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Biomedical subjects

R Itoh

Publications and source records attributed to R Itoh.

18 recordsLinked to original sources
PubMed1992

A comparative study on tissue distribution and metabolic adaptation of IMP-GMP 5'-nucleotidase.

1. Activity of a cytoplasmic 5'-nucleotidase which preferentially hydrolyzes IMP and GMP (IMP-GMP 5'-nucleotidase) was determined by a specific immunochemical method in two species of birds and two species of mammals. 2. The activity was markedly high in avian liver, and it increased two-fold in response to a high protein diet in chicken liver. 3. In mammals, the activity was high in testis and spleen. In the rat, the activities in liver, kidney and heart extracts increased by about 30% in response to the high protein diet, while they increased three-fold in regenerating liver. 4. Low activities were detected in skeletal muscles and in erythrocytes of all the species studied.

5'-Nucleotidase↗
PubMed1992

Pulmonary metastatic nodules: CT-pathologic correlation.

To elucidate the characteristics of pulmonary metastatic nodules on high-resolution computed tomographic (HRCT) scans, a correlative computed tomographic (CT)-pathologic study was performed with five human lungs after autopsy. The relationship of metastatic nodules to pulmonary vessels was studied with HRCT scans, radiographs of the specimen, and stereomicroscopic study in 264 nodules 0.6-9.0 mm in diameter. On radiographs and stereomicroscopic images, 190 small nodules (less than 3 mm in diameter) were in contact with the pulmonary lobule on the central bronchovascular bundles (n = 33 [17.4%]), located between the central bronchovascular bundle and the perilobular structure (n = 127 [66.8%]), or attached to perilobular structures (n = 30 [15.8%]). On HRCT scans, 21 small nodules (11.1%) were located on the central bronchovascular bundle; 130 small nodules (68.4%), between the central bronchovascular bundle and the perilobular structure; and 39 small nodules (20.5%), on the perilobular structure. On radiographs and stereomicroscopic images, 43 of 74 large nodules (greater than 3 mm in diameter) (58%) compressed both bronchovascular bundles and perilobular structures. The central bronchovascular bundle was invaded in only 13 large nodules (18%).

Humans↗
PubMed1992

Multivariate analysis of dietary habits in 931 elderly Japanese males: smoking, food frequency and food preference.

To define the influence of smoking on dietary patterns and food preference in elderly Japanese, a mail survey was conducted on about 3000 subjects aged 65 years and older. A multivariate analysis of dietary frequency data regarding 15 food items on 931 male respondents suggested that frequency of intake of plant food, including vegetables and fruits, was lower in smokers than in nonsmokers. Another multivariate analysis of food preference data regarding 18 food items on the same subjects suggested that smoking decreased the desire for plant food.

Aged↗
PubMed1992

Familial spinal xanthomatosis with sitosterolemia.

A family with multiple spinal xanthomas and sitosterolemia is described. A 48-year-old woman presented with paraplegia due to multiple intradural extramedullary tumors. The patient also showed marked tendon xanthomas and analysis of sterol composition in both plasma and the xanthoma established the diagnosis of the rare inherited metabolic disease, sitosterolemia and xanthomatosis. Two other siblings in the family presented with marked tendon xanthomas and coronary atherosclerosis, but did not show any neurological signs or symptoms. Magnetic resonance imaging (MRI) study revealed multiple intradural extramedullary tumors in spinal canals of the proband and her sister, but not in the other affected sibling (brother). This is the first report of familial occurrence of multiple extramedullary spinal tumors due to the inherited metabolic abnormality.

Cholesterol↗
PubMed1992

Scanning electron microscopic study on the lingual papillae in the Manchurian chipmunk, Tamias sibiricus asiaticus.

The superfacial structures of the tongues in the Manchurian Chipmunk, Tamias sibiricus asiaticus, were observed by scanning electron microscope. The tongues were long, tapering, narrow and thick with a long apical free portion and a small lingual prominence in the posterior half. In this animal, three circumvallate papillae were present in an inverted triangle, a minority of conical papillae on the pharyngeal part and parallel large conical papillae on the lateral border. The fungiform papillae were scanty on the dorsal surface. These characters suggested this animal was more primitive than the others in rodents.

Animals↗
PubMed1992

[Estimation of medroxyprogesterone acetate against a human endometrial tumor constituted from the established Ishikawa cancer cells by a subrenal capsule assay].

In order to establish a sensitivity test system for the evaluation of anti-cancer hormonal agents, we tried a long-term subrenal capsule (SRC) assay, using nude mice with a transplanted solid tumor of endometrial cancer cells (Ishikawa's line). Unlike DNA-affecting agents, anti-cancer hormonal agents exert cytostatic effects rather than cytocidal effects, and their evaluation in a short period is considered to be inaccurate. Our test system is somewhat difficult in terms of technique, but it is useful since it can (1) evaluate the agents in the relatively short period of 28 days and (2) compare the cytostatic anti-tumor efficacy of two or more agents under the same conditions. The rate of successful tumor transplantation in nude mice in our system is very high, i.e., more than 90%. Although there are some points which need improvement, our system is considered to be useful as an assay system for the development of anti-cancer hormonal agents and other similar chemotherapeutic agents for cancers. When medroxyprogesterone acetate (MPA) was evaluated by means of this system, the administration period, as well as the dosage, was found to be important.

Animals↗
PubMed1992

[Effect of high-dose medroxyprogesterone acetate on coagulative and fibrinolytic factors in patients with gynecological cancers].

Medroxyprogesterone acetate (MPA), which is widely used clinically as an anticancer steroid preparation, is a very useful drug that seldom causes severe side effects such as bone marrow suppression, and can be dispensed at the outpatient clinic for an oral administration at home to the advantage of QOL. Recently however, there have been several reports suggesting its relationship with thrombosis. We measured t-PA, protein C, factor X, AT III, TAT, plasminogen, PIC, fibrinogen, and D-dimer in 11 patients with gynecologic malignancies who are treated with MPA (600 mg/day) and 11 controls. Then we examined the effects of the drug on blood coagulation and fibrinolytic activities. No changes in these parameters clearly suggested thrombogenesis in either group at this measurement or during the observation period (17 months at the maximum). The present study found no remarkable abnormalities in the blood coagulation and fibrinolytic activities. Thus, to avoid the use of MPA to patients at risk is considered to be the most important precaution for prevention of thrombosis.

Antithrombin III↗
PubMed1991

Nutritional status of vitamin A in a healthy elderly population in Japan.

In this study nutritional status of vitamin A (VA) in a healthy elderly population in Japan was examined. Healthy elderly volunteers with mean age of about 67 at the start of the study were recruited. Analysis of serum VA concentration was carried out four times in two consecutive years. No deficient subject was detected from the serum VA concentration. Only small percentages were assessed to be in a low or marginal VA status. Consequently, the nutritional status of VA in the elderly Japanese seemed to be adequate judging from the serum VA concentration. Contrary to that, mean values of daily dietary intake of VA in both females and males were almost acceptable but the respective values varied over a wide range with no correlation with the serum VA concentrations. Accordingly, serum VA concentration provided a more definitive evaluation to assess VA nutriture than its dietary intake.

Aged↗
PubMed1991

The interrelation of urinary calcium and sodium intake in healthy elderly Japanese.

To evaluate whether habitual excess sodium intake is significant as a risk factor for calcium loss in elderly Japanese, a relationship between calcium excretion and sodium excretion was studied in 39 male and 44 female Japanese, aged 60 and over. They are healthy, free-living and consuming a self-selected diet. A significant positive correlation between urinary calcium excretion and sodium excretion per 24-hour was observed both in males (r = .415, p less than 0.01) and in females (r = .330, p less than 0.05). The relationship was still significant even after adjustment for sex, age, body mass index, alkaline phosphatase levels and protein as well as calcium and phosphorus intake. It was estimated that the increase in urinary calcium excretion was about 1.0 mmol/day per 100 mmol increase in urinary sodium excretion.

Aged↗
PubMed1979

Chicken liver amidophosphoribosyltransferase. Ligand-induced alterations in molecular properties.

A homogeneous amidophosphoribosyltransferase (EC 2.4.2.14) preparation, which was sensitive to purine nucleotide inhibitors, was obtained from chicken liver. From the result of sodium dodecyl sulfate polyacrylamide gel electrophoresis, the subunit weight was estimated to be approximately 58 000. In Tris-HCl buffer, the predominant form of the enzyme had an S20,w of 6.5, Strokes radius of 40 A, and estimated molecular weight of 110 000. Incubation with 5-phosphoribosyl 1-pyrophosphate or Pi resulted in an increase in the S20,w to 9.1--9.5, Strokes radius 50 A, and estimated molecular weight to 200 000. Incubation of the large form with AMP led to a decrease in the molecular wight of the enzyme. It is concluded that chicken liver amidophosphoribosyltransferase is an allosteric protein whose activity is regulated by a series of conformational changes induced by a number of ligands.

Adenosine Monophosphate↗
PubMed1976

Pigeon liver amidophosphoribosyltransferase. Ligand-induced alterations in molecular and kinetic properties.

Amidophosphoribosyltransferase (EC 2.4.2.14) has been partially purified from pigeon liver, and ligand-induced alterations in molecular and kinetic properties have been studied. In Tris-HCl buffer the predominant form of the enzyme has an s20,w of 5.9 +/- 0.7, Stokes radium of 42 A, and estimated molecular weight of 102,000. Incubation with phosphoribosylpyrophosphate (PP-ribose-P) results in an increase in the s20,w to 7.9 +/- 0.6, Stokes radius to 53 A, and estimated molecular weight to 172,000. Incubation of this larger form with purine ribonucleotides leads to a decrease in the molecular weight of amidophosphoribosyltransferase that is proportional to the concentration of purine ribonucleotide. Purine ribonucleotides produce sigmoidal kinetics with respect to the substrate PP-ribose-P, with Hill coefficients of 1.4 to 1.6 and 1.8 to 2.0 in the presence of AMP and GMP, respectively. Incubation with 0.6 M KCl leads to sigmoidal kinetics. Hill coefficient of 1.8 and dissociation of the larger form of amidophosphoribosyltransferase. Inorganic phosphate has complex effects upon the enzyme. In 25 mM potassium phosphate buffer the enzyme aggregates to a large form with an s20,w of 8.3 +/- 0.2, Stokes radius of 53 A, and estimated molecular weight of 181,000. Inorganic phosphate and PP-ribose-P both stabilize the enzyme to storage in vitro at 4 degrees. However, inorganic phosphate is 4 times more effective than PP-ribose-P in preventing inactivation of the enzyme by sodium dodecyl sulfate. Inorganic phosphate produces sigmoidal kinetics with respect to PP-ribose-P, Hill coefficient of 1.5. The interaction coefficients for AMP and GMP are reduced from 1.8 to 1.2 and 2.2 to 1.4, respectively, in the presence of 25 mM potassium phosphate. It is concluded that pigeon liver amidophosphoribosyltransferase is a complex allosteric protein whose activity is regulated by a series of conformational changes induced by a number of ligands.

Adenosine Monophosphate↗