Nuclear Symmetry Energy and the Breaking of the Isospin Symmetry: How Do They Reconcile with Each Other?

We analyze and propose a solution to the apparent inconsistency between our current knowledge of the equation of state of asymmetric nuclear matter, the energy of the isobaric analog state (IAS) in a heavy nucleus such as ^{208}Pb, and the isospin symmetry breaking forces in the nuclear medium. This is achieved by performing state-of-the-art Hartree-Fock plus random phase approximation calculations of the IAS that include all isospin symmetry breaking contributions. To this aim, we propose a new effective interaction that is successful in reproducing the IAS excitation energy without compromising other properties of finite nuclei.

Observation of low- and high-energy Gamow-Teller phonon excitations in nuclei.

Gamow-Teller (GT) transitions in atomic nuclei are sensitive to both nuclear shell structure and effective residual interactions. The nuclear GT excitations were studied for the mass number A = 42, 46, 50, and 54 "f-shell" nuclei in ((3)He, t) charge-exchange reactions. In the (42)Ca → (42)Sc reaction, most of the GT strength is concentrated in the lowest excited state at 0.6 MeV, suggesting the existence of a low-energy GT phonon excitation. As A increases, a high-energy GT phonon excitation develops in the 6-11 MeV region. In the (54)Fe → (54)Co reaction, the high-energy GT phonon excitation mainly carries the GT strength. The existence of these two GT phonon excitations are attributed to the 2 fermionic degrees of freedom in nuclei.

Identification of the ß+ isovector spin monopole resonance via the 208Pb and 90Zr(t,3He) reactions at 300 MeV/u.

The double-differential cross sections for the (208)Pb and (90)Zr(t,(3)He) reactions at 300 MeV/u have been measured at the RI Beam Factory at RIKEN. This was the first physics experiment with the SHARAQ magnetic spectrometer. The combined analysis of the present (t,(3)He) data and previous (n,p) data provides the clearest identification for the ß(+) isovector spin monopole resonance both in the (208)Tl and (90)Y nuclei, and puts the observations of this giant resonance on a firm foundation. The measured distributions of the (t,(3)He) monopole cross sections were well reproduced by the distorted-wave Born approximation calculation, where the target transition density was calculated with the self-consistent Hartree-Fock plus random-phase approximation using the T43 Skyrme interaction. A major part of the expected ß(+) isovector spin monopole strength was found in the measured cross section spectra.

Effect of the tensor force on the charge exchange spin-dipole excitations of 208Pb.

The charge exchange spin-dipole (SD) excitations of 208Pb are studied by using a fully self-consistent Skyrme Hartree-Fock plus random phase approximation formalism which includes the tensor interaction. It is found, for the first time, that the tensor correlations have a unique, multipole-dependent effect on the SD excitations; that is, they produce a softening of 1{-} states, but a hardening of 0{-} and 2{-} states. This paves the way to a clear assessment of the strength of the tensor terms. We compare our results with a recent measurement, showing that our choice of tensor terms improves the agreement with experiment. The robustness of our results is supported by the analytic form of the tensor matrix elements.

Survival and axonal regeneration of off-center retinal ganglion cells of adult cats are promoted with an anti-glaucoma drug, nipradilol, but not BDNF and CNTF.

OFF-center retinal ganglion cells (RGCs) occupy a smaller proportion than ON RGCs when RGCs regenerate axons into a transplanted peripheral nerve. We examined whether the regeneration ability of OFF RGCs in adult cats was promoted when the numbers of regenerating RGCs were increased with brain-derived neurotrophic factor (BDNF)+ciliary neurotrophic factor (CNTF)+forskolin (BCF) or 3,4-dihydro-8-(2-hydroxy-3-isopropylamino)-propoxy-3-nitroxy-2H-1-benzopyran (nipradilol), an anti-glaucoma drug. ON or OFF RGCs were morphologically determined on the basis of their dendritic ramification in the inner plexiform layer using computational analysis. In the normal intact retina the ratio of ON and OFF RGCs (ON/OFF ratio) was 1.25 (55%/44%); whereas, it was 2.61 in regenerating RGCs with saline injection (control) 6 weeks after peripheral nerve transplantation. Estimated numbers of regenerating ON and OFF RGCs were 2149 and 895, respectively. An injection of BCF increased only numbers of ON RGCs into 5766 (2.7-fold to control) but not that of OFF RGCs, n=858. Nipradilol increased both estimated numbers of ON (11,518, 5.4-fold to control) and OFF RGCs (7330, 8.2-fold to control). In the retinas with optic nerve (OpN) transection and intravitreal saline-, BCF- or nipradilol-injection, numbers of ON and OFF RGCs surviving axotomy showed similar trend to that in regenerating RGCs. Thus, nipradilol promoted the survival and regeneration abilities of both of ON and OFF RGCs whereas BCF only did the abilities of ON RGCs. The distribution of tropo-myosin-related kinase B, BDNF receptor, was sparser in the outer two thirds of inner plexiform layer. The lower surviving ability of OFF-RGCs may be attributed in part to the distribution.

A tightly regulated expression system in Escherichia coli with SP6 RNA polymerase.

A tightly regulated gene-expression system was developed using SP6 RNA polymerase (RpoSP6). The RpoSp6-encoding gene (rpoSP6) was inserted into a mini-F plasmid (mini-F) and expression was controlled by the lactose promoter (P(lac)) and operator (O(lac)) on the plasmid. Therefore, a controlled expression system for the target genes can easily be constructed in various host strains by co-transformation of the system plasmid pFSP6 with other vector plasmids containing the genes linked to the SP6 promoters (P(SP6)). Using the lac gene linked to P(SP6) as a reporter, we evaluated the regulation of expression in this system in various host strains. Low-level expression of lac was detected in Escherichia coli harboring this expression system when RpoSP6 was uninduced, although very low activities of beta-galactosidase (beta-Gal) were observed which were independent of the presence of pFSP6. This basal level of beta-Gal activity was possibly derived, because the P(SP6) element has very weak activity for E. coli RNA polymerase (Rpo). These results showed that RpoSP6 seemed to be produced at very low levels in uninduced cells. Beta-GAl activity increased about 18-32-fold when the expression of rpoSP6 was induced, as compared with the beta-Gal activity when uninduced. The tight regulation of this system is superior to that of other known systems and it has a considerable advantage for gene expression in E. coli.

Characterization of leukocyte chemotactic activity of bacteriocin from Streptococcus mutans Rm-10.

Bacteriocins have several biological activities in addition to their antibacterial effect. We investigated the chemotactic properties and mode of action of purified streptococcal bacteriocin. Bacteriocin purified from a culture supernatant of Streptococcus mutans (S. mutans) Rm-10 induced chemotaxis of human polymorphonuclear leukocytes and monocytes. Following purification, leukocyte migration appeared in one bacteriocin fraction, and this migration was dependent on the concentration gradient in dilution ranges from 1/960 to 1/15. Chemotactic activity of the bacteriocin was heat labile and trypsin sensitive. Moreover, preincubation of bacteriocin with varying dilutions of its antiserum prepared in rabbits resulted in a significant loss of the chemotactic activity.

Antimicrobial susceptibilities of Eubacterium, Peptostreptococcus, and Bacteroides isolated from root canals of teeth with periapical pathosis.

Eubacterium, Peptostreptococcus, and Bacteroides were isolated in high frequency from root canals with acute periapical inflammation. The antimicrobial susceptibilities of these strains were studied by determining minimum inhibitory concentrations of different agents. Although all three kinds of isolates were susceptible to penicillins, the isolates other than black-pigmented Bacteroides were less susceptible to cephems, tetracyclines, and macrorides with several resistant strains. All strains were uniformly resistant to aminoglycosides. Some differences in susceptibilities were observed among species of Eubacterium and Peptostreptococcus, while penicillins were effective for both species. Black-pigmented Bacteroides showed good susceptibilities to all agents except for aminoglycosides. The susceptibility of Bacteroides gingivalis was superior to that of Bacteroides intermedius. There were many resistant strains in non-black-pigmented but not in black-pigmented Bacteroides isolates. Penicillins were the most effective for Eubacterium, Peptostreptococcus, and Bacteroides, indicating that penicillins are suitable for treatment of root canals with acute apical periodontitis.

Localization and identification of root canal bacteria in clinically asymptomatic periapical pathosis.

Twenty-one teeth with clinically asymptomatic periapical pathosis (class 3) were extracted and the isolation, identification, and localization of bacteria in the root apex were examined. Mixtures involving several bacteria were isolated from more than 60% of the cases. Scanning electron microscopy revealed bacterial masses to be associated with the apical part of the root canal, but not with the area of apical foramen or on the surface of root apex. Our results indicate that the bacteria in class 3 cases may be derived from organisms which colonized before or during endodontic treatment, but not from anachoresis. The bacteria-positive cases of asymptomatic periapical pathosis have the potential to progress to symptomatic periapical pathosis.

Humoral immune responses in experimental gingivitis in rats.

Serum IgG, IgM, and IgA antibody levels to extracts of rat dental plaque and five oral bacteria (Haemophilus actinomycetemcomitans Y-4, Bacteroides gingivalis 381, Bact. intermedius ATCC 25261, Capnocytophaga sp. M-12, Eikenella corrodens ODU) were determined by ELISA. In addition, the presence of rat dental plaque and oral bacterial components in the inflamed gingival tissue was studied using immunofluorescence techniques. Serum and gingival tissue samples were obtained from ODU plaque-susceptible and plaque-resistant rats. In several susceptible rats, IgG, IgM, and IgA antibodies against dental plaque and oral bacteria were detected. There was a correlation between the levels of IgG antibody to dental plaque and pocket probing depth, but not between pocket probing depth and the levels of IgM and IgA. Furthermore, components of rat dental plaque and oral bacteria were detected in the inflamed gingival tissue.

Characterization and mode of action of a purified bacteriocin from the oral bacterium Streptococcus mutans RM-10.

The purified bacteriocin was sensitive to proteolytic enzymes such as trypsin, alpha-chymotrypsin and pronase, but resistant to papain and pepsin. Lowering the pH of the bacteriocin caused precipitation, and the Abs280 of the supernatant reached a minimum at pH 3.6, suggesting that this is the isoelectric point. Such a pH value coincides with minimum bacteriocin activity. The effect of the bacteriocin was bactericidal rather than bacteriolytic and concentration dependent. Treatment of Streptococcus faecalis ODU with Rm-10 bacteriocin led rapidly to the cessation of biosynthesis of macromolecules, DNA, RNA and protein. Electron microscopy showed bacteriocin fibres attached in aggregated bundles to target cells; after ultra-sonication or detergent treatment they were individually attached to the cell surface and, at the same time, the apparent bacteriocin activity had doubled. Bacteriocin activity was not altered by filter-sterilized saliva components. Oral rinsing with Rm-10 bacteriocin reduced the number of viable salivary bacteria after 20 min, suggesting a possible therapeutic use for Rm-10 bacteriocin.

Mucin-producing bronchioloalveolar-cell carcinoma. With special reference to a characteristic structure revealed by phosphotungstic acid-hematoxylin staining.

In four cases of bronchioloalveolar-cell carcinoma of the mucin-producing type, the cells were characterized electron microscopically by cored microvilli seen on the free surface of the tumor cells, structures that corresponded well to the phosphotungstic acid-hematoxylin (PTAH) stained structures seen by light microscopy in histologic specimens. The exfoliative cytology specimens contained corresponding PTAH-stained structures on the cell surfaces, namely, a prominent cell membrane with a "beaded" or "peg-like" configuration and, in places, a "feathery" nature, findings quite dissimilar to the surfaces of other well-differentiated adenocarcinoma cells. The cytologic specimens also exhibited characteristic nuclear indentations and tightly connected cell groupings. These results indicate the existence of a type of bronchioloalveolar-cell carcinoma not derived from type II alveolar epithelial cells or Clara cells.

Flow cytometric analysis of leukocytes and reticulocytes stained with proflavine.

Proflavine, an acridine analog for industrial use, was used to stain blood cells. A drop of blood treated with ethylenediaminetetraacetic acid-2K was mixed with a 0.00001% solution of the dye and observed immediately by fluorescence microscopy with a green filter. Leukocytes, platelets, and reticulocytes were stained but mature red blood cells were not. Chromatin in the nuclei of all leukocytes and nucleoli of lymphocytes and monocytes had greenish-yellow fluorescence, and the kind of cell could be identified by the tone and intensity of this color. Granules in granulocytes were in green. Reticular fine-granular or granulofibrous structures in the reticulocytes were brownish. The proflavine could be used routinely in clinical laboratories because this single stain makes possible simultaneous differentiation of leukocytes and counting of reticulocytes.

[The study on factors affecting cholesterol solubility in bile: relation to biliary proteins including apolipoprotein A-1].

We studied the preferential distribution patterns of cholesterol and proteins to biliary lipid particles isolated from human gallbladder bile by gel permeation chromatography. In addition nucleation times of those bile samples were determined to estimate the metastability of bile cholesterol. Cholesterol dominantly incorporated into a non-micellar fraction in bile from cholesterol gallstone patients with and without preoperative treatment with ursodeoxycholic acid, whereas nucleation time was significantly longer in cholesterol gallstone patients with a preoperative treatment with ursodeoxycholic acid than that of those without any preoperative treatment (p less than 0.01). Furthermore the induced incorporation of apolipoprotein A-1 into a non-micellar fraction was found in bile from cholesterol gallstone patients with ursodeoxycholic acid. These results suggest that stabilizing effects of apolipoprotein A-1 on a non-micellar fraction has been induced by ursodeoxycholic acid treatment resulting in the retardation of cholesterol nucleation in bile.

[A study on the mechanisms whereby apolipoprotein A-1 (apo A-1) inhibits cholesterol crystal nucleation in human gallbladder bile].

The aim of the present study was to determine the mechanisms whereby apo A-1 retards cholesterol crystal nucleation in human gallbladder bile. Ten human gallbladder bile samples were sterilely collected from patients with gallstones at surgery, subsequently applied on gel permeation chromatography to separate various lipid particles. A non-micellar fraction coeluted with apo A-1 was ultrastructurally characterized by transmission electron microscopy (TEM). As results, that fraction containing very little or no apo A-1, 400-600 A in diameter, showed rapid transformation, i.e. rouleau formation, multilamellar formation and consequently microcrystal formation, whereas those rich in apo A-1, 200-400 A in diameter, showed very little transformation for 7 days. Those data indicated that apo A-1 stabilizes non micellar fraction by forming an apo A-1 and lipid complexed particle, resulting in prolonged cholesterol crystal nucleation.

Investigation of irradiation conditions for recurrent breast cancer in JRR-4.

Clinical trials of boron neutron capture therapy (BNCT) for recurrent breast cancers are considered at Japan Research Reactor No. 4 (JRR-4). In this study, the irradiation technique for a total mastectomy patient with recurrent cancer was optimized by dosimetric calculations using JAEA computational dosimetry system (JCDS). The evaluation was performed using an en face technique and a tangents technique with thermal neutron beam mode at JRR-4. The results revealed that equivalent doses of lung, heart, liver and skin were similar in each irradiation technique due to the isotropic scattering of thermal neutrons in the body. On the other hand, the irradiation time with the tangents technique was a few times longer than with the en face technique. We concluded that the en face technique was an optimal irradiation technique for recurrent breast cancers using thermal neutron beam mode in terms of shorter irradiation time and easier patient positioning.