Byung Tae Choi

Seasonal Variations in Integumental Glycoconjugates of Rana rugosa

Although environmental conditions can influence the expression of glycoconjugates (GCs) in the epidermis and cutaneous gland of amphibians, seasonal features regarding GCs in frogs have rarely been studied. In the present study, we report the seasonal variations of the integumental GCs in Rana rugosa.

Inhibitory effects of aqueous extracts from nardostachys Chinensis on α‐melanocyte stimulating hormone‐induced melanogenesis in B16F10 cells

Abstract For the purpose of the development of skin‐whitening or therapeutic agents against hyperpigmentation, aqueous extract from Nardostachys chinensis (AENC) was evaluated for melanogenesis inhibitory activity in B16F10 melanoma cell. The treatment with AENC at the 0.2, 0.5 and 1.0 mg/ml level significantly inhibits the biosynthesis of melanin compared with untreated control. The tyrosinase activity also significantly decreased in AENC‐treated cells at the 0.2 and 0.5 mg/ml level and inhibitory effects were more efficient than commercial arbutin at 0.1 mg/ml. The Western analyses confirmed the significantly decreased expression of tyrosinase and tyrosinase‐related protein‐2 by AENC treatment. These results indicate that AENC may contribute to the inhibition of melanin biosynthesis through regulating the expression as well as activity of tyrosinase and AENC may be useful as a new candidate in the design of new skin‐whitening or therapeutic agents.

Histochemistry of Mucosubstances on the Pedal Sole of Five Abalone Species

The present study describes histochemical properties of the mucosubstances in the pedal sole of abalone, in relation to two main additional functions known to date. Only neutral mucosubstances were demonstrated in the lateral epithelium of the pedal sole of the abalone, however, two distinct types of cells, one containing neutral and the other containing acidic mucosubstances, were identified in the ventral epithelium. The epithelial mucocytes distributed throughout both epithelial and subepithelial glands located in the ventral subepithelial region showed a mixture of neutral and acidic mucosubstances. However, acidic mucosubstances were found in larger amounts than neutral ones in epithelial mucocytes, and vice versa in subepithelial glands. Among these acidic mucosubstances, sulphated substances were dominant. Lesser amounts of carboxylated substances also occurred together with low levels of neuramic and sialic acid. Collectively, the notable morphological differences between abalone and other gastrop...

Changes of Glycosylation Pattern in Aging Rat Kidneys as Revealed with Lectin Conjugates

The changes of glycoconjuagates (GCs) in rat kidney due to maturation were studied from samples of fetal and postnatal kidneys by lectin histochemistry. Rat kidneys of perinatal ages and adults were fixed in 4% paraformaldehyde and were stained with nine kinds of biotinylated lectins. The immature forms of the renal developmental stage such as vesicles and ureteric bud were observed in the cortex as late as day 14 of postnatal life, but the histological appearance of the weaning kidney was similar to that observed in adults. As for histochemical properties of GCs in the glomeruli, Con A affinity tended to increase with aging, but both RCA-1 and LCA affinities showed a transient increase in immature glomeruli of neonatal rats. DBA affinity with SBA, PNA, BSL-1 and RCA-1, additional Con A one in proximal tubule, were increased in both proximal and distal tubules according to maturation. In contrast to this, transient intensive LCA affinity were demonstrated in immature proximal and distal tubule of neonatal rats. In the collecting tubules, DBA, SBA, PNA and sWGA affinities tended to increase according to maturation, but transient increase for BSL-1, RCA-1 and LCA affinities were detected in neonatal rats. The present results suggest that the mature glycosylation pattern of the kidney undergoes profound changes during maturation and is probably associated with functional maturation of the kidney.

Blood and serum analyses of cold‐exposed chipmunks

To understand the adaptational strategy of Korean chipmunks (Tamias sibiricus) to cold temperature, blood and serum properties, and thyroid gland activity of cold‐exposed chipmunks were examined. The number of erythrocytes and hemoglobin concentration increased, but platelets decreased in cold‐exposed chipmunks compared with warm chipmunks. Serum total protein levels increased at early phase of cold‐exposure, and decreased thereafter. Plasma glucose levels showed a transitory increase in cold temperature. Although there was significant decrease in serum total thyroxine level in cold‐exposed chipmunks, serum total triiodothyronine level changed little. Histological analysis of thyroid glands demonstrated decreased thyroid activity, suggesting that differences in the blood and serum properties between the warm and cold‐exposed chipmunks may be due to the different metabolic strategy associated with cold temperature.