Search PubMed⌕ Search

Biomedical subjects

J Shimizu

Publications and source records attributed to J Shimizu.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Meningioma associated with acute subdural hematoma: a case report].

We present a case of meningioma associated with acute subdural hematoma. This 67-year-old male had a sudden onset of severe headache when he was on the train. He had a CT scan which revealed an acute subdural hematoma at the left parietal convex. Cerebral angiography disclosed a small focus (3 x 4 cm) of vascular stain under the left parietal bone supplied by the left middle meningeal artery. He was diagnosed as having a meningioma with surrounding acute subdural hematoma. The removal of this tumor was carried out without delay. It was fragile and the bleeding point was not detected. Pathological diagnosis was meningothelial meningioma. The literature showed meningioma associated with acute subdural hematoma is rare, but when it is discovered incidentally, surgical resection might be indicated.

Acute Disease↗
PubMed1998

[Anesthetic management for Fontan procedure without the use of cardiopulmonary bypass].

We examined the anesthetic management for Fontan procedure performed without the use of cardiopulmonary bypass (Group N, n = 7) and that for equivalent procedure under cardiopulmonary bypass (Group E, n = 10) retrospectively. In Group N, surgical repairs of major vascular system were performed while bypassing the superior or inferior vena cava to the right atrium. The use of anesthetics and vasoactive agents was similar in both groups. Patients in Group N had significantly less blood loss and were extubated significantly earlier than those in Group E. However, significant metabolic acidosis was noted in Group N when reconstruction of the vascular system was completed and so-called Fontan circulation was initiated. Fontan procedure without the use of cardiopulmonary bypass may have advantage of less impairment for the cardiac performance and the pulmonary vasculature. However, its anesthetic management is another challenge to the anesthesiologist and requires meticulous control of both optimum preload and vascular resistance of the pulmonary artery.

Anesthesia, General↗
PubMed1998

The significance of atrial monophasic action potentials for monitoring rat cardiac allograft rejection.

BACKGROUND: Changes in the monophasic action potential may be used for detecting early acute rejection in the transplanted rat heart. METHODS: Heterotopic heart transplantations were performed in allogeneic and syngeneic rats. During atrial pacing, monophasic action potentials were simultaneously recorded in the right atrium and ventricle of the transplanted hearts on postoperative days 1, 3, and 5. The amplitude and duration of monophasic action potentials, atrioventricular conduction time, and cardiac intervals were analyzed. Histopathologic examination for rejection was performed on postoperative days 1, 3, and 5. RESULTS: In the allogeneic group, monophasic action potential amplitude progressively decreased, and monophasic action potential duration gradually increased after heart transplantation in the atrium and ventricle. With rejection, the amplitude decreased to a greater extent, and monophasic action potential duration increased to a greater extent in the atrium than in the ventricle on day 3. The atrioventricular conduction time increased on day 5, but the cardiac interval did not change. An inverse correlation between histopathologic grade and the monophasic action potential amplitude, and a positive correlation between histopathologic grade and the monophasic action potential duration existed for both the atrium and ventricle. These electrophysiologic and histopathologic changes were not observed in the syngeneic group. CONCLUSIONS: We conclude that right atrial monophasic action potentials may be a useful and reliable indicator of early acute heart transplant rejection.

Acute Disease↗
PubMed1997

Renal sympathetic nerve activity and the weight of the remaining kidney in unilateral nephrectomized rats.

To examine compensatory response of the kidney to reduction in renal mass, acute and chronic effects of unilateral nephrectomy on renal sympathetic nerve activity (RNA) and weight of the remaining kidney were analyzed in rats. Under acute nephrectomy, RNA decreased significantly due to ligation of the renal vessels, ureter and nerves. With acute unilateral renal denervation, basal mean RNA (MRNA) did not change but the reflex inhibition of RNA due to ligation disappeared. Chronic effects of nephrectomy were analyzed at 3, 7, 14 and 28 days after surgery. At 3, 7, 14 and 28 days after nephrectomy, MRNA were about two times larger than the values obtained in sham operation group (p < 0.01). Changes in arterial pressure and heart rate were not significant after unilateral nephrectomy. When the maximal MRNA due to dimethylphenylpiperazinium iodide (DMPP) administration was set as 100%, relative basal MRNA at 3, 7, 14 and 28 days were estimated in sham and nephrectomy groups. Also, relative basal MRNA increased about two times in nephrectomy group. After unilateral nephrectomy, the remaining kidney weight per unit body weight increased significantly by 18-35%. These findings indicate that the RNA in the remaining kidney was reflexly inhibited by the activation of afferent input due to ligation of renal vessels, ureter and nerves under acute nephrectomy. Under chronic unilateral nephrectomy, basal MRNA and the weight of the remaining kidney were increased significantly. The RNA per unit of kidney weight in unilateral nephrectomized rats was increased at 3 and 7 days and then it was relatively constant at 14 and 28 days.

Action Potentials↗
PubMed1997

Treatment of bronchial stricture due to endobronchial tuberculosis.

Between 1974 and 1995 we encountered 19 cases of bronchial stricture or obliteration caused by endobronchial tuberculous lesions. In 11 the involvements were located at the right bronchus (including involvements of segmental and middle lobe bronchi) and in 8 at the left bronchus. On bronchoscopic biopsy of the stenosed bronchus, 7 patients showed histopathologic findings of tuberculous bronchitis, but 12 patients showed nonspecific inflammatory granular tissue. Five patients were kept under conservative observation because of mild subjective symptoms or refusal to undergo operation. Two patients underwent stent procedures but had poor outcomes. Twelve patients underwent operation. As the bronchial lesions in four of them were confined to the lobar or segmental bronchus, lobectomy was performed. One patient with a history of infantile tuberculosis had developed complete obliteration of the left main bronchus and cystic bronchiectasis in the entire lung parenchyma; pneumonectomy was essential. Seven patients who had strictures involving the main bronchus underwent bronchoplastic surgery with right (n = 4) or left (n = 3) upper sleeve lobectomy. None of the patients treated surgically showed any postoperative complication or recurrence of the tuberculosis. These surgical results for endobronchial tuberculosis indicate the need for early detection and operation. Bronchoscopy and computed tomography are the methods of choice for accurate diagnosis of bronchial involvement and assessment of the surgical indications. It is emphasized that bronchoplastic surgery is the best treatment for bronchial stricture involving bilateral main bronchi.

Adult↗
PubMed1997

Experimental acute glomerulonephritis induced in the rabbit with a specific streptococcal antigen.

FITC-labelled IgG obtained from patients convalescing from acute poststreptococcal glomerulonephritis (APSGN) stains glomeruli of patients with early APSGN. We previously reported a streptococcal antigen (preabsorbing antigen (PA-Ag)) that preabsorbed the stain out of sera from the convalescent patients and thus prevented glomerular staining. To confirm the nephritogenicity of PA-Ag, we administered up to 40 mg of this antigen to rabbits for 8 days and observed them for up to 9 weeks. Immunohistological analysis showed diffuse and global glomerular staining for C3 without notable staining for gamma-globulin. Light microscopic examinations revealed slight to moderate proliferative glomerulonephritis with exudative change. Control rabbits, which received similar doses of bovine serum albumin, did not show significant staining for C3. A transient and significant decrease in CH50 was observed from weeks 3 to 7 (9.7 +/- 0.3 U/ml at week 3; normal range 12.9 +/- 0.6 U/ml). This experimental model showed a resemblance to immunological and immunohistological features of APSGN in humans. Although the precise mechanisms are yet to be determined, complement activation by PA-Ag seems to hold a key position in this model and in the human disease.

Acute Disease↗
PubMed1997

The role of I-Ag7 beta chain in peptide binding and antigen recognition by T cells.

We examine here how the beta chain of the class II MHC molecule I-Ag7 influences T cell recognition. Three sets of T cell clones were identified. The first set recognizes peptides bound to I-Ag7, I-Ad and I-Ag7 mutant in which the allele-specific residues His and Ser at position 56 and 57 were changed to the Pro at residue 56 and to non-polymorphic Asp at residue 57. The second set responds to the antigen presented only by I-Ag7 and does not recognize the peptides bound to the other class II molecules. The third set is also specific for I-Ag7 as a result of the poor binding of the peptide to I-Ad and the mutant I-Ag7. These results indicate that positions 56 and 57 of the I-Ag7 class II MHC beta chain play a role in both T cell recognition of the MHC-peptide complex and peptide binding to MHC. These two different functions may be involved in I-Ag7-restricted beta cell antigen recognition by diabetogenic T cell clones.

Animals↗
PubMed1997

Mechanism of constant contractile efficiency under cooling inotropy of myocardium: simulation.

We have reported that, in canine hearts, cardiac cooling to 29 degrees C enhanced left ventricular contractility but changed neither the contractile efficiency of cross-bridge (CB) cycling nor the excitation-contraction coupling energy. The mechanism of this intriguing energetics remained unknown. To get insights into this mechanism, we simulated myocardial cooling mechanoenergetics using basic Ca2+ and CB kinetics. We assumed that both adenosinetriphosphatase (ATPase)-dependent sarcoplasmic reticulum (SR) Ca2+ uptake and CB detachment decelerated with cooling. We also assumed that all the ATPase-independent SR Ca2+ release, Ca2+ binding to and dissociation from troponin, and CB attachment remained unchanged. The simulated cooling shifted the CB force-free Ca2+ concentration curve to a lower Ca2+ concentration, increasing the Ca2+ responsiveness of CB force generation, and increased the maximum Ca(2+)-activated force. The simulation most importantly showed that these cooling effects combined led to a constant contractile efficiency when Ca2+ uptake and CB detachment rate constants changed appropriately. This result seems to account for our experimentally observed constant contractile efficiency under cooling inotropy.

Adenosine Triphosphatases↗
PubMed1997

Simultaneous lung and liver resection for primary pulmonary leiomyosarcoma.

We report on a patient with primary pulmonary leiomyosarcoma and hepatic metastasis who was treated successfully with a single-stage surgical operation. As a cure for primary pulmonary leiomyosarcoma has only been achieved by surgical resection, primary radical treatment should be considered, even in advanced cases having distant metastases which are expected to be resectable.

Humans↗
PubMed1997

Changes in blood coagulation, platelet aggregation, and lipid metabolism in rats given lipids containing docosahexaenoic acid.

In order to identify an adequate intake level of docosahexaenoic acid (DHA), changes in various parameters related to health benefits were studied in rats fed on diets containing 10% test lipids at different n-3(DHA)/n-6 ratios for two weeks. An evaluation of the critical level of the dietary n-3/n-6 ratio which had a significant effect on the parameters of several tissues indicated that the response to the dietary ratios differed according to the parameter, the variation in ratio ranging approximately from 0.20 to 1.77 with either a positive or negative effect on the health benefit. These results suggest that a suitable intake level of DHA would be within this range. In view of safety, however, the critical level for the dietary n-3/n-6 ratio may be around 0.56, as shown by a detailed analysis on the lower limit level of the harmful parameters. We thus propose that the dietary intake of DHA should not be more than 0.56 in terms of the n-3/n-6 ratio.

Animals↗
PubMed1997

Ryanodine decreases internal Ca2+ recirculation fraction of the canine heart as studied by postextrasystolic transient alternans.

We tested our hypothesis that the O2 wasting of Ca2+ handling in the excitation-contraction (E-C) coupling in ryanodine-treated failing hearts could be reflected by a decrease in the internal Ca2+ recirculation fraction (RF). We have reported, using canine excised cross-circulated hearts, that intracoronary ryanodine (40 nmol/l blood) halved left ventricular contractility without decreasing myocardial O2 consumption for the E-C coupling. We previously suspected this mechanoenergetic state to manifest energy wasting of Ca2+ handling due to ryanodine causing leakage of Ca2+ from the sarcoplasmic reticulum. To test this hypothesis, we analyzed all the sporadic spontaneous cases of postextrasystolic potentiation (PESP) obtained during the ryanodine experiments. We calculated RF from the beat constant of the exponential decay component of not only the monotonic type but also the transient alternans type of PESP. Results showed that ryanodine significantly decreased the beat constant in both types of PESP from about 2 to 1.5 beats and hence RF from 0.6 to 0.5 on the average, supporting the hypothesis. This organ-level systems approach to Ca2+ handling using transient alternans PESP as well as monotonic PESP may help obtain better insights into the mechanoenergetics of failing hearts.

Animals↗
PubMed1997

[Chondroblastoma of the temporal bone: a case report].

A 30-year-old male had been suffering from left temporalgia of six months duration and then developed left hearing disturbance. Craniogram and bone window CT revealed a well defined osteolytic lesion in the left temporal bone. CT scan showed an expansile heterogenous mass with calcification. Both T1 and T2 weighted MRI demonstrated a well lobulated mixed intensity mass, but no evidence of dural or intracranial invasion. The tumor exhibited homogenous enhancement on CT and MRI. Angiogram revealed a well marked staining supplied by the left middle meningeal and deep temporal arteries. Subtotal removal of the tumor was carried out with cranioplasty. Histologically, this tumor was composed of round or polygonal chondroblasts, scattered osteoclast-like giant cells with a foci of cartilage in the stroma. Many reports describe giant cell tumor can be differentiated by immunohistochemical demonstration of S100 protein. Although in our case, histological findings simulated those of eosinophilic granuloma, it was diagnosed as chondroblastoma because of the foci of cartilage in the stroma. Because this tumor is usually benign, recurrence of the tumor is rare after surgical resection. Post-operative irradiation has been reported to be effective in decreasing the recurrence of the tumor. But it should be carefully observed because of possible sarcomatous change in such tumors.

Adult↗
PubMed1997

Effects of acute arterial bleeding on renal sympathetic nerve activity in young and old anesthetized rats.

We compared the change in renal sympathetic nerve activity (RNA) during hemorrhage in young and old rats. Young (10 weeks) and old (80 weeks) male Wistar rats were anesthetized, and RNA together with arterial pressure (AP) and heart rate (HR) were measured under spontaneous respiration. Acute arterial bleeding, 1ml/100g body weight, was carried out to induce hypotension and hypovolemia. With bleeding, mean AP (MAP) decreased from 110 +/- 12 to 23 +/- 11mmHg (mean +/- SEM) and from 93 +/- 15 to 15 +/- 6mmHg in young and old rats, respectively. The difference in the change of MAP between the young and old rats was not significant. With bleeding, mean RNA increased by 46 +/- 21% and 20 +/- 16% in young and old rats, respectively. The increase in mean RNA of the old rats was significantly lower than that of the young rats. We estimated the gain of the baroceptor-renal sympathetic nervous system by using the formula delta RNA/RNA/delta MAP/MAP. The gain was 0.61 +/- 0.34 and 0.23 +/- 0.18 in young and old rats, respectively. The difference in the gain was statistically significant (p < 0.05). We concluded that the gain of baroceptor-sympathetic nerve system in acute arterial hemorrhage is attenuated with aging.

Aging↗
PubMed1996

The class II MHC I-Ag7 molecules from non-obese diabetic mice are poor peptide binders.

The class II molecules of the diabetes-prone NOD mice, I-Ag7, showed very limited amounts of stable form when analyzed by SDS-PAGE. We included the analysis of spleen B cells and B lymphoma cells transfected with I-Ag7 genes. Early during bio-synthesis there was invariant chain binding to the alpha beta-chains. Examination of APCs from F1 mice (NOD x C57BL/6) indicated that the same APC expressed high levels of unstable I-Ag7 and normal amounts of stable class II molecules compared with the other haplotype (I-Ab). The half-life of I-Ag7-peptide complexes on the cell surface of APC was significantly shorter than that of other class II haplotypes. Direct biochemical demonstration of peptide interactions with I-Ag7 was difficult to demonstrate. In T cell assays, the immunogenic peptides, including the diabetogenic Ag, were rapidly lost when peptide-pulsed APCs were washed free of peptide. We hypothesize that the weak and unstable peptide-binding property of I-Ag7 molecules does not favor the elimination or inactivation of autoreactive T cells.

Amino Acid Sequence↗
PubMed1996

Comparison of pleuropneumonectomy and limited surgery for lung cancer with pleural dissemination.

The role of surgery in the management of lung cancer with pleural dissemination is controversial. We performed a retrospective analysis of our patients with lung cancer and pleural dissemination who were treated surgically. Between 1973 and 1993, 1,206 patients with lung cancer underwent pulmonary resection at Kanazawa University Hospital. Among them, 40 (3.3%) had pleural dissemination without pleural effusion. The 1-, 3-, and 5-year survival rates for 38 patients (except 2 patients undergoing exploratory thoracotomy alone) were 51.5%, 19.4%, and 19.4%, respectively. The 1-year survival rate in the 10 patients who underwent pleuropneumonectomy was only 20%, and 9 of these patients died within 18 months postoperatively (1 patient has survived for 25 months). In contrast, the 1-, 3-, and 5-year survival rates for the 14 patients who underwent resection of the primary tumor plus parietal pleurectomy were 85.1%, 35.5%, and 35.5%, respectively, a significantly better outcome (P < 0.01). Seven patients are still alive (the longest survival time is 65 months with the disease). The average survival time in the seven fatal cases was 18 months. In patients with lung cancer accompanied by pleural dissemination, it is quite possible that local excision plus pleurectomy will be justified.

Adenocarcinoma↗
PubMed1996

Experimental sensory neuropathy induced by sensitization with ganglioside GD1b.

Three of six rabbits immunized with purified GD1b developed ataxic sensory neuropathy. They laid on the floor with their limbs splayed out, and their movements were awkward; but muscle power, tonus, and superficial sensation appeared to be intact. Sciatic nerve motor conduction studies were normal. Axonal degeneration was present in the dorsal column of the spinal cord, in the dorsal roots, and in the sciatic nerve. Some of the nerve cell bodies in the dorsal root ganglia had degenerated and disappeared. No demyelinative lesions or mononuclear cell infiltrations were seen in those regions. No pathological changes were present in the other three immunized rabbits that showed no clinical symptoms. Control rabbits inoculated only with adjuvants showed neither clinical symptoms nor pathological changes. Anti-GD1b antibody was raised in the sera from all six rabbits immunized with GD1b. The monoclonal anti-GD1b antibody GGR12 immunostained about one-half the rabbit primary sensory neurons. Sensitization with GD1b, therefore, may cause ataxic sensory neuropathy in rabbits due to antibody-mediated damage to the primary sensory neurons.

Animals↗