Effect of polymer brush architecture on antibiofouling properties

Polymer brushes show great promise in next-generation antibiofouling surfaces. Here, we have studied the influence of polymer brush architecture on protein resistance. By carefully optimizing reaction conditions, we were able to polymerize oligoglycerol-based brushes with sterically demanding linear or dendronized side chains on gold surfaces. Protein adsorption from serum and plasma was analyzed by surface plasmon resonance. Our findings reveal a pronounced dependence of biofouling on brush architecture. Bulky yet flexible side chains as in dendronized brushes provide an ideal environment to repel protein-possibly through formation of a hydration layer, which can be further enhanced by presenting free hydroxyl groups on the polymer brushes. A deeper understanding of how brush architecture influences protein resistance will ultimately enable fabrication of surface coatings tailored to specific requirements in biomedical applications.     

Subunit composition of α5-containing nicotinic receptors in the rodent habenula

Gene association studies in humans have linked the α5 subunit gene CHRNA5 to an increased risk for nicotine dependence. In the CNS, nicotinic acetylcholine receptors (nAChRs) that contain the α5 subunit are expressed at relatively high levels in the habenulo-interpeduncular system. Recent experimental evidence furthermore suggests that α5-containing receptors in the habenula play a key role in controlling the intake of nicotine in rodents. We have now analysed the subunit composition of hetero-oligomeric nAChRs in the habenula of postnatal day 18 (P18) C57Bl/6J control mice and of mice with deletions of the α5, the β2, or the β4 subunit genes. Receptors consisting of α3β4* clearly outnumbered α4β2*-containing receptors not only in P18 but also in adult mice. We found low levels of α5-containing receptors in both mice (6%) and rats (2.5% of overall nAChRs). Observations in β2 and β4 null mice indicate that although α5 requires the presence of the β4 subunit for assembling (but not of β2), α5 in wild-type mice assembles into receptors that also contain the subunits α3, β2, and β4.     

cagA gene variants in Malaysian Helicobacter pylori strains isolated from patients of different ethnic groups

Helicobacter pylori infection of a distinct subtype of cagA may lead to different pathological manifestation. The aim of this study is to determine the presence of cagA gene and its variants in H. pylori infection among different ethnic groups and its effect on gastroduodenal diseases. Overall detection of cagA among the 205 clinical isolates of H. pylori was 94%. Variations in size of the 3' region of cagA gene were examined among 192 Malaysian H. pylori cagA-positive strains. Results showed that three cagA variants differing in fragment length of PCR products were detected and designated as type A (621-651bp), type B (732-735bp) and type C (525 bp). Although there was no association between any of the cagA subtypes with peptic ulcer disease (p>0.05), an association between cagA subtypes with a specific ethnic group was observed. Specific-cagA subtype A strains were predominantly isolated from Chinese compared to Malays and Indians (p<0.0005), and cagA subtype B strains were predominantly isolated from Malays and Indians compared to Chinese (p<0.05). The cagA type A strains of H. pylori is commonly found in the Chinese patients who have a higher risk of peptic ulcer disease, thus indicating that it could be used as an important clinical biomarker for a more severe infection.     

The identification and optimization of a N-hydroxy urea series of flap endonuclease 1 inhibitors

Flap endonuclease-1 (FEN1) is a key enzyme involved in base excision repair (BER), a primary pathway utilized by mammalian cells to repair DNA damage. Sensitization to DNA damaging agents is a potential method for the improvement of the therapeutic window of traditional chemotherapeutics. In this paper, we describe the identification and SAR of a series of low nanomolar FEN1 inhibitors. Over 1000-fold specificity was achieved against a related endonuclease, xeroderma pigmentosum G (XPG). Two compounds from this series significantly potentiate the action of methyl methanesulfonate (MMS) and temozolamide in a bladder cancer cell line (T24). To our knowledge, these are the most potent endonuclease inhibitors reported to date.     

Poly(glycidyl methacrylate/divinylbenzene)-IDA-FeIII in phosphoproteomics

The study of protein phosphorylation has grown exponentially in recent years, as it became evident that important cellular functions are regulated by phosphorylation and dephosphorylation of proteins on serine, threonine and tyrosine residues. The use of immobilized metal affinity chromatography (IMAC) to enrich phosphopeptides from peptide mixtures has been shown to be useful especially prior to mass spectrometric analysis. For the selective enrichment applying solid-phase extraction (SPE) of phosphorylated peptides, we introduce poly(glycidyl methacrylate/divinylbenzene) (GMD) derivatized with imino-diacetic acid (IDA) and bound Fe(III) as a material. GMD is rapidly synthesized and the resulting free epoxy groups enable an easy access to further derivatization with, e.g., IDA. Electron microscopy showed that the synthesized GMD-IDA-Fe(III) for SPE has irregular agglomerates of spherical particles. Inductively coupled plasma (ICP) analysis resulted in a metal capacity of Fe(III) being 25.4 micromol/mL. To enable on-line preconcentration and desalting in one single step, GMD-IDA-Fe(III) and Silica C18 were united in one cartridge. Methyl esterification (ME) of free carboxyl groups was carried out to prevent binding of nonphosphorylated peptides to the IMAC function. The recovery for a standard phosphopeptide using this SPE method was determined to be 92%. The suitability of the established system for the selective enrichment and analysis of model proteins phosphorylated at different amino acid residues was evaluated stepwise. After successful enrichment of beta-casein deriving phosphopeptides, the established system was extended to the analysis of in vitro phosphorylated proteins, e.g. deriving from glutathione-S-transferase tagged extracellular signal regulated kinase 2 (GST-ERK2).     

Plasma membrane H+-ATPase is involved in auxin-mediated cell elongation during wheat embryo development

Previous investigations suggested that specific auxin spatial distribution due to auxin movements to particular embryonic regions was important for normal embryonic pattern formation. To gain information on the molecular mechanism(s) by which auxin acts to direct pattern formation in specific embryonic regions, the role of a plasma membrane (PM) ATPase was evaluated as downstream target of auxin in the present study. Western-blot analysis revealed that the PM H(+)-ATPase expression level was significantly increased by auxin in wheat (Triticum aestivum) embryos (two-three times increase). In bilaterally symmetrical embryos, the spatial expression pattern of the PM H(+)-ATPase correlates with the distribution pattern of the auxin analog, tritiated 5-azidoindole-3-acetic acid. A strong immunosignal was observed in the abaxial epidermis of the scutellum and in the epidermal cells at the distal tip of this organ. Pseudoratiometric analysis using a fluorescent pH indicator showed that the pH in the apoplast of the cells expressing the PM H(+)-ATPase was in average more acidic than the apoplastic pH of nonexpressing cells. Cellulose staining of living embryos revealed that cells of the scutellum abaxial epidermis expressing the ATPase were longer than the scutellum adaxial epidermal cells, where the protein was not expressed. Our data indicate that auxin activates the proton pump resulting in apoplastic acidification, a process contributing to cell wall loosening and elongation of the scutellum. Therefore, we suggest that the PM H(+)-ATPase is a component of the auxin-signaling cascade that may direct pattern formation in embryos.     

Food restricting young hamsters (Mesocricetus auratus) affects sex ratio and growth of subsequent offspring

Trivers and Willard (1973) predicted that stressed adult female mammals may enhance their fitness by skewing offspring sex ratios and maternal investment to favor daughters. The present study investigated whether stressing young hamsters might also influence sex ratio and growth of subsequent offspring. Control females received food ad libitum (A) on Days 1-50 postpartum (AA). Experimental females were food-restricted (R) either on Days 1-25 (RA), Days 26-50 (AR), or Days 1-50 (RR) postpartum. Subjects were mated when 91-95 days old. Litter sizes and survivorship (= % litters within a treatment that contained at least one pup), sex ratio (= % males), and pup weights in the next generation were recorded every fifth day from parturition until Day 25 postpartum. Control litters contained significantly more offspring at birth than did RR litters. Sex ratio was significantly higher at birth for AA litters than for the other treatments. Postpartum sex ratio within each group remained similar to that recorded at birth. RR litters contained significantly fewer pups compared to the other three treatments from Days 5-25. RR female pups weighed significantly more at birth than their counterparts in the other treatments. Weights of males at birth were similar in all treatments. By Day 25, both male and female RR pups weighed significantly less than control, AR, and RA pups. Food restriction early in life may have long-term consequences on sex ratio and pup growth in golden hamsters.     

Deletion,insertion, and restriction site polymorphism of the T-cell receptor gamma variable locus in French,Lebanese, Tunisian,and Black African populations

The human T-cell receptor gamma region spans 160 kb of genomic DNA and is densely populated by coding sequences. Restriction fragment length polymorphisms have been previously documented for the constant region genes, the joining segments, and the variable genes belonging to subgroups I and IV. Here were further define the polymorphism of theV gamma I subgroup genes, based on complete mapping of theEco RI andTaq I allelic restriction fragments. We describe seven haplotypes; five result from polymorphic restriction sites, the sixth corresponds to a deletion of about 10 kb encompassingV4 andV5, and the seventh results from an insertion of an additional gene,V3P, betweenV3 andV4. As a consequence of the deletion or insertion polymorphism, the number ofV gamma I subgroup genes vary from seven in haplotypeTRGVI ^*3 to ten in haplotypeTRGVI ^*4, whereas the most common haplotype,TRGVI ^*1, has nineV genes, five of them being functional. Frequencies of the differentTRGVI haplotypes in French, Lebanese, Tunisian, and Black African populations are given.