Spontaneous remodeling of HDL particles at acidic pH enhances their capacity to induce cholesterol efflux from human macrophage foam cells

HDL particles may enter atherosclerotic lesions having an acidic intimal fluid. Therefore, we investigated whether acidic pH would affect their structural and functional properties. For this purpose, HDL(2) and HDL(3) subfractions were incubated for various periods of time at different pH values ranging from 5.5 to 7.5, after which their protein and lipid compositions, size, structure, and cholesterol efflux capacity were analyzed. Incubation of either subfraction at acidic pH induced unfolding of apolipoproteins, which was followed by release of lipid-poor apoA-I and ensuing fusion of the HDL particles. The acidic pH-modified HDL particles exhibited an enhanced ability to promote cholesterol efflux from cholesterol-laden primary human macrophages. Importantly, treatment of the acidic pH-modified HDL with the mast cell-derived protease chymase completely depleted the newly generated lipid-poor apoA-I, and prevented the acidic pH-dependent increase in cholesterol efflux. The above-found pH-dependent structural and functional changes were stronger in HDL(3) than in HDL(2). Spontaneous acidic pH-induced remodeling of mature spherical HDL particles increases HDL-induced cholesterol efflux from macrophage foam cells, and therefore may have atheroprotective effects.     

An apoA-I mimetic peptibody generates HDL-like particles and increases alpha-1 HDL subfraction in mice

The aim of this study is to investigate the capability of an apoA-I mimetic with multiple amphipathic helices to form HDL-like particles in vitro and in vivo. To generate multivalent helices and to track the peptide mimetic, we have constructed a peptibody by fusing two tandem repeats of 4F peptide to the C terminus of a murine IgG Fc fragment. The resultant peptidbody, mFc-2X4F, dose-dependently promoted cholesterol efflux in vitro, and the efflux potency was superior to monomeric 4F peptide. Like apoA-I, mFc-2X4F stabilized ABCA1 in J774A.1 and THP1 cells. The peptibody formed larger HDL particles when incubated with cultured cells compared with those by apoA-I. Interestingly, when administered to mice, mFc-2X4F increased both pre-β and α-1 HDL subfractions. The lipid-bound mFc-2X4F was mostly in the α-1 migrating subfraction. Most importantly, mFc-2X4F and apoA-I were found to coexist in the same HDL particles formed in vivo. These data suggest that the apoA-I mimetic peptibody is capable of mimicking apoA-I to generate HDL particles. The peptibody and apoA-I may work cooperatively to generate larger HDL particles in vivo, either at the cholesterol efflux stage and/or via fusion of HDL particles that were generated by the peptibody and apoA-I individually.     

Dimebon attenuates methamphetamine, but not MPTP, striatal dopamine depletion

Dimebon is an anti-histamine with central nervous system activity. In this report the effects of dimebon as a neuroprotectant in animal models of Parkinson's disease were tested as assessed in methamphetamine- and MPTP-induced striatal dopaminergic toxicity. Dimebon (1mg/kg) administered at 30 min prior to methamphetamine (40mg/kg) significantly reduced the amount of striatal dopamine depletion in mice, without altering the initial methamphetamine-induced increase in body temperature. In contrast, dimebon at either 1 or 25mg/kg administered at 30 min prior to MPTP (35 mg/kg) was unable to prevent MPTP-induced striatal dopamine loss as determined at 7 days post-methamphetamine/MPTP. These data suggest that dimebon may be exerting a neurotoxin specific neuroprotective effect upon the striatal dopaminergic system and may serve as an important tool for discriminating the mechanistic basis of these two dopaminergic neurotoxins.     

Kinin-mediated inflammation in neurodegenerative disorders

The mediatory role of kinins in both acute and chronic inflammation within nervous tissues has been widely described. Bradykinin, the major representative of these bioactive peptides, is one of a few mediators of inflammation that directly stimulates afferent nerves due to the broad expression of specific kinin receptors in cell types in these tissues. Moreover, kinins may be delivered to a site of injury not only after their production at the endothelium surface but also following their local production through the enzymatic degradation of kininogens at the surface of nerve cells. A strong correlation between inflammatory processes and neurodegeneration has been established. The activation of nerve cells, particularly microglia, in response to injury, trauma or infection initiates a number of reactions in the neuronal neighborhood that can lead to cell death after the prolonged action of inflammatory substances. In recent years, there has been a growing interest in the effects of kinins on neuronal destruction. In these studies, the overexpression of proteins involved in kinin generation or of kinin receptors has been observed in several neurologic disorders including neurodegenerative diseases such Alzheimer's disease and multiple sclerosis as well as disorders associated with a deficiency in cell communication such as epilepsy. This review is focused on recent findings that provide reliable evidence of the mediatory role of kinins in the inflammatory responses associated with different neurological disorders. A deeper understanding of the role of kinins in neurodegenerative diseases is likely to promote the future development of new therapeutic strategies for the control of these disorders. An example of this could be the prospective use of kinin receptor antagonists.     

Differential leaf expansion can enable hydraulic acclimation to sun and shade

Although leaf size is one of the most responsive plant traits to environmental change, the functional benefits of large versus small leaves remain unclear. We hypothesized that modification of leaf size within species resulting from differences in irradiance can allow leaves to acclimate to different photosynthetic or evaporative conditions while maintaining an efficient balance between hydraulic supply (vein density) and evaporative demand. To test this, we compared the function and anatomy of leaf hydraulic systems in the leaves of a woody angiosperm (Toona ciliata M. Roem.) grown under high and low irradiance in controlled conditions. Our results confirm that in this species, differential leaf expansion regulates the density of veins and stomata such that leaf hydraulic conductance and stomatal conductance remain proportional. A broader sample of field-grown tree species suggested that differences in leaf venation and stomatal traits induced by sun and shade were not regulated by leaf size in all cases. Our results, however, suggest that leaf size plasticity can provide an efficient way for plants to acclimate hydraulic and stomatal conductances to the contrasting evaporative conditions of sun and shade.     

Evaluation of High‐resolution Melting Curve Analysis as a New Tool for Root‐knot Nematode Diagnostics

In the detection of plant pests, speed and accuracy are vital. High‐resolution melting curve (HRMC) analysis was therefore evaluated as a new tool for the identification of root‐knot nematodes (Meloidogyne spp.). On the basis of the second intergenic spacer (IGS2) region of the ribosomal DNA cistron, Meloidogyne chitwoodi, M. fallax and M. hapla were successfully distinguished from each other and the group of the three tropical species, M. incognita, M. arenaria and M. javanica. Conversely, it was shown that the IGS2 region is not suitable for the tropical species M. enterolobii (senior synonym of M. mayaguensis) as the amplification of multiple fragments of different lengths prevented a reliable HRMC analysis. However, the obtained results provide a proof of principle that HRMC analysis can be a suitable single‐tube assay for fast and accurate root‐knot nematode identification.     

Outcome of SurePath™ cervical samples reported as borderline nuclear change by cytological subtype and high‐risk HPV status

N. Gupta, N. Dudding, J. Crossley, S.J. Payyappilly and J.H.F. Smith
Outcome of SurePath? cervical samples reported as borderline nuclear changes by cytological subtype and high‐risk HPV status Background: The average borderline rate in cervical cytology samples for English laboratories was 3.8% with the range being 2.0–6.8% at the time of the present study, which was undertaken in order to determine the association between different subtypes of borderline nuclear change (BNC), high‐grade cervical intraepithelial neoplasia (CIN) and high‐risk human papillomavirus (hrHPV) status. Materials and methods: Of 68 551 SurePath^TM cervical samples reported in one laboratory over a period of 2 years, 2335 (3.4%) were reported as BNC. hrHPV status was known in 1112 cases (47.6%). The outcome was known only for women with hrHPV‐positive BNC, who were recommended for colposcopy under the National Health Service Cervical Screening Programme sentinel site protocol. Women with hrHPV‐negative BNC were returned to 3‐yearly recall. The cases were subdivided into BNC, high‐grade dyskaryosis cannot be excluded (B‐HG; 105 cases); BNC with koilocytosis (B‐K; 421 cases); BNC with other features of HPV (B‐HPV; 160 cases); and BNC, not otherwise specified (B‐NOS; 426 cases) and were correlated with the histological outcome where available. Results: The study population age ranged from 23 to 65 years. Cases that tested positive for hrHPV by Qiagen HCII assay comprised 78.1%, 81.0%, 73.1% and 67.8% of B‐HG, B‐K, B‐HPV and B‐NOS categories, respectively. CIN2 or worse (CIN2+) was found in 64.6%, 10.0%, 19.7% and 20.1% of hrHPV‐positive cases of B‐HG, B‐K, B‐HPV and B‐NOS, respectively, which was significantly higher in the B‐HG category (P < 0.001) and lower in the B‐K category compared with B‐NOS (p < 0.001) and B‐HPV (p = 0.006) respectively. CIN3+ comprised 55.6%, 6.3%, 26.3% and 19.1% of biopsies in the same categories, respectively. Conclusions: Subtyping BNC is useful, especially B‐K and B‐HG, which, respectively, had the lowest and highest rates of detection of both CIN2+ and CIN3+, confirming that koilocytosis is likely to be associated with transient HPV infection. Women with B‐HG should be referred to colposcopy in the absence of HPV triage.     

Mark Twain: how to fathom the depth of your pet proteome

The present review highlights recent progresses in the technique of combinatorial peptide ligand libraries (CPPL), a methodology that has much to offer for the detection of low- to very-low abundance proteins (nanograms/mL scale and below) in any proteome. In particular, advances in exploration of the urinary, plasma and tissue proteomes are discussed and evaluated. It is shown that when treating biological fluids, such as plasma, with CPLLs, the detection sensitivity, which in the control only reaches 10 ng/mL, can be enhanced to as high as 10 pg/mL, with an increment of sensitivity of three orders of magnitude. The possibility of using CPLLs as a two-dimensional pre-fractionation of any proteome is also evaluated: on the charge axis, CPLL capture can be implemented at no less than three different pH values (4.0, 7.2 and 9.3), thus permitting a capture of proteinaceous analytes bearing a net positive or net negative charge, respectively. When capture is performed in the absence of salts or at high levels of salts (of the Hofmeister series), one can favor the capture of hydrophilic vs. hydrophobic proteins, respectively. This would thus be a genuine 2D protocol, working on orthogonal separation principles (charge vs. hydrophobicity). As the horizon of CPLLs is expanding and its use is exponentially growing, we expect major breakthroughs in, e.g., biomarker discovery, a field that has suffered a decade of failures.