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Biomedical subjects

J Mizoguchi

Publications and source records attributed to J Mizoguchi.

30 records · Page 2Linked to original sources
PubMed1985

Efficient expression in Escherichia coli of two species of human interferon-alpha and their hybrid molecules.

A new type of interferon (IFN)-alpha cDNA (IFN-alpha I') was identified in a cDNA library constructed from Namalva cells infected with Sendai virus. The nucleotide sequence of this cDNA showed homology, with the exception of two nucleotides in the coding region, with the previously identified IFN-alpha I gene (Lawn et al., 1981). An expression plasmid which directs the synthesis of the mature IFN-alpha I' peptide was constructed using vectors carrying the lpp/lac promoter and "runaway" replicon. Furthermore, hybrid genes were constructed by in vitro recombination of IFN-alpha I' and IFN-alpha A at a common restriction endonuclease site located at amino acid positions 121-122. While the specific antiviral and anticellular activities of IFN alpha A and IFN-alpha I' on human cells were comparable, the antiviral activity of IFN-alpha I' on mouse cells was 125-fold higher than that of IFN-alpha A. The specific antiviral activities of the hybrid IFNs on human and bovine cells were similar to that of the amino-terminal parental IFN peptide, while the anticellular activities on human cells of the alpha A/alpha I' hybrid were higher and that of the alpha I'/alpha A hybrid were lower than the parental IFN-alpha A and IFN-alpha I'.

Amino Acid Sequence↗
PubMed1985

[Simplification of the intravenous glucose tolerance test (ivGTT) in rats].

A simplified technique was established for the intravenous glucose tolerance test (ivGTT) in unanesthetized rats. In order to evaluate the relation between insulin secretion, glucose load and glucose disappearance rate, precatheterized rats were given glucose ranging in dose from 0.25 to 2.0 g/kg bw by intravenous injection. A highly linear correlation was observed in glucose disappearance rate during a period of 4-32 min. A glucose load greater than 0.5 g/kg ow induced a maximum response in insulin secretion. Small blood samples were collected using the orbital bleeding technique at 4, 16 and 28 minutes after a glucose load of 1.0 g/kg bw had been given and then T1/2, the time taken for the glucose level to fall by one half, was calculated. The mean T1/2 was significantly longer in alloxan- or cyproheptadin-diabetic rats than that in the intacts. These data indicate that a glucose load of 1.0 g/kg administered by intravenous injection with the T1/2 calculated between 4 and 32 minutes would provide an accurate means of assessing pancreatic endocrine function.

Animals↗
PubMed1980

On the process of cellular division in Escherichia coli: isolation and characterization of penicillin-binding proteins 1a, 1b, and 3.

Multiple mutants of Escherichia coli defective in penicillin-binding proteins (PBPs) were constructed, and into these strains Co1E1 plasmids carrying the genes for PBP-1a, -1b, or -3 were introduced. From these plasmid-carrying strains, PBP-1a and -1b were purified by ampicillin-Sepharose affinity chromatography and PBP-3 by cephalexin-Sepharose affinity chromatography. Improved purification was achieved by differential elution with NH2OH. Purified PBP-1b synthesized murein when added to the membrane fraction of a PBP-1b-defective mutant, which by itself failed to support murein synthesis in vitro. The PBP-1b preparation was able to synthesize murein from the lipid intermediate extracted with chloroform/methanol but was unable to utilize UDP-linked precursors for murein synthesis. Murein synthesis was inhibited by vancomysin, ristocetin, moenomycin, and enduracidin, but not by beta-lactam antibiotics. The synthesized murein was shown to contain crosslinked muropeptides. Their crosslinking was abolished by action of beta-lactam antibiotics. The PBP-1a and -3 preparations showed substantially no activity for murein synthesis in the same reaction system. None of the three PBPs showed D-alanine carboxypeptidase activity with UDP-N-acetylmuramoyl-pentapeptide as substrate or endopeptidase activity with bis(disaccharide-peptide) as substrate.

Bacterial Proteins↗
PubMed1980

Double-replica topography of disk membrane structures in the carp (Cyprinus carpio).

By an improved freeze-fracture device, a number of double replicas were obtained from the rod disk membranes of the carp retina for investigation of complementary, continuing, and transitional relationships between fracture faces. Some separate particles found along the smooth edge bordering on the adjacent interdisk cytoplasm can be occasionally matched with gaps found between particles forming the complementary rough face edge. Consequently the particles on both faces can be derived from a single continuous layer, corresponding to the ad-cytoplasmic component of the disk membrane. This observation seems to agree with a prevailing disk-membrane model in which the visual pigment molecules are localized in the ad-cytoplasmic lipid lamella, but not to conform with a recent hypothesis, based upon single replicas, that the fracture plane might pass along either the inner or outer true surface of the membrane and the visual pigment molecules be attached to the latter.

Animals↗
PubMed1980

Complementary freeze fracture methods applied to cattle disk membranes.

The rod-outer-segment disk membranes were studied in cattle retinas by electron microscope observation of ultrathin resin sections and complementary freeze replicas. In sections, the membranes are characterized by discontinuous electron densities along the unit membrane structure, in which electron-less-dense globular substructures, forming an intermediate layer, are enhanced. Such substructures are estimated as 60 A in diameter. In freeze replicas, the membranous particles of 77 A in diameter are distributed quite densely in the P-face and scattered in the E-face. Like a number of preceding investigators who have failed to obtain convincing findings to correlate similar profiles with the visual pigment molecules, we should also raise a question about preparation involving chemical and thermal procedures affecting the dimensions of the final images. Our constant results obtained from the two methods, however, will suggest that the thin-section substructures and freeze-replica particles represent two different phases respectively of the same molecular existence rather than a complete profile of the visual pigment. It is also uncertain yet whether one membranous particle should be in fact associated to one molecular pigment or an aggregation of several molecules. The last problem will be resolved to some extent by topographical analyses of the complementary replicas in progress in our laboratory.

Animals↗
PubMed1980

Effect of a combination of benzylpenicillin or ampicillin and dicloxacillin on peptidoglycan synthesis in a cell-free enzyme system from a beta-lactamase producing strain of Citrobacter freundii.

The membrane fraction prepared from beta-lactamase producing Citrobacter freundii GN346 catalyzed in vitro peptidoglycan synthesis from uridine-5'-diphosphate-N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelyl- D-alanyl-D-alanine and uridine-5'-diphosphate-N-acetylglucosamine, which was accompanied by the release of alanine from the carboxyl terminal end of the former substrate. Though this reaction was inhibited by benzylpenicillin (PCG) and ampicillin (ABPC), the reaction was relatively insensitive compared with that catalyzed by the membrane fraction from a derived beta-lactamaseless mutant strain GN346/16. In contrast, the enzyme activity of the parent strain was strongly inhibited by a combination of PCG or ABPC and dicloxacillin (MDIPC). The beta-lactamase present in the membrane fraction from the parent strain showed stronger activity than that from the mutant strain, and the activity was inhibited by MDIPC as in the case of the soluble enzyme localized in the periplasmic space.

Ampicillin↗
PubMed1979

Mechanism of synergistic action of a combination of ampicillin and dicloxacillin against a beta-lactamase-producing strain of Citrobacter freundii.

The mechanism of synergistic activity of a combination of ampicillin and dicloxacillin was studied on beta-lactamase-producing Citrobacter freundii GN346 and its derived beta-lactamaseless mutant GN346/16. The synergistic activity was exhibited against the parent strain but not against the mutant strain. Precultivation of the parent strain with the combination reduced the amount of the subsequent binding of [14C]penicillin G to the membrane fraction from the treated cells, but no reduction was observed in the case of cells treated with ampicillin or dicloxacillin alone. On the other hand, the amount of binding of [14C]penicillin G to the membrane fraction from the mutant strain was reduced by ampicillin treatment alone. These results clearly indicated that dicloxacillin inhibited the beta-lactamase activity produced by the parent strain, and, consequently, ampicillin can penetrate through the outer membrane and periplasmic beta-lactamase barrier into its target sites on the cytoplasmic membrane.

Ampicillin↗
PubMed1978

[Synergistic effect of ampicillin and dicloxacillin on penicillin and cephalosporin-susceptible Escherichia coli (author's transl)].

An effect of a combination of ampicillin (ABPC) and dicloxacillin (MDIPC) on penicillins and cephalosporin-susceptible E. coli was determined. Minimum inhibitory concentrations of the combined drug were as same as that of ABPC, but bacterial growth was inhibited by the combined drug stronger than ABPC, low activity of beta-lactamase was detected in sonicated E. coli 0.225 cells, and this activity was inhibited by relatively low concentration of MDIPC. We considered that a weak synergism of the combined drug might attribute to the inhibition of the beta-lactamase activity by MDIPC.

Ampicillin↗
PubMed1977

On the mode of action of a new antifungal antibiotic, aculeacin A: inhibition of cell wall synthesis in Saccharomyces cerevisiae.

The mode of action of a new antifungal antibiotic, aculeacin A, was studied with the cells of Saccharomyces cerevisiae. In the presence of aculeacin A, the distinct decrease of viable cells was observed. The most of cells treated with aculeacin A lysed with releasing intracellular substances at the tips of their buds. This lysis was considered to be due to the inhibition of cell wall synthesis, because the incorporation of glucose into the cell wall glucan was significantly reduced. Aculeacin A also had a weak activity to burst the protoplasts of S. cerevisiae at a relatively high concentration.

Antifungal Agents↗