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Adipose triglyceride lipase (ATGL) is involved in lipolysis and displays a detrimental pathophysiological role in cardio-metabolic diseases. However, the organo-protective effects of ATGL-induced lipolysis were also suggested. The aim of this work was to characterize the function of lipid droplets (LDs) and ATGL-induced lipolysis in the regulation of endothelial function. ATGL-dependent LDs hydrolysis and cytosolic phospholipase A2 (cPLA2)-derived eicosanoids production were studied in the aorta, endothelial and smooth muscle cells exposed to exogenous oleic acid (OA) or arachidonic acid (AA). Functional effects of ATGL-dependent lipolysis and subsequent activation of cPLA2/PGI2 pathway were also studied in vivo in relation to postprandial endothelial dysfunction.The formation of LDs was invariably associated with elevated production of endogenous AA-derived prostacyclin (PGI2). In the presence of the inhibitor of ATGL or the inhibitor of cytosolic phospholipase A2, the production of eicosanoids was reduced, with a concomitant increase in the number of LDs. OA administration impaired endothelial barrier integrity in vitro that was further impaired if OA was given together with ATGL inhibitor. Importantly, in vivo, olive oil induced postprandial endothelial dysfunction that was significantly deteriorated by ATGL inhibition, cPLA2 inhibition or by prostacyclin (IP) receptor blockade.In summary, vascular LDs formation induced by exogenous AA or OA was associated with ATGL- and cPLA2-dependent PGI2 production from endogenous AA. The inhibition of ATGL resulted in an impairment of endothelial barrier function in vitro. The inhibition of ATGL-cPLA2-PGI2 dependent pathway resulted in the deterioration of endothelial function upon exposure to olive oil in vivo. In conclusion, vascular ATGL-cPLA2-PGI2 dependent pathway activated by lipid overload and linked to LDs formation in endothelium and smooth muscle cells has a vasoprotective role by counterbalancing detrimental effects of lipid overload on endothelial function.
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Eicosanoides , Lipólise , Lipólise/fisiologia , Azeite de Oliva , Ácido Araquidônico/metabolismo , Eicosanoides/metabolismo , Prostaglandinas I/metabolismo , Fosfolipases/metabolismoRESUMO
OBJECTIVE: Decision-making between mental health clinicians and patients is under-researched. We tested whether mental health patients are more satisfied with a decision made (i) using their preferred decision-making style and (ii) with a clinician with the same decision-making style preference. METHOD: As part of the CEDAR Study (ISRCTN75841675), a convenience sample of 445 patients with severe mental illness from six European countries were assessed for desired clinical decision-making style (rated by patients and paired clinicians), decision-specific experienced style and satisfaction. RESULTS: Patients who experienced more involvement in decision-making than they desired rated higher satisfaction (OR=2.47, P=0.005, 95% CI 1.32-4.63). Decisions made with clinicians whose decision-making style preference was for more active involvement than the patient preference were rated with higher satisfaction (OR=3.17, P=0.003, 95% CI 1.48-6.82). CONCLUSION: More active involvement in decision-making than the patient stated as desired was associated with higher satisfaction. A clinical orientation towards empowering, rather than shared, decision-making may maximise satisfaction.
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Transtornos Mentais , Participação do Paciente , Padrões de Prática Médica/estatística & dados numéricos , Adulto , Europa (Continente) , Feminino , Humanos , Masculino , Transtornos Mentais/psicologia , Transtornos Mentais/terapia , Serviços de Saúde Mental/normas , Serviços de Saúde Mental/estatística & dados numéricos , Pessoa de Meia-Idade , Participação do Paciente/psicologia , Participação do Paciente/estatística & dados numéricos , Preferência do Paciente , Satisfação Pessoal , Relações Médico-Paciente , Melhoria de Qualidade , Inquéritos e QuestionáriosRESUMO
Climate change is expected to increase the frequency and intensity of summer droughts. Sufficient drought resistance, the ability to acclimate to and/or recover after drought, is thus crucial for forest tree species. However, studies on the hydraulics of mature trees during and after drought in natura are scarce. In this study, we analysed trunk water content (electrical resistivity: ER) and further hydraulic (water potential, sap flow density, specific hydraulic conductivity, vulnerability to embolism) as well as wood anatomical traits (tree ring width, conduit diameter, conduit wall reinforcement) of drought-stressed (artificially induced summer drought via throughfall-exclusion) and unstressed Picea abies and Fagus sylvatica trees. In P. abies, ER indicated a strong reduction in trunk water content after 5 years of summer drought, corresponding to significantly lower pre-dawn leaf water potential and xylem sap flow density. Vulnerability to embolism tended to be higher in drought-stressed trees. In F. sylvatica, only small differences between drought-stressed and control trees were observed. Re-watering led to a rapid increase in water potentials and xylem sap flow of both drought-stressed trees, and to increased growth rates in the next growing season. ER analyses revealed lower trunk water content in P. abies trees growing on throughfall-exclusion plots even 1 year after re-watering, indicating a limited capacity to restore internal water reserves. Results demonstrated that P. abies is more susceptible to recurrent summer drought than F. sylvatica, and can exhibit long-lasting and pronounced legacy effects in trunk water reserves.
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Abies , Fagus , Picea , Pinus , Secas , Estações do Ano , Árvores , ÁguaRESUMO
Poststernotomy mediastinitis following median sternotomy procedures such as open heart surgery is a rare complication which nevertheless has a mortality rate of up to 50 %. Several treatment options are currently available; however, none of them are standardized. Based on the experience gained from open heart surgery performed at the MediClin Heart Institute Lahr/Baden, a therapeutic algorithm was developed. The treatment steps consist of repeated radical surgical debridement, sternal restabilization, vacuum-assisted closure therapy (VAC) as well as a surgical reconstruction via M. pectoralis plasty (MPP). This approach had a 30-day mortality of 0 % and a hospital mortality of 10.4 %. The approach proved to be safe and advantageous for specific patient groups operated on at the MediClin Heart Institute Lahr/Baden.
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Infecções Bacterianas/complicações , Mediastinite/microbiologia , Esternotomia/efeitos adversos , Infecção da Ferida Cirúrgica/microbiologia , Idoso , Algoritmos , Antibacterianos/uso terapêutico , Infecções Bacterianas/diagnóstico , Infecções Bacterianas/mortalidade , Infecções Bacterianas/terapia , Estudos de Casos e Controles , Desbridamento , Drenagem , Feminino , Humanos , Pacientes Internados , Masculino , Mediastinite/diagnóstico , Mediastinite/mortalidade , Mediastinite/cirurgia , Mediastinite/terapia , Tratamento de Ferimentos com Pressão Negativa/métodos , Músculos Peitorais/transplante , Procedimentos de Cirurgia Plástica/métodos , Padrões de Referência , Reoperação , Fatores de Risco , Infecção da Ferida Cirúrgica/complicações , Infecção da Ferida Cirúrgica/diagnóstico , Infecção da Ferida Cirúrgica/mortalidade , Infecção da Ferida Cirúrgica/terapia , Análise de Sobrevida , Resultado do Tratamento , CicatrizaçãoRESUMO
BACKGROUND: Mature cystic teratomas are the most common form of ovarian tumor in children and adolescents. These tumors are mostly benign and non-secreting. Virilization from an ovarian teratoma is exceptionally rare in pediatrics. Equally rare is the association of ovarian teratomas with auto-immune encephalitis. METHODS: We describe the case of a 15-year-old girl with menstrual abnormalities and virilization, who had a past medical history of encephalitis of an unknown etiology 16 months prior to presentation. RESULTS: Endocrine evaluation revealed an elevated serum testosterone and 17-hydroxy progesterone. A large left ovarian tumor was seen on a CT scan. Surgical excision revealed a mature cystic teratoma containing 6 liters of clear fluid with high androgen levels. Antibodies to the N-methyl-D-aspartate receptor of the hippocampus were detected in pre-operatively archived serum, but undetectable 6 months postoperatively. Immunohistochemistry studies on the tumor sections revealed that the antibodies in the patient's serum reacted with areas of the tumor expressing the N-methyl-D-aspartate receptor. Postoperatively, the patient's menstrual cycles became regular and her behavioral problems resolved. Her testosterone levels fell precipitously as well. CONCLUSION: Both virilizing mature cystic teratomas and teratoma-associated encephalitis are extremely rare in the pediatric population. We report on the first instance of these 2 rare entities occurring in the same patient.
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Doenças Autoimunes/complicações , Encefalite/complicações , Neoplasias Ovarianas/complicações , Teratoma/complicações , Virilismo/complicações , Adolescente , Agressão/psicologia , Androgênios/sangue , Autoanticorpos/sangue , Autoanticorpos/metabolismo , Progressão da Doença , Encefalite/imunologia , Feminino , Humanos , Imuno-Histoquímica , Leucocitose/líquido cefalorraquidiano , Proteínas Associadas aos Microtúbulos/metabolismo , Neoplasias Ovarianas/imunologia , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Receptores de N-Metil-D-Aspartato/imunologia , Teratoma/imunologia , Teratoma/metabolismo , Teratoma/patologiaRESUMO
The dynamics of loops at the DNA denaturation transition is studied. A scaling argument is used to evaluate the asymptotic behavior of the autocorrelation function of the state of complementary bases (either open or closed). The long-time asymptotic behavior of the autocorrelation function is expressed in terms of the entropy exponent, c, of a loop. The validity of the scaling argument is tested using a microscopic model of an isolated loop and a toy model of interacting loops. This suggests a method for measuring the entropy exponent using single-molecule experiments such as fluorescence correlation spectroscopy.
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PurposeTo evaluate the time course of changes in the thickness of retinal layers after epiretinal membrane (ERM) removal surgery.MethodsA retrospective cohort study of patients following surgery for idiopathic ERM. We used new specialized image analysis software to create a thickness map of each retinal layer and analyzed changes during one year follow-up. Healthy fellow eyes were used as negative controls and the retina prior to surgery as positive control.ResultsTwenty-one patients were included with a mean age of 68±13 years. Central macular thickness decreased steadily until 6 months after surgery (25% decrease, 516±76 to 386±73 µm, P<0.001) with no further decrease between 6 and 12 months (386±73 to 390±73 µm, P=0.291). The retinal nerve fiber layer (RNFL), and the ganglion cell and inner plexiform layer (GCIPL) were most affected (57%, P<0.001 and 27%, P=0.010, respectively). The thickest region showed a more abrupt decrease of 21% at first follow-up (504±61 to 399±58 µm, P=0.001) with subsequent decrements of about 3%. Prior to surgery all retinal layers were thicker in study eyes compared with healthy control eyes (6-63%, all P<0.05).ConclusionsFollowing ERM surgery, in the course of 6 months, the macula gradually becomes thinner after which a stable state is reached. All layers appear to be affected, with the RNFL and GCIPL impacted the most. Our results provide a unique view on how the thickness of different retinal layers changes following ERM surgery.
Assuntos
Membrana Epirretiniana/cirurgia , Retina/patologia , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Membrana Epirretiniana/patologia , Feminino , Humanos , Macula Lutea/patologia , Masculino , Pessoa de Meia-Idade , Fibras Nervosas/patologia , Células Ganglionares da Retina/patologia , Estudos Retrospectivos , Tomografia de Coerência Óptica/métodos , Acuidade VisualRESUMO
Unusual phases and phase transitions are seen at the magnetic-nonmagnetic boundary in Ce-, Eu- and Yb-based compounds. EuNi2P2 is a very unusual valence fluctuating Eu system, because at low temperatures the Eu valence stays close to 2.5 instead of approaching an integer value. The Eu valence, and thus the magnetic property in this system, can be tuned by Ge substitution in the P site as EuNi2Ge2 is known to exhibit the antiferromagnetc (AFM) ordering of divalent Eu moments with T(N)=30K. We have grown EuNi2(P(1-x)Ge(x))2 (0.0≤ x ≤0.5)) single crystals and studied their magnetic, thermodynamic and transport properties. Increasing Ge doping to x > 0.4 results in a well-defined AFM ordered state with T(N)=12K for x = 0.5. Moreover, the reduced value of magnetic entropy for x = 0.5 at T(N) suggests the presence of valance fluctuation/the Kondo effect in this compound. Interestingly, the specific heat exhibits an enhanced Sommerfeld coefficient upon Ge doping. Subsequently, electronic structure calculations lead to a non-integral valence in EuNi2P2 but a stable divalent Eu state in EuNi2Ge2, which is in good agreement with the experimental results.
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Dietary calcium and dietary phosphorus restriction were studied in chicks fed either cholecalciferol or 1alpha-hydroxycholecalciferol. Intestinal calcium absorption and calcium-binding protein of 1alpha-hydroxycholecalciferol-treated chicks remained unchanged under dietary calcium restriction, but increased under dietary phosphorus restriction. Kidney calcium-binding protein was not altered by dietary caclium restriction in chidks treated with either cholecalciferol or 1alpha-hydroxycholecalciferol, but increased under dietary phosphorus restriction independent of the vitamin D source. In contrast to the intestine, calcium-binding activity of the kidney was found to be poorly related to the calcium-binding protein concentration. It is suggested that kidney calcium-binding protein is regulated by a mechanism different from that of intestinal calcium-binding protein, and that its concentration in renal tissue is related to renal caclium excretion or plasma calcium level.
Assuntos
Cálcio/metabolismo , Rim/metabolismo , Vitamina D/metabolismo , Animais , Cálcio/farmacologia , Cálcio da Dieta , Galinhas , Colecalciferol/metabolismo , Hidroxicolecalciferóis/metabolismo , Rim/efeitos dos fármacos , Masculino , Fosfatos/farmacologia , Receptores de Droga/efeitos dos fármacosRESUMO
Radioactively labelled cholecalciferol was administered continuously to chicks that were fed normal, low-calcium and low-phosphorus diets. It has been possible to show that under such steady state conditions with regard to cholecalciferol, and mineral restriction, the animal reacts by increased accumulation of 1, 25-dihydroxycholecalciferol in the intestinal and the kidney cell, which was associated in the intestine with an increased calcium-binding activity. A similar accumulation of 1, 25-dihydroxycholecalciferol in bone was not noticed. It is proposed that the intestine and the kidney, but not bone, are the main target organs for cholecalciferol in the maintenance of calcium homeostasis, and that both calcium and phosphorus play a role in the regulation of the formation and subsequent function of 1, 25-dihydroxycholecalciferol.
Assuntos
Cálcio/deficiência , Colecalciferol/metabolismo , Fósforo/deficiência , Animais , Osso e Ossos/metabolismo , Cálcio/fisiologia , Núcleo Celular/metabolismo , Galinhas , Deficiências Nutricionais/metabolismo , Di-Hidroxicolecalciferóis/metabolismo , Mucosa Intestinal/metabolismo , Rim/metabolismo , Minerais/metabolismo , Especificidade de Órgãos , Fósforo/fisiologiaRESUMO
Male chicks, fed low, normal, or high calcium- and cholecalciferol-containing diets for 14 days, were given three combined injections of 17 beta-estradiol and testosterone (7 and 2.4 mg/kg/dose, respectively) or the vehicle alone, at 3-day intervals. The hormonal treatment resulted in increased plasma calcium and medullary bone calcium concentrations, independently of the dietary calcium intake. Kidney 25-hydroxycholecalciferol-1-hydroxylase and duodenal calcium-binding protein were increased in response to gonadal hormones. The magnitude of this response markedly diminished with increased calcium intake and almost completely disappeared in chicks fed the high calcium diet. The results suggest that the increases in plasma calcium and medullary bone formation due to gonadal hormones are independent of calcium intake while the effect of hormones on duodenal calcium-binding protein and the 25-hydroxycholecalciferol-1-hydroxylase activity appears to be mediated through the change in calcium needs due to medullary bone formation.
Assuntos
Cálcio da Dieta/metabolismo , Cálcio/sangue , Proteínas de Transporte/metabolismo , Estradiol/farmacologia , Proteína G de Ligação ao Cálcio S100/metabolismo , Testosterona/farmacologia , 25-Hidroxivitamina D3 1-alfa-Hidroxilase/metabolismo , Animais , Osso e Ossos/enzimologia , Duodeno/metabolismo , Rim/enzimologia , MasculinoRESUMO
Regulation of prepro-PTH and vitamin D receptor (VDR) mRNAs in the parathyroid glands was studied in chickens in vivo. The birds were raised to 21 days of age on a vitamin D-deficient diet with 1% calcium and 0.65% phosphorous. At the end of this period, the chicks exhibited marked hypocalcemia and enlarged parathyroid glands. In three separate trials, the birds were repleted for 6 days with vitamin D and different dietary calcium and phosphate concentrations, with 2 micrograms/kg 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] and different dietary calcium concentrations (0.5%, 1.0%, or 1.8%), or with 2 or 10 micrograms/kg 1,25-(OH)2D3 and 0.6% or 1.9% calcium or were kept vitamin D3 deficient and fed 0.5%, 1.0%, or 1.8% dietary calcium. Vitamin D treatment when combined with a high level of dietary calcium resulted in an increase in plasma calcium from 6 mg/dl to greater than 10 mg/dl, a decrease in PTH mRNA of 65%, and a 6- to 8-fold increase in VDR mRNA. In another experiment in which no vitamin D source was given and the diets contained increasing levels of dietary calcium, plasma calcium increased significantly (5.5 vs. 7 mg/dl), while PTH mRNA decreased by 40% and VDR mRNA increased by 60%. Neither parathyroid gland weight nor total RNA was significantly affected. When chicks were repleted with 1,25-(OH)2D3, the increase in plasma calcium and VDR mRNA and the decrease in PTH mRNA were considerably more pronounced than those in the absence of the vitamin D source. Furthermore, in the presence of the hormone, parathyroid weight and total RNA decreased significantly with increasing concentrations of dietary calcium. When the chicks were repleted, respectively, with the two levels of 1,25-(OH)2D3, a marked positive interaction was evident between the hormone and dietary calcium in affecting levels of PTH and VDR mRNA. These results suggest that both 1,25-(OH)2D3 and calcium participate in the regulation of PTH and VDR gene transcription in the avian parathyroid gland. Whereas the action of 1,25-(OH)2D3 requires a minimal level of dietary calcium, calcium affects PTH and VDR gene transcription even in the absence of any vitamin D source.
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Calcitriol/fisiologia , Cálcio/fisiologia , Glândulas Paratireoides/metabolismo , Hormônio Paratireóideo/genética , Precursores de Proteínas/genética , RNA Mensageiro/metabolismo , Animais , Cálcio/sangue , Cálcio da Dieta/farmacologia , Galinhas/metabolismo , Masculino , Receptores de Calcitriol , Receptores de Esteroides/genética , Deficiência de Vitamina D/sangueRESUMO
Expression of the osteopontin (OPN) gene in the oviduct of the laying hen was studied. It was detected only in the egg shell gland (ESG), where massive calcification occurs. No OPN gene expression was detected in any other part of the oviduct, such as the magnum and isthmus. The OPN gene was expressed in a circadian fashion during the daily egg cycle only during the period of egg shell calcification. No OPN gene expression was detected in the ESG of a pre-laying hen before the onset of reproduction, or after forced removal of the egg close to its entrance into the ESG. OPN was found to be synthesized by the epithelial cells of the ESG lining the lumen. Upon synthesis, OPN is immediately secreted out of cells and accumulates in the egg shell. These findings demonstrate for the first time temporal and spatial association of OPN with egg shell calcification. OPN, which was found to be part of the organic matrix of the egg shell, may play an important role in egg shell calcification.
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Galinhas/metabolismo , Casca de Ovo/metabolismo , Sialoglicoproteínas/fisiologia , Animais , Calcificação Fisiológica/genética , Galinhas/genética , DNA Complementar/genética , Escherichia coli/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Hibridização In Situ , Osteopontina , Oviductos/fisiologia , Proteínas Recombinantes de Fusão/biossíntese , Sialoglicoproteínas/biossíntese , Sialoglicoproteínas/genéticaRESUMO
The aim of this study is to evaluate the regulation of the osteopontin (OPN) gene expression by non-hormonal stimuli, such as calcium flux and mechanical strain during the daily egg cycle in the oviduct of the laying hen. After the egg enters the eggshell gland (ESG), the OPN gene is expressed by the epithelium cells in two waves: first by the basal cells and only then by the apical cells of the epithelium. A reduction in OPN gene expression was observed 1 h prior to laying. The calbindin gene, which marks the onset of calcification, was found to be expressed in the glandular epithelium starting 2 h after OPN gene expression. In addition, the formation of soft shells was accompanied by a reduction in calbindin, but not in OPN, gene expression. The application of a mechanical strain comparable to that induced by an egg led to induction of OPN gene expression at a normally quiescent phase in the cyclical expression of this gene. The induction of the gene was time- and strain-dependent and temporally similar to that induced by the entry of the egg into the ESG. In contrast, the calbindin gene was not affected by mechanical strain. The ESG of the laying hen provides a system to study the effect of a mechanical strain on matrix protein production in vivo, in a relevant physiological setting. The finding suggests that, in contrast to calbindin, OPN gene expression is not regulated by calcium flux but rather by the mechanical strain imposed by the resident egg.
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Sialoglicoproteínas/genética , Animais , Calbindinas , Galinhas , Casca de Ovo/metabolismo , Casca de Ovo/fisiologia , Feminino , Regulação da Expressão Gênica , Osteopontina , Estimulação Física , Proteína G de Ligação ao Cálcio S100/genéticaRESUMO
A new fast myosin heavy chain isoform was electrophoretically detected in adult rat skeletal muscles. It was present at high levels in diaphragm and, therefore, designated as MHCIId. Appreciable amounts of MHCIId were detected in tongue musculature, the extraocular muscles, and in the deep red portions of various fast muscles. Its concentration in fast-twitch muscle was greatly increased by chronic stimulation.
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Músculos/análise , Miosinas/análise , Animais , Diafragma/análise , Eletroforese em Gel de Poliacrilamida , Ratos , Ratos EndogâmicosRESUMO
The contents of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in plasma and intestinal mucose were increased by dietary calcium and by dietary phosphorus restriction. The concentration of intestinal occupied receptors for 1,25(OH)2D3 was higher in calcium-restricted birds. The affinity (association constant) of intestinal receptors for 1,25(OH)2D3 was lower in phosphorus-restricted chicks, as compared to control or calcium-restricted chicks. The number of binding sites were not influenced by dietary calcium or phosphorus restriction.
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Cálcio/deficiência , Mucosa Intestinal/metabolismo , Fósforo/deficiência , Receptores de Esteroides/metabolismo , Animais , Cálcio/sangue , Galinhas , Masculino , Fosfatos/sangue , Receptores de CalcitriolRESUMO
The effect of shell calcification and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on calbindin-D28K (previously known as vitamin D-dependent calcium-binding protein) and calbindin mRNA was investigated in the intestine and eggshell gland (ESG) of juvenile female chicks, laying hens and non-laying female birds with active gonads. Increasing amounts of 1,25-(OH)2D3 were fed to laying hens and juvenile birds treated with oestradiol to develop the ESG. The intestinal concentration of calbindin was increased 30-fold by 1,25-(OH)2D3 in chicks treated with oestradiol and fed a vitamin D-deficient diet. In these same animals, 1,25-(OH)2D3 had no effect on the formation of calbindin mRNA or calbindin in the ESG even though fully viable 1,25-(OH)2D3 receptors are present in this tissue. In laying birds fed adequate amounts of vitamin D3, intestinal, but not ESG, calbindin was increased by the addition of 1,25-(OH)2D3 to the diet. At the onset of egg production the concentrations of calbindin and calbindin mRNA were increased in the intestine and ESG. This increase occurred within the period of calcification of the first egg, through a process unaffected by vitamin D. Calcification of the first egg increased the concentration of calbindin in the ESG by eight- to tenfold, although the concentration of calbindin mRNA was increased by only two- to threefold. These results suggest that the induction of calbindin synthesis by 1,25-(OH)2D3 or by the egg calcification process is associated with an increase in the concentration of calbindin mRNA in the ESG and intestine.(ABSTRACT TRUNCATED AT 250 WORDS)
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Casca de Ovo/metabolismo , Glândulas Exócrinas/metabolismo , Mucosa Intestinal/metabolismo , RNA Mensageiro/biossíntese , Proteína G de Ligação ao Cálcio S100/genética , Animais , Calbindinas , Calcificação Fisiológica , Calcitriol/farmacologia , Galinhas , Estradiol/farmacologia , Feminino , Óvulo/metabolismo , Proteína G de Ligação ao Cálcio S100/biossínteseRESUMO
The binding of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) to its intestinal receptor was studied in chicks fed a phosphorus (P)-deficient diet. The equilibrium association constant (Ka) was determined by Scatchard analysis. Association (Kass) and dissociation (Kdis) rate constants were determined in experiments on hormone uptake and release respectively. The Ka, determined at 4, 12 and 19 degrees C, decreased progressively during P deficiency, due to the decrease in Kass, but Kdis was not affected. During prolonged P deficiency the concentration of binding sites (Nmax) also decreased. Duodenal calcium-binding protein (CaBP) increased during 10 days of P deficiency and then decreased. The long-term decrease in receptor affinity and Nmax may account for the observed reduction in receptor occupancy and the decrease in the high level of intestinal CaBP stimulated during early P deficiency. The resulting decrease in Ca absorption may minimize the hypercalcaemia induced by the deficiency.
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Calcitriol/metabolismo , Duodeno/metabolismo , Fósforo/deficiência , Receptores de Esteroides/metabolismo , Animais , Sítios de Ligação , Cálcio/deficiência , Galinhas , Dieta , Mucosa Intestinal/metabolismo , Cinética , Masculino , Receptores de CalcitriolRESUMO
The effects of vitamin D3 sources, egg production and egg cycle on the genomic expression of calbindin (Mr 28,000) in the intestine and egg shell gland (ESG) of quail were characterized by Northern blot and solution hybridization, using synthetic oligonucleotide probe. In vitamin D3- or 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3)-fed quail, onset of egg production induced duodenal and ESG calbindin mRNA and calbindin synthesis. Duodenal calbindin mRNA was slightly higher during the period of shell calcification as compared with the period during which shells were not formed (ESG inactivity). ESG calbindin mRNA was markedly higher during the period of shell calcification than of ESG inactivity. Increasing dietary intake of [3H]1 alpha-hydroxyvitamin D3 increased the duodenal, but not ESG, content of 1,25-(OH)2D3 and calbindin. Duodenal calbindin and its mRNA were absent in vitamin D-deficient quail and were not affected by egg laying. ESG calbindin in the vitamin D-deficient quail was not affected by egg laying, but calbindin mRNA increased in the vitamin D-deficient birds during shell calcification. The results suggest that: (a) intestinal calbindin mRNA and calbindin are induced and/or regulated, either directly or indirectly, by 1,25-(OH)2D3; (b) intestinal calbindin and its mRNA are further induced at the onset of egg laying by an additional stimulator besides 1,25-(OH)2D3; (c) 1,25-(OH)2D3 is required for the expression of the latter stimulator; (d) ESG calbindin mRNA and calbindin are induced in egg-laying birds by a stimulator associated with the egg cycle; and (e) the induction of ESG calbindin mRNA does not need vitamin D metabolites, but 1,25-(OH)2D3 is required for the translation of the mRNA.
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Calcitriol/farmacologia , Colecalciferol/farmacologia , Duodeno/metabolismo , Oviductos/metabolismo , Oviposição/fisiologia , Codorniz/metabolismo , Proteína G de Ligação ao Cálcio S100/biossíntese , Animais , Calbindinas , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , RNA Mensageiro/biossíntese , Proteína G de Ligação ao Cálcio S100/genética , Deficiência de Vitamina D/metabolismoRESUMO
Synthetic oligonucleotide probes complementary to chick calbindin-28 kDa-mRNA were used to study the latter's regulation and relationship to calbindin in the chick. The effects of vitamin D3 sources and dietary alteration on the genomic expression were characterized by Northern blot and solution hybridization. Intestinal calbindin and its mRNA were almost absent in vitamin D-deficient chicks and were not affected by dietary alteration. Renal calbindin and its mRNA were lower in the vitamin D-deficient than in vitamin D3- or 1,25-dihydroxyvitamin D3 (1,25(OH)2D3)-fed chicks. In the same animal, renal calbindin mRNA and calbindin were higher than intestinal. In vitamin D3-fed chicks, dietary calcium (Ca) or phosphorus (P) restriction induced, and high dietary Ca inhibited, intestinal calbindin and its mRNA synthesis. In the same chicks, dietary P restriction induced renal calbindin mRNA and calbindin synthesis. In 1,25-(OH)2D3-fed chicks, dietary P restriction induced and high dietary Ca inhibited the synthesis of intestinal and renal calbindin. The results suggest that: (a) most of the changes in renal and intestinal calbindin could be attributed to the changes in the mRNA; (b) the adaptation to dietary Ca and P alterations requires vitamin D metabolites; (c) high dietary Ca affects intestinal and renal calbindin-mRNA and calbindin via mechanisms independent of kidney 1-hydroxylase; and (d) plasma Ca and renal calbindin or its mRNA tend to change together in vitamin D-deficient or vitamin D3-fed, but not in 1,25(OH)2D3-fed chicks.