RESUMEN
BACKGROUND: The transepithelial transport of electrolytes, solutes, and water in the kidney is a well-orchestrated process involving numerous membrane transport systems. Basolateral potassium channels in tubular cells not only mediate potassium recycling for proper Na+,K+-ATPase function but are also involved in potassium and pH sensing. Genetic defects in KCNJ10 cause EAST/SeSAME syndrome, characterized by renal salt wasting with hypokalemic alkalosis associated with epilepsy, ataxia, and sensorineural deafness. METHODS: A candidate gene approach and whole-exome sequencing determined the underlying genetic defect in eight patients with a novel disease phenotype comprising a hypokalemic tubulopathy with renal salt wasting, disturbed acid-base homeostasis, and sensorineural deafness. Electrophysiologic studies and surface expression experiments investigated the functional consequences of newly identified gene variants. RESULTS: We identified mutations in the KCNJ16 gene encoding KCNJ16, which along with KCNJ15 and KCNJ10, constitutes the major basolateral potassium channel of the proximal and distal tubules, respectively. Coexpression of mutant KCNJ16 together with KCNJ15 or KCNJ10 in Xenopus oocytes significantly reduced currents. CONCLUSIONS: Biallelic variants in KCNJ16 were identified in patients with a novel disease phenotype comprising a variable proximal and distal tubulopathy associated with deafness. Variants affect the function of heteromeric potassium channels, disturbing proximal tubular bicarbonate handling as well as distal tubular salt reabsorption.
Asunto(s)
Desequilibrio Ácido-Base/genética , Pérdida Auditiva Sensorineural/genética , Hipopotasemia/genética , Enfermedades Renales/genética , Canales de Potasio de Rectificación Interna/genética , Adolescente , Adulto , Alelos , Animales , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Túbulos Renales , Mutación con Pérdida de Función , Masculino , Ratones , Nefronas/metabolismo , Oocitos , Linaje , Fenotipo , ARN Mensajero/metabolismo , Reabsorción Renal/genética , Sales (Química)/metabolismo , Secuenciación del Exoma , Xenopus laevis , Adulto JovenRESUMEN
The crystal structure of the dimeric membrane domain of human Band 3(1), the red cell chloride/bicarbonate anion exchanger 1 (AE1, SLC4A1), provides a structural context for over four decades of studies into this historic and important membrane glycoprotein. In this review, we highlight the key structural features responsible for anion binding and translocation and have integrated the following topological markers within the Band 3 structure: blood group antigens, N-glycosylation site, protease cleavage sites, inhibitor and chemical labeling sites, and the results of scanning cysteine and N-glycosylation mutagenesis. Locations of mutations linked to human disease, including those responsible for Southeast Asian ovalocytosis, hereditary stomatocytosis, hereditary spherocytosis, and distal renal tubular acidosis, provide molecular insights into their effect on Band 3 folding. Finally, molecular dynamics simulations of phosphatidylcholine self-assembled around Band 3 provide a view of this membrane protein within a lipid bilayer.
Asunto(s)
Desequilibrio Ácido-Base/sangre , Acidosis Tubular Renal/sangre , Anemia Hemolítica Congénita/sangre , Proteína 1 de Intercambio de Anión de Eritrocito/química , Eliptocitosis Hereditaria/sangre , Errores Innatos del Metabolismo/sangre , Esferocitosis Hereditaria/sangre , Ácido 4,4'-Diisotiocianostilbeno-2,2'-Disulfónico/farmacología , Desequilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/patología , Acidosis Tubular Renal/genética , Acidosis Tubular Renal/patología , Anemia Hemolítica Congénita/genética , Anemia Hemolítica Congénita/patología , Proteína 1 de Intercambio de Anión de Eritrocito/antagonistas & inhibidores , Proteína 1 de Intercambio de Anión de Eritrocito/genética , Proteína 1 de Intercambio de Anión de Eritrocito/metabolismo , Bicarbonatos/metabolismo , Eliptocitosis Hereditaria/genética , Eliptocitosis Hereditaria/patología , Eritrocitos/efectos de los fármacos , Eritrocitos/metabolismo , Eritrocitos/patología , Eritrocitos Anormales/patología , Expresión Génica , Glicosilación , Humanos , Ligandos , Errores Innatos del Metabolismo/genética , Errores Innatos del Metabolismo/patología , Mutación , Unión Proteica , Esferocitosis Hereditaria/genética , Esferocitosis Hereditaria/patologíaAsunto(s)
Desequilibrio Ácido-Base/genética , Anemia Hemolítica Congénita/genética , Eritrocitos Anormales/patología , Errores Innatos del Metabolismo/genética , Sistema del Grupo Sanguíneo Rh-Hr/genética , Desequilibrio Ácido-Base/patología , Adulto , Anemia Hemolítica Congénita/patología , Proteínas Sanguíneas/genética , Eritrocitos Anormales/metabolismo , Femenino , Humanos , Glicoproteínas de Membrana/genética , Errores Innatos del Metabolismo/patología , EmbarazoRESUMEN
Transmembrane lipid transporters are believed to establish and maintain phospholipid asymmetry in biological membranes; however, little is known about the in vivo function of the specific transporters involved. Here, we report that developing erythrocytes from mice lacking the putative phosphatidylserine flippase ATP11C showed a lower rate of PS translocation in vitro compared with erythrocytes from wild-type littermates. Furthermore, the mutant mice had an elevated percentage of phosphatidylserine-exposing mature erythrocytes in the periphery. Although erythrocyte development in ATP11C-deficient mice was normal, the mature erythrocytes had an abnormal shape (stomatocytosis), and the life span of mature erythrocytes was shortened relative to that in control littermates, resulting in anemia in the mutant mice. Thus, our findings uncover an essential role for ATP11C in erythrocyte morphology and survival and provide a new candidate for the rare inherited blood disorder stomatocytosis with uncompensated anemia.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Membrana Eritrocítica/enzimología , Fosfolípidos/metabolismo , Desequilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/metabolismo , Desequilibrio Ácido-Base/patología , Adenosina Trifosfatasas/genética , Anemia Hemolítica Congénita/genética , Anemia Hemolítica Congénita/metabolismo , Anemia Hemolítica Congénita/patología , Animales , Transporte Biológico Activo , Supervivencia Celular/fisiología , Membrana Eritrocítica/genética , Eritrocitos Anormales/metabolismo , Eritrocitos Anormales/patología , Errores Innatos del Metabolismo/genética , Errores Innatos del Metabolismo/metabolismo , Errores Innatos del Metabolismo/patología , Ratones , Ratones Mutantes , Fosfolípidos/genéticaRESUMEN
The mammalian collecting duct comprises principal and intercalated cells, which maintain sodium/water and acid/base balance, respectively, but the epigenetic contributors to the differentiation of these cell types remain unknown. Here, we investigated whether the histone H3 K79 methyltransferase Dot1l, which is highly expressed in principal cells, participates in this process. Taking advantage of the distribution of aquaporin 2 (Aqp2), which localizes to principal cells of the collecting duct, we developed mice lacking Dot1l in Aqp2-expressing cells (Dot1l(AC)) and found that these mice had approximately 20% fewer principal cells and 13%-16% more intercalated cells than control mice. This deletion of Dot1l in principal cells abolished histone H3 K79 methylation in these cells, but unexpectedly, most intercalated cells also had undetectable di-methyl K79, suggesting that Aqp2(+) cells give rise to intercalated cells. These Aqp2(+) cell-derived intercalated cells were present in both developing and mature kidneys. Furthermore, compared with control mice, Dot1l(AC) mice had 40% higher urine volume and 18% lower urine osmolarity with relatively normal electrolyte and acid-base homeostasis. In conclusion, these data suggest that Dot1l deletion facilitates the differentiation of some α- and ß-intercalated cells from Aqp2-expressing progenitor cells or mature principal cells.
Asunto(s)
Acuaporina 2/genética , Túbulos Renales Colectores/citología , Túbulos Renales Colectores/fisiología , Metiltransferasas/genética , Equilibrio Hidroelectrolítico/genética , Desequilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/patología , Desequilibrio Ácido-Base/fisiopatología , Animales , Acuaporina 2/metabolismo , Diferenciación Celular/fisiología , Linaje de la Célula/fisiología , Epigénesis Genética/fisiología , Femenino , N-Metiltransferasa de Histona-Lisina , Histonas/metabolismo , Integrasas/genética , Masculino , Metilación , Metiltransferasas/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Poliuria/genética , Poliuria/patología , Poliuria/fisiopatología , Desequilibrio Hidroelectrolítico/genética , Desequilibrio Hidroelectrolítico/patología , Desequilibrio Hidroelectrolítico/fisiopatologíaRESUMEN
BACKGROUND: Four genes responsible for pseudohypoaldosteronism type II (PHA-II) have been identified, thereby facilitating molecular diagnostic testing. CASE-DIAGNOSIS/TREATMENT: A 1-year-old boy with prolonged hyperkalemia, metabolic acidosis, hyperchloremia, growth delay, and mild hypertension was diagnosed with PHA-II based on the detection of exon 9 skipping in CUL3 mRNA. The impaired splicing was the result of a de novo, previously unreported single nucleotide substitution in the splice acceptor site of CUL3 intron 8. Among the four genes reported to be involved in PHA-II, CUL3 was the primary suspect in our patient because in patients with the CUL3 mutation, the onset of disease is often early in infancy and the phenotypes of PHA-II are more severe. Our patient was treated with trichlormethiazide, which inhibits the function of the sodium-chloride co-transporter (NCC), and the outcome was favorable, with correction of body fluids and blood electrolyte homeostasis. CONCLUSION: Since chronic acidosis and hypertension associated with PHA-II can result in delayed growth and development in pediatric patients, genetic analysis to detect the CUL3 mutation and to enable intervention early in the disease course would be beneficial for infants with suspected PHA-II.
Asunto(s)
Proteínas Cullin/genética , Seudohipoaldosteronismo/genética , Desequilibrio Ácido-Base/sangre , Desequilibrio Ácido-Base/genética , Acidosis/etiología , Acidosis/terapia , Bicarbonatos/sangre , Presión Sanguínea/fisiología , Cloruros/sangre , Diuréticos/uso terapéutico , Exones/genética , Pruebas Genéticas , Humanos , Lactante , Intrones/genética , Masculino , Potasio/sangre , Seudohipoaldosteronismo/diagnóstico , Seudohipoaldosteronismo/terapia , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Triclormetiazida/uso terapéuticoRESUMEN
Disorders of water balance lead either to dehydration or overhydration. Because there is an intimate relationship between water and sodium concentration (water generally following salt), one can distinguish hypotonic, isotonic and hypertonic dehydration and the same for overhydration. The vast majority of water balance disorders are acquired. In this article, the focus is on the inherited disorders both of water (nephrogenic diabetes insipidus) and acid-base balance. Both acidosis and alkalosis can arise from primary tubular ion transport abnormalities. The alkaloses are usually secondary to salt handling problems, whereas the renal tubular acidoses are often a consequence of primary abnormalities of acid-base transporters.
Asunto(s)
Desequilibrio Ácido-Base/genética , Síndrome de Fanconi/genética , Predisposición Genética a la Enfermedad/genética , Homeostasis/genética , Enfermedades Renales/genética , Túbulos Renales Proximales/fisiopatología , Animales , Genotipo , Humanos , Modelos GenéticosRESUMEN
Male mice deficient in ESR1 (ERalpha) (Esr1KO mice) are infertile, and sperm recovered from the cauda epididymis exhibit reduced motility and fail to fertilize eggs in vitro. These effects on sperm appear to result from defective epididymal function and not a direct effect on spermatogenesis, as Esr1KO germ cells transplanted into wild-type testes yield normal offspring. We hypothesized that the previously described defect in efferent duct fluid reabsorption would lead to alterations in the epididymal fluid milieu, which would negatively impact sperm function. Analysis of the epididymal fluid revealed that the Esr1KO maintains a higher luminal pH throughout the epididymis, confirming an inability of the efferent ducts and/or epididymis to properly acidify the luminal contents. Subsequent studies showed that these abnormalities were not the result of global defects in epididymal function since protein secretion by the Esr1KO epididymis appeared normal as judged by SDS-PAGE of total secreted proteins and by immunoblotting of candidate secreted proteins. To gain insight into the basis of the aberrant fluid homeostasis in the Esr1KO epididymis, the expression of several enzymes and transporters known to be involved in acid/base regulation were analyzed. The levels of SLC9A3 (NHE3) as well as carbonic anhydrase XIV and SLC4A4 (NBC1) were all reduced in the proximal portion of the Esr1KO epididymis, while other components appeared unaffected, including other ion transporters and ATP6V0A1 (V-ATPase). The altered luminal milieu of the Esr1KO epididymis was shown to lead to a corresponding increase in the intracellular pH of Esr1KO sperm, relative to sperm from control animals. Since pH and bicarbonate ions are critical regulators of sperm cAMP levels and motility, we attempted to bypass the abnormal luminal and intracellular environment by supplementing sperm with exogenous cAMP. This treatment rescued all defective motility parameters, as assayed by CASA, further showing that motility defects are not intrinsic to the sperm but, rather, result from the abnormal epididymal milieu.
Asunto(s)
Desequilibrio Ácido-Base/metabolismo , Proteínas Secretorias del Epidídimo/metabolismo , Epidídimo/metabolismo , Receptor alfa de Estrógeno/metabolismo , Motilidad Espermática/fisiología , Desequilibrio Ácido-Base/genética , Animales , AMP Cíclico/metabolismo , Receptor alfa de Estrógeno/genética , Concentración de Iones de Hidrógeno , Masculino , Ratones , Ratones Noqueados , Ratones Transgénicos , Maduración del Esperma/fisiología , Transporte Espermático/fisiología , Espermatozoides/metabolismoRESUMEN
Overhydrated stomatocytosis is a rare autosomal dominant disorder known to cause variably severe haemolytic anaemia due to heterozygous mutations in the RHAG gene. We report a 26-year-old man with recurring jaundice, splenohepatomegaly and mild chronic haemolytic anaemia with significant stomatocytosis. Extensive haemolytic work-up including flow cytometry for eosin-5'-maleimide and CD47 expression levels was carried out. Targeted resequencing revealed two probably causative heterozygous mutations in RHAG (Leu336Ser and Ile149Met) and one heterozygous mutation in ANK1 (Glu1046Lys). RHAG involvement was confirmed by decreased RhAG macrocomplex component indicated by the reduced CD47 expression on erythrocytes. In silico analysis concordantly flagged RHAG:Leu336Ser and ANK1:Glu1046Lys as likely deleterious mutation, whereas RHAG:Ile149Met was reported as likely neutral by PROVEAN. Family screening by Sanger sequencing revealed RHAG:Leu336Ser in a mother and ANK1:Glu1046Lys in a father who were both asymptomatic, excluding them as causative dominant events, thus establishing RHAG:Ile149Met, novel de novo mutation as probably causative. This case illustrates the importance of family screening in interpreting next-generation sequencing (NGS) data, as in silico analysis alone can be misleading. Erudite generation of diagnostic possibilities based on a thorough baseline clinical and laboratory work-up remains as important as ever, even as NGS brings about a paradigm shift in the diagnostic work-up of rare haemolytic anaemias.
Asunto(s)
Desequilibrio Ácido-Base/genética , Anemia Hemolítica Congénita/genética , Proteínas Sanguíneas/genética , Glicoproteínas de Membrana/genética , Errores Innatos del Metabolismo/genética , Mutación , Desequilibrio Ácido-Base/sangre , Desequilibrio Ácido-Base/diagnóstico , Adulto , Anemia Hemolítica Congénita/sangre , Anemia Hemolítica Congénita/diagnóstico , Análisis Mutacional de ADN/métodos , Recuento de Eritrocitos , Eritrocitos Anormales , Femenino , Predisposición Genética a la Enfermedad , Herencia , Heterocigoto , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Errores Innatos del Metabolismo/sangre , Errores Innatos del Metabolismo/diagnóstico , Linaje , FenotipoRESUMEN
Significant advances have been made in our understanding of the structural basis for altered cell function in various inherited red cell membrane disorders with reduced red cell survival and resulting hemolytic anemia. The current review summarizes these advances as they relate to defining the molecular and structural basis for disorders involving altered membrane structural organization (hereditary spherocytosis [HS] and hereditary elliptocytosis [HE]) and altered membrane transport function (hereditary overhydrated stomatocytosis and hereditary xerocytosis). Mutations in genes encoding membrane proteins that account for these distinct red cell phenotypes have been identified. These molecular insights have led to improved understanding of the structural basis for altered membrane function in these disorders. Weakening of vertical linkage between the lipid bilayer and spectrin-based membrane skeleton leads to membrane loss in HS. In contrast, weakening of lateral linkages among different skeletal proteins leads to membrane fragmentation and decreased surface area in HE. The degrees of membrane loss and resultant increases in cell sphericity determine the severity of anemia in these two disorders. Splenectomy leads to amelioration of anemia by increasing the circulatory red cell life span of spherocytic red cells that are normally sequestered by the spleen. Disordered membrane cation permeability and resultant increase or decrease in red cell volume account for altered cellular deformability of hereditary overhydrated stomatocytosis and hereditary xerocytosis, respectively. Importantly, splenectomy is not beneficial in these two membrane transport disorders and in fact contraindicated due to severe postsplenectomy thrombotic complications.
Asunto(s)
Desequilibrio Ácido-Base , Anemia Hemolítica Congénita , Eliptocitosis Hereditaria , Membrana Eritrocítica , Hidropesía Fetal , Errores Innatos del Metabolismo , Esferocitosis Hereditaria , Desequilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/metabolismo , Desequilibrio Ácido-Base/patología , Desequilibrio Ácido-Base/terapia , Anemia Hemolítica Congénita/genética , Anemia Hemolítica Congénita/metabolismo , Anemia Hemolítica Congénita/patología , Anemia Hemolítica Congénita/terapia , Eliptocitosis Hereditaria/genética , Eliptocitosis Hereditaria/metabolismo , Eliptocitosis Hereditaria/patología , Eliptocitosis Hereditaria/terapia , Membrana Eritrocítica/genética , Membrana Eritrocítica/metabolismo , Membrana Eritrocítica/patología , Eritrocitos Anormales/metabolismo , Eritrocitos Anormales/patología , Humanos , Hidropesía Fetal/genética , Hidropesía Fetal/metabolismo , Hidropesía Fetal/patología , Hidropesía Fetal/terapia , Errores Innatos del Metabolismo/genética , Errores Innatos del Metabolismo/metabolismo , Errores Innatos del Metabolismo/patología , Errores Innatos del Metabolismo/terapia , Mutación , Espectrina/genética , Espectrina/metabolismo , Esferocitosis Hereditaria/genética , Esferocitosis Hereditaria/metabolismo , Esferocitosis Hereditaria/patología , Esferocitosis Hereditaria/terapiaRESUMEN
The kidney is essential in maintaining body acid-base status. Recently, the use of transgenic mice has largely contributed to the understanding of the mechanisms involved. Important issues have been addressed in terms of the function of proteins or their regulation. In the proximal tubule, the role of Na+/HCO3-cotransport has been established, although further studies are needed to understand how its mutations lead to renal disease. Na+/H+ exchange has also been extensively studied, and its role in diuretic and natriuretic responses following an increase in blood pressure has been elucidated. The interaction of other transport proteins, such as the Na+/phosphate cotransporter NaPi II-a, with the Na+/H+ exchanger has also been investigated. In the medullary thick ascending limb of Henle's loop (MTAL), a role for NHE1 in transepithelial HCO3- absorption has been demonstrated: basolateral NHE1 controls the function of apical NHE3. As for the distal nephron, the majority of observations suggest that the regulation of H+-ATPase activity in response to acid-base status is mediated by the trafficking of pumps or pump sub-units, especially for the a4 subunit, rather than changes in subunit expression levels. Furthermore, the function of pendrin, a chloride/anion exchanger, has been assessed in response to changes in acid-base status. Important results have been obtained regarding the regulation of proximal tubule transport by several mechanisms, such as microvilli changes and the inducible and endothelial isoform of nitric oxide synthase (NOS). Finally, the interaction of chloride channels and potassium-chloride cotransporter with proton secretion has been evaluated. These findings highlight the importance of knockout animal models in studying kidney regulation of acid-base balance.
Asunto(s)
Equilibrio Ácido-Base/fisiología , Desequilibrio Ácido-Base/genética , ADN/genética , Expresión Génica , Intercambiadores de Sodio-Hidrógeno/genética , Desequilibrio Ácido-Base/metabolismo , Animales , Proteínas de Transporte de Catión/genética , Proteínas de Transporte de Catión/metabolismo , Modelos Animales de Enfermedad , Túbulos Renales/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Ratones , Ratones Transgénicos , Óxido Nítrico Sintasa/genética , Óxido Nítrico Sintasa/metabolismo , Simportadores de Sodio-Bicarbonato/genética , Simportadores de Sodio-Bicarbonato/metabolismo , Intercambiador 1 de Sodio-Hidrógeno , Intercambiador 3 de Sodio-Hidrógeno , Intercambiadores de Sodio-Hidrógeno/metabolismoRESUMEN
The inherited metabolic disease propionic acidemia (PA) can result from mutations in either of the genes PCCA or PCCB, which encode the alpha and beta subunits, respectively, of the mitochondrial enzyme propionyl CoA-carboxylase. In this work we have analyzed the molecular basis of PCCA gene defects, studying mRNA levels and identifying putative disease causing mutations. A total of 10 different mutations, none predominant, are present in a sample of 24 mutant alleles studied. Five novel mutations are reported here for the first time. A neutral polymorphism and a variant allele present in the general population were also detected. To examine the effect of a point mutation (M348K) involving a highly conserved residue, we have carried out in vitro expression of normal and mutant PCCA cDNA and analyzed the mitochondrial import and stability of the resulting proteins. Both wild-type and mutant proteins were imported into mitochondria and processed into the mature form with similar efficiency, but the mature mutant M348K protein decayed more rapidly than did the wild-type, indicating a reduced stability, which is probably the disease-causing mechanism.
Asunto(s)
Desequilibrio Ácido-Base/genética , Carboxiliasas/deficiencia , Mutación , Propionatos/sangre , Desequilibrio Ácido-Base/sangre , Animales , Northern Blotting , Carboxiliasas/biosíntesis , Carboxiliasas/genética , Clonación Molecular , Codón sin Sentido , ADN Complementario/biosíntesis , Humanos , Metilmalonil-CoA Descarboxilasa , Mitocondrias Hepáticas/metabolismo , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa InversaAsunto(s)
Desequilibrio Ácido-Base/diagnóstico , Alcalosis/diagnóstico , Alcalosis/fisiopatología , Síndrome de Liddle/diagnóstico , Desequilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/fisiopatología , Alcalosis/genética , Electrólitos/metabolismo , Canales Epiteliales de Sodio/genética , Femenino , Mutación del Sistema de Lectura/genética , Homeostasis/fisiología , Humanos , Concentración de Iones de Hidrógeno , Síndrome de Liddle/genética , Síndrome de Liddle/fisiopatología , Adulto JovenRESUMEN
Maintaining acid base balance presents a considerable challenge to the growing neonate. The infant must ingest protein for growth and development. The metabolism of sulfur containing amino acids leads to the production of protons that must be secreted by the kidney. In addition, the formation of hydroxyapatite for the mineralization of growing bone also leads to acid production. Thus, the growing infant must excrete approximately 2 to 3 mEq of acid per kilogram of body weight per day to avoid becoming acidotic. The mechanisms for excreting acid undergo complex maturational changes that predispose the neonate, and the premature neonate in particular, to a great risk for the development of acidosis. In addition, infants are susceptible to gastrointestinal disturbances that can lead to acidosis due to acute loss of bicarbonate in the stool. The kidney is then responsible for the production of new bicarbonate to restore the body's acid base balance. There are also a number of inherited disorders in the kidney that affect acid secretion and lead to acid base disturbances in neonates. This review discusses the mechanisms by which the kidney is capable of excreting acid as well as the developmental regulation of these processes and the basis of inherited disorders of acidification.
Asunto(s)
Equilibrio Ácido-Base/fisiología , Desequilibrio Ácido-Base , Desequilibrio Ácido-Base/etiología , Desequilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/fisiopatología , Humanos , Recién NacidoRESUMEN
The paper describes the results obtained for differential diagnostics of substantially complex disorders in the acid-base status. Since the first attempts of applying the genetic programming to this problem, presented by the authors at MIE 2000, proved promising, the investigation has been continued. The goal of the present study is to create computer genetic programs which, while taking into account a set of laboratory gasometric and electrolyte measurements, would be able to assist the diagnostics of acid-base disorders. Seven (7) single acid-base disorders, eleven (11) double acid-base disorders and six (6) triple complicated disorders with accompanying anion gap alterations are approached in the study. A set of simulated laboratory measurements has been prepared, providing 250 results for the evaluation of the fitness function of the designed genetic computer programs, plus some additional results for testing. The final results are presented in the form of a confusion matrix for the testing data, which shows that the developed system may be helpful in clinical practice.
Asunto(s)
Equilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/genética , Pruebas Genéticas/métodos , Desequilibrio Ácido-Base/diagnóstico , Algoritmos , Diagnóstico por Computador , Diagnóstico Diferencial , Sistemas Especialistas , Humanos , Diseño de SoftwareRESUMEN
Differential diagnostics of very complex disorders in the acid-base status and in the accompanying electrolyte balance belongs to the most difficult diagnostic procedures in clinical practice. The goal of our study was to create computer genetic programs, able to aid the diagnostics of acid-base disorders, taking into account a set of laboratory gasometric and electrolyte measurements. Seven (7) single acid-base disorders, eleven (11) double acid-base disorders and six (6) triple complicated disorders with accompanying anion gap alterations were approached by our study. A set of simulated laboratory measurements was prepared, providing 250 results for the evaluation of the fitness function of the designed computer genetic programs, plus some additional results for testing.
Asunto(s)
Equilibrio Ácido-Base/genética , Desequilibrio Ácido-Base/genética , Diagnóstico por Computador , Programas Informáticos , Desequilibrio Ácido-Base/diagnóstico , Inteligencia Artificial , Diagnóstico Diferencial , Sistemas Especialistas , HumanosRESUMEN
Piezo has recently been identified as a family of eukaryotic mechanosensitive channels composed of subunits containing over 2,000 amino acids, without recognizable sequence similarity to other channels. Here, we present the crystal structure of a large, conserved extramembrane domain located just before the last predicted transmembrane helix of C. elegans PIEZO, which adopts a topologically distinct ß sandwich fold. The structure was also determined of a point mutation located on a conserved surface at the position equivalent to the human PIEZO1 mutation found in dehydrated hereditary stomatocytosis patients (M2225R). While the point mutation does not change the overall domain structure, it does alter the surface electrostatic potential that may perturb interactions with a yet-to-be-identified ligand or protein. The lack of structural similarity between this domain and any previously characterized fold, including those of eukaryotic and bacterial channels, highlights the distinctive nature of the Piezo family of eukaryotic mechanosensitive channels.
Asunto(s)
Proteínas de Caenorhabditis elegans/química , Canales Iónicos/química , Pliegue de Proteína , Desequilibrio Ácido-Base/genética , Secuencia de Aminoácidos , Anemia Hemolítica Congénita/genética , Proteínas de Caenorhabditis elegans/metabolismo , Secuencia Conservada , Cristalografía por Rayos X , Proteínas de Drosophila/química , Proteínas de Drosophila/genética , Eritrocitos Anormales , Humanos , Canales Iónicos/genética , Canales Iónicos/metabolismo , Errores Innatos del Metabolismo/genética , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Estructura Terciaria de ProteínaRESUMEN
BACKGROUND: Cystic fibrosis (CF) is caused by a misfunctional CF transmembrane conductance regulator (CFTR) protein, which is believed to contributes to the regulation of the airway surface liquid (ASL) pH. This study investigated acid and base secretion in freshly excised human nasal tissues from CF patients homozygous for the ΔF508 mutation. METHODS: Human nasal mucosa was collected during sinus surgery and investigated in Ussing chambers. Mucosal equilibrium pH values and rate of acid and base secretion were determined using the pH-stat technique. RESULTS: The equilibrium pH of nasal epithelia from ΔF508 CF patients with chronic rhinosinusitis (CRS) was pH = 7.08 ± 0.09 and was significantly lower compared to nasal epithelia from CRS patients without CF (pH = 7.33 ± 0.06) and normal subjects (pH = 7.34 ± 0.08, n = 6). The rate of base secretion in CF nasal tissues was 11.8 ± 2.4 nmol · min(−1) · cm(−2), which was significantly lower than normal (57.2 ± 9.2 nmol · min(−1) · cm(−2)). The HCO3(−) secretory rate was further increased by forskolin by 16.1% in normal, but not in CF tissues. CONCLUSION: Our data suggests that CF patients exhibited significantly lower base secretion by the nasal airway epithelium. It is possible that improper regulation of ASL pH in CF may negatively impact the innate host defense system.
Asunto(s)
Desequilibrio Ácido-Base/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Mutación/genética , Mucosa Nasal/metabolismo , Ácidos/metabolismo , Adulto , Análisis de Varianza , Bicarbonatos/metabolismo , Líquidos Corporales/química , Estudios de Casos y Controles , Enfermedad Crónica , Fibrosis Quística/metabolismo , Femenino , Homocigoto , Humanos , Concentración de Iones de Hidrógeno , Masculino , Protones , Rinitis/metabolismo , Sinusitis/metabolismoRESUMEN
In situations where the cause of hypokalemia is not obvious, measurement of urinary potassium excretion and blood pressure and assessment of acid-base balance are often helpful. A random urine potassium-creatinine ratio (K/C) less than 1.5 suggests poor intake, gastrointestinal losses, or a shift of potassium into cells. If hypokalemia is associated with paralysis, we should consider hyperthyroidism, familial or sporadic periodic paralysis. Metabolic acidosis with a urine K/C ratio less than 1.5 suggests lower gastrointestinal losses due to diarrhea or laxative abuse. Metabolic acidosis with K/C ratio of 1.5 higher is often due to diabetic ketoacidosis or type 1 or type 2 distal renal tubular acidosis. Metabolic alkalosis with a K/C ratio less than 1.5 and a normal blood pressure is often due to surreptitious vomiting. Metabolic alkalosis with a higher K/C ratio and a normal blood pressure suggests diuretic use, Bartter syndrome, or Gitelman syndrome. Metabolic alkalosis with a high urine K/C ratio and hypertension suggests primary hyperaldosteronism, Cushing syndrome, congenital adrenal hyperplasia, renal artery stenosis, apparent mineralocorticoid excess, or Liddle syndrome. Hypomagnesemia can lead to increased urinary potassium losses and hypokalemia. The differential rests upon measurement of blood magnesium, aldosterone and renin levels, diuretic screen in urine, response to spironolactone and amiloride, measurement of plasma cortisol level and the urinary cortisol-cortisone ratio, and genetic testing.
Asunto(s)
Desequilibrio Ácido-Base/diagnóstico , Hipertensión/complicaciones , Hipopotasemia/complicaciones , Hipopotasemia/diagnóstico , Desequilibrio Ácido-Base/complicaciones , Desequilibrio Ácido-Base/genética , Algoritmos , Creatinina/sangre , Creatinina/orina , Humanos , Hipertensión/etiología , Hipertensión/genética , Hipopotasemia/genética , Potasio/sangre , Potasio/orinaRESUMEN
Inherited acidosis may result from a primary renal defect in acid-base handling, emphasizing the central role of the kidney in control of body pH; as a secondary phenomenon resulting from abnormal renal electrolyte handling; or from excess production of acid elsewhere in the body. Here, we review our current understanding of the inherited renal acidoses at a genetic and molecular level.