Lack of plasma albumin impairs intravascular lipolysis and explains the associated free fatty acids deficiency and hypertriglyceridemia

<p>Abstract</p> <p>Background</p> <p>Abnormalities in lipid metabolism and transport are hallmarks in analbuminemic Nagase rats (NAR) and humans. Triglyceridemia is nearly 3- to 5-fold higher in female NAR than in control Sprague-Dawley rats (SDR). Also, NAR present with a severe plasma free fatty acid (FFA) deficit. There are conflicting results regarding the mechanisms underlying NAR hypertriglyceridemia.</p> <p>Objective</p> <p>We aimed at investigating whether liver lipogenesis and triglyceride secretion rates into the plasma contribute to the hypertriglyceridemia in NAR. We also studied whether heparin or albumin administration would release the hypothesized lipolysis inhibition in NAR.</p> <p>Methods</p> <p>The incorporation of tritiated water into lipids and the linear accumulation rate of plasma triglycerides after Triton WR1339 injection were the measures of liver lipogenesis and triglyceride secretion rates.</p> <p>Results</p> <p>Lipogenesis (596 ± 40 vs. 929 ± 124 μmol ³H₂O/g/h) and triglyceride (4.25 ± 1.00 vs. 7.04 ± 1.68 mg/dL/min) secretion rates were slower (<it>P </it>≤ 0.05) in fasted NAR than in control SDR. The injection of either heparin or albumin elicited an increase in NAR plasma FFA levels over time. FFA levels reached control levels 90 min after the albumin administration, increasing from 0.36 ± 0.05 to 1.34 ± 0.16 mEq/L (<it>P </it>≤ 0.05). These results indicate that the lack of plasma albumin inhibits intravascular lipolysis and causes the FFA deficit observed in NAR.</p> <p>Conclusion</p> <p>NAR hepatic triglyceride synthesis and output do not contribute to NAR hypertriglyceridemia. We propose that the lack of albumin diminishes intravascular lipolysis which reduces the plasma triglyceride removal rate and explain both NAR hypertriglyceridemia and FFA deficiency.</p

Challenging metastatic breast cancer with the natural defensin PvD1

© The Royal Society of Chemistry 2017Metastatic breast cancer is a very serious life threatening condition that poses many challenges for the pharmaceutical development of effective chemotherapeutics. As the therapeutics targeted to the localized masses in breast improve, metastatic lesions in the brain slowly increase in their incidence compromising successful treatment outcomes overall. The blood-brain-barrier (BBB) is one important obstacle for the management of breast cancer brain metastases. New therapeutic approaches are in demand for overcoming the BBB's breaching by breast tumor cells. In this work we demonstrate the potential dual role of a natural antimicrobial plant defensin, PvD1: it interferes with the formation of solid tumors in the breast and concomitantly controls adhesion of breast cancer cells to human brain endothelial cells. We have used a combination of techniques that probe PvD1's effect at the single cell level and reveal that this peptide can effectively damage breast tumor cells, leaving healthy breast and brain cells unaffected. Results suggest that PvD1 quickly internalizes in cancer cells but remains located in the membrane of normal cells with no significant damage to its structure and biomechanical properties. These interactions in turn modulate cell adhesiveness between tumor and BBB cells. PvD1 is a potential template for the design of innovative pharmacological approaches for metastatic breast cancer treatment: the manipulation of the biomechanical properties of tumor cells that ultimately prevent their attachment to the BBB.This work was supported by a grant from Laço (Portugal). The authors thank Fundação para a Ciência e a Tecnologia (FCT I.P., Portugal) for funding—PTDC/BBB-BQB/1693/2014 and LISBOA-01-0145-FEDER-007391, project co-financed by FEDER through POR Lisboa 2020 - Programa Operacional Regional de Lisboa, Portugal 2020, and by Fundação para a Ciência e a Tecnologia, and also acknowledge financial support from the Brazilian agencies CNPq, CAPES, and FAPERJ (E-26/203.090/2016; E-26/202.132/2015). Tiago N. Figueira, Filipa D. Oliveira and Diana Gaspar acknowledge FCT I.P. for fellowships SFRH/ BD/5283/2013, PD/BD/135046/2017 and SFRH/BPD/109010/2015. Marie Skłodowska-Curie Research and Innovation Staff Exchange (RISE) is also acknowledged for funding: call H2020-MSCA-RISE-2014, Grant agreement 644167, 2015–2019. Prof. Teresa R. Pacheco (FMUL) and Prof. Alexandra Brito (FFUL) are acknowledged for providing the human breast cell lines and HBMEC primary culture, respectively.info:eu-repo/semantics/publishedVersio

Plant defensin PvD1 modulates the membrane composition of breast tumour-derived exosomes

This journal is © The Royal Society of Chemistry 2019One of the most important causes of failure in tumour treatment is the development of resistance to therapy. Cancer cells can develop the ability to lose sensitivity to anti-neoplastic drugs during reciprocal crosstalk between cells and their interaction with the tumour microenvironment (TME). Cell-to-cell communication regulates a cascade of interdependent events essential for disease development and progression and can be mediated by several signalling pathways. Exosome-mediated communication is one of the pathways regulating these events. Tumour-derived exosomes (TDE) are believed to have the ability to modulate TMEs and participate in multidrug resistance mechanisms. In this work, we studied the effect of the natural defensin from common bean, PvD1, on the formation of exosomes by breast cancer MCF-7 cells, mainly the modulatory effect it has on the level of CD63 and CD9 tetraspanins. Moreover, we followed the interaction of PvD1 with biological and model membranes of selected composition, by biophysical and imaging techniques. Overall, the results show that PvD1 induces a dual effect on MCF-7 derived exosomes: the peptide attenuates the recruitment of CD63 and CD9 to exosomes intracellularly and binds to the mature exosomes in the extracellular environment. This work uncovers the exosomemediated anticancer action of PvD1, a potential nutraceutical agent.The authors thank Fundação para a Ciência e a Tecnologia (FCT I.P., Portugal) for funding – PTDC/BBB-BQB/1693/2014, and also acknowledge financial support from the Brazilian agencies CNPq, CAPES, and FAPERJ (E-26/203.090/2016; E-26/202.132/2015). Julia Skalska, Filipa D. Oliveira, Tiago N. Figueira and Diana Gaspar acknowledge FCT I.P. for fellowships PD/BD/114177/2016, PD/BD/135046/2017, SFRH/BD/5283/2013 and SFRH/BPD/109010/2015 respectively. Marie Skłodowska-Curie Research and Innovation Staff Exchange (RISE) is also acknowledged for funding: call H2020-MSCA-RISE-2014, Grant agreement 644167, 2015–2019.info:eu-repo/semantics/publishedVersio

Safranine As A Fluorescent Probe For The Evaluation Of Mitochondrial Membrane Potential In Isolated Organelles And Permeabilized Cells.

The mitochondrial electrical membrane potential (Δψ) is the main component of the proton motive force (Δp) generated across the inner mitochondrial membrane during electron flow through the respiratory chain. Among the techniques available to assess Δψ, methods that rely on the spectrophotofluorometric responses of dyes are widely employed for whole suspensions of isolated mitochondria or permeabilized cells. Safranine is one of the dyes currently used most often for this purpose. Safranine is a lipophilic cationic dye that undergoes optical shifts upon its potential-dependent distribution between the external medium and the intramitochondrial compartment and on its stacking to inner mitochondrial membrane anionic sites. The association between the optical changes of safranine and the membrane potential allows unknown Δψ values to be estimated from an equation describing their relationship. Here, we describe the use of safranine as a fluorescent indicator of Δψ in isolated mitochondria and digitonin-permeabilized cells. We present suitable conditions to employ safranine as a Δψ indicator.810103-1

AEROBIC FITNESS LEVEL TYPICAL OF ELITE ATHLETES IS NOT ASSOCIATED WITH EVEN FASTER VO2 KINETICS DURING CYCLING EXERCISE

The aim of this study was to address the question if the VO2 kinetics is further improved as the aerobic training status increases from trained to elite level athletes. Maximal oxygen uptake (VO2max), work-rate associated to VO2max (IVO2max) and VO2 kinetics of moderate (Mod) and maximal exercise (Max) were determined in fifty- five subjects. Then, they were assigned into three groups: low (LF), intermediate (IF) and high (HF) aerobic fitness level. In average, the VO2max of LF, IF and HF groups were, respectively, 36.0 ± 3.1, 51.1 ± 4.5 and 68.1 ± 3.9 ml·kg·min-1 (p < 0.05 among each other). VO2 kinetics mean response time of both exercise intensities were significantly faster (p < 0.05) in HF (Mod, 27.5 ± 5.5 s; Max, 32.6 ± 8.3 s) and IF (Mod, 25.0 ± 3.1 s; Max, 42.6 ± 10.4 s) when compared to LF (Mod, 35.7 ± 7.9 s; Max: 57.8 ± 17.8 s). We can conclude that VO2 kinetics is improved as the fitness level is increased from low to intermediate but not further improved as the aerobic fitness level increases from intermediate to high

The interaction of antibodies with lipid membranes unraveled by fluorescence methodologies

© 2014 Elsevier B.V. All rights reserved.The interest and investment in antibody therapies has reached an overwhelming scale in the last decade. Yet, little concern has been noticed among the scientific community to unravel important interactions of antibodies with biological structures other than their respective epitopes. Lipid membranes are particularly relevant in this regard as they set the stage for protein–protein recognition, a concept potentially inclusive of antibody–antigen recognition. Fluorescence techniques allow experimental monitoring of protein partition between aqueous and lipid phases, deciphering events of adsorption, insertion and diffusion. This review focuses on the available fluorescence spectroscopy methodologies directed to the study of antibody-membrane interaction

EFFECTS OF GENDER ON STROKE RATES, CRITICAL SPEED AND VELOCITY OF A 30-MIN SWIM IN YOUNG SWIMMERS

Our objective was to analyze the effect of gender on the relationship between stroke rates corresponding to critical speed (SRCS) and maximal speed of 30 min (SRS30) in young swimmers. Twenty two males (GM1) (Age = 15.4 ± 2.1 yr., Body mass = 63.7 ± 12.9 kg, Stature = 1.73 ± 0.09 m) and fourteen female (GF) swimmers (Age = 15.1 ± 1.6 yr., Body mass = 58.3 ± 8.8 kg, Stature = 1.65 ± 0.06 m) were studied. A subset of males (GM2) was matched to the GF by their velocity for a 30 min swim (S30). The critical speed (CS) was determined through the slope of the linear regression line between the distances (200 and 400 m) and participant's respective times. CS was significantly higher than S30 in males (GM1 - 1.25 and 1.16 and GM2 - 1.21 and 1.12 m·s-1) and females (GF - 1.15 and 1.11 m·s-1). There was no significant difference between SRCS and SRS30 in males (GM1 - 34.16 and 32.32 and GM2 - 34.67 and 32.46 cycle·s-1, respectively) and females (GF - 34.18 and 33.67 cycle·s-1, respectively). There was a significant correlation between CS and S30 (GM1 - r = 0.89, GF - r = 0.94 and GM2 - r = 0.90) and between SRCS and SRS30 (GM1 - r = 0.89, GF - r = 0.80 and GM2 - r = 0.88). Thus, the relationship between SRCS and SRS30 is not influenced by gender, in swimmers with similar and different aerobic capacity level

Influence of exercise mode and maximal lactate-steady-state concentration on the validity of OBLA to predict maximal lactate-steady-state in active individuals

The aim of this study was to analyze the effects of exercise mode on the validity of onset of blood lactate accumulation (OBLA-3.5-mM fixed blood lactate concentration) to predict the work-rate at maximal lactate steady state (MLSSwork-rate). Eleven recreationally active mates (21.3 +/- 2.9 years, 72.8 +/- 6.7 kg, 1.78 +/- 0.1 m) performed randomly incremental tests to determine OBLA (stage duration of 3 min), and 2 to 4 constants work-rate exercise tests to directly determine maximal lactate steady state parameters on a cycle-ergometer and treadmill. For both exercise modes, the OBLA was significantly correlated to MLSSwork-rate, (cycling: r = 0.81 p = 0.002; running: r = 0.94, p < 0.001). OBLA (156.2 +/- 41.3 W) was lower than MLSSwork-rate (179.6 +/- 26.4 W) during cycling exercise (p = 0.007). However, for running exercise, there was no difference between OBLA (3.2 +/- 0.6 m s(-1)) and MLSSwork-rate (3.1 +/- 0.4 m s(-1)). The difference between OBLA and MLSSworkrate on the cycle-ergometer (r = 0.86; p < 0.001) and treadmill (r = 0.64; p = 0.048) was significantly related to the specific MLSS. We can conclude that the validity of OBLA on predicting MLSSwork-rate is dependent on exercise mode and that its disagreement is related to individual variations in MLSS. (C) 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved

Effects of gender on stroke rates, critical speed and velocity of a 30-min swim in young swimmers

Our objective was to analyze the effect of gender on the relationship between stroke rates corresponding to critical speed (SRCS) and maximal speed of 30 min (SRS30) in young swimmers. Twenty two males (GM1) (Age = 15.4 ± 2.1 yr., Body mass = 63.7 ± 12.9 kg, Stature = 1.73 ± 0.09 m) and fourteen female (GF) swimmers (Age = 15.1 ± 1.6 yr., Body mass = 58.3 ± 8.8 kg, Stature = 1.65 ± 0.06 m) were studied. A subset of males (GM2) was matched to the GF by their velocity for a 30 min swim (S30). The critical speed (CS) was determined through the slope of the linear regression line between the distances (200 and 400 m) and participant's respective times. CS was significantly higher than S30 in males (GM1 - 1.25 and 1.16 and GM2 - 1.21 and 1.12 m·s-1) and females (GF - 1.15 and 1.11 m·s-1). There was no significant difference between SRCS and SRS30 in males (GM1 - 34.16 and 32.32 and GM2 - 34.67 and 32.46 cycle·s-1, respectively) and females (GF - 34.18 and 33.67 cycle·s-1-1, respectively). There was a significant correlation between CS and S30 (GM1 - r = 0.89, GF - r = 0.94 and GM2 - r = 0.90) and between SRCS and SRS30 (GM1 - r = 0.89, GF - r = 0.80 and GM2 - r = 0.88). Thus, the relationship between SRCS and SRS30 is not influenced by gender, in swimmers with similar and different aerobic capacity levels. ©Journal of Sports Science and Medicine (2007)