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Biomedical subjects

A Nakamura

Publications and source records attributed to A Nakamura.

At least 289 records · Page 16Linked to original sources
PubMed1998

Classification of the frog lingual gland cells and their exocytotic features.

We examined under light and electron microscopes the frog lingual gland before and after acetylcholine-stimulation. The lingual gland is composed of five kinds of secretory cells (type 1-5) and ciliated cells. Each secretory cell had numerous cell-type characteristic secretory granules, probably in which both serous and mucous secretory products were contained. The ciliated cells had lysosomes, cytoplasmic filaments and on their apical surface microvilli in addition to cilia. Two kinds of exocytotic features were demonstrated in the secretory cells. One of them, termed multigranular exocytosis, was whole-cell discharge of secretory products in which intracellular huge vacuoles continuous to the cell exterior were formed as the result of multiple granule-to-granule fusion as well as granule-to-plasma membrane fusion. The other type was local exocytotic release of a single or a few secretory granules near the plasma membrane. The multigranular exocytosis was restricted to type 4 and 5 secretory cells while single or a few granular exocytosis was seen in type 1, 2, 4 and 5 secretory cells. This may be because secretory granules are larger and more closely packed in type 4 and 5 secretory cells than in other types of secretory cells. Type 3 secretory cells contained abundant cytoplasmic filaments, and showed no exocytotic feature, suggesting transitional cells between secretory cells and ciliated cells.

Acetylcholine↗
PubMed1998

Synthesis of human erythropoietin in vivo in the oviduct of laying hens by localized in vivo gene transfer using electroporation.

In order to synthesize human erythropoietin protein in the oviduct of laying hens, localized in vivo gene transfer was attempted by using electroporation. In Experiment 1, transcriptional activities were compared by using four viral and cellular promoters, i.e., the 1.35-kbp long ovalbumin promoter, SV40 early promoter, Rous sarcoma virus long terminal repeat (RSV LTR), and the miw promoter, which is a hybrid of RSV LTR and chicken beta-actin promoter. These promoters were fused immediately upstream to the chloramphenicol acetyltransferase reporter gene. The results of chloramphenicol acetyltransferase activity showed that the miw promoter was the strongest, followed by SV40, RSV LTR, and the ovalbumin promoter in decreasing order. The intensity of the miw promoter was 250 times as high as that of the ovalbumin promoter. In Experiment 2, plasmid DNA containing the human erythropoietin gene, driven either by the ovalbumin promoter or the miw promoter, was transfected in vivo, and the production of human erythropoietin protein was detected by ELISA. The results indicated that the synthesis of human erythropoietin protein was attained in the chicken oviduct, and its concentration was higher when driven by the miw promoter than the ovalbumin promoter.

Animals↗
PubMed1998

Molecular basis of the Dark Agouti rat drug oxidation polymorphism: importance of CYP2D1 and CYP2D2.

The Dark Agouti rat has been proposed as a model for the human debrisoquine 4-hydroxylase polymorphism. Earlier studies suggested that the poor metabolizer phenotype in the Dark Agouti rat is caused by the absence of the expression of CYP2D1 mRNA. Although CYP2D1 is the major enzyme catalyzing debrisoquine 4-hydroxylation, other reports have indicated the involvement of a CYP2D, purified from rat hepatic microsomes and presumed to be CYP2D2, which also exhibits this activity. The levels of CYP2D1 and CYP2D2 mRNAs were markedly lower in Dark Agouti as compared to Sprague Dawley rats. Using a baculovirus expression system, recombinant CYP2D1 and CYP2D2 from Spodoptera frugiperda insect cells were examined and were found to both forms catalize debrisoquine 4-hydroxylase activity. These results suggest that reduced debrisoquine 4-hydroxylase activity in the Dark Agouti rat is caused by the low level expression not only of CYP2D1, but also of CYP2D2. Interestingly, bunitrolol 4-hydroxylation was catalyzed by recombinant CYP2D2, while CYP2D1 was inactive toward this substrate. Thus, the low bunitrolol 4-hydroxylation in Dark Agouti rats was caused by the low level of CYP2D2 expression in this rat strain.

Adrenergic beta-Antagonists↗
PubMed1998

Respiratory viral infections in the elderly in a nursing home.

The purpose of this study was to investigate what viruses infiltrate into our nursing home, assess the related clinical symptoms in elderly subjects, and compare the incidence of infections with those in the general community. Between July 1994 and June 1995, 40 elderly persons dwelling in the nursing home were evaluated by clinical observation, serologic analysis, and viral culture of samples to determine the presence of viruses. Enteroviruses and herpes simplex I virus could be isolated from asymptomatic elderly subjects. Individuals with influenza B virus and RSV infections diagnosed by serology did have clinical symptoms. The prevalence of both influenza B virus and enteroviruses was related to that of such viruses in the general community. Our data suggest that respiratory viruses are readily transmitted from the community to nursing home residents.

Aged↗
PubMed1998

Visual function and gene analysis in a family with Oguchi's disease.

A family with 1 case of retinitis pigmentosa (III-1) and 2 cases of Oguchi's disease (III-2, 3) was examined in terms of electrophysiology as well as molecular biology. The proband (III-3), a 42-year-old female, and 2 older brothers (III-1, 2, aged 52 and 45 years) and 2 unaffected members in the same family participated in this study. Corrected visual acuities of the individuals with Oguchi's disease (III-2, 3) were 1.2. On funduscopy, blood vessels stood out in relief against a metallic-appearing background and a Mizuo-Nakamura phenomenon was evident. Full-field electroretinograms (ERGs) recorded from the proband were indicative of rod dystrophy, but results of other electrophysiological examinations (multifocal ERG, pattern ERG and visual-evoked cortical potential recordings) were within normal limits. Patient III-1 had corrected visual acuities of RE 20 cm/m.m. and LE 30 cm/n.d., severe chorioretinal atrophy in both fundi, and full-field ERG revealed rod-cone dystrophy. Mutation of the arrestin gene (1147de1A) was detected in all 3 patients. Visual function in each patient coincides with that of retinitis pigmentosa or Oguchi's disease, respectively.

Adult↗
PubMed1998

vasa is required for GURKEN accumulation in the oocyte, and is involved in oocyte differentiation and germline cyst development.

The Drosophila gene vasa is required for pole plasm assembly and function, and also for completion of oogenesis. To investigate the role of vasa in oocyte development, we generated a new null mutation of vasa, which deletes the entire coding region. Analysis of vasa-null ovaries revealed that the gene is involved in the growth of germline cysts. In vasa-null ovaries, germaria are atrophied, and contain far fewer developing cysts than do wild-type germaria; a phenotype similar to, but less severe than, that of a null nanos allele. The null mutant also revealed roles for vasa in oocyte differentiation, anterior-posterior egg chamber patterning, and dorsal-ventral follicle patterning, in addition to its better-characterized functions in posterior embryonic patterning and pole cell specification. The anterior-posterior and dorsal-ventral patterning phenotypes resemble those observed in gurken mutants. vasa-null oocytes fail to efficiently accumulate many localized RNAs, such as Bicaudal-D, orb, oskar, and nanos, but still accumulate gurken RNA. However, GRK accumulation in the oocyte is severely reduced in the absence of vasa function, suggesting a function for VASA in activating gurken translation in wild-type ovaries.

Animals↗
PubMed1998

[Effects of KB-R7943, a novel Na+/Ca2+ exchange inhibitor, on myocardial ischemia/reperfusion injury].

The effects of KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulfonate) on major ion transporters were studied in canine cardiac sarcolemmal and sarcoplasmic reticular vesicles. KB-R7943 inhibited the Na+/Ca2+ exchange more potently than the Na+/H+ exchange, the Na+/K(+)-ATPase and the Ca2(+)-ATPase. The effects of KB-R7943 on ischemia/reperfusion-induced injury were studied in isolated rat perfused hearts in comparison with those of diltiazem and lidocaine. In normal hearts, diltiazem (10 microM) and lidocaine (100 microM) markedly reduced contractile function, but KB-R7943 (1, 10 microM) had no such effect. In the hearts subjected to 25-min ischemia and 30-min reperfusion, KB-R7943 concentration-dependently and significantly improved post-ischemic recovery of left ventricular developed pressure, left ventricular dP/dtmax and left ventricular end-diastolic pressure by pre-ischemic treatment (5 min) or post-ischemic treatment (10 min). Diltiazem and lidocaine showed similar improvement of recovery by pre-ischemic treatment, but they had no effect by post-ischemic treatment. Furthermore, the effect of KB-R7943 on arrhythmia was studied in anesthetized rats subjected to 5-min cardiac ischmeia and 10-min reperfusion. KB-R7943 (1, 10 mg/kg, i.v.) dose-dependently reduced the incidence and the duration of ventricular fibrillation. These results indicate that KB-R7943, a selective Na+/Ca2+ exchange inhibitor, has beneficial effects against myocardial ischemia/reperfusion injury and suggest that activation of the Na+/Ca2+ exchange mainly occurs immediately after reperfusion in the pathophysiological process of myocardial ischemia/reperfusion injury.

Animals↗
PubMed1998

Isolation of the creA gene from the cellulolytic fungus Humicola grisea and analysis of CreA binding sites upstream from the cellulase genes.

A carbon catabolite repressor gene, creA, was isolated from the cellulolytic fungus Humicola grisea by using a portion of the Trichoderma reesei cre1 gene as a probe. The deduced amino acid sequence predicts a zinc finger protein of 419 amino acids in length, and its zinc finger regions show high similarity with those of Aspergillus CreAs, T. reesei Cre1, and Saccharomyces cerevisiae MIG1. Northern blot analysis showed that the H. grisea creA gene was highly transcribed when the mycelia were grown on glucose-containing media, but the transcription of the H. grisea endoglucanase 1 gene (egl1) and the exoglucanase 1 gene (exo1) were repressed under these conditions. Results of binding assays with the maltose-binding protein::CreA(1-166) fusion protein and the egl1 and the exo1 upstream regions showed that some 6-bp sites having an identical or similar sequence to the consensus sequence for CreA binding were protected from DNase I digestion.

Amino Acid Sequence↗
PubMed1998

Ontogenetic changes in responsiveness to benzodiazepine receptor ligands on ultrasonic vocalizations in rat pups.

The ontogenetic changes in responsiveness to benzodiazepine receptor ligands on ultrasonic vocalizations in rat pups from the age of day 3 to day 12 were evaluated. Rat pups, while separated from their dam and littermates and placed in a cold environment, emit ultrasonic vocalizations. These ultrasonic calls became attenuated dose-dependently in number and power after administration of the anxiolytic diazepam (0.25-1.0 mg/kg, s.c.), but the inhibitory effect of diazepam at the highest dose was less on day 6 and day 9. Moreover, type 1 benzodiazepine receptor ligands, Ro16-6028 and Ro23-0364 (0.5-2.0 mg/kg, s.c.), also dose-dependently attenuated the ultrasonic vocalizations 30-60 min after injection. The inhibitory effects of these drugs became more pronounced with the increasing age of the pup, and they were equivalent on day 12 to those in adult rats. These results suggest that different ontogenetic changes in development of two subtypes of central benzodiazepine receptors of pups might be related in the psychopharmacological mediation of the ultrasonic vocalization.

Animals↗
PubMed1998

A mesenteric liposarcoma with production of granulocyte colony-stimulating factor.

A 77-year-old female was admitted to our hospital because of pyrexia and a right retroperitoneal mass. Leukocytosis and other inflammatory findings were noted. Bone-marrow aspiration revealed hypercellularity with no malignant cells. An additional mass was detected sonographically in the pelvis. The serum concentration of granulocyte colony-stimulating factor (G-CSF) was highly elevated (299 pg/ml). The tumors were removed at laparotomy, and the pelvic mass was found to arise from the ileocecal mesentery. Postoperatively, white blood cell count and serum G-CSF concentrations decreased to normal levels. The mesenteric tumor showed weakly positive immunostaining for human G-CSF, and Northern and polymerase chain reaction (PCR) analyses detected CSF and its mRNA in the mesenteric tumor.

Aged↗
PubMed1998

Effect of vitamin E on contact sensitization responses induced by 2,4-dinitrochlorobenzene in mice.

The effect of vitamin E on the contact sensitization responses induced in mice by 2,4-dinitrochlorobenzene (DNCB) was studied. Mice were fed a vitamin E-adequate or a vitamin E-deficient diet for 5 weeks. The amounts of thiobarbituric acid-reactive substances in the spleens and draining auricular lymph nodes of mice were decreased by dietary vitamin E. Dietary vitamin E prevented lipid peroxidation in the spleens and lymph nodes of mice. Contact sensitization develops in two phases, induction (sensitization) and elicitation. Following sensitization to DNCB on ears, draining lymph node responses, i.e., lymph node weight, total lymph node cell number and in vitro lymph node cell proliferation as assessed by [3H]methyl thymidine incorporation, were examined. These responses, activated by DNCB, were lower in the mice fed a vitamin E-deficient diet as compared with those of the mice fed a vitamin E-adequate diet. In the elicitation phase, lymphocytes from sensitized mice respond to the antigen and blastogenate in vitro. The blastogenesis of spleen lymphocytes in the DNCB-sensitized mice was decreased by vitamin E deficiency, which was enhanced by exogenously adding vitamin E. It was found that vitamin E deficiency decreases the contact sensitization responses to DNCB in mice, but responses were restored by exogenous vitamin E. In conclusion, vitamin E may participate in the lymphocyte responses to contact allergens through scavenging reactive oxygen species.

Animals↗
PubMed1998

In vivo electroporation: a powerful and convenient means of nonviral gene transfer to tissues of living animals (Review).

Although in vivo electroporation is currently an unfamiliar nonviral means of gene transfer, accounting for only about 1% of total studies related to in vivo gene transfer and gene therapy, it may be extensively used for experimental and therapeutic purposes in the near future. Like other nonviral methods, in vivo electroporation has a variety of advantages over viral vectors as: any types of cells and tissues in theory could become a target, handling is easy and quickly done within a matter of second, repeated administration of DNA is possible, no immunogenicity is expected, and there is no constraints on amounts and sizes of DNA to be used. Gene transfer efficiency of in vivo electroporation was found to be equivalent to or even superior to that of in vivo lipofection, gene gun and direct DNA injection methods. Although gene expression exerted is transient and foreign genes are likely to be present in an episomal form when transferred by in vivo electroporation, foreign gene products could be detected for more than 1 month depending on tissues and DNA constructs used. Gene expression generated by in vivo electroporation could be controlled to a certain extent in a tissue- or cell-specific manner, and be induced as intended. Perhaps better appraisal of in vivo electroporation as a nonviral gene transfer method should be brought forth in the future after more detailed analyses.

Animals↗
PubMed1998

[Ocular fundus lesions in systemic lupus erythematosus model mice].

To evaluate spontaneous development of the ocular fundus abnormalities associated with collagen disease, we investigated the ocular fundus lesions in systemic lupus erythematosus (SLE) models. (NZW x BXSB) F1 mice were employed as SLE models with antiphospholipid syndrome. The abnormal findings in the ocular fundus were recorded with a fundus camera for small animals (KOWA Co., Ltd.), and the chorioretinal lesions were studied histopathologically. As in the systemic symptoms of SLE, the incidence of ocular fundus abnormalities in these (NZW x BXSB) F1 mice was significantly higher in males than in females, suggesting the influence of the Yaa (Y chromosome-linked autoimmune acceleration) gene. Lesions in the fundus appeared in the form of white spots, which increased in number along with the course of the disease. The lesion developed into retinal detachment in some animals. Dilatation of veins and narrowing of arteries were marked. These lesions were very similar to multifocal posterior pigment epitheliopathy (MPPE) in humans in that white spots appear first and then develop into exudative retinal detachment caused by retinal pigment epithelial disorder. Histopathological findings included 1. structural destruction of the photoreceptor cell layer, 2. degeneration and loss of the retinal pigment epithelium, and 3. narrowing and occlusion of the choriocapillaris associated with thrombus formation, cellular infiltration into the surrounding tissues, and wall thickening of the choroidal arterioles. The study of these SLE mouse may contribute to the elucidation of abnormalities in the fundus associated with collagen diseases, including the relationship between thrombus formation and antiphospholipid syndrome.

Animals↗
PubMed1998

Paraoxonase has a major role in the hydrolysis of prulifloxacin (NM441), a prodrug of a new antibacterial agent.

NM441 is a prodrug of the new quinolone carboxylic acid antibacterial agent NM394. A rat serum enzyme (NM441-hydrolase) that catalyzes the hydrolysis of NM441 to NM394 was purified by ultracentrifugation, heparin-Sepharose column chromatography, and HPLC with a Mono Q anion exchange column. The enzyme showed a single protein band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its molecular mass was estimated as 46 kDa. The amino-terminal sequence and two internal amino acid sequences of the NM441-hydrolase resemble those of mouse, rabbit, and human serum paraoxonases. Moreover, its enzymatic characteristics (optimum pH, calcium requirement, and molecular mass) were similar to those of the paraoxonases. These findings identify the NM441-hydrolase as rat serum paraoxonase. To determine whether the paraoxonase catalyzes the hydrolysis of NM441 to NM394 in human serum, we investigated whether the paraoxonase and NM441-hydrolase activities were correlated. There was a positive correlation (r = 0.653, p < 0.005) found in the sera of 67 healthy volunteers, indicating that paraoxonase is responsible for the conversion of NM441 to NM394 in humans. Human paraoxonase shows polymorphism. There was a 9-fold variation in paraoxonase activity but only a 2-fold variation in NM441-hydrolase activity. These findings show that paraoxonase polymorphism does not cause marked interindividual variation in NM441-hydrolase activity and is substrate dependent.

Amino Acid Sequence↗
PubMed1998

[A case of Bence-Jones protein-lambda positive multiple myeloma complicated by abnormal plasma cells in pleural effusion].

A 53-year-old woman was admitted to this institution with chest pain and dyspnea. Chest roentgenogram showed pleural effusion and multiple tumor shadows, bilaterally which represented extrapleural signs. Numerous atypical plasma cells were found in the pleural effusion. Bone marrow biopsy showed atypical plasma cells. Immunoelectrophoresis revealed monoclonal Bence-Jones protein-lambda in serum and urine. Myeloma was subsequently diagnosed and chemotherapy was started. Multiple myeloma is a plasmacytoma, and myeloma cells proliferate in the bone marrow. The incidence of myeloma associated with malignant pleural effusion is rare with only 33 cases previously reported in Japan, to the best of our knowledge.

Bence Jones Protein↗
PubMed1998

Evaluation of hair root analysis for acute phencyclidine poisoning and behavior of phencyclidine metabolites in rat hair root.

We evaluated the usefulness of hair root analysis to diagnose acute phencyclidine (PCP) poisoning. Male rats were i.p. administered acute poisonous doses (80, 100 and 120 mg/kg) of PCP hydrochloride and the hair roots were plucked out with hair nippers at certain times after administration. The hair root samples were extracted with methanol/HCl. After evaporation of the solvent, the residue was derivatized with N,O-bis(trimethylsilyl) acetamide and analyzed with GC/MS. PCP was detected at high concentrations (up to 181.7 ng/mg) from all samples. The peak concentrations at every dose were observed at 6 h. The concentrations of PCP in the rat hair roots increased dose-dependently in the range of the doses. 1-(1-Phenylcyclohexyl)-4-hydroxypiperidine (PCHP) and trans-1-phenyl-1(4'-hydroxypiperidino)-4-cyclohexanol (t-PCPdiol) were also detected from 5 and 15 min to 48 h after administration, respectively. It is concluded that hair root is a useful specimen for the diagnosis of acute PCP poisoning because PCP, PCHP and t-PCPdiol are detected very soon after administration and a large amount of them is retained in hair root for a long time. PCHP was found from the early stage in hair roots and its concentration was higher than that of t-PCPdiol for 6 h. However, the concentration of t-PCPdiol became higher than that of PCHP after 6 h. These phenomena could be explained by the time lag of production of the primary (PCHP) and the secondary metabolite (PCPdiol).

Acute Disease↗
PubMed1998

[Resistance to macrolide antibiotics found in methicillin-resistant Japanese clinical isolates of Staphylococcus aureus in 1996].

Minimum inhibitory concentrations (MICs) of erythromycin, clarithromycin, roxithromycin, oleandomycin, triacetyloleandomycin, azithromycin, josamycin and midecamycin were investigated using 200 strains of methicillin-resistant Staphylococcus aureus (MRSA) clinically isolated in Japan during 1996. The results show that the MRSAs could be classified into five groups according to MIC patterns to various macrolides and that more than 88% of the strains used were highly-resistant to all macrolides tested. It was found that 9.0% of the strains examined showed a unique MIC pattern different to that of macrolide-lincosamide-streptogramin B antibiotic resistance type. This group was found to be highly resistant to 14-membered but susceptible to 16-membered macrolides. The resistance induction by erythromycin or oleandomycin was observed to increase for clarithromycin and roxithromycin resistances in a part of strains used. On the other hand, for azithromycin, such induction was not observed.

Anti-Bacterial Agents↗