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R Nakashima

Publications and source records attributed to R Nakashima.

At least 37 records · Page 2Linked to original sources
PubMed1996

Quantitative renography with the organ volume method and interporative background subtraction technique.

When quantification of renal activity is performed by planar imaging, many correction factors must be considered. To obtain quantitative renal images and renogram, we have examined our proposed method by using the organ volume for scatter, attenuation, and background activity, and the interporative background subtraction (IBS) technique in phantom and clinical studies. A renal phantom study was performed by varying the renal depth from 3 to 11 cm and the kidney-to-background activity concentration ratio from 5 to 80. Planar images were properly corrected for scatter, attenuation and background activity by our method and the corrected images were compared with the images obtained by the conventional method for the estimation of true renal activity. Clinical Tc-99m DTPA dynamic data for both a good and a poor renal function were also corrected by our method and volume-corrected renograms were obtained. For the phantom study, depth-independent images were obtained and these images gave a good estimation of the true count rate. In the clinical study, the conventional renogram was especially modified to allow for oversubtraction of background counts in the early phase (0-4 min). In conclusion, our proposed correction method can assess renal function qualitatively and quantitatively in both static and dynamic planar renal imaging.

Evaluation Studies as Topic↗
PubMed1996

[Evaluation of simultaneous acquisition of transmission and emission data on thallium-201 myocardial SPECT].

This study evaluates the usefulness of attenuation correction on regional myocardial tracer distributions defined by Thallium-201 myocardial SPECT images obtained from cardiac phantoms and patients with or without coronary heart disease. A three-detector SPECT system equipped with a Technetium-99m line source and a fan-beam collimator was used for simultaneous transmission and emission data acquisition. All three detectors were equipped with fan-beam collimators. Thallium-201 myocardial scintigraphy was performed on phantom study and 19 patients. Transmission images, uncorrected and corrected emission images were iteratively reconstructed with a EM-ML algorithm. Attenuation map computed from the transmission data was utilized for the attenuation correction. For the phantom study, circumferential profile analysis was applied to both datasets of horizontal long-axis slices through the center of the phantom. The maximum profile value in the circumferential profile set to 100% in the normalized uncorrected and corrected profiles. The uncorrected circumferential profiles from cardiac insert model 7070 and RH-2 cardiophantom showed decrease in activity in basal regions which appeared improvement in the attenuation corrected profiles. In clinical study, the inferior-to-anterior activity ratio, changed from 0.78 +/- 0.10 to 0.97 +/- 0.11 on stress images in patients with inferior ischemia and from 0.96 +/- 0.12 to 1.15 +/- 0.13 on 4 hour delayed or rest images in normal cases. The anteroapical wall of the attenuation corrected images, however, showed a decrease in activity relative to the inferior wall in normal cases. The increase in activity in inferior wall on attenuation corrected images was observed frequently in clinical study but not in phantom study. A presence of scatter from the liver or bowels may cause the increase in activity in the inferior wall in clinical study. In conclusion, transmission scan is one of the useful methods for the attenuation correction. Scatter correction, however, is also necessary to make an accurate attenuation corrected images.

Heart↗
PubMed1995

Structures of metal sites of oxidized bovine heart cytochrome c oxidase at 2.8 A.

The high resolution three-dimensional x-ray structure of the metal sites of bovine heart cytochrome c oxidase is reported. Cytochrome c oxidase is the largest membrane protein yet crystallized and analyzed at atomic resolution. Electron density distribution of the oxidized bovine cytochrome c oxidase at 2.8 A resolution indicates a dinuclear copper center with an unexpected structure similar to a [2Fe-2S]-type iron-sulfur center. Previously predicted zinc and magnesium sites have been located, the former bound by a nuclear encoded subunit on the matrix side of the membrane, and the latter situated between heme a3 and CuA, at the interface of subunits I and II. The O2 binding site contains heme a3 iron and copper atoms (CuB) with an interatomic distance of 4.5 A; there is no detectable bridging ligand between iron and copper atoms in spite of a strong antiferromagnetic coupling between them. A hydrogen bond is present between a hydroxyl group of the hydroxyfarnesylethyl side chain of heme a3 and an OH of a tyrosine. The tyrosine phenol plane is immediately adjacent and perpendicular to an imidazole group bonded to CuB, suggesting a possible role in intramolecular electron transfer or conformational control, the latter of which could induce the redox-coupled proton pumping. A phenyl group located halfway between a pyrrole plane of the heme a3 and an imidazole plane liganded to the other heme (heme a) could also influence electron transfer or conformational control.

Animals↗
PubMed1995

Loss of expression and loss of heterozygosity in the DCC gene in neoplasms of the human female reproductive tract.

In order to identify the possible role of the DCC gene in neoplasms of the human female reproductive tract, messenger RNA expression of the DCC gene was examined by reverse transcriptase-polymerase chain reaction, and expression of the DCC gene product was detected immunohistochemically. While histologically normal endometrium, cervical epithelium and ovary expressed detectable mRNA of the DCC gene, three of eight (37%) endometrial carcinomas, one of two (50%) cervical carcinomas and 9 of 22 (41%) ovarian malignant tumours had significantly reduced or negligible DCC expression, and another endometrial carcinoma and two other ovarian tumors underexpressed DCC when compared with histologically normal endometrial or ovarian tissues. Impaired DCC mRNA expression was detected more frequently in grade 3 ovarian epithelial tumours than in grade 1 tumours (P = 0.002). Loss of expression of the DCC gene product detected by immunohistochemistry significantly correlated with the loss of mRNA expression in ovarian carcinomas (P = 0.01 by chi-square test) or in both endometrial and ovarian carcinomas combined (P = 0.001). Loss of heterozygosity of the DCC gene was also evaluated by restriction fragment polymorphism analysis of the polymerase chain reaction-amplified DNA fragment. Loss of heterozygosity of the DCC gene was detected in one of seven (14%) informative cases of endometrial carcinomas, 1 of 11 (9%) informative cases of cervical carcinomas and two of six (33%) informative cases of ovarian tumours. These results demonstrate that inactivation of the DCC gene, especially by the loss of expression, plays a significant role in the aetiology of neoplasms of the human reproductive tract.

Adenocarcinoma↗
PubMed1995

Correlation of Tc-99m GSA hepatic studies with biopsies in patients with chronic active hepatitis.

To determine whether scintigraphic findings of Tc-99m DTPA-galactosyl-HSA (GSA) correspond to histopathologic findings, Tc-99m GSA hepatic scintigraphy and biopsy were compared in 65 patients with chronic active hepatitis. After injecting 185 MBq of Tc-99m GSA, anterior images were obtained at 5 minutes and 15 minutes. Scintigrams were classified into three grades according to the extent of visualization of the cardiac blood pool on 5 minute and 15 minute images. Biopsies were subjectively graded for findings of necrosis and fibrosis. Scintigraphic grades on 5 minute images were correlated with hepatic necrosis and fibrosis and those on 15-minute images with hepatic fibrosis. Scintigraphic abnormalities of Tc-99m GSA correlated well with histopathologic abnormalities, especially with hepatic fibrosis and necrosis in patients with chronic active hepatitis.

Adult↗
PubMed1995

Wegener's granulomatosis with relapsed bleeding of gastric ulcers: a case report.

We treated a 55-year-old male patient with Wegener's granulomatosis (WG) associated with frequent gastric bleeding from multiple ulcerative lesions. Only a few cases of frequent hemorrhaging of peptic ulcers associated with WG have been reported. In our case, a gastric biopsy showed mononuclear cell infiltration in the submucosal area, without granulomas or vasculitis. An endoscopic maneuver, as well as administration of immunosuppressive agents, combined with an H2 receptor antagonist and proton pump inhibitor successfully eliminated the gastrointestinal bleeding. In this case, proof that the gastrointestinal involvement was pathologically related to WG could not be demonstrated because neither granulomas nor vasculitis were observed in the insufficient biopsy specimen of the stomach. It is also possible that the uremic state and cytotoxic agents worsened the gastrointestinal involvement. However, immunosuppressive therapy combined with routine antiulcer treatment was very effective in repairing the ulcerative lesions. The gastrointestinal involvement was considered a possible complication of the WG.

Gastroscopy↗
PubMed1993

Quantification of renal uptake of technetium-99m-DTPA using planar scintigraphy: a technique that considers organ volume.

We developed a method to estimate the radioactivity of 99mTc-DTPA within the kidney by planar scintigraphy. Phantom experiments and renal studies were used to compare our method with that of the Gates' method. Our method corrects for scatter and attenuation using the volume depth-independent buildup factor technique, after which background correction is performed with consideration for target organ volume. When the renal phantom-to-background activity concentration ratio (S) was changed from 5 to 80 in a water-filled container and the renal phantom depth was varied from 1 to 11 cm for each value of S, the renal phantom count rate calculated by our method was accurate under all conditions investigated. In contrast, the Gates' method was significantly affected by phantom depth and S values. In 40 patients, renal uptake in the image obtained 2-3 min after injection of 99mTc-DTPA was estimated by our method and the Gates' method, and the correlation between uptake and creatinine clearance was determined. When a ring background region of interest (ROI) around the kidney was employed, a good correlation was obtained by our method (r = 0.947) in comparison with the Gates method (r = 0.887). With both methods, a semilunar background ROI produced poor results than the ring background ROI. In conclusion, renal radioactivity levels that correlate well with creatinine clearance can be obtained by our method, which allows estimation of individual glomerular filtration rates.

Female↗
PubMed1980

A new antibiotic K-82 A and minor components, produced by Streptomyces lavendulae, strain No. K-82.

From the results of taxonomic studies, Streptomyces sp. strain No. K-82 isolated from a soil sample collected in Kumamoto city, was identified as a strain belonging to Streptomyces lavendulae WAKSMAN & HENRICI 1948. The strain produced an active new antibiotic called K-82 A and minor components named the B complex. Antibiotic K-82 A was isolated as dark reddish needles by silica gel column chromatography and found to have both antibacterial activity and high phage induction activity. The K-82 B complex was found to consist of at least five components, among which K-82 B2 and B3 were isolated as crystals. Substances K-82 B2 was identified as benzoic acid from its physicochemical properties. Substance B3 like B2 had only marginal antibiotic activity.

Anti-Bacterial Agents↗
PubMed1979

Successful lymph node transplantation in rats, with restoration of lymphatic function.

After doing a popliteal lymphadenectomy in rats, we were able to transfer a mass of inguinal nodes to the area, either on an island pedicle of the superficial epigastric vessels, or as a free flap by microvascular anastomoses. The transplants survived and at 7 days were able to entrap india ink particles, or particles of radioactive gold, injected in the distal part of the extremity.

Animals↗
PubMed1977

Pallido-nigro-luysial atrophy associated with degeneration of the centrum medianum. A clinicopathologic and electron microscopic study.

A 66-year-old man (case 1) and a 71-year-old woman (case 2) showed systemic degeneration of the globus pallidus, substancia nigra, subthalamic nucleus, centrum medianum thalami and at times, superior colliculus in the midbrain. In the pallido-nigral system, neuronal loss was severe in both cases and an increase of pigment and granular spheroids was marked in case 2, less in case 1. Electron-microscopically, the spheroids consisted of aggregates of highly dense material, often membrane-bound, and varying amounts of groups of loosely packed filaments. Clinical symptoms were stereotyped and unique, showing severe akinesia, no rigidity in the limbs, no tremor but retropulsions, upward gaze palsy, dysarthria, dysphagia and later, nuchal stiffness. Nosological identification is discussed.

Atrophy↗
PubMed1976

[Cystic meningioma--report of two cases (author's transl)].

Cystic changes are rare in meningioma. The authors reported two cases of the cystic meningioma. 1) The first case was 56-year-old female, whose complaints were motor weakness and hypesthesia on the right side. At the operation, a hen egg-sized tumor with a large cyst was removed totally from the left frontoparietal mid-convexity. Multiple cystic cavities were contained in the tumor. Histologically the tumor was compatible with meningocytic meningioma with angiomatous component and showed numerous myxomatous degeneration and swollen vessel-walls. 2) The second case was 17-year-girl complaining of headache, blurred vision, right hemiparesis and episodes of Jacksonian seizure. At the operation, a goose egg-sized tumor in the left parietal lobe was removed and the tumor contained a large cyst. Histologically the tumor was a malignant meningioma, associating with relatively fresh necroses adjacent the cyst. 3) The pathogenesis of the cystic changes in meningioma was discussed.

Adolescent↗