Biomedical subjects

K Kuwata

Publications and source records attributed to K Kuwata.

At least 19 recordsLinked to original sources

PubMed1999

The characterization of human brain tumor using magnetization transfer technique in magnetic resonance imaging.

The clinical applicability of magnetization transfer (MT) technique in magnetic resonance imaging (MRI) for the estimation of the histological and constitutional feature of brain tumors was investigated. MT effect was evaluated by measuring the MT ratio (MTR). The parameters in 1.5-tesla MRI system were as follows: TR, 50 msec; TE, 5 msec; flip angle, 30 degree; offset frequency of off-resonance MT pulse, 1000 Hz. The sequence was performed in 20 normal volunteers and 45 patients with brain tumors which were characterized histologically and surgically. The MTR for brain tumors was significantly lower than that for normal brain tissue (p < 0.05). The MTR for meningioma was higher than that for the other brain tumors (p < 0.05). In the meningiomas, MTR for fibrous type was higher than that for meningothelial type, but there was no statistical significance. Regarding the physical consistency for the brain tumors, as classified by surgery, there was a statistically significant difference in MTR between the soft tumor group (0.22 +/- 0.03, n = 6) and the hard tumor group (0.36 +/- 0.04, n = 10) (p < 0.01). This study suggested that the MT technique for patients with brain tumor may be useful to understand the characteristics of the tumors presurgically, based on the degree of intermolecular interaction of macromolecule such as protein.

Adenoma↗

PubMed1999

Investigation of slow dynamics of the sulfhydryl in the solution and gel states of bovine serum albumin: A vector electron paramagnetic resonance study.

Serum albumin has one reactive sulfhydryl (Cys-34) that is one of the important binding sites. Cys-34 is located in the crevice on the surface of the albumin molecule and is therefore restricted in its motion. Bovine serum albumin (BSA) Fraction V forms a transparent gel at pD 4.0 (F-form) in D2O at protein concentrations above 7% (BSA*-gel). We studied the molecular motion of Cys-34 on BSA in the solution and gel states by the vector electron paramagnetic resonance (EPR) method using a maleimide spin label. The rotational correlation times of the spin label bound to Cys-34 in the BSA solution and BSA*-gel were in the order of 10(-6) and 10(-5) s, respectively. A longer rotational correlation time of the Cys-34 spin label in the BSA*-gel suggested that the gel network formed in BSA may drastically slow the motion of Cys-34. The integrated value obtained from the vector EPR spectra also showed an extremely dramatic slowing of the Cys-34 spin label during the gel formation. On the other hand, the values for order parameter and the inclination of the principal axis (z) of the Cys-34 spin label to the rotational axis (mu) were the same in the BSA solution and BSA*-gel.

Animals↗

PubMed1998

alpha-->beta transition of beta-lactoglobulin as evidenced by heteronuclear NMR.

Whereas bovine beta-lactoglobulin is a predominantly beta-sheet protein, it has a marked alpha-helical preference and can be considered to be a useful model of the alpha-->beta transition, a key issue for understanding the folding and biological function of a number of proteins. In order to understand the mechanism of the alpha-->beta transition, the backbone structures of the recombinant bovine beta-lactoglobulin A in the native state and in the highly helical state induced by 2,2,2-trifluoroethanol were characterized by 1H, 13C and 15N multidimensional NMR spectroscopy. Overall, the secondary structures in the native state were similar to those of the crystal structure. On the other hand, beta-lactoglobulin in the 2,2,2-trifluoroethanol state was composed of many alpha-helical segments. The presence of the persistent alpha-helices in the helical state and the core beta-sheet in the native state suggested that during folding native-like core beta-sheet and several non-native helices are formed first and the remaining beta-sheet is subsequently "induced" through interaction with the pre-existing beta-sheet.

Animals↗

PubMed1998

Knee and/or hip joint destruction in rheumatoid arthritis is associated with HLA-DRB1*0405 in Japanese patients.

To determine the prognostic factors for knee and/or hip joint destruction in rheumatoid arthritis (RA) patients, we typed 379 RA patients for HLA-DRB alleles and analysed the antigen frequencies. The DRB1*0405 antigen frequency in RA patients who underwent total knee replacement and/or total hip replacement was significantly higher than in those who did not have replacements, which meant that DRB1*0405 was associated with knee and/or hip joint destruction. This finding may be of value for predicting knee and/or hip joint destruction in RA.

Adolescent↗

PubMed1998

[Mediastinal bronchogenic cyst associated with high serum level of CA19-9--a surgical case report].

We reported a case of mediastinal bronchogenic cyst in a patient with a high serum level of CA19-9. The patient, a 41-year-old man, presented with a complaint of persistent fever. Chest X-ray examination, computed tomography and magnetic resonance imaging showed a subcarinal mass shadow which was diagnosed preoperatively as a bronchogenic cyst. The serum level of CA19-9 was 73 U/ml. The cyst was partially removed via right thoracotomy. Histopathological findings were compatible with bronchogenic cyst. The CA19-9 level in the specimen was 134,00 U/ml. The serum level of CA19-9 decreased to normal postoperatively. The postoperative course was uneventful.

Adult↗

PubMed1998

[Mediastinoscopic diagnosis and drainage of pericardial diverticulum--a case report].

A 38-year-old male was suspected of having an enlarged pretracheal lymph node on chest CT scan. At mediastinoscopy, a cystic lesion was recognized, and showed repeated dilatation and contraction synchronously with the cardiac beat. Pneumopericardium was demonstrated by intraoperative pneumocystography. The cystic lesion was diagnosed as pericardial diverticulum. The diverticular wall was partially resected for drainage of the pericardial fluid. Mediastinoscopy as a less invasive procedure may be useful for the differential diagnosis of adenopathies, and in case of lesion such as a small pericardial diverticulum may allow treatment.

Adult↗

PubMed1998

[A successfully treated case of empyema with a large tracheal fistula after subtotal esophagotomy by mediastinoscopy].

We reported a successfully treated case of empyema with a large tracheal fistula after subtotal esophagotomy. This 59-year-old male was treated by drainage with mediastinoscopy and repeated wash-out under bronchoscopy, because we could not use the omentum and he was the poor-risk patient. The trancheal fistula was obliterated bronchoscopically, 4 months after the mediastinoscopy. We believe that this method (abscess drainage with mediastinoscope and wash-out repeatedly) is useful for those who has broncheal fistula after esophagectomy.

Bronchial Fistula↗

PubMed1998

[Mediastinoscopic drainage for descending necrotizing mediastinitis].

A case of descending necrotizing mediastinitis that was treated by mediastinoscopic drainage is reported. The patient was a 56-year-old diabetic woman. A hypopharyngeal abscess extended to the mediastinum through the neck. No septic condition was noted. Chest CT showed that the abscess reached 4 cm below the tracheal bifurcation. Pus was drained under direct observation by mediastinoscopy, and a drain was placed in an appropriate position. After operation, lavage was performed through the drain, and cure was achieved on the 42nd postoperative day. This technique should be considered as surgical treatment for descending necrotizing mediastinitis in the absence of serious complication such as sepsis, because it has a more reliable drainage effect than the conventional transcervical method, and because it is less invasive than thoracotomy.

Drainage↗

PubMed1998

Role of Helicobacter pylori in residual gastritis after distal partial gastrectomy.

We studied the relation between Helicobacter pylori and residual gastritis in 28 patients with gastric cancer on whom distal partial gastrectomy with Billroth I reconstruction was performed over a 13-month period. They were subjected to serologic testing along with endoscopic and histologic examinations before operation and at 3, 6, and 12 months after operation. Anti-H. pylori immunoglobulin G (IgG) and serum gastrin levels were measured by serologic tests. The presence or absence of gastritis was determined endoscopically, and gastric mucosal hexosamine levels were determined. Gastritis was measured quantitatively by histologic examination in specimens taken from the gastric mucosa using Rauws' score. After the initial histologic evaluation we divided the H. pylori-positive patients into two groups: those with a Rauws' score of 0 to 3 ("weak" gastritis group), and those with a Rauws' score of 4 to 10 ("strong" gastritis group), allowing us to compare the results of our three postoperative histologic examinations of the two groups for possible significant differences. Our endoscopic examinations showed gastric mucosal inflammatory changes in both H. pylori-positive and H. pylori-negative patients at 3, 6, and 12 months after operation, but there was no significant difference between these two groups at any point. During the histologic examinations, however, anti-H. pylori IgG assay had become negative in several patients in the "weak" gastritis group at 3 months after operation and was found to have become negative in 78% of all patients in that group 12 months after operation. In contrast, in the "strong" gastritis group H. pylori infection was still evident in the patients 12 months after operation, suggesting that "strong" histologic gastritis may have some connection to H. pylori infection, whereas "weak" histologic gastritis has no such connection. The gastric mucosal hexosamine level was higher in the "weak" gastritis group than in the "strong" gastritis group both before operation and at 6 and 12 months, indicating some relation between gastric inflammatory changes and hexosamine levels in gastric mucosa. It further suggested the possibility that H. pylori plays a role in destroying gastric mucosa by depleting mucin, thus acting as one (though not the only) cause of residual gastritis after distal partial gastrectomy. In conclusion, we found evidence that there is a relation between residual gastritis and H. pylori infection, but H. pylori is not the sole cause of residual gastritis after gastric surgery. A causal relation is difficult to detect by simple analysis of histologic findings or by endoscopic observation or clinical symptoms alone.

Female↗

PubMed1998

Chest wall repair with a titanium instrument.

We performed chest wall repair with titanium alloy instruments as artificial ribs for prevention of paradoxical respiration and protection of the lung and liver after chest wall resection including the nearly entire length of the right seventh to the eleventh ribs and the costal arch for metastasis of osteosarcoma. The technique of this operation is presented diagrammatically.

Adolescent↗

PubMed1998

Clinical applicability of functional magnetic resonance imaging and activation study with single photon emission computerized tomography for functional mapping.

The purpose of this study is to estimate the clinical applicability of functional magnetic resonance imaging (f-MRI) combined with the activation study using single photon emission computerized tomography (SPECT) with special reference to identification of primary sensorimotor area. Five healthy volunteers and 5 patients with brain tumors located around the sensorimotor cortex were studied by both f-MRI with gradient echo and SPECT with 99mTc-ethyl cysteinate dimer using split-dose and subtraction method. In f-MRI study, the significant activation of the sensorimotor area was observed in all subjects. Various concurrent activation regions such as supplementary motor (2 volunteers vs. 4 patients), premotor (1 vs. 2) and ipsilateral sensorimotor area (1 vs. 2) were also observed. In the cases with the activation of neighboring regions of sensorimotor area, it was difficult to identify the area in f-MRI. In SPECT study, the sensorimotor area was depicted as the most increased area in regional cerebral blood flow in eight cases, the characteristics of which were helpful to diagnose the area, while significant activation of the area with edema could not be detected in two patients. Consequently, the sensorimotor area was cross-validated with both the modalities. This study demonstrated that it would be valuable to use both techniques for the clinical assessment of the sensorimotor area.

Adult↗

PubMed1998

Pulsed off-resonance magnetization transfer for brain tumor in patients.

We investigated the clinical applicability of pulsed off-resonance magnetization transfer (MT) technique in magnetic resonance (MR) imaging for the estimation of the histological feature of brain tumor. The parameters were optimized using bovine serum albumin (BSA) solutions and gels in 1.5-tesla MR system as follows: TR, 50 msec; TE, 5 msec; flip angle, 30 degree; offset frequency, 1000 Hz. MT effect was evaluated by measuring the MT ratio (MTR) and reconstructing calculated MTR color image. The MTRs of the BSA solutions and gels increased with increasing concentrations of protein, while the MTRs of the gels were remarkably higher than those of the solutions. The optimized sequence was performed in 20 healthy volunteers and 30 patients with brain tumors. In normal brains, the MTRs were significantly higher in white matter than in gray matter (p < 0.05). The MTR in brain tumor was significantly lower than that in normal brain tissue (p < 0.05) and the calculated MTR image produced contrast between brain tumor and normal brain tissue. There was a statistically significant difference in MTR between benign (0.30 +/- 0.05, n = 17) and malignant (0.26 +/- 0.04, n = 13) tumors (p < 0.05). The optimized MT technique is quite sensitive for estimating the degree of intermolecular interaction between macromolecules and water within the central nervous system.

Brain Neoplasms↗

PubMed1998

[Correlation between pyrimidine nucleoside phosphorylase (PyNPase)/platelet-derived endothelial cell growth factor and histological prognostic factor, and influences of 5'-deoxy-5-fluorouridine (5'-DFUR) administration on PyNPase levels. 5'-DFUR Joint Research Group in the Osaka Area for Gastric Cancer].

PURPOSE: Pyrimidine nucleoside phosphorylase (PyNPase), among which thymidine phosphorylase (dThdPase) exists mainly in human tumor tissues, is an enzyme to convert 5'-deoxy-5-fluorouridine (5'-DFUR) to 5-fluorouracil. Recently, it was reported that dThdPase was identical to platelet-derived endothelial cell growth factor, angiogenetic factor. Therefore, we expect that there is possibility of dThdPase being a prognostic factor. METHODS: We investigated for a possible correlation between PyNPase activities in tumor tissues and prognostic factors of histological findings, examined the influences of preoperative oral 5'-DFUR administration to PyNPase levels and investigated for a correlation between HPLC methods and ELISA methods in patients with gastric cancer. RESULTS: Higher levels of PyNPase were observed in patients with advanced t,n,v, and ly factors. PyNPase levels decreased by 5'-DFUR in patients with differentiated cases. A high correlation was found between HPLC and ELISA methods. CONCLUSION: This study suggests that we must investigate possibility of PyNPase being a prognostic factor in more detail.

Antineoplastic Agents↗

PubMed1997

Enhanced myosin light chain phosphorylations as a central mechanism for coronary artery spasm in a swine model with interleukin-1beta.

BACKGROUND: Although coronary artery spasm plays an important role in a wide variety of ischemic heart diseases, the intracellular mechanism for the spasm remains to be clarified. We examined the role of myosin light chain (MLC) phosphorylations, a key mechanism for contraction of vascular smooth muscle, in our swine model with interleukin-1beta (IL-1beta). METHODS AND RESULTS: IL-1beta was applied chronically to the porcine coronary arteries from the adventitia to induce an inflammatory/proliferative lesion. Two weeks after the operation, intracoronary serotonin repeatedly induced coronary hyperconstrictions at the IL-1beta-treated site both in vivo and in vitro, which were markedly inhibited by fasudil, an inhibitor of protein kinases, including protein kinase C and MLC kinase. Western blot analysis showed that during serotonin-induced contractions, MLC monophosphorylation was significantly increased and sustained in the spastic segment compared with the control segment, whereas MLC diphosphorylation was noted only in the spastic segment. A significant correlation was noted between the serotonin-induced contractions and MLC phosphorylations. Both types of MLC phosphorylation were markedly inhibited by fasudil. In addition, MLC diphosphorylation was never induced by a simple endothelium removal in the normal coronary artery, whereas enhanced MLC phosphorylations in the spastic segment were noted regardless of the presence or absence of the endothelium. CONCLUSIONS: These results indicate that enhanced MLC phosphorylations in the vascular smooth muscle play a central role in the pathogenesis of coronary spasm in our swine model.

Animals↗

PubMed1997

Vasculoprotective role of inducible nitric oxide synthase at inflammatory coronary lesions induced by chronic treatment with interleukin-1beta in pigs in vivo.

BACKGROUND: We recently developed a porcine model in which chronic, local treatment with interleukin-1beta (IL-1beta) causes coronary arteriosclerotic changes and hyperconstrictive responses. Inflammatory cytokines are known to induce inducible NO synthase (iNOS) in the vascular smooth muscle. This study was designed to examine whether or not the production of NO by iNOS has a protective or deleterious effect on the coronary artery in vivo. METHODS AND RESULTS: A segment of the porcine coronary artery was aseptically wrapped with cotton mesh absorbing IL-1beta suspension. We inhibited both eNOS and iNOS activity by cotreatment with L-NAME (a nonspecific inhibitor of NOS) and iNOS activity alone by aminoguanidine (a selective inhibitor of iNOS). Immunostaining showed that iNOS was absent in the normal coronary artery, whereas it was highly expressed 1 day after the application of IL-1beta and thereafter downregulated until 14 days. In contrast, eNOS was well maintained throughout the study period. Two weeks after the operation, hyperconstrictive responses to intracoronary serotonin and neointimal formation were noted at the IL-1beta-treated site, and both responses were significantly greater at the site cotreated with either L-NAME or aminoguanidine. CONCLUSIONS: These results indicate that iNOS is transiently induced in vivo in response to local inflammation and that NO produced by iNOS exerts an inhibitory effect against the cytokine-induced proliferative/vasospastic changes of the coronary artery in vivo.

Animals↗

PubMed1997

Alteration of redox state of human serum albumin in patients under anesthesia and invasive surgery.

Human serum albumin is a mixture of mercapt- (HMA, reduced form) and nonmercaptalbumin (HNA, oxidized form). We studied the mercapt<-->nonmercapt conversion of human serum albumin, which reflects the redox state of the extracellular fluids, in cardiac and other common surgical_ patients using high-performance liquid chromatography. Mean values of [(HMA)/(HMA+HNA)]+/-standard deviation, fHMA+/-sigma], for patients who received common surgery (group 1) and cardiac surgery (group 2) at the start of anesthesia were 0.636+/-0.050 (n = 83) and 0.615+/-0.062 (n = 14), respectively. fHMA values were markedly lower than those for healthy male adults of 0.750+/-0.028 (n = 28). fHMA values increased at 24 h after the start of anesthesia and decreased on the 4th postoperative day in most of the patients. These postoperative changes were prominent in cardiac surgical patients. Although fHMA values after the 7th postoperative day recovered to those at the start of anesthesia in almost all of common surgical patients, those in cardiac surgical patients never recovered even on the 21st postoperative day.

Adult↗

PubMed1997

Rotational correlation times of internuclear vectors in a DNA duplex with G-A mismatch determined in aqueous solution by complete relaxation matrix analysis of off-resonance ROESY (O-ROESY) spectra.

Complete relaxation matrix analysis of the off-resonance ROESY (O-ROESY) spectra is presented and demonstrated for a synthetic DNA duplex with two G-A mismatches, d(GCTGTC-GAAAGC)2, in solution. The internuclear distance and the rotational correlation time of the internuclear vector could be garnered simultaneously using complete relaxation matrix analysis of O-ROESY, by which spin diffusion effects could be accommodated. Correlation times in the terminal and the mismatched regions were significantly reduced compared to those in other regions, indicating the conformational flexibility of the mismatched pair. The average structure obtained by restrained molecular dynamics simulation with inclusion of variations of the rotational correlation times also indicated a general tendency of the mismatched and contiguous bases to flip to the outside of the double strand. Off-resonance ROESY combined with the complete relaxation matrix analysis method may offer an alternative way to investigate the structures and dynamics of biological macromolecules.

DNA↗

PubMed1997

Mediastinoscopic extirpation of mediastinal ectopic parathyroid gland.

We report a case of a 50-year-old man with hyperparathyroidism secondary to chronic renal failure who underwent extirpation of a mediastinal ectopic parathyroid gland by a transcervical approach under mediastinoscopy. This procedure provides an excellent approach to the mediastinal ectopic parathyroid gland, and is less invasive than median sternotomy or thoracotomy.

Choristoma↗