Novel Alligator Cathelicidin As-CATH8 Demonstrates Anti-Infective Activity against Clinically Relevant and Crocodylian Bacterial Pathogens.

Host defense peptides (HDPs) represent an alternative way to address the emergence of antibiotic resistance. Crocodylians are interesting species for the study of these molecules because of their potent immune system, which confers high resistance to infection. Profile hidden Markov models were used to screen the genomes of four crocodylian species for encoded cathelicidins and eighteen novel sequences were identified. Synthetic cathelicidins showed broad spectrum antimicrobial and antibiofilm activity against several clinically important antibiotic-resistant bacteria. In particular, the As-CATH8 cathelicidin showed potent in vitro activity profiles similar to the last-resort antibiotics vancomycin and polymyxin B. In addition, As-CATH8 demonstrated rapid killing of planktonic and biofilm cells, which correlated with its ability to cause cytoplasmic membrane depolarization and permeabilization as well as binding to DNA. As-CATH8 displayed greater antibiofilm activity than the human cathelicidin LL-37 against methicillin-resistant Staphylococcus aureus in a human organoid model of biofilm skin infection. Furthermore, As-CATH8 demonstrated strong antibacterial effects in a murine abscess model of high-density bacterial infections against clinical isolates of S. aureus and Acinetobacter baumannii, two of the most common bacterial species causing skin infections globally. Overall, this work expands the repertoire of cathelicidin peptides known in crocodylians, including one with considerable therapeutic promise for treating common skin infections.

Peptide 1018 inhibits swarming and influences Anr-regulated gene expression downstream of the stringent stress response in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen that causes considerable human morbidity and mortality, particularly in nosocomial infections and individuals with cystic fibrosis. P. aeruginosa can adapt to surface growth by undergoing swarming motility, a rapid multicellular movement that occurs on viscous soft surfaces with amino acids as a nitrogen source. Here we tested the small synthetic host defense peptide, innate defense regulator 1018, and found that it inhibited swarming motility at concentrations as low as 0.75 µg/ml, well below the MIC for strain PA14 planktonic cells (64 µg/ml). A screen of the PA14 transposon insertion mutant library revealed 29 mutants that were more tolerant to peptide 1018 during swarming, five of which demonstrated significantly greater swarming than the WT in the presence of peptide. Transcriptional analysis (RNA-Seq) of cells that were inoculated on swarming plates containing 1.0 µg/ml peptide revealed differential expression of 1,190 genes compared to cells swarming on plates without peptide. Furthermore, 1018 treatment distinctly altered the gene expression profile of cells when compared to that untreated cells in the centre of the swarm colonies. Peptide-treated cells exhibited changes in the expression of genes implicated in the stringent stress response including those regulated by anr, which is involved in anaerobic adaptation, indicative of a mechanism by which 1018 might inhibit swarming motility. Overall, this study illustrates potential mechanisms by which peptide 1018 inhibits swarming surface motility, an important bacterial adaptation associated with antibiotic resistance, virulence, and dissemination of P. aeruginosa.

In vivo Anti-inflammatory Activity of Lipidated Peptidomimetics Pam-(Lys-ßNspe)6-NH2 and Lau-(Lys-ßNspe)6-NH2 Against PMA-Induced Acute Inflammation.

Host Defense Peptides (HDPs) are key components of innate immunity that exert antimicrobial, antibiofilm, and immunomodulatory activities in all higher organisms. Synthetic peptidomimetic analogs were designed to retain the desirable pharmacological properties of HDPs while having improved stability toward enzymatic degradation, providing enhanced potential for therapeutic applications. Lipidated peptide/ß-peptoid hybrids [e.g., Pam-(Lys-ßNspe)6-NH2 (PM1) and Lau-(Lys-ßNspe)6-NH2 (PM2)] are proteolytically stable HDP mimetics displaying anti-inflammatory activity and formyl peptide receptor 2 antagonism in human and mouse immune cells in vitro. Here PM1 and PM2 were investigated for their in vivo anti-inflammatory activity in a phorbol 12-myristate 13-acetate (PMA)-induced acute mouse ear inflammation model. Topical administration of PM1 or PM2 led to attenuated PMA-induced ear edema, reduced local production of the pro-inflammatory chemokines MCP-1 and CXCL-1 as well as the cytokine IL-6. In addition, diminished neutrophil infiltration into PMA-inflamed ear tissue and suppressed local release of reactive oxygen and nitrogen species were observed upon treatment. The obtained results show that these two peptidomimetics exhibit anti-inflammatory effects comparable to that of the non-steroidal anti-inflammatory drug indomethacin, and hence possess a potential for treatment of inflammatory skin conditions.

Clinical and biochemical features guiding the diagnostics in neurometabolic cutis laxa.

Patients with cutis laxa (CL) have wrinkled, sagging skin with decreased elasticity. Skin symptoms are associated with variable systemic involvement. The most common, genetically highly heterogeneous form of autosomal recessive CL, ARCL2, is frequently associated with variable metabolic and neurological symptoms. Progeroid symptoms, dysmorphic features, hypotonia and psychomotor retardation are highly overlapping in the early phase of these disorders. This makes the genetic diagnosis often challenging. In search for discriminatory symptoms, we prospectively evaluated clinical, neurologic, metabolic and genetic features in our patient cohort referred for suspected ARCL. From a cohort of 26 children, we confirmed mutations in genes associated with ARCL in 16 children (14 probands), including 12 novel mutations. Abnormal glycosylation and gyration abnormalities were mostly, but not always associated with ATP6V0A2 mutations. Epilepsy was most common in ATP6V0A2 defects. Corpus callosum dysgenesis was associated with PYCR1 and ALDH18A1 mutations. Dystonic posturing was discriminatory for PYCR1 and ALDH18A1 defects. Metabolic markers of mitochondrial dysfunction were found in one patient with PYCR1 mutations. So far unreported white matter abnormalities were found associated with GORAB and RIN2 mutations. We describe a large cohort of CL patients with neurologic involvement. Migration defects and corpus callosum hypoplasia were not always diagnostic for a specific genetic defect in CL. All patients with ATP6V0A2 defects had abnormal glycosylation. To conclude, central nervous system and metabolic abnormalities were discriminatory in this genetically heterogeneous group, although not always diagnostic for a certain genetic defect in CL.

Cytotoxicity of quantum dots used for in vitro cellular labeling: role of QD surface ligand, delivery modality, cell type, and direct comparison to organic fluorophores.

Interest in taking advantage of the unique spectral properties of semiconductor quantum dots (QDs) has driven their widespread use in biological applications such as in vitro cellular labeling/imaging and sensing. Despite their demonstrated utility, concerns over the potential toxic effects of QD core materials on cellular proliferation and homeostasis have persisted, leaving in question the suitability of QDs as alternatives for more traditional fluorescent materials (e.g., organic dyes, fluorescent proteins) for in vitro cellular applications. Surprisingly, direct comparative studies examining the cytotoxic potential of QDs versus these more traditional cellular labeling fluorophores remain limited. Here, using CdSe/ZnS (core/shell) QDs as a prototypical assay material, we present a comprehensive study in which we characterize the influence of QD dose (concentration and incubation time), QD surface capping ligand, and delivery modality (peptide or cationic amphiphile transfection reagent) on cellular viability in three human cell lines representing various morphological lineages (epithelial, endothelial, monocytic). We further compare the effects of QD cellular labeling on cellular proliferation relative to those associated with a panel of traditionally employed organic cell labeling fluorophores that span a broad spectral range. Our results demonstrate the important role played by QD dose, capping ligand structure, and delivery agent in modulating cellular toxicity. Further, the results show that at the concentrations and time regimes required for robust QD-based cellular labeling, the impact of our in-house synthesized QD materials on cellular proliferation is comparable to that of six commercial cell labeling fluorophores. Cumulatively, our results demonstrate that the proper tuning of QD dose, surface ligand, and delivery modality can provide robust in vitro cell labeling reagents that exhibit minimal impact on cellular viability.

1,25-Dihydroxyvitamin D3 inhibits the cytokine-induced secretion of MCP-1 and reduces monocyte recruitment by human preadipocytes.

BACKGROUND: Adipose tissue expansion during obesity is associated with a state of low-grade inflammation and an increase in macrophage infiltration, which predisposes to insulin resistance and vascular malfunction. Growing evidence suggests that vitamin D3 has immunoregulatory effects and adipose tissue could be a target for vitamin D3 action. Preadipocytes, one of the major cell types in adipose tissue, are actively involved in inflammatory processes. OBJECTIVES: This study investigated whether the active form of vitamin D3 (1,25(OH)2D3) affects the production of proinflammatory chemokines/cytokines and the monocyte recruitment by human preadipocytes. METHODS/RESULTS: The secretion levels of monocyte chemoattractant proteint-1 (MCP-1), IL-8 and IL-6 were significantly higher in preadipocytes than in differentiated adipocytes, suggesting that preadipocytes could be a major source of proinflammatory mediators. Cytokine profile analysis revealed that 1,25(OH)2D3 (10 nM) markedly reduced the release of MCP-1, IL-6 and IL-8 by preadipocytes. The involvement of NFκB signalling was shown by the upregulation of IκBα protein abundance by 1,25(OH)2D3 in preadipocytes. In addition, 1,25(OH)2D3 was able to decrease the migration of THP-1 monocytes. Treatment with proinflammatory stimuli, including macrophage-conditioned (MC) medium, TNFα and IL-1ß, led to a marked increase in protein release of MCP-1 and IL-6 by preadipocytes. Pretreatment with 1,25(OH)2D3 (10 nM and 100 nM) significantly decreased the stimulatory effects of MC medium, TNFα and IL-1ß on MCP-1 expression and protein release, although the effect on stimulated release of IL-6 was less potent. CONCLUSIONS: These results demonstrate that 1,25(OH)2D3 decreases the production of MCP-1 and other proinflammatory mediators by preadipocytes and reduces monocyte migration. Thus, vitamin D3 may protect against adipose tissue inflammation by disrupting the deleterious cycle of macrophage recruitment.

Spatiotemporal multicolor labeling of individual cells using peptide-functionalized quantum dots and mixed delivery techniques.

Multicolor fluorescent labeling of both intra- and extracellular structures is a powerful technique for simultaneous monitoring of multiple complex biochemical processes. This approach remains extremely challenging, however, as it often necessitates the combinatorial use of numerous targeting probes (e.g., antibodies), multistep bioconjugation chemistries, different delivery strategies (e.g., electroporation or transfection reagents), cellular fixation coupled with membrane permeabilization, and complex spectral deconvolution. Here, we present a nanoparticle-based fluorescence labeling strategy for the multicolor labeling of distinct subcellular compartments within live cells without the need for antibody conjugation or cellular fixation/permeabilization. This multipronged approach incorporates an array of delivery strategies, which localize semiconductor quantum dots (QDs) to various subcellular structures. QD uptake is implemented in a spaciotemporal manner by staggering the delivery of QD-peptide composites and exploiting various innate (peptide-mediated endocytosis, peptide-membrane interaction, polymer-based transfection) along with physical (microinjection) cellular delivery modalities to live cells growing in culture over a 4 day period. Imaging of the different intracellular labels is simplified by the unique photophysical characteristics of the QDs in combination with Förster resonance energy transfer sensitization, which allow for multiple spectral windows to be accessed with one excitation wavelength. Using this overall approach, QDs were targeted to both early and late endosomes, the cellular cytosol, and the plasma membrane in live cells, ultimately allowing for simultaneous five-color fluorescent imaging.

Enhanced ZAG production by subcutaneous adipose tissue is linked to weight loss in gastrointestinal cancer patients.

BACKGROUND: Profound loss of adipose tissue is a hallmark of cancer cachexia. Zinc-α2-glycoprotein (ZAG), a recently identified adipokine, is suggested as a candidate in lipid catabolism. METHODS: In the first study, eight weight-stable and 17 cachectic cancer patients (weight loss 5% in previous 6 months) were recruited. Zinc-α2-glycoprotein mRNA and protein expression were assessed in subcutaneous adipose tissue (SAT), subcutaneous adipose tissue morphology was examined and serum ZAG concentrations were quantified. In the second cohort, ZAG release by SAT was determined in 18 weight-stable and 15 cachectic cancer patients. The effect of ZAG on lipolysis was evaluated in vitro. RESULTS: Subcutaneous adipose tissue remodelling in cancer cachexia was evident through shrunken adipocytes with increased fibrosis. In cachectic cancer patients, ZAG mRNA was upregulated (2.7-fold, P=0.028) while leptin mRNA decreased (2.2-fold, P=0.018); serum ZAG levels were found to be unaffected. Zinc-α2-glycoprotein mRNA correlated positively with weight loss (r=0.51, P=0.01) and serum glycerol levels (r=0.57, P=0.003). Zinc-α2-glycoprotein release by SAT was also elevated in cachectic patients (1.5-fold, P=0.024) and correlated with weight loss (r=0.50, P=0.003). Recombinant ZAG stimulated lipolysis in human adipocytes. CONCLUSIONS: Zinc-α2-glycoprotein expression and secretion by adipose tissue is enhanced in cachectic cancer patients. Given its lipid-mobilising effect, ZAG may contribute to adipose atrophy associated with cancer cachexia in human beings.

Quantum dot peptide biosensors for monitoring caspase 3 proteolysis and calcium ions.

The nanoscale size and unique optical properties of semiconductor quantum dots (QDs) have made them attractive as central photoluminescent scaffolds for a variety of biosensing platforms. In this report we functionalize QDs with dye-labeled peptides using two different linkage chemistries to yield Förster resonance energy transfer (FRET)-based sensors capable of monitoring either enzymatic activity or ionic presence. The first sensor targets the proteolytic activity of caspase 3, a key downstream effector of apoptosis. This QD conjugate utilized carbodiimide chemistry to covalently link dye-labeled peptide substrates to the terminal carboxyl groups on the QD's surface hydrophilic ligands in a quantitative manner. Caspase 3 cleaved the peptide substrate and disrupted QD donor-dye acceptor FRET providing signal transduction of enzymatic activity and allowing derivation of relevant Michaelis-Menten kinetic descriptors. The second sensor was designed to monitor Ca2+ ions that are ubiquitous in many biological processes. For this sensor, Cu+-catalyzed [3 + 2] azide-alkyne cycloaddition was exploited to attach a recently developed azide-functionalized CalciumRuby-Cl indicator dye to a cognate alkyne group present on the terminus of a modified peptide. The labeled peptide also expressed a polyhistidine sequence, which facilitated its subsequent metal-affinity coordination to the QD surface establishing the final FRET sensing construct. Adding exogenous Ca2+ to the sensor solution increased the dyes fluorescence, altering the donor-acceptor emission ratio and manifested a dissociation constant similar to that of the native dye. These results highlight the potential for combining peptides with QDs using different chemistries to create sensors for monitoring chemical compounds and biological processes.

Quantum-dot/dopamine bioconjugates function as redox coupled assemblies for in vitro and intracellular pH sensing.

The use of semiconductor quantum dots (QDs) for bioimaging and sensing has progressively matured over the past decade. QDs are highly sensitive to charge-transfer processes, which can alter their optical properties. Here, we demonstrate that QD-dopamine-peptide bioconjugates can function as charge-transfer coupled pH sensors. Dopamine is normally characterized by two intrinsic redox properties: a Nernstian dependence of formal potential on pH and oxidation of hydroquinone to quinone by O(2) at basic pH. We show that the latter quinone can function as an electron acceptor quenching QD photoluminescence in a manner that depends directly on pH. We characterize the pH-dependent QD quenching using both electrochemistry and spectroscopy. QD-dopamine conjugates were also used as pH sensors that measured changes in cytoplasmic pH as cells underwent drug-induced alkalosis. A detailed mechanism describing the QD quenching processes that is consistent with dopamine's inherent redox chemistry is presented.

Macrophage-secreted factors inhibit ZAG expression and secretion by human adipocytes.

Zinc-alpha2-glycoprotein (ZAG), a novel adipokine, is downregulated in adipose tissue in obesity, a state characterized by increased adipose tissue macrophage infiltration and chronic low-grade inflammation. This study investigated whether macrophage-secreted factors and TNF-alpha, a major product of macrophages, modulate ZAG expression and secretion by human adipocytes. ZAG was produced primarily by adipocytes, and not by preadipocytes and macrophages. Incubation of preadipocytes with macrophage-conditioned medium for up to 12 days decreased ZAG mRNA and protein release, and the expression of adipogenic markers (PPARgamma and C/EBPalpha). Adipocytes treated with macrophage-conditioned medium for 24h displayed significant reductions in ZAG mRNA and release. Chronic TNF-alpha treatment let to significant decreases in ZAG expression and secretion, but marked upregulation of pro-inflammatory cytokines and chemokines (IL-6, leptin, IL-8, MCP-1 and RANTES) in adipocytes. These findings suggest that macrophage-associated inflammation may play a significant role in the downregulation of ZAG in adipose tissue in obesity.

Upregulation of the expression of inflammatory and angiogenic markers in human adipocytes by a synthetic cannabinoid, JTE-907.

Inflammation in adipose tissue is a characteristic of obesity and the metabolic syndrome. It is suggested that the endocannabinoid system is involved in the regulation of inflammatory and angiogenic processes within the tissue. Human subcutaneous preadipocytes (Zen Bio) were used as the source of human preadipocytes or adipocytes. Gene expression was examined by RT-PCR and real-time PCR. The secretion of inflammation-related proteins was determined by an ELISA array. In experiments on adipocytes treated at day 14 post-differentiation, JTE-907, a synthetic cannabinoid, upregulated the expression of key inflammatory markers - IL-6, MCP-1 and IL-1 beta - and angiogenic factors - VEGF and ANGPTL4 - at 10 microM after 20 h of treatment, having also increased the expression of TRPV1 at 10 microM. JTE-907 showed no effect after 4 h. The ELISA array showed a 2.6-fold increase in IL-6 protein release. The effect of JTE-907 was inhibited by AM251 (CB1 antagonist), and partially by arachidonyl serotonin (TRPV1 and FAAH antagonist). The CB2 antagonist, AM630, partially upregulated the effect of JTE-907. Preadipocytes fed 14 days after 100% confluence exhibited downregulation of CB1, MCP-1, and IL-1 beta, 20 h after having been exposed to JTE-907. CB1 and TRPV1 receptors participate in the regulation of several inflammatory and angiogenic factors in human adipocytes, indicating their potential value as targets for the treatment of disorders related to obesity.

Multidentate poly(ethylene glycol) ligands provide colloidal stability to semiconductor and metallic nanocrystals in extreme conditions.

We present the design and synthesis of a new set of poly(ethylene glycol) (PEG)-based ligands appended with multidentate anchoring groups and test their ability to provide colloidal stability to semiconductor quantum dots (QDs) and gold nanoparticles (AuNPs) in extreme buffer conditions. The ligands are made of a PEG segment appended with two thioctic acid (TA) or two dihydrolipoic acid (DHLA) anchoring groups, bis(TA)-PEG-OCH(3) or bis(DHLA)-PEG-OCH(3). The synthesis utilizes Michael addition to create a branch point at the end of a PEG chain combined with carbodiimide-coupling to attach two TA groups per PEG chain. Dispersions of CdSe-ZnS core-shell QDs and AuNPs with remarkable long-term colloidal stability at pHs ranging from 1.1 to 13.9 and in the presence of 2 M NaCl have been prepared and tested using these ligands. AuNPs with strong resistance to competition from dithiothreitol (as high as 1.5 M) have also been prepared. This opens up possibilities for using them as stable probes in a variety of bio-related studies where resistance to degradation at extreme pHs, at high electrolyte concentration, and in thiol-rich environments is highly desirable. The improved colloidal stability of nanocrystals afforded by the tetradentate ligands was further demonstrated via the assembly of stable QD-nuclear localization signal peptide bioconjugates that promoted intracellular uptake.

Delivering quantum dot-peptide bioconjugates to the cellular cytosol: escaping from the endolysosomal system.

For luminescent quantum dots (QDs) to realize their full potential as intracellular labeling, imaging and sensing reagents, robust noninvasive methods for their delivery to the cellular cytosol must be developed. Our aim in this study was to explore a range of methods aimed at delivering QDs to the cytosol. We have previously shown that QDs functionalized with a polyarginine 'Tat' cell-penetrating peptide (CPP) could be specifically delivered to cells via endocytic uptake with no adverse effects on cellular proliferation. We began by assessing the long-term intracellular fate and stability of these QD-peptide conjugates. We found that the QDs remained sequestered within acidic endolysosomal vesicles for at least three days after initial uptake while the CPP appeared to remain stably associated with the QD throughout this time. We next explored techniques designed to either actively deliver QDs directly to the cytosol or to combine endocytosis with subsequent endosomal escape to the cytosol in several eukaryotic cell lines. Active delivery methods such as electroporation and nucleofection delivered only modest amounts of QDs to the cytosol as aggregates. Delivery of QDs using a variety of transfection polymers also resulted in primarily endosomal sequestration of QDs. However, in one case the commercial PULSin reagent did facilitate a modest cytosolic dispersal of QDs, but only after several days in culture and with significant polymer-induced cytotoxicity. Finally, we demonstrated that an amphiphilic peptide designed to mediate cell penetration and vesicle membrane interactions could mediate rapid QD uptake by endocytosis followed by a slower efficient endosomal release which peaked at 48 h after initial delivery. Importantly, this QD-peptide bioconjugate elicited minimal cytotoxicity in the cell lines tested.

Zinc-α2-glycoprotein: an adipokine modulator of body fat mass?

The importance of white adipose tissue in the control of energy balance is now firmly recognized. In addition to fuel storage, adipocytes secrete an array of proteins factors (adipokines), which regulate multiple physiological and metabolic processes as well as influence body fat accumulation. Zinc-α2-glycoprotein (ZAG), a lipid mobilizing factor initially characterized as a tumor product associated with cachexia, has recently been identified as a novel adipokine. Although the exact role of ZAG in adipose tissue remains to be clarified, there is evidence that ZAG expression appears to be inversely related to adiposity, being upregulated in cachexia whereas reduced in obesity. Investigations on the regulation of ZAG give insights into its potential function in adipose tissue with a link to lipid mobilization and an anti-inflammatory action. Recent work shows that ZAG stimulates adiponectin secretion by human adipocytes. Data from genetic studies suggest that ZAG may be a candidate gene for body weight regulation; this is supported by the demonstration that ZAG-knockout mice are susceptible to weight gain, whereas transgenic mice overexpressing ZAG exhibit weight loss. The present review summarizes these new perspectives of ZAG and the potential mechanisms by which it might modulate adipose tissue mass and function.

Surface ligand effects on metal-affinity coordination to quantum dots: implications for nanoprobe self-assembly.

The conjugation of biomolecules such as proteins and peptides to semiconductor quantum dots (QD) is a critical step in the development of QD-based imaging probes and nanocarriers. Such protein-QD assemblies can have a wide range of biological applications including in vitro protein assays and live-cell fluorescence imaging. One conjugation scheme that has a number of advantages is the self-assembly of biomolecules on a QD surface via polyhistidine coordination. This approach has been demonstrated using QDs that have different coating types, resulting in different interactions between the biomolecule and QD surface. Here, we report the use of a fluorescence resonance energy transfer (FRET) assay to evaluate the self-assembly of fluorescent proteins on the surface of QDs with eight distinct coatings, including several used in commercial preparations. The results of this systematic comparison can provide a basis for rational design of self-assembled biomolecule-QD complexes for biomedical applications.

Combining chemoselective ligation with polyhistidine-driven self-assembly for the modular display of biomolecules on quantum dots.

One of the principle hurdles to wider incorporation of semiconductor quantum dots (QDs) in biology is the lack of facile linkage chemistries to create different types of functional QD--bioconjugates. A two-step modular strategy for the presentation of biomolecules on CdSe/ZnS core/shell QDs is described here which utilizes a chemoselective, aniline-catalyzed hydrazone coupling chemistry to append hexahistidine sequences onto peptides and DNA. This specifically provides them the ability to ratiometrically self-assemble to hydrophilic QDs. The versatility of this labeling approach was highlighted by ligating proteolytic substrate peptides, an oligoarginine cell-penetrating peptide, or a DNA-probe to cognate hexahistidine peptidyl sequences. The modularity allowed subsequently self-assembled QD constructs to engage in different types of targeted bioassays. The self-assembly and photophysical properties of individual QD conjugates were first confirmed by gel electrophoresis and Forster resonance energy transfer analysis. QD-dye-labeled peptide conjugates were then used as biosensors to quantitatively monitor the proteolytic activity of caspase-3 or elastase enzymes from different species. These sensors allowed the determination of the corresponding kinetic parameters, including the Michaelis constant (K(M)) and the maximum proteolytic activity (V(max)). QDs decorated with cell-penetrating peptides were shown to be successfully internalized by HEK 293T/17 cells, while nanocrystals displaying peptide--DNA conjugates were utilized as fluorescent probes in hybridization microarray assays. This modular approach for displaying peptides or DNA on QDs may be extended to other more complex biomolecules such as proteins or utilized with different types of nanoparticle materials.

The adipokine zinc-alpha2-glycoprotein (ZAG) is downregulated with fat mass expansion in obesity.

INTRODUCTION: Zinc-alpha2-glycoprotein (ZAG) is a novel adipokine, which may act locally to influence adipocyte metabolism. This study assessed the effect of increased adiposity on ZAG expression in adipose tissue in human subjects. The study also examined the association between ZAG and adiponectin expression in human adipose tissue, and whether ZAG modulates adiponectin secretion by human adipocytes. METHODS: Adipose tissue (visceral and subcutaneous) was collected from human subjects with a wide range of BMIs. Human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were used for in vitro studies. ZAG mRNA levels were quantified by real-time PCR and protein by Western blotting. RESULTS: In human subjects, ZAG mRNA level was negatively correlated with BMI (r = -0.61, P < 0.001, n = 23, visceral; r = -0.6, P < 0.05, n = 14, subcutaneous) and fat mass (r = -0.62, P < 0.01, visceral; r = -0.6, P < 0.05, subcutaneous). Negative associations were also found between ZAG mRNA and insulin resistance parameters including plasma insulin (r = -0.65, P < 0.001, visceral; r = -0.55, P < 0.05, subcutaneous) and homeostasis model of insulin resistance (HOMA-IR) (r = -0.65, P < 0.001, visceral; r = -0.52, P = 0.055, subcutaneous), and C reactive protein (CRP) (r = -0.46, P < 0.05, visceral; r = -0.53, P < 0.05, subcutaneous). However, ZAG mRNA was positively correlated with adiponectin (r = 0.5, P < 0.05, visceral; r = 0.82, P < 0.001, subcutaneous) but negatively associated with leptin mRNA (r = -0.42, P < 0.05, visceral; r = -0.54, P < 0.05, subcutaneous). ZAG secretion by differentiated human adipocytes was abundant. Addition of recombinant ZAG stimulated adiponectin release from human adipocytes. CONCLUSION: ZAG gene expression in adipose tissue is downregulated with increased adiposity and circulating insulin. ZAG mRNA is positively correlated with adiponectin mRNA, and ZAG enhances adiponectin production by human adipocytes. We suggest that ZAG is linked to obesity and obesity-related insulin resistance.

Downregulation of zinc-{alpha}2-glycoprotein in adipose tissue and liver of obese ob/ob mice and by tumour necrosis factor-alpha in adipocytes.

Zinc-alpha2-glycoprotein (ZAG, also listed as AZGP1 in the MGI Database), a lipid-mobilising factor, has recently been suggested as a potential candidate in the modulation of body weight. We investigated the effect of increased adiposity on ZAG expression in adipose tissue and the liver and on plasma levels in obese (ob/ob) mice compared with lean siblings. The study also examined the effect of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNFalpha) on ZAG expression in adipocytes. Zag mRNA levels were significantly reduced in subcutaneous (fourfold) and epididymal (eightfold) fat of ob/ob mice. Consistently, ZAG protein content was decreased in both fat depots of ob/ob mice. In the liver of obese animals, steatosis was accompanied by the fall of both Zag mRNA (twofold) and ZAG protein content (2.5-fold). Plasma ZAG levels were also decreased in obese mice. In addition, Zag mRNA was reduced in epididymal (fivefold) and retroperitoneal (fivefold) adipose tissue of obese (fa/fa) Zucker rats. In contrast to Zag expression, Tnfalpha mRNA levels were elevated in adipose tissue (twofold) and the liver (2.5-fold) of ob/ob mice. Treatment with TNFalpha reduced Zag gene expression in differentiated adipocytes, and this inhibition was chronic, occurring at 24 and 48 h following TNFalpha treatment. It is concluded that ZAG synthesis in adipose tissue and the liver is downregulated, as are its circulating levels, in ob/ob mice. The reduced ZAG production may advance the susceptibility to lipid accumulation in these tissues in obesity, and this could be at least in part attributable to the inhibitory effect of TNFalpha.

Effects of ligand coordination number and surface curvature on the stability of gold nanoparticles in aqueous solutions.

The colloidal stability of gold nanoparticles (AuNPs) cap-exchanged with either monothiol- or dithiolane-terminated PEG-OCH(3) ligands was investigated. Three distinct aspects were explored: (1) effects of excess salt concentration; (2) ligation competition by dithiothreitol (DTT); and (3) resistance to sodium cyanide digestion. We found that overall ligands presenting higher coordination numbers (dithiolane) exhibit much better stability to excess added salt and against competition from DTT compared to their monodentate counterparts. Resistance to NaCN digestion indicated that there is a balance between coordination number and density of ligand packing on the NP surface. For smaller NPs, where a larger surface curvature reduces the ligand packing density, a higher coordination number is clearly beneficial. In comparison, a higher ligand density allowed by the smaller curvature for larger nanocrystals makes monothiol-PEG-capped NPs more resistant to cyanide digestion. The present study indicates that balance between the coordination number and surface packing density is crucial to enhancing the colloidal stability of AuNPs.