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T Tagawa

Publications and source records attributed to T Tagawa.

At least 109 records · Page 6Linked to original sources
PubMed1995

Central GABAergic mechanisms are defective in salt-induced hypertension in borderline hypertensive rats.

We examined the role of central GABAergic mechanisms in salt-induced hypertension and exaggerated responses to stress in borderline hypertensive rats (BHR), the first offspring of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). The studies were done in conscious BHR and WKY on high (H) (8% NaCl) or normal (N) (0.3% NaCl) salt diets for 5 weeks. A high-salt diet elevated arterial pressure (AP) (p < 0.01) and augmented pressor responses to shaker stress (p < 0.05) in BHR but not in WKY. Intravenous hexamethonium caused a greater decrease in AP in BHR-H than in BHR-N at rest. Muscimol (a GABA agonist) injected into the central ventricle (i.c.v.) caused a greater decrease in resting AP (p < 0.01) and heart rate (HR) (p < 0.05) and BHR-H than in BHR-N. Renal sympathetic nerve activity (RSNA) did not change in BHR-H, but increased (p < 0.05) in BHR-N during muscimol-induced hypotension, although the magnitudes of muscimol-induced hypotension were greater in BHR-N than in BHR-N. The increases in RSNA in response to intravenous nitroglycerin were similar in BHR-N and BHR-N. Muscimol attenuated pressor and tachycardic responses to stress more in BHR-N than in BHR-N (p < 0.01). Muscimol did not alter AP and HR at rest or their responses to stress in the two groups of WKY. The magnitudes of pressor response to bicuculline (a GABA antagonist) did not differ between the two groups of BHR. These results suggest that a high salt diet may alter the central GABAergic system in BHR, which contributes to salt-induced hypertension and augmented pressor and tachycardic responses to stress.

Animals↗
PubMed1995

[Preoperative plasmapheresis for lung cancer with multiple myeloma].

A 66-old-male admitted to our hospital was diagnosed multiple myeloma (IgA kappa type, Durie & Salmon stage IIIA) and squamous cell lung cancer (c-T2N0M0 stage I). The function of platelets was within a normal range (11.7 x 10(4)/mm3 and the bleeding time of two minutes), but the function of coagulation was reduced (prothrombin time, 13.1 seconds; activating prothrombin time, 45.1 seconds; and antithrombin III, 65%). The hyperviscosity syndrome was anticipated because of high IgA M protein (6,551 mg/dl). Plasmapheresis with 800 ml of fresh frozen plasma was performed before the left lower pulmonary lobectomy and R1 lymph node dissection. Then the function of coagulation was improved (prothrombin time, 12.6 seconds; activating prothrombin time, 31.3 seconds; and antithrombin III, 75%). IgA M protein was also decreased to 4,696 mg/dl. Postoperative bleeding necessitated a second thoracotomy. The cause of postoperative bleeding was the ablasion of the pleural adhesion due to tuberculous pleuritis as well as bleeding tendency of multiple myeloma. The plasmapheresis performed in this case did not fully improve the bleeding tendency. Cases of cancer complicated with multiple myeloma have been increasing and if an operation is needed, plasmapheresis should be considered. The indication and the extent of hematologic restoration to be achieved should be further investigated.

Aged↗
PubMed1994

Relationship between hypotensive effects and plasma concentrations of clonidine in spontaneously hypertensive rats: continuous treatment and sudden termination of clonidine infusion.

1. Clonidine was administered subcutaneously (62.5, 125 and 250 micrograms/kg/day) for 8 days using an osmotic infusion pump in spontaneously hypertensive rats (SHR). Clonidine, administered at 125 and 250 micrograms/kg/day at 48 hr after infusion, respectively, and thereafter were maintained at this level throughout the infusion period. 3. After terminating clonidine infusion, a rapid drug elimination from the plasma was manifested in both groups (125 and 250 micrograms/kg/day) with plasma clonidine levels, resulting in a decrease below 0.5 ng/ml at 4 and 6 hr, respectively. Four hours after terminating clonidine infusion at 125 and 250 micrograms/kg/day, transient but not remarkable increases in blood pressure and heart rate were observed only in the latter group compared with the values before termination. 4. These findings reveal that marked hypotensive effects were induced by relatively high doses (125 and 250 micrograms/kg/day) of clonidine in SHR, but no remarkable withdrawal symptoms after termination of clonidine infusion were observed. Therefore, unwanted withdrawal symptoms probably occur when an extremely high dose (250 micrograms/kg/day or more) of clonidine was infused for a long period (8 days or more) in SHR.

Animals↗
PubMed1994

Effect of L-arginine on acetylcholine-induced endothelium-dependent vasodilation differs between the coronary and forearm vasculatures in humans.

OBJECTIVES: The goal of this study was to determine whether the effect of L-arginine on endothelium-dependent vasodilation evoked with acetylcholine differs between the coronary and forearm vasculatures in humans. BACKGROUND: Administration of L-arginine, a substrate in the production of endothelium-derived nitric oxide, may stimulate the release of nitric oxide. METHODS: Seven patients with normal coronary angiograms and seven with mild coronary artery disease and hypertension underwent coronary arteriography and an intracoronary Doppler catheter technique, and the diameter of the large epicardial coronary artery and coronary blood flow were measured. Forearm blood flow was measured by use of a strain gauge plethysmograph. RESULTS: Before L-arginine administration, acetylcholine (1 to 30 micrograms/min) increased coronary blood flow with modest vasoconstriction of a large coronary artery. Acetylcholine (4 to 24 micrograms/min) also increased forearm blood flow. The acetylcholine-induced increases in coronary and forearm blood flow were significantly less in patients with coronary artery disease than in control patients. Intracoronary infusion of L-arginine at 50 mg/min did not alter responses of the large coronary artery diameter or coronary blood flow to acetylcholine in either group. In contrast, L-arginine at 10 mg/min significantly (p < 0.01) augmented the forearm blood flow response to acetylcholine (4 to 24 micrograms/min) to a similar extent in the two groups. CONCLUSIONS: The effect of L-arginine on acetylcholine-induced vasodilation differs between the coronary and forearm vasculatures in humans. It is suggested that impaired acetylcholine-induced coronary and forearm vasodilation in patients with coronary artery disease and hypertension may not be related to a limited availability of L-arginine.

Acetylcholine↗
PubMed1994

Improvement of therapeutic effect by using Fab' fragment in the treatment of carcinoembryonic antigen-positive human solid tumors with adriamycin-entrapped immunoliposomes.

To improve the therapeutic efficiency adriamycin entrapped in antibody-conjugated liposomes, Fab' fragment was used instead of the whole antibody molecule. The murine monoclonal antibody, 21B2, against human carcinoembryonic antigen (CEA) was digested with pepsin, and the thiol residue of intra-heavy chain produced by reduction of F(ab')2 with dithiothreitol was conjugated to liposomes containing adriamycin. The tissue distribution of adriamycin delivered with these liposomes was studied in BALB/c nu/nu female mice bearing CEA-positive human gastric cancer strain MKN-45. An increase in delivery of adriamycin to the tumor was observed in the mice given liposomes with Fab' fragment as compared to those given liposomes with whole antibody. However, the preferential distribution of adriamycin in liposomes to the reticuloendothelial cells remained the same regardless of the use of Fab' fragment. For investigation of in vivo therapeutic effect, three i.v. injections of free adriamycin or adriamycin in liposomes equivalent to 5 mg/kg were given, and adriamycin in Fab' fragment-conjugated liposomes was found most effective in the inhibition of tumor growth. This was confirmed in terms of actual tumor weights excised and CEA concentration in the blood, as well as by pathological observations. The advantages of using Fab' fragment instead of whole antibody are discussed.

Animals↗
PubMed1994

Effects of L-arginine on impaired acetylcholine-induced and ischemic vasodilation of the forearm in patients with heart failure.

BACKGROUND: Endothelium-dependent vasodilation in response to acetylcholine (ACh) and ischemic vasodilation during reactive hyperemia are attenuated in the forearm of patients with heart failure (HF). It has been shown that L-arginine augments endothelium-dependent vasodilation in healthy subjects. Thus, the aim of the present study was to determine if L-arginine improves endothelium-dependent and ischemic vasodilation in the forearm in HF. METHODS AND RESULTS: Forearm blood flow was measured by a strain-gauge plethysmograph in 20 patients with HF and in 24 age-matched control subjects (C). Resting forearm vascular resistance (FVR) was significantly higher in HF than in C (37 +/- 4 versus 22 +/- 2 U, P < .01). Intra-arterial infusions of ACh or sodium nitroprusside (SNP) at graded doses progressively decreased FVR in HF as well as in C. The magnitude of ACh-induced vasodilation was attenuated in HF (P < .01), whereas SNP-induced vasodilation was similar between the two groups. The minimal FVR during reactive hyperemia after 10 minutes of arterial occlusion was significantly higher in HF (n = 12) than in C (n = 12) (3.2 +/- 0.4 versus 2.1 +/- 0.1 U, P < .05). L-Arginine significantly augmented maximal vasodilation evoked with ACh and decreased minimal FVR during reactive hyperemia in HF (P < .01) but not in C. L-Arginine did not affect SNP-induced vasodilation in HF or C. CONCLUSIONS: Our results suggest that defective endothelial function may contribute to impaired ischemic vasodilator capacity in HF.

Acetylcholine↗
PubMed1994

Role of nitric oxide in reactive hyperemia in human forearm vessels.

BACKGROUND: The role of nitric oxide (NO) in reactive hyperemia (RH) is not well known. We investigated whether NO plays a role in RH in human forearm vessels by examining the effects of NG-monomethyl-L-arginine (L-NMMA), a blocker of NO synthesis, on reactive hyperemic flow. METHODS AND RESULTS: Forearm blood flow (FBF) was measured by strain-gauge plethysmography with a venous occlusion technique. The left brachial artery was cannulated for drug infusion and direct measurement of arterial pressure. To produce RH, blood flow to the forearm was prevented by inflation of a cuff on the upper arm to suprasystolic pressure for intervals of 3 and 10 minutes. After the release of arterial occlusion (AO), FBF was measured every 15 seconds for 3 minutes. Resting FBF was 4.3 +/- 0.3 mL.min-1.100 mL-1 before 3 minutes of AO and 4.1 +/- 0.6 mL.min-1.100 mL-1 before 10 minutes of AO. FBF increased to 32.3 +/- 1.9 and 38.2 +/- 3.1 mL.min-1.100 mL-1 immediately after 3 and 10 minutes of AO, respectively, and gradually decayed (n = 13). Intra-arterial infusion of L-NMMA (4 mumol/min for 5 minutes) decreased baseline FBF (P < .01) without changes in arterial pressure. L-NMMA did not affect the peak reactive hyperemic FBF after 3 and 10 minutes of AO. L-NMMA significantly decreased total reactive hyperemic flow (flow debt repayment) by 20% to 30% after 3 and 10 minutes of AO. Simultaneous infusion of L-arginine (a precursor of NO) with L-NMMA reversed the effects of L-NMMA. CONCLUSIONS: Our results suggest that NO plays a minimal role in vasodilation at peak RH but plays a modest yet significant role in maintaining vasodilation after peak vasodilation. Our results also suggest that reactive hyperemia in human forearms is caused largely by mechanisms other than NO.

Adult↗
PubMed1994

Role of nitric oxide in exercise-induced vasodilation of the forearm.

BACKGROUND: We wished to determine the role of NO in exercise-induced metabolic forearm vasodilation. METHODS AND RESULTS: Young healthy volunteers (n = 11) underwent static handgrip exercise (4 to 5 kg, 3 minutes). Forearm blood flow (FBF) measured by strain plethysmography increased from 4.1 +/- 0.7 mL.min-1.100 mL-1 at rest to 9.8 +/- 1.2 mL.min-1.100 mL-1 immediately after exercise and gradually decreased thereafter. Exercise was repeated after intrabrachial artery infusion of NG-monomethyl-L-arginine (L-NMMA) at 4.0 mumol/min for 5 minutes. L-NMMA did not alter blood pressure and heart rate. L-NMMA decreased FBF at rest to 2.9 +/- 0.4 mL.min-1.100 mL-1 (P < .01), peak FBF immediately after exercise to 7.2 +/- 0.7 mL.min-1.100 mL-1 (P < .01), and FBF during the mid to late phase of metabolic vasodilation (P < .01). Calculated oxygen consumption during peak exercise was comparable before and after L-NMMA. Intra-arterially infused L-arginine (10 mg/min, 5 minutes) reversed the inhibitory effect of L-NMMA. To determine the effect of the decrease in resting FBF on exercise-induced hyperemia, we normalized FBF after exercise by resting FBF. The percent increases in FBF after exercise from resting FBF were similar before and after L-NMMA. Furthermore, we examined the effect of intra-arterially infused angiotensin II on FBF at rest and after exercise (n = 7). Angiotensin II decreased FBF at rest from 3.1 +/- 0.3 to 1.8 +/- 0.3 mL.min-1.100 mL-1 (P < .01), peak FBF after exercise from 8.1 +/- 0.5 to 5.6 +/- 0.5 mL.min-1.100 mL-1 (P < .01), and FBF during the mid to late phase of metabolic vasodilation. The effects of L-NMMA and angiotensin II on FBF at rest and exercise were similar. CONCLUSIONS: Our results suggest that L-NMMA decreased FBF after exercise largely by decreasing resting FBF. These results suggest that NO may not play a significant role in exercise-induced metabolic arteriolar vasodilation in the forearm of healthy humans.

Adult↗
PubMed1994

Nitric oxide influences neuronal activity in the nucleus tractus solitarius of rat brainstem slices.

Nitric oxide (NO) is shown to be synthesized in the central nervous system as well as in vascular endothelial cells. However, the physiological role of NO in cardiovascular regulation in the central nervous system remains unclear. The present study examines whether NO plays a role in the regulation of neuronal activity in the nucleus tractus solitarius (NTS). Single-unit extracellular recordings were obtained from NTS neurons in slices (400 microns) of the rat brainstem, which had spontaneous discharges at a frequency of 0.5 to 3 spikes per second. Eighty-one neurons were tested for sensitivity to L-arginine, which is the physiological precursor of NO. L-Arginine (10(-7) to 10(-4) mol/L) increased neuronal activity dose dependently in 33 (40.7%) of 81 neurons tested, but D-arginine (10(-5) mol/L) did not. The neurons that responded to L-arginine responded to glutamate as well. NG-Monomethyl-L-arginine (10(-5) to 3 x 10(-5) mol/L), an inhibitor of the formation of NO, dose-dependently blocked increases in the neuronal activity evoked with L-arginine (10(-5) mol/L). Hemoglobin (1.5 mg/L), a trapper of NO, and methylene blue (10(-5) mol/L), an inhibitor of guanylate cyclase, also blocked increases in the neuronal activity evoked with L-arginine (10(-5) mol/L). Sodium nitroprusside (SNP, 10(-5) to 10(-4) mol/L), which spontaneously produces NO, increased the neuronal activity in the neurons that responded to L-arginine. SNP did not alter the neuronal activity of the neurons that did not respond to L-arginine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Hypomelanosis of Ito associated with hemimegalencephaly].

A girl aged 1 year and 2 months with hypomelanosis of Ito was reported. She suffered from intractable epileptic seizures since the second day after birth. Characteristic bizarre hypopigmented skin lesions were seen on her left shoulder and extended in a linear fashion to the flexion side of the left upper extremity. Brain MRI revealed diffuse enlargement of the left hemisphere, dilatation of the left lateral ventricle, and neuronal migration anomalies, indicating hemimegalencephaly. The types of her seizures were secondarily generalized or unilateral initially, followed by infantile spasms at 1.5 month. Around 4 months of age, frequent partial seizures appeared. Her seizures were intractable despite vigorous anticonvulsant therapy. As patients with hypomelanosis of Ito are frequently associated with neurological abnormalities, brain MRI studies were thought to be essential in detecting central nervous system anomalies, particularly in the presence of early onset intractable seizures.

Brain↗
PubMed1994

Effects of a novel dihydropyridine calcium antagonist on venous capacitance in Wistar-Kyoto rats.

Calcium antagonists are potent dilators of resistance vessels but do not dilate capacitance vessels. CD832 is a novel dihydropyridine calcium antagonist which has a nitrate moiety in its chemical structure. The authors examined the effects of CD832 on venous capacitance in anesthetized rats. Venous capacitance was assessed by measuring mean circulatory filling pressure (MCFP) at three levels of blood volume. Nitroglycerin decreased and phenylephrine increased MCFP. CD832 did not alter MCFP. After treatment with hexamethonium to prevent reflex venoconstriction, CD832 significantly decreased MCFP but nicardipine (another dihydropyridine calcium antagonist) did not. The magnitude of hypotension caused by CD832 and nicardipine was comparable. The results suggest that CD832 is a unique calcium antagonist which has a venodilator effect.

Animals↗
PubMed1993

Decreased blood coagulation activities in carbohydrate-deficient glycoprotein syndrome.

The carbohydrate-deficient glycoprotein (CDG) syndromes are a newly recognized group of inherited metabolic diseases. We report a Japanese brother and sister with a CDG syndrome. Both patients showed decreased activities of blood coagulation Factor XI and of the coagulation inhibitor protein C. In one of them there was also a somewhat decreased activity of Factor IX and of antithrombin III. Isoelectric focusing of antithrombin III revealed a decrease of negatively charged fractions and an increase of more cathodal bands. Furthermore, there was a discrepancy between activity and antigen level of Factor VIII and protein C. The patients had an incidental deficiency of factor XII. This is the first detailed report on blood coagulation systems in the CDG syndromes. These blood coagulation abnormalities may explain at least in part the thrombotic or haemorrhagic complications of the CDG syndromes.

Antithrombin III↗
PubMed1993

Inflammatory pseudotumor in the submandibular region. Clinicopathologic study and review of the literature.

A rare case of right submandibular inflammatory pseudotumor in a 63-year-old man is reported. The tumor appeared as a symptomless swelling in the submandibular region and resembled a malignant neoplasm on computed tomographic and magnetic resonance images. Surgical resection was required. The pertinent English and Japanese literature is reviewed, and histologic and electron microscopic findings are discussed.

Granuloma, Plasma Cell↗