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Biomedical subjects

H Murayama

Publications and source records attributed to H Murayama.

At least 55 records · Page 3Linked to original sources
PubMed1998

Distribution of fallover in the carboxylase reaction and fallover-inducible sites among ribulose 1,5-bisphosphate carboxylase/oxygenases of photosynthetic organisms.

The biphasic reaction course, fallover, of carboxylation catalysed by ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) has been known as a characteristic of the enzyme from higher land plants. Fallover consists of hysteresis in the reaction seen during the initial several minutes and a very slow suicide inhibition by inhibitors formed from the substrate ribulose-1,5-bisphosphate (RuBP). This study examined the relationship between occurrence of fallover and non-catalytic RuBP-binding sites, and the putative hysteresis-inducible sites (Lys-21 and Lys-305 of the large subunit in spinach RuBisCO) amongst RuBisCOs of a wide variety of photosynthetic organisms. Fallover could be detected by following the course of the carboxylase reaction at 1 mM RuBP and the non-catalytic binding sites by alleviation of fallover at 5 mM RuBP. RuBisCO from Euglena gracilis showed the same linear reaction course at both RuBP concentrations, indicating an association between an absence of fallover and an absence of the non-catalytic binding sites. This was supported by the results of an equilibrium binding assay for this enzyme with a transition state analogue. Green macroalgae and non-green algae contained the plant-type, fallover enzyme. RuBisCOs from Conjugatae, Closterium ehrenbergii, Gonatozygon monotaenium and Netrium digitus, showed a much smaller decrease in activity at 1 mM RuBP than the spinach enzyme and the reaction courses of these enzymes at 5 mM RuBP were almost linear. RuBisCO of a primitive type Conjugatae, Mesotaenium caldariorum, showed the same linear course at both RuBP concentrations. Sequencing of rbcL of these organisms indicated that Lys-305 was changed into arginine with Lys-21 conserved.

Amino Acid Sequence↗
PubMed1998

Reduced expression of interleukin-11 in bone marrow stromal cells of senescence-accelerated mice (SAMP6): relationship to osteopenia with enhanced adipogenesis.

Aging is associated with an increase in bone marrow adipose tissue and a reduction in bone turnover. The P6 strain of senescence-accelerated mice (SAM) exhibit an early decrease in bone mass with a reduction in bone remodeling. In the bone marrow, suppressed osteoblastogenesis and osteoclastogenesis with enhanced adipogenesis are observed. The present study was undertaken to clarify the mechanism of age-related changes in bone turnover using bone marrow cells from SAMP6 mice. Because interleukin (IL)-11 has been shown to potently inhibit adipogenesis and to stimulate osteoclast formation, the effect of IL-11 on the differentiation of bone marrow cells was examined. The impaired formation of both osteoblasts and osteoclasts was restored and the enhanced formation of adipocytes was suppressed by the addition of 10 pM recombinant human IL-11. Other cytokines that activate gp130 as a common signal transducer, IL-6 and leukemia inhibitory factor, did not have such effects. Sequence analysis of the entire coding region of IL-11 cDNA obtained from SAMP6 stromal cells revealed no mutations. Constitutively secreted IL-11 protein into culture media, and its mRNA expression stimulated by transforming growth factor beta were reduced in stromal cells from SAMP6 compared with those in control mice. These results demonstrate that the expression of IL-11 is reduced in bone marrow cells of SAMP6 and suggest that the reduction in IL-11 actions is involved in the impairment of both osteoblastogenesis and osteoclastogenesis in these mice. There is a possibility that alterations in IL-11 actions may be associated with the age-related impairment in bone metabolism.

Adipose Tissue↗
PubMed1998

A case successfully treated by conservative management for mediastinitis and infected composite graft due to methicillin-resistant coagulase negative staphylococcus.

A 72 year-old man underwent a Bentall procedure for aortic regurgitation secondary to annulo-aortic ectasia and ascending aortic aneurysm. On the 11th postoperative day, the C-reactive protein (CRP) level and white blood cell (WBC) count rose. Echocardiography and a computed tomographic scan showed the appearance of pericardial effusion. A diagnosis of mediastinitis and composite graft infection was made, and mediastinal drainage and irrigation were performed. Methicillin-resistant coagulase negative staphylococcus (MRCNS) was identified as the causative organism. Vancomycin, arbekacin and minocycline were used intravenously. Additionally, a continuous mediastinal irrigation was performed through the chest tubes. CRP level and WBC count were gradually reduced to normal range. He has now been free from signs of infection for more than 3 years. Because MRCNS is considered less virulent than methicillin-resistant Staphylococcus aureus, mediastinitis and composite graft infection due to MRCNS might be treatable by such conservative therapy even in patients with prosthetic implants. Since MRCNS often becomes ubiquitous, preventing infections by strict attention to asepsis is important.

Aged↗
PubMed1997

The local noise property in positron volume imaging and optimal conditions for the signal-to-noise ratio of the 3D reconstructed image.

The local noise property of a 3D PET reconstructed image is investigated for a uniform-activity sphere distributed in a constantly attenuating spherical object. The positional dependence of the statistical noise is approximately derived and calculated for some special cases. It is suggested that a larger diameter of the activity sphere causes noise amplification, and the noise property for the large attenuating sphere is close to that for a non-attenuating object with the same total number of measuring counts. By considering noise propagation of two spherical activity distributions, we suggest that the signal-to-noise ratio of the image depends on a set of projection directions and the sizes and intensities of the activity distributions. In a simple case, we derive an optimal value of the maximum acceptance angle for the projection directions to improve the signal-to-noise ratio of the image.

Humans↗
PubMed1997

Long-term consumption of an amino acid diet reduces the pancreatic enzyme secretion response to a trypsin inhibitor in rats.

We investigated pancreatic enzyme secretion in response to soybean trypsin inhibitor (SBTI) in rats fed amino acids as a nitrogen source, from the fetal stage to adulthood. Pregnant rats were divided into two groups 4 d before parturition. During gestation and nursing, one group was fed a 15% protein diet (protein-fed rats) and the other (amino acid-fed rats) a 15% amino acid mixture diet that simulated the composition of the protein diet. Each male offspring was weaned at 4 wk after parturition and fed the same diet as fed to its dam for an additional 6 wk. Pancreatic amylase secretion in response to an intraduodenal infusion of SBTI (10 mg/rat) was observed in the protein-fed rats but not in the amino acid-fed rats. Amylase secretion in response to an intravenous injection of cholecystokinin (CCK) (10 ng/kg rat) was observed in both groups, and the magnitude of the response was significantly higher in the amino acid-fed rats than in the protein-fed rats. An increase in the level of plasma CCK in response to SBTI was observed in the protein-fed rats but not in the amino acid-fed rats. These results suggest that the long-term amino acid diet, because of its ability to inhibit the SBTI-stimulated CCK-releasing process in the small intestine of rats, reduced the pancreatic enzyme secretion response to a trypsin inhibitor. Six rats fed the amino acid mixture until 1 wk after weaning were fed the protein diet for the next 5 wk. These rats showed no pancreatic amylase secretion in response to SBTI, suggesting that dietary components around the weaning stage may affect the development of the ability of small intestinal cells to recognize a trypsin inhibitor.

Amino Acids↗
PubMed1997

Gastric carcinosarcoma (sarcomatoid carcinoma) with rhabdomyoblastic and osteoblastic differentiation.

A rare case of carcinosarcoma (sarcomatoid carcinoma) with rhabdomyoblastic and osteoblastic differentiation occurring in the gastric remnant is reported. A 69-year-old Japanese man who had undergone a partial gastrectomy for a duodenal ulcer 30 years earlier, presented with anemia, epigastralgia, and an abdominal mass. The diagnosis of gastric carcinosarcoma was made based on the findings of endoscopic biopsies. The patient was thus scheduled to undergo a surgical operation, but he died of respiratory failure. At autopsy, a huge polypoid tumor measuring 20 x 18 x 8 cm was located on the greater curvature of the gastric remnant. Microscopically, the tumor consisted of intimately mixed tubular adenocarcinoma and heterologous mesenchymal elements containing rhabdomyosarcoma and osteosarcoma. Between these components, a morphological transition from the adenocarcinoma element to the sarcomatous element was observed. Ultrastructually, rhabdomyoblastic differentiation was confirmed in the sarcomatous areas. Immunocytochemical expressions of epithelial markers including epithelial membrane antigen and cytokeratins (35bH11 and 34bE12) were recognized not only in the carcinomatous cells but also in the sarcomatous cells. These findings suggest that carcinomatous cells appear to transform into cells with sarcomatous features.

Aged↗
PubMed1997

Analysis of specific accumulation of radiolabeled anti-carcinoembryonic antigen monoclonal antibody CEA 102 in colorectal cancer using computed radiography.

The specific accumulation of radiolabeled anti-carcinoembryonic antigen (CEA) monoclonal antibody (MoAb) CEA 102 in colorectal cancers was investigated by autoradiography of surgical specimens using Fuji Computed Radiography (FCR). Five patients with colorectal cancer were injected intravenously with [13I]-labeled intact CEA 102 or its F(ab')2. Primary tumor and liver metastases were successfully detected by external scanning with gamma camera in four cases. Autoradiographic study using FCR showed predominant localization of [13I]-labeled CEA 102 in primary tumors and liver metastases in all cases. Even the small-sized liver metastasis (0.5 cm) was clearly visualized. The pixel distribution curves showed the heterogeneity of the distribution of administered MoAb in the tumors. In the quantitative distribution analysis of CEA 102, the uptake of the primary tumor was 10-fold greater than that of the normal colon mucosa. These results suggest that MoAb has great potential in radioimmunodetection as well as possible use in antibody-directed therapy.

Antibodies, Monoclonal↗
PubMed1997

[Two operative cases of quadricuspid aortic valve].

We report two cases of rare congenital anomaly of quadricuspid aortic valve. Case 1, an 81-year-old man was operated on because of aortic regurgitation without diagnosis of a quadricuspid aortic valve. He underwent aortic valve replacement with a 21 mm Hancock-II successfully. Case 2, a 40-year-old woman suffering from aortic regurgitation was diagnosed as quadricuspid aortic valve, before surgery using echocardiography and aortography. She underwent aortic valve replacement with a 21 mm H-P St. Jude Medical prosthesis successfully. Both cases were regarded as type c (2 equal larger cusps, 2 equal smaller cusps) by Hurwitz's classification. Thirty cases of quadricuspid aortic valve are reviewed in the Japanese literature including our two cases. All cases underwent aortic valve replacement because of aortic regurgitation. In 19 cases, it was possible to diagnose that those valves were quadricuspid before surgery, using echocardiography and aortography. In conclusion, it is necessary to take quadricuspid aortic valve into consideration in the case of aortic regurgitation.

Adult↗
PubMed1997

[A case report of thoracic aortic aneurysm associated with tubular hypoplasia].

A 55-year-old female was diagnosed as thoracic aortic aneurysm associated with tubular hypoplasia. A saccular aneurysm occupied the aortic arch between left common carotid and left subclavian arteries, arising from the cranial wall of the tubular hypoplasia. The aneurysmectomy was performed under cardiopulmonary bypass with selective cerebral perfusion and woven Dacron graft was implanted. The post-operative course was uneventful and she was discharged 32 days after the operation. Aneurysm associated with coarctation usually is thin walled, therefore an early surgical treatment should be urged.

Aortic Aneurysm, Thoracic↗
PubMed1996

Primary linitis plastica of the rectum: report of four cases and review of the literature.

Primary linitis plastica of the rectum is a rare form of large bowel carcinoma, with only 30 cases having been reported in the English literature to date. Of significance is the fact that it carries a prognosis that is poor compared to other types of colorectal cancers. We report herein the cases of four patients with primary linitis plastica of the rectum who underwent surgery, followed by intensive postoperative chemotherapy using 5-fluorouracil (5-FU) derivatives in our institution. A review of the literature is presented with special reference to the diverse treatment and prognosis of this unusual disease. Although three of the patients died of recurrent cancer, one has survived for 5 years and 10 months despite advanced disease. This is only the third reported case of a patient with linitis plastica of the rectum achieving 5-year survival. We believe that this unexpected long survival could be related to the patient's extensive lymphadenectomy and intensive postoperative chemotherapy using cisplatin and 5-FU derivatives.

Aged↗
PubMed1996

Right-sided ulcerative colitis.

This report describes a case of right-sided ulcerative colitis in which multiple shallow ulcers and erosion with symmetric luminal stenosis were distributed segmentally from the ascending colon to the cecum, with a skip lesion composed of superficial erosions in the right half of the transverse colon. Both the rectum and the left colon were spared at the time of onset. Biopsies taken from the lesions showed non-specific inflammation, while those from the rectum and sigmoid colon showed no abnormal findings. A 5-year follow-up study was made based on radiography and endoscopy. Other inflammatory bowel diseases, such as Crohn's disease, tuberculosis, Yersinosis, Behçet's disease, and ischemic colitis were all ruled out, based on the macroscopic and microscopic findings as well as the clinical course. To our knowledge, this is the first report of right-sided ulcerative colitis that has been followed for a long period.

Adult↗