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Biomedical subjects

M Arita

Publications and source records attributed to M Arita.

At least 145 records · Page 8Linked to original sources
PubMed1996

Pheochromocytoma-related myocardial damage following delivery.

We present the case of a 35-year-old woman whose pregnancy was complicated by the rare condition of transient pheochromocytoma-related myocardial damage. Short-duration left ventricular dysfunction was apparently caused by acute non-transmural myocardial infarction provoked by coronary artery vasospasm rather than catecholamine-induced cardiomyopathy. Forty-eight days after onset, a 50 x 55 x 35 mm tumor was excised and histologically confirmed to be a pheochromocytoma.

Adult↗
PubMed1996

Age-related changes of alpha-tocopherol transfer protein expression in rat liver.

Developmental changes in expression of alpha-tocopherol transfer protein (alpha-TTP) after birth were investigated using rats with respect to plasma changes of tocopherols. The expression of alpha-TTP in the neonatal rat liver, which was very low immediately after birth, increased steadily during the two weeks of life before weanling and reached the adult level at four weeks. During the suckling period, the plasma ratio of alpha-tocopherol to gamma-tocopherol linearly increased, because plasma alpha-tocopherol which was low immediately after birth, increased rapidly during the period, while gamma-tocopherol remained unchanged. The increase in the ratio seemed to correlate with the developmental expression of alpha-TTP in the liver during this period. The ratio also reached the adult level after four weeks. The expression of alpha-TTP was investigated using primary cultured rat hepatocytes. The expression of alpha-TTP was found to be extremely low after 20h of culture. The decrease in alpha-TTP expression was exacerbated by adding epidermal growth factor to the culture medium and was inhibited by adding dexamethasone. These observations suggest that expression of alpha-TTP may be affected by the state of hepatic differentiation.

Aging↗
PubMed1996

[Change in argatroban concentration within the vessel wall after local administration using hydrogel-coated balloon catheter].

Acute coronary occlusion after percutaneous transluminal coronary angioplasty is one of the major problems in coronary intervention. This study evaluated the hydrogel-coated balloon delivery of argatroban to the arterial wall and argatroban persistence after angioplasty in 17 rabbits. A hydrogel-coated balloon was immersed three times in argatroban/saline solution (1 mg/ml) and inflated at 6 atm pressure for 1 min in the common carotid artery. The transfer of argatroban to the vascular wall was measured by high-performance liquid chromatography. The concentrations of argatroban at 0, 5, and 15 min after deflation were 14.8, 4.2, and 3.9 nmole/g.wet weight. The hydrogel-coated balloon catheter can deliver argatroban to the local arterial wall during balloon inflation.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Diffuse alveolar hemorrhage after allogeneic bone marrow transplantation].

A 44-year-old woman with malignant T-cell lymphoma and secondary leukemia received an allogeneic bone marrow transplant (BMT). She had received BMT conditioning treatment with total body irradiation and chemotherapy. Hemoptysis and progressive dyspnea developed 11 days after the transplant. A chest roentgenogram showed bilateral diffuse infiltrates. Bronchoalveolar lavage fluid was bloody, and diffuse alveolar hemorrhage (DAH) was diagnosed. Respiratory failure progressed despite mechanical ventilation and administration of corticosteroids. The patient died 58 days after the transplant DAH after BMT has been recognized in western countries as a syndrome with high mortality. We draw attention to the fact that DAH is a serious early pulmonary complication of BMT also in Japan.

Adult↗
PubMed1996

[Prospective study of the etiology of community-acquired pneumonia among patients in a general hospital].

We prospectively studied the etiology of community-acquired pneumonia among all patients who were admitted to our hospital from July 1994 to June 1995. Tests for microbial pathogens including Chlamydia spp. and Legionella spp. were performed and diagnoses were made with strict criteria. A total 110 patients with 111 episodes of pneumonia were evaluated, and a pathogen was identified in 61 episodes (55%). The most common pathogen was Streptococcus pneumoniae (18%), followed by Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Mycoplasma pneumoniae, and Chlamydia spp. Infection with Legionella pneumophila was not found. Dual pathogens were identified in five episodes. Few prospective studies of the etiology of community-acquired pneumonia have been done in Japan. To prepare guidelines for the management of community-acquired pneumonia in Japan, a national study of the etiology of pneumonia is necessary.

Adult↗
PubMed1996

[Heart conduction system and accessory pathways].

The morphology of atrioventricular (AV) junctions in the heart has been investigated using comparative anatomical analyses. For scanning electron microscopy, tissue blocks are treated with HCl to digest connective tissue elements. In fishes, amphibians and reptiles, there is a muscular system connecting the atrial muscle to the ventricular myocardium. These muscle fibers completely surround the inner surface of the atrioventricular ring and termed "ring muscular tissue", the cells of which are slender and small and vertically oriented. They contain small-sized mitochondria, relatively few myofibrils and variable amounts of glycogen. In mammalian hearts, the AV node and bundle system is the only functional myocardial connection between the atria and ventricles. Architecture and ultrastructure of AV nodal cells are similar to those of AV ring muscular tissue seen in the lower vertebrates. In human hearts, however, the muscle bundles which directly connect the atrium with the ventricle, i.e., accessory conduction pathways, are scarcely encountered. From the developmental- and comparative-anatomical points of view, it is likely that the accessory pathways in man are the remnants of the ring muscular tissue seen in lower vertebrates.

Animals↗
PubMed1996

[IgM antibody against sulfated glucuronyl paragloboside in a case of Guillain-Barré syndrome].

High-titer IgM antibody against sulfated glucuronyl paragloboside (SGPG) was detected in a case of Guillain-Barré syndrome. The patient recovered rapidly by the treatment with double filtration plasmapheresis and the anti-SGPG antibody was not detected on the 40th day of illness. Facial nerve palsy, however, lasted until the 6th month of illness. Anti-SGPG antibody might have the important role in the pathologic mechanisms of Guillain-Barré syndrome in this case.

Adult↗
PubMed1996

[Dietary pattern and nutrient intake in preschool children from three rural villages in the Province of Santa Rosa, Guatemala].

We present here the results of a nutritional survey to show the pattern of food consumption, as well as nutrient intake, of 303 pre-school children (six to 71 months old) from three rural hamlets of the South-East region of Guatemala. This survey was performed prior to the establishment of a nutritional intervention in the same geographical area. Information was gathered from June through August 1991, by personnel from the Center for Studies of Sensory Impairment, Aging, and Metabolism (CeSSIAM) using two data collection instruments during home visits. Informats were mothers or other caretakers in charge of the children feeding. Data collected were initially converted to individual food item weight, and then, to micronutrients values. These values were used to establish their adequacy to standard requirements for children of these ages. Results showed a pattern in which corn tortilla, and beans were the most commonly consumed food items. Those items were also the relatively most important sources of calories, protein, and iron. Vitamin A intake was low, and it came mainly from plant sources. Nutrients intake was below the recommended dietary allowances, except for protein and iron.

Calcium, Dietary↗
PubMed1995

Adult-onset spinocerebellar dysfunction caused by a mutation in the gene for the alpha-tocopherol-transfer protein.

BACKGROUND: Patients with isolated vitamin E deficiency have an impaired ability to incorporate alpha-tocopherol into lipoproteins in the liver and usually have symptoms and signs of spinocerebellar dysfunction before adolescence. Accumulated evidence suggests that the alpha-tocopherol-transfer protein, which is presumed to function in the intracellular transport of alpha-tocopherol, is abnormal in these patients. METHODS: We studied a patient from an isolated Japanese island who began to have ataxia, dysarthria, and sensory disturbances in the sixth decade of life. His serum vitamin E concentration was low (1.2 micrograms per milliliter [2.8 mumol per liter]). Exons of his gene for the alpha-tocopherol-transfer protein were analyzed by DNA sequencing. We also screened an additional 801 inhabitants of the island for the mutation. Both the normal and mutant alpha-to-copherol-transfer proteins were expressed in COS-7 cells and studied by immunoblot analysis and assay for alpha-tocopherol-transfer activity. RESULTS: The patient was homozygous for a point mutation that replaces histidine (CAT) with glutamine (CAG) at position 101 of the gene for the alpha-tocopherol-transfer protein. When expressed in COS-7 cells, the missense mutation produced a functionally defective alpha-tocopherol-transfer protein with approximately 11 percent of the transfer activity of the wild-type protein. Of the 801 island inhabitants examined, 21 were heterozygous for the His101Gln mutation. In all affected subjects, including the patient, this mutation cosegregated with an intron-sequence polymorphism. The heterozygotes were phenotypically normal and had serum vitamin E concentrations that were on average 25 percent lower than those of normal subjects (mean [+/- SD], 7.5 +/- 2.2 vs. 10.1 +/- 2.8 micrograms per milliliter [17.4 +/- 5.1 vs. 23.4 +/- 6.5 mumol per liter]; P = 0.002). CONCLUSIONS: alpha-Tocopherol-transfer protein is a determinant of serum vitamin E concentrations. An abnormality in this protein is a cause of spinocerebellar dysfunction.

Adult↗
PubMed1995

Transgenic mice with targeted inactivation of the Col2 alpha 1 gene for collagen II develop a skeleton with membranous and periosteal bone but no endochondral bone.

Homologous recombination in embryonic stem cells was used to prepare transgenic mice with an inactivated Col2a1 gene for collagen II, the major protein component of the extracellular matrix of cartilage. Heterozygous mice had a minimal phenotype. Homozygous mice developed into fetuses that were delivered vaginally but died either just before or shortly after birth. The cartilage in the mice consisted of highly disorganized chondrocytes with a complete lack of extracellular fibrils discernible by electron microscopy. There was no endochondrial bone or epiphyseal growth plate in long bones. However, many skeletal structures such as the cranium and ribs were normally developed and mineralized. The results demonstrate that a well-organized cartilage matrix is required as a primary tissue for development of some components of the vertebrate skeleton, but it is not essential for others.

Animals↗
PubMed1995

University of Wisconsin solution preserves myocardial calcium current response to isoproterenol in isolated canine ventricular myocytes.

BACKGROUND: University of Wisconsin (UW) solution has been shown to be an effective solution for cold storage of various organs. This study was designed to evaluate the subcellular protective mechanism of UW solution during cardiac myocyte storage using patch-clamp techniques for the first time as a tool for the detection of myocyte viability. METHODS AND RESULTS: The protective effects of UW solution on the preservation of dihydropyridine-sensitive Ca2+ channel current response to catecholamine were evaluated in canine cardiac ventricular cells by measurement of single channel open probability. Single ventricular myocytes were isolated and stored in UW solution, in Stanford (SF) solution, or in St Thomas' (ST) solution at 4 degrees C for 2, 6, 12, and 24 hours, and after each storage period, recordings were made of cell-attached single Ca2+ channel currents. When 0.1 mumol/L isoproterenol was applied, percent mean open probability of the Ca2+ channel tested in freshly isolated cells was 167 +/- 4% (n = 24) of controls (100%). The response was decrescent with increased duration of the hypothermic storage and was only 130 +/- 12% (n = 4) after 24 hours of storage in SF solution and 135 +/- 9% (n = 7) in ST solution. However, it was significantly highly preserved as much as 165 +/- 9% (n = 6) in UW solution. Ca2+ channel kinetics and channel conductance were not changed after up to 24 hours of hypothermic storage. CONCLUSIONS: Hypothermic storage of canine cardiac myocytes in UW solution preserved beta-adrenergic response, which suggests that UW solution during cold storage preserved high-energy phosphates in myocytes that are responsible for Ca2+ channel phosphorylations.

Adenosine↗
PubMed1995

Pharmacological evidence for the persistent activation of ATP-sensitive K+ channels in early phase of reperfusion and its protective role against myocardial stunning.

BACKGROUND: The activation of cardiac ATP-sensitive potassium channels is reported to protect myocardium during ischemia. However, the behavior and role of this channel during reperfusion remain uncertain. METHODS AND RESULTS: Guinea pig right ventricular walls were studied by use of microelectrodes and a force transducer. Each preparation was perfused via the coronary artery at a constant flow rate and was stimulated at 3 Hz. In the first protocol, the preparation was subjected to 10 minutes of no-flow ischemia, which was followed by 60 minutes of reperfusion. Introduction of ischemia shortened the action potential duration (APD) to 58.7 +/- 3.1% of the preischemic values, in association with a decrease in the resting membrane potential (by 12 +/- 0.8 mV) and action potential amplitude (by 34.6 +/- 1.8 mV). On reperfusion, although the APD was restored, it remained shortened for up to approximately 30 minutes of reperfusion. In the presence of glibenclamide (10 mumol/L), the shortening of the APD during ischemia was significantly attenuated and the restoration of APD after reperfusion was significantly facilitated. When glibenclamide was applied from the onset of reperfusion, the persistent APD shortening was significantly suppressed. The developed tension decreased during ischemia and recovered after 60 minutes of reperfusion (up to 92.0 +/- 6.4% of preischemic values) in the untreated preparations. The application of glibenclamide that was started before ischemia or from the onset of reperfusion significantly suppressed the recovery of contractility (P < .05 versus untreated preparations). In the second series of experiments, 20 minutes of no-flow ischemia and 60 minutes of reperfusion were applied. This protocol produced a sustained contractile dysfunction after reperfusion (to 34.0 +/- 3.2% of preischemic values). In the presence of cromakalim (2 mumol/L), the APD shortening was enhanced during both ischemia and the early reperfusion period. Cromakalim significantly improved the contractile recovery (to 79.3 +/- 4.1% of preischemic values, P < .05 versus untreated preparations). The application of cromakalim that was started from the onset of reperfusion also improved the contractile recovery during this phase and this effect was associated with enhanced APD shortening. However, the cromakalim-treated preparations demonstrated a higher incidence of ventricular fibrillation during reperfusion. CONCLUSIONS: Cardiac ATP-sensitive potassium channels are activated by ischemia, and a fraction of these channels remains activated during the early reperfusion phase. The resulting shortening of the APD prevents the heart from developing myocardial stunning.

Action Potentials↗
PubMed1995

Sandwich immunoassay specific for the N-terminal sequence of osteocalcin.

A monoclonal antibody (10B) against the N-terminal sequence of human osteocalcin was selected to characterize its epitope and species specificity. The cross-reactivity of 10B with human and rat osteocalcin demonstrated that the reactivities of 10B with both human and rat osteocalcins were very similar. The pin technology method was used to determine the epitope and clearly demonstrated that the epitope recognized by 10B was localized to residues 12-16, the sequence of which is identical in rat and human osteocalcin molecules. This monoclonal antibody was found to be useful for designing region-specific sandwich immunoassay systems for human and rat N-terminal osteocalcin (N-OC) molecules using rabbit anti-hN20 and anti-rN20 polyclonal antibodies, respectively. The osteocalcin levels in serum determined by this N-OC method were stable during prolonged storage at 25 degrees C and the method could be usefully applied in the development of immunoassay systems for many osteocalcin molecules from many other species.

Amino Acid Sequence↗
PubMed1995

Tissue-specific expression of the gene for type I procollagen (COL1A1) in transgenic mice. Only 476 base pairs of the promoter are required if collagen genes are used as reporters.

Inconsistent data have been reported on the size of the promoter that is necessary for high levels of tissue-specific expression of the COL1A1 gene for type I procollagen. Some of the inconsistencies may be traced to the use of reporter gene constructs. Therefore, we prepared transgenic mice with modifications of the intact gene engineered so that the level of expression of the transgene could be assayed both as mRNA and protein that were similar to the products from the endogenous COL1A1 gene. The results with a mini-COL1A1 gene lacking 41 internal exons and introns indicated that the first intron and 90% of the 3'-untranslated region were not essential for tissue-specific expression. In a hybrid COL1A1/COL2A1 construct, a 1.9-kilobase 5'-fragment from the COL1A1 gene that contained only 476 of the promoter was linked to a promoterless 29.5-kilobase fragment of the human COL2A1 gene for type II procollagen. The hybrid COL1A1/COL2A1 construct was expressed as both mRNA and protein in tissues that normally synthesize type I procollagen but not type II procollagen. Apparently, 476 base pairs of the promoter are sufficient to drive tissue-specific expression of the COL1A1 gene and totally inappropriate expression of the COL2A1 gene.

Animals↗
PubMed1995

Human alpha-tocopherol transfer protein: cDNA cloning, expression and chromosomal localization.

alpha-Tocopherol transfer protein (alpha TTP), which specifically binds this vitamin and enhances its transfer between separate membranes, was previously isolated from rat liver cytosol. In the current study we demonstrated the presence of alpha TTP in human liver by isolating its cDNA from a human liver cDNA library. The cDNA for human alpha TTP predicts 278 amino acids with a calculated molecular mass of 31,749, and the sequence exhibits 94% similarity with rat alpha TTP at the amino acid level. The recombinant human alpha TTP expressed in Escherichia coli exhibits both alpha-tocopherol transfer activity in an in vitro assay and cross-reactivity to the anti-(rat alpha TTP) monoclonal antibody. Northern blot analysis revealed that human alpha TTP is expressed in the liver like rat alpha TTP. The human and rat alpha TTPs show structural similarity with other apparently unrelated lipid-binding/transfer proteins, i.e. retinaldehyde-binding protein present in retina, and yeast SEC14 protein, which possesses phosphatidylinositol/phosphatidylcholine transfer activity. Both Southern-blot hybridization of human-hamster somatic cell hybrid lines and fluorescence in situ hybridization revealed a single alpha TTP gene corresponding to the 8q13.1-13.3 region of chromosome 8, which is identical to the locus of a recently described clinical disorder, ataxia with selective vitamin E deficiency (AVED). The relationship between alpha TTP and AVED will be discussed.

Amino Acid Sequence↗
PubMed1995

Characterization of measles viruses isolated after measles vaccination.

Seven measles virus (MV) strains were isolated from children who developed clinical signs of fever and rash 3-9 days after measles vaccination. The nucleotide sequence of the H gene, the molecular size of the H protein, the haemadsorption activity on African green monkey red blood cells, and antigenicity as determined by virus neutralization revealed that one strain was of the vaccine type and the remaining six were the wild virus type. Isolation of the virus directly from patients suspected of a vaccine-induced side-reaction and subsequent characterization of such isolated virus may be useful in differentiation between vaccine-induced side-reactions and natural measles.

Antibodies, Monoclonal↗
PubMed1995

Central nervous system disease in a child with primary Sjögren syndrome.

A 9-year-old girl had hemiparesis, and a diagnosis of primary Sjögren syndrome was made. The neurologic dysfunction was multifocal, involving both the brain and spinal cord, and was recurrent; the findings mimicked multiple sclerosis. Corticosteroid treatment during episodes of acute neurologic dysfunction appeared to be beneficial.

Brain↗