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Biomedical subjects

T Kamada

Publications and source records attributed to T Kamada.

At least 721 records · Page 40Linked to original sources
PubMed1986

Recurrent transient ischemic episodes after anticoagulation or bypass operation. Hemodynamic or embolic mechanism.

Three patients who suffered delayed transient ischemic episodes despite adequate anticoagulation or successful extracranial-intracranial (EC-IC) bypass anastomosis were studied. A hemodynamic mechanism was prominent in 1 patient with moderate orthostatic hypotension. After adequate anticoagulation he had further episodes of transient ischemia, which were finally controlled by an EC-IC bypass. Cerebral blood flow studies revealed flow changes with progression of the arterial lesion from stenosis to occlusion. The bypass was patent postoperatively, which suggested that the ischemia in this patient had been hemodynamic in origin. In the other patient the cerebral ischemic symptoms showed a remarkable improvement after the bypass operation. However, ischemia recurred after the operation until anticoagulants were started. Postoperative cerebral ischemia suggested microemboli, whereas preoperatively, it was presumably a hemodynamic phenomenon. In another patient where microembolism was more apparent, anticoagulation controlled the recurrent ischemia after a bypass operation. A hemodynamic as well as embolic mechanism needs to be considered in a cerebral ischemia which recurs after treatment.

Adult↗
PubMed1986

Noninvasive evaluation of aortic regurgitation by continuous-wave Doppler echocardiography.

Continuous-wave Doppler echocardiography was used to examine the aortic regurgitant flow velocity pattern in 32 patients with aortic regurgitation (AR) and 10 patients without AR. The aortic regurgitant flow velocity patterns, characterized by a rapid rise in flow velocity immediately after closure of the aortic valve, high peak flow velocity, and a gradual deceleration until the next aortic valve opening, were successfully obtained in 30 of the 32 patients with AR (sensitivity 94%, specificity 100%). The velocity decline was greater in patients with severe AR; thus, the slope of the velocity decline (deceleration) and the time to decline to half the peak velocity (half-time index) were measured from the flow velocity pattern. The deceleration became greater and the half-time index shortened in accordance with angiographic grading of AR (p less than .01). The deceleration and the half-time index also correlated well with the aortic regurgitant fraction (r = .79, p less than .01; r = -.89, p less than .01). Because the half-time index could be measured easily and independently of Doppler incident angle, it seemed a simple and accurate index of assessing the severity of AR. Thus continuous-wave Doppler echocardiography permitted the noninvasive evaluation of AR.

Adult↗
PubMed1986

Myocardial infarction after acute carbon monoxide poisoning: case report.

A 28-year-old man with acute myocardial infarction after carbon monoxide poisoning is reported. He had chest pain after the exposure to carbon monoxide. The electrocardiogram, serum enzymes, and technetium-99m pyrophosphate scintigrams showed anterior myocardial infarction. The coronary angiogram, which was performed one month after the onset, showed no visible atherosclerotic lesion. As to the cause of myocardial infarction, it is assumed that carbon monoxide reduced the oxygen supply to the myocardium and might induce coronary artery spasm with or without accompanying coronary thrombosis.

Adult↗
PubMed1986

Effect of OKY-046, a thromboxane A2 synthetase inhibitor, on arachidonate-induced platelet aggregation: possible role of "prostaglandin H2 steal" mechanism.

To clarify the mode of action of a selective thromboxane A2 (TXA2) blockade in platelet reactivity, we examined the effect of (E)-3-[4-(1-imidazolylmethyl) phenyl]-2-propenoic acid hydrochloride (OKY-046), a potent TXA2 synthetase inhibitor, on human platelet aggregation induced by arachidonic acid (1 mM) in the absence and presence of aspirin-treated aortic microsomes containing prostacyclin (PGI2) synthetase activity ex vivo. The production of TXA2 and PGI2 in platelet rich plasma was determined by the amounts of their stable catabolites, TXB2 and 6-keto-PGF1 alpha respectively, measured by radioimmunoassay. In the absence of aortic microsomes, OKY-046 (greater than 10(-5) M) produced more than 90% inhibition of TXA2 production, whereas platelet aggregation was less inhibited, about 40% inhibition over control, by OKY-046 in that concentration. In the presence of aortic microsomes, the inhibitory effect of OKY-046 on platelet aggregation was markedly augmented in a dose-dependent manner in proportion to the increment of PGI2 production, which paralleled the OKY-046-induced inhibition of TXA2. These results suggest that a selective TXA2 blockade produces effects on platelet aggregation mainly in dual fashion in the presence of PGI2 synthetase: one is due to mere inhibition of TXA2 synthetase and the other is due to the enhancement of PGI2 production probably involving "prostaglandin H2 (PGH2) steal" mechanism, in which PGH2 accumulated in platelets is partly converted to a substrate of PGI2 synthetase in aortic microsomes to produce PGI2.

Acrylates↗
PubMed1986

Cardiotonic activity of a new inotropic agent, 3,4-dihydro-6-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]-2(1H)- quinolinone (OPC-8212), in the dog with and without beta-blocker and Ca++-antagonist pretreatment.

Hemodynamic effects of a new inotropic agent, OPC-8212 (2(1H)-quinolinone derivative) were studied in anesthetized open chest dogs pretreated with propranolol and diltiazem. Three doses (1, 3 and 10 mg/kg) of OPC-8212 were administered intravenously and the net hemodynamic effect (% change) was obtained by subtraction of the effect of the solvent from the gross effect, since the vehicle has a transient, but significant hemodynamic effect. The maximal inotropic effect occurred 3 minutes after administration: LV dP/dt max and cardiac output (CO) increased by 19 +/- 2.5% and 28 +/- 8.5%, respectively, at 3 mg/kg. These cardiotonic effects were dose-dependent, whereas heart rate, peak LV pressure (PLVP) and mean aortic pressure were minimally changed at any dose. Accordingly, systemic vascular resistance (SVR) decreased in a dose-dependent manner although the decrease was much less than that in administration of isoproterenol. The inotropic effect was not blocked by beta-adrenoceptor blockade (propranolol 1 mg/kg), indicating that the cardiotonic action of this agent is not due to beta-adrenergic stimulation. Thus, this agent could reverse beta-blocker-induced heart failure. During infusion of diltiazem (0.1 mg/kg/min following bolus intravenous administration of 0.5 mg/kg), the increases in LV dP/dt max and CO due to OPC-8212 were similar to those in the control study. In contrast to the effects under beta-adrenoceptor blockade, however, decreased PLVP was restored by OPC-8212. Neither chronotropic nor rrhythmogenic effects were observed in the control or with either pharmacological intervention. These results indicate that OPC-8212 has a potent inotropic action with modest vasodilatory effect even with propranolol or diltiazem pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Beneficial effect of OPC-8212 (3,4-dihydro-6-(4-(3,4-dimethoxy benzoyl)-1-piperazinyl)-2(1H)-quinolinone on myocardial oxygen consumption in dogs with ischemic heart failure.

The effect of a new inotropic agent, OPC-8212 (2(1H)-quinolinone derivative), on myocardial oxygen consumption (MVO2) following intravenous administration (1 and 3 mg/kg/min) was studied in normal and ischemic failing hearts in open chest dogs. Ischemic failing heart was obtained by intracoronary injection of 15-micron microspheres and volume loading. OPC-8212 significantly increased LV max dP/dt and decreased mean aortic pressure, whereas heart rate was not altered in both normal and failing hearts. Despite the remarkable positive inotropic effect, this agent did not increase MVO2 in the normal hearts and even decreased MCO2 in the ischemic failing hearts associated with a decrease in LV end-diastolic pressure and hence, LV chamber size. These results indicate that OPC-8212 does not increase myocardial oxygen demand, probably because the increase in MVO2 by positive inotropic effect is offset by a decrease in MVO2 due to a decrease in chamber size. Thus, OPC-8212 may be promising for the treatment of congestive heart failure with reduced coronary flow reserve.

Animals↗
PubMed1986

Dietary sardine oil increases erythrocyte membrane fluidity in diabetic patients.

The effects of dietary sardine oil rich in eicosapentaenoic acid, C20:5 (EPA), on erythrocyte membrane fluidity and membrane and plasma lipids were investigated in diabetic and control subjects. Before consumption of this oil, the levels of erythrocyte membrane fluidity were lower in the diabetic subjects, as noted in our previous work (Diabetes 1983; 32:585-91). Decreased membrane polyunsaturated fatty acid contents were evident. Daily consumption of 2700 mg of sardine oil for 8 wk increased erythrocyte membrane fluidity, as determined by electron spin resonance using the 12- or 16-stearic acid label. This increase was seen after 4 wk, and the level remained elevated for 8 wk. Membrane EPA of phospholipid acyl-chains significantly increased after 4 wk and was even more apparent after 8 wk. Membrane-free cholesterol to phospholipid molar ratios significantly decreased after 8 wk. Both the diabetic and normal subjects responded to the sardine oil in the same way. After feeding with sardine oil, there no longer were differences in erythrocyte membrane fluidity between the normal and diabetic subjects. We propose that improvement in membrane fluidity may contribute to the amelioration of altered cell membrane functions in diabetic patients.

Adult↗
PubMed1986

State of systemic hemodynamics in a case of juxtaglomerular cell tumor.

A renin-producing juxtaglomerular cell tumor was found in a 27 year-old woman. The infusion of angiotensin II analogue produced a marked decrease in arterial pressure. Oral administration of captopril also reduced her blood pressure. Although the renal vein renin did not indicate the laterality of the tumor, unilateral partial nephrectomy cured the disease. This is the first case report to describe measurement of several hemodynamic parameters before and after surgical removal of a juxtaglomerular cell tumor.

Adult↗
PubMed1986

[Quantitative integrated backscatter characteristics in the normal and infarcted canine myocardium].

To develop ultrasonic cardiac tissue characterization, serial changes in intensity of backscattered ultrasound from the normal and infarcted myocardium were studied in vitro, with frequency-domain analysis. As an index of backscattered signal intensity, quantitative integrated backscatter [(10 X log-S2/S1)] (dB), S1 and S2 = areas of power spectra of digitized (sample rate = 100 MHz, 8 bits) ultrasonic signals from a perfect reflector and good specimens) were calculated for 60 regions of the myocardium (N = 20, MI = 40) excised from 10 dogs 3 days, 1, 2, and 4 weeks after coronary artery ligation in 2, 3, 3, and 2 dogs, respectively. The myocardial specimens and a stainless steel reflector were mounted at the focal distance of a newly-developed wide-band transducer having a center frequency of 4.0 MHz, in a water bath filled with degassed physiological saline. Tissue concentrations of hydroxyproline (HP) were also established using a HPLC (Hitachi amino acid analyzer model 835). The results obtained were as follows: 1. No significant changes in the integrated backscatter of the normal myocardium were observed throughout the experimental period (3 days = -52.5 +/- 0.7, one week = -53.6 +/- 1.8, two weeks = -51.6 +/- 0.8, four weeks = -52.8 +/- 1.4 (dB) (mean +/- SE). 2. Integrated backscatter of the infarcted myocardium [3 days = -47.3 +/- 0.6, one week = -49.2 +/- 1.3, two weeks = -40.7 +/- 1.3, four weeks = -39.6 +/- 2.0 (dB)] was significantly increased compared with the integrated backscatter of the normal myocardium in the early stage of myocardial infarction, before tissue concentrations of hydroxyproline increased, as well as in the chronic stage of myocardial infarction. 3. Results of histological examinations suggest that minute changes in structure, such as interstitial edema or neovascular proliferations, may be the cause of an early increase in integrated backscatter. The results suggest that quantitative integrated backscatter is a sensitive parameter for detecting both early and old myocardial infarction by cardiac tissue characterization.

Animals↗
PubMed1986

Plasma concentration and peritoneal clearance of oxalate in patients on continuous ambulatory peritoneal dialysis (CAPD).

Accumulation of oxalate, resulting in high plasma levels, is a common finding in end-stage renal disease. We investigated plasma concentration and peritoneal clearance of oxalate in 14 patients on continuous ambulatory peritoneal dialysis. The plasma oxalate levels in these patients (30.2 +/- 11.2 mumol/l) were as high as those in hemodialysis patients before dialysis (31.9 +/- 11.1 mumol/l). There was a significant correlation between plasma oxalate and urea nitrogen appearance (UNA). Dietary protein seems to be an important oxalate source in these patients, because the UNA reflects protein intake in stable patients. The mean peritoneal oxalate clearance was 6.64 +/- 1.56 l/day, close to the creatinine clearance. These results suggest that the plasma oxalate levels in CAPD patients may be sufficiently high to induce calcium oxalate deposition, and that methods of increasing oxalate removal and reducing oxalate burden are necessary for CAPD patients.

Adolescent↗
PubMed1986

[Analysis of prognostic factors in the multidisciplinary treatment of maxillary sinus carcinoma].

In 247 patients with squamous cell carcinoma of the maxillary sinus, the logistic multiple regression analyses were employed to identify prognostic factors. Among various factors evaluated, use of CT scans in treatment planning (p less than .004), age (p less than .009), location of the tumor (p less than .011), T-stage (p less than .017), and free set-up in radiotherapy (p less than .052) proved to be significant factors independently predictive of survival. The most significant factor in improving survival rate was the use of CT scans in treatment planning which was initiated in 1980. Against our prediction, intra-arterial 5-Fu infusion combined with surgery and radiation did not yield favorable result when compared with combined surgery and radiation. Radiation was combined with surgery, high dose radiation of 50 to 55 Gy delivered in 16 fractions over 4 weeks seemed to show better local control than other dose-fractionations.

Analysis of Variance↗