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Biomedical subjects

Y Koga

Publications and source records attributed to Y Koga.

At least 415 records · Page 23Linked to original sources
PubMed1988

Plasma and right auricle concentrations of atrial natriuretic polypeptide in children with cardiac diseases.

To investigate the atrial natriuretic polypeptide (ANP) levels in congenital heart diseases, we measured plasma immunoreactive ANP (ir-ANP) in 29 patients with left-to-right shunt, and right auricle ir-ANP in 25 patients who underwent operation. The levels of ir-ANP in the pulmonary artery correlated with that in the femoral vein (r = 0.95, P less than 0.001), mean pulmonary arterial pressure (r = 0.74, P less than 0.001) and right atrial pressure (r = 0.53, P less than 0.01). The right auricle ir-ANP level was high in patients with heart failure combined with pressure or volume overload of the right atrium, as observed in tricuspid atresia, complete endocardial cushion defect, and total anomalous pulmonary venous drainage. These results suggest that the production of ANP in the atrium increases as a compensatory or secondary response to persistent release of ANP into the circulation in cardiac diseases.

Adolescent↗
PubMed1988

Muscle pathology in cytochrome c oxidase deficiency.

Muscle biopsies from 16 patients with cytochrome c oxidase (CCO) deficiency were examined morphologically. Two siblings had the fatal infantile form. The muscle of the older sister at the age of 5 months had numerous ragged-red fibers (RRF) and increased numbers of lipid droplets; at 28 days the brother had no RRF suggesting that the RRF formed later than 28 days. The muscle pathology in two patients with the benign infantile form improved as they grew older; numbers of RRF, lipid droplets and glycogen particles decreased and CCO activity increased in the second biopsy. In the encephalomyopathic form, RRF were seen in 5 of 12 muscles mostly in patients more than 6 years of age. Muscle spindles and blood vessel walls in the biopsies from three patients with rapid clinical aggravation had no CCO activity, suggesting that enzyme activity differed from tissue to tissue (tissue specificity).

Adolescent↗
PubMed1988

Variability in the activity of respiratory chain enzymes in mitochondrial myopathies.

Four patients with mitochondrial abnormality had multiple muscle biopsies at several year intervals during which respiratory chain enzyme activities were shown to be quite variable. In three patients, progression of the disease paralleled the decrease in respiratory chain enzyme activity. In one patient, the clinical and pathological findings improved with age as is seen in the benign infantile form of cytochrome c oxidase (CCO) deficiency. The variability in these mitochondrial disorders may result from the varied proportions of normal and abnormal mitochondria in the muscle cells in which the mitochondria are said to be randomly replicated from numerous mitochondrial DNA copies.

Adolescent↗
PubMed1988

Impaired myocardial perfusion in patients with hypertrophic cardiomyopathy: assessment with digital subtraction coronary arteriography.

To study the clinical significance of abnormal myocardial perfusion in patients with hypertrophic cardiomyopathy (HCM), we performed a computerized washout analysis of digital subtraction coronary arteriograms in 28 patients with HCM and 16 control subjects. The contrast disappearance half-life (T1/2) was calculated from a time-density curve generated in the four sectors of the myocardium perfused by the left anterior descending coronary artery and the mean T1/2 was calculated by averaging T1/2 values for these four sectors. Patients with HCM demonstrated longer T1/2 in the ventricular septal region than control subjects. Thirteen (46%) of the patients with HCM presented abnormally longer mean T1/2 values, suggesting impaired myocardial perfusion. Family histories of HCM were more frequent in patients with abnormal mean T1/2 values (92% vs 47%; p less than 0.05). On the exercise stress test, patients with abnormal T1/2 values presented significantly lower exercise tolerance with more frequent exercise-induced ST segment depression (62% vs 13%; p less than 0.05). However, there were no significant differences between the two groups with regard to ventricular wall thickness, left ventricular end-diastolic pressure, or the severity of systolic narrowing of the coronary arteries. These findings suggest that 13 (46%) of the patients with HCM have impaired myocardial perfusion, which may be a manifestation of intramural coronary artery disease in addition to left ventricular hypertrophy, elevated left ventricular end-diastolic pressure, or systolic narrowing of the coronary arteries. Additionally, significant association of the prolonged T1/2 with a familial occurrence of HCM and depressed exercise tolerance with ST segment depression imply that impaired myocardial perfusion could be an important inherent pathophysiological state leading to myocardial ischemia during exercise.

Adolescent↗
PubMed1988

Tricuspid regurgitation due to chest trauma: an unusual laceration around the annulus of the anterior leaflet.

A 70-year-old male with tricuspid regurgitation due to a blunt chest trauma inflicted 16 years previously underwent prosthetic valve replacement. At surgery, a tear, which produced tricuspid regurgitation, was found around the annulus of the anterior leaflet of the tricuspid valve. Since this area has not been reported as a location for heart trauma-producing tricuspid regurgitation, a possible mechanism of tricuspid regurgitation is discussed in this patient.

Aged↗
PubMed1988

Cytophotometric DNA analysis of esophageal dysplasia and carcinoma induced in rats by N-methyl-N-amylnitrosamine.

A series of esophageal lesions, mild, moderate and severe dysplasia, carcinoma in situ (CIS), early and advanced squamous cell carcinoma were induced in rats with N-methyl-N-amylnitrosamine (MAN). To evaluate the biological nature of each lesion, the ploidy level was estimated by microspectrophotometrical measurement of cell nuclear DNA content. DNA distribution patterns were classified into types I, II, III and IV, according to the degree of dispersion and the peak modal value on the DNA histogram. The incidences of type III of high ploidy in early cancer, CIS and severe dysplasia were 3/11 (27.3%), 5/13 (33.3%) and 4/16 (25%), respectively. On the other hand, in moderate and mild dysplasia, 15/16 (93.8%) and 20/21 (95.2%) were low ploidy (types I and II), respectively. The mean DNA content of advanced and early cancer, CIS and severe dysplasia were 3.88c, 3.34c, 3.24c and 3.13c, respectively, while those of moderate and mild dysplasia were near diploid, showing 2.67c and 2.51c, respectively. These findings indicate that the biological nature of severe dysplasia may be considered as serious a lesion as cancer, in terms of DNA analysis. Cytophotometric DNA analysis aids the evaluation of various degrees of dysplasia and carcinoma of the esophagus.

Animals↗
PubMed1988

Suppression of exercise-induced angina by magnesium sulfate in patients with variant angina.

The effects of intravenous magnesium on exercise-induced angina were examined in 15 patients with variant angina and in 13 patients with stable effort angina and were compared with those of placebo. Symptom-limited bicycle exercise and thallium-201 myocardial scintigraphy were performed after intravenous administration of 0.27 mmol/kg body weight of magnesium sulfate and after placebo on different days. In all patients, serum magnesium levels after administration of magnesium sulfate were about twofold higher than levels after placebo. Exercise-induced angina associated with transient ST segment elevation occurred in 11 patients with variant angina receiving placebo and in only 2 of these patients receiving magnesium (p less than 0.005). On the other hand, exercise-induced angina was not suppressed by magnesium in any patient with stable effort angina. In these patients there was no significant difference in exercise duration after administration of placebo versus after administration of magnesium. The size of the perfusion defect as measured by thallium-201 scintigraphy was significantly less in patients with variant angina receiving magnesium than that in those receiving placebo (p less than 0.001), whereas it was not significantly different in patients with stable effort angina receiving placebo versus magnesium. In conclusion, exercise-induced angina is suppressed by intravenous magnesium in patients with variant angina but not in patients with stable effort angina. This beneficial effect of magnesium in patients with variant angina is most likely due to improvement of regional myocardial blood flow by suppression of coronary artery spasm.

Adult↗
PubMed1988

Defects in muscle fiber growth in fatal infantile cytochrome c oxidase deficiency.

In addition to numerous ragged-red fibers in the muscle from a female infant with fetal infantile cytochrome c oxidase deficiency, the muscle fibers were small in caliber with electron microscopic characteristics of immaturity; the satellite cells were significantly increased in number to 31.3% as compared with those in controls, 8.4 +/- 1.6% (p less than 0.001). In the culture system, the biopsied muscle showed markedly reduced growth despite the presence of numerous satellite cells which are known to act as myoblasts in muscle regeneration, and formed fewer numbers of myotubes containing poorly organized myofibrils and mitochondria with no cytochrome c oxidase activity. A defect in myogenesis and a paucity in repair process in severe form may account for the progressive course and a fatal outcome.

Biopsy↗
PubMed1988

High levels of heterodisperse RNAs accumulate in T cells infected with human immunodeficiency virus and in normal thymocytes.

Infection by human immunodeficiency virus (HIV-1) of a human T leukemia cell line (HUT 78) leads to a rapid accumulation at an elevated level (10- to 20-fold) of heterodisperse RNAs, revealed by their containing repetitive sequences. Sequence data indicate that the repetitive elements (e.g., Alu) are associated with transcripts with no apparent long open reading frame. In contrast, a large increase of such heterodisperse RNAs is not seen in T lymphocytes activated by phytohemagglutinin or in a variety of leukemic cell lines. Examination of several cellular messages showed that the levels of some of their "fully processed" transcripts are reduced late after infection of HUT 78 cells, indicating that the levels of some mRNAs may decrease. Surprisingly, similar heterodisperse transcripts are also seen in great abundance in normal fresh thymocytes. It is possible that in HIV-infected T lymphocytes, the accumulation of high levels of such aberrant RNAs may directly or indirectly contribute to the death of HIV-infected T cells.

Base Sequence↗
PubMed1988

Molecular forms of atrial natriuretic peptide in the atrium of patients with cardiovascular disease.

To determine the molecular forms of atrial natriuretic peptide (ANP) in patients with cardiovascular disease, we analyzed the ANP content in the right atrium using reverse phase high performance liquid chromatography and RIA. Tissue from 35 patients, ranging in age from 1 month to 64 yr, was studied. The right atrial ANP content was high in patients with congestive heart failure regardless of age. We found three ANP components (alpha-, beta-, and gamma ANP), as previously found in tissue obtained at autopsy. In patients younger than 20 yr old, the major component was gamma ANP. In older patients, the frequency and content of the two low mol wt forms, especially beta ANP, were increased. The differences in the content and molecular forms of ANP in atrial tissue reflect the pathological state in patients with cardiovascular diseases, as well as the patient's age.

Adolescent↗
PubMed1988

Physiological significance of fetal blood gas changes elicited by different delivery postures.

We performed umbilical blood gas analysis for 130 pregnant women in sitting and for 50 in supine position immediately after their deliveries. To elucidate whether fetal blood gas changes were attributed to the maternal postures, we also carried out the maternal blood gas analysis during delivery (n = 145) and prior to the onset of labor (n = 100) in both positions. Blood gas values of the umbilical vein and artery in the sitting group were significantly higher in pH, PO2, base excess (BE) and oxygen saturation (SO2), and lower in PCO2 than those in the supine group. In contrast, maternal blood gas values (pH, PaCO2, PaO2 and SaO2) did not show significant differences between these two groups in both during delivery and before the onset of labor. Thus, the sitting delivery position can elicit physiologically more beneficial blood gas aspects in fetus compared with the conventional supine delivery position. Umbilical blood gas improvements induced by sitting delivery position do not appear to be a result of the maternal blood gas alteration, but appear to be mediated by other factors.

Carbon Dioxide↗
PubMed1988

[Carcinoembryonic antigen, alpha-fetoprotein and hepatoma alkaline phosphatase in gastric carcinoma].

Reported here is a 38-year-old woman who had a gastric cancer accompanied with liver metastasis. Abnormal serum levels of a carcinoembryonic antigen, alpha-fetoprotein, and an alkaline phosphatase isozyme were observed persistently after a gastrectomy. The properties of this alkaline phosphatase isoenzyme were identical to a hepatoma alkaline phosphatase type. Histologic findings of the stomach revealed a poorly differentiated adenocarcinoma. The patient died on the 180th postoperative day.

Adenocarcinoma↗
PubMed1988

Clinical application of a new vital staining method for the conduction system during heart operations.

A new method for vital staining of the conduction system during heart operations, the iodine gas method, was used in 12 patients. The right bundle branch stained well in all cases, and could be confirmed by the naked eye. The conduction system was not damaged by the staining procedure. The iodine gas used in this method had no adverse effects on thyroid function (thyroxine, triiodothyronine, thyroxine binding globulin, protein bound iodine) or liver function (serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, lactic dehydrogenase). This method, therefore, was found to be valuable and without complication for preventing conduction disturbances during cardiac operations.

Cardiac Surgical Procedures↗
PubMed1988

T lymphocytes emigrating from the thymus to the spleen during postpartum regulate serum immunoglobulin levels in mice.

We noted an increase of a splenic T-cell population in early postpartum normal mice, but not in thymectomized (Tx) postpartum mice. The T-cell population consisted mainly of Lyt-1+2- cells and exerted suppressive activity in in vitro assays. To determine the in vivo function of these emigrant T lymphocytes during postpartum, we investigated the effect on immunoglobulin levels in the sera of mice, from pregnancy through the postpartum stages. A reduction in serum IgG1 levels in the late postpartum period was subsequent to the transitory elevation of IgG1 levels in early postpartum. However, this reduction of IgG1 was not seen in Tx mice at the late postpartum stage. To confirm the relationship between emigrant T cells and the immunoglobulin level, an adoptive transfer experiment was done. The level of IgG1 was reduced in the sera of recipients to which enriched splenic T cells from 3-day postpartum mice had been transferred. The data from the adoptive transfer experiment provided evidence that the increased T-cell population in mice in the early postpartum period regulates the IgG1 level in the serum. It was also recognized that T lymphocytes with the Lyt-1+2-phenotype, which emigrated from the thymus to the spleen after delivery, were able to suppress the IgG1, IgG2a,IgG2b levels in the serum. In addition, the appearance of the suppressive function of the Lyt-1+2- cells in these IgG subclasses required co-operation with the Lyt-1-2+ cells. Therefore, the thymus-dependent emigrant cells in the periphery in early postpartum mice may play a significant role in controlling immunoglobulin levels in the serum.

Animals↗