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Biomedical subjects

Y Koga

Publications and source records attributed to Y Koga.

At least 541 records · Page 30Linked to original sources
PubMed1985

[Dysfunction of Carpentier-Edwards porcine mitral bioprosthesis causing a musical systolic murmur: a report of two cases].

Two patients with disruption of Carpentier-Edwards porcine mitral bioprosthesis presenting with a musical systolic murmur were reported. The two patients noted sudden development of a loud musical murmur 4 (Case 1) and 6.5 (Case 2) years after surgery. Case 1 had associated heart failure. Phonocardiogram disclosed a loud musical systolic murmur with regular vibrations at 230-240 Hz in Case 1, and 250-260 Hz in Case 2. In Case 1, echocardiography demonstrated fine fluttering of the porcine mitral valve at the same frequency as the murmur. Doppler echocardiography revealed characteristic Doppler signals from the porcine valves at a frequency of 250-300 Hz with several harmonics above and below the baseline. In addition, in Case 2, similar Doppler signals were obtained from the aortic walls, ventricular septum and posterior wall of the left ventricle. In both cases, left ventriculograms demonstrated grade 3 mitral regurgitation without paravalvular leakage, and at surgery, the porcine bioprosthesis showed a tear in one of markedly thinned cusps, without evidence of calcification. It was considered that a torn cusp was the source of the murmur, and this, in association with the resonance of the entire heart, produced the loud musical murmur. Thus, a musical systolic murmur is suggested to be one of important signs of dysfunction of porcine bioprosthesis.

Adult↗
PubMed1985

Restoration of T-cell function and induction of antitumor immune response in T-cell-depressed spontaneously hypertensive rats by treatment with thymosin fraction 5.

We studied the effect of treatment with Thymosin Fraction 5 (Fr-5) on the restoration of T-cell functions and the induction of antitumor immunity in spontaneously hypertensive rats (SHR) with congenital T-cell depression. SHR showed a reduced number of rosette-forming thymocytes early in their lives, and in vitro incubation of SHR thymocytes with Fr-5 restored the numbers of rosette-forming T-cells to the normal level for Wistar/HMK rats, the original strain of SHR. In vivo treatment of SHR with various doses of Fr-5 (0.5, 1.0, or 2.0 mg/kg, 6 times every other day) also increased significantly the blastogenic responses of their spleen cells to phytohemagglutinin but failed to promote plaque-forming cell responses to sheep red blood cells. These immunological restorative effects by Fr-5 were dose dependent. In contrast, treatment with lower doses of Fr-5 (0.25 or 0.50 mg/kg) showed greater curative effects on a high antigenic fibrosarcoma (SMT-6) than did treatment with higher doses of Fr-5 (1.0 or 2.0 mg/kg). This was confirmed by the fact that treatment with a 0.5-mg/kg dose of Fr-5 caused a significant suppressive effect on the growth of a weakly antigenic and highly metastatic adenocarcinoma (SST-2) in SHR with a consequent prolongation of survival days, whereas treatment with a 1.0- or 2.0-mg/kg dose of Fr-5 was without any effect. In order to clarify this mechanism, we studied the effect of pretreatment with cyclophosphamide (CY) on the development of antitumor delayed-type hypersensitivity (DTH) reaction in the SMT-6-bearing SHR treated with Fr-5 (0.5 or 2.0 mg/kg). Treatment with 0.5 mg of Fr-5 per kg significantly increased the DTH reaction to SMT-6 cells in both CY-pretreated and untreated SHR. In contrast, treatment with 2.0 mg of Fr-5 per kg produced a significant antitumor DTH reaction in SHR pretreated with CY but failed to induce the DTH reaction in SHR untreated with CY. These results suggest that higher doses of Fr-5 may induce preferentially suppressor T-cells rather than killer T-cells in tumor-bearing SHR with congenital T-cell depression.

Animals↗
PubMed1985

[Quantitative assessments of regional myocardial perfusion by digital subtraction angiography].

Regional myocardial perfusion was evaluated by computerized washout analysis of digital subtraction angiography (DSA) images. Diatrizoate meglumine (76% Urografin), 2 to 3 ml, was manually injected into the left main coronary artery. For 26 patients with ischemic heart disease (IHD), 14 patients with cardiomyopathy, and eight patients with normal coronary angiograms, DSA images of myocardial perfusions were obtained in the right anterior oblique projection. These were digitized into an image-processing computer. Time-density curves were constructed in four segments of the left ventricle perfused by the left anterior descending coronary artery (LAD) and the contrast decay half-lives (T1/2) were calculated from the decay phases of the curves, using mono-exponential least square fits. The mean T1/2 was significantly longer in patients with 75% or more LAD narrowing than in those with normal coronary arteries. By contrast, patients with 50% or less LAD narrowing had T1/2 comparable to those with normal coronary arteries. In patients with IHD, there was a significant curvilinear relationship of T1/2 with percent stenosis of the LAD. This indicates that a decrease in regional myocardial flow develops rapidly in coronary stenosis of 70-80% or more. In patients with comparable coronary stenosis, T1/2 was significantly longer in the asynergic regions than in those with normal wall motion, but T1/2 was shorter in regions perfused by collateral vessels. These findings indicate that left ventricular contraction and collateral flow could contribute to regional myocardial perfusion. In addition, patients with hypertrophic and dilated cardiomyopathy had prolonged T1/2 despite normal coronary angiograms, suggesting abnormalities in intramural coronary arteries. Thus, T1/2 derived by computerized washout analysis of DSA myocardial image proved to be a useful index for quantitative evaluation of regional myocardial perfusion.

Adult↗
PubMed1985

[Apical hypertrophy and its genetic and acquired factors].

Although apical hypertrophy is characterized by a spade-like configuration of the left ventricle and giant negative T waves on electrocardiograms, the identity of apical hypertrophy in the disease spectrum of hypertrophic cardiomyopathy (HCM) is not fully established. The present study compared the demography, familial occurrence, and acquired factors of 43 patients who had apical hypertrophy with those of 104 patients who had asymmetric septal hypertrophy (ASH). Demographically, apical hypertrophy occurred predominantly in middle-aged males (86%). Family surveys showed that 13% of siblings of apical hypertrophy were affected, significantly less than in obstructive (31%) or non-obstructive (29%) HCM with ASH. Thirty-eight percent of siblings of ASH patients less than 35 years of age were affected, with a male/female ratio of 4/5, suggesting an autosomal dominant inheritance. The acquired factors associated with apical hypertrophy were assessed in a case-control study. Relative risk (odds ratio) of the condition was 3.46 (p less than 0.05) in those with histories of hypertension, and increased further to 8.09 (p less than 0.001) in those who were often hypertensive according to their physician's evaluations. Thus a strong association of hypertension with apical hypertrophy was suggested. However, hypertension in this condition was usually mild and labile, the blood pressure reverted to the normal range within several days of hospital admission, implying that transient hypertension during daily activity is associated with apical hypertrophy. Therefore, blood pressure response during exercise stress tests of 25 patients with apical hypertrophy was compared with that of age- and sex-matched controls. Slopes of linear regression between systolic blood pressure and heart rate and oxygen consumption during exercise, were used as indices of blood pressure response. They were significantly greater in apical hypertrophy than in the controls (1.2 +/- 0.4 vs 0.9 +/- 0.3, p less than 0.01 and 4.3 +/- 1.7 vs 2.8 +/- 0.8, p less than 0.001). This trend was observed even in patients without histories of hypertension. These findings suggested that apical hypertrophy has an inheritance pattern different from that of ASH, and has a possible association with acquired factors such as hypertension. Therefore, apical hypertrophy seemed to be a disease entity distinct from HCM with ASH, though it might be included in the disease spectrum of HCM.

Adult↗
PubMed1985

[The effects of intra-abdominal pressure on regional renal blood flow during peritoneal dialysis].

This experimental studies were designed to investigate the effects of intra-abdominal pressure (IAP) on renal regional blood flow and renal function during peritoneal dialysis (PD) for acute renal failure (ARF). The mongrel dogs were divided into four groups. Group I (n = 10): IAP of atmospheric pressure without PD (control group); Group II (n = 10): Intermittent PD with IAP of 10 mmHg; Group III (n = 10): Intermittent PD with IAP of 20 mmHg; Group IV (n = 10): Continuous PD with IAP of 3-5 mmHg. The following results were obtained. Significant decrease (p less than 0.01-0.05) of renal cortical blood flow (RCBF), total renal blood flow (TRBF), ratio of RCBF to renal medullar blood flow, renal perfusion pressure (RPP), cardiac index and urinary output, and increased renal vascular resistance and inferior vena caval pressure were observed in group III, but in group IV, values of these parameters returned to control level. The limit of influence to renal function was confirmed to be as follows. (1) IAP of 30 mmHg or more, (2) RPP of less than 65 mmHg, (3) TRBF of less than 2.2 ml/g/min, (4) and RCBF of less than 78 ml/100 g/min. These studies suggest that RPP are simple and excellent index to reflex renal hemodynamics, and the continuous PD are better procedure than the intermittent PD from a view of renal regional blood flow.

Abdomen↗
PubMed1984

Products of phosphatidylglycerol turnover in two Bacillus strains with and without lipoteichoic acid in the cells.

In order to understand the phosphatidylglycerol turnover mechanism, especially the differential turnover of diacylated and unacylated glycerol moieties of the lipid, products of phosphatidylglycerol metabolism were surveyed in vivo in Bacillus subtilis W23 and an alkalophile, Bacillus sp. strain A007. When cells of B. subtilis W23 labeled with radioactive glycerol were chased, lipoteichoic acid accumulated 90% of the radioactivity lost from the unacylated glycerol moiety of phosphatidylglycerol. Also, lipids other that phosphatidylglycerol, except diacylglycerol, and glycerol and glycerophosphate incorporated much less radioactivity. The [32P]phosphoryl group was also transferred from phosphatidylglycerol to lipoteichoic acid almost quantitatively in B. subtilis W23. A unique metabolism of phosphatidylglycerol was found in Bacillus sp. strain A007 which lacked phosphoglycolipid and lipoteichoic acid, that is, the turnover of phosphatidylglycerol of this organism was less extensive compared with that of B. subtilis W23, and both glycerol moieties of the lipid were metabolized at an identical rate. These results suggested that the major reaction involved in the turnover of phosphatidylglycerol was the transfer of glycerophosphate residue to lipoteichoic acid in a bacterium which possessed lipoteichoic acid and that several minor reactions also were involved in phosphatidylglycerol turnover.

Bacillus↗
PubMed1984

Prognosis in hypertrophic cardiomyopathy.

One hundred thirty-six patients with hypertrophic cardiomyopathy were followed up for 1 to 17 years. Twenty-one patients had died, 14 of them suddenly, two from heart failure, two from cerebral embolism, and three from noncardiac causes. Life table analysis revealed that sudden death was significantly associated with young age less than 20 years (relative risk [rr] = 8.63, when compared with those greater than 40 years) and with positive Master's single two-step test (rr = 3.55). Heart failure was more frequent in patients with positive Master's single test (rr = 4.27) and with left ventricular end-diastolic pressure greater than 20 mm Hg (rr = 2.58). Atrial fibrillation, observed in 15 patients, was a poor prognostic sign, resulting in five cardiac deaths and seven heart failures. In contrast, prognosis was favorable in patients with apical hypertrophy with giant negative T wave. Thus Japanese patients with hypertrophic cardiomyopathy showed a prognosis consistent with Western patients, except for excellent outcome of apical hypertrophy.

Adult↗
PubMed1984

Recent trend on the prevalence of tardive dyskinesia in Japan.

An epidemiological study was undertaken, taking a survey of 2,274 chronic schizophrenic patients hospitalized for 2 years or more in 17 mental institutions in Japan. The overall prevalence of tardive dyskinesia (T.D.) was 19.1%. The prevalence of TD differs considerably from one institution to the other, with a range of 0 to 36.1%. The longer the history of institution was, the higher the prevalence of TD. The prevalence showed a tendency to increase with increasing age. Long-term hospitalization concomitant with continuous neuroleptic medication seemed to play a role in the prevalence of TD. TD occurred with higher frequency in patients with somatic complications than in those without complications. Past drug history, including duration of treatment and responsible neuroleptics, has been considered to play an important role in the prevalence of TD. But, results of the present investigation showed that the present drug status might also influence on the appearance of TD. The facts obtained from the present study are of value to establish regimens mainly based on medical treatment for prediction and prevention of TD.

Adult↗
PubMed1984

T-cell recruitment regulated by prostaglandin-mediated system and its role in immune response.

The dynamics of the number of T cells in spleen and the level of prostaglandin E2 in plasma were investigated serially in mice injected with Corynebacterium parvum. In the first few days, the level of plasma PGE2 increased but decreased to lower than the normal level thereafter. The absolute number of T cells in the spleen began to increase after the PGE2 level dropped. But such an increase of T cells was not observed in ATx mice challenged with C. parvum. Moreover, replenishing the mice with exogenous PGE2 in the period of low PGE2 halted selectively the increase of T cells in the spleen. This enlarged T cell subset responded to PHA, expressed Lyt-1+2+, and was sensitive to PGE2. And this T-cell subpopulation exerted a suppressive effect on antibody response in low PG environment, but lost its inhibitory effect in high PG milieu. These results suggested that an immature T cell subset is recruited from the thymus in a low PG state and participates as regulator cells in immune response at peripheral lymphoid organs.

Animals↗
PubMed1984

Thymus-recruited peritoneal exudate T lymphocytes.

The role of the thymus in the generation of antigen-reactive peritoneal exudate T lymphocytes (PETLs) was examined in mice injected with Corynebacterium parvum (C. parvum), which exerted functions as a trigger of T cell recruitment from the thymus and as an antigen to induce antigen-reactive T cells. The proliferative response of antigen-reactive PETLs was higher in sham mice than in adult-thymectomized (ATx) mice 3 weeks after injection of C. parvum. When indomethacin (INDO) was injected simultaneously with an injection of proteose peptone for collecting PETLs, the response to C. parvum decreased to an undetectable level in ATx mice, and to a low but still positive level in sham mice. The addition of PGE2 to the culture suppressed the proliferative response of PETLs from Sham mice, but did not suppress the response of ATx mice. These results suggested the existence of different subsets in antigen-reactive T cells in terms of thymus-dependency and PGE2-dependency or -sensitivity.

Animals↗
PubMed1984

Lens subluxation in homocystinuria. A case report.

A 6-year-old girl had bilaterally subluxated lenses and liver and platelet dysfunctions. A cyanide-nitroprusside test of the urine was positive. Serum and urinary levels of methionine and homocystine were high. Cystathionine synthetase activity in the cultured skin fibroblasts was negligible. Pyridoxine, 1000 mg/day orally, normalized the serum and urinary methionine and homocystine levels and the liver and platelet functions. Episodes of pupillary block glaucoma prompted lens extraction. The subluxated lenses were extracted under general anaesthesia after administration of pyridoxine and dextran to avoid thrombosis. A good result without serious complications was obtained. We believe that homocystinuria should not be considered a contra-indication to general anaesthesia. In the pyridoxine-responsive patient general anaesthesia is not hazardous if platelet function can be controlled by the vitamin.

Anesthesia, General↗