Antioxidant Potential of Non-Extractable Fractions of Dried Persimmon (Diospyros kaki Thunb.) in Streptozotocin-Induced Diabetic Rats.

Oxidative stress causes the progression of diabetes and its complications; thus, maintaining the balance between reactive oxygen species produced by hyperglycemia and the antioxidant defense system is important. We herein examined the antioxidant potential of non-extractable fractions of dried persimmon (NEP) against oxidative stress in diabetic rats. Rats with streptozotocin-induced type 1 diabetes (50 mg/kg body weight) were administered NEP for 9 weeks. Antioxidant enzyme activities and concentration of antioxidants in liver tissues were analyzed with a microplate reader. Extensor digitorum longus (EDL) and soleus muscle fibers were stained with succinate dehydrogenase and muscle fiber sizes were measured. The administration of NEP increased the body weight of diabetes rats. Regarding antioxidant activities, the oxygen radical absorbance capacity and superoxide dismutase activity in liver tissues significantly increased. In addition, increases in glutathione peroxidase activity in liver tissues and reductions in the cross-sectional area of EDL muscle fibers were significantly suppressed. In these results, NEP improved the antioxidant defense system in the liver tissues of diabetic rats, in addition to attenuating of muscle fibers atrophy against oxidative damage induced by hyperglycemia.

Persimmon-derived tannin has bacteriostatic and anti-inflammatory activity in a murine model of Mycobacterium avium complex (MAC) disease.

Nontuberculous mycobacteria (NTM), including Mycobacterium avium complex (MAC), cause opportunistic chronic pulmonary infections. Notably, MAC susceptibility is regulated by various factors, including the host immune system. Persimmon (Ebenaceae Diospyros kaki Thunb.) tannin is a condensed tannin composed of a polymer of catechin groups. It is well known that condensed tannins have high antioxidant activity and bacteriostatic properties. However, it is hypothesized that condensed tannins might need to be digested and/or fermented into smaller molecules in vivo prior to being absorbed into the body to perform beneficial functions. In this study, we evaluated the effects of soluble persimmon-derived tannins on opportunistic MAC disease. Soluble tannins were hydrolyzed and evaluated by the oxygen radical absorbance capacity (ORAC) method. The ORAC value of soluble tannin hydrolysate was approximately five times greater than that of soluble tannin powder. In addition, soluble tannin hydrolysate exhibited high bacteriostatic activity against MAC in vitro. Furthermore, in an in vivo study, MAC infected mice fed a soluble tannin-containing diet showed significantly higher anti-bacterial activity against MAC and less pulmonary granuloma formation compared with those fed a control diet. Tumor necrosis factor α and inducible nitric oxide synthase levels were significantly lower in lungs of the soluble tannin diet group compared with the control diet group. Moreover, proinflammatory cytokines induced by MAC stimulation of bone marrow-derived macrophages were significantly decreased by addition of soluble tannin hydrolysate. These data suggest that soluble tannin from persimmons might attenuate the pathogenesis of pulmonary NTM infection.

Transient suppression of IgG1 with IL-6 over-expression in immunized TCR-transgenic mice.

Helper T cell-derived cytokines play a pivotal role in the production of antigen-specific IgG antibody by B cells. In order to examine the in vivo effect of massive activation of helper T cells on the production of specific antibodies, ovalbumin (OVA)-specific TCR transgenic mice (OVA23-3) were immunized with OVA and serum levels of antigen-specific antibodies were measured. As a result, a great enhancement of antigen-specific IgM secretion and delay of IgG secretion were observed while the T cells produced sufficient Th2 cytokines. Immediately after OVA-immunization, marked increase of serum IL-6 was noted, which was followed by a transient increase of antibody forming cells. Both in vivo and in vitro experiments demonstrated that excess amount of IL-6 enhanced IgM production by activated B cells while suppressing IgG production. These results suggest that overproduction of IL-6 in the early stages of the primary immunization promotes development of IgM producing cells and causes the delay of IgG1 secretion.

The in vivo development of human T cells from CD34(+) cells in the murine thymic environment.

There is increasing evidence that human hematopoietic stem cells can develop into lymphocytes expressing T cell surface markers in the organ culture of murine embryonic thymic lobes. If human T cells with functional maturity are inducible from human stem cells in the mouse, it may be a useful model to investigate human T cell development and the human immune response in vivo. To approach this, we produced a hybrid cluster of murine fetal thymic epithelial cells and human cord blood-derived CD34(+) cells (hu/m cluster) using reaggregate thymic organ culture, and subsequently implanted it under the kidney capsule of NOD/SCID mice. The implanted hu/m cluster grew in volume under the kidney capsule and contained increased numbers of CD4(+)CD8(+)cells as well as CD4 or CD8 single-positive cells with low CD1a expression. These lymphocytes were also shown to possess activity for producing IL-2 and IL-4. Characteristics similar to human T cells also developed in the thymus of newly established mice lacking NK activity from NOD/SCID mice. These results indicate that functionally mature T cells can develop in vivo from human hematopoietic progenitors in the murine environment composed of thymic epithelial cells.

Identification of a novel protein p59(scr), which is expressed at specific stages of mouse spermatogenesis.

A novel cDNA-encoding polypeptide of 545 amino acid residues was identified from a mouse testis cDNA library. The transcript of this gene, p59(scr), was predominantly expressed in the testis and was developmentally regulated during spermatogenesis. The encoded protein was expressed in spermatocytes and round spermatids within seminiferous tubules of the adult testis. Using an adult-mouse model of experimental unilateral cryptorchidism, it was observed that the expression of the p59(scr) mRNA was reduced in the cryptorchid testes in association with destruction of spermatogenesis. In vitro heat stress experiment further demonstrated that p59(scr) mRNA was more sensitive to heat stress than the other mRNA species, such as germ-cell-specific meiosis-activating kinase (mak) gene and a housekeeping beta-actin gene. Our results suggest that this novel p59(scr) gene is involved in spermatogenesis and may play an important role in development of testicular germ cells.