Biomedical subjects

M Nishimura

Publications and source records attributed to M Nishimura.

At least 469 records · Page 26Linked to original sources

PubMed1997

A pumpkin 72-kDa membrane protein of precursor-accumulating vesicles has characteristics of a vacuolar sorting receptor.

Precursor-accumulating (PAC) vesicles were previously shown to mediate the transport of the precursor of a major storage protein (pro2S albumin) to protein-storage vacuoles in developing pumpkin cotyledons. In this study, we characterized two homologous proteins from PAC vesicles, a 72 kDa protein (PV72) and an 82 kDa protein (PV82). PV72 and PV82 showed an ability to bind to peptides derived from both an internal propeptide and a C-terminal peptide of pro2S albumin. PV72 was predicted to be a type I integral membrane protein with epidermal growth factor (EGF)-like motifs. These results suggest that PV72 and PV82 are potential sorting receptors for 2S albumin to protein-storage vacuoles.

2S Albumins, Plant↗

PubMed1997

A rapid increase in the level of binding protein (BiP) is accompanied by synthesis and degradation of storage proteins in pumpkin cotyledons.

The binding protein (BiP) has been implicated in cotranslational folding of nascent polypeptides, and in the recognition and disposal of aberrant polypeptides. To elucidate the involvement of BiP in the biosynthesis of vacuolar proteins, we have characterized the protein in pumpkin cotyledons during seed maturation and seedling growth. Isolated microsomes from maturing pumpkin cotyledons contained a significant amount of BiP, protein-disulfide isomerase and calreticulin. We have purified a 70-kDa protein; sequences of the N-terminus and internal fragments of this protein exhibited a high identity to the sequence of soybean. Immunoblot analysis with specific antibodies raised against the purified BiP showed that the amount of BiP in a cotyledon increased markedly at the middle stages and then decreased. The increase was accompanied by the synthesis of storage proteins and the development of the endoplasmic reticulum in the cotyledons at the middle stage of seed maturation. Most of these storage proteins degraded dramatically between 2 and 5 days after seed germination, and the degradation was also accompanied by a rapid increase in the level of BiP. Subcellular fractionation of the 4-day-old cotyledons showed a high accumulation of BiP in the endoplasmic reticulum. It is possible that BiP might be involved in the synthesis of seed storage proteins during maturation and in the synthesis of hydrolytic enzymes responsible for the degradation of the storage proteins during seed germination.

Amino Acid Sequence↗

PubMed1997

Heterologous expression and subcellular localization of pumpkin seed tonoplast intrinsic proteins (TIP) in yeast cells.

Two tonoplast intrinsic proteins (TIP) of pumpkin seeds, pMP23 and MP28, were expressed in yeast cells under control of the GAL1 promoter, and the subcellular localization of the proteins was analyzed. The pMP23 and MP28 stably accumulated in the yeast vacuolar membrane when the proteins were expressed in the proteinase A-deficient strain (pep4), which lacks the activities of vacuolar proteases. However, pMP23 and MP28 did not accumulate in the wild-type strain; the expressed pMP23 and MP28 were degraded in a proteinase A-dependent manner. These results indicate that pMP23 and MP28 are transported to the vacuolar membrane when expressed in yeast.

Cloning, Molecular↗

PubMed1997

Hydroxypyruvate reductase with a carboxy-terminal targeting signal to microbodies is expressed in Arabidopsis.

Five Arabidopsis EST cDNA clones of hydroxypyruvate reductase (HPR), a photorespiratory enzyme in leaf peroxisomes, were sequenced. Deduced amino acid sequences revealed that HPR in Arabidopsis contained the carboxy-terminal targeting signal to microbodies. Nucleotide sequence analysis showed that the cDNA with the longest insert contained an open reading frame of 1,158 bp which encoded a polypeptide with 386 amino acids with a calculated molecular mass of 42,251 Da. A Southern blot analysis suggested that the Arabidopsis HPR gene, like that of the pumpkin HPR gene, exists as a single copy. Two kinds of pumpkin HPR mRNA might be produced from a single gene by alternative splicing, but the structure of the genomic DNA indicated that the Arabidopsis HPR gene did not undergo alternative splicing. We detected a polypeptide with a molecular mass of 42 kDa in green leaves of Arabidopsis using an HPR-specific antibody. Immunoelectron microscopy revealed that Arabidopsis HPR protein was exclusively localized in leaf peroxisomes in green leaves. These results indicate that HPR is expressed in a form with a carboxy-terminal targeting signal to microbodies and is localized in microbodies in Arabidopsis, suggesting that the differences in the gene structure and the regulation of gene expression of HPR are probably due to species-specific differences in plants.

Alcohol Oxidoreductases↗

PubMed1997

Changes in targeting efficiencies of proteins to plant microbodies caused by amino acid substitutions in the carboxy-terminal tripeptide.

It has been demonstrated that the carboxyl terminus of microbody enzymes functions as a targeting signal to microbodies in higher plants. We have examined an ability of 24 carboxy-terminal amino acid sequences to facilitate the transport of a cytosolic passenger protein, beta-glucuronidase, into microbodies in green cotyledonary cells of transgenic Arabidopsis. Immunoelectron microscopic analysis revealed that carboxy-terminal tripeptide sequences of the form [C/A/S/P]-[K/R]-[I/L/M] function as a microbody-targeting signal, although tripeptides with proline at the first amino acid position and isoleucine at the carboxyl terminus show weak targeting efficiencies. All known microbody enzymes that are synthesized in a form similar in size to the mature molecule, except catalase, contain one of these tripeptide sequences at their carboxyl terminus.

Amino Acids↗

PubMed1997

beta-Glucosidase in the indigo plant: intracellular localization and tissue specific expression in leaves.

beta-Glucosidase of indigo plant (Polygonum tinctorium) has a high substrate specificity for indican (indoxyl beta-D-glucoside). To examine the localization of this beta-glucosidase, we fractionated the cells of the leaves and analysed them immunocytochemically. Immunoelectron micrographs with specific antibodies against the beta-glucosidase clearly showed that the beta-glucosidase was localized in the stroma of the chloroplasts in mesophyll cells, but not in the thylakoid membrane. Chloroplasts were isolated from the crude homogenate of the fresh leaves by Percoll density gradient centrifugation and then subjected to suborganellar fractionation. beta-Glucosidase activity was specifically detected in the stromal fraction, but not in the thylakoid membrane. This was also supported by the result of an immunoblot of the fraction with anti-beta-glucosidase antibodies. The beta-glucosidase was immunocytochemically localized in the chloroplasts of mesophyll cells, but not in any chloroplasts in marginal cells of the vascular bundle or epidermal cells; ribulose 1,5-bisphosphate carboxylase (Rubisco), a typical stromal protein, was observed in all chloroplasts in these cells. These results suggest that beta-glucosidase is tissue specific in its expression in the leaves of the indigo plant.

Plant Leaves↗

PubMed1997

The influence of different types of hard-palate closure in two-stage palatoplasty on maxillary growth: cephalometric analyses and long-term follow-up.

Using cephalometric analysis we investigated the influence on maxillary growth of two different types of hard-palate closure in two-stage palatoplasty. In 12 patients with complete unilateral cleft lip, alveolus, and palate, the lip and soft-palate were closed between 3 and 7 months of age. These 12 patients were then assigned to two groups of 6. In one group the hard palate was closed at 1 year 5 to 11 months of age by a vomer flap with a skin graft (VF group, Osada's two-stage palatoplasty) and in the other group it was closed by the mucoperiosteal pushback procedure (PB group). Sella-nasion-point A (SNA) in the VF group at 3 to 4 and after 10 years of age were within normal range and significantly larger than in the PB group. Two patients in the PB group required orthognatic surgery to obtain normal occlusion and a well-balanced profile. We concluded that in two-stage palatoplasty better maxillary growth can be obtained using the vomer flap method than using the pushback procedure.

Adolescent↗

PubMed1997

Unloadiing of the work of breathing by proportional assist ventilation in a lung model.

OBJECTIVES: Proportional assist ventilation is devised to increase airway pressure in proportion to inspiratory effort. A systematic study of the performance of this new mode of ventilation has not been presented. We tested in the laboratory the capability of proportional assist ventilation to unload the work of breathing in proportion to ventilatory drive, under a variety of mechanical loads. DESIGN: During variations of "ventilatory drive" (i.e., tidal volume), unloading of the work of breathing by proportional assist ventilation was contrasted with unloading by pressure-support ventilation. SETTING: The respiratory laboratory of a university-affiliated teaching hospital. SUBJECT: A bellows-in-a-box lung model, powered by a sine wave air flow generator. INTERVENTIONS: Proportional assist and pressure-support ventilation were preset to provide comparable support at a baseline "ventilatory drive" of 0.7-L tidal volume. The set levels of proportional assist and pressure-support ventilation were subsequently applied to five tidal volumes, from 0.2 to 1.2 L. Three levels of inspiratory support and three settings of mechanical load were evaluated. MEASUREMENTS AND MAIN RESULTS: Proportional assist ventilation significantly (p < .05) reduced the work of breathing of the lung model at all but the lowest tidal volume (0.2 L). The preset proportion of ventilatory support (30%, 50%, and 70%) unloaded the work of breathing uniformly as ventilatory drive was varied at tidal volumes of > or = 0.5 L, but not always at tidal volumes of < or = 0.4 L. In contrast, pressure-support ventilation overassisted low tidal volumes and underassisted high tidal volumes (p < .05). CONCLUSIONS: In a lung model, a prototype system delivering proportional assist ventilation provided uniform unloading of the work of breathing as the ventilatory drive was varied within a tidal volume range of 0.5 to 1.2 L. These findings confirm the theoretical modeling of proportional assist ventilation. This system, however, failed to properly unload low tidal volumes of 0.2 to 0.4 L.

Humans↗

PubMed1997

Sodium intake regulates renin gene expression differently in the hypothalamus and kidney of rats.

OBJECTIVE: To elucidate the different effects of sodium intake on renin messenger RNA (mRNA) in the hypothalamus and the kidney and to investigate the role of hypothalamic renin in sodium-induced hypertension. DESIGN AND METHODS: We investigated the expression of the renin gene in the hypothalamus and the kidney of rats with altered sodium intake and those administered either deoxycorticosterone acetate (DOCA) or sodium. Diets containing a high (8% NaCl), normal (2% NaCl), or low (0.2% NaCl) amount of sodium were administered to 12-week-old male Wistar rats for 10 days or 8 weeks before the rats were killed. Male Wistar rats administered either DOCA or 1% NaCl were killed 2 weeks (during the prehypertensive stage) or 6 weeks (during the hypertensive stage) after the start of treatment. The hypothalamus and kidneys were excised for extraction of total RNA. Competitive polymerase chain reaction of renin mRNA and deletion-mutated renin RNA was performed, and the renin mRNA concentration was calculated. RESULTS: A high sodium intake for 10 days increased the renin mRNA in the hypothalamus; the hypothalamic renin mRNA had not been suppressed after 8 weeks of a high sodium intake despite the lowering in renal renin mRNA. Renin mRNA levels in the hypothalamus were not suppressed either in the prehypertensive or in the hypertensive stage in rats treated with DOCA or sodium, or both, although the renal renin mRNA was reduced in rats administered DOCA or sodium, or both, compared with that in sham-treated control rats, during both stages. CONCLUSIONS: The expression of the renin gene is regulated differently in the rat hypothalamus from that in the kidney. The constant expression of the renin gene in the hypothalamus during a chronic high sodium load might be related at least in part to the mechanism of the activated brain renin-angiotensin system in sodium-induced hypertension.

Animals↗

PubMed1997

Serum hepatocyte growth factor as a possible indicator of arteriosclerosis.

OBJECTIVE: To investigate the possible involvement of hepatocyte growth factor in arteriosclerotic lesions, by studying the relationship between serum concentrations of hepatocyte growth factor and grades of retinal arteriosclerosis. METHODS: We measured the blood pressure, body mass index, serum concentrations of total cholesterol, high-density lipoprotein cholesterol, triglycerides, creatinine, uric acid, total protein, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, gamma-glutamyltranspeptidase, alkaline phosphatase, and hepatocyte growth factor, erythrocyte counts, hemoglobin concentration, and hematocrit levels of 112 adults. Serum concentrations of hepatocyte growth factor were measured by a specific enzyme-linked immunosorbent assay. For each subject, photographs of both optic fundi were taken, and the grade of arteriosclerotic changes in the retinal arteries was evaluated according to Scheie's classification. RESULTS: Individuals with more advanced grades of arteriosclerotic changes had higher serum hepatocyte growth factor values (grade 0, 0.056 +/- 0.004 ng/ml, n = 86; grade 1, 0.132 +/- 0.026 ng/ml, n = 17, P < 0.01, versus grade 0; grade 2-3, 0.271 +/- 0.023 ng/ml, n = 9, P < 0.01, versus grades 0 and 1). The serum hepatocyte growth factor concentrations were also correlated significantly to the serum uric acid concentrations (r = 0.230, P = 0.015) and erythrocyte counts (r = 0.299, P = 0.001), but not to the systolic and diastolic blood pressures, and other physical and humoral parameters. CONCLUSIONS: Serum hepatocyte growth factor levels are thought to indicate the presence or development of arteriosclerotic lesions and may be a useful biochemical parameter for estimating the development of systemic arteriosclerosis irrespective of blood pressure levels.

Adult↗

PubMed1997

Expression of a vacuolar protein (VP24) in anthocyanin-producing cells of sweet potato in suspension culture.

VP24, an abundant protein of 24 kD, was found to accumulate in the anthocyanin-containing vacuoles of cells of sweet potato (Ipomoea batatas) in suspension culture. Light-induced expression of VP24 was analyzed by immunoblotting in three different cell lines that produced anthocyanins at different rates. The expression of VP24 was closely correlated with the accumulation of anthocyanin in these cell lines. Immunocytochemical detection of VP24 with specific antibodies on thin sections showed that VP24 was localized in the intravacuolar pigmented globules (cyanoplasts) in the anthocyanin-containing vacuoles and not in the tonoplast. No VP24 immunogold labeling was detected in the vacuoles of the cell line that does not produce anthocyanin. We suggest that VP24 may be involved in the formation of the cyanoplast via an interaction with anthocyanin, and that it may play an important role in the trapping in vacuoles of large amounts of anthocyanins that have been transported into these vacuoles.

Anthocyanins↗

PubMed1997

Marinesco-Sjögren syndrome associated with acute myeloblastic leukemia.

Marinesco-Sjögren syndrome is a rare autosomal recessive disorder characterized by cerebellar atrophy, ataxia, cataracts, short stature and varying degrees of mental retardation. A high incidence of malignant disease associated with this syndrome has not so far been reported. We report the case of a 6-year-old girl affected with Marinesco-Sjögren syndrome, who developed acute myeloblastic leukemia (AML, M2), and whose karyotype was 46,XX,t(8;21),(q22;q22) in bone marrow blasts. This is the first report of Marinesco-Sjögren syndrome associated with malignant disorders.

Brain↗

PubMed1997

A case of sarcomatoid carcinoma of the thymus.

A 57-year-old woman presented with a 10 x 10 cm anterior mediastinal mass. The tumor had invaded the pericardium, both lungs and the left brachiocephalic vein, and was treated by partial resection and postoperative radiation therapy. Pathological examination of the tumor revealed squamous cell carcinoma with a spindle cell sarcomatous component. Immunohistochemically, keratin and epithelial membrane antigen were positive in both the spindle cell sarcomatous areas and the squamous cell carcinomatous area and thus, a diagnosis of thymic carcinoma of sarcomatoid type was made. The patient died of recurrent disease 1 year after surgery. This case is the seventh reported in the English literature. Because of the poor outcome, adjuvant therapy is recommended.

Carcinoma, Squamous Cell↗

PubMed1997

Recovery of diaphragmatic function in awake sheep after two approaches to thoracic surgery.

Video-assisted thoracoscopic surgery (VATS) is replacing thoracotomy, but no study has addressed the extent or duration of VATS-induced diaphragmatic alteration. We hypothesized that VATS would impair diaphragmatic function less and return diaphragmatic function faster than thoracotomy. In eight sheep, sonomicrometers were randomly implanted on the right costal diaphragm via VATS or thoracotomy. Diaphragmatic resting length, shortening fraction, and respiratory function were measured weekly during quiet breathing (QB) and CO2 rebreathing for 4 wk. For VATS, shortening fraction was smallest on postoperative days 1 (POD 1) (6.4 +/- 3.4 and 12.9 +/- 8.7% during QB and 10% CO2 rebreathing, respectively) and 7 (6.3 +/- 3.4 and 16.9 +/- 4.0% during QB and 10% CO2 rebreathing, respectively) and recovered by 3 wk (13.2 +/- 1.8 and 28.9 +/- 8.0% during QB and 10% CO2 rebreathing, respectively). For thoracotomy, shortening fraction at 10% CO2 rebreathing was smaller on PODs 1, 7, 14 (15.9 +/- 7.1, 13.6 +/- 5.4, and 19.0 +/- 6.9%) than on POD 28 (29.9 +/- 8.2%), but not during QB on POD 1 or 7 (7.5 +/- 3.8 and 3.4 +/- 2.6%) compared with POD 28 (10.7 +/- 8.7%). Shortening fraction did not differ between surgeries. There was no group difference in minute ventilation, respiratory rate, transdiaphragmatic pressure, or esophageal and gastric pressures. In conclusion, although shortening fraction recovered faster for VATS, this translated into insignificant functional differences.

Animals↗

PubMed1997

Continuous versus bilevel positive airway pressure in a patient with idiopathic central sleep apnea.

A 57-yr-old man with idiopathic central apnea is reported. He presented at our hospital complaining of excessive daytime sleepiness. Polysomnography, including esophageal pressure monitoring, confirmed central sleep apnea with an apnea index of 27/h. He had mild non-insulin-dependent diabetes mellitus (NIDDM) but no signs of diabetic neuropathy or other background diseases. The ventilatory responses to hypoxia and hypercapnia tested while he was awake indicated increased respiratory chemosensitivity. We applied nasal continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BPAP) in an attempt to compare the possible difference in therapeutic efficacy. Although nasal CPAP completely reversed central apnea, nasal BPAP adversely affected both apnea length and frequency in an applied pressure-dependent manner. Arterial blood gas analyses while he was being treated indicted alveolar hypoventilation with CPAP and hyperventilation with BPAP. Additionally, administration of a mixed gas containing 5% CO2 through a face mask had a significant effect on the disappearance of central apnea in this patient. These findings support the theory that the arterial PCO2 level is critical in generating idiopathic central apnea and that nasal CPAP therapy may be effective in eliminating central apnea by raising the PaCO2.

Blood Gas Analysis↗

PubMed1997

Mutation analysis and expression of the mottled gene in the macular mouse model of Menkes disease.

The gene for Menkes disease, an X-linked disorder of copper transport, has recently been identified and shown to encode a copper-transporting P-type ATPase. The macular mutant mouse has been proposed as an animal model for Menkes disease. In the present study, we report the finding of a missense mutation in the mottled gene of the macular mouse. A single base change, T to C, at nucleotide position 4223, is predicted to result in an amino acid change from serine to proline at residue 1382 in the eighth transmembrane domain. This mutation differs from the 6-bp deletion we find in brindled cDNA. With validation of macular as an animal model of Menkes disease, we compared mottled gene expression in the intestine, kidney, and brain of macular and normal mice. In Northern analyses an 8.3-kb transcript was detected in the intestine, kidney, and brain of both normal and macular mice, with the level of transcript in macular approximately 80% that of normal. In situ hybridization studies revealed that the mottled gene was clearly expressed in intestinal epithelial cells, Paneth cells, and renal proximal tubular cells of both normal and macular mice. In normal brain, mottled gene expression was most intensely observed in the choroid plexus, in Ammon's born and the dentate gyrus in the hippocampus, in Purkinje cells, and the granular layer of the cerebellum. The intensity and localization of the signals in the brain of macular mice were similar to those of the controls. The distribution of expression of mottled is correlated with cells and tissues showing histopathology or abnormal copper sequestration in macular and other mutants.

Adenosine Triphosphatases↗

PubMed1997

Influence of albumin on enantioselective local disposition of BOF-4272, a xanthine oxidase inhibitor with chiral sulfoxide, in rat liver.

8-(3-Methoxy-4-phenylsulfinylphenyl) pyrazolo[1,5-a]-1,3,5-triazine-4(1H)-one (BOF-4272) blocks xanthine oxidase/xanthine dehydrogenase in the liver. BOF-4272 with a sulfoxide chiral center includes R(+)- and S(-)-enantiomers. The enantioselectivity in the global disposition of BOF-4272 can be attributed to that in the local disposition of organs, especially the liver. Thus, the enantioselectivity in the hepatic local disposition of BOF-4272 was compared between R- and S-enantiomers by a hepatic perfusion experiment with a pulse input into the portal vein. The influence of perfusate albumin on the enantioselective local disposition was also investigated. The elution time profile of each BOF-4272 enantiomer from the liver into the hepatic vein was measured at four different bovine serum albumin (BSA) concentrations (0, 0.25, 1.0 and 4.0%) in the perfusate at 37 and 4 degrees C. A crossover test was carried out for R- and S-enantiomers using one rat liver. In the absence of perfusate BSA at 37 degrees C, hepatic extraction ratios (E[H]) of R- and S-enantiomers of BOF-4272 were 75.6 +/- 4.3% and 71.7 +/- 3.3%, respectively, which were statistically the same. In the presence of 4.0% BSA at 37 degrees C, E(H) values of R- and S-enantiomers were 31.7 +/- 4.6% and 19.6 +/- 3.8%, respectively, which demonstrated that E(H) of R-enantiomer was significantly greater than that of S-enantiomer (p < 0.001). In the absence and presence of perfusate BSA at 4 degrees C, there was no significant difference in E(H) between S- and R-enantiomers. An amplification of stereoselectivity with albumin was observed by the perfusion experiment using BOF-4272 enantiomers.

Albumins↗

PubMed1997

mRNA expression and cDNA sequences of beta- and gamma-sarcoglycans are normal in cardiomyopathic hamster heart.

In BIO14.6 cardiomyopathic hamster heart, the dystrophin-glycoprotein complex is disrupted and sarcoglycans are greatly reduced in abundance. We examined whether the gene expression of beta- and gamma-sarcoglycans is indeed defective in this hamster. We found that mRNA expression for these proteins and the cDNA sequences of their coding regions are identical in both normal and myopathic hamster cardiomyocytes. The results strongly suggest that defect in a currently unknown sarcoglycan-associated protein(s) is responsible for the deficiency of the sarcoglycan complex that leads to muscle cell necrosis in the myopathic hamster.

Amino Acid Sequence↗