"Sand bar" of actinoid and neighboring elements in a chart of nuclides

Inspection of a chart of nuclides reveals a "sand bar" of actinoid and neighboring elements when a suitable half-life level is chosen. A bay of alpha-instability lying between the nuclides of neutron magic number 126 and the beta-stability line in the actinoid group is a characteristic feature in this area. Calculation shows that fairly good agreement is obtained between the measured half-lives and those derived theoretically.

Significance of sustained gastric hypersecretion by the emulsified histamine solution

Experimental production of gastric and duodenal ulcers was investigated in dogs by administration of histamine emulsified in Freund's incomplete adjuvant. Acid secretory responses were also checked. The results are as follows: Intramuscular administration of 10 mg/day of the emulsified histamine solution caused sustained gastric hypersecretion due to gradual liberation of histamine but produced no apparent side effects. However, neither gastric nor duodenal ulcer was observed within 2 months with the dosage of 10 mg/day. These results suggest that intramuscular administration of the dosage of 10 mg/day within 2 months would be a valuable means to elucidate the pathogenesis of ulcer under the sustained gastric hypersecretion.

Multiple forms of human intestinal alkaline phosphatase: chemical and enzymatic properties, and circulating clearances of the fast- and slow-moving enzymes

Two forms of alkaline phosphatase (orthophosphoric monoester phosphohydrolase (alkaline optimum, EC 3.1.3.1) have been purified from human small intestine by column chromatography on DEAE-cellulose and tyraminyl derivative affinity gel, and by preparative disc gel electrophoresis. Intestinal phosphatases were electrophoretically separated into two components, fast- and slow-moving enzymes, with apparent molecular weights of 140000 and 168000 and with subunit weights of 68000 and 80000, respectively. Analyses of carbohydrate and amino acid revealed marked differences in the two enzymes. Enzymatic properties and affinities for an anti-blood group antibody were also found to differ. Papain digestion released a hydrophobic small peptide from the slow-moving enzyme and its enzymatic properties resembled those of the fast-moving enzyme. Circulating clearance (T1/2) of the slow- and fast-moving enzymes from adult intestine was found to be 7.5 h and 1.3 h, respectively; that of fetal intestinal enzyme was 2.8 h. Sialidase, sialidase/beta-galactosidase, or sialidase/beta-galactosidase/N-acetyl-beta-glucosaminidase treatment of the fetal enzyme reduced the value to about 40 min. Further, digestion with alpha-fucosidase, alpha-mannosidase or both restored it to nearly the original level. Organ distribution of injected 125I-labelled enzymes indicates that the desialylated hepatic enzyme was selectively distributed in liver, while the degalactosylated intestinal enzyme was incorporated into liver lymph fluid, and small intestine. These results suggest that the pathway of circulating clearance of alkaline phosphatase has several routes.

The effect of cleavage at site 1 of gizzard HMM in the interaction with skeletal muscle actin

Two different classes of gizzard heavy meromyosins (HMMs) were prepared from phosphorylated myosin by chymotryptic digestion in the presence and absence of ATP and were compared with respect to their actin-activated Mg2+-ATPase reactions. One class of HMM, named HMM(+), had a cleavage at site 1 in the N terminal portion of the heavy chain and the other class of HMM, named HMM(-), had no cleavage at this site. Maximum turnover rate (Vmax) of the skeletal acto-gizzard HMM Mg2+-ATPase reaction was obviously different between HMM(+) and HMM(-). The Vmax value of HMM(+) was 2.5-fold larger than that of HMM(-). On the other hand, the apparent association constants (Ka) of skeletal muscle actin for both HMMs which were deduced from double reciprocal plots (v-1 versus [actin]-1) seemed to be identical. The difference in Vmax value was attributed to the cleavage at site 1 since a following chymotryptic cleavage of HMM(-) at site 1 caused a 2.5-fold increase in the Vmax value. That site 1 in the N terminal portion of the gizzard myosin heavy chain was the key locus for the actin-myosin interaction was shown in addition to our previous finding of the effects of cleavage at site 1 on the ATPase activity and nucleotide binding ability of gizzard HMM (Okamoto, Y. & Sekine, T. (1981) J. Biochem. 90, 833-843; 843-949).

A new fluorometric ultramicro determination of serum cystine aminopeptidase using an aminocoumarine derivative

A rapid and sensitive fluorometric rate assay of serum cystine aminopeptidase is described using a novel fluorogenic substrate, 7-S-benzyl-L-cysteinyl-4-methylcoumarinylamide. The proposed method enabled us to determine cystine aminopeptidase activity in one minute using 10 microliter of serum. The assay was shown to be free from error due to the adsorption of the substrate to serum albumin. The values obtained by this method gave good correlation with those obtained by the conventional method of Watson [6].

N-terminal region of gizzard myosin heavy chain is critical for the ATPase activity

Two different HMM species of gizzard myosin were prepared under conditions such that the phosphorylation of light chain was fully maintained. They were different in the N-terminal structure of the heavy chain but not in the light chain composition. A significant decrease in the Mg2+-ATPase activity was observed in one class of HMM which was proteolytically cleaved intramolecularly at site 1, 5 K daltons from the masked N terminus. Another class of HMM without the cleavage at site 1 showed ATPase activity similar to that of myosin. The decrease in ATPase activity was not caused by denaturation since similar amounts of initial burst of Pi liberation were observed with both HMMs and myosin. Kinetic and substructure analyses of HMM revealed that the activity change depended solely on the cleavage at site 1. The N-terminal region of gizzard myosin heavy chain may thus have an important role in maintaining the active site structure.

Histologic stromal reaction of the host with gestational choriocarcinoma and its relation to clinical stage classification and prognosis

One of the factors determining the prognosis of choriocarcinoma is the stromal reaction of the host. We have been interested in the histologic findings of this reaction, and we studied the relationship between the CPV classification, which had been used in our department, and our clinical stage. There was no relation of stage distribution to CPV classification. For instance, Type C, which has a strong stromal reaction, did not display any parallel relation with stage. When mortality rates and stages are compared, however, it is noteworthy that the mortality rate for Type C cases is small in Stage I and is less than 50% even in Stage III, in which metastasis is considered to be inevitable; thus, more than half of the cases are cured. On the contrary, Types P and C tend to be associated with high mortality rates even in Stages I and II, in which metastasis is not certain.

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.

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.

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.

Light chain phosphorylation alters the N terminal structure of gizzard myosin heavy chain in an ATP dependent manner

It was shown that the heavy chain structure was altered by the phosphorylation of light chain in gizzard myosin. Phosphorylated myosin was compared with unphosphorylated myosin with respect to the chymotryptic fragmentation with or without ATP in the medium. The rise and fall of the fragments were well explained by the reconstitution model for unphosphorylated myosin (Okamoto, Y., et al. (1980) J. Biochem. 88, 361-371). A specific cleavable site in the myosin head was completely abolished by the phosphorylation of light chain. The effect of phosphorylation on the site could be observed in the absence of ATP but not in its presence. These results strongly suggest the possible integrity of the site, 5K daltons apart from the masked N terminus, for the physiological activity of gizzard myosin.

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.

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.

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.

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.

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.

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.