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Biomedical subjects

T Takamoto

Publications and source records attributed to T Takamoto.

At least 55 records · Page 3Linked to original sources
PubMed1992

[A family of Marchesani syndrome with mitral valve prolapse and anuloaortic ectasia].

Marchesani syndrome consists of short statue, small spherical lens, glaucoma and brachydactyly, which are manifestations of hyperplastic connective tissue disease in systemic organs of mesodermal origin (Marchesani 1939). Among nearly 200 cases of Marchesani syndrome reported in the ophthalmology field, none has shown cardiac manifestations which typically characterize Marfan syndrome caused by hypoplastic connective tissue disorders. We experienced 2 cases which met the diagnosis of Marchesani syndrome and yet showed annuloaortic ectasia and mitral valve prolapse. A 30-year-old man and a 26-year-old woman who are siblings suffered from manifested brachydactyly, spherophakia, glaucoma and cardiac involvements. Their parents are in consanguinity. These unprecedented cases with mixed manifestations provide the evidence of possible gene-crossing between these 2 dystrophic mesodermal disorders.

Adult↗
PubMed1992

Reliability of Doppler echocardiographic stroke volume measurement.

To evaluate the accuracy and utility of the echocardiographic Doppler method of determining the stroke volume, the stroke volume was measured in 64 instances in 15 patients and compared to the simultaneous thermodilution stroke volume determinations. Stroke volume, varied by atrial pacing at various heart rates, was calculated noninvasively by the product of the cross-sectional area of the aortic orifice determined by echocardiography and the flow velocity integral measured by continuous wave Doppler. While the cardiac output was increased moderately by atrial pacing, the stroke volume was decreased in relation to the increase in the heart rate. The stroke volume calculated by the echo-Doppler method exhibited a significant linear relationship to the stroke volume determined by thermodilution (r = 0.84) and to the cardiac output (r = 0.75, p less than 0.01). Inter-observer and intra-observer variability was 7 +/- 4% and 5 +/- 4%, respectively. The noninvasive echo-Doppler method of estimating the stroke volume is concluded to be accurate, specifically, to be comparable to the values obtained by thermodilution and with a low inter- and intra-observer variability.

Adult↗
PubMed1991

Intraocular pressure and the rate of visual field loss in chronic open-angle glaucoma.

We measured the rate of change of visual field threshold values over time (mean follow-up, 44.9 +/- 17.4 months) by trend analysis in 40 eyes of 40 patients with chronic open-angle glaucoma. Twenty-eight eyes had stable visual fields, and two eyes had significant visual field improvement. Ten eyes had significant visual field deterioration and showed a correlation between indices of intraocular pressure (standard error of the mean, P = .02; standard deviation, P = .04; and range, P = .05) and the rate of visual field loss in the superonasal region of the visual field, such that the greater the variation of intraocular pressure the greater the rate of loss. The group losing visual fields had a higher mean visual field threshold value and significantly less optic disk pallor and cupping at the start of the study than the stable visual field group. Thus, a significant rate of visual field loss occurred at an earlier stage of the disease and showed a correlation with intraocular pressure in this stage.

Aged↗
PubMed1991

Increased preferential optic disc asymmetry in ocular hypertensive patients compared with control subjects.

The authors determined asymmetrical differences in optic disc cupping and pallor between the right and left eyes of 57 control subjects and 75 patients with ocular hypertension. Photogrammetry was used to measure the optic disc cup, and computerized image analysis was used to measure the optic disc pallor for the total disc and its quadrants. Generally, for control and ocular hypertensive eyes, the median values of cupping and pallor were significantly larger in the left eye than in the right, except for depth in the inferior quadrant (right eye minus left eye = 9.3%, P = 0.000) and pallor in the nasal quadrant (right eye minus left eye = 21.3%, P = 0.01), which were preferentially larger in the right eye than in the left in ocular hypertensive eyes. Ocular hypertensive eyes also showed a greater difference between the right and left eyes compared with control eyes for inferior depth (P = 0.06) and nasal pallor (P = 0.02). Detection of optic disc differences as a sign of ocular hypertension between the right eye and the left should evaluate the inferior and nasal quadrants of the disc.

Aged↗
PubMed1991

Glaucoma-like discs with subsequent increased ocular pressures.

Four patients with glaucoma-like discs, normal visual fields, and normal ocular pressures (less than 21 mmHg), first detected by direct ophthalmoscopy, were followed without treatment. Increased ocular pressures (greater than or equal to 21 mmHg) subsequently developed in these patients at an average of 8.1 years after the recognition of their glaucoma-like discs. Before the increased ocular pressure developed, two patients showed retinal nerve fiber layer loss and one showed optic disc hemorrhages. There are two possible hypotheses to explain this sequence of events. The first is that the optic discs and nerve fiber layer defects were produced by abnormal diurnal levels of ocular pressures or levels of ocular pressure, although less than 21 mmHg, which may be abnormal for the optic disc. The second hypothesis is that there are two independent events, one producing abnormalities in the optic disc and nerve fiber layer and a second producing the increased ocular pressure.

Aged↗
PubMed1991

Response of plasma atrial natriuretic factor to experimentally induced aortic and mitral regurgitation in dogs.

STUDY OBJECTIVE: The correlations between the plasma concentration of atrial natriuretic factor and right atrial or left atrial pressure were studied in experimentally induced aortic regurgitation and mitral regurgitation in dogs. DESIGN: Aortic regurgitation was created by opening the tip of a basket wire catheter placed at the aortic annulus via the left ventricular wall, and terminated by pulling back the catheter. To create mitral regurgitation a basket catheter was inserted into the mitral annular position via a pulmonary vein. Regurgitation was induced by opening the tip of the catheter, and terminated promptly by closing it. EXPERIMENTAL MATERIAL: Seven beagle dogs were prepared for the aortic regurgitation model and six for the mitral regurgitation model (weights 11.5 to 14.5 kg). MEASUREMENTS AND MAIN RESULTS: The plasma concentration of atrial natriuretic factor was highly correlated with right atrial pressure (r = 0.78, SD = 0.07, n = 7) and left atrial pressure (r = 0.82, SD = 0.05, n = 7) in aortic regurgitation; and with right atrial pressure (r = 0.82, SD = 0.05, n = 6) and left atrial pressure (r = 0.84, SD = 0.05, n = 6) in mitral regurgitation. Further evaluation of the molecular forms of plasma atrial natriuretic factor revealed the alpha form in all 13 dogs and the gamma form in two (one with aortic and the other with mitral regurgitation); no evidence of the beta form was seen. CONCLUSIONS: Atrial natriuretic factor secretion responds rapidly to the circulatory changes caused by valvular incompetence.

Animals↗
PubMed1991

Endothelin-1 induces hypertrophy with enhanced expression of muscle-specific genes in cultured neonatal rat cardiomyocytes.

To determine whether endothelin-1 (ET-1) induces hypertrophy of cardiomyocytes, the effects of ET-1 on the expression of muscle-specific genes and a proto-oncogene, c-fos, in cultured neonatal rat cardiomyocytes were examined by Northern blot analysis. ET-1 (10(-7) M) induced about twofold to fourfold increases in the gene expression of myosin light chain 2, alpha-actin, and troponin I after 6 hours, which continued up to 24 hours. The ET-1-induced increases in mRNA levels for these muscle-specific genes were dose dependent (10(-9) to 10(-7) M). Run-on transcriptional assay showed that the changes in mRNA level for three muscle-specific genes were regulated, at least in part, at the transcriptional level. 12-O-Tetradecanoylphorbol 13-acetate (TPA), a potent protein kinase C activator, and the Ca2+ ionophore ionomycin also increased mRNA levels of three muscle-specific genes. ET-1, TPA, and ionomycin similarly induced the expression of c-fos after 30 minutes, which returned to an undetectable level after 6 hours. ET-1 remarkably and dose-dependently stimulated accumulation of total inositol phosphates in cardiomyocytes. Morphometrical evaluation showed that ET-1 significantly increased surface area of cardiomyocytes without cell proliferation. ET-1 also dose-dependently stimulated the synthesis of protein and DNA, which was unaffected by the L-type calcium channel blocker nicardipine. These data suggest that ET-1 induces hypertrophy of cardiomyocytes associated with the induction of muscle-specific gene transcripts through the possible involvement of protein kinase C activation or intracellular Ca2+ mobilization.

Animals↗
PubMed1991

Norepinephrine inhibits human natural killer cell activity in vitro.

The effect of norepinephrine on human NK cell activity was investigated using a flow cytometry assay. NK cell activity was found to be inhibited by direct addition of norepinephrine to lymphocyte/target cell mixtures in a dose-dependent fashion. This inhibitory effect of norepinephrine was blocked by propranolol but not by atenolol. The results suggest that norepinephrine has a negative influence on NK cell activity and that the effect of norepinephrine is mediated via beta 2-adrenoceptors.

Atenolol↗
PubMed1991

[Doppler hemodynamic evaluation of bioprosthetic valve failure in the mitral position].

M-mode and two-dimensional echocardiography (2DE) allows the accurate assessment of primary tissue degeneration of bioprosthetic valves. The Doppler method permits quantitative evaluation of the pressure gradient across the prosthetic valve or detection of regurgitant flow. The present study summarized our clinical experiences of serial cases of mitral valve replacement (MVR) with bioprostheses at the mitral position, and clarified the clinical usefulness and limitations of Doppler and 2DE examinations for the early detection of primary valve dysfunction. Consecutive 65 patients undergoing single mitral valve replacement from April, 1977 to November, 1979 were listed for the study. A survey of the present clinical status was carried out from July, 1988 to July, 1990 (a follow-up period ranged from 84 to 127 months) for all patients, and the information was available from 53 patients (47 adults and six infants). Twenty-four survived patients without re-MVR were examined by Doppler and 2DE. Among the 53 patients, 34 were alive and 19 dead, and the total survival rate was 64.2%. The reasons for death in 19 patients were perioperative death in seven (including four infants with severe calcification of bioprostheses), chronic heart failure in three, cerebral infarction in two, post blood transfusion hepatitis in two, endocarditis in one, and non-cardiac death such as cancers in four. During the long-term observation of 47 adult patients, 14 cases (30%) had re-MVR (one for a stenotic lesion with massive calcification, and 13 for torn leaflets). Thickening and/or torn leaflets were noted in 13 (54%) of the 24 survived patients without re-MVR.2+ suggests that bioprosthetic valve replacement at the mitral position may not be recommended.

Adult↗
PubMed1991

[The prevalence and clinical features of pathologically abnormal mitral valve leaflets (myxomatous mitral valve) in the mitral valve prolapse syndrome: an echocardiographic and pathological comparative study].

We studied the prevalence and clinical features of pathologically abnormal mitral valve leaflets (myxomatous mitral valve: MMV) in consecutive 142 patients with the mitral valve prolapse syndrome (MVP). Our echocardiographic criteria for MMV were 1) thick leaflets 3 mm or greater, 2) redundant leaflet-motion, and 3) echo-density lower than that of the aortic walls. The echocardiographic measurements of left ventricular diastolic dimensions (LVDd), percent fractional shortening (%FS), mitral annular diameter (MAD), and LV mass were compared between MMV and non-MMV groups. Twelve patients (8%) were referred for surgery because of congestive heart failure, and two patients died during the observation periods. Gross morphology of the MMV was characterized by increased surface area, dome formation of the leaflet-body, and non-uniform leaflets in thickness, and histologic findings of the MMV were the infiltration of spongiosa layer into the fibrosa layer. The diagnostic accuracy of echocardiography for the MMV was examined in 14 patients underwent either surgery or autopsy, and it was high (78% in sensitivity and 80% in specificity). The progression of mitral regurgitation (MR) from mild to moderate grade or mild to severe grade was found in five of 26 patients during follow-up studies over 12 months (mean = 36 months). All of the five patients were aged 50 years and older. While, MR completely disappeared in a 17-year-old boy with marked physical development within three years of the observation period. Mitral annular diameter significantly increased in MMV with MR when compared to non-MMV with MR (4.1 +/- 0.7 vs 3.5 +/- 0.4). But no significant changes were noted in LVDd and LV mass between non-MMV with MR and MMV with MR. Of the 142 patients with MVP, 96 patients were non-MMV and 46 patients were MMV. Ruptured chordae tendineae were associated in 5/96 patients (5%) with non-MMV and 22/46 patients (48%) with MMV. Intracardiac vegetations were seen in four of the 96 patients (4%) with non-MMV. The prevalence of MMV in MVP was greater in older patients, and it reached nearly as high as 50% of MVP patients aged 60 years and older. In conclusion, the echocardiographic diagnostic criteria for MMV are reliable with high sensitivity and specificity, and are useful to predict the high risk patients in the MVP syndrome. MMV may be a potential etiology causing aggravation of mitral regurgitation and/or ruptured chordae tendineae.

Adolescent↗
PubMed1990

Hemodynamic changes by recombinant erythropoietin therapy in hemodialyzed patients.

Recombinant human erythropoietin therapy was given to 15 patients undergoing long-term hemodialysis with normal cardiac function. None of the patients had hypertension before the erythropoietin therapy and had received no antihypertensive agents. Before and after the erythropoietin therapy M-mode and pulsed Doppler echocardiographic studies, measurements of plasma volume by radioiodinated human serum albumin, and measurements of atrial natriuretic factor were carried out. After 6 weeks of erythropoietin therapy, hematocrit increased from 20.0 to 33.0%. Cardiac output, stroke volume, left ventricular diastolic dimensions, and left ventricular wall stress were all significantly decreased. Total peripheral resistance, interventricular septal thickness, and left ventricular posterior wall thickness were significantly increased. In Doppler echocardiographic studies, the mean velocity of aortic ejection flow and left ventricular acceleration time were decreased. The blood volume derived from plasma volume and hematocrit was not changed, whereas plasma atrial natriuretic factor concentration was significantly decreased. These data suggest that recombinant human erythropoietin administration suppressed the hyperdynamic cardiac state that was required to maintain oxygen delivery to the peripheral tissues in severe uremic anemia.

Adult↗
PubMed1989

Glaucomalike disks without increased intraocular pressure or visual field loss.

We studied 48 patients who had glaucomalike disks with increased cupping and pallor, superior or inferior extension of cupping and pallor and asymmetry of cupping and pallor between eyes without increased intraocular pressure or visual field loss, and open angles. We compared these patients with a randomly selected group of 48 patients with primary open-angle glaucoma. The mean age of the patients with glaucomalike disks (45.1 +/- 16.1 years) was significantly younger than the group with open-angle glaucoma (63.8 +/- 11.3 years). Of the patients with glaucomalike disks, 11 (23%) had a family history of glaucoma, 75% of 22 eyes with optic disk fluorescein angiograms had abnormal readings, and 59% of 43 eyes with retinal nerve fiber layer defects had abnormal readings. Photogrammetric measurements of the left disk cups were compared in 22 of the patients with glaucomalike disks to 16 matched patients with primary open-angle glaucoma. The only statistically significant difference was that the patients in the glaucoma group showed a larger cup area (surface opening) of the inferior quadrant. Our findings suggest that some glaucomalike disks may be one variant of primary open-angle glaucoma.

Adult↗
PubMed1989

A large myxoma of the right atrium demonstrated by thallium-201.

A rare case of right atrial myxoma in which thallium-201 gave a good delineation of the tumor was presented. In this case, the feeding arteries were seen to be highly developed on coronary arteriogram. The amount of blood containing thallium-201 supplied to the tumor through the feeding arteries was so great that the tumor was considered to be visualized by thallium-201 imaging.

Aged↗
PubMed1989

Photogrammetric measurement of nerve fiber layer thickness.

To measure retinal nerve fiber layer (NFL) thickness, three sets of simultaneous stereophotographs of the optic disc, taken with the Donaldson fundus camera, were measured at 5 degrees intervals in a stereoplotter (Kern PG2) at the surface of the internal limiting membrane (ILM) and the retinal pigment epithelium (RPE) along the disc margin. The NFL thickness was expressed as a ratio of the vertical disc radius. The reproducibility of the method showed that the percent coefficients of variation (CV%) for 15 normal, 10 ocular hypertensive, and 10 glaucomatous subjects were 5.2%, 6.0%, and 3.9%, respectively. The presence of a halo or scleral crescent had no significant effect on reproducibility. The photogrammetric technique for measuring NFL thickness appears to be highly reproducible and sensitive and may be a valuable quantitative method for: (1) early detection of optic nerve damage from glaucoma and other optic neuropathies and (2) monitoring progression of retinal NFL defects.

Adult↗
PubMed1989

Lymphocyte subsets in patients with acute myopericarditis, arrhythmias and dilated cardiomyopathy.

To investigate the role of immunoregulatory function in determining the clinical course of acute myopericarditis, lymphocyte subsets were analysed by laser flow cytometry in 20 patients with acute myopericarditis, 30 with various arrhythmias or atrio-ventricular block and 31 with dilated cardiomyopathy. During the healing stage of acute myopericarditis, patients with residual electrocardiographic or left ventricular wall motion abnormalities presented altered frequencies of lymphocyte subsets, increased B 1 and reduced OKT 8 positive cells with an elevated OKT 4/8 ratio. The abnormal pattern was not evident in patients with acute pericarditis nor in those with acute myocarditis who recovered completely without residual abnormalities. This observation suggested that an imbalance of helper/suppressor T cells could modulate the clinical course of acute myopericarditis, either by producing extensive and irreversible myocardial damage during acute illness or by inducing chronic smoulding myocardial inflammation. Patients with ventricular arrhythmias and left ventricular wall motion abnormalities also presented reduced suppressor/cytotoxic T cells, implying that they had been suffering from chronic smoulding myocarditis mediated by immunoregulatory dysfunction. However, we could not determine whether the imbalance of helper/suppressor T cells could mediate the progression from myocarditis to dilated cardiomyopathy, since no association was demonstrated between the abnormal lymphocyte subsets and mononuclear cell infiltration in endomyocardial biopsy sample from patients with dilated cardiomyopathy.

Acute Disease↗
PubMed1989

Monoclonal antibody to phospholamban isolated from bovine cardiac muscle.

Phospholamban, a putative protein regulator of the Ca2(+)-dependent ATPase in cardiac sarcoplasmic reticulum, was isolated from bovine cardiac microsomes using a low concentration of the detergent. The phospholamban was phosphorylated by cyclic AMP-dependent protein kinase to a level of 7.55 nmol of phosphate per mg of protein. This molecular weight was found to be 20,000 dalton based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Monoclonal antibody against the bovine phospholamban was made by the hybridoma technique. The specificity of the monoclonal antibody was determined by immunoblotting experiments and the antibody was shown capable of blocking the phosphorylation of phospholamban by cyclic AMP-dependent protein kinase. The immunoglobulin subclass of the antibody was identified as IgG1. The distribution of phospholamban in muscular tissues was observed by the immunohistological method and the results showed that myocardial cells were strongly and specifically stained, while skeletal and smooth muscle cells were stained at the background level. The results showed the phospholamban in the ventricular muscle to be localized along the cellular surface and in a network over the myofilaments. The monoclonal antibody identified a reactive component in the myocardial cells of monkey, canine, mouse and man.

Animals↗
PubMed1989

[Effects of hemodialysis on left ventricular performance: a Doppler echocardiographic study].

Left ventricular systolic and diastolic performance was examined using Doppler and M-mode echocardiography in 42 patients with chronic renal failure before and after hemodialysis. Twenty patients with left ventricular hypertrophy, 22 without hypertrophy and 30 normal subjects were studied. Chronic renal failure patients showed significantly larger chamber diameters of the left ventricle, left atrium and right ventricle than did normal subjects. This group also exhibited greater fractional shortening, stroke volume and cardiac output. Before hemodialysis, patients with left ventricular hypertrophy had a significantly higher cardiac output and the greater ratio of late to early diastolic peak flow velocities (A/R) than did patients without hypertrophy. After hemodialysis, there were significant reductions in blood pressure, ventricular and atrial dimensions, stroke volume and cardiac output. The velocities of early and late diastolic left ventricular filling and the deceleration rate were also significantly reduced. The heart rate, A/R, deceleration half time, and the ratio of deceleration half time to acceleration half time (DHT/AHT) were significantly increased. The greater the amount of fluid removed, the greater the changes in the above values. Patients with left ventricular hypertrophy exhibited significant reductions in fractional shortening, ejection fraction, stroke volume and cardiac output, compared to those without hypertrophy. However, patients without hypertrophy showed more significant decrease in the acceleration half time and increase in DHT/AHT than did patients with hypertrophy. These findings demonstrated normal systolic function and impaired diastolic properties in patients with chronic renal failure, who had left ventricular hypertrophy unaccompanied by dilatation.

Adult↗