Severe multiple sclerosis reactivation during prolonged lymphopenia after dimethyl fumarate discontinuation.

BACKGROUND: Delayed-release dimethyl fumarate (DMF) treatment can be associated with reduced lymphocyte and leucocyte counts, which might persist after DMF discontinuation. CASE PRESENTATION: We report the case of a patient with severe disease reactivation despite prolonged lymphopenia after DMF discontinuation. We describe the frequency and impact of prolonged lymphopenia after DMF discontinuation at two tertiary MS centres. A 36-year-old female patient with multiple sclerosis was switched to DMF after 14 years of treatment with interferon beta-1a. DMF was suspended after 4 months because of persistent lymphopenia for 3 months. Six months later, the patient had a severe relapse with multiple enhancing brain lesions at MRI although lymphopenia was still persistent. Haematological assessment excluded other causes of lymphopenia, which was evaluated as a probable iatrogenic complication of DMF. The patient was treated with i.v. methylprednisolone 1 gr daily for 3 days with clinical recovery. CONCLUSIONS: Prolonged lymphopenia after DMT discontinuation does not protect against disease reactivation. Starting a new immune therapy should be balanced against the option of a "wait and see." A different immunotherapeutic strategy such as an anti-B therapeutic approach could be considered.

Relevance of asymptomatic spinal MRI lesions in patients with multiple sclerosis.

BACKGROUND: The impact of new asymptomatic spinal cord lesions (a-SL) in multiple sclerosis (MS) course is poorly characterized. OBJECTIVE: The objective of this research paper is to assess the prognostic value of a-SL in predicting MS course. METHODS: Relapsing-remitting MS patients who received serial MRI (brain and spinal) at baseline (t1) and within 12 to 36 months (t2) during clinical stability, and had a follow-up (t2-t3) ⩾24 months were included. Relapses and disability progression were evaluated between t2 and t3. RESULTS: Of 413 consecutive screened MS patients, 103 patients (65 females, median age 43 years) were included. After a median t1-t2 interval of 17 (IQR 13-26) months, 25.2% and 43.7% patients had ⩾1 new a-SL (a-SL+) and asymptomatic brain lesions (a-BL+), respectively. Relapse risk between t2 and t3 (median interval: 42 (IQR 32-57.5) months) was significantly increased in a-SL+ and/or a-BL+ vs a-BL- and a-SL- (HR = 2.31, 95% CI = 1.13-4.72, p = 0.02). No differences in the risk of disability progression were found in a-SL+ and/or a-BL+ vs a-SL- and a-BL-. CONCLUSION: a-SL occur in one-quarter of clinically stable RRMS, and combined with a-BL contribute significantly in predicting future disease course.

Urinary incontinence in multiple sclerosis: prevalence, severity and impact on patients' quality of life.

BACKGROUND AND PURPOSE: Lower urinary tract symptoms (LUTS) including frequent urination, nocturia and urge urinary incontinence negatively impact quality of life. This project aimed at characterizing the prevalence and severity of urinary incontinence in multiple sclerosis (MS) patients and its association with demographic and clinical features. METHODS: In all, 403 consecutive clinically stable MS patients answered the International Consultation on Incontinence Questionnaire (ICIQ) and the Patient Perception of Bladder Condition (PPBC) questionnaire. Demographic and clinical parameters including the Expanded Disability Status Scale (EDSS) were collected. Statistical analyses were performed using univariate and multivariate linear regression models. RESULTS: Females represented 72%, relapsing-remitting patients 82%. The mean (SD) disease duration and EDSS were 11.8 (8.6) years and 3.1 (1.9) respectively. Approximately 35% of patients reported urine incontinence. ICIQ scores were positively associated with EDSS, female gender, presence of LUTS therapies and absence of disease modifying treatments (P < 0.001). PPBC scores were positively associated with EDSS and the presence of LUTS therapies (P < 0.001). DISCUSSION: Urinary incontinence is frequent in MS, prevailing in more disabled and female patients. Currently available LUTS therapies appear insufficient in the treatment of this symptom. The negative impact of urinary incontinence on quality of life is high and requires more attention in clinical management and research.

Maintenance percutaneous posterior nerve stimulation for refractory lower urinary tract symptoms in patients with multiple sclerosis: an open label, multicenter, prospective study.

PURPOSE: Percutaneous tibial nerve stimulation is an effective second line therapy for lower urinary tract symptoms. Data on percutaneous tibial nerve stimulation maintenance treatment are scarce. In this study we evaluate its effectiveness and propose an algorithm of percutaneous tibial nerve stimulation maintenance treatment in patients with multiple sclerosis. MATERIALS AND METHODS: In this prospective, multicenter, open label trial consecutive patients with multiple sclerosis and lower urinary tract symptoms unresponsive to medical therapy were treated with 12 weekly sessions of percutaneous tibial nerve stimulation. Responder patients (50% or greater improvement of lower urinary tract symptoms as measured by the patient perception of bladder condition questionnaire) entered a maintenance phase with individualized treatment frequency based on patient response. Lower urinary tract symptoms were assessed using a 3-day frequency volume chart, urodynamics and patient perception of bladder condition questionnaire. Treatment satisfaction was evaluated using a global response assessment scale and a treatment satisfaction visual analog scale. RESULTS: A total of 83 patients were included in the study and 74 (89%) responded to initial treatment. Persistent efficacy occurred in all initial responders after a mean treatment of 24 months. The greatest frequency of maintenance percutaneous tibial nerve stimulation was every 2 weeks. Lower urinary tract symptoms and patient treatment satisfaction improved with time compared to initial treatment (p <0.05). Bladder diary parameters and voiding parameters improved compared to baseline (p <0.05). CONCLUSIONS: Prolonged percutaneous tibial nerve stimulation treatment leads to a persistent improvement of lower urinary tract symptoms in patients with multiple sclerosis.

Influence of the topography of brain damage on depression and fatigue in patients with multiple sclerosis.

OBJECTIVES: Involvement of selected central nervous system (CNS) regions has been associated with depression and fatigue in MS. We assessed whether specific regional patterns of lesion distribution and atrophy of the gray (GM) and white matter (WM) are associated with these symptoms in MS. METHODS: Brain dual-echo and 3D T1-weighted images were acquired from 123 MS patients (69 depressed (D), 54 non-depressed (nD), 64 fatigued, 59 non-fatigued) and 90 controls. Lesion distribution, GM and WM atrophy were estimated using VBM and SPM8. RESULTS: Gender, age, disease duration and conventional MRI characteristics did not differ between D-MS and nD-MS patients. Fatigued patients experienced higher EDSS and depression than non-fatigued ones. Lesion distribution and WM atrophy were not related to depression and fatigue. Atrophy of regions in the frontal, parietal and occipital lobes had a combined effect on depression and fatigue. Atrophy of the left middle frontal gyrus and right inferior frontal gyrus were selectively related to depression. No specific pattern of GM atrophy was found to be related to fatigue. CONCLUSIONS: Depression in MS is linked to atrophy of cortical regions located in the bilateral frontal lobes. A distributed pattern of GM atrophy contributes to the concomitant presence of depression and fatigue in these patients.

Forceps minor damage and co-occurrence of depression and fatigue in multiple sclerosis.

OBJECTIVE: Using diffusion tensor magnetic resonance imaging (DT MRI), we analyzed the architectural integrity of the brain white matter (WM) from a large cohort of MS patients to identify the structural substrates of the concomitant presence of depression and fatigue. METHODS: Brain dual-echo, 3D T1-weighted and DT MRI scans were acquired from 147 MS patients and 90 gender- and age-matched healthy controls (HCs). Patients were stratified by the presence of depression (92 depressed (D), 55 not depressed (nD)) and fatigue (81 fatigued (F), 66 not fatigued (nF)). Sixty-five patients had co-occurrence of depression and fatigue (DF). Whole-brain voxel-wise comparisons of WM DT MRI abnormalities were performed using tract-based-spatial-statistics (TBSS). Tract-specific analyses were run in brain WM tracts using standard-space templates. RESULTS: Whole-brain voxel-wise analysis yielded no significant differences between patient subgroups. At tract-specific analysis, DF patients had reduced fractional anisotropy (FA) of the forceps minor. Reduced FA of the right anterior thalamic radiation and right uncinate fasciculus was found in F-MS vs not F-MS patients after correcting for depression. No significant differences were found between D vs not D-MS patients, after correcting for fatigue. CONCLUSIONS: This study provides evidence for partially overlapping damage to frontal and fronto-temporal pathways underlying depression and fatigue in MS.

Motor and sensory responses after percutaneous tibial nerve stimulation in multiple sclerosis patients with lower urinary tract symptoms treated in daily practice.

BACKGROUND AND PURPOSE: Posterior tibial nerve stimulation (PTNS) is an effective treatment option for lower urinary tract symptoms (LUTS) in multiple sclerosis (MS) patients. METHODS: Patients with MS and LUTS unresponsive to medical treatment received PTNS for 12 weeks after saline urodynamics to evaluate the prevalence of motor, sensory and combined responses during PTNS and to determine whether the type of response can predict treatment outcome. LUTS were also assessed using a 3-day bladder diary, patient perception of bladder condition (PPBC) questionnaire, patient perception of intensity of urgency scale (PPIUS), Kings Health QOL questionnaire (KHQ) and Overactive Bladder Questionnaire (OAB-q) before and after treatment. Patients were considered as "responders" if they reported an improvement >50% in their LUTS according to the PPBC. Sensory, motor and combined sensory/motor responses were compared between responders and non-responders. RESULTS: Eighty-three patients were included. 61% (51/83) of patients were responders. Sensory, motor and combined sensory/motor responses were found in 64% (53/83), 6% (5/83) and 30% (25/83) of patients respectively. A sensory response alone, or in combination with a motor response, was better associated with a successful outcome than the presence of a motor response alone (P = 0.001). CONCLUSIONS: A sensory response, either alone or in combination with a motor response, is more frequent and seems to be better associated with a successful outcome of PTNS than motor response alone.

Fumaric acid esters in psoriasis and multiple sclerosis.

Fumaric acid esters (FAEs) are effective in patients with moderate to severe psoriasis. Recent studies also report the efficacy of one FAE component, dimethylfumarate, in relapsing forms of multiple sclerosis (MS). We describe the case of a patient with MS who developed severe plaque psoriasis during interferon-ß-1a treatment for MS. The psoriasis was unresponsive to usual topical treatments and phototherapy. The patient was started on FAE 720 mg daily, with complete remission of the psoriatic lesions and neurological stabilization at follow-up at 24 months. Our case suggests that FAEs could represent a therapeutic option for patients with MS who develop plaque psoriasis following exposure to immune-modulating agents.

Tumefactive demyelinating lesions during etanercept treatment requiring decompressive hemicraniectomy.

Tumor necrosis factor alpha (TNF-α) is a pro-inflammatory and immunoregulatory cytokine involved in the pathogenesis of several autoimmune disorders. Etanercept, a TNF-α antagonist (anti-TNF-α) acting as a soluble TNF-α receptor, has been associated with neurological demyelinating disorders. This paper aims to report an unusual case showing tumefactive central nervous system (CNS) inflammatory demyelination in a patient in the course of TNF -α antagonist therapy, requiring decompressive hemicraniectomy. This report is based on magnetic resonance imaging (MRI) findings and histology. A biopsy confirmed the inflammatory demyelinating nature of the lesions. The clinical presentation is unusual due to the severity of the disease process, requiring decompressive hemicraniotomy with a clinically favorable outcome.

The treatment of lower urinary tract symptoms in patients with multiple sclerosis: a systematic review.

This is a systematic review on the treatment of lower urinary tract symptoms (LUTS) in patients with multiple sclerosis (MS). The heterogeneity of the outcome criteria did not allow a meta-analysis of the published evidence. In the last few decades, the therapeutic options for neurogenic bladder dysfunction have broadened. Despite this, no consensus has been reached as to the management of LUTD and LUTS in patients with MS, and the subject remains controversial. Bladder dysfunction is common in MS, affecting 80 %-100 % of patients during the course of the disease. Several studies have shown that urinary incontinence has a severe effect on patients' quality of life, with 70 % of patients classifying the impact bladder symptoms had on their life as "high" or "moderate." Moreover, the progressive feature of MS makes its treatment complex, since any achieved therapeutic result may be short-lived, with the possibility that symptoms will recur or develop de novo.

Prognostic biomarkers in primary progressive multiple sclerosis: Validating and scrutinizing multimodal evoked potentials.

OBJECTIVE: To validate the prognostic value of multimodal evoked potentials (mmEP) in primary progressive multiple sclerosis (PPMS) and to determine the most predictive EP-modalities. METHODS: Thirty-nine patients with PPMS (expanded disability status scale (EDSS): 2.0-6.5; mean clinical follow-up: 2.8 years) had visual (VEP), upper and lower limb somatosensory (SEP) and motor EP (MEP) at baseline. Quantitative EP-scores for single (qVEP, qSEP, qMEP) and combined modalities were correlated to EDSS and compared to previously published data of 21 PPMS patients. Predictors of EDSS-change were analyzed in pooled data by linear regression. RESULTS: Samples were comparable. Except qVEP, all EP-scores were correlated to EDSS at baseline (Rho: 0.45-0.69; p < 0.01) and follow-up (Rho: 0.59-0.80; p < 0.001). Combined EP-modalities significantly predicted EDSS-change (R2adj: 0.24), while EDSS and age did not. Tibial qSEP (R2adj: 0.22) and qMEP (R2adj: 0.26) were the best single modality predictors, outperformed by their combination (R2adj: 0.32). CONCLUSIONS: Quantitative EP-scores predict up to 32% of EDSS-change over three years. Modalities representing motor and long tract function carry the main prognostic information. SIGNIFICANCE: Replication of previous results corroborates the use of mmEP as a prognostic biomarker candidate in PPMS.

Nonlesional Sources of Contrast Enhancement on Postgadolinium "Black-Blood" 3D T1-SPACE Images in Patients with Multiple Sclerosis.

BACKGROUND AND PURPOSE: We hypothesized that 3D T1-TSE "black-blood" images may carry an increased risk of contrast-enhancing lesion misdiagnosis in patients with MS because of the misinterpretation of intraparenchymal vein enhancement. Thus, the occurrence of true-positive and false-positive findings was compared between standard MPRAGE and volumetric interpolated brain examination techniques. MATERIALS AND METHODS: Sampling perfection with application-optimized contrasts by using different flip-angle evolution (SPACE) images obtained from 232 patients with MS, clinically isolated syndrome, or radiologically isolated syndrome were compared with standard MPRAGE and volumetric interpolated brain examination images. The intraparenchymal vein contrast-to-noise ratio was estimated at the level of the thalami. Contrast-enhancing lesions were blindly detected by 2 expert readers and 1 beginner reader. True- and false-positives were determined by senior readers' consensus. True-positive and false-positive frequency differences and patient-level diagnosis probability were tested with the McNemar test and OR. The contrast-to-noise ratio and morphology were compared using the Mann-Whitney U and χ2 tests. RESULTS: The intraparenchymal vein contrast-to-noise ratio was higher in SPACE than in MPRAGE and volumetric interpolated brain examination images (P < .001, both). There were 66 true-positives and 74 false-positives overall. SPACE detected more true-positive and false-positive results (P range < .001-.07) but did not increase the patient's true-positive likelihood (OR = 1 1.29, P = .478-1). However, the false-positive likelihood was increased (OR = 3.03-3.55, P = .008-.027). Venous-origin false-positives (n = 59) with contrast-to-noise ratio and morphology features similar to small-sized (≤14 mm3 P = .544) true-positives occurred more frequently in SPACE images (P < .001). CONCLUSIONS: Small intraparenchymal veins may confound the diagnosis of enhancing lesions on postgadolinium black-blood SPACE images.

Percutaneous posterior tibial nerve stimulation as an effective treatment of refractory lower urinary tract symptoms in patients with multiple sclerosis: preliminary data from a multicentre, prospective, open label trial.

BACKGROUND: Percutaneous tibial nerve stimulation (PTNS) has been proposed as a new, minimally invasive neuromodulation technique to treat lower urinary tract symptoms (LUTS). OBJECTIVE: To evaluate efficacy, safety and impact on quality of life (QoL) of PTNS on patients with multiple sclerosis (MS) who have LUTS. METHODS: 21 patients (5 men, 16 women) with MS and LUTS unresponsive to anticholinergics were treated with 12 sessions of PTNS. Assessment of LUTS was by validated, self-administered chart and questionnaires, testing the subjective and objective relevance of LUTS for patients and their impact on QoL before and after treatment; the mean post-micturition residual was assessed by trans-abdominal ultrasound scanning. Analysis was by intention to treat. RESULTS: There was a significant reduction of daytime frequency (from 9 to 6, p = 0.04), nocturia (from 3 to 1, p = 0.002) and mean post-micturition residual (from 98 ± 124 ml to 43 ± 45 ml, p = 0.02). The mean voided volume increased from 182 ± 50 ml to 225 ± 50 ml (p = 0.003). Eighty-nine percent of patients reported a treatment satisfaction of 70%. Significant improvement in QoL was seen in most domains of the King's Health QoL questionnaire (p < 0.05). No adverse events were reported. CONCLUSIONS: PTNS is an effective, safe and well-tolerated treatment for LUTS in patients with MS.

Cell apoptosis and proliferation in salivary glands of Sjögren's syndrome.

BACKGROUND: Sjögren's syndrome (SS) occurs associated with parotid neoplasm, non-Hodgkin's B-cell lymphoma, which could impair the condition or be life-threatening for patients. The aim of this work was to analyze cell proliferation and apoptosis modifications in acinar, ductal and inflammatory infiltrate in salivary glands (SG) in patients with Sjögren Syndrome, keratoconjunctivitis, or stomatitis sicca or in healthy subjects, to establish parameters that indicate the likelihood of malignancy of the disease in populations at risk. METHODS: A study was performed with n = 58 histological samples of lower lip SG from patients diagnosed with SS, keratoconjunctivitis, or stomatitis sicca (SICCA) and from healthy subjects (C). Ki67 and caspase-3 immunolabeling were performed. RESULTS: The most important result was significant differences between the three study groups in Ki67 and caspase-3 markers (P < 0.0001) in infiltrated lymphocytes. CONCLUSION: The results of this work are indicative of a high degree of proliferation (85%) in infiltrated lymphocytes (IL) associated with SS which, according the literature, could be considered a risk. Furthermore, the markers used in this work are widely known and represent a lower cost than others and can be used to determine risk groups within the population of SS patients, enabling their follow-up.

[Bacterial endocarditis caused by salmonella in systemic lupus erythematosus]. / Endocarditis por salmonella en lupus eritematoso sistemico.

INTRODUCTION: Patients with SLE (Systemic Lupus Erythematosus) are prompt to develop infections with significant morbidity and mortality. The intravascular infection due to salmonella is a rare complication of difficult diagnosis and poor prognostic. OBJECTIVE: We report two cases of bacterial endocarditis due to salmonella in SLE patients. CLINICAL CASES: We report two cases of bacterial endocarditis caused by Salmonella in a patient with SLE, one with recent onset of mellitus diabetes and other with chronic renal failure. Despite of antibiotic treatment with fluoroquinolone and a third-generation cephalosporin, the patient required surgical intervention. CONCLUSION: Salmonella infection should be suspected in SLE patients in order to make earlier diagnosis and treatment.

Dedicated 3D-T2-STIR-ZOOMit Imaging Improves Demyelinating Lesion Detection in the Anterior Visual Pathways of Patients with Multiple Sclerosis.

BACKGROUND AND PURPOSE: Demyelinating lesions in the anterior visual pathways represent an underestimated marker of disease dissemination in patients with MS. We prospectively investigated whether a dedicated high-resolution MR imaging technique, the 3D-T2-STIR-ZOOMit, improves demyelinating lesion detection compared with the current clinical standard sequence, the 2D-T2-STIR. MATERIALS AND METHODS: 3T MR imaging of the anterior visual pathways (optic nerves, chiasm, and tracts) was performed using 3D-T2-STIR-ZOOMit and 2D-T2-STIR, in patients with MS and healthy controls. Two experienced neuroradiologists assessed, independently, demyelinating lesions using both sequences separately. 3D-T2-STIR-ZOOMit scan-rescan reproducibility was tested in 12 patients. The Cohen κ was used for interrater agreement, and the intraclass correlation coefficient for reproducibility. Between-sequence detection differences and the effects of location and previous acute optic neuritis were assessed using a binomial mixed-effects model. RESULTS: Forty-eight patients with MS with (n = 19) or without (n = 29) past optic neuritis and 19 healthy controls were evaluated. Readers' agreement was strong (3D-T2-STIR-ZOOMit: 0.85; 2D-T2-STIR: 0.90). The 3D-T2-STIR-ZOOMit scan-rescan intraclass correlation coefficient was 0.97 (95% CI, 0.96-0.98; P < .001), indicating excellent reproducibility. Overall, 3D-T2-STIR-ZOOMit detected more than twice the demyelinating lesions (n = 89) than 2D-T2-STIR (n = 43) (OR = 2.7; 95% CI, 1.7-4.1; P < .001). In the intracranial anterior visual pathway segments, 33 of the 36 demyelinating lesions (91.7%) detected by 3D-T2-STIR-ZOOMit were not disclosed by 2D-T2-STIR. 3D-T2-STIR-ZOOMit increased detection of demyelinating lesion probability by 1.8-fold in patients with past optic neuritis (OR = 1.8; 95% CI, 1.2-3.1; P = .01) and 5.9-fold in patients without past optic neuritis (OR = 5.9; 95% CI, 2.5-13.8; P < .001). No false-positive demyelinating lesions were detected in healthy controls. CONCLUSIONS: Dedicated 3D-T2-STIR-ZOOMit images improved substantially the detection of MS disease dissemination in the anterior visual pathways, particularly in the intracranial segments and in patients without past optic neuritis.

Infusion-related reactions during Natalizumab treatment: Do we still need a post-infusion observation period?

BACKGROUND: Natalizumab (NTZ) is a humanized monoclonal antibody used in the treatment of relapsing remitting multiple sclerosis. Although NTZ is usually well-tolerated, infusion-related reactions (IRRs) may occur, and the patients have to be monitored during the infusion and for one hour afterwards. OBJECTIVE: To identify frequency and severity of IRRs during NTZ infusions and one-hour post-infusion observation period in a clinical practice setting. METHODS: Multicenter, observational study involving three Swiss (Lugano, St. Gallen and Luzern) and two Italian (Milano and Napoli) tertiary MS centers. Predisposing factors to IRRs were investigated using multivariate Cox regression models. RESULTS: A total of 11'133 infusions received by 302 MS patients were analyzed (68.9% females, median age 33.6 years, median EDSS 2.5). IRRs occurred in 24 (8%) patients during NTZ infusions and in 7 (2%) during one-hour post-infusion. Only 8 patients needed pharmacological treatment, of whom 7 during NTZ infusion. Age, sex and history of allergies were not associated with risks for IRR. The frequency of post infusion IRRs after the fifth cycle was low compared to that during the first four infusions (0.83% vs 0.06%). CONCLUSION: In our cohort, NTZ associated IRR mainly occurred during the infusion period compared to the one-hour observational period. Also, the first IRR exclusively occurred within the first 4 NTZ administrations. However, further multi-center studies with a larger sample size are needed to capture rare and serious events that could emerge during the observational period and to make clinical recommendations.

Factors influencing patient satisfaction with the first diagnostic consultation in multiple sclerosis: a Swiss Multiple Sclerosis Registry (SMSR) study.

BACKGROUND: Patient satisfaction is predictive of adherence, malpractice litigation and doctor-switching. OBJECTIVE: To investigate which factors of the first diagnostic consultation (FDC) influence patient satisfaction and which topics persons with multiple sclerosis (PwMS) thought were missing. METHODS: Using retrospective patient-reported data of the Swiss Multiple Sclerosis Registry from PwMS with relapsing disease onset, we fitted ordered logistic regression models on satisfaction with FDC, with socio-demographic and FDC features as explanatory factors. RESULTS: 386 PwMS diagnosed after 1995 were included. Good satisfaction with the FDC was associated with a conversation more than 20 min [multivariable odds ratio, 95% confidence interval 3.9 (2.42; 6.27)], covering many topics [1.35 (1.19; 1.54) per additional topic], the presence of a significant others [1.74 (1.03; 2.94) ], and shared decision making [3.39 (1.74; 6.59)]. Not receiving a specific diagnosis was main driver for low satisfaction [0.29 (0.15; 0.55)]. Main missing topics concerned long-term consequences (reported by 6.7%), psychological aspects (6.2%) and how to obtain support and further information (5.2%). CONCLUSIONS: A conversation of more than 20 min covering many MS relevant topics, a clear communication of the diagnosis, the presence of a close relative or significant other, as well as shared decision making enhanced patient satisfaction with the FDC. ClinicalTrials.gov Identifier: NCT02980640.

Assessment of the impact of salinity and irradiance on the combined carbon dioxide sequestration and carotenoids production by Dunaliella salina: A mathematical model.

Current anthropogenic activities have been causing a significant increase in the atmospheric concentration of CO2 over the past 60 years. To mitigate the consequent global warming problem, efficient technological solutions, based on economical and technical grounds, are required. In this work, microalgae are studied as important biological systems of CO2 fixation into organic compounds through photosynthesis. These microorganisms are potential sources of a wide variety of interesting chemical compounds, which can be used for commercial purposes, reducing the cost of CO2 capture and sequestration. Specifically, Dunaliella salina culture was studied aiming at the impact evaluation of operational conditions over cellular growth and carotenoid production associated with the CO2 sequestration on focus. The main experimental parameters investigated were salinity and irradiance conditions. The experimental results supported the development of a descriptive mathematical model of the process. Based on the proposed model, a sensitivity analysis was carried out to investigate the operational conditions that maximize CO2 consumption and carotenoid production, in order to guide further development of technological routes for CO2 capture through microalgae. A preliminary cost estimation of CO2 sequestration combined to carotenoids production for a 200 MW power plant is presented, based on the growth rates achieved in this study.