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1.
J Prev Alzheimers Dis ; 9(4): 601-616, 2022.
Article in English | MEDLINE | ID: mdl-36281664

ABSTRACT

OBJECTIVE: A systematic review of randomized controlled trials was conducted to determine the effect of physical exercise on physical-functional capacity, cognitive performance, neuropsychiatric symptoms, and quality of life in a population of older people with Alzheimer´s disease. DATA SOURCES: Pubmed, Scopus, PEDro, Web of Science, CINAHL, Cochrane Library, grey literature and a reverse search from inception to April 2021 were searched to identify documents. STUDY SELECTION: Publications investigating the effect of any type of physical exercise-based intervention in any of its multiple modalities on physical-functional capacity, cognitive performance, neuropsychiatric symptoms, and quality of life were searched. DATA EXTRACTION: The data were extracted into predesigned data extraction tables. Risk of bias was evaluated through the PEDro scale and its internal validity scale. DATA SYNTHESIS: A total of 8 different randomized controlled trials with a total sample of 562 non-overlap Alzheimer disease patients between 50-90 years and a mean age of 75.2 ± 3.9 years were eligible for analyses. Physical-functional capacity was evaluated in 6 of 8 studies and cognitive performance was evaluated in 5 of 8 studies, all of them showed improvements in these variables when compared with the controls, except for two studies in physical-functional capacity and one study for cognitive performance. In the physical-functional capacity and cognitive performance variables, aerobic physical exercise was used in isolation, or in a multimodal way, combining aerobic, strength and balance exercise, from 2 to 7 weekly sessions with doses between 30 and 90 minutes, and a duration of the program comprised of 9 weeks to 6 months. Neuropsychiatric symptoms and quality of life were evaluated in 2 of 8 studies, which the intervention groups experienced significant improvements when compared with the control groups, except for one study that found similar differences in quality of life between both groups. In the neuropsychiatric symptoms and quality of life variables, only aerobic physical exercise was used, in a more homogeneous way, from 2 to 3 weekly sessions with doses of 30 to 60 minutes, and a total program duration of 9 to 16 weeks. CONCLUSIONS: Despite the scarcity of studies, especially those based on multimodal proposals, and the heterogeneity in the protocols, this systematic review found moderate to limited evidence that aerobic physical exercise on its own or combined in a multimodal program that also includes strength and balance exercise can be a useful tool in the management of patients with Alzheimer's disease with the aim of maintaining and/or improving physical-functional capacity and cognitive performance. In addition, this review found moderate evidence of the positive impact that aerobic physical exercise could have in reducing neuropsychiatric symptoms and improving quality of life in patients with Alzheimer´s disease. PROSPERO registration number: CRD42021229891.


Subject(s)
Alzheimer Disease , Exercise Therapy , Exercise , Aged , Aged, 80 and over , Humans , Middle Aged , Alzheimer Disease/physiopathology , Alzheimer Disease/therapy , Exercise/physiology , Quality of Life , Randomized Controlled Trials as Topic , Treatment Outcome
2.
Pflugers Arch ; 458(1): 39-52, 2009 May.
Article in English | MEDLINE | ID: mdl-18758808

ABSTRACT

Homeostasis of inorganic phosphate (P(i)) is primarily an affair of the kidneys. Reabsorption of the bulk of filtered P(i) occurs along the renal proximal tubule and is initiated by apically localized Na(+)-dependent P(i) cotransporters. Tubular P(i) reabsorption and therefore renal excretion of P(i) is controlled by a number of hormones, including phosphatonins, and metabolic factors. In most cases, regulation of P(i) reabsorption is achieved by changing the apical abundance of Na(+)/Pi cotransporters. The regulatory mechanisms involve various signaling pathways and a number of proteins that interact with Na(+)/P(i) cotransporters.


Subject(s)
Kidney Tubules, Proximal/metabolism , Phosphates/metabolism , Sodium-Phosphate Cotransporter Proteins/physiology , Acidosis/physiopathology , Animals , Cholecalciferol/physiology , Circadian Rhythm , Diet , Fibroblast Growth Factor-23 , Fibroblast Growth Factors/physiology , Gene Expression Regulation , Glucuronidase/physiology , Gonadal Steroid Hormones/physiology , Homeostasis , Humans , Ion Transport , Klotho Proteins , Parathyroid Hormone/physiology , Phosphates/urine , Phosphoproteins/physiology , Potassium Deficiency/physiopathology , Signal Transduction , Sodium-Hydrogen Exchangers/physiology , Sodium-Phosphate Cotransporter Proteins, Type IIa/physiology , Sodium-Phosphate Cotransporter Proteins, Type IIc/physiology
3.
An. psiquiatr ; 22(6): 296-305, nov. 2006. ilus
Article in Es | IBECS | ID: ibc-051898

ABSTRACT

Introducción: El impacto de un primer episodio psicótico tienes unas consecuencias que van mucho más allá de los aspectos sintomáticos. Este irrumpe en la vida de la persona paralizando prácticamente todas las esferas que la configuran; el rol profesional, la formación, la espera familiar, social y la relación de pareja. Objetivo: Describir los mecanismos de autocompresión de la enfermedad, repercusión subjetiva y proceso de afrontamiento de una persona a partir de un primer episodio psicótico con evolución posterior a un trastorno esquizofrénico. Resultados: Se destaca la presencia de tres etapas diferentes de duela en la esquizofrenia que tienen características de la conciencia de pérdida o la forma ambigua de las pérdidas. Conclusiones: Podemos hablar de la presencia de un proceso de duelos múltiples durante la fase inicial de la esquizofrenia que tiene consecuencias terapéuticas directas a tener presentes durante la intervención


Introduction: The impact of first episode psychosis could be traumatic indepently of the severity of the symptoms. In this sense, the life of persons who have a first episode psychosis could be paralysed in different areas: their professional role, careers, family, social relations and the affective relationships. Objective: To describe the patients mechanism used to be aware of the illness, subjective impact and coping process of a patient who had a first episode schizophrenia. Results: We observed three different grief stages in the initial phase of schizophrenia with distinctive characteristics as another grief process. Theses differences are the sequence of the awareness of things they lost and the ambiguity of the them. Conclusions: We can confirm the presence os a multiple grief process during the initial phase of schizophrenia. The data supports the idea that we have to aware that there are some therapeutic implications in the intervention with schizophrenic patients who are in the initial phase of the illness


Subject(s)
Male , Adult , Humans , Psychotic Disorders/diagnosis , Psychotic Disorders/epidemiology , Grief , Affective Disorders, Psychotic/complications , Affective Disorders, Psychotic/diagnosis , Schizophrenic Psychology , Psychotherapy/methods , Psychotherapy/standards , Adaptation, Psychological/physiology , Adjustment Disorders/psychology , Affective Disorders, Psychotic/epidemiology , Schizophrenia/complications , Psychotic Disorders/complications , Schizophrenia/diagnosis , Ego , Gender Identity , Identity Crisis
4.
Kidney Int ; 70(10): 1725-34, 2006 Nov.
Article in English | MEDLINE | ID: mdl-17003823

ABSTRACT

Renal Fanconi syndrome occurs in about 1-5% of all children treated with Ifosfamide (Ifo) and impairment of renal phosphate reabsorption in about 20-30% of them. Pathophysiological mechanisms of Ifo-induced nephropathy are ill defined. The aim has been to investigate whether Ifo metabolites affect the type IIa sodium-dependent phosphate transporter (NaPi-IIa) in viable opossum kidney cells. Ifo did not influence viability of cells or NaPi-IIa-mediated transport up to 1 mM/24 h. Incubation of confluent cells with chloroacetaldehyde (CAA) and 4-hydroperoxyIfosfamide (4-OH-Ifo) led to cell death by necrosis in a concentration-dependent manner. At low concentrations (50-100 microM/24 h), cell viability was normal but apical phosphate transport, NaPi-IIa protein, and -mRNA expression were significantly reduced. Coincubation with sodium-2-mercaptoethanesulfonate (MESNA) prevented the inhibitory action of CAA but not of 4-OH-Ifo; DiMESNA had no effect. Incubation with Ifosfamide-mustard (Ifo-mustard) did alter cell viability at concentrations above 500 microM/24 h. At lower concentrations (50-100 microM/24 h), it led to significant reduction in phosphate transport, NaPi-IIa protein, and mRNA expression. MESNA did not block these effects. The effect of Ifo-mustard was due to internalization of NaPi-IIa. Cyclophosphamide-mustard (CyP-mustard) did not have any influence on cell survival up to 1000 microM, but the inhibitory effect on phosphate transport and on NaPi-IIa protein was the same as found after Ifo-mustard. In conclusion, CAA, 4-OH-Ifo, and Ifo- and CyP-mustard are able to inhibit sodium-dependent phosphate cotransport in viable opossum kidney cells. The Ifo-mustard effect took place via internalization and reduction of de novo synthesis of NaPi-IIa. Therefore, it is possible that Ifo-mustard plays an important role in pathogenesis of Ifo-induced nephropathy.


Subject(s)
Acetaldehyde/analogs & derivatives , Ifosfamide/analogs & derivatives , Ifosfamide/pharmacology , Phosphates/metabolism , Phosphoramide Mustards/pharmacology , Sodium-Phosphate Cotransporter Proteins, Type IIa/drug effects , Sodium-Phosphate Cotransporter Proteins, Type IIa/metabolism , Acetaldehyde/pharmacology , Animals , Antineoplastic Agents, Alkylating , Biological Transport/drug effects , Cell Death/drug effects , Cell Line , Dose-Response Relationship, Drug , Gene Expression Regulation/drug effects , Gene Expression Regulation/genetics , Ifosfamide/metabolism , Kidney/cytology , Kidney/drug effects , Kidney/metabolism , Mesna/pharmacology , Opossums , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sodium-Phosphate Cotransporter Proteins, Type IIa/genetics
5.
Kidney Int ; 70(9): 1548-59, 2006 Nov.
Article in English | MEDLINE | ID: mdl-16955105

ABSTRACT

Members of the SLC34 gene family of solute carriers encode for three Na+-dependent phosphate (P i) cotransporter proteins, two of which (NaPi-IIa/SLC34A1 and NaPi-IIc/SLC34A3) control renal reabsorption of P i in the proximal tubule of mammals, whereas NaPi-IIb/SCLC34A2 mediates P i transport in organs other than the kidney. The P i transport mechanism has been extensively studied in heterologous expression systems and structure-function studies have begun to reveal the intricacies of the transport cycle at the molecular level using techniques such as cysteine scanning mutagenesis, and voltage clamp fluorometry. Moreover, sequence differences between the three types of cotransporters have been exploited to obtain information about the molecular determinants of hormonal sensitivity and electrogenicity. Renal handling of P i is regulated by hormonal and non-hormonal factors. Changes in urinary excretion of P i are almost invariably mirrored by changes in the apical expression of NaPi-IIa and NaPi-IIc in proximal tubules. Therefore, understanding the mechanisms that control the apical expression of NaPi-IIa and NaPi-IIc as well as their functional properties is critical to understanding how an organism achieves P i homeostasis.


Subject(s)
Kidney Tubules, Proximal/metabolism , Phosphates/metabolism , Sodium-Phosphate Cotransporter Proteins, Type IIa/metabolism , Sodium-Phosphate Cotransporter Proteins, Type IIb/metabolism , Sodium-Phosphate Cotransporter Proteins, Type IIc/metabolism , Animals , Homeostasis , Humans , Mice , Parathyroid Hormone/physiology , Sodium-Phosphate Cotransporter Proteins, Type IIa/chemistry , Sodium-Phosphate Cotransporter Proteins, Type IIa/genetics , Sodium-Phosphate Cotransporter Proteins, Type IIb/chemistry , Sodium-Phosphate Cotransporter Proteins, Type IIb/genetics , Sodium-Phosphate Cotransporter Proteins, Type IIc/chemistry , Sodium-Phosphate Cotransporter Proteins, Type IIc/genetics , Structure-Activity Relationship
7.
J Physiol ; 567(Pt 1): 21-6, 2005 Aug 15.
Article in English | MEDLINE | ID: mdl-15890704

ABSTRACT

Regulation of renal proximal tubular reabsorption of phosphate (Pi) is one of the critical steps in Pi homeostasis. Experimental evidence suggests that this regulation is achieved mainly by controlling the apical expression of the Na+-dependent Pi cotransporter type IIa (NaPi-IIa) in proximal tubules. Only recently have we started to obtain information regarding the molecular mechanisms that control the apical expression of NaPi-IIa. The first critical observation was the finding that truncation of only its last three amino acid residues has a strong effect on apical expression. A second major finding was the observation that the last intracellular loop of NaPi-IIa contains sequence information that confers parathyroid hormone (PTH) sensitivity. The use of the above domains of the cotransporter in yeast two-hybrid (Y2H) screening allowed the identification of proteins interacting with NaPi-IIa. Biochemical and morphological, as well as functional, analyses have allowed us to obtain insights into the physiological roles of such interactions, although our present knowledge is still far from complete.


Subject(s)
Kidney Tubules, Proximal/metabolism , Phosphates/metabolism , Symporters/metabolism , Animals , Humans , Sodium/metabolism , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type IIa
8.
Psiquis (Madr.) ; 26(3): 109-120, 2005. tab
Article in Es | IBECS | ID: ibc-039516

ABSTRACT

La motivación del paciente ha sido considerada como un requisito previo de cualquier tratamiento o intervención psicoterapéutica sin el cual la efectividad de la misma se vería mermada. En los últimos años han sido muchos los trabajos que han centrado sus esfuerzos en el estudio de la motivación en el contexto de la práctica clínica. En la intervención de las personas que padecen esquizofrenia el trabajo sobre la motivación se hace imprescindible, dados los factores clínicos vinculados a la enfermedad. El presente trabajo revisa los estudios que presentan intervenciones motivacionales en pacientes que sufren esquizofrenia, además de aportar algunas consideraciones de la intervención motivacional en la esquizofrenia en la práctica clínica


Patient motivation has been considered as a previous requirement of any treatment or psychotherapy effectiveness. In the last years a lot of studies have worked hard about motivation in clinical practice context. In the intervention of the schizophrenic patients the work on the motivation is made essential, once the clinical factors linked to the illness have been given. The current study review the studies that present motivational interventions in patients who suffer schizophrenia, besides contributing some considerations of the motivational intervention in the illnes


Subject(s)
Humans , Schizophrenia/therapy , Motivation , Interview, Psychological/methods , Choice Behavior , Self Efficacy , Interpersonal Relations , Treatment Refusal/psychology
9.
Methods Find Exp Clin Pharmacol ; 25(7): 531-5, 2003 Sep.
Article in English | MEDLINE | ID: mdl-14571283

ABSTRACT

The aim of this study was to compare the main pharmacokinetic characteristics of two new paracetamol formulations, powder sachet and tablet, with that of three commercially available paracetamol formulations: two conventional solid tablets and one effervescent tablet. Twelve healthy volunteers participated in an open, single dose (paracetamol 1,000 mg), randomized, five-way, crossover study. Formulations studied included: formulation A: 2 x 500 mg paracetamol tablets (Laboratorios Belmac S.A.); formulation B: 1 x 1,000 mg paracetamol powder sachets (Laboratorios Belmac, S.A.); formulation C: 2 x 500 mg paracetamol film-coated tablets (Panadol, SmithKline Beecham); formulation D: 2 x 500 mg paracetamol tablets (Tylenol, McNeil); and formulation E: 1 x 1,000 mg effervescent paracetamol tablets (Efferalgan, UPSA). The primary variables were area under the plasma concentration time curve extrapolated to infinity (AUC(0-infinity)), maximum plasma concentration (Cmax), and time to maximum plasma concentration (tmax). Mean AUC(0-infinity) ranged from 52.6 (B) to 56.3 microg x h/ml (D); mean Cmax varied between 17.98 (C) and 20.73 microg/ml (E); mean tmax ranged from 0.40 (E) to 0.88 h (C); and median t(1/2) varied between 2.65 (C) and 2.81 h (A). Formulations A, B and E showed significantly shorter tmax than formulation C. The tmax and Cmax values found for formulations A and B were very similar to that found for E, an effervescent tablet formulation. In conclusion, the two new formulations of paracetamol tested in this study were absorbed rapidly after a single oral dose in healthy volunteers, similar to an effervescent paracetamol formulation and significantly faster than two ordinary commercialized paracetamol tablets.


Subject(s)
Acetaminophen/administration & dosage , Acetaminophen/pharmacokinetics , Analgesics, Non-Narcotic/administration & dosage , Analgesics, Non-Narcotic/pharmacokinetics , Acetaminophen/blood , Administration, Oral , Adult , Analgesics, Non-Narcotic/blood , Area Under Curve , Biological Availability , Cross-Over Studies , Female , Half-Life , Humans , Male , Powders , Tablets
10.
An. psiquiatr ; 19(4): 143-149, abr. 2003. tab, graf
Article in Spanish | IBECS | ID: ibc-126280

ABSTRACT

Objetivo: El objetivo de esta investigación es estudiar los niveles de ansiedad y su evolución en una población adolescente ingresada en dos unidades: hospital general (HG) y hospital de día (HD). Se ha realizado un diseño observacional, descriptivo y longitudinal en cuatro unidades hospitalarias: Hospital Sant Joan de Déu de Barcelona. Hospital de Día Orienta de Gavá. Hospital de Día Sant Joan de Déu de Barcelona y Mollet. Resultados: Existen diferencias entre los niveles de ansiedad de ambas unidades (HG x = 33,77; HD x = 23,94). Un 68,4% de pacientes presenta niveles importantes de ansiedad durante la hospitalización. Conclusiones: Los niveles de ansiedad son significativamente más intensos en el HG pero no existen diferencias significativas en su evolución temporal. Algunas variables como la procedencia y la insatisfacción con la familia están relacionadas con una ansiedad elevada (AU)


Objective: We try to study levels and their developement in teenagers who hospitalized in two hospital units: day care (DH) and 24 hours hospital (GH). It is an observation and longitudinal desing in the following units: Sant Joan de Déu Hospital from Barcelona, Orienta Outpatient Unit of Gavá, San Joan de Déu Outpatient Unit of Barcelona and Mollet. Results: There are diferences between anxiety levels of both hospitalary units (GH x = 33,77; DH: x = 23,94). A 68,4% of patients have importants levels of anxiety during hospitalization, and a 40,8% of them show the higher levels. Discussion: We have found remarkable diferences and temporal stability among the levels of anxiety patients in wards. This levels are higher in psychiatric hospital than day hospital, but the diferences aren’t significantly in temporal evolution. Residence and satisfaction with family relationship are related to this anxiety (AU)


Subject(s)
Humans , Male , Female , Child , Adolescent , Anxiety/psychology , Adolescent, Hospitalized/psychology , Mental Disorders/psychology , Interview, Psychological/methods , Adolescent Behavior/psychology , Family Relations , Day Care, Medical , Hospitals, General/statistics & numerical data , Psychiatric Department, Hospital/statistics & numerical data
11.
Pflugers Arch ; 443(2): 306-13, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11713658

ABSTRACT

Inhibition of proximal tubular phosphate (Pi) reabsorption involves, as far as we know, brush border membrane retrieval of the type IIa Na/Pi-cotransporter. The aim of the present study was to analyze whether intracellular cGMP-mediated regulation of Pi reabsorption also involves retrieval of the type IIa Na/Pi-cotransporter, as previously shown for cAMP. Atrial natriuretic peptide (ANP) and nitric oxide (NO) were used to stimulate guanylate cyclase. In vivo perfusion of mice kidneys with either ANP or NO donors resulted in a downregulation of type IIa Na/Pi-cotransporters on the brush border membranes of proximal tubules. These effects were mimicked by activation of protein kinase G with 8Br-cGMP. In in-vitro-perfused mice proximal tubules, ANP was effective when added either to the apical or basolateral perfusate, suggesting the presence of receptors on both membrane sites. The effects of ANP and NO were blocked by the protein kinase G inhibitor LY 83553. Parallel experiments in OK cells, a renal proximal tubule model, provided similar information. Our findings document that cGMP-mediated regulation (ANP and NO) of type IIa Na/Pi-cotransporters also takes place via internalization of the transporter protein.


Subject(s)
Cyclic GMP/analogs & derivatives , Cyclic GMP/physiology , Kidney/metabolism , Symporters/metabolism , Animals , Atrial Natriuretic Factor/pharmacology , Cell Line , Cyclic GMP/pharmacology , Female , In Vitro Techniques , Kidney/cytology , Kidney Tubules, Proximal/metabolism , Mice , Nitric Oxide/pharmacology , Opossums , Perfusion , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type IIa , Tissue Distribution/drug effects
12.
Pflugers Arch ; 442(5): 782-90, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11512035

ABSTRACT

Type IIa and IIb Na+/Pi-cotransporters have different patterns of expression in vivo: IIa is expressed in apical membranes of renal proximal tubules, and IIb in intestinal and lung epithelia. They are found in different subcellular locations when transfected in epithelial cells: IIa is apically expressed in renal proximal cells (OK), but mostly intracellularly in intestinal cells (CaCo2); IIb is apical in both cell types. To identify the domains responsible for the different expression of both cotransporters (in CaCo2), as well as those responsible for the apical expression of IIa (in OK), mutated cotransporters were fused to the Enhanced Green Fluorescent Protein (EGFP), and their expression analyzed by confocal microscopy. We conclude that the apical expression information for CaCo2 is contained within the C-terminal tail of IIb, but is not contained within IIa. From analysis of mutated IIa cotransporters we identified residues, within the C-terminal tail, involved in the apical expression of these cotransporters in OK cells: internal PR-residues and terminal TRL-residues. These signals are functional in OK but not in CaCo2-cells, supporting the concept that polarized targeting can be protein and cell specific.


Subject(s)
Cell Polarity , Kidney/metabolism , Symporters/genetics , Amino Acid Motifs , Animals , Caco-2 Cells , Cell Line , Green Fluorescent Proteins , Humans , Luminescent Proteins/metabolism , Mice , Microscopy, Confocal , Models, Molecular , Opossums , Protein Isoforms , Recombinant Fusion Proteins/metabolism , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type IIa , Symporters/chemistry , Symporters/metabolism , Transfection
13.
Curr Opin Nephrol Hypertens ; 10(5): 555-61, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11496046

ABSTRACT

The type IIa sodium/inorganic phosphate co-transporter is the rate-limiting inorganic phosphate transport pathway in renal brush-border membranes, and is thus a key player in overall inorganic phosphate homeostasis. Its regulation is mostly associated with membrane retrieval/reinsertion (traffic) of the transport protein. This membrane traffic is controlled by specific 'motifs' at the level of the transporter protein and probably involves interacting proteins (e.g. for scaffolding, regulation or sorting). The intracellular signaling mechanisms (e.g. the involvement of kinases) and the involvement of the cytoskeleton are not yet understood. Hereditary alterations in renal inorganic phosphate handling can be associated with factors controlling the expression of the brush-border type IIa sodium/inorganic phosphate co-transporter.


Subject(s)
Kidney/metabolism , Phosphates/metabolism , Symporters/physiology , Absorption/physiology , Amino Acid Motifs/physiology , Animals , Humans , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type IIa , Symporters/genetics
14.
Kidney Int ; 60(2): 431-5, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11473622

ABSTRACT

Renal inorganic phosphate (Pi) reabsorption is a key process in Pi homeostasis. Type IIa Na/Pi cotransporters, located at the apical membrane of renal proximal tubular cells, guarantee the vectorial transport of Pi. Renal Pi reabsorption can be modulated by controlling the number of cotransporters expressed at the apical membrane. Indeed, factors that increase Pi reabsorption induce the expression of type IIa cotransporters at the apical membrane, whereas factors that decrease Pi reabsorption lead to their retrieval. Therefore, proper sorting of this type of cotransporters is an essential step in Pi homeostasis. The relevance of polarization has been highlighted by the finding that improper sorting of transporters can cause disease. Here we describe the identification of signals involved in apical expression of newly synthesized type IIa cotransporters and in their hormonal-induced endocytosis.


Subject(s)
Carrier Proteins/genetics , Carrier Proteins/metabolism , Kidney/metabolism , Phosphates/metabolism , Symporters , Animals , Gene Expression/physiology , Homeostasis/physiology , Sodium-Phosphate Cotransporter Proteins
15.
Mol Membr Biol ; 18(1): 3-11, 2001.
Article in English | MEDLINE | ID: mdl-11396609

ABSTRACT

Renal and small intestinal (re-)absorption contribute to overall phosphate(Pi)-homeostasis. In both epithelia, apical sodium (Na+)/Pi-cotransport across the luminal (brush border) membrane is rate limiting and the target for physiological/pathophysiological alterations. Three different Na/Pi-cotransporters have been identified: (i) type I cotransporter(s)--present in the proximal tubule--also show anion channel function and may play a role in secretion of organic anions; in the brain, it may serve vesicular glutamate uptake functions; (ii) type II cotransporter(s) seem to serve rather specific epithelial functions; in the renal proximal tubule (type Ila) and in the small intestine (type IIb), isoform determines Na+-dependent transcellular Pi-movements; (iii) type III cotransporters are expressed in many different cells/tissues where they could serve housekeeping functions. In the small intestine, alterations in Pi-absorption and, thus, apical expression of IIb protein are mostly in response to longer term (days) situations (altered Pi-intake, levels of 1.25 (OH2) vitamin D3, growth, etc), whereas in renal proximal tubule, in addition, hormonal effects (e.g. Parathyroid Hormone, PTH) acutely control (minutes/hours) the expression of the IIa cotransporter. The type II Na/Pi-cotransporters operate (as functional monomers) in a 3 Na+:1 Pi stoichiometry, including transfer of negatively charged (-1) empty carriers and electroneutral transfers of partially loaded carriers (1 Na+, slippage) and of the fully loaded carriers (3 Na+, 1 Pi). By a chimera (IIa/IIb) approach, and by site-directed mutagenesis (including cysteine-scanning), specific sequences have been identified contributing to either apical expression, PTH-induced membrane retrieval, Na+-interaction or specific pH-dependence of the IIa and IIIb cotransporters. For the COOH-terminal tail of the IIa Na/Pi-cotransporter, several interacting PDZ-domain proteins have been identified which may contribute to either its apical expression (NaPi-Cap1) or to its subapical/lysosomal traffic (NaPi-Cap2).


Subject(s)
Intestine, Small/metabolism , Kidney Tubules/metabolism , Phosphates/metabolism , Absorption , Amino Acid Sequence , Animals , Biological Transport , Cell Line , Endocytosis , Humans , Kinetics , Models, Biological , Molecular Sequence Data , Protein Isoforms , Protein Structure, Tertiary , Transfection , Two-Hybrid System Techniques
16.
J Physiol ; 531(Pt 2): 383-91, 2001 Mar 01.
Article in English | MEDLINE | ID: mdl-11230511

ABSTRACT

Type IIa and IIb Na+-Pi cotransporters are highly conserved proteins expressed in brush border membranes of proximal tubules and small intestine, respectively. The kinetics of IIa and IIb differ significantly: type IIb is saturated at lower concentrations of Na+ and Pi. To define the domain responsible for the difference in Na+ affinity we constructed several mouse IIa-IIb chimeras as well as site-directed mutagenized cotransporters. Pi uptake activity was determined after injection of cRNAs into Xenopus laevis oocytes. From the chimera experiments we concluded that the domain containing part of the second intracellular loop, the fifth transmembrane domain (TD) and part of the third extracellular loop determines the specific Na+ activation properties for both types of cotransporter. Within this domain only a few residues located in the fifth TD are not conserved between type IIa and IIb. Site-directed mutagenesis on non-conserved residues was performed. Substitution of F402 of IIa by the corresponding L418 from IIb yielded a cotransporter that behaved like the IIb. On the other hand, substitution of the specific L418 of IIb by the corresponding F402 of IIa produced a cotransporter with a Na+ activation similar to IIa. (Single letter amino acid nomenclature is used throughout the paper.) These data suggest that the specific Na+ activation properties exhibited by type IIa and type IIb Na+-Pi cotransporters are at least in part due to the presence of a specific amino acid (F402 in IIa, and L418 in IIb) within the fifth TD of the protein.


Subject(s)
Amino Acids/metabolism , Carrier Proteins/metabolism , Oocytes/metabolism , Sodium/metabolism , Symporters , Amino Acid Sequence/genetics , Amino Acid Substitution , Animals , Carrier Proteins/genetics , Chimera , Female , Mice , Molecular Sequence Data , Mutagenesis, Site-Directed , Protein Isoforms/genetics , Protein Structure, Tertiary/genetics , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type II , Sodium-Phosphate Cotransporter Proteins, Type IIa , Sodium-Phosphate Cotransporter Proteins, Type IIb , Xenopus laevis
17.
Proc Natl Acad Sci U S A ; 97(23): 12896-901, 2000 Nov 07.
Article in English | MEDLINE | ID: mdl-11050158

ABSTRACT

Type II NaPi cotransporters are expressed in the apical membrane of P(i)-(re)absorbing epithelia: the type IIa in renal proximal tubule and the type IIb in small intestine. Parathyroid hormone (PTH) leads to a retrieval from the apical membrane of the type IIa NaPi cotransporter. The type IIa cotransporter is also expressed in opossum kidney (OK) cells, and its expression is under the control of PTH. In the present study, we identified the molecular "domains" involved in the PTH-induced retrieval of the type IIa NaPi cotransporter. Wild-type mouse type IIa (mIIa) and type IIb (mIIb) as well as several mIIa-mIIb chimeras and site-directed mutants were fused to the enhanced green fluorescent protein and transfected into OK cells. We found that mIIa but not mIIb was internalized and degraded after incubation with 1-34 (or 3-34) PTH. Using chimeras, we found that the N and C termini were not required in this effect, whereas a "domain" located between residues 216 and 658 seemed to be necessary. This region contains two putative intracellular loops with highly conserved sequences between mIIa and mIIb; in the last intracellular loop, two charged amino acids of type IIa (K(503)R(504)) are replaced by uncharged residues in type IIb (N(520)I(521)). We generated two mutants in which these residues were interchanged: mIIaNI and mIIbKR. Similarly to mIIa, the mIIbKR mutant was endocytosed in response to 1-34 PTH; in contrast, mIIaNI behaved as mIIb and was not internalized. In conclusion, a dibasic amino acid motif (K(503)R(504)) located in the last intracellular loop of the type IIa NaPi cotransporter is essential for its PTH-induced retrieval.


Subject(s)
Carrier Proteins/metabolism , Down-Regulation , Parathyroid Hormone/metabolism , Peptide Fragments/metabolism , Symporters , Amino Acid Motifs , Amino Acid Sequence , Animals , Carrier Proteins/genetics , Cell Line , Gene Expression , Humans , Mice , Molecular Sequence Data , Mutagenesis , Opossums , Parathyroid Hormone/pharmacology , Peptide Fragments/pharmacology , Recombinant Fusion Proteins/genetics , Sequence Homology, Amino Acid , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type II , Sodium-Phosphate Cotransporter Proteins, Type IIa , Sodium-Phosphate Cotransporter Proteins, Type IIb
18.
Physiol Rev ; 80(4): 1373-409, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11015617

ABSTRACT

Renal proximal tubular reabsorption of P(i) is a key element in overall P(i) homeostasis, and it involves a secondary active P(i) transport mechanism. Among the molecularly identified sodium-phosphate (Na/P(i)) cotransport systems a brush-border membrane type IIa Na-P(i) cotransporter is the key player in proximal tubular P(i) reabsorption. Physiological and pathophysiological alterations in renal P(i) reabsorption are related to altered brush-border membrane expression/content of the type IIa Na-P(i) cotransporter. Complex membrane retrieval/insertion mechanisms are involved in modulating transporter content in the brush-border membrane. In a tissue culture model (OK cells) expressing intrinsically the type IIa Na-P(i) cotransporter, the cellular cascades involved in "physiological/pathophysiological" control of P(i) reabsorption have been explored. As this cell model offers a "proximal tubular" environment, it is useful for characterization (in heterologous expression studies) of the cellular/molecular requirements for transport regulation. Finally, the oocyte expression system has permitted a thorough characterization of the transport characteristics and of structure/function relationships. Thus the cloning of the type IIa Na-P(i )cotransporter (in 1993) provided the tools to study renal brush-border membrane Na-P(i) cotransport function/regulation at the cellular/molecular level as well as at the organ level and led to an understanding of cellular mechanisms involved in control of proximal tubular P(i) handling and, thus, of overall P(i) homeostasis.


Subject(s)
Kidney Tubules, Proximal/metabolism , Phosphates/metabolism , Symporters , Absorption/physiology , Animals , Biological Transport, Active/physiology , Carrier Proteins/genetics , Carrier Proteins/metabolism , Electrophysiology , Gene Expression Regulation/physiology , Mice , Microvilli/metabolism , Phylogeny , Protein Isoforms/genetics , Protein Isoforms/metabolism , Protein Structure, Secondary/genetics , Rabbits , Rats , Sequence Homology, Amino Acid , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type IIa
19.
Exp Nephrol ; 8(6): 366-75, 2000.
Article in English | MEDLINE | ID: mdl-11014934

ABSTRACT

A key process in overall P(i)-homeostasis is renal proximal tubular reabsorption of inorganic phosphate (P(i)), which involves secondary active sodium/phosphate (Na(+)/P(i)) cotransport reabsorption at the brush border membrane. Among the two different molecularly identified Na(+)/P(i) cotransporters, the type-IIa Na(+)/P(i) cotransporter (NaPi-IIa) accounts for up to 70% of brush border membrane transport. Regulation of renal P(i) reabsorption centers around brush border membrane insertion and retrieval of transporter protein under the influence of hormonal and nonhormonal factors. Immunohistochemical and fluorescence techniques have provided new insights into the tissue distribution and the regulation processes. The intrinsic electrogenicity of NaPi-IIa, has allowed detailed studies of the transport kinetics of NaPi-IIa and, combined with mutagenesis methods, structure-function information at the protein level is emerging.


Subject(s)
Carrier Proteins/genetics , Carrier Proteins/physiology , Symporters , Amino Acid Sequence/genetics , Animals , Carrier Proteins/chemistry , Carrier Proteins/metabolism , Down-Regulation , Humans , Kidney/metabolism , Kinetics , Molecular Sequence Data , Phosphate-Binding Proteins , Protein Structure, Secondary , RNA, Messenger/metabolism , Sodium-Phosphate Cotransporter Proteins , Sodium-Phosphate Cotransporter Proteins, Type IIa , Structure-Activity Relationship , Up-Regulation
20.
BJU Int ; 86(4): 432-8, 2000 Sep.
Article in English | MEDLINE | ID: mdl-10971267

ABSTRACT

OBJECTIVE: To assess the effect of the age of patients with benign prostatic hyperplasia (BPH) on the clinical uroselectivity of alfuzosin during general medical practice. PATIENTS AND METHODS: The present national, multicentre, open-labelled, observational study involved 4018 Spanish outpatients with BPH, i.e. showing lower urinary tract symptoms (LUTS) suggestive of benign prostatic obstruction. The patients received sustained release (SR) alfuzosin, 5 mg twice daily, for 2 months. The primary efficacy criteria were symptomatic improvements, as assessed by the International Prostate Symptom Score (IPSS) and quality of life (QoL) index. Safety was assessed by monitoring cardiovascular data and adverse events. RESULTS: The patients were divided into four age groups, i.e. < 56, 56-65, 66-75 and > 75 years. All groups of patients showed a mean IPSS decrease of 11-12 (55.8-65.4% from baseline) at the end of the study, while the QoL decreased by 2-3 points (55.6-63.6% from baseline). There were no relevant effects of age on the efficacy of the treatment. Moreover, alfuzosin was well tolerated independently of the age of the patient; 1.2% of the patients enrolled withdrew because of adverse events. The qualitative distribution of vasodilatory/nonvasodilatory adverse events was similar in all age groups. The incidence of asymptomatic orthostatic hypotension was low (0.58%) and not affected by the age of the patients. CONCLUSION: This study confirms that the clinical uro-selectivity of SR-alfuzosin, already described in ran-domized controlled studies, is not significantly affected in clinical practice by the age of the patients. This is considered particularly relevant to the characteristics of patients with BPH, as they are mostly elderly men.


Subject(s)
Adrenergic alpha-Antagonists/therapeutic use , Prostatic Hyperplasia/drug therapy , Quinazolines/therapeutic use , Adult , Age Factors , Aged , Humans , Male , Middle Aged , Quality of Life , Treatment Outcome , Urination Disorders/drug therapy
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