Ana Mendez - Academia.edu (original) (raw)
Papers by Ana Mendez
Intraosseous Vascularity of the Distal Radius: Anatomy and Clinical Implications in Distal Radius Fractures
HAND, 2009
This study aimed to describe the intraosseous blood supply of the distal radius and its clinical ... more This study aimed to describe the intraosseous blood supply of the distal radius and its clinical implications in distal radius fractures. Twelve adult wrists from fresh cadavers (six males, six females, 50-90 years of age, mean 68 years) were injected through the brachial artery with latex. Dissections were performed using magnifying loupes and hands were processed using the Spalteholz technique. The distal radius was supplied by three main vascular systems: epiphyseal, metaphyseal, and diaphyseal. The palmar epiphyseal vessels branched from the radial artery, palmar carpal arch, and anterior branch of the anterior interosseous artery. These vessels entered the bone through the radial styloid process at level of the Lister's tubercle but palmar and sigmoid notch. The dorsal contribution to Lister's tubercle is to the dorsal epiphyseal vessels. The intraosseous point of entry to the dorsal epiphyseal vessels was from the fourth and fifth extensor compartment arteries. In the metaphyseal area, we found numerous periosteal and cortical branches originating deep in the pronator quadratus and the anterior interosseous artery. These branches provided the main supply to the distal radius. Vessels perforated the bone and formed an anastomotic network. In the diaphyseal area, only the nutrient vessel provided intraosseous vascularity in the distal radius. Numerous metaphyseal-epiphyseal branches arise within the pronator quadratus and the anterior interosseous artery and course towards the distal radius. These branches may be fundamental to the healing of the distal radius fractures and make nonunion a rare complication.
Antigen selection and presentation to protect against transmissible gastroenteritis coronavirus
Veterinary Microbiology, 1992
The antigenic structure of the S glycoprotein of transmissible gastroenteritis virus (TGEV) and p... more The antigenic structure of the S glycoprotein of transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) has been determined and correlated with the physical structure. Four antigenic sites have been defined (A, B, C, and D). The sites involved in the neutralization of TGEV are: A, D, and B, sites A and D being antigenically dominant for TGEV neutralization in vitro. These two sites have specific properties of interest: site A is highly conserved and is present in coronaviruses of three animal species, and site D can be represented by synthetic peptides. Both sites might be relevant in protection in vivo. PRCV does not have sites B and C, due to a genomic deletion. Complex antigenic sites, i.e., conformation and glycosylation dependent sites, have been represented by simple mimotopes selected from a library expressing recombinant peptides with random sequences, or by anti-idiotypic internal image monoclonal antibodies. An epidemiological tree relating the TGEVs and PRCVs has been proposed. The estimated mutation fixation rate of 7 +/- 2 x 10(-4) substitutions per nucleotide and year indicates that TGEV related coronaviruses show similar variability to other RNA viruses. In order to induce secretory immunity, different segments of the S gene have been expressed using a virulent forms of Salmonella typhimurium and adenovirus. These vectors, with a tropism for Peyer's patches may be ideal candidates in protection against TGEV.
International Review of Education, 1994
Introducing Media Education in Latin America
Educational Media International, 1989
This article shows our experience in training teachers to introduce media education into the educ... more This article shows our experience in training teachers to introduce media education into the educational system, and we give an overview of its purposes and prospects in Latin America. Our model of media education, based upon Golay's (1980) Z scheme, considers three perspectives: demythification, literacy and self‐analysis: all are taxono‐mically ordered from denotation to creativity. We visualize three contexts through
Mouse models to study GCAP functions in intact photoreceptors
Advances in experimental medicine and biology, 2002
In photoreceptor cells cGMP is the second messenger that transduces light into an electrical resp... more In photoreceptor cells cGMP is the second messenger that transduces light into an electrical response. Regulation of cGMP synthesis by Ca2+ is one of the key mechanisms by which Ca2+ exerts negative feedback to the phototransduction cascade in the process of light adaptation. This Ca2+ feedback to retinal guanylyl cyclases (Ret-GCs) is conferred by the guanylate cyclase-activating proteins (GCAPs). Mutations in GCAP1 that disrupt the Ca2+ regulation of Ret-GCs in vitro have been associated with severe human vision disorders. This chapter focuses on recent data obtained from biochemical and electrophysiological studies of GCAP1/GCAP2 knockout mice and other GCAP transgenic mice, addressing: 1. the quantitative aspects of the Ca2+-feedback to Ret-GCs in regulating the light sensitivity and adaptation in intact rods; 2. functional differences between GCAP1 and GCAP2 in intact rod photoreceptors; and 3. whether GCAP mutants with impaired Ca2+ binding lead to retinal disease in vivo by constitutive activation of Ret-GCs and elevation of intracellular cGMP, as predicted from in vitro studies.
Light-dependent translocation of arrestin in the absence of rhodopsin phosphorylation and transducin signaling
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 15, 2003
Visual arrestin plays a crucial role in the termination of the light response in vertebrate photo... more Visual arrestin plays a crucial role in the termination of the light response in vertebrate photoreceptors by binding selectively to light-activated, phosphorylated rhodopsin. Arrestin localizes predominantly to the inner segments and perinuclear region of dark-adapted rod photoreceptors, whereas light induces redistribution of arrestin to the rod outer segments. The mechanism by which arrestin redistributes in response to light is not known, but it is thought to be associated with the ability of arrestin to bind photolyzed, phosphorylated rhodopsin in the outer segment. In this study, we show that light-driven translocation of arrestin is unaffected in two different mouse models in which rhodopsin phosphorylation is lacking. We further show that arrestin movement is initiated by rhodopsin but does not require transducin signaling. These results exclude passive diffusion and point toward active transport as the mechanism for light-dependent arrestin movement in rod photoreceptor cells.
Current biology : CB, Jan 28, 2009
G protein-coupled receptors (GPCRs) are the largest family of signaling proteins expressed in eve... more G protein-coupled receptors (GPCRs) are the largest family of signaling proteins expressed in every cell in the body and targeted by the majority of clinically used drugs . GPCR signaling, including rhodopsin-drive phototransduction, is terminated by receptor phosphorylation followed by arrestin binding . Genetic defects in receptor phosphorylation and excessive signaling by overactive GPCR mutants result in a wide variety of diseases, from retinal degeneration to cancer . Here we tested whether arrestin1 mutants with enhanced ability to bind active unphosphorylated rhodopsin [7-10] can suppress uncontrolled signaling, bypassing receptor phosphorylation by rhodopsin kinase (RK) and replacing this two-step mechanism with a single step deactivation in rod photoreceptors. We show that in this precisely timed signaling system with single photon sensitivity , an "enhanced" arrestin1 mutant partially compensates for defects in rhodopsin phosphorylation, promoting photoreceptor survival, improving functional performance, and facilitating photoresponse recovery. These proof-of-principle experiments demonstrate the feasibility of functional compensation in vivo for the first time, which is a promising approach for correcting genetic defects associated with gain-of-function mutations. Successful modification of protein-protein interactions by appropriate mutations paves the way to targeted redesign of signaling pathways to achieve desired functional outcomes.
Unusual case of new-onset heart failure due to cor triatriatum sinister
European journal of heart failure, 2013
We report the case of a 30-year old man who came to the emergency department of our hospital with... more We report the case of a 30-year old man who came to the emergency department of our hospital with acute left heart failure, and was diagnosed with a rare congenital anomaly (cor triatriatrum sinister), which can mimic a severe mitral stenosis. Cor triatriatum sinister is a rare anomaly (0.1% of all cases of congenital heart disease) that is seldom diagnosed in adult patients. The hallmark of this congenital defect is the presence of a fibromuscular membrane that divides the left atrium (LA) into two chambers: a postero-superior chamber into which the pulmonary veins drain and an infero-anterior chamber (true LA) containing the mitral valve and atrial appendage. Both chambers communicate through a membrane in which one or more drain holes can be found. When the hole is significantly obstructive, it results in increased venous and arterial pressures. Even though the definitive treatment of cor triatriatum is the surgical excision of the membrane, we present a balloon dilatation case with a good response to percutaneous therapy, both initially and in the ensuing months.
PLoS genetics, 2014
The neuronal calcium sensor proteins GCAPs (guanylate cyclase activating proteins) switch between... more The neuronal calcium sensor proteins GCAPs (guanylate cyclase activating proteins) switch between Ca 2+ -free and Ca 2+bound conformational states and confer calcium sensitivity to guanylate cyclase at retinal photoreceptor cells. They play a fundamental role in light adaptation by coupling the rate of cGMP synthesis to the intracellular concentration of calcium. Mutations in GCAPs lead to blindness. The importance of functional EF-hands in GCAP1 for photoreceptor cell integrity has been well established. Mutations in GCAP1 that diminish its Ca 2+ binding affinity lead to cell damage by causing unabated cGMP synthesis and accumulation of toxic levels of free cGMP and Ca 2+ . We here investigate the relevance of GCAP2 functional EF-hands for photoreceptor cell integrity. By characterizing transgenic mice expressing a mutant form of GCAP2 with all EF-hands inactivated (EF 2 GCAP2), we show that GCAP2 locked in its Ca 2+ -free conformation leads to a rapid retinal degeneration that is not due to unabated cGMP synthesis. We unveil that when locked in its Ca 2+ -free conformation in vivo, GCAP2 is phosphorylated at Ser201 and results in phospho-dependent binding to the chaperone 14-3-3 and retention at the inner segment and proximal cell compartments. Accumulation of phosphorylated EF 2 GCAP2 at the inner segment results in severe toxicity. We show that in wildtype mice under physiological conditions, 50% of GCAP2 is phosphorylated correlating with the 50% of the protein being retained at the inner segment. Raising mice under constant light exposure, however, drastically increases the retention of GCAP2 in its Ca 2+ -free form at the inner segment. This study identifies a new mechanism governing GCAP2 subcellular distribution in vivo, closely related to disease. It also identifies a pathway by which a sustained reduction in intracellular free Ca 2+ could result in photoreceptor damage, relevant for light damage and for those genetic disorders resulting in ''equivalent-light'' scenarios.
Dynamics of Cyclic GMP Synthesis in Retinal Rods
Neuron, 2002
In retinal rods, Ca(2+) exerts negative feedback control on cGMP synthesis by guanylate cyclase (... more In retinal rods, Ca(2+) exerts negative feedback control on cGMP synthesis by guanylate cyclase (GC). This feedback loop was disrupted in mouse rods lacking guanylate cyclase activating proteins GCAP1 and GCAP2 (GCAPs(-/-)). Comparison of the behavior of wild-type and GCAPs(-/-) rods allowed us to investigate the role of the feedback loop in normal rod function. We have found that regulation of GC is apparently the only Ca(2+) feedback loop operating during the single photon response. Analysis of the rods' light responses and cellular dark noise suggests that GC normally responds to light-driven changes in [Ca(2+)] rapidly and highly cooperatively. Rapid feedback to GC speeds the rod's temporal responsiveness and improves its signal-to-noise ratio by minimizing fluctuations in cGMP.
Vision Research, 2002
The role of the carboxyl-terminal domain in rhodopsin transport was investigated using transgenic... more The role of the carboxyl-terminal domain in rhodopsin transport was investigated using transgenic mice expressing a rhodopsin truncation mutant lacking the terminal 15 amino acids (S334ter). It was previously shown that S334ter translocates to the outer segment in the presence of endogenous rhodopsin. We now show that in the absence of endogenous rhodopsin S334ter mis-localizes to the plasma membrane and fails to reconstitute outer segment structures. Surprisingly, this mis-localization does not affect photoreceptor cell survival. These results provide further evidence on the important role of the COOH-terminal domain in rhodopsin trafficking and demonstrate an absolute requirement of this domain for correct vectorial transport of rhodopsin in rod photoreceptors. Ó
[11] Functional study of rhodopsin phosphorylation in vivo
Methods in Enzymology, 2000
ABSTRACT Phosphorylation of rhodopsin is a key reaction in the termination of the light response.... more ABSTRACT Phosphorylation of rhodopsin is a key reaction in the termination of the light response. It is the first step in rhodopsin inactivation, beginning 100 msec after the light stimulus. A subsequent step, the binding of arrestin to phosphorylated rhodopsin, is necessary to complete inactivation. Extensive work has been done to address basic aspects of rhodopsin Phosphorylation. Its importance in rhodopsin shutoff was first identified by in vitro reconstitution studies. The sites of phosphorylation on rhodopsin were localized at several serine and threonine residues at the cytoplasmic carboxyl terminus of rhodopsin, and the most favored sites in vitro were reported as Ser-338 and Ser-343 by three independent studies. The carboxyl terminus of rhodopsin was isolated from photoreceptor disk membranes and analyzed by chromatographic separation and mass spectrometry. This chapter describes how to generate transgenic mice expressing rhodopsin mutants at the phosphorylation sites and how to characterize the lines in terms of transgene expression and retinal morphology. It also describes the criteria used in the selection of mice for electrophysiological recordings so that light responses elicited by mutant rhodopsins can be unequivocally assigned.
Prognostic value of increased carbohydrate antigen in patients with heart failure
World journal of cardiology, Jan 26, 2014
To study the prognostic value of carbohydrate antigen 125 (CA125) and whether it adds prognostic ... more To study the prognostic value of carbohydrate antigen 125 (CA125) and whether it adds prognostic information to N-terminal pro-brain natriuretic peptide (NT-proBNP) in stable heart failure (HF) patients. The predictive value of CA125 was retrospectively assessed in 156 patients with stable HF remitted to the outpatient HF unit for monitoring from 2009 to 2011. Patients were included in the study if they had a previous documented episode of HF and received HF treatment. CA125 and NT-proBNP concentrations were measured. The independent association between NT-proBNP or CA125 and mortality was assessed with Cox regression analysis, and their combined predictive ability was tested by the integrated discrimination improvement (IDI) index. The mean age of the 156 patients was 72 ± 12 years. During follow-up (17 ± 8 mo), 27 patients died, 1 received an urgent heart transplantation and 106 required hospitalization for HF. Higher CA125 values were correlated with outcomes: 58 ± 85 KU/L if hospitalized vs 34 ± 61 KU/L if not (P < 0.05), and 94 ± 121 KU/L in those who died or needed urgent heart transplantation vs 45 ± 78 KU/L in survivors (P < 0.01). After adjusting for propensity scores, the highest risk was observed when both biomarkers were elevated vs not elevated (HR = 8.95, 95%CI: 3.11-25.73; P < 0.001) and intermediate when only NT-proBNP was elevated vs not elevated (HR = 4.15, 95%CI: 1.41-12.24; P < 0.01). Moreover, when CA125 was added to the clinical model with NT-proBNP, a 4% (P < 0.05) improvement in the IDI was found. CA125 > 60 KU/L identified patients in stable HF with poor survival. Circulating CA125 level adds prognostic value to NT-proBNP level in predicting HF outcomes.
Revista española de cardiología (English ed.), 2014
Predictive value of high-sensitive troponin T to rule out acute rejection after heart transplantation
Revista española de cardiología (English ed.), 2014
Revista Española de Cardiología (English Edition), 2014
Intraosseous Vascularity of the Distal Radius: Anatomy and Clinical Implications in Distal Radius Fractures
HAND, 2009
This study aimed to describe the intraosseous blood supply of the distal radius and its clinical ... more This study aimed to describe the intraosseous blood supply of the distal radius and its clinical implications in distal radius fractures. Twelve adult wrists from fresh cadavers (six males, six females, 50-90 years of age, mean 68 years) were injected through the brachial artery with latex. Dissections were performed using magnifying loupes and hands were processed using the Spalteholz technique. The distal radius was supplied by three main vascular systems: epiphyseal, metaphyseal, and diaphyseal. The palmar epiphyseal vessels branched from the radial artery, palmar carpal arch, and anterior branch of the anterior interosseous artery. These vessels entered the bone through the radial styloid process at level of the Lister's tubercle but palmar and sigmoid notch. The dorsal contribution to Lister's tubercle is to the dorsal epiphyseal vessels. The intraosseous point of entry to the dorsal epiphyseal vessels was from the fourth and fifth extensor compartment arteries. In the metaphyseal area, we found numerous periosteal and cortical branches originating deep in the pronator quadratus and the anterior interosseous artery. These branches provided the main supply to the distal radius. Vessels perforated the bone and formed an anastomotic network. In the diaphyseal area, only the nutrient vessel provided intraosseous vascularity in the distal radius. Numerous metaphyseal-epiphyseal branches arise within the pronator quadratus and the anterior interosseous artery and course towards the distal radius. These branches may be fundamental to the healing of the distal radius fractures and make nonunion a rare complication.
Antigen selection and presentation to protect against transmissible gastroenteritis coronavirus
Veterinary Microbiology, 1992
The antigenic structure of the S glycoprotein of transmissible gastroenteritis virus (TGEV) and p... more The antigenic structure of the S glycoprotein of transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) has been determined and correlated with the physical structure. Four antigenic sites have been defined (A, B, C, and D). The sites involved in the neutralization of TGEV are: A, D, and B, sites A and D being antigenically dominant for TGEV neutralization in vitro. These two sites have specific properties of interest: site A is highly conserved and is present in coronaviruses of three animal species, and site D can be represented by synthetic peptides. Both sites might be relevant in protection in vivo. PRCV does not have sites B and C, due to a genomic deletion. Complex antigenic sites, i.e., conformation and glycosylation dependent sites, have been represented by simple mimotopes selected from a library expressing recombinant peptides with random sequences, or by anti-idiotypic internal image monoclonal antibodies. An epidemiological tree relating the TGEVs and PRCVs has been proposed. The estimated mutation fixation rate of 7 +/- 2 x 10(-4) substitutions per nucleotide and year indicates that TGEV related coronaviruses show similar variability to other RNA viruses. In order to induce secretory immunity, different segments of the S gene have been expressed using a virulent forms of Salmonella typhimurium and adenovirus. These vectors, with a tropism for Peyer's patches may be ideal candidates in protection against TGEV.
International Review of Education, 1994
Introducing Media Education in Latin America
Educational Media International, 1989
This article shows our experience in training teachers to introduce media education into the educ... more This article shows our experience in training teachers to introduce media education into the educational system, and we give an overview of its purposes and prospects in Latin America. Our model of media education, based upon Golay's (1980) Z scheme, considers three perspectives: demythification, literacy and self‐analysis: all are taxono‐mically ordered from denotation to creativity. We visualize three contexts through
Mouse models to study GCAP functions in intact photoreceptors
Advances in experimental medicine and biology, 2002
In photoreceptor cells cGMP is the second messenger that transduces light into an electrical resp... more In photoreceptor cells cGMP is the second messenger that transduces light into an electrical response. Regulation of cGMP synthesis by Ca2+ is one of the key mechanisms by which Ca2+ exerts negative feedback to the phototransduction cascade in the process of light adaptation. This Ca2+ feedback to retinal guanylyl cyclases (Ret-GCs) is conferred by the guanylate cyclase-activating proteins (GCAPs). Mutations in GCAP1 that disrupt the Ca2+ regulation of Ret-GCs in vitro have been associated with severe human vision disorders. This chapter focuses on recent data obtained from biochemical and electrophysiological studies of GCAP1/GCAP2 knockout mice and other GCAP transgenic mice, addressing: 1. the quantitative aspects of the Ca2+-feedback to Ret-GCs in regulating the light sensitivity and adaptation in intact rods; 2. functional differences between GCAP1 and GCAP2 in intact rod photoreceptors; and 3. whether GCAP mutants with impaired Ca2+ binding lead to retinal disease in vivo by constitutive activation of Ret-GCs and elevation of intracellular cGMP, as predicted from in vitro studies.
Light-dependent translocation of arrestin in the absence of rhodopsin phosphorylation and transducin signaling
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 15, 2003
Visual arrestin plays a crucial role in the termination of the light response in vertebrate photo... more Visual arrestin plays a crucial role in the termination of the light response in vertebrate photoreceptors by binding selectively to light-activated, phosphorylated rhodopsin. Arrestin localizes predominantly to the inner segments and perinuclear region of dark-adapted rod photoreceptors, whereas light induces redistribution of arrestin to the rod outer segments. The mechanism by which arrestin redistributes in response to light is not known, but it is thought to be associated with the ability of arrestin to bind photolyzed, phosphorylated rhodopsin in the outer segment. In this study, we show that light-driven translocation of arrestin is unaffected in two different mouse models in which rhodopsin phosphorylation is lacking. We further show that arrestin movement is initiated by rhodopsin but does not require transducin signaling. These results exclude passive diffusion and point toward active transport as the mechanism for light-dependent arrestin movement in rod photoreceptor cells.
Current biology : CB, Jan 28, 2009
G protein-coupled receptors (GPCRs) are the largest family of signaling proteins expressed in eve... more G protein-coupled receptors (GPCRs) are the largest family of signaling proteins expressed in every cell in the body and targeted by the majority of clinically used drugs . GPCR signaling, including rhodopsin-drive phototransduction, is terminated by receptor phosphorylation followed by arrestin binding . Genetic defects in receptor phosphorylation and excessive signaling by overactive GPCR mutants result in a wide variety of diseases, from retinal degeneration to cancer . Here we tested whether arrestin1 mutants with enhanced ability to bind active unphosphorylated rhodopsin [7-10] can suppress uncontrolled signaling, bypassing receptor phosphorylation by rhodopsin kinase (RK) and replacing this two-step mechanism with a single step deactivation in rod photoreceptors. We show that in this precisely timed signaling system with single photon sensitivity , an "enhanced" arrestin1 mutant partially compensates for defects in rhodopsin phosphorylation, promoting photoreceptor survival, improving functional performance, and facilitating photoresponse recovery. These proof-of-principle experiments demonstrate the feasibility of functional compensation in vivo for the first time, which is a promising approach for correcting genetic defects associated with gain-of-function mutations. Successful modification of protein-protein interactions by appropriate mutations paves the way to targeted redesign of signaling pathways to achieve desired functional outcomes.
Unusual case of new-onset heart failure due to cor triatriatum sinister
European journal of heart failure, 2013
We report the case of a 30-year old man who came to the emergency department of our hospital with... more We report the case of a 30-year old man who came to the emergency department of our hospital with acute left heart failure, and was diagnosed with a rare congenital anomaly (cor triatriatrum sinister), which can mimic a severe mitral stenosis. Cor triatriatum sinister is a rare anomaly (0.1% of all cases of congenital heart disease) that is seldom diagnosed in adult patients. The hallmark of this congenital defect is the presence of a fibromuscular membrane that divides the left atrium (LA) into two chambers: a postero-superior chamber into which the pulmonary veins drain and an infero-anterior chamber (true LA) containing the mitral valve and atrial appendage. Both chambers communicate through a membrane in which one or more drain holes can be found. When the hole is significantly obstructive, it results in increased venous and arterial pressures. Even though the definitive treatment of cor triatriatum is the surgical excision of the membrane, we present a balloon dilatation case with a good response to percutaneous therapy, both initially and in the ensuing months.
PLoS genetics, 2014
The neuronal calcium sensor proteins GCAPs (guanylate cyclase activating proteins) switch between... more The neuronal calcium sensor proteins GCAPs (guanylate cyclase activating proteins) switch between Ca 2+ -free and Ca 2+bound conformational states and confer calcium sensitivity to guanylate cyclase at retinal photoreceptor cells. They play a fundamental role in light adaptation by coupling the rate of cGMP synthesis to the intracellular concentration of calcium. Mutations in GCAPs lead to blindness. The importance of functional EF-hands in GCAP1 for photoreceptor cell integrity has been well established. Mutations in GCAP1 that diminish its Ca 2+ binding affinity lead to cell damage by causing unabated cGMP synthesis and accumulation of toxic levels of free cGMP and Ca 2+ . We here investigate the relevance of GCAP2 functional EF-hands for photoreceptor cell integrity. By characterizing transgenic mice expressing a mutant form of GCAP2 with all EF-hands inactivated (EF 2 GCAP2), we show that GCAP2 locked in its Ca 2+ -free conformation leads to a rapid retinal degeneration that is not due to unabated cGMP synthesis. We unveil that when locked in its Ca 2+ -free conformation in vivo, GCAP2 is phosphorylated at Ser201 and results in phospho-dependent binding to the chaperone 14-3-3 and retention at the inner segment and proximal cell compartments. Accumulation of phosphorylated EF 2 GCAP2 at the inner segment results in severe toxicity. We show that in wildtype mice under physiological conditions, 50% of GCAP2 is phosphorylated correlating with the 50% of the protein being retained at the inner segment. Raising mice under constant light exposure, however, drastically increases the retention of GCAP2 in its Ca 2+ -free form at the inner segment. This study identifies a new mechanism governing GCAP2 subcellular distribution in vivo, closely related to disease. It also identifies a pathway by which a sustained reduction in intracellular free Ca 2+ could result in photoreceptor damage, relevant for light damage and for those genetic disorders resulting in ''equivalent-light'' scenarios.
Dynamics of Cyclic GMP Synthesis in Retinal Rods
Neuron, 2002
In retinal rods, Ca(2+) exerts negative feedback control on cGMP synthesis by guanylate cyclase (... more In retinal rods, Ca(2+) exerts negative feedback control on cGMP synthesis by guanylate cyclase (GC). This feedback loop was disrupted in mouse rods lacking guanylate cyclase activating proteins GCAP1 and GCAP2 (GCAPs(-/-)). Comparison of the behavior of wild-type and GCAPs(-/-) rods allowed us to investigate the role of the feedback loop in normal rod function. We have found that regulation of GC is apparently the only Ca(2+) feedback loop operating during the single photon response. Analysis of the rods' light responses and cellular dark noise suggests that GC normally responds to light-driven changes in [Ca(2+)] rapidly and highly cooperatively. Rapid feedback to GC speeds the rod's temporal responsiveness and improves its signal-to-noise ratio by minimizing fluctuations in cGMP.
Vision Research, 2002
The role of the carboxyl-terminal domain in rhodopsin transport was investigated using transgenic... more The role of the carboxyl-terminal domain in rhodopsin transport was investigated using transgenic mice expressing a rhodopsin truncation mutant lacking the terminal 15 amino acids (S334ter). It was previously shown that S334ter translocates to the outer segment in the presence of endogenous rhodopsin. We now show that in the absence of endogenous rhodopsin S334ter mis-localizes to the plasma membrane and fails to reconstitute outer segment structures. Surprisingly, this mis-localization does not affect photoreceptor cell survival. These results provide further evidence on the important role of the COOH-terminal domain in rhodopsin trafficking and demonstrate an absolute requirement of this domain for correct vectorial transport of rhodopsin in rod photoreceptors. Ó
[11] Functional study of rhodopsin phosphorylation in vivo
Methods in Enzymology, 2000
ABSTRACT Phosphorylation of rhodopsin is a key reaction in the termination of the light response.... more ABSTRACT Phosphorylation of rhodopsin is a key reaction in the termination of the light response. It is the first step in rhodopsin inactivation, beginning 100 msec after the light stimulus. A subsequent step, the binding of arrestin to phosphorylated rhodopsin, is necessary to complete inactivation. Extensive work has been done to address basic aspects of rhodopsin Phosphorylation. Its importance in rhodopsin shutoff was first identified by in vitro reconstitution studies. The sites of phosphorylation on rhodopsin were localized at several serine and threonine residues at the cytoplasmic carboxyl terminus of rhodopsin, and the most favored sites in vitro were reported as Ser-338 and Ser-343 by three independent studies. The carboxyl terminus of rhodopsin was isolated from photoreceptor disk membranes and analyzed by chromatographic separation and mass spectrometry. This chapter describes how to generate transgenic mice expressing rhodopsin mutants at the phosphorylation sites and how to characterize the lines in terms of transgene expression and retinal morphology. It also describes the criteria used in the selection of mice for electrophysiological recordings so that light responses elicited by mutant rhodopsins can be unequivocally assigned.
Prognostic value of increased carbohydrate antigen in patients with heart failure
World journal of cardiology, Jan 26, 2014
To study the prognostic value of carbohydrate antigen 125 (CA125) and whether it adds prognostic ... more To study the prognostic value of carbohydrate antigen 125 (CA125) and whether it adds prognostic information to N-terminal pro-brain natriuretic peptide (NT-proBNP) in stable heart failure (HF) patients. The predictive value of CA125 was retrospectively assessed in 156 patients with stable HF remitted to the outpatient HF unit for monitoring from 2009 to 2011. Patients were included in the study if they had a previous documented episode of HF and received HF treatment. CA125 and NT-proBNP concentrations were measured. The independent association between NT-proBNP or CA125 and mortality was assessed with Cox regression analysis, and their combined predictive ability was tested by the integrated discrimination improvement (IDI) index. The mean age of the 156 patients was 72 ± 12 years. During follow-up (17 ± 8 mo), 27 patients died, 1 received an urgent heart transplantation and 106 required hospitalization for HF. Higher CA125 values were correlated with outcomes: 58 ± 85 KU/L if hospitalized vs 34 ± 61 KU/L if not (P < 0.05), and 94 ± 121 KU/L in those who died or needed urgent heart transplantation vs 45 ± 78 KU/L in survivors (P < 0.01). After adjusting for propensity scores, the highest risk was observed when both biomarkers were elevated vs not elevated (HR = 8.95, 95%CI: 3.11-25.73; P < 0.001) and intermediate when only NT-proBNP was elevated vs not elevated (HR = 4.15, 95%CI: 1.41-12.24; P < 0.01). Moreover, when CA125 was added to the clinical model with NT-proBNP, a 4% (P < 0.05) improvement in the IDI was found. CA125 > 60 KU/L identified patients in stable HF with poor survival. Circulating CA125 level adds prognostic value to NT-proBNP level in predicting HF outcomes.
Revista española de cardiología (English ed.), 2014
Predictive value of high-sensitive troponin T to rule out acute rejection after heart transplantation
Revista española de cardiología (English ed.), 2014
Revista Española de Cardiología (English Edition), 2014