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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 312: 124050, 2024 May 05.
Article in English | MEDLINE | ID: mdl-38402702

ABSTRACT

Emerging evidence suggests that elevated levels of folic acid in the bloodstream may confer protection against Wuhan-SARS-CoV-2 infection and mitigate its associated symptoms. Notably, two comprehensive studies of COVID-19 patients in Israel and UK uncovered a remarkable trend, wherein individuals with heightened folic acid levels exhibited only mild symptoms and necessitated no ventilatory support. In parallel, research has underscored the potential connection between decreased folic acid levels and the severity of Covid-19 among hospitalized patients. Yet, the underlying mechanisms governing this intriguing inhibition remain elusive. In a quest to elucidate these mechanisms, we conducted a molecular dynamics simulation approach followed by a Raman spectroscopy study to delve into the intricate interplay between the folic acid metabolite, 7,8-dihydrofolate (DHF), and the angiotensin-converting enzyme ACE2 receptor, coupled with its interaction with the receptor-binding domain (RBD) of the Wuhan strain of SARS-CoV-2. Through a meticulous exploration, we scrutinized the transformation of the ACE2 + RBD complex, allowing these reactants to form bonds. This was juxtaposed with a similar investigation where ACE2 was initially permitted to react with DHF, followed by the exposure of the ACE2 + DHF complex to RBD. We find that DHF, when bonded to ACE2, functions as a physical barrier, effectively inhibiting the binding of the Wuhan strain RBD. This physicochemical process offers a cogent explanation for the observed inhibition of host cell infection in subjects receiving supplementary folic acid doses, as epidemiologically substantiated in multiple studies. This study not only sheds light on a potential avenue for mitigating SARS-CoV-2 infection but also underscores the crucial role of folic acid metabolites in host-virus interactions. This research paves the way for novel therapeutic strategies in the battle against COVID-19 and reinforces the significance of investigating the molecular mechanisms underlying the protective effects of folic acid in the context of viral infections.


Subject(s)
COVID-19 , Folic Acid , SARS-CoV-2 , Humans , Angiotensin-Converting Enzyme 2 , Folic Acid/analogs & derivatives , Folic Acid/metabolism , Folic Acid/pharmacology , Molecular Dynamics Simulation , Protein Binding , Spectrum Analysis, Raman
2.
Neurosurgery ; 2023 Dec 05.
Article in English | MEDLINE | ID: mdl-38051042

ABSTRACT

BACKGROUND AND OBJECTIVES: Our Phase-I parallel-cohort study suggested that managing severe traumatic brain injury (sTBI) in the absence of intracranial pressure (ICP) monitoring using an ad hoc Imaging and Clinical Examination (ICE) treatment protocol was associated with superior outcome vs nonprotocolized management but could not differentiate the influence of protocolization from that of the specific protocol. Phase II investigates whether adopting the Consensus REVised Imaging and Clinical Examination (CREVICE) protocol improved outcome directly or indirectly via protocolization. METHODS: We performed a Phase-II sequential parallel-cohort study examining adoption of the CREVICE protocol from no protocol vs a previous protocol in patients with sTBI older than 13 years presenting ≤24 hours after injury. Primary outcome was prespecified 6-month recovery. The study was done mostly at public South American centers managing sTBI without ICP monitoring. Fourteen Phase-I nonprotocol centers and 5 Phase-I protocol centers adopted CREVICE. Data were analyzed using generalized estimating equation regression adjusting for demographic imbalances. RESULTS: A total of 501 patients (86% male, mean age 35.4 years) enrolled; 81% had 6 months of follow-up. Adopting CREVICE from no protocol was associated with significantly superior results for overall 6-month extended Glasgow Outcome Score (GOSE) (protocol effect = 0.53 [0.11, 0.95], P = .013), mortality (36% vs 21%, HR = 0.59 [0.46, 0.76], P < .001), and orientation (Galveston Orientation and Amnesia Test discharge protocol effect = 10.9 [6.0, 15.8], P < .001, 6-month protocol effect = 11.4 [4.1, 18.6], P < .005). Adopting CREVICE from ICE was associated with significant benefits to GOSE (protocol effect = 0.51 [0.04, 0.98], P = .033), 6-month mortality (25% vs 18%, HR = 0.55 [0.39, 0.77], P < .001), and orientation (Galveston Orientation and Amnesia Test 6-month protocol effect = 9.2 [3.6, 14.7], P = .004). Comparing both groups using CREVICE, those who had used ICE previously had significantly better GOSE (protocol effect = 1.15 [0.09, 2.20], P = .033). CONCLUSION: Centers managing adult sTBI without ICP monitoring should strongly consider protocolization through adopting/adapting the CREVICE protocol. Protocolization is indirectly supported at sTBI centers regardless of resource availability.

3.
Neurosurgery ; 92(3): 472-480, 2023 03 01.
Article in English | MEDLINE | ID: mdl-36790211

ABSTRACT

BACKGROUND: Most patients with severe traumatic brain injury (sTBI) in low- or-middle-income countries and surprisingly many in high-income countries are managed without intracranial pressure (ICP) monitoring. The impact of the first published protocol (Imaging and Clinical Examination [ICE] protocol) is untested against nonprotocol management. OBJECTIVE: To determine whether patients treated in intensive care units (ICUs) using the ICE protocol have lower mortality and better neurobehavioral functioning than those treated in ICUs using no protocol. METHODS: This study involved nineteen mostly public South American hospitals. This is a prospective cohort study, enrolling patients older than 13 years with sTBI presenting within 24 h of injury (January 2014-July 2015) with 6-mo postinjury follow-up. Five hospitals treated all sTBI cases using the ICE protocol; 14 used no protocol. Primary outcome was prespecified composite of mortality, orientation, functional outcome, and neuropsychological measures. RESULTS: A total of 414 patients (89% male, mean age 34.8 years) enrolled; 81% had 6 months of follow-up. All participants included in composite outcome analysis: average percentile (SD) = 46.8 (24.0) nonprotocol, 56.9 (24.5) protocol. Generalized estimating equation (GEE) used to account for center effects (confounder-adjusted difference [95% CI] = 12.2 [4.6, 19.8], P = .002). Kaplan-Meier 6-month mortality (95% CI) = 36% (30%, 43%) nonprotocol, 25% (19%, 31%) protocol (GEE and confounder-adjusted hazard ratio [95% CI] = .69 [.43, 1.10], P = .118). Six-month Extended Glasgow Outcome Scale for 332 participants: average Extended Glasgow Outcome Scale score (SD) = 3.6 (2.6) nonprotocol, 4.7 (2.8) protocol (GEE and confounder-adjusted and lost to follow-up-adjusted difference [95% CI] = 1.36 [.55, 2.17], P = .001). CONCLUSION: ICUs managing patients with sTBI using the ICE protocol had better functional outcome than those not using a protocol. ICUs treating patients with sTBI without ICP monitoring should consider protocolization. The ICE protocol, tested here and previously, is 1 option.


Subject(s)
Brain Injuries, Traumatic , Brain Injuries , Humans , Male , Adult , Female , Intracranial Pressure , Prospective Studies , Brain Injuries, Traumatic/diagnostic imaging , Brain Injuries, Traumatic/therapy , Monitoring, Physiologic/methods
4.
J Neurotrauma ; 37(11): 1291-1299, 2020 06 01.
Article in English | MEDLINE | ID: mdl-32013721

ABSTRACT

Globally, intracranial pressure (ICP) monitoring use in severe traumatic brain injury (sTBI) is inconsistent and susceptible to resource limitations and clinical philosophies. For situations without monitoring, there is no published comprehensive management algorithm specific to identifying and treating suspected intracranial hypertension (SICH) outside of the one ad hoc Imaging and Clinical Examination (ICE) protocol in the Benchmark Evidence from South American Trials: Treatment of Intracranial Pressure (BEST:TRIP) trial. As part of an ongoing National Institutes of Health (NIH)-supported project, a consensus conference involving 43 experienced Latin American Intensivists and Neurosurgeons who routinely care for sTBI patients without ICP monitoring, refined, revised, and augmented the original BEST:TRIP algorithm. Based on BEST:TRIP trial data and pre-meeting polling, 11 issues were targeted for development. We used Delphi-based methodology to codify individual statements and the final algorithm, using a group agreement threshold of 80%. The resulting CREVICE (Consensus REVised ICE) algorithm defines SICH and addresses both general management and specific treatment. SICH treatment modalities are organized into tiers to guide treatment escalation and tapering. Treatment schedules were developed to facilitate targeted management of disease severity. A decision-support model, based on the group's combined practices, is provided to guide this process. This algorithm provides the first comprehensive management algorithm for treating sTBI patients when ICP monitoring is not available. It is intended to provide a framework to guide clinical care and direct future research toward sTBI management. Because of the dearth of relevant literature, it is explicitly consensus based, and is provided solely as a resource (a "consensus-based curbside consult") to assist in treating sTBI in general intensive care units in resource-limited environments.


Subject(s)
Brain Injuries, Traumatic/diagnostic imaging , Clinical Protocols/standards , Consensus , Intracranial Pressure/physiology , Monitoring, Physiologic/standards , Severity of Illness Index , Brain Injuries, Traumatic/physiopathology , Delphi Technique , Humans , Intracranial Hypertension/diagnostic imaging , Intracranial Hypertension/physiopathology , Neurosurgeons/standards , Treatment Outcome
5.
World Neurosurg ; 111: e82-e90, 2018 Mar.
Article in English | MEDLINE | ID: mdl-29229352

ABSTRACT

BACKGROUND: Traumatic brain injury (TBI) disproportionately affects lower- and middle-income countries (LMIC). The factors influencing outcomes in LMIC have not been examined as rigorously as in higher-income countries. METHODS: This study was conducted to examine clinical and demographic factors influencing TBI outcomes in Latin American LMIC. Data were prospectively collected during a randomized trial of intracranial pressure monitoring in severe TBI and a companion observational study. Participants were aged ≥13 years and admitted to study hospitals with Glasgow Coma Scale score ≤8. The primary outcome was Glasgow Outcome Scale, Extended (GOS-E) score at 6 months. Predictors were analyzed using a multivariable proportional odds model created by forward stepwise selection. RESULTS: A total of 550 patients were identified. Six-month outcomes were available for 88%, of whom 37% had died and 44% had achieved a GOS-E score of 5-8. In multivariable proportional odds modeling, higher Glasgow Coma Scale motor score (odds ratio [OR], 1.41 per point; 95% confidence interval [CI], 1.23-1.61) and epidural hematoma (OR, 1.83; 95% CI, 1.17-2.86) were significant predictors of higher GOS-E score, whereas advanced age (OR, 0.65 per 10 years; 95% CI, 0.57-0.73) and cisternal effacement (P < 0.001) were associated with lower GOS-E score. Study site (P < 0.001) and race (P = 0.004) significantly predicted outcome, outweighing clinical variables such as hypotension and pupillary examination. CONCLUSIONS: Mortality from severe TBI is high in Latin American LMIC, although the rate of favorable recovery is similar to that of high-income countries. Demographic factors such as race and study site played an outsized role in predicting outcome; further research is required to understand these associations.


Subject(s)
Brain Injuries, Traumatic/therapy , Adult , Brain Injuries, Traumatic/mortality , Brain Injuries, Traumatic/physiopathology , Female , Glasgow Coma Scale , Glasgow Outcome Scale , Humans , Intracranial Pressure , Latin America/epidemiology , Male , Multivariate Analysis , Odds Ratio , Prospective Studies , South America/epidemiology , Treatment Outcome , Young Adult
6.
J Neurotrauma ; 35(1): 54-63, 2018 01 01.
Article in English | MEDLINE | ID: mdl-28726590

ABSTRACT

The imaging and clinical examination (ICE) algorithm used in the Benchmark Evidence from South American Trials: Treatment of Intracranial Pressure (BEST TRIP) randomized controlled trial is the only prospectively investigated clinical protocol for traumatic brain injury management without intracranial pressure (ICP) monitoring. As the default literature standard, it warrants careful evaluation. We present the ICE protocol in detail and analyze the demographics, outcome, treatment intensity, frequency of intervention usage, and related adverse events in the ICE-protocol cohort. The 167 ICE protocol patients were young (median 29 years) with a median Glasgow Coma Scale motor score of 4 but with anisocoria or abnormal pupillary reactivity in 40%. This protocol produced outcomes not significantly different from those randomized to the monitor-based protocol (favorable 6-month extended Glasgow Outcome Score in 39%; 41% mortality rate). Agents commonly employed to treat suspected intracranial hypertension included low-/moderate-dose hypertonic saline (72%) and mannitol (57%), mild hyperventilation (adjusted partial pressure of carbon dioxide 30-35 mm Hg in 73%), and pressors to maintain cerebral perfusion (62%). High-dose hyperosmotics or barbiturates were uncommonly used. Adverse event incidence was low and comparable to the BEST TRIP monitored group. Although this protocol should produce similar/acceptable results under circumstances comparable to those in the trial, influences such as longer pre-hospital times and non-specialist transport personnel, plus an intensive care unit model of aggressive physician-intensive care by small groups of neurotrauma-focused intensivists, which differs from most high-resource models, support caution in expecting the same results in dissimilar settings. Finally, this protocol's ICP-titration approach to suspected intracranial hypertension (vs. crisis management for monitored ICP) warrants further study.


Subject(s)
Brain Injuries, Traumatic/diagnosis , Brain Injuries, Traumatic/therapy , Clinical Protocols , Adult , Algorithms , Female , Humans , Intracranial Pressure , Male , Middle Aged , Neurologic Examination , Tomography, X-Ray Computed , Young Adult
7.
Bol. méd. Hosp. Infant. Méx ; 74(5): 364-369, sep.-oct. 2017. graf
Article in Spanish | LILACS | ID: biblio-951273

ABSTRACT

Resumen: Introducción: La leucoencefalopatía con sustancia blanca evanescente es una de las leucodistrofias más frecuentes. Generalmente inicia en la infancia y presenta un patrón de herencia autosómica recesiva. El 90% de los casos manifiesta mutaciones en uno de los genes que codifican para las cinco subunidades del factor de iniciación eucariótica 2 (EIF2B5). El diagnóstico se realiza por las manifestaciones clínicas, hallazgos en la resonancia magnética cerebral y estudios moleculares confirmatorios. Caso clínico: Paciente masculino de 13 meses con neurodesarrollo previo normal. Antecedente de internamiento por vómito, hipertermia, irritabilidad y rechazo a la vía oral de 15 días de evolución. Ante la exploración presentó perímetro cefálico y pares craneales normales. Se encontró hipotónico, con reflejos incrementados, sin datos meníngeos ni de cráneo hipertensivo. La tomografía de cráneo mostró hipodensidad generalizada de la sustancia blanca. Egresó sin recuperar deambulación. A los 15 días presentó somnolencia y crisis convulsivas focales después de traumatismo craneoencefálico. En la resonancia magnética se observó hipointensidad generalizada de sustancia blanca. Ante la sospecha de leucoencefalopatía con sustancia blanca evanescente, se solicitó la secuenciación del gen EIF2B5, que reportó mutación homocigota c.318A>T en el exón 2. El paciente requirió múltiples hospitalizaciones por hipertermia y descontrol de crisis convulsivas. Posteriormente mostró deterioro cognitivo, motor y pérdida de la agudeza visual. Falleció a los 6 años por neumonía severa. Conclusiones: Este caso contribuye a conocer el espectro de mutaciones que se presenta en pacientes mexicanos y permite ampliar el fenotipo asociado con esta mutación.


Abstract: Background: Vanishing white matter disease is one of the most frequent leukodystrophies in childhood with an autosomal recessive inheritance. A mutation in one of the genes encoding the five subunits of the eukaryotic initiation factor 2 (EIF2B5) is present in 90% of the cases. The diagnosis can be accomplished by the clinical and neuroradiological findings and molecular tests. Case report: We describe a thirteen-month-old male with previous normal neurodevelopment, who was hospitalized for vomiting, hyperthermia and irritability. On examination, cephalic perimeter and cranial pairs were normal. Hypotonia, increased muscle stretching reflexes, generalized white matter hypodensity on cranial tomography were found. Fifteen days after discharge, he suffered minor head trauma presenting drowsiness and focal seizures. Magnetic resonance showed generalized hypointensity of white matter. Vanishing white matter disease was suspected, and confirmed by sequencing of the EIF2B5 gene, revealing a homozygous c.318A> T mutation in exon 2. Subsequently, visual acuity was lost and cognitive and motor deterioration was evident. The patient died at six years of age due to severe pneumonia. Conclusions: This case contributes to the knowledge of the mutational spectrum present in Mexican patients and allows to extend the phenotype associated to this mutation.


Subject(s)
Child , Child, Preschool , Humans , Infant , Male , Eukaryotic Initiation Factor-2B/genetics , Leukoencephalopathies/diagnosis , Phenotype , Magnetic Resonance Imaging/methods , Tomography, X-Ray Computed/methods , Exons , Fatal Outcome , Leukoencephalopathies/physiopathology , Leukoencephalopathies/genetics , Mutation
8.
Bol Med Hosp Infant Mex ; 74(5): 364-369, 2017.
Article in Spanish | MEDLINE | ID: mdl-29382480

ABSTRACT

BACKGROUND: Vanishing white matter disease is one of the most frequent leukodystrophies in childhood with an autosomal recessive inheritance. A mutation in one of the genes encoding the five subunits of the eukaryotic initiation factor 2 (EIF2B5) is present in 90% of the cases. The diagnosis can be accomplished by the clinical and neuroradiological findings and molecular tests. CASE REPORT: We describe a thirteen-month-old male with previous normal neurodevelopment, who was hospitalized for vomiting, hyperthermia and irritability. On examination, cephalic perimeter and cranial pairs were normal. Hypotonia, increased muscle stretching reflexes, generalized white matter hypodensity on cranial tomography were found. Fifteen days after discharge, he suffered minor head trauma presenting drowsiness and focal seizures. Magnetic resonance showed generalized hypointensity of white matter. Vanishing white matter disease was suspected, and confirmed by sequencing of the EIF2B5 gene, revealing a homozygous c.318A> T mutation in exon 2. Subsequently, visual acuity was lost and cognitive and motor deterioration was evident. The patient died at six years of age due to severe pneumonia. CONCLUSIONS: This case contributes to the knowledge of the mutational spectrum present in Mexican patients and allows to extend the phenotype associated to this mutation.


Subject(s)
Eukaryotic Initiation Factor-2B/genetics , Leukoencephalopathies/diagnosis , Child , Child, Preschool , Exons , Fatal Outcome , Humans , Infant , Leukoencephalopathies/genetics , Leukoencephalopathies/physiopathology , Magnetic Resonance Imaging/methods , Male , Mutation , Phenotype , Tomography, X-Ray Computed/methods
9.
Gac Med Mex ; 151(2): 252-5, 2015.
Article in Spanish | MEDLINE | ID: mdl-25946536

ABSTRACT

Eczema herpeticum is an acute dermatoses caused by herpes simplex virus type 1 in atopic dermatitis patients, and is considered a dermatology emergency. Eczema herpeticum occurs in less than 3% of atopic patients. We report a patient with a history of atopic dermatitis who presented to an emergency department with eczema herpeticum. He was admitted and treated with antiviral medications with good outcome. We investigated filaggrin null mutations in the patient and his family and correlate them with the severity of the disease. We present the first Mexican patient with eczema herpeticum, atopic dermatitis and the presence of R501 X and 2282del4 filaggrin null mutations.


Subject(s)
Dermatitis, Atopic/complications , Dermatitis, Atopic/genetics , Intermediate Filament Proteins/genetics , Kaposi Varicelliform Eruption/complications , Mutation , Adolescent , Filaggrin Proteins , Humans , Male , Pedigree
10.
Cytokine ; 69(2): 180-8, 2014 Oct.
Article in English | MEDLINE | ID: mdl-24973688

ABSTRACT

Tumor necrosis factor alpha (TNF-α) is a proven modulator of adipose metabolism, but the mechanisms by which this cytokine affects the development and function of adipose tissue have not been fully elucidated to date. Using differential display analysis, in this study, we demonstrate that gene expression of the serine protease inhibitor A3g (SerpinA3g) is specifically induced in 3T3-F442A preadipocytes by TNF-α but not by other adipogenic inhibitors, such as retinoic acid (RA) or transforming growth factor type beta (TGF-ß). The specific induction of SerpinA3g by TNF-α was confirmed by RT-PCR in both preadipose and terminally differentiated 3T3-F442A cells. The knockdown of SerpinA3g using small interfering RNA prevented the antiadipogenesis elicited by TNF-α in 3T3-F442A cells but not the antiadipogenesis induced by RA or TGF-ß. SerpinA3g-silenced 3T3-F442A cells also did not display TNF-α-induced insulin resistance. Our results demonstrate that SerpinA3g is specifically induced by TNF-α in 3T3-F442A cells, regardless of their stage of differentiation, and participates in the antiadipogenesis and insulin resistance induced by this cytokine. Our results suggest that SerpinA3g plays a role in the TNF-α modulation of adipose tissue development and metabolism. Additional studies are warranted regarding the mechanisms mediating adipose SerpinA3g effects.


Subject(s)
Adipogenesis/drug effects , Insulin Resistance , Serpins/metabolism , Tumor Necrosis Factor-alpha/pharmacology , 3T3 Cells , Adipocytes/drug effects , Adipocytes/metabolism , Animals , Base Sequence , Mice , Molecular Sequence Data , Transforming Growth Factor beta/pharmacology , Tretinoin/pharmacology
11.
Biomed Opt Express ; 2(12): 3363-6, 2011 Dec 01.
Article in English | MEDLINE | ID: mdl-22162825

ABSTRACT

Knowledge of the existence of filaggrin (FLG) gene mutations might be helpful for a subclassification of patients with atopic dermatitis (AD) which can be used to introduce individualized treatments. In this work the filaggrin content in the skin is assessed using Raman spectroscopy and the results are compared to FLG genotyping of Mexican-mestizo patients. Results showed that the 2282del4 and R501X mutations present in the European population but absent in people of Asian or African descent are also present in the Mexican-mestizo population. The results also showed that patients with filaggrin gene mutations presented lower filaggrin concentrations measured using the vector correlation of their skin Raman spectra and a fixed spectrum of pure human recombinant filaggrin, these results indicate that Raman spectroscopy may be used as a noninvasive tool to detect FLG gene mutations.

12.
Neurochem Int ; 58(5): 574-81, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21300125

ABSTRACT

Epigenetic mechanisms are crucial to regulate the expression of different genes required for neuronal plasticity. Neurotoxic substances such as arsenic, which induces cognitive deficits in exposed children before any other manifestation of toxicity, could interfere with the epigenetic modulation of neuronal gene expression required for learning and memory. This study assessed in Wistar rats the effects that developmental arsenic exposure had on DNA methylation patterns in hippocampus and frontal cortex. Animals were exposed to arsenic in drinking water (3 and 36ppm) from gestation until 4 months of age, and DNA methylation in brain cells was determined by flow cytometry, immunohistochemistry and methylation-specific polymerase chain reaction (PCR) of the promoter regions of reelin (RELN) and protein phosphatase 1 (PP1) at 1, 2, 3 and 4 months of age. Immunoreactivity to 5 methyl-cytosine was significantly higher in the cortex and hippocampus of exposed animals compared to controls at 1 month, and DNA hypomethylation was observed the following months in the cortex at high arsenic exposure. Furthermore, we observed a significant increase in the non-methylated form of PP1 gene promoter at 2 and 3 months of age, either in cortex or hippocampus. In order to determine whether this exposure level is associated with memory deficits, a behavioral test was performed at the same age points, revealing progressive and dose-dependent deficits of fear memory. Our results demonstrate alterations of the methylation pattern of genes involved in neuronal plasticity in an animal model of memory deficit associated with arsenic exposure.


Subject(s)
Arsenic/toxicity , Brain/growth & development , CpG Islands/physiology , DNA Methylation/drug effects , DNA Methylation/physiology , Neuronal Plasticity/physiology , Age Factors , Animals , Arsenic/administration & dosage , Brain/drug effects , CpG Islands/drug effects , Female , Male , Neuronal Plasticity/drug effects , Promoter Regions, Genetic/drug effects , Promoter Regions, Genetic/physiology , Rats , Rats, Wistar , Reelin Protein
13.
J. physiol. biochem ; 66(2): 117-125, jun. 2010.
Article in English | IBECS | ID: ibc-122835

ABSTRACT

No disponible


The sodium–calcium exchanger (NCX) plays a major role in the regulation of cytosolic Ca2+ in muscle cells. In this work, we performed force experiments to explore the role of NCX during contraction and relaxation of Cch-stimulated guinea pig tracheal smooth muscle strips. This tissue showed low sensitivity to NCX inhibitor KB-R7943 (IC50, 57 ± 2 µM), although a complete relaxation was obtained by NCX inhibition at 100 µM. Interestingly, relaxation after washing the agonist was prolonged in the absence of external Na+, whereas washing without Na+ and in the presence of KB-R7943 resembled control conditions with physiological solution. Altogether, this suggests the reversal of NCX to a Ca2+ influx mode by the manipulation on the Na+ gradient, which can be inhibited by KB-R7943. In order to understand the low sensitivity to KB-R7943, we studied the molecular aspects of the NCX expressed in this tissue and found that the isoform of NCX expressed is 1.3, similar to that described in human tracheal smooth muscle. Sequencing revealed that amino acid 19 in exon B is phenylalanine, whereas in its human counterpart is leucine, and that the first amino acid after exon D is aspartate instead of glutamate in humans. Results herein presented are discussed in term of their possible functional implications in the exchanger activity and thus in airway physiology (AU)


Subject(s)
Humans , Guinea Pigs , Animals , Sodium-Calcium Exchanger/antagonists & inhibitors , Phenylalanine/analysis , Leucine/analysis , Aspartate Kinase/analysis , Glutamic Acid/analysis , Sodium-Calcium Exchanger , Guinea Pigs
14.
J Physiol Biochem ; 66(2): 117-25, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20428991

ABSTRACT

The sodium-calcium exchanger (NCX) plays a major role in the regulation of cytosolic Ca(2+) in muscle cells. In this work, we performed force experiments to explore the role of NCX during contraction and relaxation of Cch-stimulated guinea pig tracheal smooth muscle strips. This tissue showed low sensitivity to NCX inhibitor KB-R7943 (IC50, 57 +/- 2 microM), although a complete relaxation was obtained by NCX inhibition at 100 microM. Interestingly, relaxation after washing the agonist was prolonged in the absence of external Na(+), whereas washing without Na(+) and in the presence of KB-R7943 resembled control conditions with physiological solution. Altogether, this suggests the reversal of NCX to a Ca(2+) influx mode by the manipulation on the Na(+) gradient, which can be inhibited by KB-R7943. In order to understand the low sensitivity to KB-R7943, we studied the molecular aspects of the NCX expressed in this tissue and found that the isoform of NCX expressed is 1.3, similar to that described in human tracheal smooth muscle. Sequencing revealed that amino acid 19 in exon B is phenylalanine, whereas in its human counterpart is leucine, and that the first amino acid after exon D is aspartate instead of glutamate in humans. Results herein presented are discussed in term of their possible functional implications in the exchanger activity and thus in airway physiology.


Subject(s)
Muscle Contraction/drug effects , Sodium-Calcium Exchanger/metabolism , Thiourea/analogs & derivatives , Amino Acid Sequence , Animals , Base Sequence , Calcium/metabolism , Guinea Pigs , Male , Molecular Sequence Data , Muscle Relaxation/drug effects , Myocytes, Smooth Muscle/metabolism , Protein Isoforms/metabolism , Sodium-Calcium Exchanger/antagonists & inhibitors , Thiourea/pharmacology , Trachea/metabolism
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