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1.
Adv Rheumatol ; 59: 20, 2019. tab
Article in English | LILACS | ID: biblio-1088591

ABSTRACT

Abstract Background: To date there are no specific classification criteria for childhood-onset systemic lupus erythematosus (cSLE). This study aims to compare the performance among the American College of Rheumatology (ACR) 1997, the Systemic Lupus International Collaborating Clinics criteria (SLICC) and the new European League Against Rheumatism (EULAR)/ACR criteria, in a cSLE cohort. Methods: We conducted a medical chart review study of cSLE cases and controls with defined rheumatic diseases, both ANA positive, to establish each ACR1997, SLICC and EULAR/ACR criterion fulfilled, at first visit and 1-year-follow-up. Results: Study population included 122 cSLE cases and 89 controls. At first visit, SLICC criteria had higher sensitivity than ACR 1997 (89.3% versus 70.5%, p < 0.001), but similar specificity (80.9% versus 83.2%, p = 0.791), however performance was not statistically different at 1-year-follow-up. SLICC better scored in specificity compared to EULAR/ACR score ≥ 10 at first visit (80.9% versus 67.4%, p = 0.008) and at 1-year (76.4% versus 58.4%, p = 0.001), although sensitivities were similar. EULAR/ACR criteria score ≥ 10 exhibited higher sensitivity than ACR 1997 (87.7% versus 70.5%, p < 0.001) at first visit, but comparable at 1-year, whereas specificity was lower at first visit (67.4% versus 83.2%, p = 0.004) and 1-year (58.4% versus 76.4%, p = 0.002). A EULAR/ACR score ≥ 13 against a score ≥ 10, resulted in higher specificity, positive predictive value, and cut-off point accuracy. Compared to SLICC, a EULAR/ACR score ≥ 13 resulted in lower sensitivity at first visit (76.2% versus 89.3%, p < 0.001) and 1-year (91% versus 97.5%, p = 0.008), but similar specificities at both assessments. When compared to ACR 1997, a EULAR/ACR total score ≥ 13, resulted in no differences in sensitivity and specificity at both observation periods. Conclusions: In this cSLE population, SLICC criteria better scored at first visit and 1-year-follow-up. The adoption of a EULAR/ACR total score ≥ 13 in this study, against the initially proposed ≥10 score, was most appropriate to classify cSLE. Further studies are necessary to address if SLICC criteria might allow fulfillment of cSLE classification earlier in disease course and may be more inclusive of cSLE subjects for clinical studies.


Subject(s)
Animals , Humans , Brain/metabolism , Pharmaceutical Preparations/metabolism , Blood-Brain Barrier/metabolism , Tissue Distribution/physiology , Models, Theoretical , Arachnoid/drug effects , Arachnoid/metabolism , Biological Transport/drug effects , Biological Transport/physiology , Brain/drug effects , Pharmaceutical Preparations/administration & dosage , Blood-Brain Barrier/drug effects , Tissue Distribution/drug effects , Extracellular Fluid/drug effects , Extracellular Fluid/metabolism
2.
Biol. Res ; 51: 4, 2018. tab, graf
Article in English | LILACS | ID: biblio-888434

ABSTRACT

Abstract Aquaporins (AQP) are channel proteins belonging to the Major Intrinsic Protein (MIP) superfamily that play an important role in plant water relations. The main role of aquaporins in plants is transport of water and other small neutral molecules across cellular biological membranes. AQPs have remarkable features to provide an efficient and often, specific water flow and enable them to transport water into and out of the cells along the water potential gradient. Plant AQPs are classified into five main subfamilies including the plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodulin 26 like intrinsic proteins (NIPs), small basic intrinsic proteins (SIPs) and X intrinsic proteins (XIPs). AQPs are localized in the cell membranes and are found in all living cells. However, most of the AQPs that have been described in plants are localized to the tonoplast and plasma membranes. Regulation of AQP activity and gene expression, are also considered as a part of the adaptation mechanisms to stress conditions and rely on complex processes and signaling pathways as well as complex transcriptional, translational and posttranscriptional factors. Gating of AQPs through different mechanisms, such as phosphorylation, tetramerization, pH, cations, reactive oxygen species, phytohormones and other chemical agents, may play a key role in plant responses to environmental stresses by maintaining the uptake and movement of water in the plant body.


Subject(s)
Plants/metabolism , Stress, Physiological/physiology , Biological Transport/physiology , Aquaporins/metabolism , Gene Expression , Aquaporins/physiology
3.
Int. arch. otorhinolaryngol. (Impr.) ; 19(1): 80-85, Jan-Mar/2015. tab, graf
Article in English | LILACS | ID: lil-741526

ABSTRACT

Introduction Obstructive sleep apnea syndrome affects up to 4% of middle-aged men and 2% of adult women. It is associated with obesity. Objective The objective of this article is to review the literature to determine which factors best correlate with treatment success in patients with obstructive sleep apnea syndrome treated with a mandibular repositioning appliance. Data Synthesis A search was performed of the PubMed, Cochrane, Lilacs, Scielo, and Web of Science databases of articles published from January 1988 to January 2012. Two review authors independently collected data and assessed trial quality. Sixty-nine articles were selected from PubMed and 1 from Cochrane library. Of these, 42 were excluded based on the title and abstract, and 27 were retrieved for complete reading. A total of 13 articles and 1 systematic review were considered eligible for further review and inclusion in this study: 6 studies evaluated anthropomorphic and physiologic factors, 3 articles addressed cephalometric and anatomic factors, and 4 studies evaluated variables related to mandibular repositioning appliance design and activation. All the studies evaluated had low to moderate methodologic quality and were not able to support evidence on prediction of treatment success. Conclusion Based on this systematic review on obstructive sleep apnea syndrome treatment, it remains unclear which predictive factors can be used with confidence to select patients suitable for treatment with a mandibular repositioning appliance. .


Subject(s)
Animals , Biological Evolution , Carrier Proteins/chemistry , Kinesins/chemistry , Models, Molecular , Microtubules/metabolism , Biological Transport/physiology , Chlorocebus aethiops , COS Cells , Dimerization , Fluorescence Resonance Energy Transfer , Kinetics , Microscopy, Fluorescence
4.
European J Med Plants ; 2014 Dec; 4(12): 1420-1430
Article in English | IMSEAR | ID: sea-164208

ABSTRACT

The Natural Rubber Latex (NRL) from Hevea brasiliensis has shown promise in biomedical applications due to its low cost, easy handling, mechanical properties and biocompatibility, being used for bone regeneration and wound healing due to its natural stimulus to angiogenesis. The aim of this work was to incorporate Casearia sylvestris Sw. extract in NRL biomembranes and study its release behavior. The complex membraneextract has as object of study a new approach of using C. sylvestris extract in the treatment of wounds, for possessing antiseptic activity, anti-inflammatory and analgesic properties. The C. sylvestris species (Salicaceae), popularly known as "guaçatonga", presents great distribution and is used in folk medicine as antiulcer, wound healing, anti- snake venom, properties which have been proven and related to clerodane diterpenes (casearins A-X). The release rate of C. sylvestris compounds from extract-membrane complex was monitored and analyzed using the method of optical spectroscopy (UV-VIS). The release varied with temperature ranging from 14 to 33 days, releasing more than 90%, with an interesting and promising biomedical application, such as wound healing and burns.


Subject(s)
Biological Transport/physiology , Casearia/classification , Casearia/physiology , Drug Carriers/chemistry , Drug Delivery Systems , Hevea/classification , Hevea/physiology , Plant Extracts/isolation & purification , Plant Extracts/therapeutic use , Rubber , Wounds and Injuries/drug therapy
5.
Medicina (B.Aires) ; 74(2): 133-139, abr. 2014. ilus, graf
Article in Spanish | LILACS | ID: lil-708596

ABSTRACT

La fibrosis quística se debe a la ausencia o defecto del canal transmembrana regulador de la fibrosis quística (CFTR), un canal de cloruro codificado en el gen cftr que juega un papel clave en la homeostasis del agua e iones. El CFTR es activado por el AMPc y se localiza en las membranas apicales y basolaterales de las vías aéreas, intestino y glándulas exocrinas. Una de sus funciones primarias en los pulmones es mantener la capa de líquido superficial a través de su función de canal y regular el canal epitelial de sodio sensible al amiloride (ENaC). Se han identificado más de 1900 mutaciones en el gen cftr. La enfermedad se caracteriza por secreciones viscosas en las glándulas exocrinas y por niveles elevados de cloruro de sodio en el sudor. En la fibrosis quística el CFTR no funciona y el ENaC está desregulado; el resultado es un aumento en la reabsorción de sodio y agua con la formación de un líquido viscoso. En las glándulas sudoríparas tanto el Na+ como el Cl- se retienen en el lumen causando una pérdida de electrolitos durante la sudoración y el NaCl se elimina al sudor. Así, los niveles elevados de NaCl son la base del test del sudor inducido por pilocarpina, un método de diagnóstico para la enfermedad. En esta revisión se discuten los movimientos de Cl- y Na+ en las glándulas sudoríparas y pulmón así como el papel del ENaC en la patogénesis de la enfermedad.


Cystic fibrosis is caused by dysfunction or lack of the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel that has a key role in maintaining ion and water homoeostasis in different tissues. CFTR is a cyclic AMP-activated Cl- channel found in the apical and basal plasma membrane of airway, intestinal, and exocrine epithelial cells. One of CFTR’s primary roles in the lungs is to maintain homoeostasis of the airway surface liquid layer through its function as a chloride channel and its regulation of the epithelial sodium channel ENaC. More than 1900 CFTR mutations have been identified in the cftr gene. The disease is characterized by viscous secretions of the exocrine glands in multiple organs and elevated levels of sweat sodium chloride. In cystic fibrosis, salt and fluid absorption is prevented by the loss of CFTR and ENaC is not appropriately regulated, resulting in increased fluid and sodium resorption from the airways and formation of a contracted viscous surface liquid layer. In the sweat glands both Na+ and Cl- ions are retained in the lumen, causing significant loss of electrolytes during sweating. Thus, elevated sweat NaCl concentration is the basis of the classic pilocarpine-induced sweat test as a diagnostic feature of the disease. Here we discuss the ion movement of Cl- and Na+ ions in two tissues, sweat glands and in the air surface as well as the role of ENaC in the pathogenesis of cystic fibrosis.


Subject(s)
Humans , Biological Transport/physiology , Cell Membrane Permeability/physiology , Cystic Fibrosis Transmembrane Conductance Regulator/physiology , Cystic Fibrosis/physiopathology , Epithelial Sodium Channels/physiology
6.
Indian J Biochem Biophys ; 2011 Feb; 48(1): 7-13
Article in English | IMSEAR | ID: sea-135294

ABSTRACT

ATP-binding cassette (ABC) transporters utilize the energy present in cellular ATP to drive the translocation of structurally diverse set of solutes across the membrane barriers of eubacteria, archaebacteria and eukaryotes. In bacteria, these transporters are considered to be important virulence factors because they play role in nutrient uptake and in the secretion of toxins. The advances in structural determination and functional analysis of bacterial transporters have greatly increased our understanding of the mechanism of transport of these ABC transporters. Although progress in the field of structural biology has been made with the prokaryotic family members, it is likely that eukaryotic transporters will utilize the same mechanisms for translocation process. In this review, we summarize the function of the known MsbA ABC transporters in E. coli and mechanistic insights from structural and possible flippase mechanism studies.


Subject(s)
ATP-Binding Cassette Transporters/chemistry , ATP-Binding Cassette Transporters/metabolism , Adenosine Triphosphate/chemistry , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Biological Transport/physiology , Dimerization , Escherichia coli/metabolism , Hydrolysis , Membrane Transport Proteins/chemistry , Membrane Transport Proteins/metabolism , Phospholipid Transfer Proteins/chemistry , Phospholipid Transfer Proteins/metabolism , Protein Structure, Secondary , Protein Structure, Tertiary
7.
Biol. Res ; 44(1): 89-105, 2011. ilus, tab
Article in English | LILACS | ID: lil-591869

ABSTRACT

Since the discovery of the low-density lipoprotein receptor (LDLR) and its association with familial hypercholesterolemia in the early 1980s, a family of structurally related proteins has been discovered that has apolipoprotein E as a common ligand, and the broad functions of its members have been described. LRP2, or megalin, is a member of the LDLR family and was initially called gp330. Megalin is an endocytic receptor expressed on the apical surface of several epithelial cells that internalizes a variety of ligands including nutrients, hormones and their carrier proteins, signaling molecules, morphogens, and extracellular matrix proteins. Once internalized, these ligands are directed to the lysosomal degradation pathway or transported by transcytosis from one side of the cell to the opposite membrane. The availability of megalin at the cell surface is controlled by several regulatory mechanisms, including the phosphorylation of its cytoplasmic domain by GSK3, the proteolysis of the extracellular domain at the cell surface (shedding), the subsequent intramembrane proteolysis of the transmembrane domain by the gamma-secretase complex, and exosome secretion. Based on the important roles of its ligands and its tissue expression pattern, megalin has been recognized as an important component of many pathological conditions, including diabetic nephropathy, Lowe syndrome, Dent disease, Alzheimer's disease (AD) and gallstone disease. In addition, the expression of megalin and some of its ligands in the central and peripheral nervous system suggests a role for this receptor in neural regeneration processes. Despite its obvious importance, the regulation of megalin expression is poorly understood. In this review, we describe the functions of megalin and its association with certain pathological conditions as well as the current understanding of the mechanisms that underlie the control of megalin expression.


Subject(s)
Humans , Alzheimer Disease/metabolism , /physiology , Alzheimer Disease/physiopathology , Biological Transport/physiology , Cholesterol/physiology , Gallstones/metabolism , Gallstones/physiopathology , Gene Expression Regulation/physiology , Homeostasis/physiology , Kidney Diseases/metabolism , Kidney Diseases/physiopathology , /genetics , /metabolism , Tissue Distribution/physiology
8.
Arq. bras. endocrinol. metab ; 53(1): 95-101, fev. 2009. tab
Article in Portuguese | LILACS | ID: lil-509871

ABSTRACT

INTRODUÇÃO: Os portadores de diabetes melito tipo 1 (DM1) possuem aumentado risco de doença cardiovascular e, ainda assim, podem apresentar perfil lipídico normal. Para esclarecer se os níveis normais de HDL podem ocultar defeitos na função, foram estudados a transferência de lípides para a HDL em DM1. MÉTODOS: Vinte e uma mulheres jovens portadoras de DM1 foram comparadas com 21 mulheres não-diabéticas. Nanoemulsões foram usadas como doadoras de lípides para HDL: uma marcada com ³H-triglicérides e 14C-colesterol livre e outra com ³H-éster de colesterol e 14C-fosfolípides. Após 1 hora de incubação com amostras de plasma, seguida por precipitação química, o sobrenadante, contendo HDL, teve a radioatividade contada. RESULTADOS: Nenhuma diferença foi encontrada nas transferências dos ésteres de colesterol, triglicérides, colesterol livre e fosfolípides para as HDL. CONCLUSÃO: A transferência de lípides para a HDL não está afetada em portadoras de DM1. Isso sugere que a doença não altera a composição de lipoproteínas e a ação de proteínas de transferência.


INTRODUCTION: People with type 1 diabetes mellitus (T1DM) have an increased risk of cardiovascular disease and may still have a normal lipid profile. In order to clarify whether normal HDL cholesterol levels may conceal defects in HDL function, we have studied the transfer of lipids to HDL in T1DM. METHODS: Twenty-one young women with T1DM were compared with 21 non-diabetic women. Nanoemulsion preparations were used as lipid donor to HDL: one labeled with ³H-triglycerides and 14C-free cholesterol and the other with ³H-cholesteryl esters and 14C-phospholipids. These preparations were incubated with plasma samples for 1h. After chemical precipitation, the supernatant containing HDL was counted for radioactivity. RESULTS: No difference in transfer was observed to nanoemulsion HDL from cholesteryl esters, triglycerides, free cholesterol and phospholipids. CONCLUSION: Simultaneous lipid transfer to HDL was not affected in T1DM patients. This suggests that the disease does not alter lipoprotein composition and transfer protein action in such way as to disturb HDL metabolism.


Subject(s)
Adult , Female , Humans , Young Adult , Carrier Proteins/metabolism , Diabetes Mellitus, Type 1/metabolism , Lipids/administration & dosage , Lipoproteins, HDL/ultrastructure , Nanoparticles/administration & dosage , Biological Transport/physiology , Case-Control Studies , Cholesterol Esters/administration & dosage , Cholesterol Esters/blood , Cholesterol Esters/pharmacokinetics , Lipids/blood , Lipids/pharmacokinetics , Lipoproteins, HDL/chemistry , Lipoproteins, HDL/metabolism , Phospholipids/administration & dosage , Phospholipids/blood , Phospholipids/pharmacokinetics , Statistics, Nonparametric , Triglycerides/administration & dosage , Triglycerides/blood , Triglycerides/pharmacokinetics , Young Adult
9.
Medicina (B.Aires) ; 67(1): 71-81, jan.-fev. 2007. ilus, graf, tab
Article in Spanish | LILACS | ID: lil-464750

ABSTRACT

La altura, fascinante laboratorio natural de investigación médica, provee resultados con importantes implicancias para la comprensión de enfermedades que afectan a millones de personas que viven en ella, asi como para el tratamiento de enfermedades ligadas a la hipoxemia en pacientes que viven en baja altitud. El edema pulmonar de altura (EPA) es una entidad que pone en peligro la vida y que ocurre en sujetos predispuestos pero sanos. Esto permite estudiar los mecanismos subyacentes del edema pulmonar en humanos, sin la presencia de factores que presten a la confusión como enfermedades concomitantes. El EPA resulta de la conjunción de dos defectos mayores: acumulación de líquido en el espacio alveolar debido a una hipertensión pulmonar hipóxica exagerada, y alteración en la eliminación del mismo por un defecto en el transporte transepitelial alveolar de sodio. En esta revisión, describimos brevemente las características clínicas y revisaremos este novedoso concepto. Proveemos evidencia experimental de como la síntesis alterada de óxido nítrico y/o la disminución de su biodisponibilidad representan el defecto central que predispone a la vasoconstricción pulmonar hipóxica exagerada y a la acumulación de líquido en el espacio alveolar. Mostramos que la hipertensión pulmonar hipóxica exagerada, per se, no es suficiente para producir un EPA, y que una alteración en la eliminación del fluido del espacio alveolar representa un segundo mecanismo fisiopatológico importante. Finalmente, describimos cómo los nuevos aportes obtenidos de los estudios del EPA pueden ser trasladados al manejo de otros estados patológicos ligados a la hipoxemia.


High altitude constitutes an exciting natural laboratory for medical research. Over the past decade, it has become clear that the results of high-altitude research may have important implications not only for the understanding of diseases in the millions of people living permanently at high altitude, but also for the treatment of hypoxemia-related disease states in patients living at low altitude. High-altitude pulmonary edema (HAPE) is a life-threatening condition occurring in predisposed, but otherwise healthy subjects, and, therefore, allows to study underlying mechanisms of pulmonary edema in humans, in the absence of confounding factors. Over the past decade, evidence has accumulated that HAPE results from the conjunction of two major defects, augmented alveolar fluid flooding resulting from exaggerated hypoxic pulmonary hypertension, and impaired alveolar fluid clearance related to defective respiratory transepithelial sodium transport. Here, after a brief presentation of the clinical features of HAPE, we review this novel concept. We provide experimental evidence for the novel concept that impaired pulmonary endothelial and epithelial nitric oxide synthesis and/or bioavailability may represent the central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and alveolar fluid flooding. We demonstrate that exaggerated pulmonary hypertension, while possibly a condition sine qua non, may not be sufficient to cause HAPE, and how defective alveolar fluid clearance may represent a second important pathogenic mechanism. Finally, we outline how this insight gained from studies in HAPE may be translated into the management of hypoxemia related disease states in general.


Subject(s)
Humans , Altitude Sickness/physiopathology , Hypertension, Pulmonary/complications , Pulmonary Circulation , Pulmonary Edema/etiology , Sympathetic Nervous System , Altitude Sickness/complications , Altitude Sickness/drug therapy , Biological Availability , Biological Transport/physiology , Blood Pressure/drug effects , Blood Pressure/physiology , Epithelial Sodium Channels/physiology , Hypertension, Pulmonary/drug therapy , Hypertension, Pulmonary/physiopathology , Nitric Oxide/biosynthesis , Nitric Oxide/pharmacokinetics , Pulmonary Alveoli/drug effects , Pulmonary Circulation/physiology , Pulmonary Edema/drug therapy , Pulmonary Edema/physiopathology , Sodium/pharmacokinetics , Sodium/therapeutic use , Sympathetic Nervous System/physiopathology
10.
An. acad. bras. ciênc ; 78(2): 255-269, June 2006. ilus, tab
Article in English | LILACS | ID: lil-427103

ABSTRACT

As membranas plasmáticas das células intestinais dos insetos apresentam um domínio apical e outro basal. O domínio apical é geralmente modificado em microvilosidades com organização molecular similar a de outros animais, embora possam diferir naqueles insetos que apresentam vesículas secretoras em trânsito que brotam lateralmente ou destacam-se das extremidades das microvilosidades. Outras modificações microvilares estão associadas a bombeamento de prótons ou a interrelações com uma membrana lipídica (a membrana perimicrovilar) que reveste as microvilosidades de células intestinais de hemípteros (pulgões e percevejos). Admite-se que as membranas perimicrovilares estejam envolvidas na absorção de aminoácidos a partir de dietas diluídas. As membranas microvilares e perimicrovilares tem densidades distintas (e conteúdo protéico) que dependem do táxon do inseto. O papel desempenhado pelas proteínas microvilares e perimicrovilares na fisiologia intestinal dos insetos é revisto, procurando fornecer uma visão coerente dos dados e chamando a atenção para novos objetivos de pesquisa.


Subject(s)
Animals , Cell Membrane/ultrastructure , Digestive System/ultrastructure , Insecta/ultrastructure , Biological Transport/physiology , Cell Membrane/physiology , Digestive System/metabolism , Insecta/physiology , Microvilli/physiology , Microvilli/ultrastructure , Phylogeny
11.
Biol. Res ; 37(4): 653-660, 2004. ilus
Article in English | LILACS | ID: lil-437522

ABSTRACT

Although it has long been known that mitochondria possess a complex molecular repertoire for accumulating and releasing Ca2+, only in recent years has a large body of data demonstrated that these organelles promptly respond to Ca2+-mediated cell stimulations. In this contribution, we will review the principles of mitochondrial Ca2+ homeostasis and its signaling role in different physiological and pathological conditions.


Subject(s)
Humans , Apoptosis/physiology , Calcium/physiology , Calcium/metabolism , Calcium Channels/physiology , Calcium Channels/metabolism , Homeostasis/physiology , Calcium Signaling/physiology , Biological Transport/physiology
12.
West Indian med. j ; 52(4): 267-272, Dec. 2003.
Article in English | LILACS | ID: lil-410700

ABSTRACT

The projections of vagal brainstem neurons to the duodenal segment of the gastrointestinal tract were studied in the ferret using the WGA-HRP neurohistochemical technique. Fourteen adult ferrets with weights ranging from 800 gm to 1500 gm were used for the study. The muscular wall of the duodenum of six ferrets was injected with 0.1 ml of 5 WGA-HRP in 0.5 M sodium chloride. The eight remaining ferrets were used as controls. Two of these had injections of 0.1 ml normal saline into the muscular wall of the duodenum. The second set of two ferrets was injected with 0.1 ml of 5 WGA-HRP in buffer after bilateral truncal vagotomy. The third set of two ferrets received intraperitoneal injection of 0.1 ml of 5 WGA-HRP while, in the last set, the tracer was injected into the hepatic portal vein. Following the injections, the ferrets were allowed to survive for 48-72 hours after which each ferret was perfused transcardially first with normal saline followed by a fixative containing 1 paraformaldehyde and 1.25 glutaraldehyde in 0.1 M phosphate buffer, pH 7.4 at room temperature and finally with 10 buffered sucrose at 4 degrees C. Transverse serial frozen sections of the brainstem were then taken and processed for WGA-HRP neurohistochemistry and were analyzed under light and dark-field illuminations. The analyses of the sections taken from the six ferrets injected with WGA-HRP revealed neurons labelled with the tracer in the dorsal motor nucleus of the vagus nerve (DMNV). Sections taken from the control ferrets did not reveal any WGA-HRP labelled neurons in the brainstem


Subject(s)
Animals , Male , Female , Duodenum/drug effects , Duodenum/innervation , Autonomic Fibers, Preganglionic/drug effects , Autonomic Fibers, Preganglionic/physiology , Neurons/drug effects , Neurons/physiology , Parasympathetic Nervous System/drug effects , Parasympathetic Nervous System/physiology , Molecular Probes/pharmacology , Models, Animal , Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate , Vagus Nerve/drug effects , Vagus Nerve/physiology , Molecular Probes/pharmacokinetics , Biological Transport/physiology , Neural Pathways/physiology
13.
Article in English | IMSEAR | ID: sea-41857

ABSTRACT

Renal cortical brush-border (BBM), basolateral membrane (BLM), and medullary plasma membrane (mPM) preparations were analyzed to assess the effects of life-long food restriction in aged rats on membrane lipid content. Young male Fischer 344 x Brown-Norway F1 rats consumed food ad libitum (young AL) or were food-restricted (FR, 60% of AL consumption) for either 6 weeks (young FR) or until the age of 30 months old (old FR). Senescent FR rats had 50 per cent decreases in fractional excretion of Na and K (p < 0.001) as compared with the young AL rats. Long-term FR reduced phosphate and titratable acid excretion by 80 per cent (p < 0.001). These values were not significantly different from those observed in young rats during 6 weeks of FR. Food restriction decreased renal Na, K-ATPase activity by 50 per cent (p < 0.001) in both old and young FR animals. Reduction of food intake, in old and young rats, decreased all BBM phospholipid concentrations (phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin) by 50 per cent than in the AL rats (p < 0.001). In BLM, chronic FR resulted only in lower phosphatidylcholine concentration (by 21%, p < 0.05) while phosphatidylethanolamine was increased approximately 80 per cent (p < 0.001). Total phospholipid content in mPM was progressively decreased by 23 per cent (p < 0.05) in the young FR group to be 55 per cent (p < 0.001) in the old FR rats. Cholesterol content was reduced in BBM and mPM by 38 per cent and 25 per cent (p < 0.05), respectively, during long-term FR. Both total phospholipid and cholesterol contents detected in mPM of the old FR rats were significantly lower than those obtained from the young FR animals (by 42%, p < 0.001 and 12%, p < 0.05, respectively). Plasma glucose, blood urea nitrogen, and body weight maintained at significantly lower levels during chronic FR. That life-long FR could prevent renal membrane lipid deposition and could lower renal work may explain the mechanisms that FR can delay the onset and diminish the severity of age-associated renal diseases.


Subject(s)
Aging/physiology , Animals , Basement Membrane/metabolism , Biological Transport/physiology , Diet , Food Deprivation , Kidney Cortex/metabolism , Kidney Diseases/prevention & control , Kidney Function Tests , Lipid Metabolism , Male , Microvilli , Models, Animal , Phospholipids/analysis , Rats , Rats, Inbred F344 , Reference Values , Sodium-Potassium-Exchanging ATPase/analysis , Time Factors
14.
Biol. Res ; 33(3/4): 209-214, 2000.
Article in English | LILACS | ID: lil-454064

ABSTRACT

Gray gulls, Larus modestus, nest 1500 m above sea level in northern Chile's Atacama Desert, one of the driest in the world. Their eggshell gas permeability, one third of that found in other Larus species, is an adaptation that reduces water loss, but at the expense of oxygen diffusion into the air cell with resultant hypoxia and reduced metabolic rate. This contrasts with characteristics found in birds nesting at very high altitudes where oxygen diffusion across the egg shell is maximized at the expense of water conservation. The oxygen consumption (MO2) of Larus modestus is 66% that of Larus argentatus; the oxygen conductance (GO2) is equivalent to 48% of that obtained in 5 other bird species. The oxygen partial pressure (PAO2) in the air chamber of Larus modestus (84 Torr) is lower than that of 10 other bird species whose average (PAO2) is 106 Torr. The CO2 partial pressure (PACO2) in the air chamber of Larus modestus is 68 Torr, a higher value than that found in 9 other bird species whose average (PACO2) is 39 Torr.


Subject(s)
Animals , Adaptation, Physiological/physiology , Water/metabolism , Charadriiformes , Egg Shell/metabolism , Oxygen Consumption/physiology , Oxygen/metabolism , Chile , Desert Climate , Diffusion , Permeability , Biological Transport/physiology
15.
Biol. Res ; 33(2): 133-142, 2000. ilus, graf
Article in English | LILACS | ID: lil-443669

ABSTRACT

Cells tightly regulate iron levels through the activity of iron regulatory proteins (IRPs) that bind to RNA motifs called iron responsive elements (IREs). When cells become iron-depleted, IRPs bind to IREs present in the mRNAs of ferritin and the transferrin receptor, resulting in diminished translation of the ferritin mRNA and increased translation of the transferrin receptor mRNA. Similarly, body iron homeostasis is maintained through the control of intestinal iron absorption. Intestinal epithelia cells sense body iron through the basolateral endocytosis of plasma transferrin. Transferrin endocytosis results in enterocytes whose iron content will depend on the iron saturation of plasma transferrin. Cell iron levels, in turn, inversely correlate with intestinal iron absorption. In this study, we examined the relationship between the regulation of intestinal iron absorption and the regulation of intracellular iron levels by Caco-2 cells. We asserted that IRP activity closely correlates with apical iron uptake and transepithelial iron transport. Moreover, overexpression of IRE resulted in a very low labile or reactive iron pool and increased apical to basolateral iron flux. These results show that iron absorption is primarily regulated by the size of the labile iron pool, which in turn is regulated by the IRE/IRP system.


Subject(s)
Humans , Intestinal Absorption/physiology , Ferritins , Iron/metabolism , Iron-Regulatory Proteins/metabolism , Receptors, Transferrin/metabolism , Homeostasis/physiology , Intracellular Membranes/metabolism , Intestinal Mucosa/cytology , Intestinal Mucosa/metabolism , RNA, Messenger/metabolism , Biological Transport/physiology
18.
Journal of Korean Medical Science ; : 123-132, 2000.
Article in English | WPRIM | ID: wpr-18582

ABSTRACT

The vectorial transepithelial transport of water and electrolytes in the renal epithelium is achieved by the polarized distribution of various transport proteins in the apical and basolateral membrane. The short-term regulation of transepithelial transport has been traditionally thought to be mediated by kinetic alterations of transporter without changing the number of transporters. However, a growing body of recent evidence supports the possibility that the stimulus-dependent recycling of transporter-carrying vesicles can alter the abundance of transporters in the plasma membrane in parallel changes in transepithelial transport functions. The abundance of transporters in the plasma membrane is determined by net balance between stimulus-dependent exocytic insertion of transporters into and endocytic retrieval of them from the plasma membrane. The vesicular recycling occurs along the tracts of the actin microfilaments and microtubules with associated motors. This review is to highlight the importance of vesicular transport in the short-term regulatory process of transepithelial transport in the renal epithelium. In the short-term regulation of many other renal transporters, vesicular transport is likely to be also involved. Thus, vesicular transport is now emerged as a wide-spread general regulatory mechanism involved in short-term regulation of renal functions.


Subject(s)
Humans , Animals , Biological Transport/physiology , Endocytosis/physiology , Epithelial Cells/enzymology , Epithelial Cells/cytology , Exocytosis , Proton-Translocating ATPases/metabolism , Sodium Channels/metabolism
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