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Biomedical subjects

M Tada

Publications and source records attributed to M Tada.

At least 415 records · Page 23Linked to original sources
PubMed1990

Detection of oxygen-derived free radical generation in the canine postischemic heart during late phase of reperfusion.

To define the relation between oxygen-derived free radical (oxy-radical) generation in the reperfused ischemic myocardium and the progression of myocardial damage, we measured oxy-radical generation in the ischemic myocardium and the propagating infarct size in a model of canine coronary occlusion (90 minutes) and reperfusion. We used electron paramagnetic resonance spin-trapping techniques (5,5-dimethyl-1-pyrroline N-oxide [DMPO]) to detect oxy-radicals in the rapidly frozen myocardial samples taken by needle biopsy. There was no detectable generation of DMPO adducts in the normal myocardium before or after reperfusion. In the reperfused ischemic myocardium, electron paramagnetic resonance signals of DMPO-OOH (superoxide anion) and DMPO-OH (hydroxyl radical) were detected, with peak concentrations at 1 hour after reperfusion for DMPO-OOH and at 3 hours after reperfusion for DMPO-OH, respectively. These DMPO adducts were also detected during the early phase (15 seconds) of reperfusion, but the concentrations of these signals were much less than those during the late phase of reperfusion. Treatment with human recombinant superoxide dismutase (2.5 mg/kg/hr) and catalase (2.5 mg/kg/hr) during the course of experiments abolished DMPO-OOH formation but had little effect on DMPO-OH formation. Infarct size (percent of risk area infarcted), quantified by a dual staining method with Evans blue dye and triphenyltetrazolium chloride, was 18.3 +/- 4.8% (mean +/- SEM) at 90 minutes of occlusion. After 5 hours of reperfusion, infarct size increased to 43.6 +/- 7.2%. These results indicate that a greater magnitude of oxy-radical generation was sustained in the ischemic myocardial tissue during the late phase (1-3 hours) of reperfusion, associated with the progression of myocardial infarction. The concurrent appearance of oxy-radicals and progressive infarction may support the view that a chain reaction of oxy-radicals contributes to the propagation of myocardial cell damage in the postischemic heart.

Animals↗
PubMed1990

Molecular mechanism of calcium uptake and release by cardiac sarcoplasmic reticulum.

Cardiac sarcoplasmic reticulum (SR) plays a special role in controlling free calcium ions (Ca) in heart muscle cells. Ca stored in the SR is released through the Ca release channels when the sarcolemmal membrane is depolarized, thereby inducing contraction, while Ca is reaccumulated by the Ca pump to induce relaxation. In the latter process, the Ca pump of cardiac SR has a regulatory system by cAMP-dependent phosphorylation of a SR protein, phospholamban. Recently, significant progress has been achieved in understanding the molecular mechanisms of Ca release and uptake and its regulation. The structures of the Ca pump and phospholamban have been defined at molecular levels. A direct interaction between these two proteins was demonstrated. The Ca release channel was identified, and turned out to be the foot structure which in situ connects the SR to the sarcolemma/transverse tubule.

Amino Acid Sequence↗
PubMed1990

[Influence of the changes in food intake patterns and smoking and drinking habits on stroke--20-year follow-up survey in the Oki-Islands, Shimane Prefecture, Japan].

In 1968 (the first survey), the food intake patterns and smoking and drinking habits of the 3,546 male and 4,350 female inhabitants aged 40-74, of the Oki-Islands, Shimane, Japan were investigated. The response rates were 64% for males and 65% for females. A second survey according the same protocol was carried out from 1987 to 1988. A total of 1,140 males and 1,694 females were randomly selected from the cohort members who were completely followed up from 1968 to 1987. The overall response rates at the second survey were 91.2% for male and 88.9% for female. The results are summarized as follows: 1. 'Saltless' dietary habits significantly advanced in both sexes of all age groups (40-49, 50-59, and 60-74 years old in 1968) and in both hypertensives and normotensives; the frequency of pickle intake significantly decreased, while that of miso soup intake did not change. Nutritional improvement was remarkable in that the frequency of fish, meat, eggs, milk, green vegetable and fruit intakes increased in both sexes of all age groups and in both hypertensives and normotensives. 2. The frequency of smoking significantly decreased in all age groups and in both male hypertensives and normotensives, in contrast with that of drinking. The frequencies of smoking and drinking showed the same tendencies in females. 3. The frequencies of smoking, drinking, and miso soup intake were higher in males who died from strokes than in those who died from other causes from 1968 to 1987, in contrast with the intakes of eggs and milk.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Giant internal carotid aneurysm at the cavernous portion with abrupt disappearance of N20 100 minutes after carotid occlusion--case report.

A 69-year-old female with bilateral giant internal carotid aneurysms at the cavernous portion was admitted with complaints of diplopia and radiating pain. The aneurysm on the left side was larger and symptomatic, and treated with the internal carotid artery ligation and the superficial temporal artery-middle cerebral artery (STA-MCA) double bypasses. However, intraoperative somatosensory evoked potential (SEP) monitoring revealed the disappearance of N20 100 minutes after the carotid occlusion and rapid recovery of N20 following flow restoration. Therefore, a high-flow bypass using radial artery grafting was installed, and carotid ligation was performed again without any change in SEP. Postoperative angiograms demonstrated complete disappearance of the aneurysm and sufficient blood supply through a patent high-flow bypass. Although both STA-MCA double bypasses were occluded, no change in cerebral blood flow was detected by single photon emission computed tomography. Her neurological deficits improved, and she is being followed as an outpatient with a plan of second surgery for the remaining aneurysm.

Aged↗
PubMed1990

[Clinical investigation of stercoral ulcer].

Analysis of 14 cases of stercoral ulcer showed that they tended to occur in patients over 70 years of age and associated diseases included heart failure under hemodialysis, cerebral hemorrhage, and postoperative states requiring bet rest for long duration. Constipation is always preceded the occurrence of the disease, and the initial symptoms was generally massive hematochezia of sudden onset. Massive blood transfusion was often required, however, heater probe hemostasis was effective. The most common site of involvement was the rectum, and the shape of ulcer was irregular or round. Measurement of the mucosal blood flow in the rectum revealed that blood perfusion was markedly reduced immediately after the occurrence, and that it recovered with healing of ulcer. Ischemia was considered to participate in the pathogenesis of the disease.

Aged↗
PubMed1990

Structural analyses of sugar chains from ricin A-chain variant.

Two glycopeptides were isolated from a tryptic digest of ricin A-chain variant by gel filtration and reversed-phase HPLC. Their amino acid compositions and sequences showed that Asn-10 and Asn-236 are glycosylated. The sugar chains were liberated from these glycopeptides by hydrazynolysis, N-acetylated, and pyridylaminated. Component analysis and comparison of elution positions of the purified pyridylamino (PA-) sugar chains with those of authentic PA-sugar chains from the major ricin A-chain by reversed-phase HPLC and size fractionation HPLC suggested that both sugar chains linked to Asn-10 and Asn-236 of the ricin A-chain variant are M3FX, identical to that linked to Asn-10 of the major ricin A-chain.

Carbohydrate Conformation↗
PubMed1990

[Immature teratoma of the testis associated with Klinefelter's syndrome: a case report].

A case of testicular immature teratoma associated with Klinefelter's syndrome is reported. The patient was a 6-month-old boy and admitted with the chief complaint of painless mass in the left scrotum. Left high orchiectomy was performed and the pathological diagnosis was immature teratoma of the left testis. He was also diagnosed with Klinefelter's syndrome because chromosome analysis of the tumor tissue and peripheral blood leukocyte revealed 47, XXY, but the only congenital anomaly was overfolded helix. We discuss the association between the testicular tumor and Klinefelter's syndrome.

Humans↗
PubMed1990

[Long-term treatment for non-A, non-B chronic hepatitis--effects on hepatitis C virus (HCV)].

We have treated 16 patients with chronic non-A, non-B hepatitis with short term (7-13 weeks) and long term (1 year) interferon. Sustained effect (normalization) of treatment was noted in all by long term treatment, where 7 of 8 with short term treatment showed flare-ups of transaminase after the therapy. In addition, negative turn of anti-HCV antibody was noted in 2 of 5 patients with long term treatment, whereas such change was noted in none of 6 anti-HCV antibody positive patients treated with short term treatment. These data suggest that long term interferon therapy may change natural course of chronic non-A, non-B hepatitis caused by HCV.

Adult↗
PubMed1990

[Detection of ras gene mutations of primary hepatic malignant tumors by polymerase chain reaction and direct sequencing method].

Ras genes are converted to active oncogenes by point mutations occurring in either codon 12, 13 or 61. We used polymerase chain reaction and direct sequence method for the analysis of these mutations. We examined 13 hepatocellular carcinomas, 8 cholangiocarcinomas, 2 hepatoblastomas and 1 biliary cystadenocarcinoma. Of these tumors, ras gene mutations were detected solely in cholangiocarcinomas. Cholangiocarcinoma showed a high incidence of K-ras gene mutation. Among 8 patients with cholangiocarcinoma, the mutation was detected at codon 12 in 4 and at codon 61 in 1. The incidence of K-ras gene mutation was especially high in the hilar type of cholangiocarcinoma as compared with the peripheral type.

Adenoma, Bile Duct↗
PubMed1990

[Recent advances in diagnosis and treatment of colorectal cancer].

There are several methods to detect colon cancer in asymptomatic people; questionnaire, fecal occult blood test, barium enema study, endoscopy and so on. In our study, patients with colon cancer were easily differentiated from normal subjects by analyses of questionnaire responses, but early cancer was not differentiated well. Immunological fecal occult blood test was enough to screen out cancer correctly. Contrast barium enema and colonoscopy have been necessary to diagnose colon cancer and other lesions. Fine lesions 2-3 mm in diameter can be diagnosed by the skillful double contrast method and more diminutive lesions by the dyeing and magnifying colonoscopy. Endoscopic ultrasonography (EUS) can provide useful information for the diagnosis of cancer. At present, EUS provides information concerning the extension of colorectal cancer with considerable reliability. The video endoscope system with the CCD chip is electronically transmitted to a video processor for display by a television monitor. Application of a computer at the level of image processing is expected to open a new field in endoscopic diagnosis.

Barium Sulfate↗
PubMed1990

N-[18F]fluoroacetyl-D-glucosamine: a potential agent for cancer diagnosis.

Positron labeled substrates such as sugars, amino acids, and nucleosides have been investigated for the in-vivo evaluation of biochemical processes in cancerous tissue. Hexosamines are obligatory structural components of many biologically important macromolecules, including membrane glycoproteins and mucopolysaccharide. We evaluated a new synthesized pharmaceutical, N-[18F]fluoroacetyl-D-glucosamine (18F-FAG), which is a structural analog of N-acetyl-D-glucosamine. C3H/HeMsNRS mice bearing spontaneous hepatomas were used for the tissue distribution study. At 60 min after injection, high uptakes were found in tumor (5.16, mean value of %dose/g), liver (3.71), and kidney (3.27). The tumor uptake of 18F-FAG showed the highest value in all tissue. In the PET study, VX-2 carcinoma of the rabbit was clearly visualized. Our preliminary results suggest that 18F-FAG has potential as a new agent for tumor imaging.

Acetylglucosamine↗
PubMed1990

[Protease activities in gastric and colon cancer tissues].

Activities of cathepsin B, cathepsin L, and plasminogen activators (urinary type plasminogen activator and tissue type plasminogen activator) were assayed in homogenates of cancer tissue, normal tissue closely surrounding the cancer tissue, and normal tissue distant from the cancer tissue from 30 patients undergoing surgery for gastric cancers and 10 patients undergoing surgery for colon cancers. Activities of those proteases were also assayed in homogenates of adenoma tissue from 10 patients undergoing polypectomy for colon polyps. In the gastric cancer tissue homogenates, the activities of cathepsin B, cathepsin L and tissue type plasminogen activator were significantly higher than in normal tissues. By contrast, the activities of urinary type plasminogen activator of gastric cancer tissues were significantly lower than normal tissues. In the colon cancer tissue homogenates, the activities of cathepsin, B, cathepsin L, and urinary type plasminogen activator were significantly higher than in normal tissues. On the other hand, the activities of tissue type plasminogen activator of cancer tissues were significantly lower than normal tissues. But there were no significant differences in the activities of plasminogen activators between the cancer tissues and adenoma tissues. These results suggest that cathepsin B and cathepsin L play an important role in gastric and colon cancer proliferation and evolution, although the roles of plasminogen activators in gastric and colon cancer proliferation and evolution and in the colon adenoma-carcinoma sequence are still unknown.

Cathepsin B↗