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Biomedical subjects

M Hayasaka

Publications and source records attributed to M Hayasaka.

15 recordsLinked to original sources
PubMed1991

The stem cells of a primordial germ cell-derived teratocarcinoma have the ability to form viable mouse chimeras.

A euploid testicular teratocarcinoma line, STT-3, has been established from a tumor spontaneously occurring in the testis of a 129/Sv-ter male. Developmental ability of the STT-3 stem cells was tested by injecting these cells into mouse blastocysts. The frequency and the extent of chimerism were examined in mid-gestational fetuses and in live-born mice. STT-3 stem cells form viable chimeras at a high rate and differentiate into normal tissues. This is the first reported testicular teratocarcinoma-derived stem line with a proven capacity to form viable chimeric mice upon injection into the blastocysts.

Animals↗
PubMed1991

A stable cellular marker for the analysis of mouse chimeras: the bacterial chloramphenicol acetyltransferase gene driven by the human elongation factor 1 alpha promoter.

We have developed a method of marking of mouse cells by means of transfection of a foreign gene. The transgene chosen here was the plasmid pEF321CAT which contains the bacterial chloramphenicol acetyl transferase (CAT) gene linked to the promoter region of the human polypeptide chain elongation factor 1 alpha (hEF1 alpha) gene. Evaluation of the plasmid pEF321CAT as a cellular marker for mouse cells involved intensive examination of a transgenic mouse carrying pEF321CAT. The CAT gene was expressed in all tissues examined, demonstrating that the hEF1 alpha promoter was active in a wide range of mouse cells. The plasmid itself did not exert any harmful effect on the normal development of mice, and the CAT activity was immunohistologically detectable on sectioned tissues by the use of anti-CAT serum. When the plasmid was transferred into embryonal carcinoma (EC) cells and embryonic stem (ES) cells, the CAT gene was also found to be expressed constantly irrespective of their differentiation. These results demonstrated that the plasmid pEF321CAT can be used as a reliable and feasible cellular marker that would distinguish unequivocally the cells of each of genotype in chimeric tissues.

Aging↗
PubMed1988

Embryonic stem cell-mediated transfer and correct regulation of the chicken delta-crystallin gene in developing mouse embryos.

To study regulation of delta-crystallin expression during ontogeny, we transferred the gene from chicken into developing mouse embryos by first transforming an embryonic stem (ES) cell line of mouse and then producing chimaeric embryos by combining them with normal mouse embryos. Using this technique, genes were transferred into a variety of developing mouse tissues with high efficiency. Two delta-crystallin gene constructs were used: the wild-type gene with 2200 bp of the 5' flanking sequence, shown to be lens-specific in an assay using cultured mouse cells, and a mutant gene with 51 bp of the 5' flanking sequence, lacking the sequence required for expression in lens cells. Five independent lines carrying the former and two lines carrying the latter were employed in producing chimaeras. In the chimaeric embryos having the wild-type gene, delta-crystallin was expressed in the lens and in specific regions of the primitive central nervous system (CNS) as is seen in embryonic expression in the chicken. In adult mouse chimaeras also, expression was restricted to the lens and the CNS, in the pyramidal neurones of the piriform cortex and the hippocampus. delta-crystallin expression in these tissues is due to proper transcriptional regulation, since no expression was observed when chimaeras were produced with the ES lines carrying the mutant gene. The experimental results reported here demonstrate the advantage of ES-cell-mediated gene transfer in the study of embryonic gene regulation, because a number of gene constructs and chromosomal sites can be analysed shortly after embryo manipulation without requiring gene transmission to the next generation.

Animals↗
PubMed1987

Segmental wall motion abnormalities in dilated cardiomyopathy: hemodynamic characteristics and comparison with thallium-201 myocardial scintigraphy.

This study assessed the hemodynamic characteristics of segmental wall motion abnormality of the left ventricle in patients with dilated cardiomyopathy (DCM) and its relation to the thallium-201 (TI-201) myocardial scintigraphy (MPI). Left ventriculograms and MPI in 23 patients were analyzed by the use of quantitative indexes of regional wall motion and TI-201 uptake based on a mean and a standard deviation of 13 normal subjects. Relative normokinesis in our definition was more frequently seen in the inferior wall than in the anterior wall (p less than 0.01). In contrast, severe asynergy was more often seen in the anterior wall than in the inferior wall (p less than 0.01). There were 11 patients who had relative normokinesis and asynergy together. By means of the index of wall motion, the DCM patients were divided into two groups, one with segmental wall motion abnormality (SWMA) and another with diffuse wall motion abnormality (DWMA). The DWMA group had higher left ventricular end-diastolic pressures (p less than 0.05) and the tendency of large left ventricular end-diastolic volumes than the SWMA group. There was a rough correlation (r = 0.58) between the quantitative indexes of TI-201 uptake and wall motion at the same region of the left ventricle. Thus, the nonuniformity of the left ventricular wall motion was recognized in the patients with DCM and more increased preload was shown in the patients with DWMA than in the group with SWMA. Further, the regional asynergy may be related to the localized fibrosis within the left ventricle in DCM, considering the result that the worse TI-201 uptake was roughly accompanied by the more severe asynergy.

Adult↗
PubMed1986

[Severity and extent of coronary artery disease and their relationship to left ventricular functional reserve in the chronic disease state].

Our previous observations showed that left ventricular wall motion abnormality (asynergy) induced by stress was observed in the phase response of radionuclide technique, and the severity and extent of coronary artery disease (CAD) assessed by the Pujadas score (PS) correlated well with the maximal phase delay response (delta MPD) but not with the ejection fraction response (delta EF) in patients with CAD without old myocardial infarction (MI). This study evaluated the usefulness of EF, MPD and the first-third filling fraction (FF, divided by the volume accrued throughout diastole) at rest and during stress, using ergometer and first-pass radionuclide angiocardiography (RNA), to determine the severity of CAD, and to evaluate any abnormalities in the systolic and diastolic coupling in left ventricular function during stress. Seventy-four patients with significant CAD, including 41 with previous transmural MI (MI group) and 33 without MI (angina group) were the subjects of this study. EF at rest and during stress inversely correlated, and MPD on stress linearly correlated with PS in angina group with PS greater than 10, while no such correlations were found in MI group. A normal EF response (delta EF greater than or equal to 5%) was accompanied by a greater-than-normal response in FF (delta FF) in both groups. A lower EF response was accompanied by a smaller delta FF in angina group, but by a larger delta FF in MI group. The difference was statistically significant (p less than 0.03), without significant differences by age, PS, peak heart rate, systolic blood pressure, and ischemia on ECG during stress. Resting EF and FF by the RNA method correlated with those by left ventriculography (LVG), respectively. It was suggested that RNA is an accurate method for determining EF and FF, while phase analysis may provide some additional information different from that provided by LVG. We concluded that EF and MPD during stress are as useful as delta MPD with the exception of a few cases in predicting the severity of CAD, and that scar tissue within the ventricular wall in MI may play an important role in determining the ventricular diastolic mechanical property during stress.

Angina Pectoris↗
PubMed1985

[Functional reserve of the ischemic left ventricle with ventricular aneurysm to afterload stress: digital subtraction angiographic assessments].

Digital subtraction angiography (DSA) has been confirmed to be an accurate method for determining left ventricular function. It is a relatively non-invasive technique without inducing premature ventricular complexes. The response of left ventricular function to afterload stress was assessed using DSA for eight patients with old anterior myocardial infarction and ventricular aneurysm including that of the anterior wall (averaging 30.3 months after the acute episodes). Their ages ranged from 36 to 65 years and one patient was a woman. Prior to the investigation, we confirmed that a single DSA procedure did not alter left ventricular function in a pilot study of one patient (No. 8). After initial DSA in the basal state, methoxamine was infused intravenously (1 to 2 mg/min). When aortic systolic blood pressure increased by 30 to 50 mmHg, a second DSA was performed for each patient. Left ventricular volumes and ejection fractions were calculated by the area-length method, and regional wall motion was assessed by the visual method according to the AHA classification and the curvature radius of the apical ventricular aneurysm was calculated. Methoxamine induced neither acute heart failure nor angina pectoris in the present series. The heart rates decreased, and there were a significant increase in end-systolic volumes (p less than 0.05), end-systolic radii (p less than 0.05), and a significant decrease in ejection fractions (p less than 0.02) after methoxamine infusion. In 32 of 40 segments, regional wall motion was unchanged by methoxamine as assessed by the visual method; whereas, in the other eight, there was a deterioration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗