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Biomedical subjects

Y Machida

Publications and source records attributed to Y Machida.

At least 109 records · Page 6Linked to original sources
PubMed1989

Plasma levels following intranasal and intravenous administration of human interferon-beta to rabbits.

Rabbits were given single doses (2 x 10(6) IU) of human fibroblast interferon (HuIFN-beta) by the following routes of administration: (a) intravenous injection, (b) dropwise intranasal administration of a liquid dosage form, and (c) spraywise intranasal administration of a powder dosage form. Following the intravenous injection, plasma HuIFN-beta concentrations declined rapidly in a biphasic manner in agreement with a two-compartment model, whilst concentrations following the intranasal administrations conformed to a one-compartment model. Maximum plasma levels and the areas under the plasma concentration-time curve (AUC) in response to dose were studied in the case of the spray administration, and found to be proportional to dose. The systemic bioavailability of HuIFN-beta (administered with sodium glycocholate and excipients) via the nasal routes was about 3% of that via the intravenous route. The elimination half-lives did not differ significantly between these two routes of administration.

Administration, Intranasal↗
PubMed1989

Preparation and evaluation of intragastric buoyant preparations.

The design and preparation of two drug formulations which float in gastric juice are described. One, a buoyant tablet, consisted of powdered soybean protein, drug and sodium bicarbonate. The other, a laminated film-type preparation, consisted of a drug film, an effervescing film containing sodium bicarbonate and outer drug release regulating films. Cinnarizine, an acid-soluble drug, was chosen as model drug, and carboxyvinyl polymer, ethyl cellulose and hydroxypropyl cellulose were used in the preparation of the films. Both formulations showed favorable buoyancy in an in vitro acidic dissolution test medium and also sustained release properties. In an absorption study using beagle dogs, cinnarizine was found in the blood even 24 hr after oral administration of the buoyant tablet or film-type preparation. Similar buoyant tablets containing barium sulfate were administered orally to a healthy volunteer, and it was confirmed by roentgenography that the tablets floated for almost three hours.

Administration, Oral↗
PubMed1989

Buoyant sustained release granules based on chitosan.

Attempts to develop sustained release intragastric 'floating' granules based on chitosan are described, using chitosan of different degrees of deacetylation (chitosan H and L), in granular form or in laminated preparations. The granules were made from chitosan H (chitosan H granules), from a 1:1 mixture of chitosan H and L (1:1 mixture granules), from a 1:2 mixture of chitosan H and L (1:2 mixture granules), or from chitosan L (chitosan L granules). They were prepared by a method involving deacidification, had internal cavities, were immediately buoyant in both acidic and neutral fluids, and gave sustained release of prednisolone (used as a model drug). The laminated preparations, composed of a chitosan granule layer and a chitosan L membrane, were also immediately buoyant in the same fluids, and also provided sustained release of the model drug. The release properties were controlled by regulating the chitosan L content of the granules, or the chitosan L membrane thickness of the laminate. In an absorption study using beagle dogs, sustained drug absorption from these preparations was obtained.

Animals↗
PubMed1988

Right-hand border regions of octopine T-DNA are recognized by RNA polymerase of Agrobacterium as well as by VirD1 and VirD2 proteins.

The T-DNA of octopine Ti plasmid of Agrobacterium tumefaciens contains TL- and TR-DNA regions each bounded by 25 base-pair-repeats (designated A, B, C and D from left to right). Short DNA segments containing the borders B, C and D were found to function as promoter when placed in the rightward orientation upstream of promoter-less lacZ. Promoter consensus sequence of Agrobacterium were found within these border repeats and in their adjacent regions. The expression of lacZ was low when the segments contained the overdrive, a sequence known to enhance T-DNA transfer. Simultaneous overproduction of VirD1 and D2 proteins, endonuclease acting on the border repeats, interfered with the promoter functions of the border segments. In spite of their activity under these conditions, the border regions do not seem to be involved in the gene expression, because they are not followed by appropriate open reading frames. We propose that RNA polymerase of Agrobacterium competes with VirD products for T-DNA borders and thereby affects the transfer of T-DNA.

Arginine↗
PubMed1988

Escherichia coli lacZ gene as a biochemical and histochemical marker in plant cells.

Several lacZ chimeric genes were constructed by fusing the truncated lacZ sequence of Escherichia coli to N-terminal sequences of few other genes. Promoters used to direct expression of the chimeric genes were the promoter for 35S RNA of cauliflower mosaic virus (P35S) as well as those of the small subunit gene of ribulose bisphosphate carboxylase and the octopine synthase gene. These constructs were introduced into tobacco cells using a Ti plasmid of Agrobacterium tumefaciens, and beta-galactosidase activity in uncloned and cloned calli derived from the crown galls were examined. The results showed that the P35S-linked lacZ chimeric gene is expressed very efficiently. When slices of the crown gall carrying this chimeric gene were placed on plates containing indicator XGal, localized areas of the outgrowth turned deep blue, whereas no such areas were found in the crown gall having promoter-less lacZ. Calli from galls containing this construct expressed beta-galactosidase activity at an eight-fold higher level (approx. 7000 units/mg protein) than the endogenous activity (approx. 900 units/mg protein). Some of the calli displayed over 20-fold higher activity. Actively growing mini calli expressing activity higher than 4000 units/mg protein dyed deep blue on XGal agar medium such that they were distinguishable from calli having no lacZ. Half of the uncloned P35S-lacZ transformant calli showed activity higher than this level. These results indicate that the lacZ gene linked to a strong promoter such as P35S is useful as a biochemical and histochemical marker gene in plant cells.

Chromosome Mapping↗
PubMed1988

Subcellular localization of tobacco mosaic virus minus strand RNA in infected protoplasts.

Radioactive RNA probes were prepared which specifically hybridize with sequences complementary to 5' and 3' regions of tobacco mosaic virus (TMV) RNA. These probes were used in Northern hybridization to locate TMV-RNA minus strands in the subcellular fractions of infected tobacco protoplasts. When the protoplasts were lysed with Triton X-100, full-length minus strands were present in the cytoplasmic but not in the nuclear fraction. With mechanically broken protoplasts, the crude nuclear fraction (250 g pellet) contained small amount of minus strands which appeared to derive from unbroken protoplasts, but most of minus strands were recovered in a fraction sedimented between 250 and 2500 g, little if any being found in lighter fractions. The results indicate that TMV-RNA replicates in association with an extranuclear structure.

Blotting, Northern↗
PubMed1988

Buoyant sustained release tablets based on chitosan.

This study attempted to develop sustained release intragastric 'floating' tablets based on chitosan. Two kinds of chitosan with different degrees of deacetylation (chitosan H and L) were used, and two types of preparations (types A and B) were examined. Type A preparations, i.e. directly compressed tablets using a mixture of sodium hydrogen carbonate and citric acid, were buoyant immediately and gave sustained release of prednisolone (as model drug) in acidic dissolution fluid. Type B preparations, i.e. preparations composed of a directly compressed layer and a chitosan H membrane layer enclosing carbon dioxide (a foamy membrane layer), quickly developed buoyancy and also provided sustained release of drug. The drug release rate from the preparation using chitosan L was slower than that from the preparation using chitosan H. In an absorption study using beagle dogs, sustained drug absorption from Type B preparations was obtained.

Animals↗
PubMed1988

Effect of cyclohexanone derivatives on percutaneous absorption of ketoprofen and indomethacin.

The promoting effect of cyclohexanone derivatives on the percutaneous absorption of ketoprofen and indomethacin from gel ointments was investigated in rats. Drug absorption was markedly enhanced by the addition of 2-tert-butylcyclohexanone. Promoting activities of 2,6-dimethyl and 4-tert-butylcyclohexanone were also observed, but their effects were significantly lower than that of the 2-tert-butyl derivative. The effect of side chain length at the 2-position of the cyclohexanone ring on the percutaneous absorption of these drugs was determined similarly using a series of 2-n-alkylcyclohexanones. Pronounced effects were observed in the case of 2-n-octylcyclohexanone, suggesting that a chain length of eight carbons is an important factor for absorption enhancement in this series. The extent of absorption enhancement was found to be an almost linear function of 2-n-octycyclohexanone concentrations in the range from 0 to 10%.

Administration, Cutaneous↗
PubMed1988

Preparation and evaluation of bovine serum albumin nanospheres coated with monoclonal antibodies.

Bovine serum albumin nanospheres (BSA-NS), prepared with glutaraldehyde cross-linking and ultrasonication, were coated with antibodies by covalent linkage (Schiff's base formation) of aldehyde groups at the surface of the nanospheres with amino groups of the antibody. The coating was confirmed using Fluorescein isothiocyanate which conjugates with antibodies and also by the antigen-antibody interaction using Sepharose beads. Rapid in vitro degradation of BSA-NS was first confirmed by incubating a radioactive nanosphere suspension at 37 degrees C in 0.25 M sucrose solution with 1% liver or lung extract. The radioactive compound conjugated BSA-NS suspension was then administered to mice intravenously, and tissue distribution of BSA-NS was examined using whole body autoradiography; the BSA-NS were found to be localized mainly in the liver, the lungs and the kidneys and 4 hr and 24 hr after injection, almost all radioactivity had disappeared except for that in the kidneys. The binding ratio of monoclonal antibodies to tumor cells in vitro was found to be 2-2.5 times greater than that of control antibodies (mouse IgG) by means of a gamma ray counter. An in vivo binding test showed that monoclonal antibodies might recognize the target organ (Lewis lung carcinoma). Applying these findings, BSA-NS coated with monoclonal antibodies were found to be trapped in the tumoral tissue of Lewis lung carcinoma-bearing mice more than in controls (BSA-NS coated with mouse IgG) at 24 hr after the injection. Thus, BSA-NS offer potential as useful drug carriers enabling concentration of drugs at specific target sites. Furthermore, their rapid elimination from the body and their degradability suggest that side effects due to long-lasting accumulation in several organs may be avoided.

Animals↗
PubMed1987

Base substitutions in transposable element IS1 cause DNA duplication of variable length at the target site for plasmid co-integration.

We demonstrate that base substitutions in the IS1 sequence affect the length of the nucleotide sequence which is duplicated during IS1-mediated co-integration. IS1K, an IS1 variant present in the Escherichia coli chromosome, has seven base substitutions in its sequence as compared with that of IS1R derived from the plasmid R100. All substitutions are located in the internal region of IS1K. We have constructed plasmids containing IS1R, IS1K and hybrids between them: one contains four base substitutions causing an amino acid substitution in the insA gene and the other has three substitutions producing an amino acid substitution in the insB gene. We have isolated co-integrate plasmids formed by each IS1 and analysed nucleotide sequences of the target sites duplicated at the co-integration junctions. The results show that IS1K generates duplications of 8 or 14 bp as well as 9 bp, while IS1R exclusively generates the 9-bp duplications. Both hybrid IS1s also create 8- or 7-bp target duplications in addition to 9-bp duplications. These results indicate that the base substitutions in either insA or insB are sufficient for the occurrence of unusual target duplications, suggesting that both genes are involved in the target duplication.

Base Sequence↗
PubMed1987

Enhancement of the oral bioavailability of cinnarizine in oleic acid in beagle dogs.

The present study was an attempt to develop a new dosage form of cinnarizine, which is slightly soluble in water, using lipid as a vehicle. The solubility of cinnarizine in several organic solvents was determined. It was found that cinnarizine dissolved well in oleic and linoleic acids. The bioavailability of cinnarizine from the oral administration of an oleic acid solution in a hard capsule was investigated and compared with that of a cinnarizine tablet, using beagle dogs. When cinnarizine was administered in a capsule, the bioavailability was greatly enhanced [i.e., the maximum concentration (Cmax) and AUC values were 2.9 and 4.0 times larger than those of a cinnarizine tablet, respectively]. Meanwhile, the tmax value (the time to reach Cmax) was unchanged. The absorption of cinnarizine from an oleic acid solution was considered to depend on the action of bile salts. This was supported by the results of a dissolution test using a bile salts solution as the dissolution test medium.

Animals↗
PubMed1987

The promoter proximal region in the virD locus of Agrobacterium tumefaciens is necessary for the plant-inducible circularization of T-DNA.

The formation of crown gall tumours involves the transfer of the T-DNA region of the Ti plasmid from Agrobacterium to plant cells and its subsequent integration into plant chromosomes. When agrobacteria are incubated with plant protoplasts or exudates of plants, the T-DNA region is circularized by recombination or cleavage and rejoining between the 25 bp terminal repeats; the formation of circular T-DNAs is thought to be one step in T-DNA transfer (Koukolikova-Nicola et al. 1985; Machida et al. 1986). We previously showed that the virulence region of the Ti plasmid is required for T-DNA circularization. In the present paper, we examined the circularization event in agrobacteria harbouring octopine Ti plasmids with mutations in various loci of the virulence region. The results clearly demonstrate that the gene(s) encoded in the virD locus are necessary for T-DNA circularization. In particular, the gene(s) present in the region proximal to the virD promoter are essential. We propose that product(s) of this gene have recombinase or endonuclease activity which specifically recognizes the 25 bp terminal repeats of T-DNA.

DNA, Bacterial↗