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Biomedical subjects

M Iwaki

Publications and source records attributed to M Iwaki.

At least 109 records · Page 6Linked to original sources
PubMed1994

Insulin-like growth factor-I messenger RNA content in the oviduct of Japanese quail (Coturnix coturnix japonica): changes during growth and development or after estrogen administration.

Complementary DNA (cDNA) of insulin-like growth factor-I (IGF-I) of Japanese quail was cloned. The nucleotide sequence analysis of the cDNA showed that only seven bases differed from those of chicken IGF-I cDNA in the 440 bases of the cloned region. This difference in nucleotide sequence did not cause changes in the amino acid sequence. Using this cloned cDNA, the changes in IGF-I mRNA content in the tissues of female quail during growth and development were investigated. In the oviduct, IGF-I mRNA was high about 5 weeks after hatching, concomitant with the rapid increase in total DNA content in this tissue (and the increases in total RNA content and RNA/DNA ratio). It decreased after 6 weeks, in accordance with the appearance of ovalbumin mRNA. When immature quails (6-day-old) were injected with diethylstilbestrol (DES), induction of IGF-I mRNA was observed after 24 hr. A few days later, there was a strong induction of ovalbumin mRNA. These two inductions were dependent on the dose of DES. The sequential inductions of these two mRNAs were also noted when DES was re-administered to the immature quail to which it had been first administered and from which then withdrawn. The present results showed that IGF-I gene is expressed extensively during development of the oviduct, probably in accordance with the activity of DNA replication, because the highest IGF-I mRNA content was observed when the total DNA content of the tissues increased extensively. The results suggest that IGF-I in the oviduct of Japanese quail works in an autocrinal or paracrinal mode during the development of this tissue.

Amino Acid Sequence↗
PubMed1994

Antigenic relationship between the house dust mite Dermatophagoides farinae and the predacious mite Phytoseiulus persimilis.

We have examined the antigenic relationship between the house dust mite Dermatophagoides farinae and the predacious mite Phytoseiulus persimilis. Immunoblotting analysis demonstrated that there was a very weak antigenic cross-reactivity between these different suborder of mites but that this cross-reactivity was not attributed to D. farinaes major allergen's, Der fI and Der fII. These results suggest that P. persimilis might scarcely provoke allergic symptoms in patients sensitized to house dust mites.

Animals↗
PubMed1993

Aflatoxin B1-binding proteins in primary cultured hepatocytes of chicken embryo: studies in vivo and in vitro.

Among several aflatoxin B1 (AFB1)-binding proteins in primary cultured hepatocytes of chicken embryo, a cytosolic 25 kDa protein proved to be an AFB1-specific binding protein. Binding of AFB1 to a cytosolic protein of the same molecular mass as that seen in vivo was also detectable in a cell-free system and was dependent on the microsomal components. The binding was observed in the in vitro systems derived from AFB1-sensitive animals such as chicken, rabbit, and rat. These findings suggest that the 25 kDa AFB1-binding protein(s) is involved in the intracellular process of AFB1-mediated toxicity.

Aflatoxin B1↗
PubMed1993

Selective adhesion and proliferation of cells on ion-implanted polymer domains.

We have found that the adhesion and proliferation of endothelial cells can be drastically improved when cultivated on an ion-implanted polymer surface. When the surface of segmented polyurethane, where endothelial cells are not capable of proliferating, is modified by Ne+ or Na+ ion implantation with a fluence of 1 x 10(15) ions/cm2 at an energy of 150 keV, cell adhesion and proliferation occurred selectively on the ion-implanted region irrespective of the ion species. The cells did not proliferate at ion fluences below 1 x 10(14) ions/cm2. Most cells migrated into the ion-implanted domain within 1-2 h, but some of the cells attached outside of the region and then slowly migrated into the region. Ion implantation of polystyrene, on which cells are capable of proliferating, further promoted cell spreading and proliferation, and increased resistance to detachment when the cells were exposed to trypsin.

Animals↗
PubMed1993

Trypsin-like protease of mites: purification and characterization of trypsin-like protease from mite faecal extract Dermatophagoides farinae. Relationship between trypsin-like protease and Der f III.

A serine protease from mite faecal extract, Dermatophagoides farinae, was purified using DEAE-Sephacel anion exchange chromatography and Superdex 75 pg gel chromatography. The molecular weight of this protease was 34 kD on SDS-PAGE under reducing conditions. The optimal pH and temperature of the protease were 8.0 and 47 degrees C, respectively. In addition, this protease cleaved arginyl or lysyl residue containing substrates selectively and was only inhibited by aprotinin, FUT-175, and soy bean trypsin inhibitor and not by chymostatin, E-64 and iodoacetic acid. These results show that our purified serine protease belongs to the trypsin-type. Purified trypsin-like protease was shown to be allergenic by enzyme-linked immunosorbent assay. Antigenicity of trypsin-like protease was completely different from those of Der f I and Der f II. Both, 20 N-terminal amino acid sequence and amino acid compositions of the purified protease were very similar to those of Der f III. Good similarities were found between trypsin-like protease and Der f III concerning physicochemical properties such as molecular weight on SDS-PAGE and ammonium sulphate solubility. Summarizing the above data, it can be concluded that a trypsin-like protease from mite faecal extract is actually the Der f III allergen and that it may be involved in the digestive process of the mite as it was found not in mite body but in mite faeces.

Adolescent↗
PubMed1993

Pharmacokinetic analysis of phenytoin and its derivatives in plasma and brain in rats.

The derivatives of phenytoin (DPH) were synthesized by the reaction at 3 position of hydantoin ring with valproic acid and valeric acid, producing valproyl DPH (VPDPH) and valeroyl DPH (VADPH), respectively. These derivatives showed much higher lipid solubilities than that of DPH. Their distribution and elimination were compared to those of DPH. Additionally, the concentration profiles of the drugs in brain and plasma were analyzed with a modified 2-compartment model. DPH and its derivatives, without hydrolysis to DPH in blood, were found rapidly distributed into brain, although the distribution of derivatives was much less, probably due to the high protein binding capacities. The distribution of DPH and its derivatives into brain regions was similar to that into the cortex cerebri. VPDPH and VADPH were more rapidly eliminated from plasma and brain than DPH, giving smaller mean residence time (MRT) values (0.92 and 0.85 h) and much smaller cortex/plasma concentration ratio than those of DPH. The VPDPH and VADPH concentrations in the cerebrospinal fluid (CSF) were also much lower than that of DPH. The time course of plasma and brain concentrations of DPH and its derivatives after i.v. administration was successfully described by the modified 2-compartment models presented.

Animals↗
PubMed1993

Pharmacokinetics of cyproheptadine and its metabolites in rats.

To investigate the pharmacokinetics of cyproheptadine (CPH) and its metabolites, the plasma concentration and urinary excretion of CPH and its detectable metabolites were determined after intravenous (i.v.) administration of parent or synthesized metabolites to rats. The plasma CPH concentration-time course was subjected to biexponential calculation following the i.v. administration of CPH, producing the temporal and low plasma concentrations of desmethylcyproheptadine (DMCPH) and the sustained plasma concentrations of desmethylcyproheptadine-epoxide (DMCPHepo). DMCPH was also eliminated, according to the biexponential equation, after i.v. administration of performed DMCPH, forming DMCPHepo in plasma. On the other hand, no detectable DMCPHepo was found in plasma after the i.v. administration of cyproheptadine epoxide (CPHepo). All compounds administered had large distribution volumes and were almost entirely excreted as DMCPHepo in urine; this excretion continued for a long time. However, the urinary excretion pattern of DMCPHepo after CPHepo was different from those after CPH and DMCPH. The mean residence times of the epoxidized metabolites estimated from the urinary data were much longer than those from the plasma concentration data, suggesting either a gradual reflux of the metabolites from a tissue depot into systemic circulation under those plasma concentrations close of detection limit, or some interaction which delays excretion into the urine. This study suggests that both metabolic pathways of CPH, through DMCPH and CPHepo, to DMCPHepo are possible, but that the demethylation of CPH largely occurs prior to epoxidation; also that the extensive and persistent distribution of DMCPHepo to tissues may relate to the toxicity of CPH reported in rats.

Animals↗
PubMed1993

Effect of mexiletine on elimination and metabolic conversion of theophylline and its major metabolites in rats.

In an attempt to clarify the possible mechanism of the interaction between theophylline (TP) and mexiletine (ME), the elimination kinetics and in vitro metabolism of TP and its metabolites were investigated in rats. The plasma elimination of TP, 1,3-dimethyluric acid (1,3-DMU) and 1-methyluric acid (1-MU) was significantly delayed by the intravenous (i.v.) administration of ME. The oral administration of ME also decreased the elimination rate of TP to the same extent as the i.v. dosing. The in vitro metabolic experiment showed that ME significantly inhibited the metabolic conversion of TP to 1,3-DMU and, 1,3-DMU to 1-MU, and slightly inhibited the conversion of TP to 3-methylxanthine, these processes being mediated by microsomal enzymes, with no inhibition of xanthine oxidase. Our results indicated that ME could inhibit the metabolic conversion of TP and its metabolite in rat, as reported in man.

Administration, Oral↗
PubMed1993

Rectal absorption of acyclovir in rats and improvement of absorption by triglyceride base.

The rectal absorption of acyclovir has been evaluated after administration of suppositories without absorption enhancers in rats. The disappearance of plasma acyclovir followed biexponential kinetics after i.v. dosing. Rectal administration of a triglyceride (Vosco S-55 and Vosco S-55 + methylcellulose) suppository gave relatively high plasma concentrations and bioavailabilities (95.3 and 83.4%, respectively) compared with Witepsol and macrogol suppositories. However, the in vitro release profiles from suppositories did not accurately reflect plasma concentrations after rectal dosing. Our results suggest that the rectal administration of acyclovir suppositories may be a promising substitute for intravenous infusion, which is at present used for the treatment.

Acyclovir↗
PubMed1993

Percutaneous absorption of acemetacin from a membrane controlled transdermal system and prediction of the disposition of the drug in rats.

To avoid development of a lesion on the small intestine by acemetacin (ACM) following oral administration of the drug, we developed a new device for its percutaneous application. The device for transdermal application of ACM consisted of a silicon O-ring, a backing of aluminum foil and adhesive tape, and rate-controlling membranes with three different pore sizes (HP-1100, 2100 and 4050). Two percent ACM gel ointment was contained in the device. In the in vitro release experiment, the ACM release from the device was limited by these membranes with release rate constants of 0.630 +/- 0.052, 0.289 +/- 0.012, 0.098 +/- 0.11 and 0.083 +/- 0.011 h-1 for no membrane, HP-4050, HP-2100 and HP-1100 membranes, respectively. In the in vitro penetration experiment, the ACM penetrating through the skin appeared in the reservoir cell without the metabolic conversion to indomethacin (IM). After the application of the ACM device with the HP-2100 rate-controlling membrane on the rat abdominal skin, ACM was not detected in the plasma but the therapeutic plasma concentration of IM could be maintained over a 54 h period. These results indicate that the device with a rate-controlling membrane may be useful for the percutaneous application of ACM as an anti-inflammatory drug and its clinical application. For the percutaneous absorption of ACM after application of the ACM devices, the values estimated by the proposed model which consisted of 6 compartments well fit to the data obtained from this in vivo experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1993

Effectiveness of the elcatonin transdermal system for the treatment of osteoporosis and the effect of the combination of elcatonin and active vitamin D3 in rat.

The efficacy of percutaneous elcatonin (EC), a hypocalcemic peptide, in the treatment of experimental osteoporosis in rats was evaluated in vivo. Additionally, the effect of the combined use of EC and active vitamin D3 (1,25(OH)2D3) for the treatment was compared with those of three other groups: 1,25(OH)2D3 alone, estradiol plus 1,25(OH)2D3, and a placebo, and low calcium diet (low Ca). The EC transdermal system and the EC plus 1,25(OH)2D3 system, applied to the rat abdominal skin 6 times for 48 h, significantly increased the ash weight and calcium content of the tibia in the rats, compared with those of placebo group (p < 0.05). The EC systems also slightly lowered the alkaline phosphatase activity in plasma of the morbid rats, without a difference in the plasma calcium content. These EC systems were superior to the 1,25(OH)2D3 system and the estradiol plus 1,25(OH)2D3 system in improving osteoporotic parameters. Thus, the EC systems were concluded to be an efficient drug delivery system for Paget's disease and osteoporosis.

Administration, Cutaneous↗
PubMed1992

Photoaffinity labeling of the phylloquinone-binding polypeptides by 2-azidoanthraquinone in photosystem I particles.

A photoaffinity label, 2-azido-9,10-anthraquinone, binds at the quinone-binding (Q phi) site with high affinity and can substitute for the secondary acceptor, phylloquinone, in photosystem I reaction center of spinach. Phylloquinone-depleted photosystem I particles reconstituted with azido[3H]anthraquinone were illuminated with UV light and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The large core polypeptides (psaA and/or psaB) were selectively labeled. The labeling was competitively inhibited in the presence of anthraquinone. These results indicate that the Q phi site is located on psaA or psaB polypeptides.

Affinity Labels↗
PubMed1992

Enhancement of percutaneous absorption by laurocapram.

The in vitro treatment of shed snake skin and hairless rat skin with laurocapram resulted in dramatic decreases in the amounts of cholesterol, phospholipids, and ceramides but not triglycerides in the skins. Scanning electron microscopic observations of hairless rat skin treated with laurocapram indicated looseness and cell separation of the stratum corneum probably caused by the extensive extraction of the intercellular lipids. An ESR study demonstrated the increased fluidity of the corneum lipids after laurocapram treatment. The apparent rotational correlation time of 16-doxyl-stearic acid was decreased by 1.6-2 times after treatment with laurocapram. No penetration of laurocapram itself through shed snake skin and hairless rat skin was detected in vitro, except when the reservoir solvent was 60% ethanol or propylene glycol. The enhancer was hardly metabolized during a 48-h incubation with skin homogenate. Pretreatment of shed snake skin with laurocapram increased significantly the penetration of sulfanilamide and indomethacin through the skin. These results indicate that laurocapram penetrating into the stratum corneum interacts with structured lipids in the intercellular channels and releases them, thereby enhancing the penetration of hydrophilic drugs through the channels. Additionally, laurocapram penetrating into the intracellular matrix of the corneum fluidizes the intracellular lipids and causes the reduction of diffusional resistance.

Administration, Cutaneous↗
PubMed1992

Scanning electron microscopy of eggs of Mansonia bonneae (Diptera: Culicidae).

The egg of Mansonia bonneae (Edwards) is described by means of scanning electron microscopy (SEM) and compared with other sympatric species reported recently in previous studies. Ma. bonneae differed from Ma. uniformis (Theobald), Ma. indiana (Edwards), Ma. annulifera (Theobald), and Ma. annulata (Leicester) in that it has six variably sized dog-tooth spines surrounding the raised central micropyle, and only a single nipplelike stud at the anterior one-third of the egg. A key for identification of the eggs of the five sympatric Mansonia species under SEM is presented.

Animals↗
PubMed1992

Increased monoamine turnover in the subfornical organ area following body fluid depletion.

To clarify whether monoaminergic inputs to the subfornical organ (SFO) area participate in fluid regulatory systems, we examined the effects of body fluid depletion on monoamine turnover in the region of the SFO using microdialysis techniques in rats. An iso-osmotic reduction of fluid volume following subcutaneous treatment with polyethylene glycol (PEG) significantly increased dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in the SFO area. 5-hydroxytryptamine (5-HT) in the SFO area could be detected after the PEG treatment, while 5-HT was undetectable before the treatment. The data imply that both dopaminergic and serotonergic systems in the SFO area may be involved in controlling body fluid balance.

Animals↗
PubMed1992

Simple and accurate assay for tyrosine hydroxylase from bovine retina by high-performance liquid chromatography with fluorescence detection.

We present a simple and sensitive assay for tyrosine hydroxylase (TH) using high-performance liquid chromatography (HPLC) with a fluorescence detector which enabled us to study bovine retinal TH of a small quantity in crude retinal samples. The detection limit with this method was 1 pmol of dihydroxyphenylalanine (DOPA) enzymatically produced. Retinal TH exhibited the maximum activity at pH 6 to 6.3, and almost none at physiological pH of above 7, a tendency similar to that reported for striatal TH.

Animals↗