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Biomedical subjects

T Sekine

Publications and source records attributed to T Sekine.

At least 271 records · Page 15Linked to original sources
PubMed1981

Influence of pancreatic duct ligation on gastric acid secretion.

The influence of pancreatic duct ligation (PDL) on gastric secretion was investigated in dogs with a Heidenhain pouch. A test meal was given to the dogs before PDL, and following PDL the dogs were administered with the test meal mixed with pancreatic enzymes and with the test meal alone in succession. The responses to the test meal were examined in the control period and every one week for a period of 1 to 6 weeks following PDL to identify the changes in gastric acid secretion, serum gastrin levels, immunoreactive glucagon (IRG) levels and immunoreactive insulin (IRI) levels. Gastric acid secretion in response to food stimulations markedly increased after PDL. However, the acid secretion was significantly inhibited by the administration of pancreatic enzymes. Serum gastrin levels began to increase from the second week and continued to increase until the sixth week after PDL, revealing no effect of pancreatic enzymes. IRG levels also increased following PDL, particularly in cases administered with pancreatic enzymes. IRI levels were higher at the first week of PDL than before PDL, but tended to decrease thereafter. It is assumed that gastric hypersecretion after PDL would have complicated relations with IRG, gastric inhibitory polypeptide (GIP) as well as with antral gastrin.

Animals↗
PubMed1981

A role of H+ flux in active Ca2+ transport into sarcoplasmic reticulum vesicles. I. Effect of an artificially imposed H+ gradient on Ca2+ uptake.

To ascertain the function of H+ flux in active Ca2+ transport into sarcoplasmic reticulum vesicles, the effect of pH gradient on Ca2+ transport was examined. A transient H+ gradient (inside-acidic) was imposed on K+-loaded sarcoplasmic reticulum vesicles with the aid of K+-H+ exchange driven by nigericin. This proton gradient was dissipated rapidly and concomitantly with ATP-driven Ca2+ transport. Under these conditions, the initial rate of the Ca2+ uptake was increased about 1.5-fold. The stimulation of Ca2+ uptake was completely lost when the pH gradient was cancelled with an uncoupler plus membrane permeable cation before Ca2+ uptake. These results are interpreted in terms of H+ efflux coupled with Ca2+ transport.

Animals↗
PubMed1981

A role of H+ flux in active Ca2+ transport into sarcoplasmic reticulum vesicles. II. H+ ejection during Ca2+ uptake.

Proton efflux during Ca2+ transport into sarcoplasmic reticulum vesicles was examined. Although a rapid H+ ejection was observed during the initial phase of Ca2+ uptake and the amount of the liberated H+ was more than that due to hydrolysis of ATP, generation of a pH difference as a result of the H+ efflux could not be detected by direct pH measurement with a pH meter. Alkalinization of the inside of the vesicles during Ca2+ uptake was more precisely examined by flow dialysis assay and a significant uptake of acetate or salicylate into the vesicles was found, suggesting the generation of a small pH difference across the SR membrane. From these results, it was concluded that counter-transport of H+ was operative in Ca2+ uptake but that only a relatively small pH difference was generated as a result of the H+ efflux. The intrinsic buffering capacity of sarcoplasmic reticulum vesicles was measured and a relatively large value (130 nmol H+/pH unit/mg at pH 6.2) was obtained.

Animals↗
PubMed1981

Enzymohistochemical study on the gestational choriocarcinoma: histochemistry of choriocarcinoma.

Histochemical investigation of Al-p, HSAP, Ac-p, and LDH was performed with tissues of normal chorionic villi, H. mole, invasive mole, and choriocarcinoma with the following conclusions: 1. In the normal villous tissues, Al-p, HSAP, and Ac-p are localized in syncytiotrophoblast, the former two in the rim of the cell, and the latter inside the cytoplasm. LDH displayed higher activity in cytotrophoblast than syncytiotrophoblast, especially in the former of cell column of initial chorionic villi. 2. In H. mole, Al-p, HSAP, and Ac-p are localized in syncytiotrophoblast of cystic epithelium, and in this layer and transitional cells of the chrioblastic part, the former two are localized in the rim of the cell, the latter within the cytoplasm. LDH is localized in cytotrophoblast and the transitional cell of the cystic epithelium and the chorioblastosis. 3. Localization and activities of Al-p, HSAP, Ac-p, and LDH in invasive mole are closely similar to those in H. mole. 4. Localization and activities of Al-p, HSAP, and Ac-p in choriocarcinoma presented various aspects, but more frequently they are localized in syncytiotrophoblasts in the periphery of focus and also partly in cytotrophoblasts and transitional cells. Also localization and activity of LDH showed diversity. However, the activity is stronger in cytotrophoblast. 5. From those findings, choriocarcinoma is hardly comparable with H. mole or invasive mole from an enzymohistochemical viewpoint and is assumed to have specific enzymic deviation invisible in the others and therefore to possess particular characteristics different from those of any other villous tissues.

Acid Phosphatase↗
PubMed1980

Involvement of 17K dalton light chain of smooth muscle myosin in substrate-induced conformational change.

Conformational changes of the region involving 17K dalton light chain (G2) in gizzard myosin induced by ATP and its analogs were studied by a combination of light chain exchange and fluorescence spectroscopy. The cysteinyl residues of myosin light chain mixture, 20K dalton G1 and 17K dalton G2 chain, were labeled with a fluorescent thiol reagent, N-(1-anilionon-aphthyl-4ymaleimide (ANM). Chicken gizzard myosin was incubated with a large excess of the fluorescence labeled exogenous light chains in 2 M urea. After removal of urea and unbound light chains, a strong fluorescent band was observed at the position of the 17K dalton light chain (G2) of myosin on SDS PAGE. There was no difference in enzymatic activity and light chain composition between myosins before and after light chain exchange. The emission spectrum of ANM label in 17K dalton light chain in the bound state in myosin showed a fluorescence enhancement and a blue shift on adding ATP but not ADP. The spectral change disappeared after conversion of ATP to ADP. Various nucleoside triphosphates other than ATP had similar effects on the fluorescence spectrum. The relative effectiveness of most nucleotides on the fluorescence spectral change of ANM in the light chain bound in myosin agreed well with that on tryptophan residues in myosin, except in the case of ADP and CTP. These results suggest that 17K dalton light chain of gizzard myosin is closely related to the ATPase site of myosin.

Adenosine Triphosphate↗
PubMed1980

Fluorometric studies on the light chains of skeletal muscle myosin. III. Effect of Ca2+ on the reactivity of two SH groups of DTNB light chain in myosin and in the isolated state.

We studied the effect of Ca2+ on the reactivities of two SH groups of DTNB light chain (Cys 128 and Cys 157) using a fluorogenic thiol reagent. It was found that a Ca2+-induced change in reactivity occurred only with Cys 128 when the light chain was in an isolated state, whereas it occurred with both Cys 128 and Cys 157 when the light chain was incorporated in myosin. These results indicate that the Ca2+-induced change in the conformation of DTNB light chain in the isolated state was different from that of the light chain in myosin. It may therefore be difficult to relate the Ca2+-induced conformational change observed in the isolated DTNB light chain to the molecular mechanism of myosin-linked Ca2+ regulation.

Amino Acid Sequence↗
PubMed1980

Actin-induced local conformational change in the myosin molecule. III. Reactivity of S2 thiol and DTNB-reactive thiols of porcine cardiac myosin.

The reactivity of thiol groups in cardiac myosin obtained from porcine ventricles was compared with that in rabbit skeletal myosin. 1. The specific thiol group, S2, of cardiac myosin became reactive to N-ethylmaleimide (NEM) upon the addition of Mg2+-ATP or Mg2+-ADP, as in the case of skeletal myosin, although to a lesser degree. Enhancement of the reactivity of S2 resulting from cooperative interaction between F-actin and Mg2+-ATP, but not Mg2+-ADP, which was first found in skeletal myosin, was also observed in cardiac myosin. 2. The total number of 5,5'-dithiobis(2-nitrobenzoate) (DTNB)-reactive thiols decreased in the presence of Mg2+ADP and decreased further in the presence of Mg2+-ATP for both myosins, in contrast to the concomitant increase in the reactivity of S2. The decrement was smaller in cardiac myosin than in skeletal myosin. 3. The DTNB-reactive thiols were classified into three groups with respect to their reactivity. The third or most slowly reacting thiol group, was found to be remarkably susceptible to Ca2+ at physiological concentrations (10(-8)-10(-6) M) in the presence of Mg2+-ADP for cardiac myosin, but in striking contrast, in the presence and relatively long-lived intermediate of myosin ATPase, the structure of which is sensitive to Ca2+, may be different in cardiac and skeletal myosins.

Actins↗
PubMed1980

Thiols of myosin. VI. Effect of ADP on the reactivity of thiol groups other than S2.

Experiments were carried out to explore the location of thiol groups which became less reactive when S2 became more reactive in the presence of ADP. Myosin was first treated with N-ethylmaleimide to block S1 and then treated with a fluorogenic thiol reagent, N-(7-dimethyl-amino-4-methylcoumarinyl) maleimide (DACM), in the presence or absence of ADP. From the distribution of DACM in the two kinds of DACM-treated myosin, it was found that thiol groups of all the light chains and of the 50 K fragment of subfragment-1 heavy chain became less reactive to DACM in the presence of ADP. Since it is known that the ADP binding site and S2 are located in the 26 K and 21 K fragments of subfragment-1 heavy chain, respectively, our results suggest that the 50 K, 26 K, and 21 K fragments of subfragment-1 heavy chain and light chains are closely connected with each other in the subfragment-1.

Adenosine Diphosphate↗
PubMed1980

Two opposite effects of ATP on the chymotryptic cleavages in smooth muscle myosin head. Determination of cleavable points and their characterization.

The locations of ATP-induced structural change in gizzard myosin were examined by analyzing the changes in the chymotryptic fragmentation pattern. From the time course of fragmentation, and by fractionation of the produced fragments and detection of the masked amino terminal fragment, the original positions of the six different fragments in the parent myosin molecule were assigned. A reconstituted model of myosin based on the above assignment showed the presence of three cleavable sites in the heavy chain of myosin. ATP accelerated the cleavage at site 1, 5 K daltons from the masked amino terminus, while it inhibited cleavage at site 2, 71 K daltons from the N terminus. These opposite effects of ATP on sites 1 and 2 were remarkable, but ATP had no significant effect on cleavage at site 3, 100 K daltons from the carboxyl terminus. These results indicate that two distant regions in the myosin head, 66 K daltons apart in the primary sequence, were exposed or buried with the progress of the ATPase reaction. In addition, prolonged chymotryptic digestion failed to produce any subfragment-1, irrespective of the presence or absence of divalent cations in the digestion medium, but produced a protease-resistant and relatively long (100 K daltons) light meromyosin. This suggests a distinctive feature of the neck and hinge regions in gizzard myosin.

Adenosine Triphosphate↗
PubMed1980

Statistical analysis of beta 2-microglobulin levels in sera of lung and GI tract cancer patients.

Two radioimmunoassay methods were used to determine levels of beta 2-microglobulin in sera of lung and GI tract tumor patients (benign and malignant), as well as of normal individuals. Two screening sera panels were provided by the National Cancer Institute for this purpose. Statistical analysis of the results (performed by an independent institution) of the two panels provided discrepant results. This study points to the need of careful evaluation of results obtained by screening for any potential tumor marker.

Adolescent↗
PubMed1980

Fluorescent staining of microfilaments with heavy meromyosin labeled with N-(7-dimethylamino-4-methylcoumarinyl) maleimide.

For fluorescent staining of microfilaments in cells, heavy meromyosin (HMM) or subfragment-1 (S-1) was labeled with a novel thiol-directed fluorescent dye, N-(7-dimethylamino-4-methylcoumarinyl) maleimide (DACM), instead of the usual dyes, such as fluorescein-isothiocyanate (FITC). DACM-labeled HMM or S-1 gave characteristic fluorescence patterns to a variety of cell types similar to those reported with the use of FITC-labeled HMM or S-1 or with immunofluorescence techniques using anti-actin antibody. The fluorescence of DACM was fairly photoresistant as compared with FITC, so that HMM or S-1 required only 1 mol of the dye per myosin head. Consequently, F-actin need not be used to preserve the actin binding activity of the myosin fragments when labeling with the dye.

Animals↗
PubMed1980

New assessment of the completeness of vagotomy and the selection of operation for duodenal ulcer based upon gastric pepsin secretion.

On the basis of the study of gastric pepsin secretion before and after operation for duodenal ulcer, the assessment of the completeness of vagotomy and the selection of operation were attempted. Vagotomy with pyloroplasty that results in a postoperative peak pepsin output (PPO) after insulin stimulation of less than 100 mg tyrosine/hr may well be considered as representing complete vagotomy. In view of the evaluation of ulcer recurrence, this criterion was confirmed to be a more reliable index compared with the criteria based upon gastric acid secretion. Therefore, concerning the selection of operation for duodenal ulcer on the basis of gastric pepsin secretion, we propose the following criteria: Vagotomy with pyloroplasty should be indicated for patients with an insulin-stimulated preoperative PPO less than 500 mg tyrosine/hr; vagotomy with hemigastrectomy for those with 500--1250 mg tyrosine/hr; and distal gastrectomy such as Billroth I operation for those with over 1250 mg tyrosine/hr.

Adult↗
PubMed1980

Gastric pepsin and acid secretion following various operations for gastric and duodenal ulcer.

In 117 cases of gastric and duodenal ulcer subjected to various types of operation, insulin- and histamine-stimulated secretion of gastric pepsin and acid was investigated at follow-up. Secretory responses of gastric pepsin to the stimulation with insulin and histamine were different from those of gastric acid. Insulin was confirmed to have a greater ability than histamine to stimulate gastric pepsin secretion. In the cases of vagotomy with pyloroplasty and those of vagotomy with hemigastrectomy, the average reduction rates of peak pepsin output were 80% and 92%, respectively, after insulin-stimulation, and 52% and 74% after histamine-stimulation. In view of gastric pepsin secretion, pylorus-preserving gastrectomy and segmental gastrectomy are more physiological than distal gastrectomy.

Adult↗
PubMed1980

Study on histogenesis of pelvic endometriosis.

The histogenesis of pelvic endometriosis can not be sufficiently accounted for by a single theory. Thus it may be necessary to pressure plural theories for the explanation of their histogenesis. On collected 253 cases of endometriosis, some clinical and pathological studies were carried out and classified to adenomyosis (A) 37%, ovarian and pelvic endometriosis (O.P) 17%, and others (A+O.P) 45%. Age of the group O.P adenomyosis (A) 37%, ovarian and pelvic endometriosis (O.P) 17%, and others (A+O.P) 45%. Age of the group O.P tended to be younger, as compared with other groups. Pathological study revealed that in group (A+O.P), the lesion tended to be younger, as compared with other groups. Pathological study revealed that in group (A+O.P), the lesion in uterine wall was extensive and deep proliferation in many cases, and it was frequently more at least than group A. Especially, it is necessary to distinguish from each other two different cases which showed endometriosis in the ovary and pelvic peritoneum, that is, to distinguish them by the presence or absence of adenomyosis. In the case of group O.P complicated by A, it is thought highly probable that discrete dissemination may take place from the foci of adenomyosis. In the case of group O.P there may be sufficient room for the application of the Sampson's theory or metaplastic theories. In view of conspicuous trait in the age, however, the possibility of lymphogenous dissemination of endometriosis may be valuable.

Adult↗