Localization of the dominant non-enzymatic intermolecular cross-linking sites on fibrous collagen.

Previous studies have shown that fibrous collagen undergoes intermolecular cross-linking at multiple sites of the elongated triple-helical regions among adjacent juxtaposed collagen molecules on incubation with a very high concentration of reducing sugar such as 200 mM ribose, and the similarity of the changes in its physicochemical properties to that of senescent collagen aged in vivo has been emphasized. In the present study, however, it was found that when incubated with less than 30 mM ribose, fibrous collagen underwent intermolecular cross-linking primarily between the telopeptide region of a collagen molecule and the triple-helical region of another adjacent collagen molecule, and intermolecular cross-linking between the triple-helical regions of adjacent collagen molecules was very small. Physiological significance of the previous studies thus needs to be reevaluated.

Isolation and characterization of human trophoblast side-population (SP) cells in primary villous cytotrophoblasts and HTR-8/SVneo cell line.

Recently, numerous studies have identified that immature cell populations including stem cells and progenitor cells can be found among "side-population" (SP) cells. Although SP cells isolated from some adult tissues have been reported elsewhere, isolation and characterization of human trophoblast SP remained to be reported. In this study, HTR-8/SVneo cells and human primary villous cytotrophoblasts (vCTBs) were stained with Hoechst 33342 and SP and non-SP (NSP) fractions were isolated using a cell sorter. A small population of SP cells was identified in HTR-8/SVneo cells and in vCTBs. SP cells expressed several vCTB-specific markers and failed to express syncytiotrophoblast (STB) or extravillous cytotrophopblast (EVT)-specific differentiation markers. SP cells formed colonies and proliferated on mouse embryonic fibroblast (MEF) feeder cells or in MEF conditioned medium supplemented with heparin/FGF2, and they also showed long-term repopulating property. SP cells could differentiate into both STB and EVT cell lineages and expressed several differentiation markers. Microarray analysis revealed that IL7R and IL1R2 were exclusively expressed in SP cells and not in NSP cells. vCTB cells sorted as positive for both IL7R and IL1R2 failed to express trophoblast differentiation markers and spontaneously differentiated into both STB and EVT in basal medium. These features shown by the SP cells suggested that IL7R and IL1R2 are available as markers to detect the SP cells and that vCTB progenitor cells and trophoblast stem cells were involved in the SP cell population.

Acid-induced change in ozone-reactive site in indole ring of tryptophan.

It is well established that ozone as well as oxygen activated by tryptophan 2,3-dioxygenase or indoleamine 2,3-dioxygenase cleave the 2,3-C=C bond of the indole ring of tryptophan to produce N-formylkynurenine. In the present study, however, we found that exposure of tryptophan to aqueous ozone at and below pH 4.5 generated a different compound. The compound was identified as kynurenine by high performance liquid chromatography and mass spectrometry. Exposure of N-formylkynurenine to acidic ozone did not generate a significant amount of kynurenine, indicating that the kynurenine was not produced via N-formylkynurenine. Acidic ozone thus appears to cleave the 1, 2-NAC bond in place of the 2,3-C=C bond of the indole ring, followed by liberation of the 2-C atom. The 1,2-NAC bond and 2,3-C=C bond are likely to undergo changes in their nature of bonding on acidification, enabling ozone to react with the former bond but not with the latter bond.

NAT2 and CYP1A2 polymorphisms and lung cancer risk in relation to smoking status.

We investigated the associations between lung cancer and the gene polymorphisms of the drug metabolizing enzymes, containing cytochrome P450 1A1 (CYP1A1), cytochrome P450 1A2 (CYP1A2), glutathione S-transferase class mu (GSTM1), and N-acetyltransferase 2 (NAT2). The study involved 113 lung cancer patients and 121 non-cancer controls divided into never, light and heavy smokers according to pack-years of smoking in Japanese by using PCR-RFLP. For light smokers, the lung cancer risk of NAT2 intermediate-slow was significantly increased [the adjusted odds ratio (OR): 10.9, 95% confidence intervals (95%CI): 1.75-67.5, P-value: 0.010]. Moreover, never smokers having joint genotypes of NAT2 intermediate-slow and CYP1A2*1F A/A was also associated with increased the lung cancer risk (OR: 4.95, 95% CI: 1.19-20.6, P-value: 0.028). We suggested that light smokers with intermediate-slow NAT2 activity were at highest risk for lung cancer and the gene-gene interaction based on intermediate-slow NAT2 activity and high CYP1A2 activity would be increased a lung cancer risk among never smokers.

Variants of calpain-10 gene and its association with type 2 diabetes mellitus in a Chinese population.

Variants of calpain-10 gene (CAPN 10) have recently been reported to be associated with type 2 diabetes (T2DM). Haplotype combination 112/121 defined by three single nucleotide polymorphisms (SNPs) (UCSNP-43, -19 and -63) of CAPN 10 conferred the highest risk for T2DM in Mexican-Americans. In this study, we aim to examine whether these genetic variants contribute to the susceptibility for T2DM in a Chinese population. The frequencies of these three SNPs were determined in 168 patients with T2DM and 104 controls. Distribution of alleles, genotypes and haplotypes at three loci were not significantly different between the two groups. No difference was observed in the 112/121 haplotype combination distribution. However, haplotype combination 112/221 was more prevalent in the control group than in T2DM group (16.35% versus 7.14%, p = 0.025). Control subjects with haplotype combination 112/121 had higher serum cholesterol level than others without haplotype combination 112/121 (5.7 +/- 1.4 versus 5.2 +/- 0.7, p = 0.011). Our results suggest that haplotype combination 112/221 associated with reduced risk for T2DM and haplotype combination 112/121 might be a risk factor for increased serum cholesterol in Chinese population.

A new organotypic culture of thyroid tissue maintains three-dimensional follicles with C cells for a long term.

Thyroid follicles embedded in extracellular matrix (ECM) seem to be supplied enough oxygen by a dense network of capillaries in vivo. Air exposure (AE) causes cells to increase oxygen availability in vitro. We speculated that three-dimensional (3D) environment of ECM together with AE may be applied to a thyroid tissue-organotypic culture, simply simulating such a microenvironment of follicles. To address the issue, we performed 3D collagen gel culture of minced thyroid tissues with or without AE. Most follicles in the tissues without AE died within 7 days. In culture with AE, most of the follicles with calcitonin-positive C cells were kept for over one month. Immunohistochemistry showed that thyrocytes displayed thyroglobulin, thyrotropin receptor, thyroid transcription factor-1 (TTF-1), and pendrin, which are all crucial for thyroid function. C cells expressed calcitonin gene-related peptide and TTF-1. Our study is the first demonstration that 3D collagen gel culture with AE retains 3D thyroid follicles with C cells for a long term. This suggests that ECM and oxygen supply together may be crucial for maintenance of 3D follicle structure and function. Our method will possibly open a new path to the study of thyrocyte-C cell interaction and thyroid biology.