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Biomedical subjects

H Imamura

Publications and source records attributed to H Imamura.

At least 289 records · Page 16Linked to original sources
PubMed1991

Effect of cardioplegic preservation on intracellular calcium transients.

Intracellular Ca2+ ([Ca2+]i) plays a pivotal role in the regulation of cardiac function. We investigated the effect of cardioplegic preservation on [Ca2+]i transients in the isolated and perfused guinea pig heart loaded with a fluorescent Ca2+ indicator (fura-2). The measurements of [Ca2+]i transients and isovolumetric left ventricular pressure revealed that [Ca2+]i transients and mechanical responses to [Ca2+]i were markedly altered during 15 minutes of normothermic global ischemia and after reperfusion. First, [Ca2+]i transients remained during ischemia without generation of active force of contraction. Such a manifestation of depressed sensitivity of the myofilaments to Ca2+ persisted for the first 5 minutes after reperfusion. Second, the amplitude of [Ca2+]i was diminished during ischemia and reperfusion. Third, diastolic [Ca2+]i was increased during ischemia and especially at the onset of reperfusion. Bolus infusion of cold St. Thomas' Hospital solution abolished [Ca2+]i transients and left ventricular pressure development at an end-diastolic level. Moreover, improved recovery of left ventricular function during reperfusion afforded by the hypothermic cardioplegia was intimately related to its ability to modulate impaired [Ca2+]i transients and mechanical responses to [Ca2+]i; improvement of systolic left ventricular function appears to be produced by restoration of Ca2+ sensitivity of the myofilaments and the amplitude of [Ca2+]i transients, whereas better diastolic compliance of the left ventricle is ascribed to significantly lower diastolic [Ca2+]i. These results may provide new insight into the mechanism of cardioplegic preservation on the basis of [Ca2+]i transients.

Animals↗
PubMed1991

Characterization of B cells in human thymus.

The surface characteristics of B cells present in the human thymus were investigated. Cytofluorometrical and immunohistological studies, using anti-human IgM or anti-B cell monoclonal antibodies (mAbs; anti-Leu 12Ab, anti-Leu 16Ab, or L26), revealed that a small number of B cells are present in the human thymus. The thymic B cells were detected only in a low-density cell population, whereas in a high-density cell fraction, only T cells were found. In 15 cases, all of which the thymi were histologically normal, the percentages of B cells in the low-density fraction were 0.28% to 50% (6.8% in average), and Leu 1+ (CD5+) B cells in the low-density fraction were 0.1% to 26% (3.5% in average); approximately 50% of the thymic B cells were Leu 1+ B cells. These results indicate that B cells, especially Leu 1 (CD5)+ B cells, are also present in the human thymus, as suggested from our previous reports on mice.

Adolescent↗
PubMed1991

Studies on glycolipids. III. Glyceroglycolipids from an axenically cultured cyanobacterium, Phormidium tenue.

Seven new monogalactosyl diacylglycerols (1-7) and six new digalactosyl diacylglycerols (11-16) were isolated from an axenically cultured cyanobacterium, P. tenue. Their structures were elucidated on the basis of physicochemical evidence and the results of enzymatic hydrolysis using a lipase (from Rhizopus arrhizus). Comparison of antialgal activity for P. tenue between monogalactosyl diacylglycerols (1-8) and digalactosyl diacylglycerols (11-19) revealed that the former showed more potent activity than the latter.

Cyanobacteria↗
PubMed1991

Effects of amiloride and an analogue on ventricular arrhythmias, contracture and cellular injury during reperfusion in isolated and perfused guinea pig heart.

The present study was designed to examine whether activation of Na+/H+ exchange and subsequent massive Ca2+ influx via Na+/Ca2+ exchange are involved in the pathogenesis of myocardial reperfusion injury. We tested the effects of 1 mM amiloride, which is known to inhibit both Na+/H+ and Na+/Ca2+ exchange, and 3 microM 5-(N-ethyl-N-isopropyl) amiloride (EIPA), which is known to act as a specific inhibitor against Na+/H+ exchange, on the incidence of ventricular arrhythmias, isovolumic left ventricular function and creatine kinase (CK) release during reperfusion after 15 or 30 min of global ischemia in the isolated and perfused guinea pig heart. Treatment of a normally perfused heart with amiloride decreased heart rate significantly and tended to increase coronary flow and left ventricular developed pressure (LVDP), whereas treatment with EIPA decreased all of these 3 measurements significantly. Treatment with amiloride or EIPA for 15 min before ischemia, and during reperfusion after 15 min of ischemia, under electrical pacing at 240 rpm to eliminate a negative chronotropic effect abolished ventricular tachycardia (VT) and ventricular fibrillation (VF) during reperfusion associated with highly significant inhibition of increases in left ventricular end-diastolic pressure (LVEDP) and CK release. Amiloride or EIPA pretreatment also inhibited the incidence of VF and increases in LVEDP and CK release significantly during reperfusion after 30 min of ischemia. However, amiloride was more effective in preventing these events than EIPA. The treatment with amiloride or EIPA only during reperfusion after 15 or 30 min of ischemia also decreased the incidence of VF and inhibited the increases in LVEDP and CK release significantly, though less effectively than the pretreatment modality. These results suggest that EIPA prevents ventricular arrhythmias, contracture and myocardial cellular injury during reperfusion after 15 min of ischemia by inhibiting Na+/H+ exchange, while amiloride exerts more powerful protection against these events than EIPA during reperfusion after 30 min of ischemia by inhibiting both Na+/H+ and Na+/Ca2+ exchange.

Amiloride↗
PubMed1991

Improvement in iron deficiency anemia through therapy with ferric ammonium citrate and vitamin C and the effects of aerobic exercise.

In 781 female college students, there were 41 cases of iron deficiency anemia, 209 of latent iron deficiency, 3 of other anemias, and 528 normal cases. Fifty-four volunteers recruited from the iron deficiency anemia and severe latent iron deficiency groups were randomly divided into 4 study groups. Groups I and III received 500 mg of vitamin C daily, and groups II and IV received ferric ammonium citrate (FeAC; equivalent to 6 mg iron) in addition to vitamin C for 9 weeks. Groups I and II were loaded by aerobic exercise at 50% VO2 max. Significant differences between groups were noted in serum ferritin (SF) in III/IV, hematocrit (Ht) in II/III and III/IV, and reticulocytes (RET) in I/II, I/IV, and III/IV. Hemoglobin (Hb) and other iron-related blood indices tended to normalize in groups II and IV when compared with the pre-values. VO2 max was elevated in groups I and II regardless of iron treatment, but was augmented more in group II than group I.

Adolescent↗
PubMed1991

[Retrospective clinical evaluation of prognosis factors in stage D2 prostatic cancer treated with endocrine therapy].

Of 91 patients with prostatic cancer treated at our Department of Urology, from January 1976 through December 1987, 42 cases of stage D2 cancer treated with endocrine therapy were evaluated retrospectively with regard to clinical parameters and prognoses. The patients with marked increase in the level of the prostatic acid phosphatase (PACP), and the lactate dehydrogenase (LDH) in serum, and marked decrease in volume of hemoglobin (Hb) had a poor prognosis. The patients who took a long time to obtain a favorable response to the therapy had a poor prognosis. The response grade in NPCP criteria at 3 months after the initiation of therapy reflected the prognosis, and showed good correlation to the grade of favorable response.

Acid Phosphatase↗
PubMed1991

Quantitative evaluation of parenchymal liver cell volume and total hepatocyte number in cirrhotic patients.

A simple morphometrical method was developed using a color image analyzing system, which allowed quantitative evaluation of parenchymal liver cell volume and total hepatocyte number in cirrhotic patients. With this method, we estimated these values in 29 cirrhotic patients who underwent hepatic resection (nine cases) or nonshunting operation (20 cases). Liver volume, calculated from computed tomographic images, was 976 +/- 196 cm3 (range = 602 to 1,376 cm3); the parenchymal cell volume ratio, obtained based on liver histological appearance with silver stain, was 0.665 +/- 0.092 (range = 0.510 to 0.881); and the parenchymal cell volume, calculated by multiplying the liver volume with the parenchymal cell volume ratio, was 645 +/- 140 cm3 (range = 403 to 936 cm3). The total hepatocyte number obtained in a similar manner using hematoxylin-stained specimens was 1.72 +/- 0.56 x 10(11) (range = 0.74 to 2.94 x 10(11)). The validity and applicability of the method is discussed, and the data are compared with those reported in other studies.

Cell Count↗
PubMed1991

[Experimental study on the determination of estrogen receptor and the effect of antiestrogen therapy in breast cancer].

Thirty-five patients with breast cancer were examined for estrogen receptor (ER) by biochemically and immunohistochemically, and sensitivity to antiestrogen agents was investigated experimentally in order to obtain strict indications for antiestrogen therapy. Biochemically, cytoplasmic and nuclear ER (ERc and ERn) were determined using the DCC method. Immunohistochemical assay of ER (ER-ICA) was carried out using the enzyme-labeled antibody method. Sensitivity to antiestrogen agents was determined by subrenal capsule assay (SRCA). 1. The positive rates were 63.0% for ERc, 40.7% for ERn, and 44.4% for ER-ICA. 2. Anti-estrogen therapy was effective in 64.7% of ERc-positive patients, 72.7% of ERn-positive patients, and 91.7% of ER-ICA-positive patients. 3. ER-ICA was negative in 83.3% of ERc-positive patients who did not respond to antiestrogen therapy. Both of the two patients who were negative for ERc and responded to antiestrogen therapy were ER-ICA-positive. Thus, it seems possible that indications for antiestrogen therapy can be specified more strictly than before, using the results of ER assay by the enzyme-labeled antibody method.

Adult↗
PubMed1991

[Stab wounds of the spinal cord by a kitchen knife: report of a case].

A case of spinal cord injury due to stab wounds by a kitchen knife is presented. A 41-year-old male was hospitalized because of spinal cord injury resulting from stab wounds inflicted with a kitchen knife in the posterior cervical area. Neurological examination on admission showed paraplegia, disappearance of deep tendon reflex in both lower extremities, sensory disturbance below T1 level, left Horner's syndrome and urinary disturbance. In addition to these symptoms cerebrospinal fluid was leaking from the wounds. An emergency operation was performed. After laminectomy of C7 and T1, we found that the spinal cord was almost completely split at C7/T1 level. Dural plasty was performed. Neurologically, sensory disturbance was slightly improved at 4 months after the injury. Initial MRI (TR: 200 msec, TE: 20 msec) revealed high intensity at C7/T1 level which was damaged by the kitchen knife. MRI 5 months after the injury revealed low intensity on T1 weighted imaged, high intensity on T2 and proton weighted image. The occurrence of the spinal cord injury due to stab wounds by a kitchen knife is very rare in Japan. MRI is useful in the diagnosis of stab wounds of the spinal cord.

Adult↗
PubMed1990

The mechanism of antifungal action of (S)-2-amino-4-oxo-5-hydroxypentanoic acid, RI-331: the inhibition of homoserine dehydrogenase in Saccharomyces cerevisiae.

We have explored the mechanism by which an antifungal antibiotic, (S)-2-amino-4-oxo-5-hydroxypentanoic acid, RI-331, preferentially inhibits protein biosynthesis in Saccharomyces cerevisiae, by inhibiting the biosynthesis of the aspartate family of amino acids, methionine, isoleucine and threonine. This inhibition was effected by inhibiting the biosynthesis of their common intermediate precursor homoserine. The target enzyme of RI-331 was homoserine dehydrogenase (EC.1.1.1.3) which is involved in converting aspartate semialdehyde to homoserine in the pathway from aspartate to homoserine. The enzyme is lacking in animals. So the antibiotic is selectively toxic to prototrophic fungi.

Alcohol Oxidoreductases↗
PubMed1990

Treatment of patients with disseminated intravascular coagulation by protein C.

The therapeutic effect of highly purified protein C (PC) or activated protein C (APC) on three patients with disseminated intravascular coagulation (DIC) was tested. In two out of three cases, although therapeutic dose of heparin was not effective, PC or APC administration significantly improved the hypercoagulable state. In one case with acute leukemia who developed DIC with the severe gastrointestinal bleeding, APC corrected the hypercoagulable state without aggravating bleeding. These findings suggested that PC and/or APC might be effective in correcting hypercoagulable state without any adverse effect.

Anticoagulants↗
PubMed1990

Aortopulmonary shunt with replacement of a common atrioventricular valve in a patient with double inlet ventricle.

Replacement of a common atrioventricular valve with a St. Jude medical prosthesis, together with construction of a central aortopulmonary shunt using a polytetrafluoroethylene graft, were performed on a patient with double inlet ventricle complicated by severe regurgitation across an atrioventricular valve and hypoplastic pulmonary arteries. No complications were noted during a postoperative follow-up of 58 months; indeed, a considerable increase was noted in postoperative exercise capacity. This simple surgical procedure should be considered as a mode of treatment in patients with this combination of lesions.

Blood Vessel Prosthesis↗
PubMed1990

Organic acid and acylcarnitine profiles of glutaric aciduria type I.

Urinary organic acid and acylcarnitine profiles from a 2-month-old boy were studied by gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry. The patient excreted large amounts of glutaric acid and significant amounts of 3-hydroxyglutaric acid, glutaconic acid and glutarylcarnitine, and his serum glutaric acid level was markedly elevated. Thus he was chemically diagnosed as having glutaric aciduria type I (GAI). In addition to the above metabolites previously described in GAI, significantly increased excretion of 2-ketoglutaric acid, succinic acid, adipic acid, adipylcarnitine, suberic acid and azelaic acid was found. 2-Ketoadipic acid methylsuccinic acid and ethylmalonic acid were also detectable, suberylcarnitine was not increased, and dehydroadipylcarnitine was decreased in his urine. These results suggest that excess glutaryl-CoA causes the competitive inhibition of the dehydrogenation of adipyl-CoA to dehydroadipyl-CoA and results in an increase of adipic acid and adipylcarnitine and a decrease of dehydroadipylcarnitine. It is also suggested that oxidative decarboxylation of 2-ketoglutaric acid to succinyl-CoA is inhibited by high levels of glutaryl-CoA, and that the dehydrogenation of succinic acid to fumaric acid is inhibited owing to the increased glutaric acid derived from excess glutaryl-CoA. These results indicate that gas chromatography-mass spectrometry is the most appropriate and accurate method for the differential chemical diagnosis of GAI and glutaric aciduria type II.

Acylation↗
PubMed1990

Inhibition of 125I organification and thyroid hormone release by interleukin-1, tumor necrosis factor-alpha, and interferon-gamma in human thyrocytes in suspension culture.

To elucidate the mechanism of decreased 131I uptake by the thyroid gland in patients with subacute thyroiditis and painless thyroiditis, human thyroid follicles were cultured with interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF alpha), and/or interferon-gamma (IFN gamma), and the effects of these cytokines on thyroid function were studied in vitro. When human thyrocytes were cultured in RPMI-1640 medium containing 0.5% fetal calf serum and TSH for 5-8 days, the cells incorporated 125I, synthesized de novo [125I]iodotyrosines and [125I]iodothyronines, and secreted [125I]T4 and [125I]T3 into the medium. IL-1 alpha and IL-1 beta inhibited 125I incorporation and [125I]iodothyronine release in a concentration-dependent manner. The minimal inhibitory effect was detected at 10 pg/ml. Electron microscopic examination revealed a marked decrease in lysosome formation in IL-1-treated thyrocytes. TNF alpha and IFN gamma also inhibited thyroid function in a concentration-dependent manner. Furthermore, when thyrocytes were cultured with IL-1, TNF alpha and IFN gamma, these cytokines more than additively inhibited thyroid function. Although the main mechanism of 131I uptake suppression in the thyroid gland in subacute thyroiditis is due to cellular damage and suppression of TSH release, our present findings suggest that IL-1, TNF alpha, and IFN gamma produced in the inflammatory process within the thyroid gland further inhibit iodine incorporation and at least partly account for the decreased 131I uptake by the thyroid gland in destruction-induced hyperthyroidism.

Cells, Cultured↗
PubMed1990

[Valve prostheses of mitral position in children].

Twenty children less than 15 years old of age who had undergone mitral (left-sided atrioventricular) valve replacement before August 1983 have been followed up until October 1988. Fourteen biological valves (B-group) and seventeen mechanical valves (M-group) were used in them. Preoperative conditions had been similar between B- and M-groups. For the B-group, there were one operative death and two late deaths. For the M-group there were no operative death and three late deaths. An actuarial survival rate at ten years was 53.5 +/- 23.3% for the B-group and 85.7 +/- 9.4% for the M-group (not significant). All biological valves were calcified and failed in 27 to 89 months. Three mechanical valves caused thrombosis. There was no other complication for both groups. An event free rate was 0% at eight years for the B-group, however it was 70.6 +/- 11.0% at ten years for the M-group (p less than 0.025). Our data indicates that the mechanical valve is more suitable than the biological valve for children.

Bioprosthesis↗
PubMed1990

[Study of conservative treatment of breast cancer in view of the spread of primary lesion].

Two hundred and six patients with breast cancer t1 or t2 were subclassified histologically into the following 8 types; comedo type, papillary type, mucous type, papillotubular or cribriform type, small solid alveolar type, large solid alveolar type, sclerotic type and pure scirrhous type. The risk of remaining cancer with lumpectomy was investigated clinicopathologically in relation to intraductal spread and lymphatic invasion of cancer cells. The tumor invasion was classified into intraductal type, localized type or extraductal spreading type, and lymphatic invasion was divided into 2 grades, i.e., vicinity of the tumor and 5mm or more distant. 1. In cases of intraductal spread, the comedo type was the most frequent, followed by the papillary type and mucous type. 2. The small solid alveolar type accounted for the highest proportion, 22.7%, in the group with distant lymphatic invasion. 3. The incidence of lymph node metastasis was as high as 63.6% and 61.7% for the small solid alveolar type and pure scirrhous type. 4. In cases of intraductal spread, t1 accounted for 32.6% and t2 for 47.0%. 5. The incidence of positive lymph node metastasis was 28.9% for t1 and 52.0% for t2. Tumors associated with a higher risk of remaining cancer are those of the comedo type and papillary type in terms of intraductal spread, those of the small solid alveolar type and pure scirrhous type in terms of lymphatic invasion, and those measuring 2cm or more.

Breast↗
PubMed1990

[Effects of intra-arterial infusion of degradable starch microspheres on liver tissue blood flow].

The effects of intra-arterial infusion of degradable starch microspheres (DSM) on liver tissue blood flow were estimated in rat with liver carcinoma induced by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) administration. Tissue blood flow of tumor and normal liver was measured simultaneously by Laser blood flowmeter. Tissue blood flow of tumor and normal liver was 13.3 +/- 6.9, 13.2 +/- 4.3 (ml/min/100 g), respectively. After intra-arterial infusion of DSM, tissue blood flow of both tumor and normal liver decreased to the same degree as that at hepatic artery occlusion and then gradually recovered. This gradual recovery of tissue blood flow was supposed to express the process of resolution of DSM by alpha-amylase. The recovery time of tissue blood flow following intra-arterial infusion of DSM was 27.3 +/- 4.0 min (DSM 20 mg/kg) and 70.0 +/- 23.6 min (DSM 30 mg/kg) in tumor and 20.0 +/- 3.3 min and 36.5 +/- 18.0 min, respectively, in normal liver. Thus, the blocking effect of blood flow by DSM was different between tumor and normal liver and proved to be more persistent in the former.

Animals↗