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Biomedical subjects

S Sakai

Publications and source records attributed to S Sakai.

At least 865 records · Page 48Linked to original sources
PubMedDate not supplied

Assessment of left ventricular diastolic function with electrocardiography-gated myocardial perfusion SPECT: comparison with multigated equilibrium radionuclide angiography.

BACKGROUND: Technetium-labeled myocardial perfusion tracers allow the simultaneous assessment of myocardial perfusion and left ventricular function by electrocardiography (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT). This study evaluates left ventricular systolic and diastolic function by ECG-gated SPECT with the use of higher framing (32 frames per cardiac cycle) data acquisition. METHODS AND RESULTS: After receiving an injection of technetium 99m tetrofosmin, 48 patients with cardiac diseases were examined by ECG-gated myocardial perfusion SPECT with a 3-headed gamma camera. During gated data collection, 32 frames per cardiac cycle were acquired over 360 degrees in 60 steps, each of which consisted of 60 beats. Immediately thereafter, the 32 frames taken at each projection angle were combined into 16-frame and 8-frame data sets. Left ventricular end-diastolic volume (LVEDV, in milliliters), left ventricular end-systolic volume (LVESV, in milliliters), and left ventricular ejection fraction (LVEF, percentage) were automatically calculated from the 32-frame, 16-frame, and 8-frame gated data sets. Left ventricular time-volume curves from the 3 data sets were generated by Fourier curve fitting analysis with the use of 3 harmonics, and then peak filling rate (PFR, per second) was measured. Twenty-nine patients also underwent multigated equilibrium radionuclide angiography (ERNA) to determine the LVEF and PFR. Combining the 32-frame data into 16-frame and 8-frame data sets from the 48 patients generated a smaller LVEDV and a larger LVESV, and LVEF was significantly lower in accordance with the decreasing number of frames. Compared with ERNA studies (n = 29), the Bland-Altman method showed underestimated LVEFs and larger 95% limits of agreement in lower framing gated SPECT. CONCLUSIONS: Left ventricular functional parameters obtained from 32-frame gated SPECT correlated closely with those determined by ERNA studies. ECG-gated SPECT with 32-frame data can provide comprehensive information with which to evaluate many types of cardiac diseases.

Adult↗
PubMedDate not supplied

Control of molecular weight cut-off for immunoisolation by multilayering glycol chitosan-alginate polyion complex on alginate-based microcapsules.

Glycol chitosan is a positively charged polysaccharide which is water-soluble at pH 7.4, and is able to form a polyion complex (PIC) with anionic polymers, such as alginate. The authors attempt to develop a novel type of alginate-based microcapsule using this glycol chitosan for a islets-encapsulated bioartificial pancreas. The number of layers composed of glycol chitosan-alginate (GC-Alg) PIC were optimized, in order to cut off immunoglobulin transport and to protect encapsulated islets from the host immune reaction, and the transport characteristics were evaluated of glucose, bovine serum albumin (BSA) and gamma-globulin. To add mechanical stability to the microcapsule, calcium ions, which crosslinked the alginate polymers close to the interface between core Ca-alginate and multilayered membrane, were partially substituted with barium ions after the formation of multilayered Ca-alginate gel beads. The partition coefficients of BSA and gamma-globulin were decreased with the increasing number of layers. The immunoisolation was achieved against gamma-globulin with four layers of the GC-Alg PIC membrane, while BSA could permeate the membrane. The four-layered Ba-alginate gel bead had a good permeability for glucose, giving a diffusion coefficient corresponding to 80% of that in pure water. Insulin secretion from the islets in the four-layered Ba-alginate microcapsule was satisfactorily observed with the fractional stimulation ratio of 2.17. This result indicates that the encapsulated islets maintained their viability even after encapsulation. It was, thus, shown that the Ba-alginate microcapsule with four layers of the GC-Alg PIC membrane is promising as the microencapsulation material for a bioartificial pancreas.

Alginates↗
PubMedDate not supplied

A skeletal muscle actuator for an artificial heart.

The authors developed a system to use skeletal muscle as an artificial heart actuator. This system consists of a flexible rod, sheath, crank, and cam to transmit the muscle power to a pusher plate pump and actuate it. The latissimus dorsi muscle was dissected at the lower ribs, and its end was connected with the flexible rod. The contraction of skeletal muscle was linearly transmitted, with the rod introduced inside the sheath, to the pump. The whole system was implanted in dogs (14-18 kg) and pump performance was evaluated with a mock circulatory system (preload = 10 mmHg, afterload = 75 mmHg). In these experiments, the pump output was maintained at 0.8 to 2.0 L/min (60 bpm) for 200 min, with a non-preconditioned muscle that was stimulated continuously. The output obtained was 2.5 mW/gram. Efficiency of this system was about 50% of the muscle power available. When the muscle was stimulated intermittently every 30 min, pump flow was maintained at > 0.8 L/min for 20 hr. Advantages of this system are: 1) the muscle power was linearly transmitted effectively, 2) this system could be installed with minimal surgery and without interruption in blood flow to the muscle, 3) the muscle is free from high intraventricular pressure that caused ischemia and, 4) the muscle can be set to the proper length in diastole to potentiate strong contractions.

Animals↗
PubMedDate not supplied

MR evaluation of intrapulmonary hematoma.

We report a case of circumscribed intrapulmonary hematoma, in which MR findings were useful in establishing the diagnosis. It is usually easy to make a diagnosis of intrapulmonary hematoma using conventional methods, when clinical history of trauma and regression of the mass can be observed on serial radiography. However, in this case the mass remained almost unchanged 4 months after trauma on chest radiography and CT. Magnetic resonance revealed a hyperintense mass with an even higher signal rim on T1-weighted imaging and an irregular hyperintense mass on T2*-weighted imaging. We made a diagnosis of pulmonary hematoma based on these MR findings. Follow-up chest radiography and CT taken 1 year after the injury, revealed a substantial decrease in the size of the mass, which confirmed the diagnosis. As in this case, some intrapulmonary hematomas regress very slowly or may even increase in size, and diagnosis can be difficult with conventional methods. In such cases, MRI can be helpful.

Adult↗
PubMedDate not supplied

Signal intensity characteristics of mediastinal cystic masses on T1-weighted MRI.

OBJECTIVE: We evaluated the intracystic MR signal intensity of mediastinal cystic masses to identify characteristic intensity patterns according to histologic type. MATERIALS AND METHODS: Magnetic resonance imaging was performed on 26 cystic mediastinal masses consisting of 8 thymic cysts, 5 bronchogenic cysts, 4 pericardial cysts, 5 cystic teratomas, and 4 cystic neurogenic tumors. Signal intensity ratios of each cyst to muscle were calculated on T1-weighted imaging. Surgical records were reviewed to document the presence of intracystic hemorrhage. Chemical analysis of intracystic fluid was performed in three cases. RESULTS: Bronchogenic cysts, cystic teratomas, and cystic neurogenic tumors had relatively high levels of signal intensities. Each pericardial cyst had a lower signal intensity than muscle. The signal intensities of thymic cysts were variable. Intracystic hemorrhage was present in 1 bronchogenic cyst, 2 cystic neurogenic tumors, 4 cystic teratomas, and 3 thymic cysts. No hemorrhage was found in any of the pericardial cysts. Sebaceous fluid was present in 1 cystic teratoma. CONCLUSION: The varying intensities of different cysts were considered to reflect the nature of the intracystic fluid. Since the nature of the fluid can reflect the histology to some extent, T1-weighted MRI will help to differentiate cystic mediastinal masses.

Bronchogenic Cyst↗
PubMedDate not supplied

Helical CT imaging of bronchial arteries with curved reformation technique in comparison with selective bronchial arteriography: preliminary report.

PURPOSE: Our goal was to evaluate the ability of helical CT to identify and demonstrate the origins and courses of bronchial arteries, using the curved reformation technique, in patients undergoing bronchial arterial interventional procedures. METHODS: Thin section helical CT was performed on seven patients before bronchial arterial interventional procedures. The curved reformation technique was used to demonstrate the origins and continuous vessel tracing of bronchial arteries and compared with bronchial arteriographic findings. RESULTS: In all, 16 bronchial arteries were evaluated, 8 on the right and 8 on the left. The origins of 12 bronchial arteries were identified. In the demonstration of tracing vessels, seven right bronchial arteries and three left were classified as excellent or fair. CONCLUSION: Helical CT imaging with the curved reformation technique is helpful in identifying bronchial arteries, especially on the right, in patients with indications for bronchial arterial interventional procedures.

Adult↗
PubMedDate not supplied

Patterns of peripheral enhancement in breast masses: correlation of findings on contrast medium enhanced MRI with histologic features and tumor angiogenesis.

PURPOSE: Our goal was to review patterns of peripheral enhancement on contrast-enhanced MRI of the breast and to correlate radiologic findings with pathologic features. METHOD: We reviewed the MR images of 124 consecutive women with breast lesions. Peripheral enhancement was identified in 35 (32 malignant, 3 benign) lesions. MRI findings were correlated with pathologic features including microvessel density and distribution determined histologically. RESULTS: Early peripheral enhancement with centripetal progression was seen in invasive carcinomas with a high peripheral and a low central microvessel density, associated with fibrosis and/or necrosis (n = 18; 15 with central fibrosis, 2 with fibrosis and necrosis, and 1 with necrosis alone). Early peripheral enhancement with minimal or no change in enhancement was seen in both malignant (n = 10) and benign (n = 3) lesions. Delayed peripheral enhancement with centrifugal progression was seen in carcinomas that had an expansive growth pattern and a high marginal vessel density with or without a vascularized rim of connective tissue (n = 4). CONCLUSION: Early peripheral enhancement with centripetal progression appears to be fairly specific for carcinomas, whereas early enhancement with minimal or no centripetal progression, although more common in malignant tumors, may be seen in some benign lesions as well.

Adult↗
PubMedDate not supplied

Bronchogenic carcinoma invasion of the chest wall: evaluation with dynamic cine MRI during breathing.

PURPOSE: Our goal was to assess the utility of breathing dynamic cine MR (BDCMR) in the evaluation of tumor invasion to the chest wall in bronchogenic carcinomas. METHOD: BDCMR imaging was performed preoperatively in 25 patients with bronchogenic carcinomas adjacent to the chest wall. Twelve sequential images were obtained in the same coronal and/or sagittal planes during one respiratory cycle with fast spoiled GRASS sequence, and analysis with cine-loop display was performed. RESULTS: In all 14 cases in which free movement of tumor along the parietal pleura on BDCMR was demonstrated, no chest wall invasion was evident at thoracotomy. However, of 11 patients with fixation of the tumor on BDCMR, 5 had benign pleural adhesions, 5 had chest wall invasion at thoracotomy, and 1 with an apical tumor had no benign pleural adhesion or chest wall invasion. CONCLUSION: Although BDCMR cannot distinguish benign pleural adhesions from chest wall invasion by tumor, this method accurately estimated the free movement of lung tumors with no invasion of chest wall from bronchogenic carcinomas prior to surgery.

Aged↗
PubMedDate not supplied

Bacteriologic studies on Neisseria gonorrhoeae isolated in Sapporo, Japan: investigation of beta-lactamase production and auxotypes.

The authors studied the annual incidence of isolation of penicillinase-producing Neisseria gonorrhoeae (PPNG) strains among the total number of strains of N. gonorrhoeae (1,401 strains) that were isolated in Sapporo, Japan during 1980-1989. During the first half of the 1980s, there was a tendency for PPNG to increase, and the peak incidence was 23.9% in 1985. Thereafter, the incidence of PPNG decreased to an isolation rate of 6.3% in 1989. In addition, the auxotypes of 592 of 1,401 isolated strains of Neisseria gonorrhoeae were studied during three periods: 1980-1985, 1986-1987, and 1988-1989. Among the 592 strains, 315 strains were tested for sensitivity to the action of amoxicillin. In the 1988-1989 period, the auxotype showed an increasing incidence of the auxotype that requires arginine, hypoxanthine, and uracil (i.e., AHU), whereas the proto- and pro-types decreased in incidence. The AHU strains showed higher sensitivity to amoxicillin administration compared with the proto- and pro-strains.

Amoxicillin↗
PubMedDate not supplied

Nucleolar organizer regions in human maxillary sinus squamous cell carcinoma.

A silver colloid technique for nucleolar organizer regions (AgNOR) was applied to paraffin sections of maxillary sinus squamous cell carcinomas (MSSCC) of 25 patients. The patients were divided into two groups, one with MSSCC recurring in the primary lesion after treatment with radiotherapy, chemotherapy and/or surgery and one without recurrence. Notable differences between the numbers of NOR in neoplastic epithelia and the normal mucosa were observed (P = 0.0001), but there were no differences between the numbers of NOR in the recurrent and non-recurrent carcinomas. This investigation found no prognostic importance in the number of AgNOR in MSSCC.

Aged↗
PubMedDate not supplied

Effect of DN-1417 on photosensitivity and cortically kindled seizure in Senegalese baboons, Papio papio.

The effect of DN-1417, a thyrotropin-releasing hormone (TRH) analogue, on photosensitivity and cortically kindled seizures was examined in seven Senegalese baboons (Papio papio). Intravenous (i.v.) administration of 2 mg/kg had no effect on either photosensitivity or cortically kindled seizures. When this agent was administered intracisternally, both the photomyoclonic response and cortically kindled seizures were suppressed for 4-5 days. A study of the transcallosal response also showed a long-lasting attenuation of the early positive wave (P1) amplitude (peak latency, 5-10 ms) elicited by a single stimulus after cisternal injection of DN-1417. These findings are consistent with the assumption that endogenous TRH is involved in suppression of epileptic seizures.

Animals↗
PubMedDate not supplied

N-Methyl-L-serine stimulates hyaluronan production in human skin fibroblasts.

We examined the effects of N-methyl-L-serine (NMS), an amino acid derivative, on hyaluronan (HA) synthesis in human skin fibroblasts. NMS (1-10 mM), but not L-serine, stimulated the incorporation of [(3)H]glucosamine into HA dose-dependently, with a maximum stimulation of 1.5-fold compared to the control. The effect of NMS was specific for HA production, because there was no change in sulfated glycosaminoglycan formation. Neither the N-methyl derivatives of L-glycine or L-alanine, nor N-methyl-D-serine, could stimulate HA synthesis, indicating that the beta-hydroxyl group and the L-configuration were essential for the activity. Gel filtration of the products showed that NMS stimulated the production of high-molecular-mass HA (>10(6) D) without affecting the production of low-molecular-mass HA. NMS required 24 h to stimulate HA production, and when fibroblasts were pretreated for 10-24 h with NMS (1-10 mM), membrane-associated HA synthase activity was increased dose-dependently. Thus, a second messenger is likely to be involved in the stimulation of HA production by NMS.

Amino Acids↗
PubMedDate not supplied

Synergistic effect of N-acetylglucosamine and retinoids on hyaluronan production in human keratinocytes.

Hyaluronan (HA) is well known to reside in the extracellular matrix as a water-sorbed macromolecule. The aims of this study were twofold: to investigate the regulation of HA synthesis in keratinocytes, and to develop a method to modulate this regulatory process. We found that N-acetylglucosamine (NAG) increased the production of HA by cultured keratinocytes dose dependently, but had no effect on the production by skin fibroblasts. The effect of NAG in keratinocytes was found to be specific for HA production, as there was no change in sulfated glycosaminoglycan formation. The copresence of NAG with either of two retinoids, retinoic acid (RA) or retinol, exerted a synergistic effect on HA production. To investigate whether human HA synthase (HAS) genes were regulated by NAG or retinoids, total RNA extracted from cells treated with these agents was subjected to Northern blot analysis. We observed that RA and retinol markedly induced the expression of HA synthase-3 (HAS3) mRNA. Moreover, beta-carotene, a provitamin A, influenced HA production and HAS3 gene expression in a manner similar to the retinoids. Conversely, NAG had no effect on the expression of HAS3 transcripts. Pretreatment of cells with RA stimulated the activity of membrane-associated HAS, whereas pretreatment with NAG did not. These results suggest that HA production is regulated by at least two pathways: one involving the regulation of HAS gene expression, and the other independent of such a regulatory effect. Taken together, our findings suggest that NAG is a new modulator of HA synthesis.

Animals↗
PubMedDate not supplied

Cytomegalovirus-induced gastritis in a bone marrow transplant patient.

Cytomegalovirus (CMV)-induced interstitial pneumonitis is a well-known lethal complication in bone marrow recipients. CMV is also known to cause gastroenteritis. We report the first case of a bone marrow recipient who developed CMV-induced gastritis which is verified both histologically and virologically. The gastritis preceded the interstitial pneumonitis which was detected in an early stage and was successfully treated. We propose that bone marrow recipients who show signs and symptoms of gastritis undergo an endoscopic examination, and that biopsied specimens should be scrutinized for CMV by both histological examination and culture investigation.

Bone Marrow Transplantation↗
PubMedDate not supplied

Cytomegalovirus pneumonitis occurring after allogeneic bone marrow transplantation: a study of 106 recipients.

We have followed 106 recipients of allogeneic bone marrow transplantation (BMT), and observed 47 episodes of interstitial pneumonitis (IP) in 37 patients. Cytomegalovirus (CMV) pneumonitis was seen in 18 episodes in 18 patients, of whom 10 patients were diagnosed by bronchoalveolar lavage (BAL), 7 patients by autopsy, and 1 patient by sputum culture. There was one varicella-zoster virus pneumonitis diagnosed by autopsy. However, we could find no apparent etiology of pneumonitis in the other 18 patients. The median interval between BMT and episodes of IP was 74 days (range, 23-578 days) for CMV pneumonitis, and 180 days (range, 41-428 days) for idiopathic pneumonitis (p less than 0.05). BAL was more sensitive than transbronchial lung biopsy in the diagnosis of CMV pneumonitis, and CD4/CD8 ratio in BAL fluid was inverted in all episodes of CMV pneumonitis. Computed tomography (CT) scans were performed in 31 episodes in 26 patients, and all scans revealed abnormalities. CT scans were more sensitive than routine chest X-rays against micro- or small-nodular patterns, air bronchogram, and air alveologram (p less than 0.05). CT scan and arterial blood gas analysis were most useful and necessary in approaching the problem of pneumonitis in allogeneic marrow transplant patients. Based on these findings, when CMV pneumonitis is suspected, it is recommended to perform BAL for the final diagnosis of CMV pneumonitis.

Adolescent↗
PubMedDate not supplied

Primary chondrosarcoma of the lung--a case report with immunohistochemical study.

A case of primary chondrosarcoma of the lung is presented. The tumor, located in the medial segment of the right lower lobe, was successfully resected surgically. Clinical survey did not reveal any primary lesion elsewhere. The tumor consisted of myxomatous, chondromatous, and fibrous lesions. Immunohistochemical study revealed that tumor cells were positive for S-100 protein and vimentin, and negative for other antisera which characterize epithelial tumors. With these clinical, histological, and immunohistochemical studies we diagnosed the tumor as a primary chondrosarcoma of the lung.

Aged↗
PubMedDate not supplied

A case with renal tubular damage: differentiation of Na reabsorption function by lithium clearance.

The recovery of the renal proximal and distal tubular sodium (Na) reabsorption was evaluated by analysis of the physiological metabolism of lithium reabsorbed by the renal tubules in a patient with toxic interstitial nephropathy. Administration of glucocorticoid facilitated the rapid recovery of the proximal tubular Na reabsorption (-0.63 to 3 mmol/min for 2 wk) followed by recovery of phosphate reabsorption (51 to 82% for 2 months). Distal Na reabsorption was not altered for 2 months. Although Li clearance has been previously performed in healthy volunteers, we could differentiate the recovery of the proximal and distal renal tubular function even in a diseased patient.

Absorption↗