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Biomedical subjects

K Murakami

Publications and source records attributed to K Murakami.

At least 649 records · Page 36Linked to original sources
PubMed1993

Satisfactory separation and MS-MS spectrometry of six surfactins isolated from Bacillus subtilis natto.

We optimized HPLC conditions for the first time to achieve satisfactory separation of six surfactins, two of which were novel, isolated from Bacillus subtilis natto. Peptide sequences were analyzed by sophisticated MS-MS analysis, performed with a pair of two surfactins with different fatty acid substitutions. Fragment peaks were divided into two series; one was a series of the ions which carried fatty acid, and thus were characterized by the fatty acid mass difference, and the other was a series of the ions which consisted of pure peptide and thus showed a superimposable pattern between a pair of surfactins.

Amino Acid Sequence↗
PubMed1993

Synthesis and characterization of 11C-labeled fluoroclorgyline: a monoamine oxidase A specific inhibitor for positron emission tomography.

A new radioligand for monoamine oxidase type A (MAO-A), [11C]fluoroclorgyline, was synthesized from its desmethyl precursor by N-methylation reaction using [11C]methyl iodide with a radiochemical yield of 75-85%. The radiochemical purity of the product was more than 99% and the specific radioactivity was 7.4-18.5 GBq/micromol. The in vivo tissue distribution studies of [11C]fluoroclorgyline in mice demonstrated its high initial uptake and prolonged retention in the brain, comparable to those of [11C]clorgyline. A selective interaction with MAO-A in the accumulation of [11C]fluorclorgyline was confirmed by a competition experiment performed with the MAO-A specific inhibitor,clorgyline, and MAO-B specific inhibitor, l-deprenyl. These very desirable characteristics of [11C]fluoroclorgyline suggested that its 18F labeled counterpart, [18F]fluoroclorgyline, would have great potential as a longer-lived alternative to 11C labeled clorgyline for in vivo studies of MAO-A in the human brain with positron emission tomography (PET).

Animals↗
PubMed1993

A simple method of hybridohistochemistry for detection of renin mRNA in the mouse kidney.

Hybridohistochemistry was applied for the detection of renin mRNA in the mouse kidney with a digoxigenin-labeled probe, synthesized as the sense and antisense RNAs from Ren-1 cDNA in the presence of digoxigenin-dUTP. Renin mRNA was detected in the juxtaglomerular cells located in the vicinity of the glomerular vascular poles of the kidney using the digoxigenin-labeled antisense RNA as a probe. Using the sense RNA as a probe, no signal was detected anywhere. In neighboring serial sections, the same cells reacted immunohistochemically to rabbit anti-mouse submandibular gland renin serum as in hybridohistochemistry. As we used the probe labeled with digoxigenin as a non-radioisotopic marker, there was no need for special handling other than that in immunohistochemistry. It was concluded that the simple procedure given in the present study is useful for the detection of mRNA.

Animals↗
PubMed1993

Rat renin promoter activity in cultured cells and transgenic mice.

Renin, a key enzyme controlling blood pressure, is mainly synthesized in kidney. To characterize the rat renin promoter, we have constructed a reporter gene containing the 238-bp putative regulatory region linked to a bacterial chloramphenicol acetyltransferase (CAT), and analyzed its promoter activity by in vitro transfection and introduction of the CAT fusion gene into germline of mice. CAT activity was detected in transfected embryonic kidney-derived 293 cells, but not in HeLa cells derived from cervical carcinoma, showing that the putative promoter region of the rat renin gene directs transcription in a cell type-dependent manner. To examine whether the sequence was sufficient to regulate the expression of the CAT chimeric gene in mice, we generated seven transgenic mice carrying the reporter construct. Unexpectedly, the transgene was not expressed in any of the independent transgenic mice examined. These results suggest one possibility that an additional control region may be required for efficient expression of the rat renin promoter in developing mice.

Animals↗
PubMed1993

Morphogenesis of compound melanosomes in melanoma cells of a gray horse.

A thoroughbred horse, gelding, gray color, aged 19 years old had cutaneous melanomas from the root to the middle of the tail, and throughout the connective tissues of the whole body. Histologically, the tumors were diagnosed as mature melanotic melanomas characteristically deposited with abundant melanin pigment. Examined with an electron microscope, melanosomes were electron opaque without internal structure (stage IV), or as mature granular and lamellar types. Most of them were fused with each other, and formed compound melanosomes, which was similar to internal melanin aggregates in shape. The internal melanin aggregates gradually disintegrated, and compound melanosomes grew spherical. The compound melanosomes changed into autophagosomes.

Animals↗
PubMed1993

Adrenal steroids in serum during danazol therapy, taking into account cross-reactions between danazol metabolites and serum androgens.

To investigate the changes in the serum androgen concentrations and the Free Androgen Index (FAI) in women during danazol therapy, we measured the serum concentrations of adrenal steroids and danazol metabolites, and then examined the effects of danazol metabolites on assays for serum androgens. Thirteen women who had endometriosis were treated with danazol (300 or 400 mg/day) for 8 to 16 weeks. Blood samples were taken before, during, and after the medication. During the danazol therapy, serum testosterone (T), cortisol (F), and sex-hormone binding globulin (SHBG) significantly decreased (P < 0.05); but serum dehydroepiandrosterone-sulfate (DHEAS) and FAI increased (P < 0.05). The serum concentrations of danazol metabolites were: danazol, 209.0 +/- 28.3 (ng/mL, mean +/- SEM); delta 1-2-hydroxymethyl ethisterone, 114.4 +/- 8.4; and 2-hydroxymethyl ethisterone, 660.0 +/- 54.2. There was considerable cross-reaction between danazol metabolites and androgens [T, androstenedione (A), and dehydroepiandrosterone (DHEA)] in the direct assays. As for the ratios of adrenal steroids in serum, the DHEAS/F, DHEAS/DHEA, and 11-deoxycortisol (S)/F ratios increased (P < 0.05). We conclude that the increase in FAI and DHEAS represents increased native androgenic activity with danazol, and the changes in adrenal steroid ratios in serum indicate the inhibition of 11 beta-hydroxylase and sulfatase activities during danazol therapy.

Adrenal Glands↗
PubMed1993

Production of transgenic rats using pregnant and pseudopregnant rats prepared at a breeding farm.

We used pregnant and pseudopregnant Wistar-Imamichi rats, prepared at a breeding farm, for production of transgenic rats. The donor and recipient rats were transported to our facility for ova manipulation and embryo implantation, respectively. As a foreign gene, 1.9 kb of a hybrid gene was constructed with the rat renin promoter and chloramphenicol acetyltransferase-coding gene. Fertilized oocytes were collected from the donor and the foreign DNA was microinjected into the pronuclei of 539 oocytes by the method of Hochi. The manipulated oocytes were cultured to the 2-cell stage. One hundred seventeen 2-cell embryos were implanted in the recipient rats. Of 67 newborns, 55 rats grew up to be 3-week-old weanlings. Genomic DNA was extracted from the tail of these weanlings and examined by polymerase chain reaction analysis. Six transgenic rats were found to have been generated by the present method. In this way, transgenic rats were produced by an efficient combination of breeding farm utilization and laboratory research.

Animals↗
PubMed1993

Effect of FK506 on the development of diabetes in BB rats in comparison with that of cyclosporin.

FK506, a agent extracted from a streptomyces, has more potent immunosuppressive properties compared with cyclosporin in vitro. We compared the preventive effect of FK506 on the development of diabetes mellitus with that of cyclosporin in BB rats, which are regarded as a useful model of insulin-dependent diabetes mellitus. BB rats aged 30 days were treated intramuscularly with FK506 (0.1 mg/kg/day and 0.32 mg/kg/day) or with cyclosporin (10 mg/kg, alternate days) until 150 days of age. Diabetes developed in 2 (10.5%) of 19 rats treated with the lower dose of FK506 and none of 20 rats with the higher dose of FK506; on the other hand, 1 (5.3%) of 19 rats treated with cyclosporin developed diabetes. In contrast, 9 (36.0%) of 25 control rats became diabetic. The cumulative incidence of diabetes mellitus in the group treated with FK506 (0.32 mg/kg) showed a decrease similar to or more than that of the cyclosporin-treated group. Histological examination showed that FK506 and cyclosporin prevented the reduction in the average size of islets and in the area of beta cells. The analysis of lymphocyte subsets proved the decrease of W3/25: OX8 ratio in both FK506- and cyclosporin-treated groups. These data suggest that the administration of FK506 might be a more useful tool for preventing the development of insulin-dependent diabetes mellitus.

Aging↗
PubMed1993

Apolipoprotein E polymorphism is associated with plasma cholesterol response in a 7-day hospitalization study for metabolic and dietary control in NIDDM.

OBJECTIVE: To investigate the effects of apolipoprotein E phenotype, which is an important genetic factor determining plasma cholesterol level, on plasma lipoprotein metabolism during a 7-day diet therapy of diabetes. RESEARCH DESIGN AND METHODS: Diet therapy was performed in 242 subjects with NIDDM. Plasma lipid levels and apolipoprotein A-I, B, and E levels on hospital days 2 and 9 were compared in three phenotype groups, epsilon 2 (E2/2, and E2/3), epsilon 3 (E3/3), and epsilon 4 (E3/4 and E4/4). RESULTS: No differences were observed in fasting blood glucose level, body mass index, age, duration of NIDDM, or medication among the three phenotype groups. Before starting the treatment, total plasma cholesterol did not vary by apolipoprotein E phenotype, although the mean plasma low-density lipoprotein cholesterol level in epsilon 4 patients was higher than in either epsilon 3 or epsilon 2 patients (epsilon 4, 145 +/- 42; epsilon 3, 131 +/- 34; epsilon 2, 128 +/- 36 mg/dl; P < 0.05). Changes in fasting blood glucose/body mass index after the 7-day treatment were not different among the apolipoprotein E phenotype groups, whereas the decrease in plasma cholesterol level after the treatment was significantly greater in epsilon 2 patients than in either epsilon 3 or epsilon 4 patients (epsilon 2, 10.3 +/- 14.2; epsilon 3, 6.1 +/- 11.0; epsilon 4, 3.8 +/- 9.6%; P < 0.05). CONCLUSIONS: Total plasma cholesterol response to in-hospital diet therapy varies by apolipoprotein E phenotypes, with subjects with apolipoprotein E2 showing the greatest response, whereas those with apolipoprotein E4 show the least. We suggest that subjects with apolipoprotein E4 should be controlled more strictly than other subjects from a viewpoint of reducing plasma cholesterol levels.

Alleles↗
PubMed1993

Presence of high molecular weight forms of BMP-2 in early Xenopus embryos.

Using polyclonal antibodies which recognize 18 kDa BMP-2, we have previously demonstrated that the major BMP-2 protein in Xenopus embryo extracts is monomeric and not dimerized whereas, the mammalian counterpart derived from bone extract was purified as a dimeric protein. In this study, the same antibodies (Ab383) were used to detect high molecular weight forms of Xenopus BMP-2. Partial purification of the immunoreactive 18 kDa BMP-2 from Xenopus embryo extract by gel filtration, heparin-Sepharose affinity chromatography and preparative SDS-PAGE resulted in co-purification and identification of higher molecular forms of BMP-2 of 110 kDa and 36 kDa. Diagonal SDS-PAGE analysis suggested that they are homodimer and multimer of the 18 kDa species, respectively, linked through disulfide bridge(s).

Animals↗
PubMed1993

Immunodetection of Xenopus bone morphogenetic protein-4 in early embryos.

Specific antibodies to Xenopus laevis bone morphogenetic protein-4 (xBMP-4) were raised by immunizing rabbits with a fusion protein of bacterial beta-galactosidase and xBMP-4. The antibodies were used to detect xBMPs expressed in mammalian cells by Western blotting. The antibodies were found to recognize xBMP-4 specifically and not to cross-react with either xBMP-2 or xBMP-7 which are similar to xBMP-4. In addition, the antibodies recognized dimeric xBMP-4 whereas our previous antibodies recognized the reduced form only. The present antibodies detected an immunoreactive 27 kDa protein in extracts of developing Xenopus embryos from oocyte to tailbud embryo. The xBMP-4 peptide appeared to be monomeric in structure because the molecular weight did not shift upon reduction of disulfide bond(s).

Amino Acid Sequence↗
PubMed1993

[Expression of fibronectin receptor and vitronectin receptor in diseased human kidneys].

Expression of fibronectin and vitronectin receptors was studied in normal human kidney tissues and renal tissue biopsies from patients with several types of glomerulonephritis. Immunofluorescent staining of the normal kidneys showed that fibronectin receptor was present along the glomerular capillary walls, and that vitronectin receptor was present in the vessel walls, but was almost absent from the glomerulus. In kidney tissues biopsied from patients with various renal diseases, expression of fibronectin and vitronectin receptors was correlated with increase in the mesangial expansion. Expression of these receptors was decreased in the sclerosed area and hyalinized glomeruli compared with normal tissues. Fibronectin and vitronectin receptors were occasionally colocalized in the glomeruli with fibronectin and vitronectin, respectively. In situ hybridization showed that fibronectin receptor mRNA and vitronectin receptor mRNA were expressed in the diseased glomeruli. These findings indicate that expression of fibronectin and vitronectin receptors was altered in human glomerulonephritis, and that integrin expression may be important in cell-matrix interaction in the diseased glomeruli.

Glomerulonephritis↗
PubMed1993

Synaptic organization and prefrontal corticothalamic termination in the mediodorsal thalamic nucleus of the cat.

The synaptic organization of the mediodorsal thalamic nucleus (MD) in the cat have been studied with the electron microscope, and correlated with the termination of the medial prefrontal corticothalamic afferents using the method of anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). The neuropil of MD was divided into glomerular and extraglomerular regions. A synaptic glomerulus was composed of a central dendrite and some different presynaptic profiles with astroglial ensheathment. The prevalent presynaptic elements in glomeruli were presynaptic dendrites (PSDs) that contained pleomorphic vesicles, and formed symmetric synaptic contacts and puncta adhaerentia junctions with central dendrites. One or two large terminals with round vesicles and asymmetric specializations (LR) also participated in glomerular formations. They were invariably presynaptic to central dendrites and PSDs. As terminals less frequently found within glomeruli, there were small-sized terminals with round vesicles and asymmetric synaptic junctions with PSDs. In the extraglomerular neurophils, small to medium-sized terminals with pleomorphic vesicles (SMP) were found besides the presynaptic profiles identified in glomerular regions. These SMP terminals formed axodendritic and axosomatic symmetric synapses. WGA-HRP injections into the medial prefrontal cortex resulted in anterograde labelings in not only SR but also LR presynaptic terminals. SR boutons made up the majority of labeled terminals, and they were found only in the extraglomerular neuropil. While labeled LR terminals were detected in the extraglomerular neuropil and synaptic glomeruli with less encounter. The results of the present study show that the synaptic organization in MD of the cat is similar to that in other thalamic relay nuclei and in MD of the monkey. Further, MD receiving two subsets of synaptic terminations from the prefrontal cortex might play a different functional role in regulating the neural circuit between MD and the prefrontal cortex in comparison with that in the sensory and motor thalamic nuclei that receive only SR terminals from the sensorimotor cortex.

Animals↗
PubMed1993

Differential expression of Xenopus BMPs in early embryos and tissues.

Expression levels of mRNA for Xenopus bone morphogenetic proteins (BMPs) in early embryos and adult organs were examined. Reverse transcription-polymerase chain reaction (RT-PCR) that used specific primers for each BMP subtype revealed that mRNAs for BMP-2 and BMP-4 are distributed in a wide variety of adult tissues including lung, heart, and kidney. Unexpectedly, distribution of mRNA for BMP-7 was found to be limited to ovary and early embryos. The result suggests that Xenopus BMP-7 may have a specific role in ovary and early embryos.

Animals↗
PubMed1993

A new determination method of network chain-length distribution of rubber vulcanizates by chemorheology.

The structural changes of material caused by chemical reaction are reflected in the viscoelastic properties of these substances. Such a viscoelastic property induced by chemical reaction was termed chemorheology. Therefore, chemorheology is a relatively new discipline encompassing the physical and chemical aspects involved in the elucidation of the mechanisms, at a molecular level, of structural changes of polymers during their degradation. The studies presented here are the results stimulated further research in areas where this new determination will be more developed.

Benzyl Compounds↗
PubMed1993

A new approach to collagen fiber orientation in cow skin by the microwave method.

The fiber orientation of cow leather sheets corresponding to the corium of the middle layer in the cow skin was studied by measuring the angular dependence of transmitted microwave intensity and the complex dielectric constant at a microwave frequency of 3.9 GHz. The direction of the minimum transmitted microwave intensity and the maximum dielectric loss agrees with that of the maximum mechanical breaking strength, suggesting that the collagen fibers constituting the cow leather should be preferably oriented in the direction of minimum transmitted microwaves and the maximum dielectric loss. The electron microphotograph supported this suggestion. The main chain direction of collagen fibers and the degree of orientation varied from position to position in the sheet. The present microwave method is convenient for quick determination of the orientation of collagen fibers in the cow skin. It can be applied non-destructively and contact-freely.

Animals↗
PubMed1993

[Eradication therapy of Helicobacter pylori in gastroduodenal ulcer and its long-term course].

We investigated the efficacy of antimicrobial drugs, amoxicillin and clarithromycin that have the in vitro activity against H. pylori, and observed a long term course of ulcer after eradication. The eradication rate of combination therapy with PPI and amoxicillin showed best result (13/18: 72%). In eradicated cases, index of PAS positive substance and gastritis score in antral mucosa that is histological examination was improved, and ammonia concentration in gastric secretions decreased. The recurrent rate of ulcer in long term course after eradication was investigated, the recurrent rate of ulcer was significantly lower in H pylori eradicated cases than in H. pylori continuously positive cases. Results suggest that eradication of H. pylori may be controlled recurrence of H. pylori positive peptic ulcer.

Amoxicillin↗