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Biomedical subjects

M Tani

Publications and source records attributed to M Tani.

At least 217 records · Page 12Linked to original sources
PubMed1994

Cardiac pheochromocytoma. A case report and review of the literature.

A case of intrapericardial pheochromocytoma which secreted predominantly norepinephrine is reported. A tumor at the posterior wall of the left atrium was demonstrated by computed tomographic and magnetic resonance imaging scan. Tumor blush arising from the left circumflex branch was visualized by coronary angiography. The tumor (4 x 3.5 x 2 cm) was resected with adherent atrial wall and the defect reconstructed with the patients own pericardium under general anesthesia with artificial cardiopulmonary bypass. His subsequent postoperative recovery was uneventful. At the time of discharge, 8 weeks after operation, his blood pressure and plasma norepinephrine remained normal. The value of magnetic resonance imaging scan for the topographic diagnosis of cardiac pheochromocytoma is emphasized.

Adult↗
PubMed1994

[Changes in electrocardiographic findings with aging in a longitudinal study of 500 apparently healthy persons aged 60 years and older].

A number of studies have been published which have attempted to define the electrocardiographic (ECG) changes with aging, but most of them were obtained from cross-sectional studies. To distinguish ECG changes related to physiological aging from those associated with arteriosclerosis, we assessed the ECG changes of 500 apparently healthy subjects, aged 60 years and older in 1992, who had been followed at the Keio Health Consulting Center for over 15 years. All subjects had no overt cardiovascular diseases in 1992. We compared the ECG in 1992 with that taken over 15 years ago. Changes in ECG during that period were also reviewed. With aging, the mean axis deviated to the left, the mean QTc interval was shortened, and the mean PR interval was prolonged. ST segmental change, atrial overloading, bundle branch block developed newly in 16%, 8% and 7% of, respectively. There were no relationships among axis deviation, PR interval change, or QTc shortening and coronary risk factors. QTc prolongation and ST segmental change were strongly related to hypertension or impaired glucose tolerance. When ECG changes in those under 65 years old were compared with those over 80 years old, the incidence of ST segmental change in those over 80 years old was significant higher. This study was not a prospective study but suggested each type of ECG change related to aging was affected by physiological and/or pathological factors in a distinct way and had different phases of development and progression.

Aged↗
PubMed1994

Electrophysiologic effects of intravenous E-4031, a novel class III antiarrhythmic agent, in patients with supraventricular tachyarrhythmias.

The electrophysiologic effects of intravenous (i.v.) E-4031, a new class III antiarrhythmic drug, were evaluated in 15 patients with supraventricular tachyarrhythmias [11 men, 4 women; mean age 41 +/- 19 (SD) years]. Eleven patients had accessory atrioventricular (AV) pathways, and 4 patients with no accessory pathway had paroxysmal atrial fibrillation. Electrophysiologic studies were performed before and after E-4031 administration (loading infusion 9 micrograms/kg for 5 min + maintenance infusion 0.15 microgram/kg/min). QT and QTc intervals were significantly prolonged by E-4031 from 0.40 +/- 0.03 (mean +/- SD) to 0.46 +/- 0.03 s (p < 0.0001) and from 0.43 +/- 0.03 to 0.49 +/- 0.04 s (p < 0.0001), respectively. No effect was observed on RR interval, PR interval, QRS duration, or AH and HV intervals. The effective refractory periods (ERPs) of the right atrium and ventricle were significantly prolonged from 219 +/- 27 to 236 +/- 26 ms (p < 0.001) and from 230 +/- 12 to 249 +/- 11 ms (p < 0.001), respectively. The ERP of the AV node did not change significantly after E-4031 administration. In patients with ventricular preexcitation, E-4031 significantly prolonged the ERP of the antegrade accessory pathway conduction from 340 +/- 101 to 362 +/- 106 ms (p < 0.001), but not retrograde accessory pathway conduction. AV reentrant tachycardia was induced in 3 of 11 patients with an accessory pathway, and repetitive atrial firing was induced in 3 of 4 patients with paroxysmal atrial fibrillation. E-4031 could prevent repetitive atrial firing in only 1 patient and could not prevent induction of AV reentrant tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Electronmicroscopic study on the vitreous membrane of the Stickler syndrome].

The vitreous membrane obtained from a patient with Stickler syndrome, an 8 year-old female, was investigated electronmicroscopically. The cells found in the membrane had cilia, microvilli and cytoplasmic filaments. Gap junctions and basement membrane-like structures were also found. Several of the cells had phagosomes containing crystalline materials. Thus, these cells seemed to be glial cells.

Abnormalities, Multiple↗
PubMed1994

Interspecies differences in enantioselective mono-N-dealkylation of disopyramide by human and mouse liver microsomes.

The interspecies differences in the enantioselective metabolism of disopyramide (DP) were studied with human and mouse liver microsomes. Mono-N-dealkylation of both DP enantiomers was biphasic, suggesting an involvement of two enzymes in the metabolism in both species. The human data indicated that the metabolism of both DP enantiomers at the therapeutic concentrations (i.e., 5-14 microM) was mediated by the high-affinity components. The mean (+/- S.D.) affinity constant (Km) of the high-affinity component for S-(+)-DP (4.86 +/- 2.66 microM) was significantly (P < .05) lower than that for R-(-)-DP (24.61 +/- 17.52 microM), whereas no difference was observed between the maximum velocities (Vmax) for S-(+)- and R-(-)-DP. The mean intrinsic clearance (CL(int)), defined as Vmax/Km, of the high-affinity component for S-(+)-DP was significantly greater (P < .01) than that for R-(-)-DP, consistent with the reported in vivo pharmacokinetic data. In contrast, the CL(int) of the low-affinity component for R-(-)-DP was significantly (P < .01) greater than that for S-(+)-DP. Coincubation of DP enantiomers as a racemate showed mutual competitive inhibition. With mouse liver microsomes, a preferential metabolism of S-(+)-DP over R-(-)-DP was also observed only for the high-affinity components. Although the mean Vmax for the high-affinity component of mouse microsomes was about 6- to 8-fold greater than that of human's, the differences in Km were at most 2.5-fold. In addition, metabolic competition between the enantiomers also occurred with mouse microsomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Effect of recombinant atrial natriuretic peptide (r-ANP) on ischemic and cyclosporine-induced kidney damage in rats].

Cyclosporine A (CYA) a new immunosuppressive drug, has greatly improved the outcome of solid graft transplantation. The nephrotoxicity of CYA, however, is a serious problem, and constitutes the major obstacle limiting the use of CYA as an immunosuppressive agent for renal transplantation. On the other hand, the newly described atrial natriuretic peptide (ANP) hormonal system in both humans and animals appears to play an important role in sodium and water excretion. The present study examined the nephrotoxicity of CYA and the effect of recombinant-ANP (r-ANP) on the damaged kidneys in three groups. Group 1 consisted of rats with 45 minutes warm ischemic left kidney and right nephrectomy [WI rats]; Group 2 consisted of WI rats with oral administration of CYA (100mg/kg/day) for 2 weeks [WI+CYA rats]; Group 3 consisted of WI+CYA rats with intraperitoneal administration of r-ANP (10ng/kg/day) for 2 weeks. Group 2 had lower glomerular filtration rates (GFR) and renal plasma flow (RPF) than Group 1, but Group 3 had significantly higher GFR and RPF than Group 2. Additionally, in order to demonstrate the change in renal viability among the three groups, the adenosine triphosphoric acid level (ATP) and adenylate energy charge ratio (EC) of renal parenchymal tissue were measured by high performance liquid chromatography (HPLC). Group 2 had lower ATP and EC than Group 1, and Group 3 had higher ATP and EC than Group 2. The results of this study suggest that r-ANP is efficacious on rat kidney damage induced by CYA and WIT.

Animals↗
PubMed1993

Astrocyte expression of mRNA encoding cytokines IP-10 and JE/MCP-1 in experimental autoimmune encephalomyelitis.

Mononuclear leukocytes preferentially accumulate in the central nervous system (CNS) during the course of experimental autoimmune encephalomyelitis (EAE). To address factors that govern leukocyte trafficking in EAE, we monitored expression of mRNAs encoding IP-10 and JE/MCP-1, which are members of a family of chemoattractant cytokines. A transient burst of IP-10 and JE/MCP-1 mRNA accumulation in the CNS occurred, in close relation to the onset of histologic and clinical disease. In situ hybridizations showed, unexpectedly, that astrocytes were the major source of mRNAs encoding IP-10 and JE/MCP-1. These observations implicate astrocyte-derived cytokines as potential chemoattractants for inflammatory cells during EAE.

Animals↗
PubMed1993

Expression of carcinoembryonic antigen in fresh human gastric cancer cells assessed by flow cytometry.

The expression of carcinoembryonic antigen (CEA) by tumor cells from freshly excised human gastric cancers was investigated using flow cytometry (FCM). Highly purified fresh human cancer cells were obtained from solid tumors in 20 patients and from malignant ascites in 6 patients. Thirteen of the 26 tumors were positive for CEA by FCM. CEA expression was more common in well-differentiated tumors than in poorly differentiated tumors. CEA expression was investigated by both FCM and immunohistochemistry in 9 patients, and the two methods agreed in 8 of them. However, quantitative evaluation of CEA expression could only be performed by FCM and not by immunohistochemical staining. FCM could analyze the expression of CEA not only on the cell membrane but also in the cytoplasm, by using gastric cancer cells with or without Triton X-100 treatment. Thus, this study showed that CEA expression can be determined and evaluated quantitatively by FCM.

Aged↗
PubMed1993

Development and preliminary application of a simple assay of S-mephenytoin 4-hydroxylase activity in human liver microsomes.

We have developed a simple HPLC assay to measure the activity of S-mephenytoin 4-hydroxylase in human liver microsomes, and have assessed its practical applicability by determining the kinetic parameters of the enzyme in 10 different human liver samples. The recovery of 4-hydroxymephenytoin and phenobarbital (the internal standard) after the precipitation of microsomal protein was almost complete, and the coefficients of variation for the intra- and interassay measurement of S-mephenytoin 4-hydroxylase activity were < 6.4 and 8.0%, respectively. Eadie-Hofstee plots for the formation of 4-hydroxymephenytoin gave a straight line for all of the 10 samples studied. There was large interindividual variability in the kinetic parameters estimated: 4.6- (36 to 166 microM), 11.8- (0.9 to 10.6 nmole/mg protein/h) and 30.1- times (0.10 to 3.01 microliters/mg protein/min) for Km, Vmax and Vmax/Km, respectively. The mean (+/- SD) Km, Vmax and Vmax/Km were 72.4 +/- 40.4 microM, 4.23 +/- 2.88 nmole/mg protein/h and 1.33 +/- 1.02 microliters/mg protein/min, respectively. Thus, the assay was sufficiently accurate and reproducible to permit estimation of the kinetic parameters of S-mephenytoin 4-hydroxylase in human liver microsomes, and it appears to be applicable to an in vitro study of the possible involvement of S-mephenytoin-type oxidation polymorphism in drug metabolism.

Aryl Hydrocarbon Hydroxylases↗
PubMed1993

Effects of diltiazem on concealed atrioventricular nodal conduction in relation to ventricular response during atrial fibrillation in anesthetized dogs.

By means of a new quantitative index for concealed conduction, we evaluated the effects of diltiazem on atrioventricular (AV) node concealment and correlated this index with the variability of the ventricular response during atrial fibrillation in 16 anesthetized mongrel dogs. After determination of the atrial effective refractory period (ERP), AV nodal ERP (AVNERP), concealment zone, and concealment index (AVNERP of blocked atrial extrasystole/AVNERP of conducted atrial extrasystole), the R-R intervals during atrial fibrillation induced by electrical stimulation were measured. Both low (0.1 mg/kg) and medium (0.2 to 0.4 mg/kg) doses of diltiazem prolonged the AVNERP and increased the mean R-R interval during atrial fibrillation. Only medium doses of diltiazem increased the degree of concealed conduction in the AV node and accentuated the variability of R-R intervals. There was a good positive correlation between the variability of the ventricular response during atrial fibrillation and the concealment index. In conclusion, medium doses of diltiazem are more effective in reducing heart rate during atrial fibrillation than a low dose. However, medium doses also increase the degree of concealed conduction in the AV node and enhance the irregularity of the ventricular response during atrial fibrillation. Measurement of the concealment index is useful for quantitating the degree of concealed conduction in the AV node, which is actually an important determinant of the ventricular response during atrial fibrillation.

Animals↗
PubMed1993

Effect of prostaglandins I2 (prostacyclin) and F2 alpha on function, energy metabolism, and calcium uptake in ischaemic/reperfused hearts.

OBJECTIVE: The aim was to examine the effect on cardiac function, energy metabolism, and calcium uptake of either prostaglandin I2 (PGI2, prostacyclin) or prostaglandin F2 alpha (both 28.6 nM) on the response of isolated rat hearts to 25 min of total global ischaemia with or without 30 min reperfusion. METHODS: Rat hearts were perfused by the Langendorff method and function assessed by left ventricular pressure. Energy metabolites were measured using enzymatic techniques and 45Ca2+ uptake determined by radioisotopic analysis. RESULTS: Although there was no effect of either prostaglandin on contractile depression during ischaemia, both compounds accelerated the onset of and increased the magnitude of ischaemic contracture. High energy phosphate content at the end of the ischaemic period was not affected by prostaglandin treatment; however, tissue lactate levels were increased by PGI2 as was tissue calcium content. Under control conditions mean recovery of left ventricular developed pressure ranged from 66% to 83%. In the presence of PGI2 and PGF2 alpha, recovery of developed pressure was reduced to 20% and 38% of preischaemic values, respectively. The reduced recovery in developed pressure was accompanied by an approximately threefold increase in diastolic pressure (p < 0.05). The depression of functional recovery in reperfused hearts treated with prostaglandins was associated with various disturbances of cellular metabolism including depressed ATP and creatine phosphate content and increased tissue lactate and calcium following 30 min of reperfusion. A significant correlation was found between the changes in developed pressure and diastolic pressure during reperfusion and the reduction in ATP and creatine phosphate repletion. The deficit in recovery of ventricular function also correlated significantly with increased lactate and calcium accumulation in the reperfused heart. CONCLUSIONS: Low concentrations of PGI2 and PGF2 alpha can depress contractile recovery of the globally ischaemic heart through a mechanism associated with altered cellular energy metabolism and increased calcium accumulation.

Adenosine Triphosphate↗
PubMed1993

Inhibition of glycolysis or increased perfusate H+ buffering capacity, but not their combination, attenuates myocardial stunning.

OBJECTIVE: Both inhibition of glycolysis and enhancement of the H+ buffering capacity of the perfusate during ischaemia reduce myocardial reperfusion injury. The aim of the study was to investigate whether these manoeuvres, performed separately or together, could reduce myocardial stunning after brief global ischaemia. METHODS: The hearts of male Sprague-Dawley rats were preperfused for 10 min with oxygenated or hypoxic buffer (pH 7.4) containing 100 mM sucrose, 100 mM HEPES, or 5 mM 2-deoxyglucose plus 100 mM sucrose, followed by 15 min of total ischaemia and 30 min of reperfusion. In some hearts, 5 mM 2-deoxyglucose was combined with 100 mM HEPES during the 10 min preperfusion period. RESULTS: Brief hypoxic preperfusion, 2-deoxyglucose, or HEPES reduced myocardial stunning as well as improving the metabolic recovery and reducing Ca2+ overload after reperfusion. These changes were associated with a smaller increase in intracellular Na+ and a smaller decrease of coronary effluent pH at the end of ischaemia. In contrast, the combination of HEPES with hypoxic preperfusion or 2-deoxyglucose depressed functional recovery and increased the intracellular Na+ level at the end of ischaemia as well as increasing Ca2+ overload after reperfusion. This happened even though the decrease in coronary effluent pH was attenuated to the same extent as before. CONCLUSIONS: Both inhibition of glycolysis and enhancement of the perfusate H+ buffering capacity before ischaemia attenuated myocardial stunning, but the protective effect of each manoeuvre was lost when they were combined.

Animals↗
PubMed1993

Sequential changes in sympatho-neuronal regulation and contractile function following aortic regurgitation in rabbit heart.

This study was designed to determine the sequential changes in sympatho-neuronal regulation and contractile function of hearts exposed to volume overloading. Aortic regurgitation was produced by perforation of the aortic valve in 20 rabbits. Another 20 rabbits underwent sham operation. They were randomly assigned to a 1-day group, a 1-week group, and a 4-week group. Haemodynamics, myocardial beta-adrenoceptor binding number and catecholamines were measured in each period after production of aortic regurgitation. Left ventricular end-diastolic pressure increased and cardiac output decreased progressively over the week following production of aortic regurgitation, but they returned towards normal during the subsequent 3 weeks. Left ventricular free wall thickness increased 4 weeks after production of aortic regurgitation, and plasma norepinephrine increased 1 day after the procedure. Maximal binding sites of myocardial beta-adrenoceptors (125I-iodocyanopindolol) were decreased 1 day and 1 week after production of aortic regurgitation. Myocardial norepinephrine was also reduced. After 4 weeks, both beta-adrenoceptor binding sites and myocardial norepinephrine content were restored. Alterations in sympatho-neuronal regulation are related to the compensatory processes in volume overloaded hearts.

Animals↗
PubMed1993

Effects of acute ischemia on anisotropic conduction in canine ventricular muscle.

The effects of acute ischemia on conduction velocities in the longitudinal (theta L) and transverse (theta T) fiber axis were determined from epicardial activation patterns, recorded with 48 bipolar electrodes (plaque electrode, 25 x 35 mm) on the left anterior ventricular wall of eight dogs and the posterior wall of seven dogs. During left ventricular stimulation (cycle length = 300 msec) in the center of the plaque electrode, theta L, theta T, and the ratio of longitudinal to transverse conduction velocities (theta L/T) were measured before and 2 to 5 minutes after occlusion of the left anterior descending coronary artery or the left circumflex coronary artery. During the control state theta L was greater than theta T demonstrating anisotropic properties of cardiac muscle, not only in the anterior but also in the posterior wall. During acute ischemia theta L and theta T were decreased from the control value and theta T was decreased by a greater extent than theta L resulting in an increase in theta L/T from 1.83 +/- 0.31 (mean +/- SD) to 2.19 +/- 0.36 in the anterior wall and from 1.58 +/- 0.17 to 1.92 +/- 0.28 in the posterior wall. During ventricular fibrillation some lines of conduction block were parallel to the long axis of epicardial muscle fiber bundle and the others were perpendicular. In conclusion, acute ischemia increased anisotropic conduction (theta L/T) in the epicardial ventricular muscle mainly due to greater reduction in theta T, in the anterior and the posterior wall. This augmented anisotropic ventricular conduction may have some relation to the initiation of ventricular fibrillation during acute ischemia.

Animals↗
PubMed1993

Attenuation of myocardial stunning by an increase in the H+ buffering capacity of the perfusate and that by hypoxic preperfusion are affected differently by the free [Ca2+] of the perfusate.

OBJECTIVES: Protons produced during ischemia may increase intracellular Na+ (Na+i) through Na+/H+ exchange, and may lead to Ca2+ overload through Na+/Ca2+ exchange to cause myocardial stunning. This study investigated whether an increase in the H+ buffering capacity of the perfusate or a reduction of H+ production by a brief hypoxic preperfusion before ischemia would reduce myocardial stunning. We also investigated whether the protective effect of these maneuvers depends on the free [Ca2+] of the perfusate. METHODS: Isolated rat hearts were preperfused with oxygenated or hypoxic buffer (pH 7.4) containing 100 mM of either sucrose or HEPES for 10 min, followed by 15 min of total ischemia and 30 min of reperfusion. To investigate the dependence of the effects of HEPES or a brief hypoxic preperfusion, the free Ca2+ concentration in the buffer was changed from 1.25 mM to 2.5 mM in some hearts. RESULTS: Oxygenated preperfusion with buffer containing HEPES and 1.25 or 2.5 mM Ca2+ improved the metabolic and functional recovery with a decrease in the accumulation of Na+i during ischemia and in 45Ca2+ uptake during reperfusion. A brief hypoxic preperfusion with 1.25 mM Ca2+ provided a similar protective effect whereas no protective effect was observed when the [Ca2+] was raised to 2.5 mM. CONCLUSIONS: An increase in the H+ buffering capacity or a brief hypoxic preperfusion reduced myocardial stunning with improved metabolic recovery, and reduced Ca2+ uptake. However, the effects of these interventions were affected differently by the free [Ca2+] of the perfusate, which suggests that they work, at least in part, through some different mechanism(s).

Animals↗
PubMed1993

[The changes in physico-chemical parameters obtained from apparently healthy aged people followed over ten years].

The author assessed the physiological aging parameters of 38 apparently healthy subjects who were over 80 years old 1989, who were not on medication, and who had consulted with the Keio Health Counseling Center over 10 years. All subjects had no history of overt vascular disease and/or malignancy in 1989. In 17 of 38 subjects, physical, hematological and blood chemical parameters when they were in their 70s were analyzed. Many parameters were unchanged and remained within normal limits for ordinary adults. Cataract, atherosclerotic change of optic fundi and diagonal ear lobe creases were seen in all subjects during the study period. Concerning standard deviations, those of forced expiratory volume in one second/predicted vital capacity and pure tone average (acoustic ability) decreased with age, unlike those of other parameters. Furthermore, multiple regression analysis, revealed that serum albumin decreased but pure tone average, Scheie's atherosclerotic score, senile cataract, HDL-cholesterol blood urea nitrogen and forced expiratory volume in one second/predicted vital capacity increased with age. This study was not cohort study with selected subjects but shows very slight change of almost any parameter irrespective of age and abnormality can suggest the existence of disease.

Aged↗
PubMed1993

[Endolotherapy of massive bleeding from the small intestinal angiodysplasia in 80-year-old patient].

Angiodysplasia is one cause of chronic gastrointestinal tract bleeding that can not be difficult to detect. In particular, angiodysplasia in the small intestine is very rare and has seldom been reported. An 80-year-old man complained of hematochezia and was admitted to other hospital on October 1991. However, no bleeding sites in the gastrointestinal tract could be revealed by radiographic and endoscopic examinations. After 8 months, he was admitted to our hospital with the same symptom on June 1992. He suffered hemorrhagic shock due to continuous bleeding. Hypotension and anemia progressed in spite of immediate blood transfusion. Emergency angiography revealed extravasation from a peripheral branch of the jejunal artery, in addition tortuous and dilated ileal arteries. Embolization was performed with the catheter inserted superselectively into the nearest arcade of the segmental branch of the vasa recta. After embolization, no complications were occurred. He was discharged and is being followed up as an outpatient.

Aged↗