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Biomedical subjects

R Itoh

Publications and source records attributed to R Itoh.

At least 181 records · Page 10Linked to original sources
PubMed1989

Influence of pyrazine derivatives on the day of vaginal opening in juvenile female rats.

Effects of pyrazine derivatives on the day of the first opening of the vagina in juvenile female rats were studied. Tetraethyl and 2,5-dimethyl pyrazine caused a significant delay in the first vaginal opening day of juvenile female rats, but no delay was noted in the case of 2,5-diethyl or triethyl pyrazine. These results suggest that tetraethyl and 2,5-dimethyl pyrazine cause delays in the onset of puberty in juvenile female rats.

Animals↗
PubMed1989

Sex as a factor in levels of serum ascorbic acid in a healthy elderly population.

To investigate gender difference in serum ascorbic acid levels in healthy elderly, its status was studied in 175 free-living and healthy elderly people aged 63-81, who were not using ascorbic acid supplement. Both mean dietary ascorbic acid intake (3.2 +/- 1.3 mg/kg of body weight/day) and its serum concentration (1.11 +/- 0.23 mg/100 ml) for females (n = 96) were significantly higher than for males (2.7 +/- 1.1 mg/kg/day and 0.91 +/- 0.30 mg/100 ml; n = 79). It was estimated that intakes needed to maintain a serum ascorbic acid concentration of 1.0 mg/100 ml would be about 2 mg/kg of body weight/day for females and about 3 mg/kg/day for males. In this population, dietary ascorbic acid intake was the most important predictor of its serum concentration, but sex was also significantly related to it, accounting about 7% of its total variation.

Aged↗
PubMed1989

Adenosine and dopamine simultaneously determined in urine by reversed-phase HPLC, with on-line measurement of ultraviolet absorbance and electrochemical detection.

This assay method allows the simultaneous determination of adenosine and dopamine in 0.5 mL of human urine within approximately 35 min, by using isocratic, reversed-phase, high-performance liquid chromatography coupled with an on-line detector for ultraviolet absorbance and electrochemical activity. The analytes were rapidly separated on an affinity column packed with phenylboronate-bonded silica. Mean recoveries for adenosine, 2-chloroadenosine (internal standard), dopamine, and (+/-)-isoproterenol (also an internal standard) were 91%, 99%, 88%, and 104%, respectively. The calibration curves for adenosine and dopamine were linear (r = 0.999, P less than 0.01) over the respective concentration ranges of 0.10 to 2.00 mg/L and 0.05 to 1.00 mg/L. Analytical precisions, assessed by the within-day and the day-to-day CVs, were 4.5% and 6.5% for adenosine, and 5.1% and 6.6% for dopamine, respectively. The mean (+/- SD) concentrations of adenosine (1.27 +/- 0.73 mg/L) and dopamine concentrations (0.38 +/- 0.25 mg/L) measured in urine from 19 healthy subjects agreed well with those previously reported.

2-Chloroadenosine↗
PubMed1988

DNA distribution pattern of the so-called severe dysplasias and small carcinomas of the colon and rectum and its possible significance in the tumor progression.

The DNA distribution pattern was determined by cytofluorometry in 25 cases of colorectal small carcinoma and the so-called severe dysplasia. The colorectal carcinoma and "severe dysplasia" consisted of four principal stemlines as to DNA ploidy: diploidy, aneuploidy, and their respective polyploidies. These patterns appeared in various combinations in individual neoplasms. DNA distribution of the severe dysplasia was diploid-predominant (11 cases) or aneuploid-predominant (three cases), usually showing mosaicism in various degrees with respective first order polyploidy. Similar DNA distribution patterns also were found in submucosally invasive small carcinomas. The neoplastic cell populations of a higher polyploidy (second or third order), however, occurred only in the submucosally invasive carcinomas (three cases) regardless of their basic ploidy. The mitotic index tended to be higher in the aneuploid-predominant tumors than in the diploid-predominant tumors. In the current observation, there was no significant correlation between the DNA distribution pattern and histologic type of the "dysplasia" or carcinoma. We found that most of the so-called severe dysplasias of the colon and rectum already gained definitive characteristic of carcinoma in the DNA pattern, i.e., ploidy heterogeneity. Therefore, they can be identified as intramucosal carcinomas, distinct from the normal epithelia and adenomas of the colon and rectum.

Aneuploidy↗
PubMed1988

A reappraisal of the subunit molecular mass of chicken liver cytosol 5'-nucleotidase.

The subunit molecular mass of chicken liver cytosol 5'-nucleotidase was earlier reported to be 51 kDa upon sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (Naito, Y. and Tsushima, K. (1976) Biochim. Biophys. Acta 438, 159-168). By immunoblot analyses after SDS-gel electrophoresis, however, a fraction from the liver homogenized in the presence of leupeptin showed multiple bands with molecular masses around 57 kDa, and SDS-extracted proteins directly from the liver exhibited a single 70 kDa component. These results indicate that the 51 kDa peptide observed in the cytosol 5'-nucleotidase preparation might, in fact, be a proteolytic artifact.

5'-Nucleotidase↗
PubMed1988

Immunocytochemical localization of cytosol 5'-nucleotidase in chicken liver.

We investigated the localization of cytosol 5'-nucleotidase in chicken liver by use of a pre-embedding immunoenzyme technique. Cytosol 5'-nucleotidase was purified from chicken liver and a monospecific antibody to this enzyme was raised in a rabbit. Fab fragments of the antibody were conjugated with horseradish peroxidase. Tissue sections of the fixed chicken liver were incubated with the peroxidase-Fab fragments, followed by DAB reaction for peroxidase. By light microscopy, dark-brown staining was present in the cytoplasm of parenchymal cells, Kupffer cells, and endothelial cells. The latter two types of cells were stained more strongly than the former. By electron microscopy, reaction deposits were present in the cytoplasmic matrix but not in cell organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes, or in nuclei. In control sections incubated with peroxidase-conjugated Fab fragments from non-immunized rabbit, no specific reaction was noted. The results indicate that cytosol 5'-nucleotidase is contained more in the sinus-lining cells and less in the parenchymal cells, and that the enzyme is present in the cytoplasmic matrix of these cells.

5'-Nucleotidase↗
PubMed1988

The bialaphos resistance gene (bar) plays a role in both self-defense and bialaphos biosynthesis in Streptomyces hygroscopicus.

We inactivated the bialaphos (BA) resistance gene (bar) of a BA producer, Streptomyces hygroscopicus, by the gene replacement technique. The resulting BA-sensitive mutant (Bar-) was able to produce little BA but considerable amount of an intermediate demethylphosphinothricin (DMPT). The Bar- mutant was still able to convert the N-acetyl derivative (AcDMPT) of DMPT to BA. Introduction of normal bar containing plasmid restored both BA resistance and BA biosynthesis to levels as high as the parental BA producer. By contrast, introducing a multi copy glutamine synthetase gene (glnA) into the Bar- mutant restored BA resistance but not BA production. Thus, the bar gene plays a crucial role in both self-defense and a step of BA biosynthesis in the BA-producing S. hygroscopicus.

Anti-Bacterial Agents↗
PubMed1988

Replacement of Streptomyces hygroscopicus genomic segments with in vitro altered DNA sequences.

We have developed a method for gene replacement in Streptomyces hygroscopicus which permits introduction of an in vitro derived mutation carried on a plasmid into the chromosome. We constructed the plasmid pMSB212 which can replicate in S. hygroscopicus and contains the step5 gene of the bialaphos biosynthetic pathway which was inactivated by a frame-shift mutation caused by filling in the cohesive ends of the EcoR I site in the structural gene. pMSB212 was introduced into a bialaphos producer strain and by protoplast regeneration of the primary thiostrepton-resistant transformants, non-producing mutants, were obtained. Biochemical and genetical analyses indicated that these mutants were specifically blocked by introduction of the frame-shift mutation in the step5 gene on the chromosome. This method will enable us to obtain isogenic mutants of known genes and to identify new genes encoded on a cloned fragment.

Chromosomes, Bacterial↗
PubMed1988

The bialaphos biosynthetic genes of Streptomyces hygroscopicus: cloning and analysis of the genes involved in the alanylation step.

We have isolated and studied the genes involved in the alanylation step in the biosynthesis of a herbicide, bialaphos which is produced by Streptomyces hygroscopicus. Three bialaphos-nonproducing mutants, NP60, NP61 and NP62, isolated from S. hygroscopicus by treatment with N-methyl-N'-nitro-N-nitrosoguanidine were defective for the alanylation step and were not restored to productivity by any locus of the gene cluster previously cloned. Three plasmids were isolated using NP60, NP61 and NP62 as recipients. The genes which restored productivity to NP61 and NP62 hybridized to the contiguous region of the bialaphos biosynthetic gene cluster. The gene cluster involved in the bialaphos production was about 35 kb long. The gene which restored productivity to NP60 did not hybridize to the bialaphos biosynthetic gene cluster. VM3 and VM4, putative alanylation blocked mutants, were derived from a bialaphos producer by gene replacement of an unidentified region of the biosynthetic gene cluster with an in vitro altered DNA sequence. The genes which restored productivity to VM3 and VM4 were located between the genes which code for phosphinomethylmalic acid synthase and demethylphosphinothricin acetyltransferase in the cluster. These results suggest that multiple genes are involved in the alanylation step.

Alanine↗
PubMed1987

Characteristics of colorectal epithelia and adenomas as revealed by DNA cytofluorometry.

Human colorectal normal epithelia and tubular adenomas were studied by DNA-cytofluorometry using free cell nuclei isolated from formalin-fixed and paraffin-embedded specimens. All the normal epithelia (30 cases) showed low proliferative activity, no polyploid cells and no aneuploid cell clones at any age in either sex. The mean diploid G1/G0 fraction (DF) of the normal epithelia was 95.9%. The adenomas, on the other hand, showed increased proliferative activity usually in accordance with the grade of atypia. The mean DF values of the adenomas with mild atypia (31 lesions) and moderate atypia (21 lesions) were 89.4% and 85.6%, respectively. The adenomas, irrespective of their grade of atypia, occasionally showed low proliferative activity, while in the adenomas adjacent to a carcinoma, the proliferative activity was relatively high even though their atypia was mild. Neither polyploid cells nor aneuploid cell clones were found in the adenomas. Therefore, polyploid and aneuploid cell populations are characteristics of carcinoma of the colon and rectum, and this criterion should be useful in investigations of the genesis of carcinoma in the human colorectal mucosa.

Adenoma↗
PubMed1986

Regulation of rat heart cytosol 5'-nucleotidase by adenylate energy charge.

A 5'-nucleotidase (EC 3.1.3.5) was highly purified from the soluble fraction of rat heart. The preparation appeared homogeneous by the criterion of polyacrylamide-gel electrophoresis. The enzyme was activated by ATP and ADP, and inhibited by Pi. When AMP was used as substrate, the velocity/substrate-concentration plot was sigmoidal. ATP or ADP changed the plot to hyperbolic and decreased S0.5. Pi increased both the sigmoidicity of the plot and S0.5. When IMP was used as substrate, the velocity/substrate plot was hyperbolic. ATP or ADP decreased Km and increased V. Pi changed the plot to sigmoidal and increased S0.5. Within the range of adenylate energy charge observed in surviving mammalian cells (0.7-0.9), the rate of AMP-hydrolysing activity catalysed by the 5'-nucleotidase increased sharply with decreasing energy charge. The highest activity was observed at an energy-charge value of about 0.6. The response was also observed in the presence of Pi. No change in IMP-hydrolysing activity was observed in the physiological range of adenylate energy charge, but in the presence of Pi the activity gradually increased with increasing energy charge. These results suggest the possibility that this enzyme participates in production of adenosine, a vasodilator, during hypoxia and in removal of IMP, which accumulates during the hypoxia, in the heart.

5'-Nucleotidase↗
PubMed1986

Endomyocardial biopsy findings in pediatric patients with post myocarditic state.

Endomyocardial biopsy was performed on eight children 5 to 12 years old, who were in post myocarditic state. They were evaluated within 2 to 25 months (mean lyr and 1 m) after the onset of the symptoms. Two of the patients developed heart failure and six patients developed other cardiac manifestations such as syncope, palpitation or ECG abnormalities at onset. Definite elevation of viral antibody titer was observed in four patients. Radionuclide angiography was also performed in all eight patients. An abnormal perfusion area was observed in six patients as a focal hypoperfusion area by T1-201 myocardial imaging. Ejection fraction was examined by Tc-99m-HSA gated equilibrium ventriculography. LVEF was reduced in 3 patients and RVEF was reduced in 2 patients. Judging from the histopathological findings, these patients were divided into three categories: chronic or smoldering myocarditis (3 patients); healing or healed myocarditis (4 patients); and post myocarditic hypertrophy (1 patient). Measurement of left ventricular function was obtained by cardiac catheterization and left ventriculography (LVG), which revealed some abnormal findings such as increased left ventricular mass index, increased left ventricular end diastolic volume index (LVEDVI) and reduced left ventricular ejection fraction (LVEF). Therefore, endomyocardial biopsy findings of pediatric patients in a post myocarditic state reveal certain histopathological abnormalities even in the long-term follow-up period in the absence of cardiac dysfunction.

Biopsy↗