RESUMO
In skeletal muscle (SM), inward Ca2+-currents have no apparent role in excitation-contraction coupling (e-c coupling), however the Ca2+-channel blocker can affect twitch and tetanic muscle in mammalian SM. Experiments were conducted to study how diltiazem (DLZ) facilitates e-c coupling and inhibits contraction. 1) In complete Extensor Digitorum Longus (EDL) muscle and single intact fibres, 0.03 mM DLZ causes twitch potentiation and decreases force during tetanic activity, with increased fatigue. 2) In split open fibres isolated from EDL fibres, DLZ inhibits sarcoplasmic reticulum (SR) Ca2+-loading in a dose-dependent manner and has a potentiating effect on caffeine-induced SR Ca2+-release. 3) In isolated light SR (LSR) vesicles, SERCA1 hydrolytic activity is not affected by DLZ up to 0.2 mM. However, ATP-dependent Ca2+-uptake was inhibited in a dose-dependent manner at a concentration where e-c coupling is changed. 4) The passive Ca2+-efflux from LSR was reduced by half with 0.03 mM diltiazem, indicating that SR leaking does not account for the decreased Ca2+-uptake. 5) The denaturation profile of the SERCA Ca2+-binding domain has lower thermal stability in the presence of DLZ in a concentration-dependent manner, having no effect on the nucleotide-binding domain. We conclude that the effect of DLZ on SM is exerted by crossing the sarcolemma and interacting directly with the SERCA Ca2+-binding domain, affecting SR Ca2+-loading during relaxation, which has a consequence on SM contractility. Diltiazem effect on SM could be utilized as a tool to understand SM e-c coupling and muscle fatigue.
Assuntos
Diltiazem , Músculo Esquelético , Animais , Diltiazem/farmacologia , Retículo Sarcoplasmático , Fadiga Muscular , Cafeína/farmacologia , Mamíferos , Contração Muscular , Cálcio/farmacologiaRESUMO
OBJECTIVES: This in situ study aimed to assess the remineralizing effect of a fluoride toothpaste supplemented with ß-calcium glycerophosphate in both micro (ß-CaGPm) and nano-sized forms (ß-CaGPn). METHODS: This blind and cross-over study was performed in 4 phases, each spanning 3 days. Twelve volunteers utilized palatal appliances containing four bovine enamel blocks with artificial caries lesions. Volunteers were randomly assigned to the following treatment groups: Placebo (no F-ß-CaGPm-ß-CaGPn); 1100 ppm F alone (1100F); 1100F plus 0.5% micrometric ß-CaGP (1100F-0.5%ß-CaGPm); and 1100F plus 0.25%nano-sized ß-CaGP (1100F-0.25%ß-CaGPn). Participants were instructed to brush their natural teeth with the palatal appliances in the mouth for 1 min (3 times/day), ensuring that the enamel blocks were exposed to the natural toothpaste slurries. Following each phase, evaluations were conducted to determine the percentage of surface hardness recovery (%SHR), integrated recovery of subsurface hardness (ΔIHR), profile subsurface lesion through polarized light microscopy (PLM), as well as fluoride (F), calcium (Ca), and phosphorus (P) concentrations within the enamel. Data were analyzed by ANOVA and Student-Newman-Keuls test (p < 0.001). RESULTS: Treatment with 1100F-0.25%ß-CaGPn resulted in %SHR â¼69 % and â¼40 % higher when compared to 1100F and 1100F-0.5%ß-CaGPm (p < 0.001). The reduction in lesion body (ΔIHR; PLM) was â¼40 % higher with 1100F-0.25%ß-CaGPn (p < 0.001) compared to 1100F. The addition of ß-CaGPm and ß-CaGPn did not influence enamel F concentration (p > 0.001). Treatment with 1100F-0.25%ß-CaGPn led to an increase in the concentration of Ca and P in the enamel (p < 0.001). CONCLUSION: The addition of 0.25%ß-CaGPn into 1100F formulation increased the bioavailability of calcium and phosphate, promoting a higher remineralizing effect. CLINICAL SIGNIFICANCE: Toothpaste containing 1100F-0.25%ß-CaGPn showed a potential of higher remineralization to 1100 ppm F and 1100 ppm F micrometric ß-CaGP could be a strategy for patients at caries activity.
Assuntos
Fluoretos , Cremes Dentais , Animais , Bovinos , Humanos , Cálcio/farmacologia , Cariostáticos/farmacologia , Estudos Cross-Over , Esmalte Dentário , Fluoretos/farmacologia , Glicerofosfatos/farmacologia , Dureza , Remineralização Dentária/métodos , Cremes Dentais/farmacologia , Cremes Dentais/uso terapêuticoRESUMO
Dilated cardiomyopathy (DCM) is a primary myocardial disease, leading to heart failure and excessive risk of sudden cardiac death with rather poorly understood pathophysiology. In 2015, Parvari's group identified a recessive mutation in the autophagy regulator, PLEKHM2 gene, in a family with severe recessive DCM and left ventricular non-compaction (LVNC). Fibroblasts isolated from these patients exhibited abnormal subcellular distribution of endosomes, Golgi apparatus, lysosomes and had impaired autophagy flux. To better understand the effect of mutated PLEKHM2 on cardiac tissue, we generated and characterized induced pluripotent stem cells-derived cardiomyocytes (iPSC-CMs) from two patients and a healthy control from the same family. The patient iPSC-CMs showed low expression levels of genes encoding for contractile functional proteins (α and ß-myosin heavy chains and 2v and 2a-myosin light chains), structural proteins integral to heart contraction (Troponin C, T and I) and proteins participating in Ca2+ pumping action (SERCA2 and Calsequestrin 2) compared to their levels in control iPSC-derived CMs. Furthermore, the sarcomeres of the patient iPSC-CMs were less oriented and aligned compared to control cells and generated slowly beating foci with lower intracellular calcium amplitude and abnormal calcium transient kinetics, measured by IonOptix system and MuscleMotion software. Autophagy in patient's iPSC-CMs was impaired as determined from a decrease in the accumulation of autophagosomes in response to chloroquine and rapamycin treatment, compared to control iPSC-CMs. Impairment in autophagy together with the deficiency in the expression of NKX2.5, MHC, MLC, Troponins and CASQ2 genes, which are related to contraction-relaxation coupling and intracellular Ca2+ signaling, may contribute to the defective function of the patient CMs and possibly affect cell maturation and cardiac failure with time.
Assuntos
Cardiomiopatia Dilatada , Células-Tronco Pluripotentes Induzidas , Humanos , Cálcio/metabolismo , Cálcio/farmacologia , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/metabolismo , Diferenciação Celular , Mutação , Miócitos Cardíacos/metabolismoRESUMO
Esquamosan, a new furofuran lignan, has been isolated by bio-guided assays from the methanolic extract of the leaves of Annona squamosa L., and its structure was elucidated by spectroscopic methods. Esquamosan inhibited the rat aortic ring contraction evoked by phenylephrine in a concentration-dependent manner and showed an inhibitory effect on vasocontraction of the depolarized aorta with high-concentration potassium. The vasorelaxant effect by esquamosan could be attributed mainly to the inhibition of calcium influx from extracellular space through voltage-dependent calcium channels or receptor-operated Ca2+ channels and also partly mediated through the increased release of NO from endothelial cells. The ability of esquamosan to modify the vascular reactivity of rat aortic rings incubated with high glucose (D-glucose 55 mM) was then evaluated, and this furofuran lignan reverted the endothelium-dependent impairment effect of high glucose in rat aortic rings. The antioxidant capacity of esquamosan was assessed using DPPH and FRAP assays. Esquamosan exhibited a similar antioxidant capacity compared to ascorbic acid, which was used as a positive control. In conclusion, this lignan showed a vasorelaxant effect, free radical scavenging capacity, and potential reductive power, suggesting its potential beneficial use to treat complex cardiometabolic diseases due to free radical-mediated diseases and its calcium antagonist effect.
Assuntos
Annona , Annonaceae , Lignanas , Ratos , Animais , Vasodilatadores/farmacologia , Lignanas/farmacologia , Antioxidantes/farmacologia , Cálcio/farmacologia , Células Endoteliais , Aorta Torácica , Vasodilatação , Endotélio VascularRESUMO
OBJECTIVE: Regular use of toothpaste with fluoride (F) concentrations of ≥ 1000 ppm has been shown to contribute to reducing caries increment. However, when used by children during the period of dental development, it can lead to dental fluorosis. In this study, we aimed to evaluate the in vitro effect of a toothpaste formulation with reduced fluoride (F) concentration (200 ppm) supplemented with sodium trimetaphosphate (TMP: 0.2%), Xylitol (X:16%), and Erythritol (E: 4%) on dental enamel demineralization. METHODOLOGY: Bovine enamel blocks were selected according to initial surface hardness (SHi) and then divided into seven experimental toothpaste groups (n=12). These groups included 1) no F-TMP-X-E (Placebo); 2) 16% Xylitol and 4% Erythritol (X-E); 3) 16% Xylitol, 4% Erythritol and 0.2%TMP (X-E-TMP); 4) 200 ppm F (no X-E-TMP: (200F)); 5) 200 ppm F and 0.2% TMP (200F-TMP); 200 ppm F, 16% Xylitol, 4% Erythritol, and 0.2% TMP (200F-X-E-TMP); and 7) 1,100 ppm F (1100F). Blocks were individually treated 2×/day with slurries of toothpastes and subjected to a pH cycling regimen for five days (DES: 6 hours and RE: 18 hours). Then, the percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), fluoride (F), calcium (Ca), and phosphorus (P) in enamel were determined. The data were analyzed by ANOVA (1-criterion) and the Student-Newman-Keuls test (p<0.001). RESULTS: We found that the 200F-X-E-TMP treatment reduced %SH by 43% compared to the 1100F treatments (p<0.001). The ΔKHN was ~ 65% higher with 200F-X-E-TMP compared to 1100F (p<0.001). The highest concentration of F in enamel was observed on the 1100F treatment (p<0.001). The 200F-X-E-TMP treatment promote higher increase of Ca and P concentration in the enamel (p<0.001). CONCLUSION: The association of 200F-X-E-TMP led to a significant increase of the protective effect on enamel demineralization compared to the 1100F toothpaste.
Assuntos
Fluoretos , Desmineralização do Dente , Criança , Animais , Bovinos , Humanos , Fluoretos/farmacologia , Cremes Dentais/uso terapêutico , Xilitol/farmacologia , Xilitol/uso terapêutico , Desmineralização do Dente/tratamento farmacológico , Esmalte Dentário , Dureza , Cálcio/farmacologia , Cariostáticos/farmacologia , Fluoreto de Sódio/farmacologiaRESUMO
Developing dental materials for the prevention of remineralization or demineralization is important for high-risk caries patients. This study aimed to evaluate the physicochemical and microbiological effects of adding 45S5 bioglass to resin-modified glass ionomer cement (RMGIC). Samples belonged to the following groups: GIC: conventional glass ionomer cement (Vitro Fil), RMGIC: resin-modified GIC (Vitro Fil LC), and RMGIC/45S5: RMGIC with 10% (wt %) of 45S5. Changes in pH and release of fluoride, calcium, and phosphorus ions under acidic (pH 4) and neutral (pH 7) pH conditions were evaluated. Antibacterial activity was verified based on colony-forming units. Material sorption and solubility were analyzed after bacterial exposure. After 28 days, the bioactivity of the materials was evaluated using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Analysis of variance, post hoc Scheffe, and Tukey (α = 0.05) tests were employed for statistical analysis. RMGIC/45S5 showed higher alkalization activity, calcium release at pH 4 and 7, and sorption than GIC and RMGIC (p < .05). Release of phosphorus and fluoride at pH 4 and 7 was higher for GIC than that for RMGIC and RMGIC/45S5 (p < .05). RMGIC/45S5 showed higher values than RMGIC (p < .05). However, antibacterial activity did not differ among the groups. Precipitates of calcium and phosphorus were visualized in RMGIC/45S5 samples via SEM/EDS. These results indicate that the RMGIC/45S5 promotes alkalization and increases the release of calcium, phosphorus, and fluoride ions, resulting in precipitate deposition rich in calcium and phosphorus, thereby being a promising option to improve the bioactivity of RMGIC.
Assuntos
Cálcio , Fluoretos , Humanos , Fluoretos/farmacologia , Fluoretos/química , Cálcio/farmacologia , Cálcio/análise , Teste de Materiais , Antibacterianos/farmacologia , Fósforo/farmacologia , Cimentos de Ionômeros de Vidro/farmacologia , Cimentos de Ionômeros de Vidro/químicaRESUMO
The continued increase of the demand for seed of the Pacific oyster (Crassostrea gigas) has driven the aquaculture industry to produce land-based hatcheries using broodstock conditioning. This has led to the need to create closed systems to control the main factors involved in reproduction (temperature and food). Additionally, reproductive synchronization of broodstocks may be considered to ensure homogeneous maturation and spawning among the organisms. In this work, we synchronized the broodstock reproductive stage of Pacific oysters in a recirculating aquaculture system (RAS) using a "preconditioning" process and evaluated the effect of the water quality and the CO2-carbonate system on preconditioned broodstock. The oysters were kept at 12 °C for 45 days in a RAS containing a calcium reactor (C2) or without a calcium reactor (C1, control). Water quality parameters were measured daily, and the oyster's condition and reproductive development were monitored using condition index, biometrics, and histology, on Days 0, 20, and 45. C1 and C2 systems kept the water quality within the ranges reported as favorable for bivalves. The calcium reactor kept the pH (8.03-8.10), alkalinity (200 mg/L as CaCO3), CO32- (≤ 80 µmol/kg), and Ω aragonite (≤ 1) closer to the ranges reported as optimal for bivalves. However, no significant differences were detected in the total weight and the condition index in C1 and C2. The preconditioning allowed to maintain the organisms in early reproductive development, allowing gametogenesis synchronization to start maturation.
Assuntos
Crassostrea , Animais , Dióxido de Carbono/farmacologia , Cálcio/farmacologia , Qualidade da Água , Carbonatos/farmacologia , Aquicultura , Cálcio da Dieta/farmacologiaRESUMO
The effects of acute caffeine supplementation on muscular strength remain unclear. We examined the effects of two different doses of caffeine on muscle strength and calcium in plasma compared to placebo using a crossover, randomized, double-blind, placebo-controlled design. Twenty-one (n = 21) recreationally resistance-trained participants were randomly assigned into three experimental conditions: 6 mg·kg bw−1 of caffeine (CF6); 8 mg·kg bw−1 of caffeine (CF8); or placebo (PLA), with a 7-day washout period between conditions. Muscular strength assessments were made for both upper (bench press) and lower body muscles (squat and deadlift). Calcium release in plasma was measured on five different occasions. Bench press (CF8: 100.1 ± 1.9 kg; PLA: 94.2 ± 2.5 kg), deadlift (CF8: 132.8 ± 3.5 kg; PLA: 120.7 ± 5.7 kg), and squat (CF8: 130.1 ± 4.9 kg; PLA 119.4 ± 5.4 kg) strength were all significantly (p < 0.001) improved in CF8 compared to PLA. Calcium release in plasma was significantly increased in CF8, whereas no changes were observed in CF6 or PLA. Overall, 8 mg·kg bw−1 of caffeine appears to be an effective dose to optimize upper and lower body muscular strength and calcium release in recreationally trained participants.
Assuntos
Cafeína , Cálcio , Masculino , Humanos , Cafeína/farmacologia , Cálcio/farmacologia , Força Muscular , Cálcio da Dieta/farmacologia , Poliésteres/farmacologiaRESUMO
OBJECTIVES: To investigate the physical-chemical properties of home bleaching gels based on Carbamide Peroxide (CP) and Hydrogen Peroxide (HP) after accelerated stability (AS) and its effects on enamel. MATERIALS AND METHODS: A total of 360 bovine teeth blocks were divided (n = 12): Control, CP10%-Whiteness Perfect, CP10%-Pola Night, HP7.5%-Pola Day, and HP7.5%-White Class Calcium. Microhardness (KHN), roughness (Ra), color (ΔE and ΔE00), hardness, compressibility, elasticity, cohesiveness, adhesiveness, weight, pH, and calcium (Ca) quantification in enamel were analyzed without storage of the bleaching gels and after AS at 1 and 3 months. Data of Ca, KHN, and Ra were analyzed through mixed models for repeated measurements and the Tukey-Kramer test. Values of weight, hardness, compressibility, and elasticity were analyzed with two-way ANOVA and Tukey's test. ΔE/ΔE00 data, cohesiveness, and adhesiveness were analyzed with Kruskal-Wallis and Dunn tests (α = 0.05). RESULTS: Groups subject to AS had lower ΔE and ΔE00 compared to those without storage. Lower KHN and higher Ra values were found after bleaching treatment in all groups compared to controls. Higher amounts of Ca were found on the first day of evaluation in the gels subject to AS for 3 months, regardless of the bleaching agent used. CONCLUSIONS: Incorrectly stored bleaching gel accentuates adverse effects on enamel. Temperature and humidity interfere directly with the chemical stability of bleaching agents, reducing their properties. CLINICAL RELEVANCE: HP is an unstable oxidizing agent when stored at high temperatures. Therefore, pH becomes more acidic and potentiates the demineralizing effect on enamel.
Assuntos
Clareadores Dentários , Clareamento Dental , Bovinos , Animais , Clareamento Dental/efeitos adversos , Cálcio/farmacologia , Ureia/farmacologia , Esmalte Dentário , Dureza , Peróxido de Hidrogênio/farmacologia , Géis/farmacologia , Ácido Hipocloroso/farmacologia , Clareadores Dentários/farmacologia , Peróxidos/farmacologiaRESUMO
This study aimed at investigating the combined effect of biofilm accumulation and 20% sucrose rinse on the modulation of calcium (Ca2+), phosphate (Pi), and fluoride (F-) bioavailability in the saliva of children with early childhood caries (ECC). Fifty-six preschoolers of both genders were evaluated according to caries experience and activity: caries-free (CF, n = 28) and with ECC (n = 28) and then, submitted to biofilm intervention (biofilm accumulation). In each situation, saliva samples were collected before and five minutes after a 20% sucrose rinse to determine the concentrations of Ca2+, Pi, and F-. Calcium concentration was significantly lower in the biofilm accumulation situation compared to the situation of biofilm mechanical control (p ≤ 0.01), except for CF children after sucrose rinse. Biofilm accumulation increased salivary calcium concentration in children with ECC after sucrose rinse (p = 0.04), whereas mechanical biofilm control reduced it in both groups (p = 0.000). Phosphate concentration was influenced by mechanical control of biofilm in CF children (p = 0.03). The fluoride bioavailability was reduced by sucrose rinse and biofilm accumulation in CF and ECC children (p ≤ 0.002). In conclusion, the combined effect of biofilm accumulation and sucrose rinse modifies the bioavailability of calcium and fluoride in the saliva of children with early childhood caries.