Early diagnosis of sickle cell disease at birth hospitals and vaccination centers in Angola using point-of-care tests.

Sickle cell disease (SCD) is a life-threatening blood disorder affecting >500 000 infants annually, mostly in sub-Saharan Africa. Most infants do not have access to an early diagnosis and die early from treatable complications of SCD. Universal newborn screening (NBS) is not yet available in any African country for a variety of reasons, including lack of laboratory capacity, difficulty in tracking affected infants, and the relatively short stay of mothers and newborns at maternity hospitals. Several point-of-care (POC) tests for SCD have been recently developed and validated, but the 2 most well-established tests (Sickle SCAN and HemoTypeSC) have not been rigorously compared with one another. In this study, we aimed to evaluate and compare these 2 POC tests to screen infants aged ≤6 months in Luanda, Angola. Challenging the traditional NBS paradigm, we performed testing not only at maternity centers, but also at vaccination centers across Luanda. We enrolled 2000 babies and performed 1000 tests with each POC test. Both tests demonstrated diagnostic accuracy, with 98.3% of Sickle SCAN results and 95.3% of HemoTypeSC results aligning with the gold standard isoelectric focusing hemoglobin pattern. When the result was provided at the POC, 92% of infants were linked to SCD care compared with 56% in the pilot Angolan NBS program, which used centralized laboratory testing. This study demonstrates the real-world feasibility and accuracy of POC tests to screen infants for SCD in Angola. This study also suggests that including vaccination centers may improve the capture rate for early infant SCD screening programs.

Phospholipase A2 and Ischemic Stroke Etiology.

BACKGROUND: Lipoprotein-associated phospholipase A2 (Lp-PLA2), which is involved in the inflammatory atherosclerotic process, has emerged as an independent risk factor for atheromatous vascular events. Its impact on coronary disease has already been demonstrated, however, its influence in cerebrovascular etiology is still unknown. We aimed to observe and describe the potential association between Lp-PLA2 levels and the etiologic subtype of ischemic stroke. METHODS: Unicentric, observational, and prospective cohort study of consecutive patients with acute ischemic stroke, admitted in a comprehensive stroke center. Patients with incomplete investigation or coexisting causes were excluded. Lp-PLA2 was dosed in peripheral blood between day 3 and 14 postevent with "Lp-PLA2-SNIBE" kit. Statistical significance was set for P<0.05. RESULTS: A total of 96 patients were enrolled, with mean age of 75.31±11.88 years, 41 males (42.7%); 12.5% with lacunar stroke, 16.7% atherothrombotic, 46.9% cardioembolic, and 24% embolic stroke of undetermined source (ESUS). The level of Lp-PLA2 was different between etiologies (F=2.982, P=0.035), being lower in ESUS (143.3±42.8 ng/mL). There were no significant associations with previous vascular risk factors, history of ischemic stroke and modified-Rankin scale (mRS) score 3 months postevent. In ESUS patients, Lp-PLA2 was not associated with cervical ultrasound findings or frequent supraventricular extrasystoles. CONCLUSIONS: Lp-PLA2 levels are different between etiologic subtypes of ischemic stroke, being lower in ESUS patients. The results of this study reinforce the existence of distinct pathophysiological mechanisms in patients with ESUS. Multicenter clinical trials with larger sample sizes are needed to clarify the role Lp-PLA2 on the etiology of stroke.

Addition of the Aß42/40 ratio to the cerebrospinal fluid biomarker profile increases the predictive value for underlying Alzheimer's disease dementia in mild cognitive impairment.

BACKGROUND: Cerebrospinal fluid (CSF) biomarkers have been used to increase the evidence of underlying Alzheimer's disease (AD) pathology in mild cognitive impairment (MCI). However, CSF biomarker-based classification often results in conflicting profiles with controversial prognostic value. Normalization of the CSF Aß42 concentration to the level of total amyloid beta (Aß), using the Aß42/40 ratio, has been shown to improve the distinction between AD and non-AD dementia. Therefore, we evaluated whether the Aß42/40 ratio would improve MCI categorization and more accurately predict progression to AD. METHODS: Our baseline population consisted of 197 MCI patients, of which 144 had a follow-up ≥ 2 years, and comprised the longitudinal study group. To establish our own CSF Aß42/40 ratio reference value, a group of 168 AD-dementia patients and 66 neurological controls was also included. CSF biomarker-based classification was operationalized according to the framework of the National Institute of Aging-Alzheimer Association criteria for MCI. RESULTS: When using the core CSF biomarkers (Aß42, total Tau and phosphorylated Tau), 30% of the patients fell into the high-AD-likelihood (HL) group (both amyloid and neurodegeneration markers positive), 30% into the low-AD-likelihood group (all biomarkers negative), 28% into the suspected non-Alzheimer pathophysiology (SNAP) group (only neurodegeneration markers positive) and 12% into the isolated amyloid pathology group (only amyloid-positive). Replacing Aß42 by the Aß42/40 ratio resulted in a significant increase in the percentage of patients with amyloidosis (42-59%) and in the proportion of interpretable biological profiles (61-75%), due to a reduction by half in the number of SNAP cases and an increase in the proportion of the HL subgroup. Survival analysis showed that risk of progression to AD was highest in the HL group, and increased when the Aß42/40 ratio, instead of Aß42, combined with total Tau and phosphorylated Tau was used for biomarker-based categorization. CONCLUSIONS: Our results confirm the usefulness of the CSF Aß42/40 ratio in the interpretation of CSF biomarker profiles in MCI patients, by increasing the proportion of conclusive profiles and enhancing their predictive value for underlying AD.

Influence of Butyrylcholinesterase in Progression of Mild Cognitive Impairment to Alzheimer's Disease.

BACKGROUND: Several demographic and genetic prognostic factors of conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD) have been recognized so far. The most frequent polymorphism of butyrylcholinesterase (BuChE), the K-variant, has been proposed as a risk factor for AD, but data regarding its influence on early disease progression is still limited. OBJECTIVE: To investigate the influence of the BuChE-K variant in MCI progression to AD. METHODS: 96 MCI patients were included in the study and were genotyped for BuChE-K variant and Apolipoprotein E (ApoE). Cerebrospinal fluid (CSF) BuChE activity, as well as the levels of AD biomarkers amyloid-ß 42 (Aß42), total and hyperphosphorylated tau (t-tau and p-tau) were also determined. RESULTS: No significant differences were found in either BuChE-K variant or BuChE activity between MCI patients that progressed to AD (MCI-AD) and patients that remained stable during clinical follow-up (MCI-St). As expected, baseline CSF levels of Aß42 were significantly lower and t-Tau, p-Tau, and ApoE ɛ4 allele frequency were significantly higher in MCI-AD patients. An association between the ApoE ɛ4 allele and the BuChE-K variant in MCI-AD, but not in MCI-St patients, was found with patients carrying both alleles presenting the highest incidence of progression and the lowest estimated time of progression to AD. CONCLUSION: Although BuChE-K alone does not seem to play a major role in progression to AD in MCI patients, a synergistic effect with the ApoE ɛ4 allele was found, highlighting the importance of assessing these combined genotypes for evaluating risk progression in MCI patients.

Association between butyrylcholinesterase and cerebrospinal fluid biomarkers in Alzheimer's disease patients.

The deficit of cholinergic activity is one of the main findings in Alzheimer's disease (AD), and is related to the synthesis of acetylcholine, and the hydrolysing enzymes, acetylcholinesterase and butyrylcholinesterase (BuChE). Together with the Apolipoprotein E-ε4 allele (ApoE-ε4), the BuChE-K variant has been proposed to increase AD risk in certain populations. In addition, this polymorphism has been associated with a lower capacity to attenuate ß-amyloid aggregation. In the present study we explored the interaction of the BuChE-K variant with its activity in CSF, conventional AD biomarkers and ApoE genotype. 217 AD patients and 200 age-matched controls were genotyped for the ApoE and the BuChE-K variant. BuChE activity in CSF, as well as the levels of the CSF-AD biomarkers amyloid-beta 42 (Aß42), total and hyperphosphorylated tau (t-tau and p-tau) were determined in 88 of these patients. The results showed no significant differences in the BuChE-K variant distribution between patients and controls. No influence of the BuChE-K variant was seen neither in CSF BuChE activity, nor in the levels of Aß42, t-tau and p-tau in AD patients. ApoE genotype also did not seem to influence CSF BuChE activity. Interestingly, in AD patients, an association between high CSF BuChE activity and increased levels of CSF Aß42 was shown, particularly in ApoE-ε4 allele carriers. In our population, the BuChE-K variant does not seem to confer risk for AD or to influence the activity of the enzyme in CSF. However, we demonstrated an association between BuChE activity, ApoE-ε4 genotype and CSF Aß42 levels, highlighting the importance of assessing BuChE activity as a possible modulator of Aß load in the brain.

Multiple sclerosis: Association of gelatinase B/matrix metalloproteinase-9 with risk and clinical course the disease.

BACKGROUND: Multiple sclerosis (MS) is an autoimmune disease characterized by inflammation and axonal degeneration of the central nervous system and a leading cause of disability in young adults. The matrix metalloproteinases in general and specially gelatinase B/metalloproteinase-9 (MMP-9) plays a role in the pathogenesis of multiple sclerosis. OBJECTIVE: To investigate the presence of the MMP-9 -1562C/T polymorphism in a Portuguese population of MS patients and assess its impact in susceptibility and course of the disease. The relation of MMP-9 serum levels with the polymorphism and with clinical and therapeutic factors will also be assessed. METHODS: Our study included 355 Caucasian individuals distributed as MS patients (n=169) and controls (n=186). Samples were genotyped for -1562C/T polymorphism by PCR-RFLP analysis. MMP-9 concentration in serum was analyzed using a commercially available enzyme-linked immunosorbent assay. RESULTS: A significant increase in T-allele frequency was found in female MS patients, but not in the total patient population. No association between the presence of the polymorphism and disease progression was found. MMP-9 serum concentrations were increased in patients, and although not influenced by the -1562C/T polymorphism, were modified by INF-beta therapy. CONCLUSION: Although we did not find an association of this polymorphism with disease susceptibility or prognosis, MMP-9 appears to be a good therapeutic response marker for multiple sclerosis.

Cerebrospinal fluid Aß40 is similarly reduced in patients with Frontotemporal Lobar Degeneration and Alzheimer's Disease.

Cerebrospinal fluid (CSF) biomarkers have been increasingly studied for dementia diagnosis, however the accuracy to distinguish between different forms of dementia is still unsatisfactory. In this study, the added value of another CSF Aß-peptide (Aß40), along with the core CSF markers t-Tau, p-Tau, and Aß42, in the discrimination between two large dementia groups of Frontotemporal Lobar Degeneration (FTLD; n=107), Alzheimer's Disease (AD; n=107) and non-demented subjects (n=33) was evaluated. In FTLD, t-Tau and p-Tau were significantly increased in relation to controls, but lower than in AD, while Aß42 was similar in FTLD and controls, but higher than in AD. Equally reduced Aß40 levels were seen in both dementia groups, and therefore the combination of Aß40 with core CSF biomarkers optimally discriminated FTLD and AD patients from controls. Aß42 and t-Tau were selected as the best biomarker subset to differentiate FTLD from AD, with no added value of Aß40 to the model. Diagnostic accuracy between FTLD and AD was still sub-optimal, with a significant percentage (23%) of FTLD patients, in particularly women, carrying an ApoE-ε4 allele, showing a CSF-AD biomarkers profile. Although CSF Aß40 does not appear to have an additional value in the distinction between FTLD and AD, it increases the discrimination between subjects with dementia from controls. A CSF-AD biomarker profile can be seen in patients with a clinical phenotype of FTLD, reinforcing the need for autopsy confirmation.

Oxidative damage and progression to Alzheimer's disease in patients with mild cognitive impairment.

Recent studies show that most of the oxidative changes found in Alzheimer's disease (AD) are already present in mild cognitive impairment (MCI) patients. The question arises as to whether oxidative stress has a role in the progression of MCI to AD. We conducted a longitudinal study on 70 MCI patients, and the peripheral blood levels of a broad spectrum of non-enzymatic and enzymatic antioxidant defenses, as well as lipid and protein oxidation markers and nitrogen oxidative species were determined. At baseline, there were no differences in any of the indexes of oxidative damage between stable MCI patients (MCI-MCI) and patients that progressed to AD (MCI-AD). Cellular levels of lipid peroxidation markers increased in both groups and this was accompained in MCI-AD, but not in MCI-MCI patients, by a significant decrease in cellular antioxidant defenses (oxidyzed/reduced glutathione ratio and vitamin E). Among MCI-AD patients, the longitudinal decrease in cellular vitamin E was associated with the deterioration in cognitive performance. These results suggest that accumulation of oxidative damage may start in pre-symptomatic phases of AD pathology and that progression to AD might be related to depletion of antioxidant defenses.

Peripheral oxidative damage in mild cognitive impairment and mild Alzheimer's disease.

Oxidative stress has been shown to be a triggering event in the pathogenesis of Alzheimer's disease (AD). However, little evidence exists on the role of oxidative imbalance in Mild Cognitive Impairment (MCI), a group with a high risk of progression to AD. We therefore assessed the peripheral blood levels of a broad spectrum of non-enzymatic and enzymatic antioxidant defenses, as well as lipid and protein oxidation markers and nitrogen oxidative species in 85 MCI patients, 42 mild AD patients and 37 age-matched controls. In mild AD patients, the plasma levels of vitamin E were significantly decreased, while the plasma concentration of oxidized glutathione was increased in both MCI and mild AD patients. An increase in plasmatic and erythrocytes oxidative markers was also observed in MCI and mild AD patients as compared to controls. In both patients groups, increased levels of plasma antioxidants were found in females, whereas apolipoprotein E epsilon4 allele carriers showed higher indices of intracellular oxidative markers. Moreover, in MCI patients, cognitive function positively correlates with antioxidant levels. This study shows that most of the oxidative changes found in mild AD patients are already present in the MCI group, and that progression to AD might be accompanied by antioxidant depletion.