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Biomedical subjects

T Sekiguchi

Publications and source records attributed to T Sekiguchi.

At least 181 records · Page 10Linked to original sources
PubMed1984

Cytidine 5'-diphosphate reductase and thymidine kinase activities in phytohemagglutinin-stimulated lymphocytes of normal subjects of various ages and patients with immunodeficiency.

The activities of CDP reductase and thymidine kinase in 10(6) to 5 X 10(6) phytohemagglutinin (PHA)-stimulated lymphocytes isolated from 2 to 5 ml of peripheral blood of individual subjects were measured. The activities of CDP reductase (pmol/h/10(7) cells) and thymidine kinase (nmol/h/10(7) cells) were high in infants, 698 +/- 307 and 64.2 +/- 20.2, constant in subjects of 1-40 years old, 401 +/- 181 and 38.1 +/- 15.3, and low in persons of more than 80 years old, 121 +/- 113 and 22.3 +/- 17.8, respectively. The ratio of thymidine kinase to CDP reductase activity increased with age, indicating that dependency on the salvage pathway of DNA synthesis in lymphocytes increased with age. The activities of CDP reductase and thymidine kinase were reduced in patients with the hyperimmunoglobulin E syndrome, congenital cytomegalovirus infection, anhidrotic ectodermal dysplasia with hyperimmunoglobulin A, Bloom's syndrome, immunodeficiency with hyperimmunoglobulinemia, and Down's syndrome. The clinical symptoms of these diseases seem to be due to impaired DNA synthesis of PHA-stimulated lymphocytes, but the degrees of reduction of enzyme activities were generally greater than that of thymidine incorporation in these patients.

Adolescent↗
PubMed1984

Adverse effect of nifedipine on left ventricular obstruction detected by pulsed Doppler echocardiography.

The effect of nifedipine on the ejection flow pattern in the left ventricular outflow tract was observed using pulsed Doppler echocardiography in 6 patients with hypertrophic cardiomyopathy. After sublingual administration of nifedipine (10 mg) to 1 patient, the turbulent ejection flow pattern became more marked and increased in duration compared with the initial state. An increase in turbulence in the left ventricular outflow tract may increase the pressure gradient between the left ventricle and the aorta. Nifedipine appeared to have the potential of adverse action on left ventricular outflow obstruction.

Blood Pressure↗
PubMed1984

[Comparative study on the inhibitory effect of glucagon and secretin on the gastroduodenal motility in man].

Manometric study was performed to compare the inhibitory effect of glucagon and secretin on the gastroduodenal motor activity by infused catheter method. The subjects consisted of 3 healthy volunteers and 7 patients with peptic ulcer and other diseases. The following results were obtained. After the intravenous administration of glucagon (1 mg), the motor activity of the stomach and duodenum was inhibited promptly. According to statistic evaluation, the contraction numbers and motility index decreased significantly during 25 minutes compared with the basal values in both stomach and duodenum. After the administration of secretin (100 units), gastric motor activity was markedly inhibited, although duodenal motility increased during 10 minutes due to the initiation of secretin-induced migrating motor complex. The contraction numbers and motility index in stomach decreased significantly during 20 minutes after the administration. The inhibitory effect of glucagon was more remarkable in duodenum than in stomach. On the other hand, secretin was more effective in stomach than in duodenum.

Adult↗
PubMed1984

[Two-dimensional pulsed Doppler echocardiographic estimates of cardiac output in man: sampling at the entrance to the main pulmonary artery].

To assess the feasibility and accuracy of measuring cardiac outputs (CO) by two-dimensional (2-D) pulsed Doppler echocardiography, taking samples at the main pulmonary artery just beyond the pulmonary valve, 62 cardiac patients were studied. The results obtained were compared with CO values determined by the thermodilution technique. 2-D Doppler echocardiograms suitable for computing CO were recorded in 37 (60%) of 62 patients. A significant correlation (r = 0.64) was observed between 2-D echocardiographic and angiographic pulmonary ring diameters (PRD), but the echocardiographic PRD was smaller than that of angiography by 0.4 +/- 0.2 cm. Thus, to compute the Doppler CO, the echocardiographic PRD had to be corrected by the difference between the angiographic and echocardiographic PRD. The angle between the ultrasound beam and the pulmonary blood flow was 7.8 +/- 6.1 degrees (0 approximately 18 degrees), and this was negligible for computing the Doppler CO. Even in cases with atrial fibrillation, the Doppler CO could be computed as is done in sinus rhythm. The correlation between the thermodilution and Doppler CO was highly significant (r = 0.92), and the regression equation was as follows: Thermodilution CO = 1.09 X (Doppler CO)-0.19 The difference between thermodilution and Doppler CO was 3.4 +/- 10.0% (-21 approximately +21%). Comparing the differences in CO between the thermodilution and dye-dilution techniques, those between thermodilution and the Fick methods, and those among thermodilution methods reported in the literatures, the difference in this study was not large and was acceptable. Thus, measurement of CO by pulsed Doppler echocardiography, with sampling entrance to the main pulmonary artery, can be used clinically.

Adult↗
PubMed1984

Extrachromosomal circular DNAs in interspecific mouse-rat reconstituted cells.

Several clones of reconstituted cells were isolated by fusion of karyoplasts of mouse melanoma B16 cells with cytoplasts of rat myoblastic L6 cells and processed by the mica-press-adsorption method for electron microscopy. Extrachromosomal small circular DNAs of less than 1 micron in contour length (smaller circular DNA) were present in both parental cells, and circles larger than 1 micron (larger circular DNA) were found more frequently in reconstituted cells at an early stage after the clonal isolation. Mitochondrial DNA was not released from mitochondria by this method. The new phenotypes of reconstituted cells were stable, but larger circles were lost after prolonged cultivation of the cells. The possibility that the larger circular DNAs result from intrachromosomal DNA rearrangement induced by rat cytoplasts is discussed.

Animals↗
PubMed1983

DNA from alkalophilic Bacillus can transform B. subtilis to alkalophily.

On incubation of B. subtilis RM125(arg 15 leuA8 rM- mM-) with DNA from alkalophilic Bacillus, the transformants (Arg+Leu- or Leu-Arg+) appeared at pH 10. The transformants were able to grow even at pH 7. Alkalophilic Bacillus was resistant to bacteriophages ø105D1C2.1012 grown on B. subtilis 1012(r-mM+) and ø105D1C2.ISMR4 grown on B. subtilis ISMR4(rM+rR+mM+mR+), but the recipient B. subtilis and the transformant(Arg+Leu-) were susceptible to both of the bacteriophages. The results indicate that the transformant is a B. subtilis derivative and that alkalophilicity of alkalophilic Bacillus was transferred to B. subtilis.

Alkalies↗
PubMed1983

Transformation of temperature-sensitive growth mutant of BHK21 cell line to wild-type phenotype with hamster and mouse DNA.

A temperature-sensitive (ts) mutant, tsBN2, which was derived from BHK21 and is defective in the regulatory mechanism for chromosome condensation, was transformed to the temperature-resistant (ts+) phenotype by means of DNA-mediated gene transfer with hamster and mouse DNA. Treatment of mouse DNA with the restriction enzymes EcoRI, HindIII, PstI and SalI, but not with XhoI, almost completely abolished the transforming activity. A fluctuation test, originally devised by Luria and Delbrück, was used to estimate the reversion and transformation frequencies of tsBN2 cultures.

Animals↗
PubMed1983

Effect of mitochondrial DNA composition on the cellular properties of interspecific hybrid cells.

Four subclones with single species of mitochondria and three subclones with both parental mitochondria were isolated from a mouse-rat hybrid cell line H2. The effects of the coexistence of different species of mitochondria on cellular properties were examined in these clones. Growth properties were studied by comparing the plating efficiencies and doubling times. The numbers of growing colonies and the doubling times of all the subclones were found to be almost the same, indicating that these growth properties were not affected by the presence of both mouse and rat mitochondria within the cells. The correlation between the expression of chloramphenicol (CAP)-resistance and the relative contents of mtDNA of CAP-resistant (CAPr) rat and CAP-sensitive (CAPs) mouse parent cells in the subclones were also examined. The expression of CAP resistance was measured as the relative plating efficiency. Subclones with a high content of mtDNA from CAPr rat parent cells showed high relative plating efficiency.

Animals↗
PubMed1983

Two distinct types of mitochondrial DNA segregation in mouse-rat hybrid cells. Stochastic segregation and chromosome-dependent segregation.

Two distinct patterns of mitochondrial DNA (mtDNA) segregation were found in different mouse-rat hybrid cell lines. On mouse-rat hybrid cell line, H2, retained complete sets of chromosomes and mtDNAs of both mouse and rat. Even after cultivation for about one year after cloning, the H2 cell population still retained both parental mtDNAs. However, when mtDNAs of H2 subclones were examined, it was found that some individual cells in the H2 cell population contained only mouse or only rat mtDNA, although they still retained complete sets of both kinds of parental chromosomes. This type of mtDNA segregation, named stochastic segregation, is bidirectional and may be caused by the repetition of random sharing of mouse and rat mtDNAs with daughter cells. This segregation occurred spontaneously during long-term cultivation. The second type of mtDNA segregation, named chromosome-dependent segregation, was found in the other mouse-rat hybrid cell lines that segregated either mouse or rat chromosomes. In these hybrid cells, chromosomes and mtDNA of the same species co-segregated. This second type of segregation is unidirectional. The types of mtDNA segregation appear to depend on the stability of the parental chromosomes in the hybrid cells. When both mouse and rat chromosomes retain stably, mtDNA shows stochastic segregation. On the contrary, when either species of chromosomes is segregated from the cells, mtDNA shows chromosome-dependent segregation.

Animals↗
PubMed1983

Intracellular location of small circular DNA complexes in mammalian cell lines.

For determination of the cellular location of small polydisperse circular DNA complexes, rat myoblastic L6 cells, HeLa cells, and mouse L cells were enucleated and processed by the micapress-adsorption method for electron microscopy (H. Yamagishi, T. Kunisada, and T. Tsuda, 1982, Plasmid 8, 299-306). Small circular DNA complexes from intact cells showed a heterogeneous size distribution of from 0.1 to more than 2 micron with a mean contour length of 0.6 to 0.8 micron, like that of covalently closed circular DNAs. Cells contained 400 to 1200 copies. The size distribution in the cytoplasts was narrow and the number-average length was 0.3 to 0.4 micron, whereas that in L6 karyoplasts was wide and the average length was 0.9 micron. The longer circular complexes appeared to be absent from the cytoplasts. The origin and biological functions of these complexes are discussed in relation to the cellular locations of the complexes.

Animals↗
PubMed1983

Recovery of a hybrid vector, derived from bovine papilloma virus DNA, pBR322 and the HSV tk gene, by bacterial transformation with extrachromosomal DNA from transfected rodent cells.

A bovine papilloma virus (BPV)-pBR322-derived recombinant plasmid carrying a 2-kb fragment of Herpes simplex virus DNA containing the thymidine kinase (tk) gene is capable of transforming tk- cells of mouse L and Syrian hamster BHK21 lines to tk+. In transformed cells a small proportion of the plasmid DNA is present as extrachromosomal elements while the remainder appears to be integrated into the genome. It was possible to recover plasmids indistinguishable from the input DNA by transformation of Escherichia coli bacteria with low-molecular-weight DNA isolated from the transformed mouse and hamster cells and consisting of BPV-pBR322-HSV tk+ plasmids.

Animals↗
PubMed1983

Protein synthesis and tumorigenicity of the cytoplasmic hybrid between rat yolk sac tumor and mouse fibroblastic cell line.

Cytoplasmic hybrid (cybrid) cell lines were formed by fusing whole cells of rat yolk sac tumor cell line (EST-II) with cytoplasts of mouse fibroblastic cell line (B-82cap), a variant of mouse L cell line that is deficient in thymidine kinase (TK-) and resistant to chloramphenicol (capr). The cybrid cell line with the nucleus of EST-II and cytoplasma of B-82cap was successfully obtained using double selection with HAT and chloramphenicol-containing medium. The cybrid's ability to synthesize proteins such as albumin, alpha-fetoprotein, gamma-EST, and gamma-GTP was found to be approximately one-fourth that of the nuclear donor, EST-II, at a early time of growth in culture, but this was followed by a gradual increase during the period of observation. The nude mice undergoing subcutaneous transplantation of 1 X 10(6) cells of EST-II and cybrid were killed by the tumor growth, with the survival time being 56 +/- 11 and 105 +/- 25 days, respectively. The histologic findings of cybrid tumor closely resembled those of the nuclear donor, EST-II. These facts suggest that factors from both the nucleus and cytoplasma will be able to affect the gene expression of the cybrid cell line.

Animals↗
PubMed1983

Effects of high potassium depolarization, carbachol and oxytocin on the Lanthanum-resistant 45Ca fraction in rat myometrium.

The effects of high potassium, carbachol and oxytocin on 40Ca-45Ca exchange in the estradiol-treated rat uterine longitudinal muscle were compared with those in the ovariectomized one using the modified "Lanthanum Method." The treatment of estrogenized or ovariectomized myometrium with 60 mM K+ significantly increased the 45Ca space at 5-, 10-, 30- and 60-min incubation times. The increase in the 45Ca by high-K+ in the estrogenized myometrium was much greater than that in the ovariectomized one. Carbachol (2 X 10(-6) M) had little influence on the 45Ca space at all incubation periods with the exception of the 10-min one in both uteri. The higher concentration of carbachol (2 X 10(-4) M) in the estrogenized myometrium produced a marked increase in the 45Ca space after the 10-min incubation, while in the ovariectomized uterus, a slight increase in the 45Ca space was observed at the 10- and 30-min incubation times. The increase in the 45Ca space by 2 X 10(-4) M carbachol in the estrogenized myometrium was greater than that in the ovariectomized one. Oxytocin (10(-4) and 10(-3) units/ml) increased the 45Ca space at and after the 10-min incubation times in the estrogenized uterus, while in the ovariectomized uterus, oxytocin (10(-3) and 10(-2) units/ml) showed little influence on the increase in the 45Ca space. The increase in 45Ca space by carbachol and oxytocin was inhibited by papaverine. These results suggest that differences in dependence upon Ca2+ in the medium may exist in contractions induced by high-K+, carbachol and oxytocin in the uterine smooth muscle and that the contractions in the estradiol-treated myometrium may be more dependent upon extracellular Ca2+ than those in the ovariectomized one.

Animals↗
PubMed1983

Interdigestive motor activity in health and disease.

Interdigestive contractile activity in the gastrointestinal tract was measured in dogs and humans. During the interdigestive state, it was found that in healthy dogs and humans, cyclically-recurring strong contractions occurred in the stomach at approximately 100 min intervals and migrated through the small bowel in a caudal direction. The interdigestive contractions consist of three phases, phase I being quiescent while phases II and III are contractile. Phase II contractions resemble those in the digestive state and therefore mix the contents, and phase III contractions are strong in contractile force and consequently squeeze and expel the contents in a caudal direction. Intraduodenal pH changes were studied together with motor activity and it was found that intraduodenal pH remained at a slightly alkaline level during the interdigestive state in the dog; however, in human studies, it was revealed that intraduodenal pH drops below pH 7.0 only during the phase II period. These characteristic contractile changes in the interdigestive state are controlled at least in part by the cyclic increase in motilin concentration in the plasma, but it is not known what regulates the cyclic release of motilin during the interdigestive state. Feeding promptly eliminates changes in the plasma motilin concentration. It is not known whether other gut hormones are involved in the regulation of these specific motor changes in the interdigestive state. One of the typical disorders in motor activity was found in duodenal ulcer. In duodenal ulcer patients, the most characteristic difference from normal subjects was that the duration of phase II activity was significantly prolonged and intraduodenal pH fluctuated widely and intensely during the period. Hypersecretion of acid is well known to be the specific feature of this disease. However, the present study clearly indicates that spontaneous acid secretion per se or vagally induced acid secretion during phase II disturbs the interdigestive motor cycle and, in consequence, leads to the development of ulcers due to the fact that acid contents alone are continuously mixed in the stomach over the prolonged period of phase II activity. These findings lead us to a better understanding of the true pathogenesis of this disease as well as effective treatment of patients from a radical as well as symptomatic standpoint.

Adult↗