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Summary Nerium indicum is an India-Pakistan-originated shrub belonging to the oleander family. The ingestion of leaves of N. indicum before a meal is known to effect the lowering of postprandial glucose levels in Type II diabetic patients and this plant is now used as a folk remedy for Type II diabetes in some regions of Pakistan. In the present study, the hot-water extract of N. indicum leaves was found to reduce the postprandial rise in the blood glucose when maltose or sucrose was loaded in rats. It was also found that the extract strongly inhibited ␣ -glucosidase, suggesting that the suppression of the postprandial rise in the blood glucose is due to the occurrence of some inhibitors of ␣ -glucosidase in the leaves. We, therefore, tried to isolate the active principles from the leaf extract, using ␣ -glucosidase-inhibitory activity as the index. Employing Sephadex G-15, silica gel and reversed-phase HPLC, we isolated two active compounds. The UV, mass and NMR spectrometric analyses established that the chemical structures of these compounds are 3-O -caffeoylquinic acid (chlorogenic acid) and its structural isomer, 5-O -caffeoylquinic acid. Both compounds were shown to inhibit ␣ -glucosidases in a non-competitive manner. The authentic chlorogenic acid was found to suppress the postprandial rise in the blood glucose in rats and also inhibited the absorption of the glucose moiety from maltose and glucose in the everted gut sac system prepared from rat intestine. These results demonstrate that chlorogenic acid is one of the major anti-hyperglycemic principles present in the leaves of N. indicum . Furthermore, among polyphenol compounds tested, quercetin and catechins were shown to have strong inhibitory activity against ␣ -glucosidase.

11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) catalyzes the interconversion of cortisone and cortisol within the endoplasmic reticulum. 11β-HSD1 is expressed widely, most notably in the liver, adipose tissue, and central nervous system. It has been studied intensely over the last 10 years because its activity is reported to be increased in visceral adipose tissue of obese people. Epidermal keratinocytes and dermal fibroblasts also express 11β-HSD1. However, the function of the enzymatic activity 11β-HSD1 in skin is not known. We found that 11β-HSD1 was expressed in human and murine epidermis, and this expression increased as keratinocytes differentiate. The expression of 11β-HSD1 by normal human epidermal keratinocytes (NHEKs) was increased by starvation or calcium-induced differentiation in vitro. A selective inhibitor of 11β-HSD1 promoted proliferation of NHEKs and normal human dermal fibroblasts, but did not alter the differentiation of NHEKs. Topical application of selective 11β-HSD1 inhibitor to the dorsal skin of hairless mice caused proliferation of keratinocytes. Taken together, these data suggest that 11β-HSD1 is involved in tissue remodeling of the skin. This hypothesis was further supported by the observation that topical application of the selective 11β-HSD1 inhibitor enhanced cutaneous wound healing in C57BL/6 mice and ob/ob mice. Collectively, we conclude that 11β-HSD1 is negatively regulating the proliferation of keratinocytes and fibroblasts, and cutaneous wound healing. Hence, 11β-HSD1 might maintain skin homeostasis by regulating the proliferation of keratinocytes and dermal fibroblasts. Thus 11β-HSD1 is a novel candidate target for the design of skin disease treatments.

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We have studied the interaction between recombination signal sequences (RSSs) and protein products of the truncated forms of recombination-activating genes (RAG) by gel mobility shift, DNase I footprinting, and methylation interference assays. Methylation interference with dimethyl sulfate demonstrated that binding was blocked by methylation in the nonamer at the second-position G residue in the bottom strand and at the sixthand seventh-position A residues in the top strand. DNase I footprinting experiments demonstrated that RAG1 alone, or even a RAG1 homeodomain peptide, gave footprint patterns very similar to those obtained with the RAG1-RAG2 complex. In the heptamer, partial methylation interference was observed at the sixth-position A residue in the bottom strand. In DNase I footprinting, the heptamer region was weakly protected in the bottom strand by RAG1. The effects of RSS mutations on RAG binding were evaluated by DNA footprinting. Comparison of the RAG-RSS footprint data with the published Hin model confirmed the notion that sequencespecific RSS-RAG interaction takes place primarily between the Hin domain of the RAG1 protein and adjacent major and minor grooves of the nonamer DNA.V(D)J joining is a site-specific recombination process that plays a crucial role in the activation and diversification of antigen receptor genes (44). Joining occurs between two pairs of recombination signal sequences (RSSs): heptamer (CACA GTG) and nonamer (ACAAAAACC) (22,32). Furthermore, the spacer separating the heptamer and the nonamer is either 12 or 23 bp in length, and recombination takes place between two RSSs in which one contains a 12-bp spacer (12-RSS), and the other contains a 23-bp spacer (23-RSS) (8,33,34); this is the so-called 12/23 rule. It has been shown that just two pairs of the heptamer and the nonamer are sufficient for V(D)J type recombination if the 12/23 rule is satisfied (3).V(D)J type recombination consists of two major processes: site-specific cleavage and ligation of cleaved ends. The former process includes specific recognition of the RSS by DNAbinding components of the recombinase, synaptic complex formation between the two RSSs satisfying the 12/23 rule, and site-specific cleavage of RSSs adjacent to the heptamer (29, 37). The latter process is known to be mediated by DNA repair mechanisms, including DNA-dependent protein kinase, (4,17,19), the Ku protein complex (43, 47), XRCC4 (21), and DNA ligases (13,28). During the process of recombination, nucleotide deletion and addition occur at coding ends. Terminal deoxynucleotidyl transferase is responsible for the insertion of non-germ line nucleotides (11, 18).Two recombination-activating genes, rag-1 and rag-2, were isolated by their abilities to activate V(D)J type recombination in a fibroblast cell line (26, 36). It was not clear for many years what roles RAG proteins played in the process of V(D)J recombination. The recent demonstration of in vitro RSS cleavage (45) provided a more convincing argument that the RAG proteins were indeed major com...