Synergy of photoacoustic and fluorescence flow cytometry of circulating cells with negative and positive contrasts

In vivo photoacoustic (PA) and fluorescence flow cytometry were previously applied separately using pulsed and continuous wave lasers respectively, and positive contrast detection mode only. This paper introduces a real‐time integration of both techniques with positive and negative contrast modes using only pulsed lasers. Various applications of this new tool are summarized, including detection of liposomes loaded with Alexa‐660 dye, red blood cells labeled with Indocyanine Green, B16F10 melanoma cells co‐expressing melanin and green fluorescent protein (GFP), C8161‐GFP melanoma cells targeted by magnetic nanoparticles, MTLn3 adenocarcinoma cells expressing novel near‐infrared iRFP protein, and quantum dot‐carbon nanotube conjugates. Negative contrast flow cytometry provided label‐free detection of low absorbing or weakly fluorescent cells in blood absorption and autofluorescence background, respectively. The use of pulsed laser for time‐resolved discrimination of objects with long fluorescence lifetime (e.g., quantum dots) from shorter autofluorescence background (e.g., blood plasma) is also highlighted in this paper. The supplementary nature of PA and fluorescence detection increased the versatility of the integrated method for simultaneous detection of probes and cells having various absorbing and fluorescent properties, and provided verification of PA data using a more established fluorescence based technique. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

PARP Inhibition Sensitizes to Low Dose-Rate Radiation TMPRSS2-ERG Fusion Gene-Expressing and PTEN-Deficient Prostate Cancer Cells

Exposure to genotoxic agents, such as irradiation produces DNA damage, the toxicity of which is augmented when the DNA repair is impaired. Poly (ADP-ribose) polymerase (PARP) inhibitors were found to be “synthetic lethal” in cells deficient in BRCA1 and BRCA2 that impair homologous recombination. However, since many tumors, including prostate cancer (PCa) rarely have on such mutations, there is considerable interest in finding alternative determinants of PARP inhibitor sensitivity. We evaluated the effectiveness of radiation in combination with the PARP inhibitor, rucaparib in PCa cells. The combination index for clonogenic survival following radiation and rucaparib treatments revealed synergistic interactions in a panel of PCa cell lines, being strongest for LNCaP and VCaP cells that express ETS gene fusion proteins. These findings correlated with synergistic interactions for senescence activation, as indicated by β--galactosidase staining. Absence of PTEN and presence of ETS gene fusion thus facilitated activation of senescence, which contributed to decreased clonogenic survival. Increased radiosensitivity in the presence of rucaparib was associated with persistent DNA breaks, as determined by χ-H2AX, p53BP1, and Rad51 foci. VCaP cells, which harbor the TMPRSS2-ERG gene fusion and PC3 cells that stably express a similar construct (fusion III) showed enhanced sensitivity towards rucaparib, which, in turn, increased the radiation response to a similar extent as the DNA-PKcs inhibitor NU7441. Rucaparib radiosensitized PCa cells, with a clear benefit of low dose-rate radiation (LDR) administered over a longer period of time that caused enhanced DNA damage. LDR mimicking brachytherapy, which is used successfully in the clinic, was most effective when combined with rucaparib by inducing persistent DNA damage and senescence, leading to decreased clonogenic survival. This combination was most effective in the presence of the TMPRSS2-ERG and in the absence of PTEN, indicating clinical potential for brachytherapy in patients with intermediate and high risk PCa.     

Circulating Endothelial Progenitor Cell and Platelet Microparticle Impact on Platelet Activation in Hypertension Associated with Hypercholesterolemia

Aim

The purpose of this project was to evaluate the influence of circulating endothelial progenitor cells (EPCs) and platelet microparticles (PMPs) on blood platelet function in experimental hypertension associated with hypercholesterolemia.

Methods

Golden Syrian hamsters were divided in six groups: (i) control, C; (ii) hypertensive-hypercholesterolemic, HH; (iii) ‘prevention’, HHin-EPCs, HH animals fed a HH diet and treated with EPCs; (iv) ‘regression’, HHfin-EPCs, HH treated with EPCs after HH feeding; (v) HH treated with PMPs, HH-PMPs, and (vi) HH treated with EPCs and PMPs, HH-EPCs-PMPs.

Results

Compared to HH group, the platelets from HHin-EPCs and HHfin-EPCs groups showed a reduction of: (i) activation, reflected by decreased integrin 3β, FAK, PI3K, src protein expression; (ii) secreted molecules as: SDF-1, MCP-1, RANTES, VEGF, PF4, PDGF and (iii) expression of pro-inflammatory molecules as: SDF-1, MCP-1, RANTES, IL-6, IL-1β; TFPI secretion was increased. Compared to HH group, platelets of HH-PMPs group showed increased activation, molecules release and proteins expression. Compared to HH-PMPs group the combination EPCs with PMPs treatment induced a decrease of all investigated platelet molecules, however not comparable with that recorded when EPC individual treatment was applied.

Conclusion

EPCs have the ability to reduce platelet activation and to modulate their pro-inflammatory and anti-thrombogenic properties in hypertension associated with hypercholesterolemia. Although, PMPs have several beneficial effects in combination with EPCs, these did not improve the EPC effects. These findings reveal a new biological role of circulating EPCs in platelet function regulation, and may contribute to understand their cross talk, and the mechanisms of atherosclerosis.     

Adsorption of low-density lipoprotein,its oxidation,and subsequent binding of specific recombinant antibodies: An in situ ellipsometric study

Background

Low-density lipoprotein (LDL) particles accumulate in the arterial wall and become oxidized during atherogenesis, leading to the formation of atherosclerotic plaques. The major protein of the LDL particle, apolipoprotein B-100 (apoB-100), becomes fragmented during oxidation and a target for the immune system.

Methods

In this study we used in situ ellipsometry to monitor the adsorption of LDL to solid silica surfaces and the effects of oxidation on the structure of the adsorbed LDL layer. We additionally investigated the binding kinetics of two recombinant human antibodies with different specificities recognizing epitopes of apoB-100 in surface-bound native and CuCl₂-oxidized LDL (oxLDL). The latter process was studied by adsorbing LDL and then adding the antibody and CuCl₂ while continuously monitoring adsorbed amount and the thickness of the film. The molar ratios between the antibodies and surface-bound LDL and oxLDL were calculated from these data.

Results

Our results indicate that oxidation of surface-bound LDL induces swelling of the layer, accompanied by a slight desorption. We further found that both antibodies were able to recognize LDL and oxLDL in its adsorbed orientation. Quantitative information was obtained on the number of available binding sites on surface-bound LDL and oxLDL for these two antibodies.

General significance

Using ellipsometry for real-time monitoring of adsorption, in situ oxidation of LDL and binding of specific recombinant antibodies to surface-bound LDL, will open up possibilities to map different conformations and orientations of LDL in the adsorbed state.     

All size classes of soil fauna and litter quality control the acceleration of litter decay in its home environment

There is increasing evidence that litter decomposition is faster beneath the plant species it was derived from, an effect called home‐field advantage (HFA). Adaptation of soil biota to decompose the litter that they encounter most often has been proposed as the main mechanism to explain HFA. However, there is little direct evidence supporting this assumption and the contribution of different decomposer groups to the HFA is unknown. Furthermore, the large observed variation in the strength of the HFA may be linked to litter quality, with increasing HFA for more recalcitrant substrates. To test the relationship between HFA, litter quality and soil fauna, we performed a field litter bag experiment, with different mesh sizes and reciprocal litter transplants, across a successional gradient varying in litter quality inputs and soil fauna composition. The results show that the HFA was stronger in sites dominated by more recalcitrant litter inputs and provide evidence that a range of soil fauna size classes contribute to this effect. Our findings help explain the lack of HFA in ecosystems with simple litters and in studies where experimental artefacts (e.g. fine mesh sizes) affect the contribution from certain classes of soil fauna.     

Plant diversity surpasses plant functional groups and plant productivity as driver of soil biota in the long term

Background

One of the most significant consequences of contemporary global change is the rapid decline of biodiversity in many ecosystems. Knowledge of the consequences of biodiversity loss in terrestrial ecosystems is largely restricted to single ecosystem functions. Impacts of key plant functional groups on soil biota are considered to be more important than those of plant diversity; however, current knowledge mainly relies on short-term experiments.

Methodology/Principal Findings

We studied changes in the impacts of plant diversity and presence of key functional groups on soil biota by investigating the performance of soil microorganisms and soil fauna two, four and six years after the establishment of model grasslands. The results indicate that temporal changes of plant community effects depend on the trophic affiliation of soil animals: plant diversity effects on decomposers only occurred after six years, changed little in herbivores, but occurred in predators after two years. The results suggest that plant diversity, in terms of species and functional group richness, is the most important plant community property affecting soil biota, exceeding the relevance of plant above- and belowground productivity and the presence of key plant functional groups, i.e. grasses and legumes, with the relevance of the latter decreasing in time.

Conclusions/Significance

Plant diversity effects on biota are not only due to the presence of key plant functional groups or plant productivity highlighting the importance of diverse and high-quality plant derived resources, and supporting the validity of the singular hypothesis for soil biota. Our results demonstrate that in the long term plant diversity essentially drives the performance of soil biota questioning the paradigm that belowground communities are not affected by plant diversity and reinforcing the importance of biodiversity for ecosystem functioning.     

Persistent sympathoexcitation long after submaximal exercise in subjects with and without coronary artery disease

There is an increased risk of cardiac events after exercise, which may, in part, be mediated by the sympathoexcitation that accompanies exercise. The duration and extent of this sympathoexcitation following moderate exercise is unknown, particularly in those with coronary artery disease (CAD). Twenty control subjects (mean age, 51 years) and 89 subjects with CAD (mean age, 58 years) underwent two 16-min bicycle exercise sessions followed by 30-45 min of recovery. Session 1 was performed under physiological conditions to peak workloads of 50-100 W. In session 2, parasympathetic blockade with atropine (0.04 mg/kg) was achieved at end exercise at the same workload as session 1. RR interval was continually recorded, and plasma catecholamines were measured at rest and selected times during exercise and recovery. Parasympathetic effect, measured as the difference in RR interval with and without atropine, did not differ between controls and CAD subjects in recovery. At 30 and 45 min of recovery, RR intervals were 12% and 9%, respectively, shorter than at rest. At 30 and 45 min of recovery, plasma norepinephrine levels were 15% and 12%, respectively, higher than at rest. A brief period of moderate exercise is associated with a prolonged period of sympathoexcitation extending >45 min into recovery and is quantitatively similar among control subjects and subjects with CAD, with or without left ventricular dysfunction. Parasympathetic reactivation occurs early after exercise and is also surprisingly quantitatively similar in controls and subjects with CAD. The role of these autonomic changes in precipitating cardiac events requires further evaluation.     

Decreased paraoxonase 2 enzymatic activity in monocyte/macrophages cells. A comparative in vivo and in vitro study for diabetes

Aim: To investigate peripheral blood monocytes/macrophages (Mo/M?) paraoxonase 2 (PON2) in diabetes and the factors modulating its activity.

Methods: One hundred and eighteen patients with newly diagnosed uncomplicated type 2 diabetes mellitus were compared regarding clinical, biochemical and oxidative stress parameters with 80 healthy subjects. The capacity of the peripheral blood mononuclear cells (PBMNC) to release pro-oxidants and to neutralise them was determined by measuring the respiratory burst (RB) and the intracellular antioxidant enzyme PON2. In vitro experiments were conducted on a differentiated monocytes cell line (dU937) that was exposed to serum deprivation followed by addition of isolated lipoproteins (VLDL or LDL).

Results: Paraoxonase 2 activity in Mo/M? was significantly lower in type 2 diabetes patients (0.042?±?0.044 vs 0.165?±?0.133U lactonase activity/mg protein in controls, p?1c) and insulin resistance (HOMA-IR). In multivariate regression models, 15–34% of the PON2 variance was explained by diabetes. The in vitro addition of VLDL normalised the RB of serum deprived dU937 cells, S? (to 82?±?18% of the cells incubated with serum, S+) and PON2 activity (from 0.524?±?0.061 in S???to 0.298?±?0.048?U/mg protein). In contrast, when LDL was added, the RB remained lower (61?±?12% of S+, p?=?.03) and PON2 higher (0.580?±?0.030?U/mg protein, p?=?.003).

Conclusions: The decrease in monocyte/macrophage PON2 enzymatic activity observed in type 2 diabetes cannot be totally explained by abdominal obesity and insulin resistance. The underlying molecular mechanisms need to be identified.