PubMed Health⌕ Search

Biomedical subjects

M Toyama

Publications and source records attributed to M Toyama.

At least 19 recordsLinked to original sources
PubMed1992

Effects of pentobarbital on heterosegmentally activated dorsal root depolarization in the rat. Investigation by sucrose-gap technique in vivo.

Slow positive cord dorsum (P-) potentials activated by segmental stimulation are believed to reflect primary afferent depolarizations and have been shown to be augmented by barbiturates. However, there have been no data to confirm whether heterosegmentally activated P-potentials also represent primary afferent depolarizations and are similarly affected by barbiturates. We therefore tested whether heterosegmental P-potentials reflect primary afferent depolarizations and how these heterosegmental potentials are affected by barbiturates. Heterosegmentally activated dorsal root (DR) depolarizations (depolarizations evoked in DRs of lumbar segments in response to afferent volleys to cervical segments produced by electrical stimulation of the forepaw) and P-potentials were simultaneously recorded, adapting the sucrose-gap technique for recording DR depolarization in vivo in the rat. Forepaw (heterosegmental) stimulations produced a large depolarization in the DRs of L5-S1 as well as a slow P-potential in the lumbosacral enlargement. Transection of the spinal cord at the level of C1-C2 abolished both the P-potential and DR depolarization activated by heterosegmental stimulation as well as the second component of segmentally (hind-paw) activated P-potential. Bicuculline (100 micrograms/kg, intravenous) augmented the P-potential and DR depolarization produced by heterosegmental stimulation, but larger doses, 400-600 micrograms/kg, eventually suppressed these. However, the drug, in a dose-dependent manner, suppressed both the P-potential and DR depolarization produced by the segmental stimulation. Pentobarbital (10-40 mg/kg, intravenous) suppressed in a dose-dependent manner both the heterosegmental P-potential and heterosegmental DR depolarization and prolonged their peak latencies. By contrast, pentobarbital augmented and prolonged the segmental P-potential and segmental DR depolarization.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Primary angiosarcoma of the right atrium detected by magnetic resonance imaging.

A 20-year-old woman with a primary angiosarcoma of the right atrium is reported. The patient had a cardiorespiratory arrest due to cardiac tamponade with bloody pericardial effusion. Magnetic resonance imaging (MRI) revealed a tumor, which was corroborated by selective coronary angiography. Open-heart surgery was performed. The tumor relapsed however, and she died four months after operation. The tumor was undetectable by echocardiography, but MRI demonstrated a heterogeneous mass with focal areas of high- and low-signal intensity in the right atrium, suggesting that MRI may allow characterization of cardiac tumors.

Adult↗
PubMed1992

[Coronary artery bypass surgery with bilateral internal mammary artery].

Increasing number of coronary artery bypass surgery has been performed utilizing more arterial grafts because of poor long term patency rate of saphenous vein grafts. The risk of bilateral internal mammary artery grafting was studied in two groups of patients who were matched for recognized risk factors such as year of operation, age, gender, extent of coronary artery disease, left ventricular function, completeness of myocardial revascularization, and history of congestive heart failure. The patient groups differed in the fact that they received on internal mammary artery graft or two internal mammary artery grafts. The operative mortality rate was zero in either group. Analysis of operative and postoperative morbidity demonstrated no significant differences except for a slight increase in transfusion requirement, rate of wound infection and use of catecholamine in the group receiving two internal mammary artery grafts (p = 0.1, 0.1 and 0.05, respectively). We conclude at this moment that bilateral internal mammary artery grafting does not increase surgical mortality but increases the use of catecholamine comparing with the ipsilateral internal mammary artery grafting. Since the cases analysed in this study are limited, definitive conclusion should be deferred.

Adult↗
PubMed1992

[Morbidity and mortality of coronary artery bypass surgery in patients 75 years of age or older].

A consecutive series of 30 patients 75 years of age and older who underwent isolated coronary artery bypass graftings during a 6 year period (from 1985 to 1990) was analyzed. This group was compared with a consecutive series of 512 patients under the age of 75 who underwent the same procedure during the same period. The elderly patients had a higher incidence of unstable angina pectoris, left main or triple vessel disease and depression of ejection fraction. There were no deaths in the hospital or within 30 days of operation (0%), but postoperative complication occurred in 26 cases (86.7%) in the elderly patients. Mean postoperative hospital stay was longer in the elderly patients than the younger ones (21.7 +/- 8.7 days, 18.9 +/- 5.9 days, respectively). The factors frequently noted in the elderly cases with major complications were emergency or urgent operation, history of congestive heart failure and diabetes. The factors associated with prolonged postoperative hospital stay in elderly cases were octogenarians, intraoperative blood transfusion, wound complications, perioperative myocardial infarction, pulmonary failure and low cardiac output state. It is concluded that CABG can be performed safely even in elderly patients by the proper postoperative management, in spite of having increased postoperative complications and resulting in a prolonged postoperative hospital stay.

Age Factors↗
PubMed1992

[Evaluation of the surgical results of the interhemispheric approach in comparison with the pterional approach for anterior communicating artery aneurysms].

From 1986 to 1990, 77 cases of ruptured anterior communicating artery (Aco) aneurysms have been operated on through an interhemispheric approach or a pterional approach. In this study, we mainly investigated the following factors: surgical outcome, surgical complications, degree of evacuation of subarachnoid clot, and frequency of symptomatic vasospasm. The difference of outcome between the two surgical groups was not statistically significant. Each operating method had characteristic surgical complications. Pterional approach had a tendency to complicate premature rupture, sacrifice small vessels around the aneurysm, and to result in Korsakoff syndrome and inadequate clipping. Interhemispheric approach was apt to complicate cerebral contusion, bilateral olfactory nerve injury and hemorrhagic infarction due to sacrifice of the bridging veins. The pterional approach could evacuate more of the subarachnoid clot than could the interhemispheric approach, but there was no significant difference in frequency of symptomatic vasospasm depending on which method was used.

Adult↗
PubMed1992

[A case of endometrioid carcinoma arising from endometriosis of the rectum].

A very rare case with rectal endometriosis heterotopic transformed into carcinoma is reported. A 44-year-old female patient underwent colostomy due to ileus. Postoperative examinations revealed submucosal tumors all around the rectum. Low anterior resection and the closure of the colostomy were performed. Thickening in the muscular layer and serosa were observed in the resected specimen, but the mucosal surface was maintained. Histopathological observation revealed glands of the endometrium and connective fibers with glandular adenocarcinoma in the periphery. Transformation of the benign endometrial tissues into carcinoma and squamous metaplasia were observed. A diagnosis of endometrial carcinoma in the rectum was made.

Adenocarcinoma↗
PubMed1991

Pleomorphic xanthoastrocytoma. Ultrastructural, immunohistochemical, and DNA cytofluorometric study of a case.

A case of right frontal pleomorphic xanthoastrocytoma that occurred in a 7-year-old boy is reported clinicopathologically. The patient underwent surgery on September 29, 1988. Histologic diagnosis of pleomorphic xanthoastrocytoma was made because, in addition to the unique pleomorphic histologic features, positive glial fibrillary acidic protein in immunohistochemical staining and characteristic ultrastructural features, i.e., cytoplasmic intermediate fibrils and lipid vacuoles, basal lamina, and abundant reticulin networks were demonstrated. The DNA cytofluorometric analysis of the nuclei of the tumor cells disclosed the main mode to be diploid with polyploid classes (4, 8, 16, and 32C) without any aneuploidy. Despite the presence of many pleomorphic nuclei, DNA histogram of the tumor disclosed very few DNA synthetic cells indicating a biologically inactive nature of the tumor. The patient is still alive and totally asymptomatic 20 months postoperatively.

Astrocytoma↗
PubMed1991

[A predictive value of ventricular tachycardia detected by long-term electrocardiography for sudden cardiac death].

To investigate the predictive value of nonsustained ventricular tachycardia (NSVT) for sudden cardiac death (SCD), 104 patients (37 cases with myocardial disease, 17 with ischemic heart disease, 10 with hypertension, 5 with valvular heart disease, 5 with miscellaneous heart disease and 31 without heart disease) who had NSVT on 24-hour ambulatory electrocardiograms (DCG) were clinically followed. The first survey was performed when mean follow-up period reached to 26 months from the discovery of NSVT and the second one was done 60 months after the first survey. Seven SCD were found during 1st period and 4 additional SCD occurred during 2nd period. The patients with polymorphic NSVT showed more frequent SCD (6 in 11 cases with polymorphic NSVT) than with monomorphic NSVT (5 in 93 cases with monomorphic NSVT), however, the rate of VT, duration and number of episodes recorded on DCG were independent to SCD. Moreover, none of the patients without structural cardiac disease have died suddenly. In this follow-up study, SCD was occurred most frequently in the cases with cardiomyopathy, especially dilated type.

Adolescent↗
PubMed1991

[A case of coronary artery bypass utilizing natural bifurcation of the right internal mammary artery].

A Forty five year old male with unstable angina due to multiple coronary artery stenosis underwent successful complete coronary revascularization utilizing the natural bifurcation of the right internal mammary artery. As this procedure has not been reported in detail previously in the literature and since the use of the natural bifurcation of the internal mammary artery was considered to be useful for the treatment of multiple coronary stenosis, this case was presented. Pre and post operative angiography is included.

Angina, Unstable↗
PubMed1990

Dose response of N-butyl-N-(4-hydroxybutyl)nitrosamine on urinary bladder carcinogenesis in mutant ODS rats lacking L-ascorbic acid synthesizing ability.

With a daily intake of 250 ppm total ascorbic acid, ODS and F344 male rats were given 0.0125%, 0.025% or 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in the drinking water for 12 weeks, and additional groups received 0.05% BBN for 2, 4 or 8 weeks. The experiment was terminated after a total of 36 weeks. A greater response to urinary bladder carcinogenesis was observed in both strains with increasing dose of BBN or longer treatment period. However, the magnitude of urinary bladder carcinogenesis in ODS rats given the higher BBN concentrations and/or long periods of BBN treatment was less than in comparably treated F344 rats, but not with lower concentrations of BBN and/or shorter periods of BBN treatment.

Animals↗
PubMed1990

[Chronic myelomonocytic leukemia transformed from refractory anemia with ring sideroblasts with a rare abnormal chromosome, inv (12)].

We report here a rare transformation from refractory anemia with ring sideroblasts (RARS) to chronic myelomonocytic leukemia (CMML). A rare karyotype, inv (12), was also seen at the phase of CMML. A 76-year-old female consulted a physician because of hoarseness in June, 1983. An anemia was found and blood transfusions were made. In August, 1983, she was referred and admitted to Tsukuba University Hospital for a further examination of anemia. A diagnosis of MDS (RARS) was made by hematological examinations, and pyridoxamine was administered from September, 1983. The monocyte counts in the peripheral blood increased above 1,000/microliters continuously from June, 1985, and an exacerbation of anemia was also seen. At the second admission to our hospital in August, 1988, the diagnostic criteria for CMML by the FAB co-operative group was fulfilled. At that time, chromosomal analysis revealed an abnormal karyotype; 46XY, inv (12) (p13.3 q15). Even at the phase of CMML, ringed sideroblasts were also seen in 2.2% of nucleated cell count in the bone marrow. To our knowledge, only 12 cases have been reported as transformation from another type of MDS to CMML. The present case is thought to be a rare case of transformation of MDS. On the other hand, 8 cases with inv (12) associated with malignant hematological disorders have been reported previously. Four of the above 8 cases were MDS. A relationship between development of MDS and inv (12) was suggested.

Aged↗
PubMed1990

[A case report of bilateral free internal mammary artery bypass grafting reoperation--spontaneous resolution of stenotic LAD graft one year after revascularization].

We experienced a coronary artery bypass reoperation utilizing bilateral free internal mammary artery (IMA) grafts for a 68 year old male with unstable angina due to graft occlusion. Although post-operative early graftgraphy showed LAD graft stenosis, it resolved completely at the second graftgraphy one year after the operation. Recently in situ IMA grafting has become a standard method for coronary artery revascularization because of its long term high patency rate. On the other hand, free IMA grafting has been rarely tried in our country. Though there has been a few reports of the growth and enlargement of in situ IMA graft, similar events in free IMA graft are rare and not found in the literature. We feel our case of spontaneous resolution of free IMA graft stenosis is unique and worth reporting.

Aged↗
PubMed1990

[Dysphagia in olivopontocerebellar atrophy].

Clinical, radiological and manometric studies on thirteen patients with olivopontocerebellar atrophy were performed in order to investigate the characteristics of dysphagia. As a clinical study, a detailed history of dysphagia was taken to distinguish two types of dysphagia, that is to say swallowing disturbance in a narrow sense and passage disturbance. In the radiological study, each phase of swallowing was observed by X-rays with contrast medium (Dionosil). In the manometric study, intraluminal resting pressure in the esophagus and pressure of esophageal contraction after swallowing were measured. The results were as follows: Eight patients had the sensation of swallowing disturbance in a narrow sense and five patients has the feeling of passage disturbance. In X-ray studies four patients had pooling in piriformis sinus and six patients had slight dilatation of the lower esophagus. In manometric studies, six patients had low intraluminal resting pressure of the upper esophageal sphincter, but almost all patients had normal intraluminal resting pressure throughout the esophagus and in the lower esophageal sphincter. Two patients, who had suffered for five and seven years, had loss of both negative and positive wave in the upper esophageal sphincter after swallowing. Another three patients, who had suffered for two, six and seven years, respectively had loss of negative wave in the upper esophageal sphincter after swallowing. Regarding peristaltic wave, eight patients had low amplitude of the wave. Two patients, who had suffered for five and six years, had diphasic shape of the wave. One patient, who had suffered for nine years, had synchronous wave. Nine patients had loss of negative wave in the lower esophageal sphincter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

An interindividual variability in the sensitivity of atrioventricular node to diltiazem in patients with paroxysmal supraventricular tachycardia.

To study the sensitivity of atrioventricular (AV) node to diltiazem in seven patients with paroxysmal supraventricular tachycardia (PSVT), we analyzed the plasma concentration-response relationship of this Ca-antagonist using AH interval as an index for assessing its Ca channel blocking effect on the AV node after an IV infusion (0.4 mg/kg). The postdose AH intervals were prolonged compared with the baseline, and their percentage changes correlated significantly (P less than 0.01) with log-diltiazem concentrations in all patients. However, drug concentrations associated with a 20% prolongation of AH interval differed considerably among the patients (range; 65 to 260 ng/ml), indicating a large interindividual variability in the sensitivity of AV node to diltiazem. These results suggest that the interindividual difference in the responsiveness of AV node to diltiazem-induced Ca channel blocking effect may be one of the possible explanations for the therapeutic failure of this Ca-antagonist for terminating PSVT or preventing its recurrences in certain patients.

Adult↗
PubMed1989

Anomalous origin of anterior choroidal artery.

We report a very rare case of anomalous origin of anterior choroidal artery. In our case anterior choroidal artery arises from internal carotid artery proximal to the posterior communicating artery.

Adult↗
PubMed1989

Familial aortic dissection: a report of rare family cluster.

Acute aortic dissection occurred in three of four siblings without Marfan syndrome. All of them were successfully treated by operation and remain well 6-42 months after operation. Their mother died suddenly in another hospital of acute aortic dissection. All her siblings were dead and cardiovascular disease was suspected in all of them.

Acute Disease↗