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Biomedical subjects

H Tamura

Publications and source records attributed to H Tamura.

At least 289 records · Page 16Linked to original sources
PubMed1992

Antagonism of medetomidine sedation by atipamezole in pigs.

The efficacy of atipamezole as a medetomidine antagonist was evaluated in pigs. The atipamezole doses (intramuscularly) were 80, 160, 320 and 480 micrograms/kg of body weight, which were one, two, four and six times higher than the preceding medetomidine dose (80 micrograms/kg, intramuscularly). Atipamezole effectively reversed medetomidine-induced sedation, and the optimal action was seen at doses of 160 and 320 micrograms/kg. Recovery from sedation was quick and smooth, and adverse effects such as hyperactivity or tachycardia were minimal with either dose.

Adrenergic alpha-Agonists↗
PubMed1992

A balanced anesthesia with a combination of xylazine, ketamine and butorphanol and its antagonism by yohimbine in pigs.

The effects of intramuscular injections of xylazine (2 mg/kg)-ketamine (15 mg/kg) [X-K15], and xylazine (2 mg/kg)-ketamine (5 mg/kg)-butorphanol (0.22 mg/kg) [X-K5-B] were compared in atropinized (0.05 mg/kg) miniature pigs (pigs). Both combinations induced the anesthesia for more than 1 hr, however X-K5-B induced the more potent and well balanced anesthesia as compared with X-K15, although the amount of ketamine was reduced to one third. The duration of loss of pedal reflex, an indicator of surgical anesthesia, in X-K5-B (62 +/- 13 min) was significantly (P less than 0.05) longer than in X-K15 (28 +/- 19 min). In addition, X-K5-B was accompanied by loss of laryngeal reflex in all pigs. Recovery from anesthesia in X-K5-B was much smoother than in X-K15, and the administration of yohimbine (0.05 mg/kg) could rapidly and smoothly reverse the anesthesia induced by X-K5-B, although it was accompanied by a transient fall in blood pressure and tachycardia. The combination of xylazine, ketamine and butorphanol appears to be a relatively safe and widely available anesthesia for the period of one hour in pigs.

Acid-Base Equilibrium↗
PubMed1992

Sedative effects of medetomidine in pigs.

Sedative effects of medetomidine, a potent selective and specific alpha 2-adrenoceptor agonist, were evaluated in pigs using 5 different doses (30, 50, 80, 100 and 150 micrograms/kg of body weight) and compared with those of xylazine (2 mg/kg). Atropine (25 micrograms/kg) was mixed with both drugs to prevent severe bradycardia. All drugs were administered intramuscularly. Medetomidine at a dosage of 30 micrograms/kg produced more potent sedation than xylazine. The depth of sedation induced by medetomidine was dose dependent within the range from 30 to 80 micrograms/kg. At 100 or 150 micrograms/kg, the depth of sedation was mostly the similar level to that at 80 micrograms/kg but the duration was prolonged. The degree of muscle relaxation produced by medetomidine also seemed to be dose dependent from 30 to 80 micrograms/kg and was stronger than that produced by xylazine. An increase in the duration of muscle relaxation was dose dependent up to 150 micrograms/kg. No analgesic effect was produced by xylazine, however moderate analgesia was obtained by medetomidine. There were no marked changes in heart rate and respiratory rate during the observation period in pigs of any groups, however mild hypothermia after the administration of both drugs was observed. From these results, medetomidine has a significant and dose-dependent sedative effects which are much more potent than that of xylazine, and a combination of 80 micrograms/kg of medetomidine and 25 micrograms/kg of atropine is suitable for sedation with lateral recumbency and moderate muscle relaxation without notable side effects in pigs.

Analgesia↗
PubMed1992

A case of congenital dyserythropoietic anemia type II associated with hemochromatosis.

A 54-year-old woman with anemia, diabetes mellitus and liver dysfunction was admitted to our hospital. Numerous binucleated erythroblasts in the bone marrow, a positive serum acidified test, and the presence of anti I and anti i antigens on the surface of her erythrocytes indicated that she had congenital dyserythropoietic anemia (CDA) Type II. Hemochromatosis was confirmed by a liver biopsy. This case is a sibling of a patient with CDA Type II reported by Omine et al in 1981 (Acta Haematol Jpn 44:1). They report that no physical or hematological abnormalities were found when she was examined at the age of 29 years. Twenty-five years later, she developed CDA Type II and hemochromatosis. This case indicates that long-term observation of the family members of a patient with CDA Type II is necessary.

Anemia, Dyserythropoietic, Congenital↗
PubMed1992

Alterations of anionic charge and/or sites of the glomerular basement membrane in the heterologous phase of passive Heymann nephritis.

Alterations of the anionic charge and/or sites of the glomerular basement membrane (GBM) in the heterologous phase of passive Heymann nephritis (PHN) were studied. Rats with PHN induced by a single injection of anti-Fx1A IgG were examined at days 1, 2, 3 and 4. The left kidney was perfused with ruthenium red (RR) solution as a cationic probe. The RR particles (= anionic sites) in the GBM were counted and expressed as the number of RR particles per unit length of GBM. For quantitative determination of the total anionic charge of the GBM, the GBM-bound ruthenium (= anionic charge) was measured with an atomic absorption spectrophotometer (AAS). Abnormal proteinuria corresponding to a decrease in anionic charge was detected at days 3 and 4. The anionic sites in the lamina rara externa (LRE) adjacent to immune complex (IC) deposits were found to have diminished earlier from day 1 onwards. This diminution was largely confined to areas adjacent to the IC deposits and was significantly correlated with the amount of urinary albumin excretion. Proteinuria in the heterologous phase of PHN would thus appear to be causally related to a decrease in the number of anionic sites in the LRE adjacent to IC deposits.

Animals↗
PubMed1992

[A case of primary amyloidosis associated with giant cell infiltration within a Bowman's capsule].

A 67-year-old man was hospitalized with a diagnosis of nephrotic syndrome. Physical findings at admission were generalized edema and macroglossia. Urinalysis showed massive proteinuria, + +occult blood, and granular and broad casts. Ig A lambda monoclonal gammopathy was noted in the serum. There was no evidence of myeloma in the bone marrow aspirate, scintigram or X-ray of the bone. A biopsy specimen of the kidney showed massive deposits of structureless material in the glomeruli. Marked cell infiltration was also observed in the interstitium. Multinucleated giant cells were occasionally seen in the Bowman's capsules and the interstitium. There were reactive changes in the Bowman's capsule adjacent to the giant cell. The deposits were proved to be amyloid by positive staining with Congo red and apple-green birefringence by polarized light. In addition, microfibrills seen on electron microscopy displayed deposits. Amyloid depositions were observed in other tissues such as gingiva, skin and tongue. Staining of amyloid with Congo red was resistant to potassium permanganate, and amyloid was positively stained with lambda-light chain of immunoglobulin. These findings indicated that the patient had primary amyloidosis. Infiltration of the multinucleated giant cell has been reported only in patients with familial amyloidosis and secondary amyloidosis associated with rheumatoid arthritis. To our knowledge the present case is a first report of the giant cell infiltration in a Bowman's capsule in primary amyloidosis.

Aged↗
PubMed1992

[Clinical experience with the omnicarbon valve prosthesis].

Between January 1985 and March 1990, isolated valve replacements with the Omnicarbon valve were performed in 90 patients aged 34-72 years. There were 53 aortic valve replacements (AVR) and 37 mitral valve replacements (MVR). The cumulative follow-up was 320 patient-year (py) with a mean follow-up of 3.7 +/- 1.4 years. There were 3 operative and hospital mortalities (3.3%), resulting from retrograde aortic dissection during cardiopulmonary bypass, postoperative renal failure, and rupture of infective pseudoaneurysm in ascending aorta. Seven patients died during the late postoperative period, 4 due to valve-related causes. Two of these patients died of prosthetic valve endocarditis (PVE), while the others died of thromboembolism (including valve thrombosis). The overall actuarial survival rate at 6 years was 86.3% (98.8% for AVR, and 82.1% for MVR). There were 2 thromboembolic events (one mesenteric artery thrombosis, and the other valve thrombosis). The linearized incidence of thromboembolism was 0.63%/py. PVE occurred in 3 patients (0.94%/py). One patient (0.31%/py) was found to have a valve dehiscence due to aortitis syndrome. There were no instances of anticoagulant-related hemorrhage, or valve-related hemolysis. The actuarial rate of freedom from valve-related mortality at 6 years was 93.5% (100% for AVR, and 88.1% for MVR). On the basis of a follow-up period of 6 years, good clinical results and a low incidence of valve-related complications can be demonstrated with Omnicarbon valve.

Adult↗
PubMed1992

[Percutaneous transluminal coronary angioplasty in patients with previous coronary artery bypass grafting].

Percutaneous transluminal coronary angioplasty (PTCA) has been used to treat patients with previous coronary artery bypass grafting (CABG). Seven patients with previous CABG underwent coronary artery or vein graft angioplasty following a recurrence of symptoms. Fifteen lesions were attempted in 7 patients. The primary angiographic success rate was 100%. The primary angiographic success rate was defined as reduction of a stenosis by at least 20% of the vessel diameter, leaving a stenosis of less than 60%. There were no complications following PTCA such as death or myocardial infarction. No patients were referred for urgent surgery. Three patients have undergone another PTCA after 3 months and remain well. All patients at follow-up continue to have improved symptoms. Our experience suggests that the patients with recurrence of coronary artery or bypass stenosis following CABG may be suitable for PTCA.

Aged↗
PubMed1992

[Operative results with total composite replacement of the aortic valve and ascending aorta].

From December 1980 to December 1990, ten patients, 9 male and 1 female, ranging in age from 21 to 68 years, were operated on for aortic valve insufficiency associated with an aneurysm of the ascending aorta. The surgical treatment in all cases consisted of total replacement of the ascending aorta with Bentall's procedure (n = 4), or Cabrol's procedure (n = 6). In 5 patients an uncomplicated annulo-aortic ectasia existed. Three of them had annulo-aortic ectasia with an aortic dissection. One had aortitis syndrome, and one had syphilitic aortitis. The operative mortality for the entire group was 0% (0 death). Hospital survivors revealed satisfactory clinical improvement in NYHA class (mean value: 3.2 to 1.0). Late complications developed in 2 of the 10 patients. They had a picture of pseudoaneurysm formation at the anastomoses between the graft and the right coronary 46 months and 15 months, respectively, after the initial operation. Despite the reoperation, one died of hepatic failure 30 days after the operation, and the other died of postoperative bleeding at the anastomosis sites. We, furthermore, considered the difference in aortic cross clamp time and cardiopulmonary bypass time between Bentall's procedure and Cabrol's procedure. Aortic cross clamp time and cardiopulmonary bypass time were significantly shorter in Cabrol's procedure than in Bentall's procedure, if a probability value less than 0.20 was considered to be of statistical significance. We were able to conclude that the treatment of aortic valve regurgitation associated with an aneurysm of the ascending aorta by insertion of a composite graft is a reliable method with low operative mortality and excellent long term results, especially in Cabrol's procedure.

Adult↗
PubMed1992

[Pseudoaneurysm of the left ventricle following mitral valve replacement].

This report describes a false aneurysm of atrioventricular groove in the patients who underwent the reoperation of the mitral valve replacement (MVR). Patient 1 underwent reMVR with a SJM prosthesis because of the malfunction of the previous prosthetic valve. A large hematoma was observed in the posterior atrioventricular groove with bleeding at weaning from cardiopulmonary bypass. Ventricular rupture was repaired under the cardioplegic arrest successfully from the epicardial surface with a woven Dacron felt. The postoperative left ventriculogram revealed the false ventricular aneurysm along the atrioventricular groove. Patient 2 underwent reMVR with Carpentier-Edwards prosthesis because of the malfunction of the previous Carpentier-Edwards prosthesis. Cardiopulmonary bypass was discontinued uneventfully, and there were no clinical symptoms suspicious of the formation of the false left ventricular aneurysm. The left ventriculogram at the discharge showed the false left ventricular aneurysm along the atrioventricular groove. Although both patients are in good condition without significant complications, we should involve in the postoperative care of the patients on a regular outpatient basis.

Aged↗
PubMed1992

[A beneficial effect of glucose-insulin-potassium infusion for intractable ventricular fibrillation--a case of intraoperative myocardial infarction].

A 61-year-old man suffering from compression fracture of the first lumbar vertebra was scheduled for anterior and posterior spinal fusion. Anesthesia was maintained with enflurane, nitrous oxide in oxygen and fentanyl. When his position was changed from right lateral to supine position, ventricular fibrillation (VF) occurred. The operation was discontinued and he was taken into ICU receiving cardiopulmonary resuscitation. Despite ordinary therapies including DC-shock and lidocaine infusion, Vf and defibrillation recurred more than 20 times for the first two hours. Electrocardiogram showed elevation of ST-T segments in II, III, aVF and V1-V3 leads. Because no effective treatment was found, we attempted to use glucose-insulin-potassium mixture, by which Vf stopped. Electrocardiogram taken on the following day showed abnormal Q wave in II, III and aVF leads, and the patient was diagnosed as having had acute myocardial infarction. On the fifth postoperative day, the patient was returned to the ward without neurological deficits. We conclude that glucose-insulin-potassium infusion is a beneficial therapy for Vf, which is resistant to ordinary treatments.

Glucose↗
PubMed1992

[Comparative study of anticoagulant management after coronary artery bypass surgery--warfarin versus dipyridamole].

A prospective randomized study was performed in 137 coronary artery bypass surgery cases to determine if the administration of antiplatelet drugs would improve the patency of coronary artery bypass grafts. The warfarin group received warfarin and thrombotest was controlled to 20% or so. The dipyridamole group received both 300 mg of dipyridamole and 250 mg of aspirin orally each day. These two groups were compared for study in grafts patency. Results were analyzed by chi-square. In the warfarin group, 66 patients had three ITA-LAD grafts and 115 saphenous vein grafts (including 4 sequential grafts). In the dipyridamole group, 71 patients underwent 38 ITA grafts and 167 saphenous vein grafts (including 56 sequential grafts). Eighty-eight of the 107 grafts (82%) were patent in the warfarin group, and 190 of 205 grafts (95%) were patent in the dipyridamole group (p less than 0.01). Of the two ITA grafts in the warfarin group, no graft was occluded, a patency of 100%. In the dipyridamole group, 35 of 38 ITA grafts (92%) were patent. In the warfarin group, 86 of 105 saphenous vein grafts (82%) were patent. In the dipyridamole group, 155 of 167 saphenous vein grafts (95%) were patent (p less than 0.01). In the study of grafted coronary vessel, the patency of left anterior descending coronary artery, diagonal branch and right coronary artery was not significant between two groups. In the dipyridamole group, the patency of left circumflex coronary artery was 93%, and that of the warfarin group was 50% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Induction of neurite outgrowth of PC12 cells by an inhibitor of vacuolar H(+)-ATPase, bafilomycin A1.

Bafilomycin A1, a selective inhibitor of vacuolar H(+)-ATPase, induced neurite outgrowth of PC12 cells dose- and time-dependently: more than 50% of the cells extended neurite-like spikes after 24 h treatment with 100 nM bafilomycin A1. Its dose-response ran roughly parallel to that of a bafilomycin A1-induced lysosomal pH increase. It was inhibited by LiCl, an inhibitor of the phosphorylation of microtubule-associated proteins and, like nerve growth factor (NGF)-induced neurite outgrowth, it was also inhibited by cycloheximide and actinomycin D. But, unlike the NGF-effect, it was not associated with rapid induction of c-fos.

Animals↗
PubMed1991

A new sensitive method for determining endotoxin in whole blood.

We developed a microplate method for determining endotoxin in whole blood with Endospecy, an endotoxin-specific chromogenic limulus test reagent. The factors in blood that would interfere with the test were successfully removed by exposing samples to 0.66 mol/l HNO3 containing 0.25% Triton X-100. Recoveries of various endotoxins spiked into whole blood of humans and experimental animals were almost complete, and were not enhanced by sample dilution. Normal endotoxin concentration in human whole blood was less than 10 pg/ml in reference to Escherichia coli 0111:B4 endotoxin. Measurements on paired whole blood and platelet-rich plasma (PRP) samples from 50 normal and 132 diseased subjects showed a good correlation (r = 0.901, P less than 0.01). This microplate whole blood method has advantages over the conventional PRP method in that it requires less time, less amount of sample and limulus reagent, and less risk of contamination during the procedure.

Animals↗
PubMed1991

Molecular cloning of a cDNA of a camptothecin-resistant human DNA topoisomerase I and identification of mutation sites.

Camptothecin (CPT), a plant alkaloid with antitumor activity, is a specific inhibitor of eukaryotic DNA topoisomerase I. We have previously isolated and characterized a CPT-resistant topoisomerase I isolated from a CPT-resistant human leukemia cell line, CPT-K5. cDNA clones of topoisomerase I were isolated from the CPT-resistant and the parental CPT-sensitive cell lines, respectively. Sequencing of the clones identified two mutations in the cDNA isolated from the resistant cells, which cause amino acid changes from aspartic acid to glycine at residues 533 and 583 of the parental topoisomerase I. When the CPT-K5 topoisomerase I was expressed in E. coli as a fusion protein with Staphylococcal Protein A fragment, the activity was resistant to CPT at a dose level up to 125 microM, whereas the parental fusion protein was sensitive to CPT as low as 1 microM. The resistance index (greater than 125) of the CPT-K5 fusion topoisomerase I is similar to that of the native CPT-K5 topoisomerase I. These results indicate that either or both of the two amino acid changes identified in the mutant enzyme is responsible for the resistance to CPT.

Amino Acid Sequence↗
PubMed1991

Gas chromatographic analysis of malonaldehyde and 4-hydroxy-2-(E)-nonenal produced from arachidonic acid and linoleic acid in a lipid peroxidation model system.

Malonaldehyde (MA) and 4-hydroxynonenal (4-HN) formed upon oxidation with Fe2+/H2O2 from arachidonic acid and linoleic acid, and their ethyl esters were analyzed by gas chromatography (GC). The MA and 4-HN produced were reacted with N-methylhydrazine (NMH) to give 1-methylpyrazole and 5(1'-hydroxyhexyl)-1-methyl-2-pyrazoline, respectively. The derivatives were analyzed by GC on a fused silica capillary column using a nitrogen-phosphorus detector. With arachidonic acid, more MA and 4-HN were formed from the ester (88 nmol/mg and 23 nmol/mg, respectively) than from the free acid (25 nmol/mg and 9 nmol/mg, respectively). In contrast, with linoleic acid, more MA and 4-HN were produced from the free acid (53 nmol/mg and 13 nmol/mg, respectively) than from the ester (39 nm/mg and 8 nmol/mg, respectively).

Aldehydes↗