggregate-forming capacity.

4-Nitroquinoline-1-oxide↗