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Biomedical subjects

T Okamura

Publications and source records attributed to T Okamura.

At least 379 records · Page 21Linked to original sources
PubMed1994

Role of nitroxidergic nerve in dog retinal arterioles in vivo and arteries in vitro.

Functional role and anatomic location of nitroxidergic nerves were determined in dog retinal arteries and arterioles. Isolated retinal central arteries responded to nicotine with relaxations that were not influenced by atropine, timolol, or indomethacin and damage of the endothelium, but were abolished by hexamethonium, methylene blue, and oxyhemoglobin. The relaxation was abolished by NG-nitro-L-arginine (L-NNA), a nitric oxide (NO) synthase inhibitor, and was restored by L-arginine. Relaxations caused by NO were not affected by L-NNA. Transmural electrical stimulation at 5 Hz relaxed the strips; the relaxation was abolished by L-NNA and tetrodotoxin. In anesthetized dogs, intraarterial injections of nicotine dilated retinal arterioles in the fundus oculi. This effect was abolished by L-NNA and restored by L-arginine. Intravenous injections of L-NNA constricted retinal arterioles, the effect being prevented by hexamethonium. There were nerve bundles and fibers containing NO synthase immunoreactivity in the adventitia and media in the retinal artery. These findings are consistent with our hypothesis that NO liberated from vasodilator nerves acts as neurotransmitter in dog retinal arteries and arterioles, and the arteriolar muscle tone is regulated by vasodilator nerve activity in vivo.

Amino Acid Oxidoreductases↗
PubMed1994

Patterns of interruption of atrial flutter induced by rapid atrial pacing.

We evaluated the patterns of interruption of atrial flutter (AFl) induced by rapid atrial pacing in 10 patients using standard electrophysiologic techniques. We observed 3 patterns of interruption of AFl: 1) interruption resulting from block of an orthodromic wavefront within the reentry loop in 5 patients; 2) interruption when pacing impulses no longer captured all of the recording sites in the atrium during rapid atrial pacing in 2 patients, and 3) interruption with 1 echo wave after the cessation of pacing in 3 patients. These findings suggest that there are patterns of interruption of AFl other than that resulting from a simple block of an orthodromic wavefront within the reentry loop.

Aged↗
PubMed1994

Observation of sleep-related breathing disorders in patients with coronary artery disease by ambulatory electrocardiogram-respiration monitoring system.

Eighty-five coronary artery patients examined using an ambulatory electrocardiogram-respiration monitoring system (AERMS) in which a respiratory sensor was strapped to the right upper abdominal wall. Apnea was defined as a cessation of abdominal wall movement lasting at least 10 sec. Sleep-related breathing disorder (SRBD) was diagnosed if at least 30 apneic episodes were observed during sleep. The cardiac events evaluated during follow-up included occurrence of sudden death, myocardial infarction and ventricular tachycardia. SRBD was detected in 9 of 85 patients (11%). There were more patients with low EF (EF < 50%) in the SRBD group than in the non-SRBD group (p < 0.01). During follow-up for a mean period of 18.4 +/- 7.6 months after ambulatory recording, four of nine (44%) patients in the SRBD group had cardiac events, compared with only four of 79 (6%) patients in the non-SRBD group (p < 0.001). Thus, coronary artery patients who were complicated with SRBD showed poor cardiac function and had a high incidence of cardiac events.

Aged↗
PubMed1994

Histological and functional studies on the nitroxidergic nerve innervating monkey cerebral, mesenteric and temporal arteries.

Nitroxidergic nerves and their functional role were determined in a variety of monkey arteries. Nitric oxide synthase-immunoreactive nerve fibers innervating the monkey arterial wall were histochemically determined by the use of nitric oxide synthase antiserum. Thin nitric oxide synthase-immunoreactive fibers were consistently found in the outer media of monkey cerebral, mesenteric and temporal arteries, in addition to many thicker fibers and nerve bundles in the adventitia. In the monkey pterygopalatine ganglion, the immunoreactivity was clearly seen in nerve cells, bundles and fibers. Helical strips of monkey arteries were exposed to the bathing media for tension recordings and were stimulated by electrical square pulses. In helical strips of the cerebral artery denuded of the endothelium, transmural electrical stimulation produced relaxations that were abolished by tetrodotoxin or NG-nitro-L-arginine, a nitric oxide synthase inhibitor. In the monkey mesenteric and temporal arterial strips treated with alpha-adrenoceptor antagonists, the relaxation caused by electrical stimulation was also abolished by the nitric oxide synthase inhibitor, and it was restored by L-arginine. Nitroxidergic perivascular nerves, histologically demonstrated, appear to play an important role in dilating the monkey cerebral artery and in counteracting a vasoconstriction associated with noradrenergic nerve activation in the mesenteric and temporal arteries.

Amino Acid Oxidoreductases↗
PubMed1994

Differences in adrenergic nerve and receptor function in dog internal thoracic, coronary and mesenteric arteries.

Isolated dog internal thoracic arteries (ITA) responded to norepinephrine and phenylephrine with concentration-related contractions, which were suppressed by prazosin, but not by yohimbine. Clonidine did not contract ITA. In coronary arterial strips, norepinephrine produced a relaxation. Isoproterenol relaxed coronary arterial strips contracted with serotonin but did not alter the tone of ITA. Forskolin and beraprost, an analog of prostaglandin I2, relaxed coronary and ITA strips to a similar extent. The beta-adrenoceptor density, assayed by [3H]dihydroalprenolol binding, was markedly less in ITA than in coronary arteries. Nicotine and transmural electrical stimulation did not alter the tension of ITA. Immunohistochemical study indicated that nerve fibers containing tyrosine hydroxylase immunoreactivity were markedly less in ITA than in coronary and mesenteric arteries. These results indicate that beta-adrenoceptor function and adrenergic innervation are considerably reduced in dog ITA. Norepinephrine-induced vasocontraction appears to be mediated by alpha 1-adrenoceptors in the arteries.

Animals↗
PubMed1994

[CD7 positive acute myelogenous leukemia exhibiting pleural involvement as an initial manifestation].

A 51-year-old man had suffered from massive pleural effusion due to invasion of malignant cells. The analysis of bone marrow aspiration showed the proliferation of myeloperoxidase-positive blasts. The surface marker analysis of the blasts revealed the positivities for CD7 and CD19 as well as CD13, CD33 and CD34, while the karyotypes of 20 cells were normal. Therefore, CD7 positive AML was diagnosed. The patient was treated with araC and daunorubicin as a remission induction therapy. Peripheral blood stem cells were harvested by leukapheresis after first and second consolidation therapies. Then, 3 x 10(4) cells/kg of CFU-GM were infused. Complete remission has been maintained for 8 months after autologous blood stem cell transplantation. Pleural involvement as an initial manifestation is rare in AML. Extramedullary growth of AML cells may be related to their immaturity, indicated by the expression of the cell surface antigens.

Antigens, CD↗
PubMed1994

[A comparative study of imipenem/cilastatin sodium BID vs QID in the treatment of infections associated with hematopoietic disorders].

Using the envelope method, we allocated 125 patients with infections accompanied by hematopoietic disorders into two groups treated with imipenem/cilastatin sodium (IPM/CS) at a daily dose of 1 g/1 g b.i.d. (group BID) or 0.5 g/0.5 g q.i.d. (group QID), and obtained the following results. 1. In group BID, ANLL was observed in 25 patients; ALL in 6; and NHL in 12. In group QID, ANLL was observed in 27 patients; ALL in 7; and NHL in 13. 2. In group BID, efficacy rates were 54.5% (6/11) in sepsis, 63.0% (17/27) in fever of undetermined origin and 50.0% (4/8) in pneumonia, thus the overall efficacy was 61.8% (34/55). In group QID, efficacy rates were 66.7% (4/6) in sepsis, 76.0% (19/25) in fever of undetermined origin and 35.7% (5/14) in pneumonia, thus the over all was 61.1% (33/54). No significant difference in response rates were observed between the two groups. 3. Bacteriologically, 22 bacterial strains were isolated in group BID and 21 21 strains, in group QID. The eradication rates after treatment with IPM/CS was 100% in group BID and 66.7% in group QID. 4. Side effects were observed in 8 patients in group BID and 3 in group QID. Laboratory examination revealed abnormal values in 9 patients in group BID and 6 in group QID. However, all of the side effects disappeared after the suspension or discontinuation of IPM/CS. The efficacies of IPM/CS therapy for severe infections in patients with hematopoietic disease were similar between 1 g/1 g b.i.d. and 0.5 g/0.5 g q.i.d. groups.

Adult↗
PubMed1994

[New semi-automatic ROI setting system for brain PET images based on elastic model].

We have developed a semi-automatic ROI setting system for brain PET images. It is based on the elastic network model that fits the standard ROI atlas into individual brain image. The standard ROI atlas is a set of segments that represent each anatomical region. For transformation, the operator needs to set only three kinds of district anatomical features: manually determined midsagittal line, brain contour line determined with SNAKES algorithm semi-automatically, a few manually determined specific ROIs to be used for exact transformation. Improvement of the operation time and the inter-operator variance were demonstrated in the experiment by comparing with the conventional manual ROI setting. The operation time was reduced to 50% in almost all cases. And the inter-operator variance was reduced to one seventh in the maximum case.

Brain↗
PubMed1994

[Usefulness of 99mTc-PMT SPECT and 18F-FDG PET in diagnosing orbital metastasis of hepatocellular carcinoma].

We reported a case in which 99mTc-PMT scintigraphy was useful in diagnosing orbital metastasis of HCC. The case involved a 70 y.o. male, who had undergone nine transcatheter arterial embolizations over two years because of HCC and who had a past history of gastric cancer. The patient had complained of headache and visual disturbance for two months. Cranial CT and MRI studies showed a large homogeneous mass with remarkable bone destruction in the right lateral orbital wall. Because AFP was elevated, orbital metastasis of HCC was suspected, and 99mTc-PMT scanning was performed. On the planar and SPECT images, very high uptake was found in the right orbital tumor. The FDG-PET study showed remarkable hypermetabolism in the medial portion of tumor and follow-up MRI revealed that the tumor had expanded and invaded to the medial side of the orbit. 99mTc-PMT scanning was critical in diagnosing this case of orbital metastasis, and FDG-PET imaging was useful in determining the most active portion of the tumor.

Aged↗
PubMed1994

[A case of mesenteric panniculitis: comparing the findings of 67Ga scintigraphy with pathological results].

We report a case of mesenteric panniculitis where we compared the findings of 67Ga-citrate (Ga) scintigraphy with pathological results. The patients, a 75-year-old man, was hospitalized for examination of low abdominal mass. After hospitalization he developed high CRP levels. A Ba enema revealed serrated intestinal walls and a thick fat density, the margins of which were distinct, as judged from abdominal CT scans. Therefore we suspected a mesenteric panniculitis. Since the patient did not improve under conservative treatment for three months, surgery was performed a day after Ga scintigraphy which showed the abnormal uptake in the abdominal mass, which was removed. The radioactivity of several tissue slices from the resected specimen containing the affected part which had been described inflammatory in the pathological examination showed very high radioactivity. This disease is usually diagnosed from the typical findings of Ba enema and CT scan. But, when an extraordinary abdominal accumulation presents, one should think of performing a Ga scan as an additional diagnostic parameter.

Aged↗
PubMed1994

[A case of curatively operated gastric cancer with peritonitis carcinomatosa treated by intraperitoneal administration of CDDP.Etoposide and EAP therapy].

Intraperitoneal administration of cisplatin (CDDP) etoposide (VP-16) and EAP therapy (combination chemotherapy with CDDP, adriamycin (ADM) and etoposide provided the curative resection for advanced gastric cancer with peritonitis carcinomatosa in a 48-year-old woman. She suffered from epigastralgia. CT shows the ascites, and ultrasonography shows Schnitzler metastasis. First, CDDP 100 mg and etoposide 200 mg were given intraperitoneally. Then, the ascites completely disappeared. Next, the patient underwent EAP therapy, after which Schnitzler metastasis disappeared, and total gastrectomy was performed. Macroscopically, it was of H0P0N0S2. Histopathologically, it was poorly differentiated adenocarcinoma and n0s2. She has been doing well with no evidence of recurrence for 18 months after operation.

Adenocarcinoma↗
PubMed1994

[Family make-up is associated with the admission rate of stroke patients--difference between Kochi and Shimane Prefectures and in a rural community].

Kochi Prefecture had a higher admission rate for patients with cardiovascular disease, particularly for stroke, than Shimane Prefecture which has a similar socio-economic level. Kochi Prefecture had a smaller average number of persons in a household, a lower proportion of three generation households, and a lower proportion of households with six persons or more than Shimane Prefecture. The decline in number of persons in a household was greater in Kochi Prefecture than in Shimane Prefecture from 1960 to 1985, especially between 1970 and 1975. The association between family make-up and hospital discharge one year after stroke was examined in a rural community in Kochi Prefecture. Two hundred forty nine patients aged 40 years and older who were admitted immediately after stroke events were registered between 1969 and 1988, and they were followed for one year. According to family make-up, the subjects were divided into four groups: 1) persons who lived with spouse and daughter-in-law, 2) persons who lived with spouse, 3) persons who lived with daughter-in-law, 4) persons who lived without spouse and daughter-in-law. Although mean age and the proportion of serious cases were not different between group 1 and group 4, the proportion of admitted patients of group 1 was significantly lower than that of group 4. About 60% of group 1 had households with six persons or more. Group 2 had the lowest proportion of admitted patients, but this group was significantly younger than other groups. Within group 3, the proportion of admitted patients was higher in households in which the daughter-in-law had a job than in households in which she did not. These results suggest that the high admission rate in Kochi Prefecture is attributable to households which are short of personnel for home care.

Adult↗
PubMed1994

[Evaluation of renal function by factor analysis using 99mTc-MAG3].

The kinetics of 99mTc-mercapto-acetyltriglycine (MAG3), a new renal scintigraphic agent, was studied by factor analysis in patients with chronic renal disorders, and its application to assessment of the renal function was evaluated. Data were collected for 30 minutes from immediately after intravenous injection of MAG3 at 370 MBq, the first pass image and serial renal scintigrams were obtained, and factor analysis was attempted simultaneously. Since most of MAG3 is excreted via the kidney during the first pass, factor analysis was performed. Two factors reflecting renal parenchymal components and pelvic components could be separated in 8 (Cre < or = 2.9 mg/dl) of 10 patients, and they corresponded with respective segmental renograms. In the remaining 2 (Cre > or = 3.0 mg/dl), separation was impossible by 2-factor analysis, and 3-factor analysis was needed. Factor analysis is considered to allow objective evaluation of renal function without setting the ROI.

Adult↗
PubMed1994

Neurogenic relaxations caused by nicotine in isolated cat middle cerebral arteries.

In cat middle cerebral arterial strips denuded of the endothelium, nicotine produced a relaxation that was abolished by treatment with hexamethonium. The relaxation was partially inhibited by treatment with NG-nitro-L-arginine (L-NNA), a nitric oxide (NO) synthase inhibitor, and oxyhemoglobin, an NO scavenger. The remaining relaxation in the media containing L-NNA was abolished in the strips made unresponsive to calcitonin gene-related peptide (CGRP) by its repeated application. However, this was not the case when the strips were made tachyphylaxic to vasoactive intestinal polypeptide. The nicotine-induced relaxation was also partially attenuated by pretreatment with capsaicin; the remaining relaxation was abolished by L-NNA but not by its D-enantiomer. The inhibitory effect of L-NNA was reversed by L- but not D-arginine. Histochemical study revealed that injections of ethanol into the vicinity of pterygopalatine ganglion abolished the positive staining for nicotinamide adenine dinucleotide phosphate diaphorase activity and the CGRP immunoreactivity in perivascular nerves innervating the middle cerebral artery of the ipsilateral side. The nicotine-induced relaxation in the middle cerebral artery from the ethanol-injected side was markedly inhibited compared with that from the nontreated side, whereas the relaxations induced by exogenously applied NO and CGRP were unaffected. We conclude that nicotine stimulates nicotinic receptors in nerve terminals and liberates NO or NO-like substance(s) and CGRP as neurotransmitters in cat middle cerebral arteries.

Animals↗
PubMed1994

[Acquired inhibitors to coagulation factors].

Acquired inhibitors (antibodies) to specific coagulation factors develop in certain underlying disorders such as autoimmune diseases, post-partum period and drug reactions. In about half the patients, no underlying diseases are identified. The majority of the patients have a factor VIII inhibitor. The immunological characteristics of the inhibitors revealed them to be IgG4 with restricted polyclonal nature. The inhibitors to factor VIII recognize epitopes of either heavy chain (44 kDa fragment in thrombin activation) or light chain (72 kDa fragment), or both, which correspond to A2 and C2 domains, respectively, both suggested to be functionally important on the factor VIII molecule. In this symposium, we reported the cases with factor VIII inhibitors and factor V inhibitor and the diagnosis and treatment of these diseases. Further analysis of these inhibitors may be helpful in the management of the patients with severe hemorrhage.

Aged↗