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Biomedical subjects

S Ihara

Publications and source records attributed to S Ihara.

At least 109 records · Page 6Linked to original sources
PubMed1985

Energy difference associated with proline isomerization in ribonuclease A.

We examined energy differences caused by the cis-trans transformation of every proline residues in the native structure of RNAase A. The results show that the cis form of Pro-93 and Pro-114 gave the lowest conformational energy, i.e., conformations after conversion of one of the proline residues to the trans form had a little higher energy; the transformation of Pro-42 and Pro-117 to the cis form, on the other hand, caused a much higher energy increase.

Isomerism↗
PubMed1985

The expression of viral functions is necessary for recombination of a herpesvirus (pseudorabies).

To determine whether viral functions are necessary for recombination of the pseudorabies virus genome in infected cells, we have used as a model system marker rescue at the permissive temperature (PT) and nonpermissive temperature (NPT) of a temperature sensitive mutant (tsG1) deficient in the immediate-early (180K) protein. Two restriction fragments, both of which can rescue tsG1 at the PT but only one of which encompasses the whole immediate-early gene and can complement tsG1, were compared for their ability to rescue the mutant at the NPT. Although both restriction fragments rescued the mutant with equal frequency at the PT, only the fragment which could express the immediate-early 180K protein prior to recombination, i.e. could complement tsG1, rescued the mutant at the NPT. We conclude that the expression of viral functions is necessary for high frequency recombination of the pseudorabies virus genome.

Animals↗
PubMed1984

Preparation and characterization of antibodies to O-phosphotyrosine and their use for identification of phosphotyrosine-containing proteins.

To facilitate the identification of phosphotyrosine (P-tyr)-containing proteins, rabbit polyclonal antibodies and mouse monoclonal antibody specifically reactive to P-tyr were prepared by hyperimmunizing the animals with P-tyr-conjugated bovine serum albumin or poly-L-lysine. As determined by a solid-phase radioimmunoassay and an enzyme-linked immunosorbent assay, the antibodies reacted with P-tyr-conjugated target antigens but not with those conjugated with phosphoserine (P-ser) or phosphothreonine (P-thr). This immune reaction was strongly blocked by 2 mM P-tyr and phenylphosphate but not by P-ser or P-thr. The antibodies were capable of isolating, as the major P-tyr-containing components, a 170kd protein (most likely the EGF receptor) from EGF-stimulated, 32P-labelled A431 cells, and 130kd and 60kd proteins from Rous sarcoma virus (RSV)-transformed chick cell lysate which had been labelled in vitro with gamma-32P-ATP. Immunofluorescent staining of RSV-transformed cells and A431 cells showed specific localization of P-tyr-containing proteins in the cytoplasm, plasma membrane, and nucleolus-like structures. The results demonstrated the usefulness of the antibodies for identification or isolation of P-tyr-containing proteins.

Animals↗
PubMed1984

A group of bactericidal factors conserved by vertebrates for more than 300 million years.

A complement-dependent bactericidal factor (RaRF) specific for the Ra chemotype strains of Salmonella and for the Ra-like strains of other enterobacteria has been found in sera of mice. We show here that the anti-Ra bactericidal factors are present in sera of all species, so far tested, of mammals, birds, reptiles, amphibians, and bony and cartilaginous fish. Certain properties, such as binding specificity, requirement of divalent cations for binding, and sensitivities to heat and reducing agents, of the factor in the representative animals were the same as or similar to those of the mouse RaRF. These results indicate that these factors have been conserved by vertebrates for more than 300 million years as a result of the necessity for the resistance to rough mutants of Gram-negative bacteria.

Amphibians↗
PubMed1983

Localization of the regions of homology between the genomes of herpes simplex virus, type 1, and pseudorabies virus.

Only 8% of the sequences of the genomes of pseudorabies (PRV) and herpes simplex (type 1) (HSV) viruses are homologous. These homologous sequences have been shown previously to be distributed throughout most of the genomes of the two viruses. By means of blot hybridization of restriction fragments of HSV-1 DNA to cloned, nick-translated restriction fragments of PRV DNA, it was possible to compare the location on the genomes of these viruses of the homologous regions. The results showed that the genome of PRV is, for the most part, colinear with the IL arrangement of the genome of HSV-1. An inversion or translocation of sequences mapping on the PRV genome between 0.07 and 0.39 map units was observed on the genome of one of these viruses. A comparison of the map positions of five genes with known functions confirmed these findings. The genes coding for the major immediate-early protein, the major capsid protein, and the thymidine kinase occupy similar positions on the genome of PRV and on the genome of HSV-1 in the IL arrangement. However, the genes for DNA polymerase and for the major DNA binding protein appear to be inverted relative to one another on the genomes of the two viruses.

Base Sequence↗
PubMed1983

Characterization of the immediate-early functions of pseudorabies virus.

The immediate-early transcripts of pseudorabies virus have been located in a region of the genome situated internally within the inverted repeat between map positions 0.99 and 0.95. A single immediate-early transcript (approximately 6 kb) can be detected both in the cytoplasmic and nuclear fractions of infected, cycloheximide-treated cells. Analysis of the proteins synthesized after removal of cycloheximide from infected cells or after translation in vitro of the RNA isolated from these cells revealed the presence of a single protein (180K) not present in similarly treated, uninfected cells. That this is a virus protein and is specified by the immediate-early region of the genome was shown by selection and translation of mRNA hybridizing with virus DNA from the appropriate region of the genome. The effects of infection of cells with a temperature-sensitive mutant (tsG1) defective in the 180K protein were studied. At the nonpermissive temperature only immediate-early RNA was transcribed and only one virus protein, the 180K protein was synthesized. Inhibition of cellular protein and DNA synthesis was also observed. After shift down of tsG1-infected cells from the nonpermissive to the permissive temperature at 3 hr post infection, a transition to early RNA transcription occurred. However, if the shift down was delayed until 5 hr post infection, transcription of the virus genome was completely inhibited and an abortive infection ensued. Shift of the mutant-infected cells from the permissive to the nonpermissive temperature resulted in a decrease in the rate of accumulation of early and late transcripts, and a resumption of the synthesis of immediate-early RNA and protein. From these as well as from previous results, it is concluded that pseudorabies virus codes for a single multifunctional immediate-early protein which is essential for the transcription of immediate-early to early RNA and is required for the continuous transcription of early (and late) RNA. The immediate-early protein is also self-regulatory; the presence of the functional immediate-early protein represses the transcription of its RNA. In addition, the immediate-early protein of pseudorabies virus appears to play a direct role, under certain conditions, in the inhibition of cellular macromolecular synthesis.

Chromosome Mapping↗
PubMed1982

Suppression of fibronectin synthesis by an early function(s) of human cytomegalovirus.

Labelling of fibronectin with [3H]leucine and its isolation by immunoprecipitation followed by electrophoresis on gels showed that fibronectin synthesis was specifically suppressed in human embryonic cells infected with human cytomegalovirus. Degradation or release of pre-existing fibronectin into the medium was not affected. The inhibition of fibronectin synthesis was also observed when cells were infected with a DNA-minus temperature-sensitive mutant at the non-permissive temperature but not observed in infection with u.v. -irradiated virus, suggesting the involvement of the expression of an early virus function(s). This capacity of the virus may be implicated in the virus-induced early cell rounding.

Cell Line↗
PubMed1982

A new complement-dependent bactericidal factor found in nonimmune mouse sera: specific binding to polysaccharide of Ra chemotype Salmonella.

It has been shown that nonimmune mouse sera contain a complement-dependent bactericidal factor that reacts specifically with Ra chemotype Salmonella. In this study we investigate a specific determinant to which this factor binds. This factor bound to Ra chemotype lipopolysaccharide (LPS) but not to S or Re chemotype LPS. The binding was markedly inhibited by N-acetyl-D-glucosamine (GlcNAc), which was the nonreducing terminal of the Ra polysaccharide chain and by certain monosaccharides structurally relating to L-glycero-D-mannoheptose, a terminal component of a side branch of Ra polysaccharide. The factor bound to the Ra bacteria could be eluted with a medium containing GlcNAc. These results indicate that the specific determinant is the polysaccharide region of LPS characteristic of Ra chemotype Salmonella. Ca2+ but not Mg2+ was required for the specific binding of the factor to cells of Ra bacteria. A molecule composed of a polypeptide of 28,000 m.w. was found in the active fraction obtained by the monosaccharide elution. However, no polypeptides corresponding to light and heavy chains of mouse immunoglobins were detected from the active fraction.

Acetylglucosamine↗
PubMed1982

[Pathogenetic study of complete and partial hydatidiform mole by HLA (author's transl)].

Twenty four complete and 15 partial moles, and the lymphocytes from the parents were analyzed for human lymphocyte antigen (HLA-A and HLA-B specificities), and karyotyping was done in each molar tissue by the direct method. Twelve of the 24 complete moles expressed homozygous A and/or B specificities identical to those of the father. No cases expressed A or B specificities derived from the maternal side. All had a 46, XX karyotype. On the other hand, in 6 of the 15 partial moles, the antigen specificities were heterozygous for A locus and 10 of the 15 expressed A and/or B specificities derived selectively from the maternal side. In chromosome studies, 8 of the 15 had a 69,XX karyotype, 5 had a 46,XX karyotype and 2 was impossible of analysis. These results show that complete moles are mostly androgenetic in origin but partial moles are not; that is, pathogenesis distinguishes complete from partial moles.

Adult↗
PubMed1980

Effects of oral befunolol on heart rate and systolic blood pressure during submaximal exercise in man.

For the purpose of determining exercise intensity required for evaluating the effect of beta-blocking agents, the multi-stage treadmill exercise was carried out up to intensity of 85% of maximal oxygen intake (VO2max) after administration of beta-blocking agents in 7 healthy men. To obtain a stable dose response in the inhibitory effect of beta-blocking agents on heart rate (HR) and systolic blood pressure (S-BP), the exercise intensity more than 65% of VO2max (75% of maximal heart rate) was needed. In order to evaluate the effect of befunolol (BFE), a submaximal treadmill exercise of 75% of the age adjusted predicted maximal heart rate was loaded in 6 healthy men at 1.5, 4, and 8 hours following a single oral administration of 10 mg, 20 mg or 40 mg of BFE and 20 mg or 40 mg of propranolol. Simultaneously, the plasma concentration of BFE was determined 1.5, 4, 6 and 8 hours after the administration of BFE at each dose. In human serum, BFE was detected together with its metabolite, revealing a significant correlation between BFE and metabolite (r = 0.94, p < 0.001). Almost a certain rate of metabolite (4--5 times) was detected against BFE. As for the biological half life, it was 1.79 +/- 0.13 hours with BFE and 3.67 +/- 1.33 hours with metabolite. The inhibitory effect of BFE on HR and S-BP during exercise exhibited a dose response with the oral dose and its plasma concentration, and was almost twice as much as that of propranolol at the same dose. Accordingly, the myocardial oxygen consumption which may be represented as rate pressure product was inhibited twice as much as propranolol. BFE is characteristic of its more rapid elimination of its effect compared to the other beta-blocking agents. The decrease in the inhibitory effect of BFE or HR during exercise was about 1.8 times quicker than that of propranolol.

Administration, Oral↗
PubMed1980

Human cytomegalovirus-induced inhibition of exogenous thymidine uptake into cell DNA in HEL cells stimulated to proliferate with serum.

In contrast with the previous findings by us and others, human cytomegalovirus (HCMV) infection caused inhibition of exogenous 3H-dThd uptake into cell DNA in human embryonic lung (HEL) cells which were stimulated to proliferate with serum at the time of infection. The response of HEL cells to HCMV infection varied depending on the HEL cell population, and the inhibition of 3H-dThd incorporation was observed in a particular HEL cell population prepared in our laboratory. That the inhibition was caused by HCMV virion was shown by: (i) antiserum against HCMV prevented the virus inoculum from inhibiting 3H-dThd uptake, and (ii) removal of virions from an infecting virus stock by centrifugation resulted in no inhibition. The virus-induced inhibition was enhanced by uv-irradiation of infecting virus, suggesting that the expression of viral gene functions was not necessarily required for the inhibition. comparison between autoradiography of 3H-dThd-labeled infected cells and the total amounts of 3H incorporated into DNA indicated that HCMV reduced the overall rate of 3H incorporation into DNA in infected cells and the number of cells entering the S phase of the cell cycle.

Blood↗