Characterization of angiotensin-converting enzymes 1 and 2 in the soleus and plantaris muscles of rats

Angiotensin-converting enzymes 1 (ACE1) and 2 (ACE2) are key enzymes of the renin-angiotensin system, which act antagonistically to regulate the levels of angiotensin II (Ang II) and Ang-(1-7). Considerable data show that ACE1 acts on normal skeletal muscle functions and architecture. However, little is known about ACE1 levels in muscles with different fiber compositions. Furthermore, ACE2 levels in skeletal muscle are not known. Therefore, the purpose of this study was to characterize protein expression and ACE1 and ACE2 activities in the soleus and plantaris muscles. Eight-week-old female Wistar rats (N = 8) were killed by decapitation and the muscle tissues harvested for biochemical and molecular analyses. ACE1 and ACE2 activities were investigated by a fluorometric method using Abz-FRK(Dnp)P-OH and Mca-YVADAPK(Dnp)-OH fluorogenic substrates, respectively. ACE1 and ACE2 protein expression was analyzed by Western blot. ACE2 was expressed in the skeletal muscle of rats. There was no difference between the soleus (type I) and plantaris (type II) muscles in terms of ACE2 activity (17.35 ± 1.7 vs 15.09 ± 0.8 uF·min-1·mg-1, respectively) and protein expression. ACE1 activity was higher in the plantaris muscle than in the soleus (71.5 ± 3.9 vs 57.9 ± 1.1 uF·min-1·mg-1, respectively). Moreover, a comparative dose-response curve of protein expression was established in the soleus and plantaris muscles, which indicated higher ACE1 levels in the plantaris muscle. The present findings showed similar ACE2 levels in the soleus and plantaris muscles that might result in a similar Ang II response; however, lower ACE1 levels could attenuate Ang II production and reduce bradykinin degradation in the soleus muscle compared to the plantaris. These effects should enhance the aerobic capacity necessary for oxidative muscle activity.

5-HT1A autoreceptor modulation of locomotor activity induced by nitric oxide in the rat dorsal raphe nucleus

The dorsal raphe nucleus (DRN) is the origin of ascending serotonergic projections and is considered to be an important component of the brain circuit that mediates anxiety- and depression-related behaviors. A large fraction of DRN serotonin-positive neurons contain nitric oxide (NO). Disruption of NO-mediated neurotransmission in the DRN by NO synthase inhibitors produces anxiolytic- and antidepressant-like effects in rats and also induces nonspecific interference with locomotor activity. We investigated the involvement of the 5-HT1A autoreceptor in the locomotor effects induced by NO in the DRN of male Wistar rats (280-310 g, N = 9-10 per group). The NO donor 3-morpholinosylnomine hydrochloride (SIN-1, 150, and 300 nmol) and the NO scavenger S-3-carboxy-4-hydroxyphenylglycine (carboxy-PTIO, 0.1-3.0 nmol) were injected into the DRN of rats immediately before they were exposed to the open field for 10 min. To evaluate the involvement of the 5-HT1A receptor and the N-methyl-D-aspartate (NMDA) glutamate receptor in the locomotor effects of NO, animals were pretreated with the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 8 nmol), the 5-HT1A receptor antagonist N-(2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl)-N-2-pyridinyl-cyclohexanecarboxamide maleate (WAY-100635, 0.37 nmol), and the NMDA receptor antagonist DL-2-amino-7-phosphonoheptanoic acid (AP7, 1 nmol), followed by microinjection of SIN-1 into the DRN. SIN-1 increased the distance traveled (mean ± SEM) in the open-field test (4431 ± 306.1 cm; F7,63 = 2.44, P = 0.028) and this effect was blocked by previous 8-OH-DPAT (2885 ± 490.4 cm) or AP7 (3335 ± 283.5 cm) administration (P < 0.05, Duncan test). These results indicate that 5-HT1A receptor activation and/or facilitation of glutamate neurotransmission can modulate the locomotor effects induced by NO in the DRN.

Simultaneous allergen inactivation and detoxification of castor bean cake by treatment with calcium compounds

Ricinus communis L. is of great economic importance due to the oil extracted from its seeds. Castor oil has been used for pharmaceutical and industrial applications, as a lubricant or coating agent, as a component of plastic products, as a fungicide or in the synthesis of biodiesel fuels. After oil extraction, a castor cake with a large amount of protein is obtained. However, this by-product cannot be used as animal feed due to the presence of toxic (ricin) and allergenic (2S albumin) proteins. Here, we propose two processes for detoxification and allergen inactivation of the castor cake. In addition, we establish a biological test to detect ricin and validate these detoxification processes. In this test, Vero cells were treated with ricin, and cell death was assessed by cell counting and measurement of lactate dehydrogenase activity. The limit of detection of the Vero cell assay was 10 ng/mL using a concentration of 1.6 x 10(5) cells/well. Solid-state fermentation (SSF) and treatment with calcium compounds were used as cake detoxification processes. For SSF, Aspergillus niger was grown using a castor cake as a substrate, and this cake was analyzed after 24, 48, 72, and 96 h of SSF. Ricin was eliminated after 24 h of SSF treatment. The cake was treated with 4 or 8% Ca(OH)2 or CaO, and both the toxicity and the allergenic properties were entirely abolished. A by-product free of toxicity and allergens was obtained.

Serum 25-hydroxyvitamin D and biochemical markers of bone metabolism in patients with juvenile idiopathic arthritis

Our objective was to evaluate the concentrations of serum 25-hydroxyvitamin D [25(OH)D], serum calcium, serum phosphorus, alkaline phosphatase, and parathormone (PTH) in patients with polyarticular juvenile idiopathic arthritis (JIA) and to associate them with disease duration and activity, bone mineral density and use of medications. In a cross-sectional and controlled study, 30 patients with polyarticular JIA were evaluated and compared to 30 healthy individuals matched for age and gender. Clinical status, anthropometry, laboratory markers in both patients and controls, and bone mineral density, only in the patients, were measured. Of the 30 patients included in the study, 23 (76.7%) were female and 16 (53.3%) non-Caucasian; mean age was 14 years (range = 4 to 20 years). Mean disease duration was 5 years (range = 1 to 12 years). The mean concentrations of serum albumin-corrected calcium (9.04 ± 0.41 mg/dL) and alkaline phosphatase (153.3 ± 100.1 IU) were significantly lower in patients with JIA than in controls (P < 0.0001 and P = 0.001, respectively). No differences in 25(OH)D, PTH or serum phosphorus were observed between JIA and control subjects. Regarding 25(OH)D concentration, 8 patients (26.7%) and 5 controls (16.7%) had 25(OH)D concentrations compatible with deficiency (lower than 20 ng/mL) and 14 patients (46.7%) and 18 controls (60%) had concentrations compatible with insufficiency (20-32 ng/mL). These values were not associated with disease activity, use of medications or bone mineral density. We observed a high frequency of 25(OH)D insufficiency and deficiency in the study sample. The compromised bone metabolism emphasizes the importance of follow-up of JIA patients.

Effect of vitamin D therapy in addition to amitriptyline on migraine attacks in pediatric patients

The purpose of this study was to investigate the effect of supplementary vitamin D therapy in addition to amitriptyline on the frequency of migraine attacks in pediatric migraine patients. Fifty-three children 8-16 years of age and diagnosed with migraine following the International Headache Society 2005 definition, which includes childhood criteria, were enrolled. Patients were classified into four groups on the basis of their 25-hydroxyvitamin D [25(OH)D] levels. Group 1 had normal 25(OH)D levels and received amitriptyline therapy alone; group 2 had normal 25(OH)D levels and received vitamin D supplementation (400 IU/day) plus amitriptyline; group 3 had mildly deficient 25(OH)D levels and received amitriptyline plus vitamin D (800 IU/day); and group 4 had severely deficient 25(OH)D levels and was given amitriptyline plus vitamin D (5000 IU/day). All groups were monitored for 6 months, and the number of migraine attacks before and during treatment was determined. Calcium, phosphorus alkaline phosphatase, parathormone, and 25(OH)D levels were also determined before and during treatment. Results were compared between the groups. Data obtained from the groups were analyzed using one-way analysis of variance. The number of pretreatment attacks in groups 1 to 4 was 7±0.12, 6.8±0.2, 7.3±0.4, and 7.2±0.3 for 6 months, respectively (all P>0.05). The number of attacks during treatment was 3±0.25, 1.76±0.37 (P<0.05), 2.14±0.29 (P<0.05), and 1.15±0.15 (P<0.05), respectively. No statistically significant differences in calcium, phosphorus, alkaline phosphatase, or parathormone levels were observed (P>0.05). Vitamin D given in addition to anti-migraine treatment reduced the number of migraine attacks.

Low serum concentrations of 25-hydroxyvitamin D in children and adolescents with systemic lupus erythematosus

We evaluated the concentrations of 25-hydroxyvitamin D [25(OH)D] in children and adolescents with juvenile systemic lupus erythematosus (JSLE) and associated them with disease duration and activity, use of medication (chloroquine and glucocorticoids), vitamin D intake, calcium and alkaline phosphatase levels, and bone mineral density. Thirty patients with JSLE were evaluated and compared to 30 healthy individuals, who were age and gender matched. Assessment was performed of clinical status, disease activity, anthropometry, laboratory markers, and bone mineral density. The 30 patients included 25 (83.3%) females and 16 (53.3%) Caucasians, with a mean age of 13.7 years. The mean age at diagnosis was 10.5 years and mean disease duration was 3.4 years. Mean levels of calcium, albumin, and alkaline phosphatase were significantly lower in patients with JSLE compared with controls (P<0.001, P=0.006, and P<0.001, respectively). Twenty-nine patients (97%) and 23 controls (77%) had 25(OH)D concentrations lower than 32 ng/mL, with significant differences between them (P<0.001). Fifteen patients (50%) had vitamin D levels <20 ng/mL and 14 had vitamin D levels between 20 and 32 ng/mL. However, these values were not associated with greater disease activity, higher levels of parathormone, medication intake, or bone mineral density. Vitamin D concentrations were similar with regard to ethnic group, body mass index, height for age, and pubertal stage. Significantly more frequently than in controls, we observed insufficient serum concentrations of 25(OH)D in patients with JSLE; however, we did not observe any association with disease activity, higher levels of parathormone, lower levels of alkaline phosphatase, use of medications, or bone mineral density alterations.

Correlation, by multivariate statistical analysis, between the scavenging capacity against reactive oxygen species and the bioactive compounds from frozen fruit pulps

The contents of total phenolic compounds (TPC), total flavonoids (TF), and ascorbic acid (AA) of 18 frozen fruit pulps and their scavenging capacities against peroxyl radical (ROO•), hydrogen peroxide (H2O2), and hydroxyl radical (•OH) were determined. Principal Component Analysis (PCA) showed that TPC (total phenolic compounds) and AA (ascorbic acid) presented positive correlation with the scavenging capacity against ROO•, and TF (total flavonoids) showed positive correlation with the scavenging capacity against •OH and ROO• However, the scavenging capacity against H2O2 presented low correlation with TF (total flavonoids), TPC (total phenolic compounds), and AA (ascorbic acid). The Hierarchical Cluster Analysis (HCA) allowed the classification of the fruit pulps into three groups: one group was formed by the açai pulp with high TF, total flavonoids, content (134.02 mg CE/100 g pulp) and the highest scavenging capacity against ROO•, •OH and H2O2; the second group was formed by the acerola pulp with high TPC, total phenolic compounds, (658.40 mg GAE/100 g pulp) and AA , ascorbic acid, (506.27 mg/100 g pulp) contents; and the third group was formed by pineapple, cacao, caja, cashew-apple, coconut, cupuaçu, guava, orange, lemon, mango, passion fruit, watermelon, pitanga, tamarind, tangerine, and umbu pulps, which could not be separated considering only the contents of bioactive compounds and the scavenging properties.

Effect of different calcium sources on the antioxidant stability of tortilla chips from extruded and nixtamalized blue corn (Zea mays L.) flours

This research aimed to develop tortilla chips (TC) high in antioxidants from extruded and nixtamalized blue corn flours prepared with calcium hydroxide Ca(OH)2 and calcium lactate C6H10O6Ca. Tortilla chips were made with extruded flours [0.1% Ca(OH)2; 0.9% C6H10O6Ca; without calcium] and nixtamalized flours [1% Ca(OH)2; 2.95% C6H10O6Ca] using the frying process. Total anthocyanin, total phenolics content, antioxidant activity, color, texture, and oil content were determined. The color of tortilla chips from extruded flours (TCEF) showed high values of the parameters a* and b* indicating a reduction in the blue color. These color parameters were significantly different from those observed in tortilla chips from nixtamalized flours (TCNF), which tended to be more blue. The TCEF retained 15% anthocyanins, 34% phenolics, and 54% antioxidant activity. Pearson's correlation analysis indicated that anthocyanins and phenolics correlated significantly with antioxidant activity and color. TCEF with both calcium sources showed higher fracturability compared with that of TCNF. Oil absorption showed an opposite effect, with lower oil content in TCEF. Nixtamalization and extrusion with C6H10O6Ca resulted in flours and TC high in anthocyanins and antioxidant activity, representing an alternative production process for corn snack high in antioxidants.

Hypercalcemia and acute kidney injury caused by abuse of a parenteral veterinary compound containing vitamins A, D, and E

A previously healthy 19 year-old male presented to the hospital with anorexia, nausea, and vomiting. Laboratory studies were significant for hypercalcemia (peak calcium value of 14.8 mg/dL) and acute kidney injury (peak serum creatinine of 2.88 mg/dL). He admitted to using a parenteral formulation of vitamins A, D and E restricted for veterinary use containing 20,000,000 IU of vitamin A; 5,000,000 IU of vitamin D3; and 6,800 IU of vitamin E per 100 mL vial. The patient stated to have used close to 300 mL of the product over the preceding year. Interestingly, the young man was not interested in the massive amounts of vitamins that the product contained; he was only after the local effects of the oily vehicle. The swelling produced by the injection resulted in a silicone-like effect, which gave the impression of bigger muscles. Nevertheless, the product was absorbed and caused hypervitaminosis. The serum level of 25(OH) vitamin D was clearly elevated at 150 ng/mL (reference range from 30 to 60 ng/mL), but in most published cases of vitamin D toxicity, serum levels have been well above 200 ng/mL. His PTH level was undetectable and other potential causes of hypercalcemia were excluded. Therefore, we posit that the severity of the hypercalcemia observed in this case was the result of a synergistic effect of vitamins A and D. The patient was treated with normal saline, furosemide and zolendronic acid, with rapid normalization of calcium levels and renal function.

Insuficiência e deficiência de vitamina D em pacientes portadores de doença renal crônica

INTRODUÇÃO: Hipovitaminose D é bem documentada em pacientes portadores de doença renal crônica (DRC). Espera-se níveis inferiores em habitantes de regiões não tropicais em relação aos habitantes de regiões tropicais, pela inferição de uma maior exposição solar e maior produção de vitamina D. OBJETIVO: Analisar os níveis séricos de vitamina D, como 25-hidroxivitamina D - 25(OH)D, de 125 pacientes brasileiros portadores de DRC em fase pré-dialítica. MÉTODOS: Foram estudados 125 pacientes (57,4 ± 16,2 anos, 78 brancos e 55,2% homens), com creatinina de 2,67 ± 1,73 mg/dL e o clearance estimado 43,7 ± 34,5 mL/min. O índice de massa corporal era de 27,4 ± 4,7 kg/m² e a circunferência abdominal de 95,0 ± 14,0 cm. O cálcio era de 9,3 ± 0,6 mg/dL, o paratormônio intacto (PTHi) 212,6 ± 221,2 pg/mL e a albumina sérica 4,2 ± 0,6 g/dL. A média de 25(OH)D era de 23,9 ± 10,7 ng/mL. RESULTADOS: Dos 125 pacientes, 92 (72,6%) apresentavam níveis de 25(OH)D < 30 ng/mL, sendo que 65 (52%) apresentavam insuficiência (15-29 ng/mL); 27 (21,5%) apresentavam deficiência (5-14 ng/mL) e apenas um paciente apresentava deficiência severa < 5 ng/mL. Não foram observadas diferenças entre os níveis de 25(OH)D nos pacientes estratificados quanto ao estágio de DRC. Os níveis de 25(OH)D foram maiores nos homens (38,1 ± 20,6 versus 22,4 ± 9,7 ng/ml; p < 0,0001), havendo também uma correlação inversa entre os níveis de 25(OH)D e de PTHi, proteinúria e circunferência abdominal, e uma correlação positiva entre 25(OH)D e cálcio total e albumina sérica. Na análise multivariada, encontrou-se apenas correlação inversa entre 25(OH)D e circunferência abdominal e PTHi. CONCLUSÃO: A despeito de a população do Brasil estar em um clima tropical, a maioria dos pacientes analisados apresentou níveis séricos subótimos de vitamina D, podendo este achado estar relacionado ao desenvolvimento de hiperparatireoidismo.

Níveis séricos de vitamina D e periodontite crônica em pacientes com doença renal crônica

INTRODUÇÃO A concomitância de periodontite crônica (PC) em pacientes com doença renal crônica (DRC) tem sido associada a desfechos adversos. A deficiência de vitamina D (25(OH)D) parece desempenhar papel importante na PC e níveis inadequados de vitamina D têm sido descritos em pacientes com DRC. OBJETIVO: Examinar a relação entre níveis séricos de vitamina D e PC em pacientes com DRC pré-dialítica. MÉTODO: Estudo de caso-controle, definidos, respectivamente, como pacientes com DRC e PC e DRC sem PC. Os dados demográficos, de exame físico e laboratoriais foram obtidos no dia da consulta. A DRC foi definida e estagiada segundo a NKF QDOKI TM. Os níveis séricos de 25(OH) D foram dosados por quimioluminescência quando da avaliação da PC, a qual foi caracterizada segundo os critérios de Academia Americana de Periodontologia (1999). Os resultados de 25(OH)D foram estratificados em deficiência (< 14 ηg/mL), insuficiência (15-29 ηg/mL) e suficiência (> 30 ηg/mL). RESULTADOS: Um total de 29 pacientes foram estudados, 15 no grupo caso e 14 no grupo controle. Os pacientes casos apresentaram mediana de 25(OH) D inferior a dos pacientes controles (22,6 vs. 28,6 ηg/mL; p < 0,01). A frequência de pacientes casos com insuficiência/deficiência de vitamina D foi maior do que entre os pacientes controles (93,3% vs. 57,1%, p < 0,004). Por outro lado, o percentual de pacientes com suficiência de vitamina D foi maior entre os controles se comparados aos integrantes do grupo casos (42,9% vs. 6,7%, p < 0,004). CONCLUSÃO: Em pacientes com DRC, a deficiência de vitamina D se associa com PC.

Vitamin D and Kidney disease: what we know and what we do not know

Vitamin D deficiency is common in the chronic kidney disease (CKD) population. CKD has been recognized as a significant public health problem and CKD patients are at increased risk of total and cardiovascular morbidity and mortality. There are increasing epidemiological data suggesting that vitamin D deficiency may play a role in overall morbidity and mortality associated with CKD. The vitamin D hormonal system is classically implicated in the regulation of calcium homeostasis and bone metabolism but there is ample evidence to support the claim that extra renal conversion of 25(OH)D to 1.25(OH)2 has significant biological roles beyond those traditionally ascribed to vitamin D. Based on the current state of evidence this review intends to give an update on novel biological and clinical insights with relevance to the steroid hormone vitamin D specifically in patients with kidney disease.

Associação de hipovitaminose D com Lúpus Eritematoso Sistêmico e inflamação

Introdução: Atualmente, é descrita elevada prevalência de hipovitaminose D no Lúpus Eritematoso Sistêmico (LES), a qual se associa a algumas manifestações clínicas e maior atividade inflamatória. Objetivo: Avaliar a associação entre insuficiência de vitamina D com LES e marcadores inflamatórios. Métodos: Estudo transversal, tendo sido avaliados 45 pacientes com LES e 24 controles sem a doença. Níveis de 25-hidroxivitamina D [25(OH)D] menores que 30 ng/mL foram considerados insuficientes. A atividade da doença foi avaliada pelo Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Foram avaliados, ainda, proteína C reativa ultrassensível (PCRus) e interleucina-6 (IL-6) para verificação do status inflamatório. Para avaliação do envolvimento renal, foram realizados análise de elementos anormais e sedimentoscopia urinárias (EAS), hematúria e piúria quantitativas, proteinúria e depuração de creatinina em urina de 24 horas e anti-DNA de dupla hélice sérico. Resultados: A prevalência de insuficiência de 25(OH)D foi de 55% nos pacientes lúpicos e 8% nos participantes controles (p = 0,001). A mediana da 25(OH)D foi menor nos pacientes do que no grupo controle. Os pacientes com insuficiência de 25(OH)D apresentaram níveis mais elevados de IL-6 e maior prevalência de hematúria ao EAS. Não houve correlação entre vitamina D, nefrite lúpica e SLEDAI. Conclusão: Em nosso estudo, a insuficiência de vitamina D foi mais prevalente em pacientes com LES e se associou com níveis mais elevados de IL-6 e presença de hematúria.

Carponate precipitation with carbon dioxide gas

The aim of this thesis research work focused on the carbonate precipitation of magnesium using magnesium hydroxide Mg(OH)2 and carbon dioxide (CO2) gas at ambient temperature and pressure. The rate of dissolution of Mg(OH)2 and precipitation kinetics were investigated under different operating conditions. The conductivity and pH of the solution were inline monitored by a Consort meter and the solid samples gotten from the precipitation reaction were analysed by a laser diffraction analyzer Malvern Mastersizer to obtain particle size distributions (PSD) of crystal samples. Also the Mg2+ concentration profiles were determined from the liquid phase of the precipitate by ion chromatography (IC) analysis. Crystal morphology of the obtained precipitates were also investigated and discussed in this work. For the carbonation reaction of magnesium hydroxide in the present work, it was found that magnesium carbonate trihydrate (nesquehonite) was the main product and its formation occurred at a pH of around 7-8. The stirrer speed has a significant effect on the dissolution rate of Mg(OH)2. The highest obtained Mg2+ concentration level was 0.424 mol L-l for the 470 rpm and 0.387 mol L-1 for the 560 rpm which corresponded to the processing time of 45 mins and 40 mins respectively. The particle size distribution shows that the average particle size keeps increasing during the reaction as the CO2 is been fed to the system. The carbonation process is kinetically favored and simple as nesquehonite formation occurs in a very short time. It is a thermodynamically and chemically stable solid product, which allows for a long-term storage of CO2. Since the carbonation reaction is a complex system which includes dissolution of magnesium hydroxide particles, absorption of CO2, chemical reaction and crystallization, the dissolution of magnesium hydroxide was studied in hydrochloric acid (HCl) solvent with and without nitrogen (N2) inert gas. It was found on the dissolution part that the impeller speed had effect on the dissolution rate. The higher the impeller speed the higher the pH of the solution, although for the highest speed of 650rpm it was not the case. Therefore, it was concluded that the optimum speed of the stirrer was 560rpm. The influence of inert gas N2 on the dissolution rate of Mg(OH)2 particles could be seen based on measured pH, electric conductivity and Mg2+ concentration curves.

Production of magnesium carbonates from serpentinites for CO2 mineral sequestration : optimisation towards industrial application

Global warming is one of the most alarming problems of this century. Initial scepticism concerning its validity is currently dwarfed by the intensification of extreme weather events whilst the gradual arising level of anthropogenic CO2 is pointed out as its main driver. Most of the greenhouse gas (GHG) emissions come from large point sources (heat and power production and industrial processes) and the continued use of fossil fuels requires quick and effective measures to meet the world’s energy demand whilst (at least) stabilizing CO2 atmospheric levels. The framework known as Carbon Capture and Storage (CCS) – or Carbon Capture Utilization and Storage (CCUS) – comprises a portfolio of technologies applicable to large‐scale GHG sources for preventing CO2 from entering the atmosphere. Amongst them, CO2 capture and mineralisation (CCM) presents the highest potential for CO2 sequestration as the predicted carbon storage capacity (as mineral carbonates) far exceeds the estimated levels of the worldwide identified fossil fuel reserves. The work presented in this thesis aims at taking a step forward to the deployment of an energy/cost effective process for simultaneous capture and storage of CO2 in the form of thermodynamically stable and environmentally friendly solid carbonates. R&D work on the process considered here began in 2007 at Åbo Akademi University in Finland. It involves the processing of magnesium silicate minerals with recyclable ammonium salts for extraction of magnesium at ambient pressure and 400‐440⁰C, followed by aqueous precipitation of magnesium in the form of hydroxide, Mg(OH)2, and finally Mg(OH)2 carbonation in a pressurised fluidized bed reactor at ~510⁰C and ~20 bar PCO2 to produce high purity MgCO3. Rock material taken from the Hitura nickel mine, Finland, and serpentinite collected from Bragança, Portugal, were tested for magnesium extraction with both ammonium sulphate and bisulphate (AS and ABS) for determination of optimal operation parameters, primarily: reaction time, reactor type and presence of moisture. Typical efficiencies range from 50 to 80% of magnesium extraction at 350‐450⁰C. In general ABS performs better than AS showing comparable efficiencies at lower temperature and reaction times. The best experimental results so far obtained include 80% magnesium extraction with ABS at 450⁰C in a laboratory scale rotary kiln and 70% Mg(OH)2 carbonation in the PFB at 500⁰C, 20 bar CO2 pressure for 15 minutes. The extraction reaction with ammonium salts is not at all selective towards magnesium. Other elements like iron, nickel, chromium, copper, etc., are also co‐extracted. Their separation, recovery and valorisation are addressed as well and found to be of great importance. The assessment of the exergetic performance of the process was carried out using Aspen Plus® software and pinch analysis technology. The choice of fluxing agent and its recovery method have a decisive sway in the performance of the process: AS is recovered by crystallisation and in general the whole process requires more exergy (2.48–5.09 GJ/tCO2sequestered) than ABS (2.48–4.47 GJ/tCO2sequestered) when ABS is recovered by thermal decomposition. However, the corrosive nature of molten ABS and operational problems inherent to thermal regeneration of ABS prohibit this route. Regeneration of ABS through addition of H2SO4 to AS (followed by crystallisation) results in an overall negative exergy balance (mainly at the expense of low grade heat) but will flood the system with sulphates. Although the ÅA route is still energy intensive, its performance is comparable to conventional CO2 capture methods using alkanolamine solvents. An energy‐neutral process is dependent on the availability and quality of nearby waste heat and economic viability might be achieved with: magnesium extraction and carbonation levels ≥ 90%, the processing of CO2‐containing flue gases (eliminating the expensive capture step) and production of marketable products.