[The effects of social support reciprocity on mental and physical health of young adults]

The present study examined the effects that reciprocity of social support has on mental and physical health of young adults from the viewpoint that an individual is both an active and passive support provider as well as receiver. The questionnaire, completed by 505 young adults, included items that measured four kinds of support: requested by and provided to others, and requested and received by them. It also asked about the affects associated with support relationships, in addition to the level of adjustment and mental and physical health. Correlational analyses showed that young adults felt their support relationships were fairly reciprocal. ANOVA and multiple regression indicated that lack of reciprocity was in general associated with negative affects and poor health. Providing more support than receiving lead to dissatisfaction, and receiving more than providing to a feeling of indebtedness. Finally, the data supported the prediction that there was a path from support equity to affective state to mental and physical health.

Differential scanning calorimetric studies on the domain structure of Aspergillus glucoamylase

Thermal unfolding of two forms of Aspergillus niger glucoamylase was observed by adiabatic differential scanning calorimetry (DSC) at pH 7. The DSC traces of the larger form of the enzyme, G1, and the shorter form which lacks the C-terminal starch-binding domain of G1, G2, could be resolved by assuming two-state unfolding of five and four independent components, respectively. The thermal unfolding of the starch-binding domain was found to be reversible, but that of the catalytic domain was irreversible. The DSC observation of G1 and G2 in the presence of beta-cyclodextrin or 1-deoxynojirimycin showed that there was no domain interaction between the starch-binding domain and catalytic domain.

Structure of leadership among preschool children

The purpose of the present study was to examine the structure of leadership among preschool children. Leadership behaviors of 18 five-year-old Japanese children were observed during free play and scored on the basis of a 15-item leadership scale. A factor analysis of the items indicated two factors: facilitation of play and consideration-evaluation of playmates. Children who had a central role in group play showed more leadership behaviors on the consideration-evaluation of playmates dimension than those on the periphery. For the dimension of facilitation of play, however, no significant difference was seen between the two groups.

Salt-induced formation of the molten globule state of cytochrome c studied by isothermal titration calorimetry

Although the molten globule state has been proposed as a major intermediate of protein folding, it has proven difficult to obtain thermodynamic data characterizing this state. To explore another approach for characterizing the molten globule state, salt-induced formation of the molten globule state of horse cytochrome c at pH 1.8 was studied by isothermal titration calorimetry. By titrating the acid-unfolded cytochrome c with sodium perchlorate, an exothermic reaction was observed. The titration curve obtained from the heat was cooperative and agreed well with the conformational transition curve measured by CD at 222 nm. This result indicated that the salt-induced conformation change is well approximated by a two-state transition between the acid-unfolded and molten globule states. The heat for formation of the molten globule state estimated by isothermal titration calorimetry was consistent with the enthalpy change for unfolding of the sodium perchlorate-stabilized molten globule state at pH 1.8, which was measured by differential scanning calorimetry and CD. These results indicate that the heat of titration largely reflects the enthalpy change of the conformational transition. From these results, we consider that isothermal titration calorimetry will become a useful approach for investigating the molten globule state.

Interaction between pullulanase from Klebsiella pneumoniae and cyclodextrins

The interaction between pullulanase from Klebsiella pneumoniae and alpha-, beta-, and gamma-cyclodextrins and 6-O-alpha-glucosyl-alpha-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin was examined by means of inhibition studies of the enzyme activity, UV difference spectroscopy, and flow calorimetry. All the above cyclodextrins were found to be competitive inhibitors, but beta-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin showed strong inhibition, the inhibitor constants being two orders of magnitude less than those of alpha- and gamma-cyclodextrins. The difference spectra of beta-cyclodextrin were slightly but significantly different from those of the other cyclodextrins, showing blue shift of a few nanometers. Moreover, only beta-cyclodextrin has a positive entropy change upon binding with the enzyme; all the other cyclodextrins have negative values. These results show that the binding mode of beta-cyclodextrin is subtly different from those of alpha- and gamma-cyclodextrins.

Evaluation of left-sided valvular regurgitation in healthy, hypertensive and myocardial infarction subjects by Doppler echocardiography

Doppler echocardiography has become a very useful and widely employed imaging technique for evaluating valvular regurgitation, and has thus lead to the discovery of regurgitation in unexpected subjects. In this study, we examined left-sided valvular regurgitation in 31 healthy subjects, 35 patients with hypertension and 43 patients with old myocardial infarction by Doppler echocardiography. Aortic regurgitation was found in 3% of healthy subjects, 8% of hypertensive patients and 5% of patients with myocardial infarction. Mitral regurgitation was found in 35% of healthy subjects, 69% of hypertensive patients and 84% of patients with myocardial infarction. The pathogenesis of mitral regurgitation in hypertension is considered to be the impairment of the mitral leaflets, since neither anatomical nor functional abnormalities were found in the subvalvular mitral apparatus. Left ventricular dilatation and asynergy near the papillary muscles were related to the pathogenesis of mitral regurgitation in myocardial infarction. Mitral regurgitation in healthy subjects and hypertensive patients was mild and resistant to afterload stress, suggesting that it was less pathological. On the other hand, mitral regurgitation in myocardial infarction was easily worsened by afterload stress. Doppler echocardiography has thus provided us with new insights into valvular regurgitation in healthy subjects and patients without rheumatic valvular disease.

[An autopsy study of immunoblastic lymphadenopathy (IBL)-like T-cell lymphoma in a patient previously treated with chemotherapy in colon cancer]

A 77-year-old man was admitted to our hospital, due to systemic lymph node swelling. Nine months before his admission, he had been given a right hemicolonectomy for a colon cancer, that had been followed by chemotherapy (MMC and Tegafur). Laboratory testing revealed these findings: RBC 217 x 10(4)/mm3, Hb 8.3 g/dl, haptoglobin less than 10 mg/dl, positive Coombs test, cold hemagglutinin titer, 1:512, and polyclonal hyper r-globulinemia. A biopsy of a lymph node specimen exhibited the histological appearance of an IBL-like T-cell lymphoma described by Shimoyama et al. Although treatment with prednisolone was started for autoimmune hemolytic anemia, the patient died of severe anemia two months after the appearance of his lymph node symptoms.

Differential scanning calorimetric study of the thermal unfolding of Taka-amylase A from Aspergillus oryzae

The thermally induced unfolding of Taka-amylase A, isolated from Aspergillus oryzae, was studied by differential scanning calorimetry. The experimental curves of excess apparent specific heat vs. temperature showed a single asymmetric peak. Curve resolution indicated that this asymmetry is due to the two-state unfolding of three domains in the molecule, with dissociation of the single tightly bound Ca2+ ion occurring during the unfolding of the last domain. Further indication of the dissociation of the specifically bound Ca2+ during denaturation is afforded by the fact that the temperature of maximal excess specific heat, tm, increases with increasing protein concentration in the absence of added excess Ca2+ and with increasing Ca2+ concentration in the presence of added Ca2+. Experiments in a variety of buffers with different enthalpies of ionization indicated that 11.8 +/- 1.5 protons are lost from the protein during unfolding at pH 7.0. In apparent contradiction of this result, the value of tm was found to be essentially independent of pH in the range pH 7-8. No explanation of this anomaly is available. The enthalpy of unfolding at pH 7 and 62 degrees C in the absence of added Ca2+, corrected for the change in buffer protonation, is 2250 +/- 40 kJ mol-1 (42.5 J g-1), and the permanent change in apparent heat capacity is 36.4 +/- 4.1 kJ K-1 mol-1 (0.687 J g-1). Both of these quantities are unusually large for a globular protein.

Psychological processes mediating persuasion-inhibiting effect of forewarning in fear-arousing communication

The present study was designed to investigate the mechanism mediating the persuasion-inhibiting effect of a forewarning in a fear-arousing communication. 93 college students were either warned or not warned of the communicator's persuasive and fear-arousing intents. Results showed that the forewarning produced resistance to persuasion and that resistance was mediated directly by counterarguments during the presentation of the communication, and indirectly by psychological reactance in the postwarning, precommunication interval.

Thermodynamics of the binding of Streptomyces subtilisin inhibitor to alpha-chymotrypsin

The binding of Streptomyces subtilisin inhibitor (SSI) to alpha-chymotrypsin (CT) (EC 3.4.21.1) was studied by isothermal and differential scanning calorimetry at pH 7.0. Thermodynamic quantities for the binding of SSI to the enzyme were derived as functions of temperature from binding constants (S. Matsumori, B. Tonomura, and K. Hiromi, private communication) and isothermal calorimetric experiments at 5-30 degrees C. At 25 degrees C, the values are delta G degrees b = -29.9 kJ mol-1, delta Hb = +18.7 (+/- 1.3) kJ mol-1, delta S degrees b = +0.16 kJ K-1 mol-1, and delta C p,b = -1.08 (+/- 0.11) kJ mol-1. The binding of SSI to CT is weak compared with its binding to subtilisin [Uehara, Y., Tonomura, B., & Hiromi, K. (1978) J. Biochem. (Tokyo) 84, 1195-1202; Takahashi, K., & Fukada, H. (1985) Biochemistry 24, 297-300]. This difference is due primarily to a less favorable enthalpy change in the formation of the complex with CT. The hydrophobic effect is presumably the major source of the entropy and heat capacity changes which accompany the binding process. The unfolding temperature of the complex is about 7 degrees C higher than that of the free enzyme. The enthalpy and the heat capacity changes for the unfolding of CT were found to be 814 kJ mol-1 and 17.3 kJ K-1 mol-1 at 49 degrees C. The same quantities for the unfolding of the SSI-CT complex are 1183 kJ mol-1 and 39.2 kJ K-1 mol-1 at 57 degrees C.

Calorimetric studies of the binding of Streptomyces subtilisin inhibitor to subtilisin of Bacillus subtilis strain N'

The binding of Streptomyces subtilisin inhibitor (SSI) to subtilisin of Bacillus subtilis strain N' (subtilisin BPN', EC 3.4.21.14) was studied by isothermal calorimetry at pH 7.0 and at various temperatures ranging from 5 to 30 degrees C. Thermodynamic quantities for the binding reaction were derived as a function of temperature by combining the data reported for the dissociation constant with the present calorimetric results. At 25 degrees C, the values are delta G degrees = -57.9 kJ mol-1, delta H = -19.8 kJ mol-1, delta S degree = 0.13 kJ K-1 mol-1, and delta Cp = -1.02 kJ K-1 mol-1. The entropy and the heat capacity changes are discussed in terms of the contributions from the changes in vibrational modes and in hydrophobic interactions.

Tumor detection with carbon-11-labelled amino acids

A comparative study of tumor detection with ten 11C-labeled amino acids including four newly synthesized amino acids was carried out to find the most valuable 11C-labeled amino acid for the diagnosis of cancer. 11C-L-methionine showed the highest uptake by the experimental rat hepatoma AH109A (2.7% administered dose/g at 20 min, tumor to blood ratio; 11.4). The second highest uptake was of 11C-aminocyclopentane-carboxylic acid (ACPC). The newly synthesized 11C-DL-methyl-ACPC characteristically showed higher accumulation in tumor than in liver and the tumor to liver ratio reached 3.0 at 60 min after injection. It is suggested that 11C-L-methionine and 11C-DL-methyl-ACPC are useful amino acids for the diagnosis of cancer using positron emission tomography.

Thermodynamics of the binding of L-arabinose and of D-galactose to the L-arabinose-binding protein of Escherichia coli

The thermodynamics of the binding of L-arabinose and of D-galactose to the L-arabinose-binding protein of Escherichia coli have been studied by isothermal and scanning calorimetry. The binding reaction with arabinose is characterized by an enthalpy change of -15.3 +/- 0.5 kcal mol-1 at 25 degrees C, and a large decrease in apparent heat capacity, amounting to -0.44 +/- 0.05 kcal K-1 mol-1, which is constant over the temperature range 8 to 30 degrees C. Very similar results were obtained with D-galactose. These calorimetric results have been combined with binding constants determined by equilibrium dialysis (Clark, A. F., Gerken, T. A., and Hogg, R. W. (1982) Biochemistry 21, 2227-2233) to obtain free energy and entropy changes over the range 5 to 30 degrees C, and by extrapolation to 60 degrees C. The protein undergoes reversible unfolding on being heated with an increase in enthalpy at 53.5 degrees C of 151.8 +/- 1.1 kcal mol-1 (169.2 +/- 1.2 kcal mol-1 at 59.0 degrees C) and in apparent heat capacity of 3.16 +/- 0.07 kcal K-1 mol-1. In the presence of arabinose, the unfolding enthalpy is increased to 200.7 +/- 1.8 kcal mol-1 at 59.0 degrees C, the increase being due to the enthalpy of dissociation of the ligand which amounts to 31 kcal mol-1 at the unfolding temperature. The unfolding temperature is increased by the presence of excess arabinose or galactose, an effect which is due solely to displacement by the added ligand of the unfolding-dissociation equilibrium. The thermodynamic data are discussed in connection with the detailed structural information available for this system from x-ray crystallography (Newcomer, M. E., Gilliland, G. L. and Quiocho, F. A. (1981) J. Biol. Chem. 256, 13213-13217, and references cited therein).

Enthalpy and heat capacity changes for the reduction of insulin

The enthalpy changes for the reduction of three disulfide bonds of insulin by dithiothreitol (DTT) were calorimetrically measured at various temperatures ranging from 289 to 308 K. The reduction was performed in three different buffer solutions of pH 9.6, and the observed heat changes were corrected for the ionization heats of the buffer components to obtain the net heats of reduction of insulin with DTT. By subtracting the enthalpy of DTT oxidation reported in the previous paper [Fukada, H., & Takahashi, K. (1980a) J. Biochem. (Tokyo) 87, 1105-1110], we determined the standard enthalpy of reduction of insulin to be delta Hr = 93.4 +/- 7.8 kJ (mol of insulin-1 at 298 K. The heat capacity change with delta Cp,r = 3.2 +/- 0.3 kJ mol-1 K-1. Using the heat of oxidation of the cysteine residue, we estimated the enthalpy change for the conformational transition of insulin induced by the cleavage of three disulfide bonds to be delta H conf = 91 kJ mol-1 at 298 K. The heat capacity change was 2.1 kJ mol-1 K-1. These results imply that the conformational transition taking place during the reduction of three disulfide bonds is thermodynamically of the same nature as the thermal denaturation observed for other globular proteins.

Calorimetric study of the reduction of the disulfide bonds in insulin

Calorimetric measurement was made on the reduction of the three disulfide bonds of insulin by dithiothreitol (DTT). The reaction was performed at 298 K in three different buffer solutions of pH 9.6. The observed heat changes were corrected for the enthalpy of proton release from the buffer components and the net heat of reaction of insulin with DTT was determined to be delta H0 = 51.5 +/- 1.4 kJ(mol insulin)-1. By subtracting the enthalpy of DTT oxidation (Fukada, H. & Takahashi, K. (1980) J. Biochem. 87, 1105--1110), the standard enthalpy of reduction of insulin was found to be delta H = 78.8 +/- 7.9 kJ(mol insulin)-1. Using the enthalpy change for reduction of random-coil proteins by dithioerythritol (Johnson, R.E., Adams, P., & Rupley, J.A. (1978) Biochemistry 17, 1479-1484), the enthalpy change associated with the conformational change of insulin alone was evaluated to be delta H = 74 +/- 2 kJ(mol insulin)-1 (or 13 J(g protein)-1, a value very similar to that observed for the denaturation of other globular proteins.

Calorimetric study of the oxidation of dithiothreitol

The enthalpy changes of the eoxidation of dithiothreitol (DTT) by ferricyanide was measured calorimetrically in the pH range of 6 to 13 in various buffer solutions at 298 K. By combining the results of potentiometric titrations with the pH dependence of the observed enthalpy changes, the enthalpy changes of DTT oxidation and of the ionization of DTT sulfhydryls were evaluated. The enthalpy changes of oxidation of the non-ionized and the fully ionized DTT were found to be delta HDTT (non-ionized) = 32 +/- 3 kJ mol-1 and delta HDTT (fully ionized) = -38 +/- 3 kJ mol-1, respectively. The enthalpy changes of the first and the second ionizations of DTT sulfhydryls were found to be delta H1 = 48 +/- 2 kJ mol-1 and delta H2 = 21 +/- 3 kJ mol-1, respectively.