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Biomedical subjects

A Hirai

Publications and source records attributed to A Hirai.

At least 145 records · Page 8Linked to original sources
PubMed1994

Reversible changes in the composition of the population of mtDNAs during dedifferentiation and regeneration in tobacco.

Differences in the composition of the population of mtDNAs between green plants and calli of tobacco were detected by DNA filter hybridization analysis. The altered composition of the population of mtDNAs observed in calli returned to the composition typical of green plants during the process of regeneration. Quantitative assays revealed that the changes were associated with the differentiation and dedifferentiation of cells since the extent of the change in composition depended on the degree of differentiation of a population of cells. The sequence that accumulated in dedifferentiated cells was shown to be a product of recombination mediated by a 9-nucleotide repeated element, one of which is located at the 5' region of atp6. Although the recombinant sequence was not detected by a hybridization procedure in green plants, its presence was identified by a more sensitive polymerase chain reaction method. The recombination event was shown to result in a deletion that prevents reverse recombination. Therefore, the reversion from the altered composition to the normal state of the population of mtDNAs during regeneration is explained not by recombination but by the preferential amplification of subgenomic mtDNA molecules.

Base Sequence↗
PubMed1994

Nucleotide sequence of a 28-kbp portion of rice mitochondrial DNA: the existence of many sequences that correspond to parts of mitochondrial genes in intergenic regions.

The nucleotide sequence of a 27,588-bp region of rice mitochondrial DNA was determined. This sequence contains putative genes that encode initiator methionine tRNA (trnfM), subunits III (nad3) and IV (nad4) of the NADH dehydrogenase complex, and ribosomal proteins S3 (rps3), S12 (rps12) and L16 (rpl16). An open reading frame that contains sequences homologous to parts of rps2 and atpA is also present. In addition to these regions, there are many short sequences with homology to fragments of mitochondrial DNAs from rice or other plants. These sequences may be remnants of multiple rearrangements of the genome and their presence seems to explain, in part, the large sizes of the mitochondrial genomes of higher plants.

Base Sequence↗
PubMed1994

Eruptive clear cell hamartoma of sweat duct.

A histologically unique condition of the sweat duct was found in a miliaria-like papular eruption on the extensor surfaces of extremities of a 41-year-old female patient. The hypertrophic epithelium of the sweat duct wall consisted of extensively vacuolated clear cells. There was mild hyperkeratosis around the sweat duct orifice. The eccrine gland cells showed only partial vacuolization. Since this condition is not related to any of the other known benign changes of the eccrine duct, we report it with a presumptive descriptive diagnosis of eruptive clear cell hamartoma of sweat duct.

Adult↗
PubMed1994

Regulation of sterol carrier protein 2 (SCP2) gene expression in rat peritoneal macrophages during foam cell formation. A key role for free cholesterol content.

Sterol carrier protein 2 (SCP2) has been shown to be involved in intracellular transport and metabolism of cholesterol. However, there have been no reports concerning SCP2 in macrophages, the major source of atheromatous foam cells. We investigated whether SCP2 is present in rat peritoneal macrophages and determined the changes of SCP2 and its mRNA levels in macrophages during form cell formation induced by acetylated LDL (AcLDL). Immunoblot analysis and Northern blot analysis demonstrated that both SCP2 and its mRNA are expressed in rat peritoneal macrophages. Incubations with AcLDL caused a dose- and time-dependent increase of cellular esterified cholesterol, SCP2 and its mRNA in rat peritoneal macrophages. The inhibitor of acyl-CoA:cholesterol acyltransferase further enhanced AcLDL-induced increase of SCP2 protein and its mRNA. Incubations with 25-hydroxy cholesterol also caused a dose-dependent stimulation of SCP2 gene expression in macrophages, while incubation with maleylated BSA had no effect. These results suggest that the increment of cellular-free cholesterol is responsible for enhanced SCP2 gene expression in macrophages. The enhancement of SCP2 gene expression by AcLDL suggests that SCP2 may play an important role during foam cell formation induced by AcLDL which may be most important step for the atherosclerosis.

Albumins↗
PubMed1994

Detection of DNA strand breaks in barley roots after gamma-ray irradiation using the alkaline unwinding assay.

The alkaline unwinding assay was applied to measure strand breaks in DNA of intact barley roots after gamma-ray irradiation without extracting DNA from the tissue. The most suitable condition for unwinding was determined to be 0.03 M NaOH containing 0.5 M NaCl for alkaline solution composition, and 15 min at 20 degrees C for unwinding time. Under this condition, DNA strand breaks were shown to be linearly increased with increasing dose, and further be rejoined during the post-irradiation incubation for 6 hr.

DNA↗
PubMed1994

Urinary chiro-inositol excretion is an index marker of insulin sensitivity in Japanese type II diabetes.

OBJECTIVE: To determine the relationship between urinary chiro-inositol excretion and insulin sensitivity in Japanese type II diabetic patients. RESEARCH DESIGN AND METHODS: Eighteen subjects were age-matched, nonobese, type II diabetic patients. Eight subjects had impaired glucose tolerance (IGT), and 10 had normal glucose tolerance (NGT). We quantified urinary chiro-inositol excretion using gas chromatography-mass spectrometry and the insulin sensitivity index (SI), and glucose effectiveness (SG) using Bergman's modified minimal model method. RESULTS: The urinary excretion of chiro-inositol was much lower in the diabetic patients (32.3 +/- 16.0 mumol/day, means +/- SD) than in the NGT subjects (96.0 +/- 17.6; P < 0.0001) and IGT subjects (58.9 +/- 11.6; P < 0.0001). SI was much lower in the diabetic patients (3.81 +/- 1.49) than in the NGT subjects 6.30 +/- 1.59, P < 0.0005). SG was much lower in the diabetic patients (2.14 +/- 0.56) than in the NGT subjects (3.07 +/- 0.38, P < 0.0001). There was a significant correlation between urinary chiro-inositol excretion and SI (r = 0.766), as well as a significant correlation between urinary chiro-inositol excretion and SG (r = 0.747).

Diabetes Mellitus, Type 2↗
PubMed1993

Effect of the infusion of OKY-046, a thromboxane A2 synthase inhibitor, on urinary metabolites of prostacyclin and thromboxane A2 in healthy human subjects.

The influence of OKY-046, a selective thromboxane synthase inhibitor, on prostanoid formation in healthy human subjects was studied. Vehicle (5% glucose solution) or OKY-046 in 5% glucose solution at 15 micrograms kg-1 min-1 was intravenously administered to five male healthy volunteers for 6 h. Platelet aggregation and thromboxane B2 (TXB2) formation induced by collagen and arachidonic acid were suppressed by the infusion of OKY-046, while both were not affected by the infusion of vehicle. Urinary excretion of 11-dehydro-thromboxane B2, one of major urinary metabolites of thromboxane A2 (TXA2) was decreased by the infusion of OKY-046, while that of 2,3-dinor-6-keto-prostaglandin F1 alpha, one of major urinary metabolites of prostacyclin (PGI2) was increased. The present study demonstrated that the infusion of OKY-046 improved the balance of TXA2/PGI2 into antithrombotic state in healthy subjects. It was also suggested that endogenously produced (probably platelet-derived) endoperoxides could be redirected into prostacyclin in vivo.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Identification of the entire set of transferred chloroplast DNA sequences in the mitochondrial genome of rice.

The entire set of transferred chloroplast DNA sequences in the mitochondrial genome of rice (Oryza sativa cv. Nipponbare) was identified using clone banks that cover the chloroplast and mitochondrial genomes. The mitochondrial fragments that were homologous to chloroplast DNA were mapped and sequenced. The nucleotide sequences around the termini of integrated chloroplast sequences in the rice mtDNA revealed no common sequences or structures that might enhance the transfer of DNA. Sixteen chloroplast sequences, ranging from 32 bases to 6.8 kb in length, were found to be dispersed throughout the rice mitochondrial genome. The total length of these sequences is equal to approximately 6% (22 kb) of the rice mitochondrial genome and to 19% of the chloroplast genome. The transfer of segments of chloroplast DNA seems to have occurred at different times, both before and after the divergence of rice and maize. The mitochondrial genome appears to have been rearranged after the transfer of chloroplast sequences as a result of recombination at these sequences. The rice mitochondrial DNA contains nine intact tRNA genes and three tRNA pseudogenes derived from the chloroplast genome.

Base Sequence↗
PubMed1993

A transcription map of the chloroplast genome from rice (Oryza sativa).

The complete nucleotide sequence (134,525 bp) of the chloroplast genome from rice (Oryza sativa L.) contains four rRNA genes, 30 tRNA genes, and over 100 genes that encode proteins. However, expression of only a few of these genes, namely psbA, rbcL, and atpB/E, has been detected. We constructed the complete transcription map of rice chloroplast DNA by Northern hybridization of total RNA from rice seedlings, using subclones from a clone bank of rice chloroplast DNA as probes. Approximately 90% of the chloroplast genome was transcribed, as detected by a non-radioactive hybridization system. Most of the genes on the chloroplast DNA are organized as clusters and are co-transcribed as long primary transcripts. We identified 16 polycistronic transcripts from the rice chloroplast genome. Furthermore, the genes for components of photosystems I and II, the gene for the large subunit of RuBisCO, the genes for ATPase, the genes for components of the cytochrome complex, and the rRNA genes were expressed at the highest levels.

ATP Synthetase Complexes↗
PubMed1993

Bombesin stimulates intracellular Ca2+ mobilization but not proliferation on human colon cancer cells.

Increases in intracellular Ca2+ ([Ca2+]i) levels mediated by bombesin (BBS) are believed to be important signals leading to stimulation of DNA synthesis and an increase in cellular proliferative rate. Since the role of BBS on growth of normal or malignant cells in the GI tract is still unclear, we examined whether BBS affects in vitro growth of human colon cancer cells (COLO 320, HCT116 and LoVo). We also examined the effect of BBS on intracellular Ca2+ levels to determine if the growth-regulatory effect of BBS is mediated through increases in [Ca2+]i. Levels of [Ca2+]i in response to BBS were measured by single cell fluorescence after loading with fura-2. BBS stimulated the mobilization of [Ca2+]i in COLO 320, LoVo, and HCT116 cells in a dose-dependent fashion, but did not affect in vitro growth. These findings suggest that the BBS-mediated increase in [Ca2+]i does not always correlate with the growth-regulatory effect of BBS.

Bombesin↗
PubMed1993

Carcinosarcoma of the skin: immunohistochemical and electron microscopic observations.

A rapidly growing, hemorrhagic, exophytic tumor on the upper back of a 44-year-old male patient was investigated. Histological, immunohistochemical, and electron microscopic studies revealed both basal cell carcinoma-like and spindle cell sarcoma-like structures intermingled in the same tumor. Clinical consequences to this patient were mainly dependent on the sarcomatous element.

Adult↗
PubMed1993

Malignant exophthalmos associated with multiple myeloma.

We report a patient with malignant exophthalmos associated with multiple myeloma which showed no evidence of direct orbital involvement of plasma cells. This exophthalmos had similarities with Graves' ophthalmopathy, but the patient had no detectable autoimmune thyroid diseases. Plasmapheresis was effective not only for the treatment of heart and renal failure due to the myeloma kidney but also for the malignant exophthalmos. As the serum monoclonal IgG level was decreased by plasmapheresis, the improvement of proptosis, visual acuity, and hypertrophy of the extraocular muscle as measured by magnetic resonance imaging were observed. It is suggested that humoral factors removed by plasmapheresis might be involved in the pathogenesis of this nonendocrine exophthalmos.

Aged↗
PubMed1992

Epoxyeicosatrienoic acid stimulates ADP-ribosylation of a 52 kDa protein in rat liver cytosol.

In rat liver cytosol, rapid ADP-ribosylation of a 52 kDa protein by endogenous ADP-ribosyltransferase(s) was observed. This ADP-ribosylation was stimulated dose-dependently by 14,15-epoxyeicosatrienoic acid (14,15-EET), one of the metabolites of arachidonic acid by NADPH-dependent cytochrome P-450 mono-oxygenase. This stimulatory effect required the presence of GTP or its non-hydrolysable analogues, guanosine 5'-[beta gamma-imido]triphosphate or guanosine 5'-[gamma-thio]triphosphate. Of four regioisomeric EETs, 14,15-EET was the most potent. No stimulatory effect was observed with addition of 14,15-dihydroxyeicosatrienoic acid, a stable metabolite of 14,15-EET. The 52 kDa protein was not ADP-ribosylated by cholera toxin A subunit and pertussis toxin, and was not recognized by anti-Gs alpha and anti-Gi alpha antibodies. However, the 52 kDa protein could be photoaffinity-labelled with 8-azidoguanosine 5'-[alpha-32P]triphosphate. These results suggest that the 52 kDa protein is neither Gs nor Gi, though it may have a GTP-binding site. These results contribute to the understanding of the role of mono-oxygenase metabolites of arachidonic acid in intracellular signal transduction.

8,11,14-Eicosatrienoic Acid↗
PubMed1992

[Vasopressin (ADH)].

Vasopressin is thought to play an important role, not only in the metabolism of water and electrolytes, but also in the regulation of renal hemodynamics. This year, great progress has been achieved in molecular biology of vasopressin receptors. First, the cloning of a complementary DNA, encoding the rat liver V1a arginine vasopressin receptor, was reported. The liver cDNA encodes a protein with seven putative transmembrane domains, which binds arginine vasopressin and related compounds with affinities similar to the native rat V1a receptor. The messenger RNA, corresponding to the cDNA, is distributed in rat tissues, known to contain V1a receptors. Second, the cloning of a complementary DNA encoding the rat kidney V2 arginine vasopressin receptor was also successful. The kidney cDNA encodes a protein with a transmembrane topography characteristic of G protein-coupled receptors. The receptor messenger RNA is detected only in the kidney. Last year, an orally active and specific vasopressin V1 receptor antagonist, OPC-21268 was first reported. The i.v. or p.o. administration of OPC-21268 dose-dependently inhibited vasopressin-induced vasoconstriction, while that induced by angiotensin II was not affected. OPC-21268 may have clinical potentials in certain hypertensive cardiovascular disorders. In addition, an orally active and specific vasopressin V2 receptor antagonist, OPC-31260 was also reported. Oral administration of OPC-31260 inhibited antidiuretic action of arginine vasopressin. OPC-31260 is thought to be useful in the treatment of certain disorders, such as the syndrome of inappropriate secretion of ADH (SIADH).

Amino Acid Sequence↗