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Biomedical subjects

S Takada

Publications and source records attributed to S Takada.

At least 235 records · Page 13Linked to original sources
PubMed1989

Alteration of DNA primase activity by phosphorylation and de-phosphorylation of histone H1.

To investigate the effect of histone H1 on DNA primase activity, partially purified DNA primase from mouse FM3A cells was used. It was found that histone H1 dose dependently inhibited DNA primase. Interestingly phosphorylation of histone H1 reduced the inhibitory activity of the histone. However, de-phosphorylation of the phosphorylated histone H1 resumed the inhibitory activity of DNA primase. These findings lead us to the assumption that phosphorylation and de-phosphorylation of histone may regulate the cell cycle by controlling DNA synthesis through reverse inhibition of DNA primase.

Animals↗
PubMed1989

Clinical study of radioisotope clearance from the cerebrospinal fluid space using single photon emission computed tomography.

Radioisotope cisternography with statistical analysis was evaluated in 18 patients with suspected hydrocephalus shown by conventional CT, and 4 control patients. Regions of interest were located at cisterna magna, basal cistern, lateral cistern Sylvii, interhemispheric cistern, and lateral ventricle using three dimensional SPECT images. A value for the constant K was determined for each exponential radioactivity decay curve. On the basis of SPECT-derived K values our patients were grouped into hydrocephalus, nonhydrocephalus, and control patients. Twelve of 14 hydrocephalus patients were treated by shunt operation. Our less-invasive method showed reliable criteria for assessing the cerebrospinal fluid circulation.

Adolescent↗
PubMed1989

Infectivity of Cryptosporidium muris (strain RN 66) in various laboratory animals.

The infectivity of Cryptosporidium muris (strain RN 66), originally isolated from the house rat (Iseki 1986), to various laboratory animals was studied by transmission experiments. After oral inoculation with 1 x 10(6) oocysts, mice, guinea pigs, rabbits, dogs, and cats all discharged endogenously produced oocysts in their feces. Among these host species, mice and cats were highly susceptible to the parasite. The prepatent period for six 3-week-old specific pathogen-free (SPF) mice was 5 days postinoculation (PI), the patent periods varied between 34 and 75 days for each mouse, and the number of oocysts discharged per individual per day (OPD) was 11-46 x 10(6) at the maximum on days 16-26 PI. The total number of oocysts discharged per mouse during the patent period was estimated to be 170-560 x 10(6). Three inoculated cats (1-2 months old) also discharged a large number of oocysts for a long period. Guinea pigs, rabbits, and dogs showed low susceptibility to this strain; the OPD was extremely small and the patent periods were less than 3 weeks. The entire endogenous development of this parasite occurred in the stomach and not in the small and large intestines of these experimental animals. Because of this lack of host specificity, it is suspected that C. muris could be infective to humans, especially immunocompromised patients such as those with AIDS.

Animals↗
PubMed1989

Anterior rib strut grafting for the treatment of malignant lesions in the thoracic spine.

Anterior stabilization during thoracotomy, using the patient's own ribs, was carried out seven times in six subjects with malignant lesions of the thoracic vertebrae. The primary malignancy was lung carcinoma in four cases, thyroid carcinoma in one case, and alveolar soft tissue sarcoma in one. Resection of the lung tumor and spinal surgery were carried out simultaneously. Four of the six patients had complete paraplegia and two had partial paraplegia prior to the operation. After the decompression and anterior stabilization, three subjects responded well and three responded poorly because of respiratory insufficiency.

Adult↗
PubMed1989

Familial occurrence of impaired interleukin-2 activity and increased peripheral blood B cells actively secreting immunoglobulins in systemic lupus erythematosus.

PURPOSE: We tested the hypothesis that some abnormalities of immune functions are genetically controlled in patients with systemic lupus erythematosus (SLE). SUBJECTS AND METHODS: We used a phytohemagglutinin-induced interleukin-2 (IL-2) activity assay and a spontaneous plaque-forming cell assay to evaluate T-cell and B-cell function, respectively, in 34 clinically healthy family members of six SLE probands. RESULTS: Impaired IL-2 activity was found in 15 of the 29 consanguineous relatives. There was no relation between the household relatives and the nonhousehold relatives; none of the five nonconsanguineous household persons had abnormal results. Results for the B-cell assay were abnormal in 22 of the 29 consanguineous relatives. The B-cell abnormalities were more commonly observed in the consanguineous household relatives; four of the five nonconsanguineous household relatives also had abnormal assay results. CONCLUSION: The findings indicate that the impaired IL-2 activity in relatives appears to strongly correlate with a genetic relationship. Although the evidence favors a genetic basis for the B-cell abnormalities, environmental effects may also contribute to the familial occurrence of these abnormalities.

Adolescent↗
PubMed1989

Selective suppression of endogenous beta-globin gene expression by transferred beta-globin/TK chimeric gene in murine erythroleukemia cells.

To examine the effect of gene transfer on expression of the endogenous beta-globin gene in murine erythroleukemia (MEL) cells, a beta-globin/TK chimeric gene was introduced into MEL cells. In some of the transformants, expression of the endogenous beta-globin gene was only weakly induced with the addition of DMSO, while expression of the introduced beta-globin/TK chimeric gene was well induced. Suppression of the endogenous beta-globin gene is selective for beta-globin gene, since expression of alpha-globin gene was only weakly affected in its induction in the transformants. Analysis of nine individual transformants indicated that suppression of the endogenous gene correlates more closely with the transcriptional activity than the copy number of the exogenous gene. Thus, the selective suppression can be explained by competition of positive trans-acting factor(s), present in limiting amounts, with high copy number of the exogenous gene the conformation of which is active.

Animals↗
PubMed1989

A balance between self-renewal and commitment in the murine erythroleukemia cells with the transferred c-myc gene; an in vitro stochastic model.

When murine erythroleukemia (MEL) cells, having the transferred rat c-myc gene under the control of human metallothionein II gene promoter, are induced to differentiate with dimethyl sulfoxide (DMSO), the level of differentiation is dependent on the c-myc levels which are modulated by the Zn++ ion. The clonal transformant cell line (38-2) can continuously grow in the presence of both DMSO and Zn++ ion. The proportion of differentiated cells in a population of the continuous culture is strongly affected by the concentration of Zn++ ions. These results suggested that a balance between self-renewal and commitment to differentiation of MEL cells is determined by the c-myc level, and that this cell line may be suitable for studying the stochastic process of growth and differentiation of hemopoietic stem cells.

Animals↗
PubMed1989

Transport processes of 2-deoxy-D-glucose in erythrocytes infected with Plasmodium yoelii, a rodent malaria parasite.

The transport processes of D-glucose in Plasmodium yoelii-infected mouse erythrocytes were investigated using 2-deoxy-D-glucose (2DOG), a non-metabolizable analogue of D-glucose. Infected cells showed an increase in the uptake of 2DOG compared to uninfected controls, and an effect which was more prominent in cells with mature-stage parasites. Kinetic studies measuring the initial rates of 2DOG uptake revealed two components in infected cells with late trophozoite and schizont-stage parasites: a simple diffusion system and a carrier (transporter)-mediated system. The transporter was common for D-glucose and 2DOG and had a kinetic constant indicating a high affinity for 2DOG (the Km = 0.18 mM and the Vmax = 0.61 mmol/10(10) cells/min), as compared to the constant of the mouse erythrocyte carrier (the Km = 10 mM and the Vmax = 1.8 mmol/10(10) cells/min). Determination of the distribution of [3H]2DOG in infected cells and experiments with metabolic inhibitors indicated that the simple diffusion system localizes in the membrane of host cells and the transporter in the parasite plasma membrane. The parasite glucose transporter was much less sensitive to cytochalasin B than that of the host cells and the uptake of 2DOG via the transporter was dependent on energy. Based on these findings, the following features emerge: D-glucose first gains access to the cytosol of infected erythrocytes via the simple diffusion system, which appears after infection by the parasite, and an active uptake against the concentration gradient takes place at the parasite plasma membrane via the parasite glucose transporter in an energy dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Thienylpyrazoloquinolines with high affinity to benzodiazepine receptors: continuous shift from inverse agonist to agonist properties depending on the size of the alkyl substituent.

2-(5-Alkylthien-3-yl)-(1),2-(4-alkylthien-2-yl)-(2), and 2-(5-alkylthien-2-yl)-2,5-dihydro-3H-pyrazolo[4,3-c]quinolines (3) were prepared in four steps starting from ethyl 4-chloroquinoline-3-carboxylate (4) and hydrazinothiophene-carboxylates 5, 8, and 9. All the assayed compounds possessed high affinities for benzodiazepine receptors (Ki = 0.3-2.6 nM). The activities of agonists and inverse agonists were assessed on the basis of inhibition or facilitation of pentylenetetrazole-induced convulsions, respectively. Introduction of alkyl groups of different sizes into the unsubstituted inverse agonistic compounds results in a corresponding shift in the activity from an inverse agonist to an antagonist to an agonist. The susceptibility of such a shift increases in the order of 1 less than 2 less than 3. This tendency may be explained by slight differences in the geometry of the alkyl substituents among the three series.

Animals↗
PubMed1989

Intrabronchial neurilemmoma--review of cases in Japan.

We recently encountered a case of intrabronchial neurilemmoma. The patient was a 15-year-old boy who had a wheeze. After observation with a bronchofiberscope, a wedge resection of the left main bronchus was performed. No postoperative complications nor recurrence was seen. To date, five cases of intrabronchial neurilemmoma have been reported in the Japanese Journals. Surgical removal was performed in 4 of 5 and bronchofiberscopic excision in 1. This paper summarizes the clinical features of these cases as well as our own case.

Adolescent↗
PubMed1989

Effects of thiazide diuretic on vascular eicosanoid system of spontaneously hypertensive rats.

To assess the role of the vascular eicosanoid system in thiazide therapy, we examined the aortic eicosanoid system of spontaneously hypertensive rats (SHR) treated with trichloromethiazide for 2 weeks. The blood pressure reduction caused by the thiazide treatment was associated with a significant decrease in vascular vasodepressor prostacyclin (PGI2) generation, whereas neither nifedipine nor captopril treatment lowered vascular PGI2 generation. The thiazide diuretic directly lowered PGI2 synthase activity in cultured vascular smooth muscle cells (VSMC), thereby decreasing PGI2 generation in the VSMC and probably in the aortic wall. This direct inhibitory effect on vascular PGI2 generation was not observed with either furosemide or indapamide. Thus, vascular PGI2 generation is reduced with trichloromethiazide, partly through its direct inhibition of PGI2 synthase; this has possible relevance to the non-beneficial effects of thiazide diuretics on the vascular sclerotic changes.

Animals↗
PubMed1989

Analysis of the expression of two phosphoglycerate kinase genes in a mouse cultured cell line during activation and inactivation of the c-myc gene.

The effect of a change in the concentration of c-myc protein on the expression of genes for two phosphoglycerate kinase isozymes was investigated. The steady state levels of messenger ribonucleic acids (mRNAs) for sperm-type and non-sperm-type proteins were determined by blot hybridization using the RNA of the mouse cell line 38-2 containing the inducible rat c-myc gene cultured under various conditions. Without induction the c-myc gene. mRNA for non-sperm-type protein was detected at a level that remained essentially constant during both activation and inactivation of the c-myc gene. mRNA for sperm-type protein was not detected in 38-2 cells cultured under any conditions used. Change in the amount of c-myc protein alone does not appear to bring about a switch of the expression of the two phosphoglycerate kinase genes during spermatogenesis in mouse testis.

Cell Line↗
PubMed1989

[Molar size sequence in seven species of Cercopithecidae].

The size sequence of the molar teeth in three genera, including seven species, of the Cercopithecidae was examined on the basis of mesiodistal and buccolingual crown diameters, and rectangle measurements (mesiodistal d. X buccolingual d.). The determination of molar size order was estimated by the three methods of mean values, size sequences and reductive indices (M2/M1, M3/M1). The results obtained are summarized as follows: 1. The molar size sequence of the seven species. The pattern of sequence in the molars of the Cercopithecidae was divided into six types: (I) M1 less than M2 less than M3 or (M1M2) less than M3, (II) M1 less than (M2M3), (III) M1 less than M3 less than M2, (IV) (M1M2M3), (V) (M3M1) less than M2, and (VI) M3 less than M1 less than M2 or M3 less than (M1M2). 2. The upper molars. i) The most frequent pattern of mean values found was type II for all the species of the Macaca and Colobus. The two species of Cercopithecus showed predominantly the characteristics of types III, IV and V. ii) The molar size sequence individual data revealed that in the mesiodistal crown diameter types I and II were distributed frequently in the Macaca, types IV and V in the Colobus, and type VI in the Cercopithecus. The reduction of the third molar, therefore, seemed to be more pronounced in the Cercopithecus when compared with the other two genus, Macaca and Colobus, because type VI is the type with more size reduction in the third molar. In the case of the buccolingual crown diameters, the most common size sequences were found in types II and III for the Macaca and Colobus. In the Cercopithecus, however, type V exceeded other types in frequence. iii) The results of the reductive indices showed that the second molars in the Colobus were greatly reduced compared to the first, followed by those of the Cercopithecus and Macaca. In the third molar reduction, the Cercopithecus had a relatively small third molar compared to the first, following the Colobus and Macaca. 3. The lower molars. i) The pattern in the mean values were frequently found to be type I for the Macaca and Colobus, and types III and II for the Cercopithecus. ii) The size sequence in the frequency of the mesiodistal crown diameter was well presented in type I for the Macaca and Colobus, while types IV and V were distributed frequently for Cercopithecus in which the reduction of the third molar was noticeable.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Possible involvement of the CD4 molecule in a late activation event on CD4+ T cell proliferation in the human autologous mixed lymphocyte reaction.

CD4 monoclonal antibody (MoAb) was able to inhibit T cell proliferation induced in an autologous mixed lymphocyte reaction (AMLR). The effect of CD4 MoAb on cellular proliferation appears to be directly exerted on CD4+ T lymphocytes, and to be due to inhibition of a post-activation event, since the CD4+ T cell proliferation that occurs after an activation pulse of 24 h with autologous non-T cells could be inhibited when CD4 MoAb was added after, but not during, the pulse period, and the inhibition of autologous MLR-induced CD4+ T cell proliferation by CD4 MoAb was observed even if the Moab was added as late as 72 h after the initiation of culture. The presence of CD4 MoAb did not affect the production of interleukin 2 (IL-2). CD4 MoAb had, however, an inhibitory effect on the expression of IL-2 receptors, such that addition of exogenous IL-2 at the initiation of culture did not restore the AMLR-induced CD4+ T cell proliferation. These results indicate that the hindrance of the recognition of HLA class II products is not the only target of the CD4 MoAb effect in the autologous MLR. Rather, the binding of CD4 MoAb to CD4+ T cells interferes with a late event because it is capable of abolishing the proliferative activity of fully activated CD4+ T cells. The data are compatible with the idea that perturbation of the CD4 molecules can transmit a negative signal to CD4+ T cells.

Antibodies, Monoclonal↗
PubMed1989

Stimulation of DNA chain initiation by a protein factor (NPF-1) from rat liver of different ages.

DNA Polymerase-alpha/primase complexes have been isolated from human neuroblastoma IMR-32, embryonic chicken brains (ECB) and rat prostate tumor PA-3 cells. In the presence of (NH4)2SO4 the major part (90%) of primase activity is released from the Pol-alpha/primase complex. A novel hydrophobic interaction column was used for purification of the primase from PA-3 cells. A nuclear protein factor (NPF-1) that stimulates DNA pol-alpha/primase activity has been purified from rat liver of various ages (3-6 months). The nuclear protein factor which only stimulates the primase activity is under investigation. The monoclonal antibodies (SJK 132-20 and 237-71) were used to detect DNA pol-alpha polypeptides from 11- to 19-day-old embryonic chicken brains.

Aging↗
PubMed1989

Activated N-ras gene was found in human hepatoma tissue but only in a small fraction of the tumor cells.

Activated N-ras gene was isolated from human hepatoma tissue by DNA transfection assay coupled with the neomycin selection method and molecular cloning and a point mutation in the codon 61 (CAA----AAA) was noted. However, examination of the proportion of the mutated N-ras gene in the tumor part by molecular cloning and by hybridization using synthetic oligonucleotide probes indicated that the mutated gene occurred with very low frequency. The activated N-ras gene appears located only in a small fraction of the tumor cells. The experimental data indicate activation of this gene as possibly not the major cause of carcinoma, but rather a manifestation of tumor heterogeneity.

Animals↗
PubMed1989

[Roles of vascular and renal thromboxanes in the antihypertensive effects of alpha 1 adrenoceptor antagonists].

In order to assess the roles of vasoconstrictor thromboxane in the antihypertensive action of alpha 1 adrenoceptor antagonist, we explored the influences of OKY-046, a selective thromboxane inhibitor, on the antihypertensive effects of bunazosin in spontaneously hypertensive rats (SHR). 2-week antihypertensive treatment with bunazosin (0.5 mg/kg/day) did not produce a significant decrease of systolic blood pressure in SHR, as compared to untreated controls. The blood pressure reduction was associated with a decrease of PGI2/TXA2 in vascular eicosanoids generation (p less than 0.02) and an increase of TXA2 excretion in urine (p less than 0.05). A combination treatment with OKY-046 almost completely abolished the enhanced TXA2 generation in the vascular wall and kidney, which was strikingly associated with a potentiation of the blood pressure reduction by bunazosin treatment (176 vs 186 mmHg, p less than 0.01). Bunazosin directly stimulated TXA2 biosynthesis in vascular smooth muscle cells in culture in a dose-dependent manner. Thus, these data clearly indicate that bunazosin, a quinazoline derivative, enhances vasoconstrictor TXA2 system in the vascular wall and kidney possibly through direct actions, which would attenuate the antihypertensive effects of alpha 1 adrenoceptor antagonism by bunazosin treatment.

Adrenergic alpha-Antagonists↗