The specific reduction of a and d antigenic determinants after periodate treatment of hepatitis B surface antigen (HBsAg)

HBsAg antigenicity was found to be sensitive to periodate treatment. Antigenic determinants a and d were especially sensitive, losing almost all of their activity, while determinants r and w were found to be quite stable. Also, it is now possible to prepare the monospecific antibodies, anti-r and anti-w, by the use of this new, simpler procedure.

Fluorometric studies on the light chains of skeletal muscle myosin. I. Effects of temperature, ionic strength, divalent metal ions, and nucleotides

Light chains of skeletal muscle myosin were studied through the reactivity of their SH groups with a fluorescent thiol reagent, N-(7-dimethylamino-4-methylcoumarinyl) maleimide (DACM). The experiments were carried out by reacting the reagent with myosin for a short time and measuring the amounts of reacted dye by fluorometry after separating light chains by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The two classes of light chains, alkali light chains and DTNB light chain, were clearly distinguished by their manner of reactivity change, and differences in their environment and in their function were suggested. Although we found that the SH groups of the DTNB light chain were susceptible to very low concentrations of Mg ions (of the order of 10-5 M), we could not observe Ca2+-induced conformational change by our technique. We also estimated the stoichiometry of light chains in skeletal muscle myosin to be 1.37 mol alkali light chain 1, 1.95 mol of DTNB light chain and 0.77 mol of alkali light chain 2 per mole of myosin from the total amounts of our reagent that reacted with each light chain.

Actin-induced local conformational change in the myosin molecule. I. Effect of metal ions and nucleotides on the conformational change around a specific thiol group (S2) of heavy meromyosin

As previously reported when a specific thiol group, S2, of myosin reacts with N-ethylmaleimide (NEM), its Ca2+-ATPase activity is decreased. Therefore, the reactivity of S2 can be estimated by measuring the decrement of the enzymatic activity. Using the change in the reactivity as a structural probe, we investigated whether F-actin affects the conformation around the region containing S2 under physiological conditions (at neutral pH and low ionic strength). 1. Experiments were carried out with heavy meromyosin (HMM), S1 of which had heen blocked with NEM, to observe the reactivity of S2 alone. In the experiments done in the presence of F-actin, the Ca2+-ATPase activity was measured using the heavy meromyosin fraction after actin had been removed by centrifugation and gel filtration. 2. ATP and other nucleotides activated the reactivity of S2 in the presence of Mg2+. On the other hand, F-actin markedly activated the reactivity of S2 which had been increased by ATP, but not by the other nucleotides. 3. The above cooperative action of F-actin with ATP was not observed in the presence of Ca2+ instead of Mg2+, or above 0.2 M KCl. These results suggest that the S2 region of the myosin molecule is a key region in the molecular interaction of the actin myosin-ATP system under physiological conditions.

Effect of exercise on the skeletal myosin of growing rat

In order to study the effect of running on ATPase activity of myofibril and myosin in the hindlimb muscles, male wister rats of the same venter weighing approximately 50 g were housed in individual cages and allowed to run unimpeded on a treadwheel for 25-30 days. The myofibril and myosin prepared from the exercised rats had lower activation energy of ATP hydrolysis reaction and higher specific ATPase activity than those from the control rats. The myosin prepared from the running-group contained a much higher amount of the light chain having a molecular weight of 16,000, characteristic of white skeletal myosin, than that from the control group. These observations suggest that physical training changed the ratio of populations in myosin molecules, for instance, white and red skeletal myosin.

Thiols of myosin. IV. "Abnormal" reactivity of S1 thiol and the conformational changes around S2 thiol

The flexibility of the tertiary structure around the active site of myosin ATPase [EC 3.6.1.3] was studied using the reactivity of two specific thiol groups, S1 and S2, as a structural probe. The following four maleimide derivatives were used as thiol-directed reagents: N-ethylmaleimide (NEM), N-(4-methoxy-2-benzimidazolyl methyl) maleimide (MBM), N-(p-(2-benzimidazolyl)phenyl)maleimide (BIPM) and N-(4-dimethyl-amino-3,5-dinitrophenyl)maleimide (DDPM). 1. All the maleimide derivatives used activated the Ca2+-ATPase activity and inhibited the EDTA-ATPase activity, like NEM, indicating that they modified S1. The rate of modification of S1 by NEM and BIPM increased with increasing pH, while that by DDPM decreased. BIPM simultaneously modified S1 and S2. 2. S1 showed much higher reactivity toward the maleimides, except for BIPM, than did N-acetylcysteine (N-Ac-Cys) a low molecular-weight model compound. The extremely small pKa value of S1, 6.28, accounted for this high reactivity. In addition, the ATP-induced increase in its reactivity inducated that S1 was in a buried state. Kinetic analysis showed that the teritiary structure around S1 at alkaline pH differed from that at acidic pH. 3. The apparent rate constant of S2-modification with NEM was approximately one seven-hundredth and one four-hundredth of those of S1 and N-Ac-Cys, respectively. Fluorimetric studies using BIPM revealed that S2 in the buried state was exposed upon adding ATP; this was compensated by the burying of some other thiol group(s) (Sp). Non-linearity of the Arrhenius plots of the reaction rate of S2 suggested that the S2 region of myosin had different conformations at high and low temperatures, the transition temperature being 10--15degrees. This non-linearity completely disappeared in the presence of Mg2+-ATP. On the other hand, Arrhenius plots for the thiols reactive to BIPM did not show non-linearity in the presence or absence of ATP.

Studies on calcium ion-induced conformation changes in the actin-tropomyosin-troponin system by fluorimetry. III. Changes in the conformation of tropomyosin associated with functional states

The local conformational changes in the tropomyosin molecule under various conditions were studied by means of fluorimetry using SH-directed fluorescent dyes, N-(1-anilinonaphthyl-4)maleimide (ANM) and N-(3-pyrene)maleimide (PRM). 1. The fluorescence intensity, polarization and the emmission maximum of ANM-tropomyosin were found to be susceptible to ionic strength, but in different ways. The changes in these parameters suggest that the fluorescence-labeled sulfhydryl group or groups become more buried in a hydrophobic internal region by salt-induced depolymerization of aggregate and by adding F-actin to tropomyosin. 2. Titration of the labeled tropomyosin with F-actin revealed a cooperative nature in ANM labeling and a simple saturation kinetics in PRM labeling. The dissociation constant of F-actin to PRM-tropomyosin was calculated to be 5.8-10(-6) M. 3. Temperature dependence of the fluorescence polarization showed a thermal transition in the conformation of ANM- or PRM-tropomyosin at around 30 degrees C. Flexibility or segmental motion of the region containing the fluorophore was suppressed significantly on adding troponin and markedly on adding F-actin. 4. Measurements of the quantum yield and polarization of the ANM-tropomyosin-F-actin complex suggested that troponin strengthened the binding between the two proteins and that Ca2+ reversed this effect.

An evaluation of segmental gastrectomy for gastric ulcer: one to ten year follow-up

Of 61 patients with gastric ulcer subjected to an improved technique of segmental gastrectomy, 26 were available for follow-up study for 1 to 10 years; evaluations were made mainly on the postoperative reduction of gastric acid secretion and motor function of the gastric remnant.

RESULTS

(1) x-ray observation revealed the gastric remnant to be larger than usually seen following Billroth I or II gastrectomy, with no dilatation or remarkable deformity; sphincteric function of the pylorus and peristaltic activity of the gastric remnant were satisfactory; (2) gastric emptying was usually complete in 60 to 180 minutes in 73 percent of the patients, similar to control patients; (3) no instance of dumping syndrome was recognized; (4) average rates of postoperative acid reduction were 58.3 percent for maximal acid concentration, 67.1 percent for maximal acid output, and 67.6 percent for peak acid output, indicating the reduction of gastric acid secretion to be fairly satisfactory. In none of the patients available for follow-up was identified a recurrence of ulcer. These follow-up results suggest the use of segmental gastrectomy for gastric ulcer and for other benign lesions in the mid portion of the stomach.

Thiols of myosin. III. Spectrophotometric identification of the amino acid residue of myosin modified by rho-nitrobenzenediazonium fluoroborate

As previously reported, rho-nitrobenzenediazonium fluoroborate strongly inhibits Ca2+- ATPase of myosin [EC 3.6.1.3] without appreciable suppression of its EDTA-K+- ATPase activity, and the presence of ATP in the reaction medium reverses the pattern of alteration in both ATPase activities, i.e., causing selective inhibition of EDTA-K+ -ATPase. Spectrophotometric studies on the azo-coupling products of 17 amino acids and their derivatives revealed that the amino acid residue of myosin modified by the diazonium dye was cysteine in both the presence and absence of ATP. It is also suggested that the number of cysteinyl residues responsible for the activity changes was one mole per mole of myosin subunit.

Clinico-pathological studies of the liver in asymptomatic carriers of Australia antigen

In an attempt to clinico-pathologically examine asymptomatic HBs AG carriers, follow-up studies were made on 57 HBAg-positive blood donors with the S-GPT within normal range and the following conclusions were arrived at: 1) The results of liver function tests made in the present studies revealed the following rates of abnormalities: the S-GPT was abnormal in 14.5% of the subjects, the S-GOT was abnormal in 9%, the serum total bilirubins were abnormal in 12.2%, the serum alkaline phosphatase level was abnormal in 24.5%, the TTT was abnormal in 4.4%, the ZTT was abnormal in 2.2%, the gamma-globulin was abnormal in 21.2%, and the ICG retention was abnormal in 25.6%. It was thus necessary to make a follow-up study of the results of liver function test. 2) Anti-HBs was negative in all subjects, the rate of lymphocytic blastogenesis in the peripheral blood (tested by the addition of PHA) was low in 7 (36.8%) of 19 patients, and the MIF test by the addition of the purified HBs Ag revealed that 17 subjects, excluding one subject with a histologic picture of acute hepatitis, were not susceptible to HBs Ag. It was, therefore, surmised that immunological insufficiency would be involved in the development of asymptomatic carriers. 3) Histologic examinations, made on 20 subjects, revealed A.V.H. in one subject, N.S.R.H. in seven, N.S.R. in ten and fatty liver in two, and further revealed mild, diffuse inflammations in 8 subjects in the first two group (40% in total). Further, pleomorphism was noted in the hepatocytes of 8 (40%) of these 20 subjects, and a study is under way of the significance of the pleomorphism.

Biphasic ATP splitting of myosin at low temperature

Studies were carried out to elucidate the nature of biphasic ATP hydrolysis by myosin at low temperature. 1. The rate of ATP splitting decreased sharply at 3--5 min after initiation of the reaction below a critical temperature (25 degrees and 30 degrees in the presence of Ca-2+ and EDTA, respectively). On the other hand, Mg-2+-ATPase [ED 3.6.1.3] did not exhibit such biphasic kinetics. 2. The Arrhenius plot of the second phase of the reaction after the rate transition gave a straight line whether the temperature of assay was above or below the critical one, giving 5.7 kcal/mole as the activation energy of Da-2+-ATPase showed features similar to those of Ca-2+-ATPase. 3. Michaelis constants for the two phases at 8 degrees were also different. In addition, the first phase of EDTA-ATPase was shown to have two different constants, depending on ATP concentration. 4. The profiles of the dependence of ATPase activity on KCl concentration were essentially the same for both phases, while bending of the time curve was scarecly observed obove pH 8 for Ca-2+-ATPase or at pH 6 for EDTA-ATPase. 5. 2, 4-Dinitrophenol abolished the phase transition for Ca-2+-ATPase and EDTA-ATPase, and heat treatment also minimized the transition for the former.

Pylorus-preserving gastrectomy for gastric ulcer--one- to nine-year follow-up study

Of 100 patients subjected to pylorus-preserving gastrectomy for surgical treatment of gastric ulcer, 60 were available for follow-up for periods of from one to 9 years. Questionnaires and personal interviews of these 60 and additional laboratory examinations of 40 of them showed results tending to favor the procedure as a highly recommendable technique of gastrectomy. Questions about body weight gain, return to preoperative occupation, and satisfaction with the operation all were answered favorably. In the follow-up laboratory examinations, reduction rates of 57.2 percent for maximal acid concentration, 81.6 percent for maximal acid output, and 70.8 percent for peak acid output. Sphincteric function was generally well preserved on the pyloric ring. Gastric emptying times, ranging from 30 to 180 minutes in 79 percent of the cases, were nearly compatible with the control figures. The results of fat and protein absorption tests performed on some of these patients showed their rates to be within normal ranges. No instances of dumping syndrome, recurrence of ulcer, or other significant postgastrectomy sequelae were recognized. The results indicate pylorus-preserving gastrectomy to be preferable for the surgical treatment of gastric ulcer and other benign lesions of the stomach.