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1.
Arch. argent. pediatr ; 122(2): e202202948, abr. 2024. tab
Artigo em Inglês, Espanhol | LILACS, BINACIS | ID: biblio-1537622

RESUMO

Objetivo. Proporcionar un marco para profesionales de la salud que tratan a pacientes pediátricos bajo terapia con glucocorticoides (GC) y desarrollar recomendaciones para la prevención y el tratamiento de la osteoporosis inducida por GC en la población pediátrica. Métodos. Un panel de expertos en enfermedades óseas y pediátricas generó una serie de preguntas PICO que abordan aspectos relacionados con la prevención y el tratamiento de osteoporosis en pacientes bajo tratamiento con GC. Siguiendo la metodología GRADE, se realizó una revisión sistemática de la literatura, se resumieron las estimaciones del efecto y se calificó la calidad de la evidencia. Luego se procedió a la votación y a la formulación de las recomendaciones. Resultados. Se desarrollaron 7 recomendaciones y 6 principios generales para osteoporosis inducida por GC en población pediátrica. Conclusión. Estas recomendaciones proporcionan orientación para los médicos que deben tomar decisiones en pacientes pediátricos bajo tratamiento con GC.


Objective. To provide a framework for healthcare professionals managing pediatric patients who are on active glucocorticoid (GC) therapy and to develop recommendations for the prevention and treatment of GC-induced osteoporosis in the pediatric population. Methods. A panel of experts on bone and pediatric diseases developed a series of PICO questions that address issues related to the prevention and treatment of osteoporosis in patients on GC therapy. In accordance with the GRADE approach, we conducted a systematic review of the literature, summarized effect estimations, and classified the quality of the evidence. Then, voting and the formulation of recommendations followed. Results. Seven recommendations and six general principles were developed for GC-induced osteoporosis in the pediatric population. Conclusion. These recommendations provide guidance for clinicians who must make decisions concerning pediatric patients undergoing treatment with GC.


Assuntos
Humanos , Criança , Osteoporose/induzido quimicamente , Osteoporose/prevenção & controle , Osteoporose/tratamento farmacológico , Glucocorticoides/efeitos adversos
2.
Arch Argent Pediatr ; 122(2): e202202948, 2024 04 01.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-37382585

RESUMO

Objective. To provide a framework for healthcare professionals managing pediatric patients who are on active glucocorticoid (GC) therapy and to develop recommendations for the prevention and treatment of GC-induced osteoporosis in the pediatric population. Methods. A panel of experts on bone and pediatric diseases developed a series of PICO questions that address issues related to the prevention and treatment of osteoporosis in patients on GC therapy. In accordance with the GRADE approach, we conducted a systematic review of the literature, summarized effect estimations, and classified the quality of the evidence. Then, voting and the formulation of recommendations followed. Results. Seven recommendations and six general principles were developed for GC-induced osteoporosis in the pediatric population. Conclusion. These recommendations provide guidance for clinicians who must make decisions concerning pediatric patients undergoing treatment with GC.


Objetivo. Proporcionar un marco para profesionales de la salud que tratan a pacientes pediátricos bajo terapia con glucocorticoides (GC) y desarrollar recomendaciones para la prevención y el tratamiento de la osteoporosis inducida por GC en la población pediátrica. Métodos. Un panel de expertos en enfermedades óseas y pediátricas generó una serie de preguntas PICO que abordan aspectos relacionados con la prevención y el tratamiento de osteoporosis en pacientes bajo tratamiento con GC. Siguiendo la metodología GRADE, se realizó una revisión sistemática de la literatura, se resumieron las estimaciones del efecto y se calificó la calidad de la evidencia. Luego se procedió a la votación y a la formulación de las recomendaciones. Resultados. Se desarrollaron 7 recomendaciones y 6 principios generales para osteoporosis inducida por GC en población pediátrica. Conclusión. Estas recomendaciones proporcionan orientación para los médicos que deben tomar decisiones en pacientes pediátricos bajo tratamiento con GC.


Assuntos
Glucocorticoides , Osteoporose , Humanos , Criança , Glucocorticoides/efeitos adversos , Osteoporose/induzido quimicamente , Osteoporose/tratamento farmacológico , Osteoporose/prevenção & controle
3.
4.
J Clin Rheumatol ; 29(5): e59-e70, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37005371

RESUMO

OBJECTIVE: The aim of this study was to provide an evidence-based framework to guide health care professionals treating patients under glucocorticoid (GC) therapy and develop guidelines for the prevention and treatment of glucocorticoid-induced osteoporosis (GIO) in postmenopausal women and men aged ≥50 years. METHODS: An expert panel on bone diseases designed a series of clinically meaningful questions following the PICO (Population, Intervention, Comparator, and Outcome) structure. Using GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology, we made a systematic literature review, extracted and summarized the effect estimates, and graded the quality of the evidence. The expert panel voted each PICO question and made recommendations after reaching an agreement of at least 70%. RESULTS: Seventeen recommendations (9 strong and 8 conditional) and 8 general principles were developed for postmenopausal women and men aged ≥50 years under GC treatment. Bone mineral density (BMD), occurrence of fragility fractures, probability of fracture at 10 years by Fracture Risk Assessment Tool, and other screening factors for low BMD are recommended for patient evaluation and stratification according to fragility fracture risk. The treatment of patients under GC therapy should include counseling on lifestyle habits and strict control of comorbidities. The goal of GIO treatment is the nonoccurrence of new fragility fractures as well as to increase or maintain BMD in certain clinical situations. This was considered for the therapeutic approach in different clinical scenarios. CONCLUSIONS: This GIO guideline provides evidence-based guidance for health care providers treating patients.


Assuntos
Glucocorticoides , Osteoporose , Masculino , Humanos , Feminino , Pessoa de Meia-Idade , Idoso , Glucocorticoides/uso terapêutico , Pós-Menopausa , Osteoporose/induzido quimicamente , Osteoporose/diagnóstico , Osteoporose/tratamento farmacológico , Densidade Óssea
5.
Lancet Rheumatol ; 4(12): e864-e872, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38261393

RESUMO

Considerable variability exists in the way that health-care providers treat patients with giant cell arteritis in Latin America, with patients commonly exposed to excessive amounts of glucocorticoids. In addition, large health disparities prevail in this region due to socioeconomic factors, which influence access to care, including biological treatments. For these reasons, the Pan American League of Associations for Rheumatology developed the first evidence-based giant cell arteritis treatment guidelines tailored for Latin America. A panel of vasculitis experts from Mexico, Colombia, Peru, Brazil, and Argentina generated clinically meaningful questions related to the treatment of giant cell arteritis in the population, intervention, comparator, and outcome (PICO) format. Following the grading of recommendations, assessment, development, and evaluation methodology, a team of methodologists did a systematic literature search, extracted and summarised the effects of the interventions, and graded the quality of the evidence. The panel of vasculitis experts voted on each PICO question and made recommendations, which required at least 70% agreement among the voting members to be included in the guidelines. Nine recommendations and one expert opinion statement for the treatment of giant cell arteritis were developed considering the most up-to-date evidence and the socioeconomic characteristics of Latin America. These recommendations include guidance for the use of glucocorticoids, tocilizumab, methotrexate, and aspirin for patients with giant cell arteritis.


Assuntos
Arterite de Células Gigantes , Reumatologia , Humanos , Arterite de Células Gigantes/tratamento farmacológico , Argentina , Aspirina , Brasil , Glucocorticoides/uso terapêutico
6.
Clin Respir J ; 12(7): 2220-2227, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29570946

RESUMO

INTRODUCTION: Community-acquired pneumonia (CAP) is the infectious disease with the highest number of deaths worldwide. Several studies have shown an association between vitamin D deficiency and increases susceptibility to respiratory tract infections. OBJECTIVE: The aim of this study was to evaluate the serum 25-hydroxyvitamin D (25OHD) levels in hospitalized adults in general room with CAP. MATERIALS AND METHODS: An observational study was carried out in 207 hospitalized adults of both sex with CAP (>18 years) from Rosario city, Argentina (32° 52' 18″S) between July 2015 and June 2016. RESULTS: In total, 167 patients were included in the data analysis [59% women (57.4 ± 19.6 years), body mass index 27.2 ± 7.8 kg/m2 ]. In brief, 63% showed unilobar infiltrate and 37% were multilobar. The CURB-65 index was 66.5% low risk, 16.0% intermediate risk and 17.5% high risk. According to Charlson comorbidity index (CCI) 53.5% had not comorbidity (CCI = 0) and 46.5% showed CCI ≥ 1. The 25OHD level was: 11.92 ± 7.6 ng/mL (51.5%: <10 ng/mL, 33.5%: 10-20 ng/mL, 13.2%: 20-30 ng/mL and 1.8%: >30 ng/mL). Higher 25OHD were found in male (female: 10.8 ± 6.7 ng/mL, male: 13.5 ± 8.5 ng/mL, P = .02) and 25OHD correlated with age (r = -.17; P = .02). 25-Hydroxyvitamin D was also correlated with CURB65 index (r = -.13; P = .049), CCI (r = -.20, P = .007) and with the 10 years of life expectative (%) (r = .19; P = .008). In addition, higher 25OHD were found with lower CCI (CCI 0 = 13.0 ± 8.2 ng/mL, CCI ≥ 1= 10.5 ± 6.7 ng/mL; P = .0093). CONCLUSIONS: Hospitalized adults with CAP have lower 25OHD levels and would be associated with the severity of CAP.


Assuntos
Infecções Comunitárias Adquiridas/sangue , Pneumonia/sangue , Deficiência de Vitamina D/diagnóstico , Vitamina D/análogos & derivados , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Argentina , Feminino , Hospitalização , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Vitamina D/sangue
8.
Actual. osteol ; 13(1): 9-16, Ene - Abr. 2017. tab
Artigo em Espanhol | LILACS | ID: biblio-1118618

RESUMO

Tanto el ranelato de estroncio (RSr) como el denosumab (Dmab) son eficaces en el tratamiento de la osteoporosis (OP) posmenopáusica (PM). El efecto de cada fármaco por separado sobre la densidad mineral ósea (DMO) ha sido estudiado recientemente. Con ambas drogas se observó, al año de tratamiento, un aumento significativo de la DMO en columna lumbar (CL), cuello femoral (CF) y cadera total (CT). En este trabajo comparamos la respuesta densitométrica al año de tratamiento con una y otra droga. Utilizamos los registros de 425 pacientes PMOP tratadas con Dmab y 441 tratadas con RSr. En cada paciente analizamos el porcentaje de cambio; se clasificaron como respondedoras aquellas que mostraron un cambio ≥3%. Adicionalmente se comparó la respuesta en pacientes no previamente tratadas con bifosfonatos (BF-naïve) en comparación con pacientes que habían recibido previamente un BF. Al analizar el grupo completo para Dmab, el porcentaje de pacientes respondedoras fue de 68,4% en CL, 63,3% en CF y 49,3% en CT. Por otro lado, en el grupo de pacientes tratadas con RSr, el porcentaje de respondedoras (53,8% en CL, 40,0% en CF y 35,6% en CT) fue estadísticamente menor. Cuando comparamos la respuesta entre las pacientes BF-naïve que recibieron RSr o Dmab, el Dmab indujo mayor respuesta en CL y CF que el grupo RSr, sin diferencias en CT. Cuando se analizaron los subgrupos BF-previo, las tratadas con Dmab mostraron mayor respuesta en todas las regiones. Conclusión: en pacientes con OP-PM, el tratamiento con Dmab produjo mayores incrementos densitométricos que el RSr, siendo el porcentaje de pacientes respondedoras mayor con Dmab que con RSr. (AU)


Both strontium ranelate (SrR) and denosumab (Dmab) are effective in the treatment of postmenopausal osteoporosis (PMOP). The effect of each drug on bone mineral density (BMD) has been studied separately by us. With both treatments, there was a significant increase after one year of treatment at the lumbar spine (LS) and hip. In this paper we compared the densitometric response after one year of treatment with both drugs used separately. We used the clinical records of 425 PM patients treated with Dmab and 441 treated with SrR. For each patient we analyzed the percentage of change; those who showed a change ≥3% were classified as responders. Additionally, the response was compared in patients not previously treated with bisphosphonates (BP-naïve) compared to patients who had previously received a BP. When analyzing the complete group for Dmab, the percentage of "responders" was 65.2% at the LS, 62.9% at the femoral neck (FN) and 47.4% at the total hip (TH). On the other hand, in the group of patients treated with SrR the percentage of responders (53.8% at the LS, 40.0% at the FN and 35.6% at the TH) was statistically lower. When comparing the response between in BF-naïve patients receiving RSr or Dmab, Dmab induced a greater response at the LS and FN than the RSr group, with no statistical differences at the TH. When the subgroups with prior BP treatment were analyzed, those treated with Dmab showed greater response in all regions. Conclusion: in patients with PMOP treatment with Dmab produced greater densitometric increments than SrR, and the percentage of responders was higher with Dmab than with SrR. (AU)


Assuntos
Humanos , Feminino , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Estrôncio/uso terapêutico , Osteoporose Pós-Menopausa/tratamento farmacológico , Denosumab/uso terapêutico , Fosfatos/sangue , Estrôncio/administração & dosagem , Estrôncio/química , Vitamina D/administração & dosagem , Biomarcadores , Densidade Óssea/efeitos dos fármacos , Fraturas de Estresse/prevenção & controle , Osteocalcina/sangue , Osteoporose Pós-Menopausa/sangue , Cálcio/administração & dosagem , Cálcio/sangue , Estudos Retrospectivos , Teriparatida/uso terapêutico , Densitometria , Difosfonatos/uso terapêutico , Fosfatase Alcalina/sangue , Conservadores da Densidade Óssea/uso terapêutico , Colo do Fêmur/efeitos dos fármacos , Denosumab/administração & dosagem , Cooperação e Adesão ao Tratamento , Quadril , Região Lombossacral
9.
Calcif Tissue Int ; 97(5): 527-34, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26223790

RESUMO

Yerba mate (Ilex paraguariensis) is a xanthine-containing beverage, which is also rich in caffeine. Because caffeine has a negative impact on bone mineral density (BMD) mainly associated with low calcium (Ca) diets, there would be expected a negative effect of yerba mate on bone. In this study, Sprague-Dawley rats were used and randomly assigned into four groups (n = 6/group): Control + Ca 0.2 g %; Control + Ca 0.9 g %; Yerba + Ca 0.2 g %; Yerba + Ca 0.9 g %. At the end of the experiment, tibias and femurs were obtained for BMD, morphometric, histomorphometric, and biomechanical analyses. While there was no difference in bone parameters between rats with and without yerba mate consumption, a negative effect of low Ca diet was observed in BMD, morphometric, histomorphometric, and biomechanical results. Interaction between Ca content in the diet and yerba mate was only found in trabecular bone volume, which would indicate that the negative effect of low Ca intake on bone volume is reversed in part by yerba mate infusion. However, yerba mate was not able to reverse the negative effect of low Ca content on biomechanical properties and trabecular connectivity. In summary, at least in our study, yerba mate would not have a negative effect on bone and would be safe for the bone health of consumers.


Assuntos
Doenças Ósseas/patologia , Cálcio da Dieta/metabolismo , Ilex paraguariensis/toxicidade , Extratos Vegetais/toxicidade , Absorciometria de Fóton , Animais , Densidade Óssea/efeitos dos fármacos , Doenças Ósseas/induzido quimicamente , Feminino , Ratos , Ratos Sprague-Dawley
10.
Rheumatol Int ; 35(3): 499-505, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24980067

RESUMO

Rheumatoid arthritis (RA) is a chronic systemic inflammatory autoimmune disease with high prevalence of osteoporosis. Previous evidence indicates an association between vitamin D deficiency and autoimmune diseases. The aim of this study was to evaluate serum 25 hydroxyvitamin D [25(OH)D] levels, bone mineral density (BMD) and disease activity in RA patients living in Argentina. We studied 34 RA women and 41 healthy women as a control group. RA patients had lower 25(OH)D levels (20.4 ± 0.9 ng/ml) than controls (26.3 ± 1.9 ng/ml; p < 0.05). No significant differences were found in lumbar spine BMD between premenopausal (preM) or postmenopausal (postM) patients, but femoral neck BMD was significantly lower in postM RA patients (T score -2.5 ± 0.4) than in postM control subjects (T score -0.9 ± 0.3, p = 0.014). Although no linear correlation between 25(OH)D levels and disease activity (DAS-28) was found, patients with moderate-high disease activity had lower 25(OH)D levels than those with low disease activity: DAS-28 >3.2: 19.5 ± 0.88 ng/ml; DAS-28 ≤3.2: 23.7 ± 2.8 ng/ml (p = 0.047). After 1 year of vitamin D treatment 25(OH)D levels were increased while DAS-28 were decreased (n = 25; p < 0.05). We conclude that patients with RA had lower 25(OH)D levels than the control group. Low levels of 25(OH)D were associated with moderate-high disease activity suggesting the importance of optimal 25(OH)D levels in RA patients. Femoral neck BMD was lower in postM RA patients. No differences in lumbar BMD were found between preM and postM RA patients, suggesting that bone mass evaluation in RA patients should include femoral neck BMD regardless of age.


Assuntos
Artrite Reumatoide/fisiopatologia , Colo do Fêmur/diagnóstico por imagem , Vértebras Lombares/diagnóstico por imagem , Deficiência de Vitamina D/sangue , Vitamina D/análogos & derivados , Absorciometria de Fóton , Adulto , Idoso , Antirreumáticos/uso terapêutico , Argentina , Artrite Reumatoide/complicações , Artrite Reumatoide/tratamento farmacológico , Densidade Óssea , Feminino , Humanos , Pessoa de Meia-Idade , Pós-Menopausa , Pré-Menopausa , Índice de Gravidade de Doença , Resultado do Tratamento , Vitamina D/sangue , Vitamina D/uso terapêutico , Deficiência de Vitamina D/complicações , Deficiência de Vitamina D/diagnóstico por imagem , Deficiência de Vitamina D/tratamento farmacológico , Adulto Jovem
11.
Springerplus ; 3: 676, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25520906

RESUMO

The aim of this study was to evaluate the effect of strontium ranelate (SrR) on bone mineral density (BMD) and bone turnover markers after 1 year of treatment. Additionally, the effect of SrR in bisphosphonate-naïve patients (BP-naïve) compared to patients previously treated with bisphosphonates (BP-prior) was analyzed. This retrospective study included 482 postmenopausal women treated with SrR (2 g/day) for 1 year in ten Argentine centers; 41 patients were excluded due to insufficient data, while 441 were included. Participants were divided according to previous bisphosphonate treatment in two groups: BP-naïve (n = 87) and BP-prior (n = 350). Data are expressed as mean ± SEM. After 1 year of treatment with SrR the bone formation markers total alkaline phosphatase and osteocalcin were increased (p < 0.0001), while the bone resorption marker s-CTX was decreased (p = 0.0579). Also increases in BMD at the lumbar spine (LS, 3.73%), femoral neck (FN, 2.00%) and total hip (TH, 1.54%) [p < 0.0001] were observed. These increments were significant (p < 0.0001) both among BP-naïve and BP-prior patients. Interestingly, the change in BMD after 1 year of SrR treatment was higher in BP-naïve patients: LS: BP-naïve = 4.58 ± 0.62%; BP-prior = 3.45 ± 0.28% (p = 0.078). FN: BP-naïve = 2.79 ± 0.56%; BP-prior = 2.13 ± 0.29% (p = 0.161). TH: BP-naïve = 3.01 ± 0.55%; BP-prior = 1.22 ± 0.27% (p = 0.0006). SrR treatment increased BMD and bone formation markers and decreased a bone resorption marker in the whole group, with better response in BP-naïve patients.

12.
Mol Nutr Food Res ; 58(7): 1546-51, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24753180

RESUMO

SCOPE: Intestinal alkaline phosphatase is a brush border enzyme that is stimulated by calcium. Inhibition of intestinal alkaline phosphatase increases intestinal calcium absorption. We hypothesized that intestinal alkaline phosphatase acts as a minute-to-minute regulatory mechanism of calcium entry. The aim of this study was to evaluate the mechanism by which intestinal luminal calcium controls intestinal calcium absorption. METHODS AND RESULTS: We performed kinetic studies with purified intestinal alkaline phosphatase and everted duodenal sacs and showed that intestinal alkaline phosphatase modifies the luminal pH as a function of enzyme concentration and calcium luminal content. A decrease in pH occurred simultaneously with a decrease in calcium absorption. The inhibition of intestinal alkaline phosphatase by l-phenylalanine caused an increase in calcium absorption. This effect was also confirmed in calcium uptake experiments with isolated duodenal cells. CONCLUSION: Changes in luminal pH arising from intestinal alkaline phosphatase activity induced by luminal calcium concentration modulate intestinal calcium absorption.


Assuntos
Fosfatase Alcalina/metabolismo , Cálcio/administração & dosagem , Absorção Intestinal , Intestinos/enzimologia , Fosfatase Alcalina/antagonistas & inibidores , Animais , Cálcio/farmacocinética , Duodeno/citologia , Duodeno/efeitos dos fármacos , Duodeno/metabolismo , Feminino , Concentração de Íons de Hidrogênio , Microvilosidades/efeitos dos fármacos , Microvilosidades/metabolismo , Fenilalanina/farmacologia , Ratos , Ratos Sprague-Dawley
13.
Br J Nutr ; 108(2): 229-33, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22018098

RESUMO

Intestinal alkaline phosphatase (IAP) is a brush-border phosphomonoesterase. Its location suggests an involvement in the uptake of nutrients, but its role has not yet been defined. IAP expression parallels that of other proteins involved in Ca absorption under vitamin D stimulation. Experiments carried out in vitro with purified IAP have demonstrated an interaction between Ca and IAP. The gut is prepared to face different levels of Ca intake over time, but high Ca intake in a situation of a low-Ca diet over time would cause excessive entry of Ca into the enterocytes. The presence of a mechanism to block Ca entry and to avoid possible adverse effects is thus predictable. Thus, in the present study, Sprague-Dawley rats were fed with different amounts of Ca in the diet (0.2, 1 and 2 g%), and the percentage of Ca absorption (%Ca) in the presence and absence of L-phenylalanine (Phe) was calculated. The presence of Phe caused a significant increase in %Ca (52.3 (SEM 6.5) % in the presence of Phe v. 31.1 (sem 8.9) % in the absence of Phe, regardless of the amount of Ca intake; paired t test, P = 0.02). When data were analysed with respect to Ca intake, a significant difference was found only in the group with low Ca intake (paired t test, P = 0.03). Additionally, IAP activity increased significantly (ANOVA, P < 0.05) as Ca concentrations increased in the duodenal lumen. The present study provides in vivo evidence that luminal Ca concentration increases the activity of IAP and simultaneously decreases %Ca, acting as a minute-to-minute regulatory mechanism of Ca entry.


Assuntos
Fosfatase Alcalina/metabolismo , Cálcio da Dieta/metabolismo , Duodeno/enzimologia , Absorção Intestinal , Mucosa Intestinal/enzimologia , Isoenzimas/metabolismo , Fosfatase Alcalina/antagonistas & inibidores , Fosfatase Alcalina/química , Animais , Western Blotting , Cloreto de Cálcio/metabolismo , Cálcio da Dieta/administração & dosagem , Cálcio da Dieta/análise , Duodeno/citologia , Duodeno/efeitos dos fármacos , Duodeno/metabolismo , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Fezes/química , Conteúdo Gastrointestinal/química , Histocitoquímica , Imuno-Histoquímica , Absorção Intestinal/efeitos dos fármacos , Mucosa Intestinal/citologia , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Isoenzimas/antagonistas & inibidores , Isoenzimas/química , Masculino , Concentração Osmolar , Fenilalanina/farmacologia , Ratos , Ratos Sprague-Dawley
14.
J Enzyme Inhib Med Chem ; 21(6): 757-63, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17252950

RESUMO

Two fractions of rat intestinal alkaline phosphatase (IAP) were detected by Western blot: 168 +/- 6 and 475 +/- 45 kDa. The low molecular weight fraction constitutes 43% of the isolated proteins exhibiting 82% of the enzymatic activity, and a heavier fraction constitutes 57% of the isolated proteins and has 18% of the enzymatic activity. Calcium produced an increase of the 475-kDa form to the detriment of the 168-kDa form. This work also describes the kinetic and structural changes of IAP as a function of calcium concentration. With [Ca2+] < 10 mmole/L, the Ca(2+)-IAP interaction fitted a binding model with 7.8 +/- 4.4 moles of Ca2+ /mole of protein, affinity constant = 19.1 +/- 8.4 L/mmole, and enzymatic activity increased as a linear function of [Ca2+] (r = 0.946 p < 0.01). On the other hand, with [Ca2+] > 10 mmole/L the data did not fit this model and, the enzymatic activity decreased as a function of [Ca2+] (r = - 0.703 p < 0.05).


Assuntos
Fosfatase Alcalina/metabolismo , Cálcio/farmacologia , Intestinos/enzimologia , Fosfatase Alcalina/isolamento & purificação , Animais , Cromatografia em Gel , Relação Dose-Resposta a Droga , Feminino , Cinética , Ratos , Ratos Endogâmicos
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