Tritiated thymidine autoradiographic study on the origin and renewal of argentaffin cells in the pyloric gland of hamsters

Summary The origin and renewal of the argentaffin cells in the pyloric glands of hamsters were studied by flash, cumulative and pulse labelling autoradiography with ³H-thymidine. The argentaffin cells were identified by the Diazo Method using Fast Red B Salt.By flash labelling autoradiography, it was shown that the argentaffin cells located from the middle to the lower level of the pyloric mucosa were not labelled with ³H-thymidine, indicating that this cell type has no proliferative activity. On the 10th and the 20th day of cumulative labelling, 31% and 63% of the argentaffin cells in the gland were found to be labelled, respectively. The labelled argentaffin cells were concentrated in the upper part of the gland (around the region of the isthmus), and no label was found over nuclei of the cells at the lowermost level of the gland. These labelled cells were shown to undergo a downward migration in the days following pulse labelling. They were replaced by unlabelled (and weakly or very weakly labelled) cells which arose at the region of the isthmus. The argentaffin cells in the pyloric gland are thought to arise from epithelial precursor cells at the region of the isthmus.The labelled argentaffin cells in the gland were found to decrease in number almost exponentially after pulse labelling. This indicates that the life span of argentaffin cells is not fixed, but their renewal conforms to the random loss system. The half time of turnover of this cell population was 15 days on average.Supported by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, Japan     

Antifungal activity of ajoene derived from garlic.

The antifungal activity of six fractions derived from garlic was investigated in an in vitro system. Ajoene had the strongest activity in these fractions. The growth of both Aspergillus niger and Candida albicans was inhibited by ajoene at less than 20 micrograms/ml.     

Purification and properties of two multiple forms of dihydrodiol dehydrogenase from guinea-pig testis

NADP+-dependent dihydrodiol dehydrogenase (trans-1,2-dihydrobenzene-1,2-diol: NADP+ oxidoreductase, EC 1.3.1.20) activity in the cytosol of guinea-pig testis was separated into two major and two minor peaks by Q-Sepharose chromatography; one minor form was immunologically cross-reacted with hepatic aldehyde reductase. The two major enzyme forms were purified to homogeneity. One form, which had the highest amount in the tissue, was a monomeric protein with a molecular weight of 32,000 and isoelectric point of 4.2, showed strict specificity for benzene dihydrodiol and NADP+, and reduced pyridine aldehydes, glyceraldehyde and diacetyl at low rates. Another form, with a molecular weight of 36,000 and isoelectric point of 5.0, oxidized n-butanol, glycerol and sorbitol as well as benzene dihydrodiol in the presence of NADP+ or NAD+, and exhibited much higher reductase activity towards various aldehydes, aldoses and diacetyl. The pI 5.0 form was more sensitive to inhibition by sorbinil and p-chloromercuriphenyl sulfonate than the pI 4.2 form and was activated by sulfate ion. The two enzymes did not catalyze the oxidation of hydroxysteroids and xenobiotic alicyclic alcohols and were immunologically different from hepatic 17 beta-hydroxysteroid-dihydrodiol dehydrogenase. The results indicate that guinea-pig testis contains at least two dihydrodiol dehydrogenases distinct from the hepatic enzymes, one of which, the pI 5.0 enzyme form, may be identical to aldose reductase.     

A new method for finite element simulation of orthodontic appliance-teeth-periodontium-alveolus system

This paper describes a new simulation method to analyze the initial behavior of the total system comprising orthodontic appliance, teeth, and their supporting structures. It is based on a finite element method which additionally takes account of a rotational degree of freedom. Beam and rod elements are used for finite element idealization of orthodontic appliance. Through spring elements it is connected with the teeth supported by the alveolar structures. The technique of 'initial strain' is introduced so as to analyze the effects of a gable bend and activation on the force system which is delivered by the orthodontic appliance. As compared with the photoelastic technique hitherto used, this method serves to investigate systematically and quantitatively the initial aspect of orthodontic tooth movement.     

Immunohistochemical demonstration of serotonergic and peptidergic nerve fibers in the subcommissural organ of the dog

Summary The distributional patterns of serotonin-, luteinizing hormone-releasing hormone (LHRH)-, oxytocin (OXT)- and vasopressin (VP)-immunoreactive nerve fibers were studied in the subcommissural organ (SCO) of the dog by use of the peroxidase-antiperoxidase technique.Abundant serotonergic and moderate numbers of peptidergic nerve fibers running toward the ventricular surface were observed among the cylindrical ependymal cells in the SCO of the dog. Concerning the distributional density of the peptidergic nerve fibers, VP-immunoreactive fibers displayed the highest and LHRH-immunoreactive fibers the lowest values. Most serotonergic and peptidergic fibers returned to the basal portion of the SCO after forming loops immediately beneath the ventricular surface of the ependymal layer. Serotonin-immunoreactive fibers often established a perivascular plexus around the blood vessels in the SCO.At the electron-microscopic level, after use of antiserum to serotonin dark immunoprecipitate was observed in large granular vesicles and the matrix surrounding small and large, clear vesicles and mitochondria; VP immunoreactivity was localized in the large granular vesicles.Serotonergic nerve fibers could be detected in the SCO of the newborn dog. Although the distributional density was in principle not different from that in the adult animal, individual fibers showed immature features such as growth cones and insufficiently swollen varicosities. After penetrating into the ventricle, in the newborn dog, a few serotonin-immunoreactive fibers ran for a relatively long distance on the ependymal surface.     

Preresonance Raman studies of poly(L-lysine), poly(L-glutamic acid), and deuterated N-methylacetamides

The Raman spectra of poly(L -lysine) with various structures, ionized poly(L -glutamic acid), and deuterated N-methylacetamides have been observed using visible and the 257.3-nm laser lines as the light source. Most of the Raman bands with significantly enhanced intensities in the uv-excited spectra of the polymers have been assigned to the vibrations associated with the C?O and C–N stretching modes, the amide I, II, III, I′, II′, and III′, with reference to the results obtained for simple amide molecules including the deuterated N-methylacetamides. Several amide frequencies have been newly identified and the structures of the polymers have been discussed through the comparison of the Raman and ir amide frequencies.     

Light- and diffusion-potential-induced shift of carotenoid spectrum in reconstituted vesicles of Rhodopseudomonas sphaeroides

Proteoliposomes were reconstituted from detergent-solubilized pigment · protein complexes of chromatophores of Rhodopseudomonas sphaeroides and soybean phospholipids. The reconstituted vesicles showed a photooxidation of reaction center bacteriochlorophyll and a light-induced spectral shift of carotenoid to longer wavelengths. The red shift similar to that in intact cells or chromatophores, indicates the generation of local fields in the membrane of proteoliposomes. When inside-positive membrane potential was induced by adding valinomycin and potassium salt, a shift of carotenoid spectrum to shorter wavelengths was observed. Therefore, the reconstituted vesicles, at least in the major part of population, produced the light-induced local field in the same direction as in intact cells, which is inside negative. Sidedness of the membrane structure and the direction of electric field formation in reconstituted vesicles were opposite to those in chromatophores (inside-out vesicles).     

Effect of surface potential on the intramembrane electrical field measured with carotenoid spectral shift in chromatophores from Rhodopseudomonas sphaeroides

Changes in the surface potential, the electrical potential difference between the membrane surface and the bulk aqueous phase were measured with the carotenoid spectral shift which indicates the change of electrical field in the membrane. Chromatophores were prepared from a non-sulfur purple bacterium, Rhodopseudomonas sphaeroides, in a low-salt buffer. Surface potential was changed by addition of salt or by pH jump as predicted by the Gouy-Chapman diffuse double layer theory.When a salt was added at neutral pH, the shift of carotenoid spectrum to shorter wavelength, corresponding to an increase in electrical potential at the outside surface, was observed. The salts of divalent cations (MgSO₄, MgCl₂, CaCl₂) were effective at concentrations lower than those of monovalent cation salts (NaCl, KCl, Na₂SO₄) by a factor of about 50. Among the salts of monoor divalent cation used, little ionic species-dependent difference was observed in the low-concentration range except that due to the valence of cations. The pH dependence of the salt-induced carotenoid change was explained in terms of the change in surface charge density, which was about 0 at pH 5–5.5 and had negative values at higher pH values. The dependence of the pH jump-induced absorbance change on the salt concentration was also consistent with the change in the charge density. The surface potential change by the salt addition, which was calibrated by H⁺ diffusion potential, was about 90 mV at the maximum. From the difference between the effective concentrations with salts of mono- and divalent cations at pH 7.8, the surface charge density of (?1.9 ± 0.5) · 10^?3 elementary charge per Ų, and the surface potential of about ?100 mV in the presence of about 0.1 mM divalent cation or 5 mM monovalent cation were calculated.