The conformation of linear gramicidin is sequence dependent

A comparative monolayer and infrared study of analogues of gramicidin A containing either tyrosines or naphthylalanines instead of tryptophans indicates that the nature of the aromatic residues influences the favoured conformation of the peptides. Polar residues favour the single stranded _DL helix while non polar residues favour the double stranded helix. For partly tryptophan to naphthylalanine substituted analogues the positions of the substitutions orientate the favored conformation. The nature of these substitutions may also modify the peptide-lipid interactions. Correspondence to: F. Heitz Chemical structures of the gramicidin A analogues mentioned in this paper. The differences from gramicidin A are underlined. GM^–: GT:     

The effect of isolated components of Prunus avium L. styles on in vitro growth of pollen tubes

A number of components isolated from styles of P. avium cv. Napoleon (S ₃ S ₄) have been tested for their capacity to influence in vitro growth of pollen tubes from fresh and stored pollen (cv. Napoleon (S ₃ S ₄)). An antigenic glycoprotein (Antigen S) is a potent inhibitor of in-vitro pollen tube growth, causing a 65% reduction in tube length at a concentration of 20 g/ml. None of the other style components were effective inhibitors of pollen tube growth; neither were proteins of animal origin such as histone, serum albumin, cytochrome C, and the glycoproteins ovalbumin and thyroglobulin, effective inhibitors.     

Up-regulation of vascular endothelial growth factor (VEGF) in small-for-size liver grafts enhances macrophage activities through VEGF receptor 2-dependent pathway

This study aims to investigate the potential role of vascular endothelial growth factor (VEGF) and VEGF-R2 (fetal liver kinase (Flk)-1) in mediating macrophage activities in small-for-size liver transplantation. A rat orthotopic liver transplantation model was performed using either whole, 50, or 30% liver grafts (both 50 and 30% were regarded as small-for-size) in syngeneic or allogeneic combinations, respectively. Firstly, the mRNA and protein levels of VEGF and Flk-1 in liver grafts were detected by RT-PCR and Western blot, and the number of Flk-1(+) macrophages (labeled by ED1) was determined by flow cytometry. It was found that the small-for-size isografts and allografts presented higher levels of VEGF and Flk-1 expression than the whole isograft and allograft. In addition, a higher number of Flk-1(+)ED1(+) cells were detected in the small-for-size isografts and allografts than the whole isograft and allograft. Secondly, our study revealed that macrophage cell lines did not initially express detectable Flk-1, but could be induced by VEGF, and the inducible expression of Flk-1 in macrophages was related to their migration and proliferation activities. Finally, our study demonstrated that the induction of Flk-1 expression on macrophages by VEGF was associated with the expression of NF-kappaB and heat shock protein 90. In conclusion, the present study showed that the up-regulated expression of VEGF and its interaction with Flk-1 in small-for-size liver grafts might facilitate the activities of macrophages.     

Evaluation of N-acetylchitooligosaccharides as the main carbon sources for the growth of intestinal bacteria

N-Acetylchitooligosaccharides ((GlcNAc)(n)) with different degrees of polymerization (n=1-6) were prepared as the main carbon sources in media for evaluating the growth of nine intestinal bacteria. A chitohydrolysate was prepared by hydrolyzing shrimp-shell chitin using HCl. After purification, the purity of each (GlcNAc)(1-6) was >86%. The growth of intestinal bacteria was carried out in a basal medium (BM) containing 0.2% (w/v) of each sugar or glucose as the main carbon source and was evaluated using maximum cell densities and specific growth rates. Bacteroides fragilis and Clostridium perfringens could respectively utilize GlcNAc and (GlcNAc)(2) more efficiently for growth than glucose. Bifidobacterium adolescentis and Eubacterium limosum could use (GlcNAc)(1-6) slightly as their main carbon source. Escherichia coli, Lactococcus lactis and Proteus vulgaris could utilize glucose more efficiently than (GlcNac)(1-6). GlcNAc was used more readily than (GlcNAc)(2-6) by Staphylococcus aureus, exhibiting almost the same specific growth rates. In BM, Streptococcus faecalis grew well even without adding each of the sugars tested.     

Molecular analysis of expansion,differentiation, and growth factor treatment of human chondrocytes identifies differentiation markers and growth-related genes

This study is intended to optimise expansion and differentiation of cultured human chondrocytes by growth factor application and to identify molecular markers to monitor their differentiation state. We dissected the molecular consequences of matrix release, monolayer, and 3D-alginate culture, growth factor optimised expansion, and re-differentiation protocols by gene expression analysis. Among 19 common cartilage molecules assessed by cDNA array, six proved best to monitor differentiation. Instant down-regulation at release of cells from the matrix was strongest for COL 2A1, fibromodulin, and PRELP while LUM, CHI3L1, and CHI3L2 were expansion-related. Both gene sets reflected the physiologic effects of the most potent growth-inducing (PDGF-BB) and proteoglycan-inducing (BMP-4) factors. Only CRTAC1 expression correlated with 2D/3D switches while the molecular phenotype of native chondrocytes was not restored. The markers and optimised protocols we suggest can help to improve cell therapy of cartilage defects and chondrocyte differentiation from stem cell sources.     

Morphological, cytochemical autoradiographic and quantitative studies of the cells in lymphocyte cultures with added tuberculin]

Lymphocyte culture experiments with purified tuberculin showed a transformation of small lymphocytes into medium sized, large and very large basophilic cells. During cell growth RNA synthesis and acid phosphatase activity increased. Some of the very large basophilic cells synthesized DNA. During the first and second day of culture experiment also medium sized and large weakly basophilic cells increased, which have a pale plasma and azurophilic granules. These cells did not synthesize DNA and showed only a low incorporation of 3H-uridine. The results of our experiments indicate a transformation of medium sized and large basophilic cells not synthesizing DNA into weakly basophilic (pale) cells showing azurophilic granules. In contrast to the lymphocyte culture experiments with tuberculin lymphocyte cultures without tuberculin showed no significant increase of medium sized, large and very large basophilic cells and of weakly basophilic cells.     

Regioselective acylation of several polyhydroxylated natural compounds by Candida antarctica lipase B

Regioselective acylation of four polyhydroxylated natural compounds, deacetyl asperulosidic acid (1), asperulosidic acid (2), puerarin (3) and resveratrol (4) by Candida antarctica Lipase B in the presence of various acyl donors (vinyl acetate, vinyl decanoate or vinyl cinnamoate) was studied. Compounds 1, 2 and 4 were regioselectively acetylated with vinyl acetate to afford products, 3′-O-acetyl-10-O-deacetylasperulosidic acid (1a), 3′,6′-O-diacetyl-10-O-deacetylasperulosidic acid (1b), 3′-O-acetylasperulosidic acid (2a), 3′,6′-O-diacetylasperulosidic acid (2b), 4′-O-acetylresveratrol (4a), respectively, with yields of 22 to 50%, while reactions with vinyl decanoate and vinyl cinnamoate were slow with lower yields. Compound 3 was readily acylated with all three acyl donors and quantitatively converted to products 6″-O-acetylpuerarin (3a), 6″-O-decanoylpuerarin (3b), 6″-O-cinnamoylpuerarin (3c), respectively. The structures of these acylated products were determined by spectroscopic methods (MS and NMR).     

The role of proline rich tyrosine kinase 2 (Pyk2) on cisplatin resistance in hepatocellular carcinoma

Aims

We previously demonstrated Proline rich tyrosine kinase 2 (Pyk2) plays important roles in regulating tumor progression, migration and invasion in hepatocellular carcinoma (HCC). In this study, we aimed to examine the role of proline rich tyrosine kinase 2 (Pyk2) on cisplatin resistance in HCC and to explore its underlying molecular mechanism.

Methodology/Principal Findings

Stable transfectants either overexpressing or suppressing Pyk2 were established in different HCC cell lines. MTT, colony formation and Annexin-V assays were employed to examine their in vitro responses to cisplatin. Xenograft ectopic and orthotopic nude mice models were generated to investigate the in vivo responses of them to cisplatin treatment. cDNA microarray was performed to identify Pyk2-induced genes which were further validated by quantitative real-time RT-PCR using clinical HCC samples. In vitro functional study demonstrated that Pyk2-overexpressing HCC transfectants exhibited relatively lower cytotoxicity, higher colony-forming ability and lower apoptosis to cisplatin compared with the control transfectants. Moreover, Pyk2 overexpressing HCC transfectants had a higher survival rate under cisplatin treatment by up-regulation of AKT phosphorylation. In vivo xenograft nude mice model demonstrated that Pyk2-overexpressing transfectants developed higher tolerance to cisplatin treatment together with less tumor necrosis and apoptosis. cDNA microarray analysis revealed that there were more than 4,000 genes differentially expressed upon overexpression of Pyk2. Several upregulated genes were found to be involved in drug resistance and invasion in cancers. Among them, the expression profiles of MDR1, GAGE1, STAT1 and MAP7 were significantly associated with the expression of Pyk2 in clinical HCC samples.

Conclusions

Our results may suggest a new evidence of Pyk2 on promoting cisplatin resistance of HCC cells through preventing cell apoptosis, activation of AKT pathway and upregulation of drug resistant genes.     

Sociodemographic,behavioral, and biological variables related to weight loss in native hawaiians and other pacific islanders

Objective:

Native Hawaiians and other Pacific Islanders (NHs/PIs) have a high obesity prevalence compared to other ethnic groups. We examined socio‐demographic, behavioral, and biological factors related to ≥3% weight loss in 100 overweight/obese NHs/PIs who completed a lifestyle intervention.

Design and Methods:

Data were from 56 Native Hawaiians, 22 Chuukese, and 22 Other Pacific Islanders who participated in a randomized controlled trial of the Partnership for Improving Lifestyle Intervention (PILI) 'Ohana Project. All completed a 3‐month weight loss program (WLP) to initiate weight loss and were then randomized into either a 6‐month family/community focused WLP called the PILI Lifestyle Program (PLP; n = 49) or a standard behavior WLP (SBP; n = 51). We collected baseline, 3‐ and 9‐month follow‐up data on socio‐demographics, weight (kg), a 6‐min. walk test, dietary fat, exercise frequency, and blood pressure.

Results and Conclusion:

Based on ANCOVA or logistic fit, ethnicity, sex, initial weight loss, fat in diet at baseline, change in systolic blood pressure, and intervention type were significantly associated (P ≤ .05) with ≥3% weight loss at 9‐month follow‐up. A logistic regression model indicated that Chuukese (OR = 6.04; CI = 1.14–32.17) and participants who had more weight loss in the first 3‐months (OR = 1.47; CI = 1.22–1.86) and who were in the PLP (OR = 4.50; CI = 1.50–15.14) were more likely to achieve ≥3% weight loss [model; χ² (7, N = 100) = 45.50, P < .0001]. The same lifestyle intervention does not benefit all NHs/PIs equally, possibly due to differences in acculturation status and social support. The findings also point to the importance of initial weight loss to sustain motivation toward long‐term weight loss maintenance.     

Structural Insights into the Dual Strategy of Recognition by Peptidoglycan Recognition Protein,PGRP-S: Structure of the Ternary Complex of PGRP-S with Lipopolysaccharide and Stearic Acid

Peptidoglycan recognition proteins (PGRPs) are part of the innate immune system. The 19 kDa Short PGRP (PGRP-S) is one of the four mammalian PGRPs. The concentration of PGRP-S in camel (CPGRP-S) has been shown to increase considerably during mastitis. The structure of CPGRP-S consists of four protein molecules designated as A, B, C and D forming stable intermolecular contacts, A–B and C–D. The A–B and C–D interfaces are located on the opposite sides of the same monomer leading to the the formation of a linear chain with alternating A–B and C–D contacts. Two ligand binding sites, one at C–D contact and another at A–B contact have been observed. CPGRP-S binds to the components of bacterial cell wall molecules such as lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PGN) from both Gram-positive and Gram-negative bacteria. It also binds to fatty acids including mycolic acid of the Mycobacterium tuberculosis (Mtb). Previous structural studies of binary complexes of CPGRP-S with LPS and stearic acid (SA) have shown that LPS binds to CPGRP-S at C–D contact (Site-1) while SA binds to it at the A–B contact (Site-2). The binding studies using surface plasmon resonance showed that LPS and SA bound to CPGRP-S in the presence of each other. The structure determination of the ternary complex showed that LPS and SA bound to CPGRP-S at Site-1 and Site-2 respectively. LPS formed 13 hydrogen bonds and 159 van der Waals contacts (distances ≤4.2 Å) while SA formed 56 van der Waals contacts. The ELISA test showed that increased levels of productions of pro-inflammatory cytokines TNF-α and IFN-γ due to LPS and SA decreased considerably upon the addition of CPGRP-S.