Publications by authors named "Jaime Franco"

23 Publications

  • Page 1 of 1

The metabesity factor HMG20A potentiates astrocyte survival and reactive astrogliosis preserving neuronal integrity.

Theranostics 2021 12;11(14):6983-7004. Epub 2021 May 12.

Andalusian Center of Molecular Biology and Regenerative Medicine-CABIMER, Junta de Andalucía-University of Pablo de Olavide-University of Seville-CSIC, Seville, Spain.

We recently demonstrated that the 'Metabesity' factor HMG20A regulates islet beta-cell functional maturity and adaptation to physiological stress such as pregnancy and pre-diabetes. HMG20A also dictates central nervous system (CNS) development via inhibition of the LSD1-CoREST complex but its expression pattern and function in adult brain remains unknown. Herein we sought to determine whether HMG20A is expressed in the adult CNS, specifically in hypothalamic astrocytes that are key in glucose homeostasis and whether similar to islets, HMG20A potentiates astrocyte function in response to environmental cues. HMG20A expression profile was assessed by quantitative PCR (QT-PCR), Western blotting and/or immunofluorescence in: 1) the hypothalamus of mice exposed or not to either a high-fat diet or a high-fat high-sucrose regimen, 2) human blood leukocytes and adipose tissue obtained from healthy or diabetic individuals and 3) primary mouse hypothalamic astrocytes exposed to either high glucose or palmitate. RNA-seq and cell metabolic parameters were performed on astrocytes treated or not with a siHMG20A. Astrocyte-mediated neuronal survival was evaluated using conditioned media from siHMG20A-treated astrocytes. The impact of ORY1001, an inhibitor of the LSD1-CoREST complex, on HMG20A expression, reactive astrogliosis and glucose metabolism was evaluated and in high-fat high-sucrose fed mice. We show that is predominantly expressed in hypothalamic astrocytes, the main nutrient-sensing cell type of the brain. HMG20A expression was upregulated in diet-induced obesity and glucose intolerant mice, correlating with increased transcript levels of and indicative of inflammation and reactive astrogliosis. transcript levels were also increased in adipose tissue of obese non-diabetic individuals as compared to obese diabetic patients. HMG20A silencing in astrocytes resulted in repression of inflammatory, cholesterol biogenesis and epithelial-to-mesenchymal transition pathways which are hallmarks of reactive astrogliosis. Accordingly, HMG20A depleted astrocytes exhibited reduced mitochondrial bioenergetics and increased susceptibility to apoptosis. Neuron viability was also hindered in HMG20A-depleted astrocyte-derived conditioned media. ORY1001 treatment rescued expression of reactive astrogliosis-linked genes in HMG20A ablated astrocytes while enhancing cell surface area, GFAP intensity and STAT3 expression in healthy astrocytes, mimicking the effect of HMG20A. Furthermore, ORY1001 treatment protected against obesity-associated glucose intolerance in mice correlating with a regression of hypothalamic HMG20A expression, indicative of reactive astrogliosis attenuation with improved health status. HMG20A coordinates the astrocyte polarization state. Under physiological pressure such as obesity and insulin resistance that induces low grade inflammation, HMG20A expression is increased to induce reactive astrogliosis in an attempt to preserve the neuronal network and re-establish glucose homeostasis. Nonetheless, a chronic metabesity state or functional mutations will result in lower levels of HMG20A, failure to promote reactive astrogliosis and increase susceptibility of neurons to stress-induced apoptosis. Such effects could be reversed by ORY1001 treatment both and , paving the way for a new therapeutic approach for Type 2 Diabetes Mellitus.
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http://dx.doi.org/10.7150/thno.57237DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8171100PMC
May 2021

Novel distamycin analogues that block the cell cycle of African trypanosomes with high selectivity and potency.

Eur J Med Chem 2020 Mar 8;189:112043. Epub 2020 Jan 8.

Group Redox Biology of Trypanosomes, Institut Pasteur de Montevideo, Montevideo, Uruguay. Electronic address:

Polyamides-based compounds related to the Streptomycetal distamycin and netropsin are potent cytostatic molecules that bind to AT-rich regions of the minor groove of the DNA, hence interfering with DNA replication and transcription. Recently, derivatives belonging to this scaffold have been reported to halt the proliferation of deadly African trypanosomes by different and unrelated mechanisms. Here we describe the synthesis and preliminary characterization of the anti-trypanosomal mode of action of new potent and selective distamycin analogues. Two tri-heterocyclic derivatives containing a central N-methyl pyrrole ring (16 and 17) displayed high activity (EC < 20 nM) and selectivity (selectivity index >5000 with respect to mammalian macrophages) against the infective form of T. brucei. Both compounds caused cell cycle arrest by blocking the replication of the mitochondrial DNA but without affecting its integrity. This mode of action clearly differs from that reported for classical minor groove binder (MGB) drugs, which induce the degradation of the mitochondrial DNA. In line with this, in vitro assays suggest that 16 and 17 have a comparatively lower affinity for different template DNAs than the MGB drug diminazene. Therapeutic efficacy studies and stability assays suggest that the pharmacological properties of the hits should be optimized. The compounds can be rated as excellent scaffolds for the design of highly potent and selective anti-T. brucei agents.
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http://dx.doi.org/10.1016/j.ejmech.2020.112043DOI Listing
March 2020

Synthesis of bicyclic 1,4-thiazepines as novel anti- agents.

Medchemcomm 2019 Aug 11;10(8):1481-1487. Epub 2019 Jun 11.

Laboratorio de Química Farmacéutica , Departamento de Química Orgánica , Facultad de Química , Universidad de la República , Montevideo , Uruguay . Email: ; Email:

1,4-Thiazepines derivatives are pharmacologically important heterocycles with different applications in medicinal chemistry. In the present work, we describe the preparation of new bicyclic thiazolidinyl-1,4-thiazepines by reaction between azadithiane compounds and Michael acceptors. The reaction scope was explored and the yields were optimized. The activity of the new compounds was evaluated against and as anthelmintic models and The most active compound was , showing an EC = 2.8 ± 0.7 μM against and a selectivity index >71.
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http://dx.doi.org/10.1039/c9md00064jDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6786244PMC
August 2019

Differential Interactome and Innate Immune Response Activation of Two Structurally Distinct Misfolded Protein Oligomers.

ACS Chem Neurosci 2019 08 2;10(8):3464-3478. Epub 2019 Aug 2.

Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER) - Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC) , Universidad Pablo de Olavide , 41092 Seville , Spain.

The formation of misfolded protein oligomers during early stages of amyloid aggregation and the activation of neuroinflammatory responses are two key events associated with neurodegenerative diseases. Although it has been established that misfolded oligomers are involved in the neuroinflammatory process, the links between their structural features and their functional effects on the immune response remain unknown. To explore such links, we took advantage of two structurally distinct soluble oligomers (type A and B) of protein HypF-N and compared the elicited microglial inflammatory responses. By using confocal microscopy, protein pull-down, and high-throughput mass spectrometry, we found that, even though both types bound to a common pool of microglial proteins, type B oligomers-with a lower solvent-exposed hydrophobicity-showed enhanced protein binding, correlating with the observed inflammatory response. Furthermore, the interactome associated with inflammatory-mediated neurodegeneration revealed previously unidentified receptors and signaling molecules likely to be involved in the oligomer-elicited innate immune response.
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http://dx.doi.org/10.1021/acschemneuro.9b00088DOI Listing
August 2019

Synthesis and Characterization of Elongated-Shaped Silver Nanoparticles as a Biocompatible Anisotropic SERS Probe for Intracellular Imaging: Theoretical Modeling and Experimental Verification.

Nanomaterials (Basel) 2019 Feb 13;9(2). Epub 2019 Feb 13.

Departamento de Química, UCIBIO, REQUIMTE, Faculdade de Ciências, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.

Progress in the field of biocompatible SERS nanoparticles has promising prospects for biomedical applications. In this work, we have developed a biocompatible Raman probe by combining anisotropic silver nanoparticles with the dye rhodamine 6G followed by subsequent coating with bovine serum albumin. This nanosystem presents strong SERS capabilities in the near infrared (NIR) with a very high (2.7 × 10⁷) analytical enhancement factor. Theoretical calculations reveal the effects of the electromagnetic and chemical mechanisms in the observed SERS effect for this nanosystem. Finite element method (FEM) calculations showed a considerable near field enhancement in NIR. Using density functional quantum chemical calculations, the chemical enhancement mechanism of rhodamine 6G by interaction with the nanoparticles was probed, allowing us to calculate spectra that closely reproduce the experimental results. The nanosystem was tested in cell culture experiments, showing cell internalization and also proving to be completely biocompatible, as no cell death was observed. Using a NIR laser, SERS signals could be detected even from inside cells, proving the applicability of this nanosystem as a biocompatible SERS probe.
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http://dx.doi.org/10.3390/nano9020256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6409692PMC
February 2019

Cell tracking, survival, and differentiation capacity of adipose-derived stem cells after engraftment in rat tissue.

J Cell Physiol 2018 10 25;233(10):6317-6328. Epub 2018 Apr 25.

Departamento de Bioquímica y Biología Molecular, Universidad de Sevilla, Sevilla, Spain.

Adipose tissue is an important source of adipose derived stem cells (ADSCs). These cells have the potential of being used for certain therapies, in which the main objective is to recover the function of a tissue/organ affected by a disease. In order to contribute to repair of the tissue, these cells should be able to survive and carry out their functions in unfavorable conditions after being transplanted. This process requires a better understanding of the biology involved: such as the time cells remain in the implant site, how long they stay there, and whether or not they differentiate into host tissue cells. This report focuses on these questions. ADSC were injected into three different tissues (substantia nigra, ventricle, liver) and they were tracked in vivo with a dual GFP-Luc reporter system. The results show that ADSCs were able to survive up to 4 months after the engraftment and some of them started showing resident cell tissue phenotype. These results demonstrate their long-term capacity of survival and differentiation when injected in vivo.
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http://dx.doi.org/10.1002/jcp.26439DOI Listing
October 2018

Immunization with α-synuclein/Grp94 reshapes peripheral immunity and suppresses microgliosis in a chronic Parkinsonism model.

Glia 2018 01 11;66(1):191-205. Epub 2017 Oct 11.

Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER. Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain.

Neuroinflammation mediated by chronically activated microglia, largely caused by abnormal accumulation of misfolded α-synuclein (αSyn) protein, is known to contribute to the pathophysiology of Parkinson's disease (PD). In this work, based on the immunomodulatory activities displayed by particular heat-shock proteins (HSPs), we tested a novel vaccination strategy that used a combination of αSyn and Grp94 (HSPC4 or Gp96) chaperone and a murine PD model. We used two different procedures, first, the adoptive transfer of splenocytes from αSyn/Grp94-immunized mice to recipient animals, and second, direct immunization with αSyn/Grp94, to study the effects in a chronic mouse MPTP-model of parkinsonism. We found that both approaches promoted a distinct profile in the peripheral system-supported by humoral and cellular immunity-consisting of a Th1-shifted αSyn-specific response accompanied by an immune-regulatory/Th2-skewed general phenotype. Remarkably, this mixed profile sustained by αSyn/Grp94 immunization led to strong suppression of microglial activation in the substantia nigra and striatum, pointing to a newly described positive effect of anti-αSyn Th1-responses in the context of PD. This strategy is the first to target αSyn and report the suppression of PD-associated microgliosis. Overall, we show that the αSyn/Grp94 combination supports a distinct and long-lasting immune profile in the peripheral system, which has an impact at the CNS level by suppressing chronic microglial activation in an MPTP model of PD. Furthermore, our study demonstrates that reshaping peripheral immunity by vaccination with appropriate misfolding protein/HSP combinations could be highly beneficial as a treatment for neurodegenerative misfolding diseases.
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http://dx.doi.org/10.1002/glia.23237DOI Listing
January 2018

Diglycosyl diselenides alter redox homeostasis and glucose consumption of infective African trypanosomes.

Int J Parasitol Drugs Drug Resist 2017 12 12;7(3):303-313. Epub 2017 Aug 12.

Group Redox Biology of Trypanosomes, Institut Pasteur de Montevideo, Mataojo 2020, 11400 Montevideo, Uruguay. Electronic address:

With the aim to develop compounds able to target multiple metabolic pathways and, thus, to lower the chances of drug resistance, we investigated the anti-trypanosomal activity and selectivity of a series of symmetric diglycosyl diselenides and disulfides. Of 18 compounds tested the fully acetylated forms of di-β-D-glucopyranosyl and di-β-D-galactopyranosyl diselenides (13 and 15, respectively) displayed strong growth inhibition against the bloodstream stage of African trypanosomes (EC 0.54 μM for 13 and 1.49 μM for 15) although with rather low selectivity (SI < 10 assayed with murine macrophages). Nonacetylated versions of the same sugar diselenides proved to be, however, much less efficient or completely inactive to suppress trypanosome growth. Significantly, the galactosyl (15), and to a minor extent the glucosyl (13), derivative inhibited glucose catabolism but not its uptake. Both compounds induced redox unbalance in the pathogen. In vitro NMR analysis indicated that diglycosyl diselenides react with glutathione, under physiological conditions, via formation of selenenylsulfide bonds. Our results suggest that non-specific cellular targets as well as actors of the glucose and the redox metabolism of the parasite may be affected. These molecules are therefore promising leads for the development of novel multitarget antitrypanosomal agents.
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http://dx.doi.org/10.1016/j.ijpddr.2017.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5565762PMC
December 2017

Epigenetic Mechanisms of Gene Regulation in Amyotrophic Lateral Sclerosis.

Adv Exp Med Biol 2017 ;978:255-275

CABIMER, Andalusian Center for Molecular Biology and Regenerative Medicine, Av. Americo Vespucio s/n, 41092, Seville, Spain.

Despite being clinically described 150 years ago, the mechanisms underlying amyotrophic lateral sclerosis (ALS) pathogenesis have not yet been fully understood. Studies in both animal models of ALS and human patients reveal a plethora of alterations such as increased glutamate-mediated excitotoxicity, redox stress, increased apoptosis, defective axonal transport, protein-misfolding events, mitochondrial impairment and sustained unregulated immune responses. Regardless of being sporadic or familiar ALS, the final outcome at the cellular level is the death of upper and lower motor neurons, and once diagnosed, ALS is typically lethal within the next 5 years. There are neither clear biomarkers nor therapeutic or disease-modifying treatments for ALS.Accumulating evidence supports the concept that epigenetic-driven modifications, including altered chromatin remodelling events, RNA editing and non-coding RNA molecules, might shed light into the pathogenic mechanisms underlying sporadic/familiar ALS onset and/or severity to facilitate the identification of effective therapies, early diagnosis and potentially early-stage therapeutic interventions to increase the survival outcome of ALS patients.
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http://dx.doi.org/10.1007/978-3-319-53889-1_14DOI Listing
September 2017

Extracellular TDP-43 aggregates target MAPK/MAK/MRK overlapping kinase (MOK) and trigger caspase-3/IL-18 signaling in microglia.

FASEB J 2017 07 23;31(7):2797-2816. Epub 2017 Mar 23.

Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), University of Seville-Spanish Research Council (CSIC)-University Paplo de Olavide, Seville, Spain; Seville, Spain;

Dysregulated microglial responses are central in neurodegenerative proteinopathies, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar disease (FTLD). Pathologic TDP-43, which is typically found in intracellular inclusions, is a misfolding protein with emerging roles in ALS and FTLD. Recently, TDP-43 species have been found in extracellular fluids of patients; however, the overall implications of TDP-43-mediated signaling linked to neuroinflammation are poorly understood. Our work-the first, to our knowledge, to focus on innate immunity responses to TDP-43 aggregates-shows that such species are internalized by microglia and cause abnormal mobilization of endogenous TDP-43. Exposure to TDP-43 aggregates elicited not only IL-1β, but also NLRP3-dependent and noncanonical IL-18 processing. Moreover, we report a link between TDP-43 and neuronal loss the apoptosis-independent emerging roles of caspase-3 in neurotoxic inflammation. Our results further support the view of noncell autonomous neurodegenerative mechanisms in ALS. Remarkably, we demonstrate that TDP-43 aggregates bind to and colocalize with MAPK/MAK/MRK overlapping kinase (MOK) and show that its phosphorylation status is disrupted. Finally, we show that this TDP-43-caused activation state can be altered by exogenous Hsp27 and Hsp70 chaperones. Our study provides new insight into the immune phenotype, mechanisms, and signaling pathways that operate in microglial neurotoxic activation in ALS.-Leal-Lasarte, M. M., Franco, J. M., Labrador-Garrido, A., Pozo, D., Roodveldt, C. Extracellular TDP-43 aggregates target MAPK/MAK/MRK overlapping kinase (MOK) and trigger caspase-3/IL-18 signaling in microglia.
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http://dx.doi.org/10.1096/fj.201601163RDOI Listing
July 2017

A wearable computing platform for developing cloud-based machine learning models for health monitoring applications.

Annu Int Conf IEEE Eng Med Biol Soc 2016 Aug;2016:5997-6001

Wearable sensors have the potential to enable clinical-grade ambulatory health monitoring outside the clinic. Technological advances have enabled development of devices that can measure vital signs with great precision and significant progress has been made towards extracting clinically meaningful information from these devices in research studies. However, translating measurement accuracies achieved in the controlled settings such as the lab and clinic to unconstrained environments such as the home remains a challenge. In this paper, we present a novel wearable computing platform for unobtrusive collection of labeled datasets and a new paradigm for continuous development, deployment and evaluation of machine learning models to ensure robust model performance as we transition from the lab to home. Using this system, we train activity classification models across two studies and track changes in model performance as we go from constrained to unconstrained settings.
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http://dx.doi.org/10.1109/EMBC.2016.7592095DOI Listing
August 2016

In vitro activity and mode of action of distamycin analogues against African trypanosomes.

Eur J Med Chem 2017 Jan 2;126:776-788. Epub 2016 Dec 2.

Laboratorio de Química Farmacéutica, Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay. Electronic address:

Distamycin, a natural polyamide containing three heterocycle rings with a polar end, has inspired several groups to prepare synthetic analogues, which proved to have anti-trypanosomal and anti-tumoral activity. We describe the synthesis of bi and tri thiazoles amides that harbor different substitutions at their ends and the evaluation of their anti-Trypanosoma brucei activity. The most active compound 10b showed better biological activity (EC 310 nM and selectivity index 16) than the control drug nifurtimox (EC 15 μM and selectivity index 10). Studies on the mode of action show that the parasiticidal activity of 10b originates from disruption of lysosomal homeostasis, which is followed by release of redox active iron, an increase in oxidizing species and collapse of cell membrane integrity. In this respect, our study suggests that non-charged lipophylic distamycins destabilize cell membranes.
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http://dx.doi.org/10.1016/j.ejmech.2016.12.002DOI Listing
January 2017

The 'Omics' of Amyotrophic Lateral Sclerosis.

Trends Mol Med 2016 Jan 13;22(1):53-67. Epub 2015 Dec 13.

Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Spanish National Research Council (CSIC)-Universidad Pablo de Olavide, University of Seville, Seville, Spain; Department of Medical Biochemistry, Molecular Biology, and Immunology, University of Seville Medical School, Seville, Spain. Electronic address:

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disease that primarily affects motor neurons and is accompanied by sustained unregulated immune responses, but without clear indications of the ultimate causative mechanisms. The identification of a diverse array of ALS phenotypes, a series of recently discovered mutations, and the links between ALS and frontotemporal degeneration have significantly increased our knowledge of the disease. In this review we discuss the main features involved in ALS pathophysiology in the context of recent advances in 'omics' approaches, including genomics, proteomics, and others. We emphasize the pressing need to combine clinical imaging with various different parameters taken from omics fields to facilitate early, accurate diagnosis and rational drug design in the treatment of ALS.
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http://dx.doi.org/10.1016/j.molmed.2015.11.001DOI Listing
January 2016

Printing in three dimensions with graphene.

Adv Mater 2015 Mar 21;27(10):1688-93. Epub 2015 Jan 21.

Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, London, SW7 2BP, UK.

Responsive graphene oxide sheets form non-covalent networks with optimum rheological properties for 3D printing. These networks have shear thinning behavior and sufficiently high elastic shear modulus (G') to build self-supporting 3D structures by direct write assembly. Drying and thermal reduction leads to ultra-light graphene-only structures with restored conductivity and elastomeric behavior.
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http://dx.doi.org/10.1002/adma.201405046DOI Listing
March 2015

Long-circulating PEGylated manganese ferrite nanoparticles for MRI-based molecular imaging.

Nanoscale 2015 Feb;7(5):2050-9

BIONAND, Andalusian Centre for Nanomedicine and Biotechnology, BIONAND (Junta de Andalucía-Universidad de Málaga), Parque Tecnológico de Andalucía, Málaga, Spain.

Magnetic resonance based molecular imaging has emerged as a very promising technique for early detection and treatment of a wide variety of diseases, including cancer, neurodegenerative disorders, and vascular diseases. The limited sensitivity and specificity of conventional MRI are being overcome by the development of a new generation of contrast agents, using nanotechnology approaches, with improved magnetic and biological properties. In particular, for molecular imaging, high specificity, high sensitivity, and long blood circulation times are required. Furthermore, the lack of toxicity and immunogenicity together with low-cost scalable production are also necessary to get them into the clinics. In this work, we describe a facile, robust and cost-effective ligand-exchange method to synthesize dual T1 and T2 MRI contrast agents with long circulation times. These contrast agents are based on manganese ferrite nanoparticles (MNPs) between 6 and 14 nm in size covered by a 3 kDa polyethylene glycol (PEG) shell that leads to a great stability in aqueous media with high crystallinity and magnetization values, thus retaining the magnetic properties of the uncovered MNPs. Moreover, the PEGylated MNPs have shown different relaxivities depending on their size and the magnetic field applied. Thus, the 6 nm PEGylated MNPs are characterized by a low r2/r1 ratio of 4.9 at 1.5 T, hence resulting in good dual T1 and T2 contrast agents under low magnetic fields, whereas the 14 nm MNPs behave as excellent T2 contrast agents under high magnetic fields (r2 = 335.6 mM(-1) s(-1)). The polymer core shell of the PEGylated MNPs minimizes their cytotoxicity, and allows long blood circulation times. This combination of cellular compatibility and excellent T2 and r2/r1 values under low magnetic fields, together with long circulation times, make these nanomaterials very promising contrast agents for molecular imaging.
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http://dx.doi.org/10.1039/c4nr05781cDOI Listing
February 2015

Cl-OH ion-exchanging process in chlorapatite (Ca5(PO4)3Cl(x)(OH)(1-x))--a deep insight.

Acta Crystallogr B 2012 Oct 13;68(Pt 5):467-79. Epub 2012 Sep 13.

Instituto de Cerámica de Galicia, Universidad Santiago de Compostela, Santiago de Compostela, Spain.

We have synthesized large chlorapatite [ClAp, Ca(5)(PO(4))(3)Cl(x)(OH)(1-x), where x = 1] single crystals using the molten salt method. We have corroborated that the hexagonal symmetry P6(3)/m describes the crystal structure best, even though the crystals are synthetic and stoichiometric. Moreover, we have performed several thermal treatments on these ClAp crystals, generating new single crystals in the apatite system [Ca(5)(PO(4))(3)Cl(x)(OH)(1-x), where x ≤ 1], where the chloride anions (Cl(-)) were systematically substituted by hydroxyl anions (OH(-)). These new single crystals were methodically characterized by powder and single-crystal X-ray diffraction (SXRD), scanning electron microscopy (SEM), Fourier transform-IR spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDS). We have discovered a previously unreported OH(-) inclusion site substituting the Cl(-) anion during the ion-exchanging process. Finally, we evaluated the atomic rearrangements of the other species involved in the structure. These movements are associated with ionic exchange, which can be justified from an energetic point of view. We also found a novel phase transformation at high temperature. When the crystals are heated over 1753 K the apatite system evolves to a less ordered monoclinic structure, in which the complete loss of the species in the anionic channel (Cl(-), OH(-)) has been confirmed.
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http://dx.doi.org/10.1107/S0108768112019520DOI Listing
October 2012

Synthesis and characterisation of large chlorapatite single-crystals with controlled morphology and surface roughness.

J Mater Sci Mater Med 2012 Oct 18;23(10):2471-82. Epub 2012 Jul 18.

Instituto de Cerámica de Galicia, Universidad Santiago de Compostela, Avda Mestre Mateo S/N, 15706 Santiago de Compostela, Spain.

This work describes the synthesis of chlorapatite single crystals using the molten salt method with CaCl(2) as a flux. By manipulating the processing conditions (amount of flux, firing time and temperature, and cooling rates) it is possible to manipulate the crystal morphology from microscopic fibres to large crystals (up to few millimetre long and ~100 μm thick). The crystal roughness can be controlled to achieve very flat surfaces by changing the melt composition "in situ" at high temperature. The Young modulus and hardness of the crystals are 110 ± 15 and 6.6 ± 1.5 GPa respectively as measured by nanoindentation. Crystal dissolution in Hanks solution starts around the defects. Several in vitro assays were performed; ClAp crystals with different size and shape are biocompatible. Cell apoptosis was very low at 5, 10, and 15 days (Caspase-3) for all the samples. Proliferation (MTT) showed to be influenced by surface roughness and size of the crystals.
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http://dx.doi.org/10.1007/s10856-012-4717-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638812PMC
October 2012

Lamellar spacing in cuboid hydroxyapatite scaffolds regulates bone formation by human bone marrow stromal cells.

Tissue Eng Part A 2011 Jun 2;17(11-12):1615-23. Epub 2011 Apr 2.

Department of Surgery, University of California-San Francisco, San Francisco, California 94143-0807, USA.

Background: A major goal in bone engineering is the creation of large volume constructs (scaffolds and stem cells) that bear load. The scaffolds must satisfy two competing requirements--they need be sufficiently porous to allow nutrient flow to maintain cell viability, yet sufficiently dense to bear load. We studied the effect of scaffold macroporosity on bone formation and scaffold strength, for bone formed by human bone marrow stromal cells.

Methods: Rigid cubical hydroxyapatite/tricalcium phosphate scaffolds were produced by robo-casting. The ceramic line thickness was held constant, but the distance between adjacent lines was either 50, 100, 200, 500, or 1000 μm. Cultured human bone marrow stromal cells were combined with the scaffolds in vitro; transplants were placed into the subcutis of immunodeficient mice. Transplants were harvested 9, 18, 23, 38, or 50 weeks later. Bone formation and scaffold strength were analyzed using histology and compression testing.

Results: Sixty transplants were evaluated. Cortical bone increased with transplant age, and was greatest among 500 μm transplants. In contrast, maximum transplant strength was greatest among 200 μm transplants.

Conclusions: Lamellar spacing within scaffolds regulates the extent of bone formation; 500 μm yields the most new bone, whereas 200 μm yields the strongest transplants.
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http://dx.doi.org/10.1089/ten.TEA.2010.0573DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3098957PMC
June 2011

A reliable and simplified sj/beta-TREC ratio quantification method for human thymic output measurement.

J Immunol Methods 2010 Jan 15;352(1-2):111-7. Epub 2009 Nov 15.

Laboratory of Immunovirology, Biomedicine Institute of Seville, Service of Infectious Diseases, Virgen del Rocio University Hospital, Avda. Manuel Siurot s/n 41013 Seville, Spain.

Current techniques to peripherally assess thymic function are: the signal-joint T-cell receptor excision circle (sj-TREC) level measurement and the naive T cell and CD31+ TREC-rich subset determination. However, all of them are indirect approaches and none could be considered a direct recent thymic emigrant (RTE) marker. To overcome their limitations, Dion et al. (2004) described the sj/beta-TREC ratio that allows the peripheral quantification of the double negative to double positive intrathymic proliferation step. Nevertheless, the protocol described is expensive, sample and time-consuming, thus, limiting its usefulness. In this study, we describe a simplified protocol that reduces from 33 to 9 the amount of PCR reaction needed but maintaining the sensitivity and reproducibility of the original technique. In addition, we corroborated the effectiveness of our technique as an accurate thymic output-related marker by correlating the peripheral sj/beta-TREC ratio with a direct measurement of thymic function as the percentage of double positive thymocytes (r=0.601, p<0.001).
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http://dx.doi.org/10.1016/j.jim.2009.11.007DOI Listing
January 2010

Thymopoiesis in elderly human is associated with systemic inflammatory status.

Age (Dordr) 2009 Jun 31;31(2):87-97. Epub 2009 Jan 31.

Laboratory of Immunovirology, Biomedicine Institute of Seville (IBIS), Service of Infectious Diseases, Virgen del Rocío University Hospital, Manuel Siurot s/n, 41013, Seville, Spain.

Immunosenescence studies of age-related immune system damage focused on clinical lymphopenic situations or androgenic blockade have revealed new insights about adult human immune reconstitution. However, as far as we know, the extent of lymphopoiesis in the thymus of elderly humans remains unclear. To this effect, we have analyzed 65 adult human thymuses (from 36 to 81 years; median age 68.6 years) obtained from patients who underwent cardiac surgery. Our results show a correlation between CD4(+)CD8(+) double-positive (DP) cells and both the age (inverse) and percentage (direct) of peripheral naive T cells, indicating that the thymus is still able to affect the peripheral lymphocyte pool even in the elderly. We also found significant correlation between the degree of thymopoiesis and the inflammation markers, as shown by the inverse correlations between DP and the percentage of neutrophils and IL-6 levels and the percentage of peripheral lymphocytes. Furthermore, in a multivariate linear regression the percentage of DP and IL-7 levels, but not age, were independently associated with the percentage of neutrophils. In conclusion, the thymus maintains, even in the elderly, an active thymopoiesis that rejuvenates the peripheral naive T-cell pool. Moreover, age-related thymopoietic decay is associated with the peripheral inflammation markers.
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http://dx.doi.org/10.1007/s11357-008-9084-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2693727PMC
June 2009

Immunity in HIV-1-infected adults with a previous state of moderate-severe immune-suppression and more than 500 CD4+ T cell after highly active antiretroviral therapy.

J Clin Immunol 2004 Jul;24(4):379-88

Laboratorio de Immuno-Biología Molecular, Hospital General Universitario Gregorio Marañón, C/Doctor Esquerdo 46, 28007 Madrid, Spain.

We evaluated phenotypic and functional parameters of immune restoration of 27 HIV-infected patients on highly active antiretroviral therapy (HAART) (HIV-cases) with HIV-RNA levels below detectable limits at least during 18 months, and CD4+ cell per microliter higher than 500 at the moment of the study and lower than 300 anytime before. These patients were compared with 11 HIV-controls that never had less than 500 CD4+ cell per microliter and 20 healthy-controls (HIV seronegative subjects) in a cross-sectional study. HIV-cases had lower counts of naïve CD4+ than HIV-controls and healthy-controls. HIV-patients (both HIV-cases and HIV-controls) showed higher values of naïve and memory CD8+ counts than healthy-controls. TREC-bearing cell levels were significantly lower in HIV-cases than in healthy-controls. Peripheral blood mononuclear cells (PBMC) cultures, HIV-cases had lower values in proliferation to streptokinase (SK) and tetanus toxin (TT) than in healthy-controls. HIV-cases had lower IFN-gamma and higher IL-5 production with pokeweed than healthy-controls ( P < 0.01). However, IL-5 production of HIV-cases after TT stimulation was lower than in HIV-controls and healthy-controls. Total IgG and IgG1 levels were significantly higher in HIV-cases than in HIV-controls and healthy-controls. Also, IgM levels were significantly higher in HIV-cases than in healthy-controls. Nevertheless, IgG2 levels were significantly lower in HIV-cases and HIV-controls than in healthy-controls. The levels of specific Igs antipneumococcal capsular polysaccharide and TT were significantly lower in HIV-cases than in healthy-controls. HIV-patients with a previous state of severe-moderate immunosuppression normalizing their CD4+ counts have a incomplete immune reconstitution after HAART. Long-term consequences of this subclinical immune deficiency remain to be determined.
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http://dx.doi.org/10.1023/B:JOCI.0000029112.82425.59DOI Listing
July 2004

Endogenous IL-7 is associated with increased thymic volume in adult HIV-infected patients under highly active antiretroviral therapy.

AIDS 2003 May;17(7):947-54

Viral Hepatitis and AIDS Study Group, Virgen del Rocío University Hospital, Seville, Spain.

Objective: Immune reconstitution after highly active antiretroviral therapy (HAART) in HIV-infected patients has led to an increase in the number of new CD4 T lymphocytes. Neolymphopoiesis in the thymus has been proposed as a mechanism in T-cell regeneration. Nevertheless, factors involved in the regeneration of T cells by thymic-dependent pathways in HIV-infected patients under HAART are still unknown and might be of relevance in HIV infection. The aim of this work was to study the role of IL-7 in the thymic rebound of HIV-infected adults under HAART.

Design: To study the association between IL-7 and thymic function-related markers, these variables were measured in 49 antiretroviral-naive HIV-infected patients at baseline and at weeks 12, 24, 36 and 48 of treatment.

Methods: Thymic function-related markers: thymic volume, naive phenotype, and T-cell receptor excision circles (TREC) bearing-cells, were evaluated by computed tomography, flow cytometry, and quantitative polymerase chain reaction, respectively. IL-7 levels were evaluated using a high sensitivity colorimetric enzyme-linked immunosorbent assay.

Results: At baseline, we found an inverse correlation between IL-7 levels and thymic function-associated parameters: thymic volume, naive T cells and TREC-bearing cells. After 48 weeks of therapy increased levels of thymic function-related markers along with a significant decrease in IL-7 levels were found. IL-7 levels at baseline were the only independently associated variable with respect to changes in thymic volume at weeks 12, 24 and 48 of follow-up.

Conclusion: These data suggest that IL-7 plays an important role in thymic rebound in adult HIV-infected patients under HAART.
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http://dx.doi.org/10.1097/00002030-200305020-00002DOI Listing
May 2003

T-cell repopulation and thymic volume in HIV-1-infected adult patients after highly active antiretroviral therapy.

Blood 2002 May;99(10):3702-6

Department of Internal Medicine, Hospital Universitario Virgen del Rocío, Seville, Spain.

The origin of T cells after highly active antiretroviral therapy (HAART) in patients infected with human immunodeficiency virus 1 (HIV-1) is now under discussion. The possibility of renewed lymphopoiesis in aged thymuses is still controversial. In this work we combine the analysis of naïve T cells, T-cell receptor excision circles (TRECs), and computed tomography scanning of thymic tissue to further assess whether the thymus is involved in immune reconstitution. Fifteen antiretroviral-naïve HIV-1-infected patients were evaluated during 48 weeks of HAART. At baseline, significant correlation was present among age and both thymic volume and TRECs, and between naïve T cells and TRECs. After starting HAART, there was a significant increase at week 12 in naïve CD4(+) and CD8(+) T cells, TRECs, and thymic volume. The initial net increases in naïve T cells and TREC counts were significantly correlated. Changes in thymic volume and TRECs were also indirectly related; splitting the population into 2 groups of high and low baseline TREC levels, only the group with low TREC levels had significant increases in both TRECs and thymic volume. Thus, the increase in thymic volume might be functional, in response to depleted TREC levels. Taken together, our data strongly suggest a thymic role in immune reconstitution, at least in patients with depleted baseline TREC levels. (Blood. 2002;99:3702-3706)
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http://dx.doi.org/10.1182/blood.v99.10.3702DOI Listing
May 2002