Salivary secretion elicited by taste stimulation with umami substances in human adults

Salivary secretion from the parotid gland was measured whenumami substances (monosodium L-glutamatc, disodium 5'-inosinateand disodium 5'-guanylate) were applied to the anterior or posteriorparts of the tongue in human adults. The amount of secretioninduced by a low concentration (0.01 M) of umami substanceswas very small and similar to that elicited by 1 M sucrose.Salivation induced by a high concentration (0.1 M) of umamisubstances was about twice that induced by the low concentration,but less than that induced by 0.1 M NaCl. The volume of secretioninduced by a mixture containing the low concentration of bothmonosodium L-glutamate and disodium 5'-inosinate (or disodium5'-guanylate) approximated the arithmetic sum of secretionsinduced by the individual components, whereas a mixture of thehigh concentration of these substances elicited much less salivationthan the sum of secretions for the components. More copiousflow of parotid saliva tended to be induced from stimulatingthe posterior tongue compared to the anterior tongue. The presentresults are discussed in terms of the taste properties of umamisubstances as shown in previous psychophysical and elcctrophysiologicalstudies.     

Structural characterization of pentadentate salen-type Schiff-base complexes of oxovanadium(IV) and their use in sulfide oxidation

Pentadentate Schiff-base complexes of oxovanadium(IV), the ligands of which were derived from salicylaldehyde derivatives with a variety of substituents and two kinds of amines (2,2^′-bis(aminoethyl)amine and 3,3^′-bis(aminopropyl)amine), were prepared, and their coordination geometries in the solid state were determined by X-ray diffraction and IR measurements and those in CH₂Cl₂ by EPR measurements. They were found to retain distorted octahedral coordination in the solid state. They showed the structural change depending on the type of the substituent. The complexes which reacted with tert-butylhydroperoxide converted methyl phenyl sulfide to the corresponding sulfoxide at lower rates of reaction than tridentate N-salicylidene-2-aminoethanolato oxovanadium(IV) ([VO(salae)]) and tetradentate (N,N^′-bis(salicylidene)ethylenediaminato)oxovanadium(IV) ([VO(salen)]).     

Effects of high cell density on growth-associated monoclonal antibody production by hybridoma T0405 cells immobilized in macroporous cellulose carriers

Relationship between monoclonal antibody (MAb) productivity and growth rate, and effects of high cell density on MAb production of hybridoma T0405 cells immobilized in macroporous cellulose carriers were investigated in continuous and batch cultures. The results showing, that the specific MAb production rate increased with increasing specific growth rate in both suspended and immobilized continuous cultures indicate a positively growth-associated relationship between MAb productivity and growth rate. Moreover, the specific production rate was higher in the immobilized cell culture than that in suspended one at all dilution rates. In order to clarify these phenomena, MAb mRNA expression and cell cycle distribution were investigated in batch cultures with immobilized cells and suspended cells. RT-PCR was used for observation of MAb mRNA expression and a two-color bromode-oxyuridine (BrdU)/propidium iodide (PI) flow cytometry method for determination of cell cycle distribution. The results revealed that MAb mRNA expression reached the peak during the exponential growth phase, suggest a positively growth-associated MAb production. And the immobilized cells continued the MAb mRNA expression until dead phase, which was longer than that in suspended cells. The cell cycle distribution patterns were observed almost the same for both immobilized and suspended cells. Such results may imply that a high cell density state has positive influence on the mRNA expression and on growth-associated MAb productivity of T0405 cells.     

Expression of MHC-beta and MCT1 in cardiac muscle after exercise training in myocardial-infarcted rats.

To evaluate the hypothesis that increasing the potential for glycolytic metabolism would benefit the functioning of infarcted myocardium, we investigated whether mild exercise training would increase the activities of oxidative enzymes, expression of carbohydrate-related transport proteins (monocarboxylate transporter MCT1 and glucose transporter GLUT4), and myosin heavy chain (MHC) isoforms. Myocardial infarction (MI) was produced by occluding the proximal left coronary artery in rat hearts for 30 min. After the rats performed 6 wk of run training on a treadmill, the wall of the left ventricle was dissected and divided into the anterior wall (AW; infarcted region) and posterior wall (PW; noninfarcted region). MI impaired citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities in the AW (P < 0.01) but not in the noninfarcted PW. No differences in the expression of MCT1 were found in either tissues of AW and PW after MI, whereas exercise training significantly increased the MCT1 expression in all conditions, except AW in the MI rats. Exercise training resulted in an increased expression of GLUT4 protein in the AW in the sham rats and in the PW in the MI rats. The relative amount of MHC-beta was significantly increased in the AW and PW in MI rats compared with sham rats. However, exercise training resulted in a significant increase of MHC-alpha expression in both AW and PW in both sham and MI rats (P < 0.01). These findings suggest that mild exercise training enhanced the potential for glycolytic metabolism and ATPase activity of the myocardium, even in the MI rats, ensuring a beneficial role in the remodeling of the heart.     

Changes in lamina propria dendritic cells on the oral administration of exogenous protein antigens during weaning

Two critical periods of maximum exposure to antigens occur in young mammals, immediately after birth and at weaning, as a result of colonization by commensal bacteria and the ingestion of new diets. At weaning, active immune responses of antibody production against dietary proteins are known to occur, but simultaneously, oral tolerance is acquired for harmless food proteins. However, regulated mechanisms of the immune system at weaning remain to be elucidated although its immune responses may be somewhat similar to those in adulthood. Considering that tolerogenic antigen-presenting cells (APCs) are likely to be a key factor in the acquisition of oral tolerance, in the present study, we examined the changes of dendritic cells (DCs) in the lamina propria (LP) on exposure to food proteins at weaning. C57BL/6 female mice were weaned at the age of 3 weeks and orally administered 10 mg of ovalbumin (OVA) for ten consecutive days after weaning. The administration led to a decrease in the plasma level of immunoglobulin specific for OVA, suggesting the acquisition of oral tolerance. The uptake of fluorescence-labeled OVA was significantly observed for CD11c⁺LPDCs. When we analyzed the changes of two types of LPDCs, PDCA-1⁺ MHC II⁺ DCs and CD103⁺ MHC II⁺ DCs, ten consecutive gavages of OVA marginally, but not significantly, augmented only the frequency of PDCA-1⁺ MHC II⁺ DCs. Considering that the change of APCs likely appears immediately on the response to antigen intake, we found the statistically significant increase in the frequency of PDCA-1⁺ DCs, but not in that of CD103⁺ DCs, even after two treatments, indicating PDCA-1⁺ DCs to be recruited in the LP within 2 days of exposure to food proteins. These results suggest that the behavior of tolerogenic PDCA-1⁺ DCs may change at weaning with the removal of the immunoprotective components of maternal milk.