Bassem Charfeddine

Folate and Homocysteine in the Cerebrospinal Fluid of Patients with Alzheimer’s Disease or Dementia: A Case Control Study

Background: Amyloid deposition in the brain is an early event in Alzheimer’s disease (AD), but a dysfunction of the blood-brain barrier or a disturbance in the metabolism of folate and homocysteine (Hcy) may affect the development of dementia. We investigated if the concentrations of folate and Hcy would be modified in cerebrospinal fluid (CSF) of clinically diagnosed AD patients. Methods: We included 70 AD patients, 33 patients with another type of dementia (nAD) and 30 age-matched control subjects. Plasma Hcy was assayed as well as Hcy, folate, Aβ1-42 and T-tau in CSF. We used ANOVAs for comparison between groups, and then pairwise comparisons by Wilcoxon tests with Bonferroni-corrected p values. Correlations were tested with the Spearman’s rank test. Results: Levels of Aβ1-42, T-tau and folates in CSF were significantly different between groups, but not Hcy. In addition, the average folate in CSF was lower in AD patients compared with controls (18.7 ± 2.4 vs. 20.3 ± 1.7 nmol/l, Bonferroni-corrected p value < 0.02). There was no correlation between Aβ1-42 or T-tau and folate or Hcy in CSF, regardless of the group. In the AD group, there was a significant inverse correlation between Hcy and folate in CSF (ρ = –0.63, p < 0.0001), whereas in the nAD group, a significant correlation was found for Hcy between plasma and CSF (ρ = 0.59, p < 0.0005). Conclusion: The concentration of folate in CSF was found to be decreased in AD patients. These findings support the hypothesis of a possible role of folate in the onset or worsening of AD.

Evaluation of Cerebrospinal Fluid Tau/Beta-Amyloid(42) Ratio as Diagnostic Markers for Alzheimer Disease

Background: Alzheimer’s disease (AD) is the leading cause of dementia. Currently, no definitive diagnostic test for AD exists. Cerebrospinal fluid (CSF) concentrations of amyloid β (Aβ1-42) peptides and total tau proteins (T-tau) may serve as biomarkers for AD. Aim: The objective of this study was to investigate the usefulness of CSF Aβ1-42 and T-tau analyses in the diagnosis of AD with Tunisians. Methods: We focused on three groups originating from Central Tunisian that matched in age (range 48–85): healthy controls (n = 53), AD patients (n = 93) and non-Alzheimer (nAD) dementia (n = 35) patients. Aβ1-42 and T-tau levels were measured in CSF by sandwich enzyme-linked immunosorbent assay. Results: The ratio of T-tau/Aβ1-42 at baseline yielded a sensitivity of 85.3% for detection of AD and the specificity was 84.8% to differentiate controls and nAD dementia. Conclusion: Our findings confirm the use of T-tau/Aβ1-42 ratio in the discrimination of AD patients from all other patients.

CSF β-amyloid 1–42 and tau in Tunisian patients with Alzheimer's disease: The effect of APOE ɛ4 allele

Alzheimers disease (AD) is the leading cause of dementia. Currently, no definitive diagnostic test for AD exists. An accurate, convenient and objective test to detect AD is urgently needed for efficient drug development and effective clinical use of emerging therapies. The aim of the present work is to investigate the usefulness of cerebrospinal fluid (CSF) beta-amyloid protein (Abeta1-42) and total tau protein (t-tau) analyses in the diagnosis of AD and whether apolipoprotein E (ApoE) epsilon4 allele is a factor for AD affecting Tunisian people. Abeta1-42 and t-tau levels were measured in CSF from AD patients (n=73), non-Alzheimer dementia (nAD, n=35) and healthy controls (HC, n=38) by sandwich enzyme-linked immunosorbent assay. Abeta1-42 levels were decreased and t-tau increased in AD patients. The combination of Abeta1-42 and t-tau at baseline yielded a sensitivity of 87.4% for detection of AD. The specificities were 97.3% for controls and 82.7% for other dementia. The ApoE epsilon4 allele frequency (29.5%) was significantly higher in the AD patients than in the nAD patients (17.1%) or in the control groups (9.5%). AD patients carrying ApoE epsilon4 allele had lower Abeta1-42 (p<0.001) levels than those without a epsilon4 allele. The combination of t-tau and Abeta1-42 is a robust and reliable assay that may be useful in discriminating cases at risk for AD such as ApoE epsilon4 allele carriers from nAD patients or from age-matched control subjects.

-1154G/A and -2578C/A polymorphisms of the vascular endothelial growth factor gene in Tunisian Alzheimer patients in relation to β-amyloid (1-42) and total tau protein

Recent evidences indicate that polymorphisms within the promoter region of the vascular endothelial growth factor (VEGF) gene may elevate the risk for Alzheimers disease (AD). To further investigate, we have analyzed association between promoter polymorphisms of the VEGF gene in 93 AD patients and age and sex matched 113 controls from Tunisian population. The distribution of genotype and allele frequencies of the VEGF (-2578C/A) and (-1154G/A) polymorphisms did not differ significantly between AD and control groups (p>0.05). In the subgroup of ApoE varepsilon4 carriers, the -2578A was observed to be significantly higher in the AD patients than in the control individuals. After adjusting the data by gender, age and the ApoE varepsilon4 status using logistic regression, the -2578A allele was found to increase the risk for sporadic AD by 1.7-fold. The present study provides the evidence that the -2578A allele may be associated with the development of AD in the individuals with ApoE varepsilon4 allele. In addition, AD patients carrying the -2578A allele had lower Abeta42 (p=0.029) levels than those without this allele, particularly in subjects with ApoE varepsilon4 allele.

Polymorphism in apoA1 Influences High-Density Lipoprotein Cholesterol Levels but Is Not a Major Risk Factor of Alzheimer’s Disease

Background: Apolipoprotein A1 (apoA1) is the major apolipoprotein constituent of the high-density lipoprotein (HDL) and is involved in reverse cholesterol transport. Variation in the apoA1 gene might influence the function of the protein and, thus, brain cholesterol metabolism, leading to an increased risk for Alzheimer’s disease (AD). Aim: In the current report, we investigated the role of the functional apoA1 polymorphism (–75 G/A) as a genetic risk factor for AD in a Tunisian population. Methods: 173 AD patients and 150 healthy controls were studied. Results: No association was found between this genetic variation in apoA1 gene and the risk of AD. The presence of the (–75 G/A) A allele appeared, however, to be associated with lower levels of cerebrospinal fluid Aβ42 and HDL cholesterol levels in sera. Conclusion: Our data support the observation that apoA1 polymorphism influences cholesterol metabolism and Aβ42 deposition in the brain.

Inhibition of protein glycation, antioxidant and antiproliferative activities of Carpobrotus edulis extracts.

Carpobrotus edulis is an important South African medicinal plants used as a food and therapeutic agent in traditional medicine. The aim of this study was to determine the phytochemical content, antioxidant, antiglycation and cytotoxic effect against Human Colon Cancer Cell Line (HCT-116) of aqueous and ethanol-water (1:1v/v) extracts of Carpobrotus edulis.The content of total phenolics and flavonoids in aqueous and ethanol-water extract were 151.99μg and 66.35μg gallic acid equivalents/mg of dry extract, and 38.84μg and 21.96μg quercetin/mg of dry extract, respectively. Furthermore, phenolic compositions analysis indicated the presence of seven majority compounds including sinapic acid, ferulic acid, luteolin7-o-glucoside, hyperoside, isoquercitrin, ellagic acid and isorhamnetin 3-O-rutinoside. The ethanol-water extract (100-1000μg/mL) showed better antioxidant activity than aqueous extract. Furthermore, Carpobrotus edulis extracts, especially ethanol-water extract significantly inhibited the formation of fluorescent advanced glycation end products, prevented oxidation-induced protein damage and exhibited a cytotoxic effect against HCT116 cells, with a significant decrease in cell viability after 24h of incubation. The results obtained suggest that the Carpobrotus edulis extracts could be used as an easily accessible source of natural antioxidants and as potential phytochemicals against protein glycation and colon cancer.

Effect of ultrasonic degradation of hyaluronic acid extracted from rooster comb on antioxidant and antiglycation activities.

Abstract Content: Recently, low-molecular-weight hyaluronic acid (LMWHA) has been reported to have novel features, such as free radical scavenging activities, antioxidant activities and dietary supplements. Objective: In this study, hyaluronic acid (HA) was extracted from rooster comb and LMWHA was obtained by ultrasonic degradation in order to assess their antioxidant and antiglycation activities. Materials and methods: Molecular weight (Mw) and the content of glucuronic acid (GlcA) were used as the index for comparison of the effect of ultrasonic treatment. The effects on the structure were determined by ultraviolet (UV) spectra and Fourier transform infrared spectra (FTIR). The antioxidant activity was determined by three analytical assays (DPPH, NO and TBARS), and the inhibitory effect against glycated-BSA was also assessed. Results: The GlcA content of HA and LMWHA was estimated at about 48.6% and 47.3%, respectively. The results demonstrate that ultrasonic irradiation decreases the Mw (1090–181 kDa) and intrinsic viscosity (1550–473 mL/g), which indicate the cleavage of the glycosidic bonds. The FTIR and UV spectra did not significantly change before and after degradation. The IC50 value of HA and LWMHA was 1.43, 0.76 and 0.36 mg/mL and 1.20, 0.89 and 0.17 mg/mL toward DPPH, NO and TBARS, respectively. Likewise LMWHA exhibited significant inhibitory effects on the AGEs formation than HA. Discussion and conclusion: The results demonstrated that the ultrasonic irradiation did not damage and change the chemical structure of HA after degradation; furthermore, decreasing Mw and viscosity of LMWHA after degradation may enhance the antioxidant and antiglycation activity.

Characterization, antioxidant and antiglycation properties of polysaccharides extracted from the medicinal halophyte Carpobrotus edulis L

In this study, Box-Behnken design was used to optimize the ultrasonic extraction of Carpobrotus edulis polysaccharides (CEP), and the effect of time, extraction temperature and water to material ratio was evaluated. Optimum conditions were 1.77h, 78.0°C and 33.04mL/g to improved CEP yield (7.84%), which is in good agreement with the predicted yield 7.77%. Then, the physico-chemical, antioxidant and antiglycation properties of optimized CEP were studied, and the total sugar and galacturonic acid content were 89.7 and 63.2%, respectively. The composition of neutral monosaccharide was arabinose, xylose, rhamnose and mannose in the molar percentage of 71.84, 14.80, 8.57, and 4.79%, respectively. In addition, (1H, and 13C) NMR and FTIR analyses confirmed the presence of uronic acids in the free and methyl ester forms with a degree of esterification of 31.27%. Therefore, this finding showed that CEP is a low methoxyl pectic polysaccharide, with an average molecular weight about 65,000g/mol. Finally, the results indicated that CEP presents strong antioxidant activities in vitro (DPPH, chelating ability and reducing power), and significantly inhibits lipid peroxidation and the formation of fluorescent advanced glycation end products in glucose-BSA system model.

7β-hydroxycholesterol-induced cell death, oxidative stress, and fatty acid metabolism dysfunctions attenuated with sea urchin egg oil

Some oxysterols resulting either from enzymatic oxidation or autoxidation of cholesterol are associated with age-related diseases including neurodegenerative diseases. Among these oxysterols, 7β-hydroxycholesterol (7β-OHC) is often found at increased levels in patients. It is therefore important to identify molecules or mixtures of molecules to prevent 7β-OHC-induced side effects. Consequently, murine oligodendrocytes (158N) were cultured in the absence or presence of 7β-OHC (20 μg/mL, 24 h) with or without a natural oil extracted from sea urchin (Paracentrotus lividus) eggs known for its biological activity. Firstly, the chemical composition of this oil was determined using 31P NMR and GC-MS. Secondly, this oil was used to reduce 7β-OHC-induced side effects. To this end, the oil (160 μg/mL) was added to the culture medium of 158N cells 2 h before 7β-OHC. The effects of 7β-OHC with or without the oil on cell viability were studied with the MTT test. Photometric methods were used to analyze antioxidant enzyme activities, superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as the generation of lipid peroxidation products (malondialdehyde (MDA), conjugated dienes (CDs)) and protein oxidation product (carbonylated proteins (CPs)). Gas chromatography was used to determine the fatty acid profile. With 7β-OHC, an induction of cell death associated with oxidative stress (alteration of GPx and SOD activities) was observed; an overproduction of lipid peroxidation products (MDA and CDs) and CPs was also revealed. Sea urchin egg oil attenuated 7β-OHC-induced cytotoxicity: 7β-OHC-induced cell death was reduced, GPx and SOD activities were normalized, and lower levels of MDA, CDs and CPs were produced. In addition, whereas a disturbed fatty acid profile was observed with 7β-OHC, similar fatty acid profiles were found in control cells and in cells cultured with 7β-OHC associated with sea urchin egg oil. These data demonstrate the protective activities of sea urchin egg oil against 7β-OHC-induced side effects on 158N cells, supporting the concept that this oil may have benefits in the prevention of neurodegenerative diseases.

[Maroteaux-Lamy syndrome: a case report].

The Maroteaux-Lamy disease, or mucopolysaccharidosis type VI is an inherited metabolic disorder severe and rare. It is caused by a deficiency of the enzyme arylsulfatase B. It is characterized by a heterogeneous clinical, radiological and genetic. We report the case of a Maroteaux-Lamy syndrome of in a child aged 7 years whose diagnosis was suspected clinically by the combination of a dysmorphic syndrome, a failure to thrive not harmonious, hepatomegaly and normal intelligence. Radiological exams have objectified dysostosis multiplex. Biochemical analysis of urine showed the abnormal presence of dermatan sulfate. The determination of leukocyte enzyme activity confirmed the diagnosis by showing arylsulfatase B deficiency. Hence the diagnosis of syndrome Maroteaux-Lamy in its mild form (type B) was selected.