Biomedical subjects

S Takata

Publications and source records attributed to S Takata.

At least 109 records · Page 6Linked to original sources

PubMed1993

Myocardial perfusion imaging and dynamic analysis with technetium-99m tetrofosmin.

Technetium-99m tetrofosmin is a new myocardial perfusion imaging agent that accumulates rapidly and shows slow clearance from the myocardium. Dynamic acquisition and SPECT imaging were performed in a total of 26 patients. Using exercise-rest protocol, the single-photon emission computed tomography (SPECT) findings of 130 myocardial segments were classified as infarction, ischemia and partial filling and compared to those with 201Tl. Complete concordance of findings was obtained in 108 segments (83%) between images with 99mTc tetrofosmin and 201Tl. Partial filling was observed in 24 segments with 201Tl and 14 segments with tetrofosmin, showing a greater number of ischemic regions in 201Tl. However, in comparison with coronary arteriography (n = 19), overall sensitivity and specificity for detecting coronary artery stenosis (> or = 75%) was 15 of 25 (0.60) and 27 of 32 (0.84), respectively, which did not differ significantly from those of 201Tl, which was 18 of 25 (0.72) and 27 of 32 (0.84), respectively. Graphic analysis that assumes unidirectional transfer of the tracer was applied to initial dynamic changes and uptake constant k and distribution volume V were computed. Multiple vessel disease and congestive heart failure showed a low perfusion index (k/V), and may be used in this type of tracer with unidirectional uptake. This preliminary study in the clinical trial showed the usefulness of 99mTc tetrofosmin as a myocardial perfusion imaging agent.

Coronary Angiography↗

PubMed1993

Enzymatic rate assay of creatinine in serum and urine.

A two-step method for assaying creatinine in serum and urine samples, suitable with automated analyzers, is reported. Reagent 1, for the first step, contains a blanking system [creatine amidinohydrolase (CRTase), urease, glutamate dehydrogenase, NADPH, and 2-oxoglutarate] and a NADPH-regenerating system [Mg(2+)-dependent isocitrate dehydrogenase (ICD), MgCl2, and excess isocitrate]. Reagent 2, for the second step, contains the metal-chelating reagent trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid (CyDTA) and a trigger system [creatinine amidohydrolase (CRNase)]. When a specimen is mixed with reagent 1, all the creatine, urea, and NH3 present are removed by the blanking and NADPH systems. On adding reagent 2, CyDTA inactivates ICD to inhibit the NADPH system. Simultaneously, the creatinine (1 mol) in the specimen is hydrolyzed into creatine by CRNase, and then releases NADP+ (2 mol) through the blanking system. Our optimized method can determine creatinine linearly up to 500 mg/L, with within-day CVs < 1.2% and day-to-day CVs < 2.7%.

Ammonia↗

PubMed1992

Chemoattractants provoke monocyte adhesion to human mesangial cells and mesangial cell injury.

Infiltration of glomerular mesangium by monocytes/macrophages is a prominent pathologic finding in many forms of glomerulonephritis (GN). While the mechanism(s) by which infiltration occurs is incompletely understood, monocyte adhesion to glomerular endothelial cells, provoked by inflammatory mediators, appears to be an important early step. In the present study, we assessed the influence of chemotactic peptides (C5a) and lipids (LTB4 and PAF) on adhesion of human monocytes and mesangial cells, to determine if mesangial cells (glomerular pericytes with smooth muscle properties) represent potential targets for adhesion of chemoattractant-activated monocytes following their diapedesis from the intravascular space. C5a and LTB4 provoked rapid (onset less than 1 min) monocyte-mesangial cell adhesion at nanomolar concentrations via actions with monocytes, while PAF was less potent in this regard. Monoclonal antibodies (mAb) were used to define the monocyte and mesangial cell adhesion molecules involved in these interactions. C5a- and LTB4-induced monocyte adhesion was inhibited (approximately 54%) by mAb against the common beta CD18 subunit of CD11/CD18 leukocyte integrins, while mAb against monocyte L-selectin was without effect. MAb against unique CD11 subunits were used to determine the relative contributions of different CD11/CD18 integrins. In this regard, adhesion was inhibited by mAb against CD11b (approximately 41%), and CD11c (approximately 23%), but not CD11a. MAb against mesangial cell ICAM-1 afforded approximately 27% reduction in adhesion, while mAb against VCAM-1, E-selectin, and P-selectin were without effect. GM-CSF, a cytokine generated by monocytes and mesangial cells, also provoked CD11/CD18-dependent adhesion, and primed monocytes to the actions of chemoattractants.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMed1992

Excitatory role of axon reflex in bradykinin-induced contraction of guinea pig tracheal smooth muscle.

To elucidate the role of the axon reflex in the airways, we studied the effects of atropine (10(-6) M) and tetrodotoxin (10(-7) M) on the bradykinin-induced contraction of guinea pig tracheal smooth muscle, with or without pretreatment of the animals with capsaicin. The concentration-response curves to bradykinin (10(-9) to 10(-5) M) were measured in the presence of both indomethacin and propranolol. In the guinea pigs not given capsaicin pretreatment, baseline tension values did not differ before versus after the application of atropine or tetrodotoxin. Tetrodotoxin reduced the bradykinin-induced contraction significantly, but atropine did not change the contraction induced by bradykinin. These observations indicate that bradykinin-induced contraction is potentiated by a neurally mediated action, but that is not mediated by acetylcholine released from the efferent vagal nerve terminals. The contractile response to bradykinin was significantly reduced in the animals treated with capsaicin as compared with those administered vehicle only. Furthermore, in the animals treated with capsaicin, tetrodotoxin did not affect the response to bradykinin. These observations indicate that bradykinin-induced airway smooth muscle contraction is mediated in part by tachykinins released from C-fiber endings, presumably via an axon reflex.

Animals↗

PubMed1992

Synthetic studies of carbapenem and penem antibiotics. III. A synthesis of a key intermediate for 1 beta-methylcarbapenem.

We synthesized useful intermediates 5 and 6 for 1 beta- and 1 alpha-methylcarbapenems from 4-carboxy-3-[(R)-1-hydroxyethyl]-2-azetidinone 4 as a starting material by using stereoselective hydrogenation and hydroboration, respectively. A practical synthetic route from 4 to the (3S,4S)-4-[(R)-1-carboxyethyl]-3-[(R)-1-hydroxyethyl]-2-azetidinone derivative 1, a useful intermediate for the synthesis of 1 beta-methylcarbapenem antibiotics, was established.

Anti-Bacterial Agents↗

PubMed1992

New actions of parathyroid hormone through its degradation.

Parathyroid hormone degradation is intimately connected with its action. By the action of the unique renal neutral cytosolic PTH ase, PTH is split into 1-34 and 35-84 fragments, and further into 35-70 and 71-84 fragments. Amino-terminal 1-34 peptide was found to participate in the autoregulation of PTH secretion, suppressing the intact PTH secretion both in vivo in humans and in vitro in the dispersed bovine parathyroid cells. C-terminal fragment 35-84 and N-terminal fragment 1-34 both suppress the alkaline phosphatase production by ROS 17/2.8 cells to a lesser extent than the intact PTH 1-84, and the sum of the effects of the two fragments approximately equaled that of the intact hormone. Fragments 35-70 and 71-84 were devoid of such activity. Intracellular free calcium of human vascular endothelial cells was raised by intact 1-84, lowered on the contrary by C-terminal 35-84 fragment, but fragments 1-34, 35-70 and 71-84 had no effect. Fragments generated by the actions, supporting the physiological significance of PTH degradation by its target cells.

Animals↗

PubMed1992

[Contents of chemical mediators in sputum in a case of mycoplasma pneumoniae bronchiolitis resembling bronchial asthma].

A case of Mycoplasma pneumoniae bronchiolitis with hypoxemia is presented. A 41-year-old man was admitted to hospital because of fever, productive cough and dyspnea with wheezing of one month duration. On admission, bronchial asthma was suspected on the basis of reversible airflow obstruction and sputum eosinophilia. However, despite treatment with bronchodilators, his condition did not improve. Chest film and computed tomogram revealed small nodular shadows and tramlines in the bilateral lower lung fields, and pulmonary function tests indicated peripheral airway obstruction. Serologic titer for Mycoplasma pneumoniae was 1:160. A diagnosis of bronchiolitis due to Mycoplasma pneumoniae was made. Improvement of lung function and roentgenographic findings was observed following administration of erythromycin and doxycycline. The concentrations of prostanoids in sputum were markedly higher than in cases of bronchial asthma, and decreased as he improved. These observations suggest that Mycoplasma bronchiolitis should be considered in the differential diagnosis of wheezing, and that measurement of prostanoids in sputum may be useful in the differentiation of infective bronchiolitis and bronchial asthma.

Adult↗

PubMed1991

The role of peripheral capacitance and resistance vessels in hypotension following hemodialysis.

The arterial pressure (AP) response to hemodialysis was studied with echocardiography and strain gauge plethysmography in 17 patients with end-stage renal disease; mean AP was unchanged in seven (group A) and was reduced by more than 10 mm Hg in 10 patients (group B). Following dialysis, body weight decreased and heart rate increased equally in both groups. Ejection fraction did not change in the two groups. Left ventricular end-diastolic volume fell by 13 +/- 10% in group A and by 24 +/- 16% in group B. Cardiac index (CI) fell in group B, but remained unchanged in group A. Systemic vascular resistance (SVR) did not change in both groups. The change in mean AP before and after dialysis was significantly correlated with that in Cl (r = 0.49, p less than 0.05), but not with that in SVR. Calf venous pressure-volume curves were not different between the two groups before dialysis. Hemodialysis shifted the curve toward the volume axis for group B but not for group A. These results suggest that hypotension following dialysis is mainly due to the fall in cardiac output, in which increases in venous distensibility play an important role.

Blood Volume↗

PubMed1991

Calcium treatment of essential hypertension in elderly patients evaluated by 24 H monitoring.

We used 24-h monitoring of blood pressure (BP) to evaluate the effect of calcium supplementation on mild to moderate essential hypertension in elderly hospitalized patients for the first time in a controlled crossover study. The mean systolic and diastolic BP over a period of 24 h declined by 13.6 mm Hg (P less than .005) and 5.0 mm Hg (P less than .05) respectively in patients whose diet was supplemented with 1 g of elemental calcium in the form of oystershell electrolysate (AA calcium). Serum ionized calcium and urinary calcium and sodium excretion increased (serum Ca2+ 0.16 +/- 0.03 mEq/L, P less than .05; FECa 0.5 +/- 0.2%, P less than .05; FENa 0.4 +/- 0.1%, P less than .05) and plasma parathyroid hormone was suppressed (12.2 +/- 2.3 pg/mL, P less than .005). These data suggest that supplementation of dietary calcium may contribute to a reduction of BP in elderly patients with essential hypertension.

Aged↗

PubMed1991

Role of endogenous endothelin in the development of hypertension in rats.

To further elucidate the pathophysiologic role of endogenous endothelin (ET), we have studied the chronic effect of anti-ET gamma-globulin on the development of hypertension in spontaneously hypertensive rats (SHR) and stroke prone SHR (SHR-SP) for three weeks. In neither SHR nor SHR-SP did repetitive bolus injection of anti-ET gamma-globulin suppress the rise in blood pressure. The present data suggest that endogenous ET is not likely to play a key role in the development of hypertension, although ET may induce a local vasoconstriction at the injured vascular wall.

Animals↗

PubMed1991

Magnetic resonance imaging study on spinal cord plasticity in patients with cervical compression myelopathy.

Spinal cord plasticity in 55 patients with cervical compression myelopathy was assessed with magnetic resonance imaging, by which the transverse area of the spinal cord was measured at the site of maximum compression before and after surgery and compared with the conventional modalities of computed tomographic myelography. A high correlation (r = 0.901, P less than 0.01) was observed between the preoperative measurements of magnetic resonance imaging and computed tomographic myelography. The preoperative transverse area was in good correlation with the preoperative Japanese Orthopaedic Association score (r = 0.466, P less than 0.01). In most patients with a spinal cord area of less than 0.45 cm2, the clinical results were poor despite considerable morphologic restoration of the spinal canal obtained after decompression surgery, reflecting an irreversible pathology developed in the spinal cord.

Adult↗

PubMed1990

Autocrine effect of endothelin on DNA synthesis in human vascular endothelial cells.

To elucidate the role of endogenous endothelin on DNA synthesis in endothelial cells, we have investigated the effects of rabbit anti-ET gamma globulin on DNA synthesis in cultured human vascular endothelial cells. DNA synthesis was markedly inhibited by anti-ET gamma globulin in a concentration dependent manner in the presence of fetal calf serum(FCS) (x5000;34%, x2500;54%, x1000;70%), but not in the absence of FCS. These data suggest that endogenous ET modulates FCS-stimulated DNA synthesis in an autocrine fashion.

Animals↗

PubMed1990

Rapid Ca2+ refilling system of intracellular store(s) in human vascular endothelial cells.

Using a fura-2 method, cytosolic Ca2+ concentration [( Ca2+]i) was measured in endothelial cell monolayers from human umbilical vein. In the presence of 1.5 mM Ca2+, bradykinin (BK) induced a rapid (within 15 sec) and dose-dependent (10(-8)-10(-6) M) increase in [Ca2+]i, consisting of an initial peak and a subsequent sustained phase. The pretreatment with 3 mM EGTA for 1 min caused a significant reduction in [Ca2+]i levels both of the basal (p less than 0.05) and BK-stimulated initial peak (p less than 0.001). However, the BK-stimulated initial peak was retained in magnitude for at least 5 min under the treatment with EGTA. In contrast, the sustained phase was completely abolished by EGTA treatment. The BK-stimulated Ca2+ transient, once having been completely inhibited by ionomycin (10(-6) M) in the presence of EGTA, was rapidly (within 2 min) recovered to the untreated level by replacing it with fresh medium containing 1.5 mM Ca2+. The present results indicated that BK mobilized Ca2+ from both intracellular and extracellular space(s) and suggest the presence of an extracellular Ca2(+)-dependent rapid refilling system of intracellular Ca2+ store(s) in human vascular endothelial cells.

Benzofurans↗

PubMed1990

Use of pedicled omental flap in treatment of empyema.

Omental pedicle flaps were used in the treatment of patients with acute and chronic empyema with bronchopleural fistula. In 5 patients (group 1) with postoperative acute empyema owing to bronchial stump fistula, an omental covering was applied as a reinforcement to close the fistula. Six patients in group 2 with chronic tuberculous or Aspergillus empyema with multiple fistulas initially underwent open-window thoracostomy or cavernostomy and secondarily had omental transposition. In all patients, the right gastroepiploic vessels were used to provide the blood supply for the flap. Successful closure of the bronchial stump was obtained in all patients in group 1, but 2 of them died of recurrence of their underlying lung carcinoma within 1 year. Five of the 7 patients in group 2 had a favorable outcome, but 2 patients had partial recurrence after omental plombage. From our experience with these patients, we believe that the omental flap is effective for closing fistulas due to postoperative or chronic empyema but has only limited success in patients whose lungs are severely damaged by persistent infection.

Adult↗

PubMed1990

The cellular mechanism of action by vasoconstrictor hormones in cultured rat vascular smooth muscle cells.

The effects of angiotensin (Ang) II, arginine vasopressin (AVP), and serotonin (5-HT) on inositol trisphosphate (IP3) production, cytosolic Ca2+ concentration [( Ca2+]i), and the phosphorylation of 20 kilodalton myosin light chain (MLC) were examined in cultured rat vascular smooth muscle cells (VSMC). These vasoconstrictors immediately induced dose-dependent and concomitant increases in IP3 production, [Ca2+]i, and phosphorylation of 20 kDa MLC. The agonist-induced increases in IP3 production, [Ca2+]i, and phosphorylation of 20 kDa MLC in VSMC were completely blocked by pretreatment with the receptor antagonists for Ang II, V1, and 5-HT2, respectively. These data suggest that receptor-mediated increases in IP3 production, [Ca2+]i, and phosphorylation of 20 kDa MLC by these vasoconstrictors are closely interrelated.

Angiotensin II↗

PubMed1990

Effects of insulin on vasoconstrictor responses to alpha agonist and tilting.

The effects of insulin on vasoconstrictor response were studied in diabetics without autonomic neuropathy. Vasoconstrictor response to phenylephrine was measured before and after insulin injection in 10 diabetics. Mean blood pressure, forearm blood flow, and forearm vascular resistance remained unchanged after insulin administration. But the increase in forearm vascular resistance to phenylephrine decreased significantly and heart rate increased significantly after insulin injection. In 9 diabetics, vasoconstrictor response to tilting was measured before and after insulin injection. Mean blood pressure, cardiac index, and the total peripheral resistance index remained unchanged after insulin administration. However, the increase in the total peripheral resistance index to tilting decreased significantly and heart rate increased significantly after insulin injection. Furthermore, a significant fall in mean blood pressure following tilting was observed only after insulin administration. Although blood glucose levels decreased significantly, no hypoglycemic symptoms occurred. The present study suggests that insulin inhibits vasoconstrictor responses to both alpha agonist and tilting in diabetics.

Adrenergic alpha-Agonists↗

PubMed1990

[A case of modified Fontan operation for complete atrioventricular canal of right dominance with double-outlet right ventricle, common atrioventricular valve regurgitation].

A 6-year-old boy was diagnosed to have complete atrioventricular canal (CAVC) with double-outlet right ventricle (DORV), common atrium and common atrioventricular valve regurgitation. The atrioventricular junction predominantly connected to the right ventricle (right dominance) and the left ventricle was hypoplastic (LVEDV = 64% of normal). The combination of DORV with right dominant CAVC makes more difficult to make intra-ventricular rerouting. A modified Fontan procedure, atrial partition and DeVega's annuloplasty were successfully performed. It is concluded that Fontan procedure might be preferable rather than intra-ventricular rerouting in this case.

Child↗

PubMed1990

[A case of candida endocarditis with consecutive measurement of serum mannan and D-arabinitol concentrations].

We encountered a case of an 83-year-old patient with candida endocarditis. He had been diagnosed as having aortic regurgitation with moderately calcified aortic valve 5 years previously, and had received medication. He was admitted to our hospital because of pancreatic cancer. He had high fever from the time of his admission and antibiotics produced no effect. Candida albicans was detected in arterial blood culture. We also detected antibody against Candida albicans, and investigated serum mannan and the D-arabinitol creatinine ratio several times. We performed echo-cardiographic examination and recorded a vegetation at the aortic valve. Rising antibody titers against Candida albicans, mannan antigenemia and an elevated creatinine ratio were also observed. So we concluded that these examinations were also effective in the diagnosis of candida infection. Finally, this patient died of cerebral hemorrhage and was autopsied. Macroscopic findings showed mass-like vegetation involving the aortic valve, and microscopic findings showed candida organisms scattered within the vegetation.

Aged↗