Jeanne Ngogang

Association of Variants at BCL11A and HBS1L-MYB with Hemoglobin F and Hospitalization Rates among Sickle Cell Patients in Cameroon

Background Genetic variation at loci influencing adult levels of HbF have been shown to modify the clinical course of sickle cell disease (SCD). Data on this important aspect of SCD have not yet been reported from West Africa. We investigated the relationship between HbF levels and the relevant genetic loci in 610 patients with SCD (98% HbSS homozygotes) from Cameroon, and compared the results to a well-characterized African-American cohort. Methods and Findings Socio-demographic and clinical features were collected and medical records reviewed. Only patients >5 years old, who had not received a blood transfusion or treatment with hydroxyurea were included. Hemoglobin electrophoresis and a full blood count were conducted upon arrival at the hospital. RFLP-PCR was used to describe the HBB gene haplotypes. SNaPshot PCR, Capillary electrophoresis and cycle sequencing were used for the genotyping of 10 selected SNPs. Genetic analysis was performed with PLINK software and statistical models in the statistical package R. Allele frequencies of relevant variants at BCL11A were similar to those detected in African Americans; although the relationships with Hb F were significant (p <.001), they explained substantially less of the variance in HbF than was observed among African Americans (∼ 2% vs 10%). SNPs in HBS1L-MYB region (HMIP) likewise had a significant impact on HbF, however, we did not find an association between HbF and the variations in HBB cluster and OR51B5/6 locus on chromosome 11p, due in part to the virtual absence of the Senegal and Indian Arab haplotypes. We also found evidence that selected SNPs in HBS1L-MYB region (HMIP) and BCL11A affect both other hematological indices and rates of hospitalization. Conclusions This study has confirmed the associations of SNPs in BCL11A and HBS1L-MYB and fetal haemoglobin in Cameroonian SCA patients; hematological indices and hospitalization rates were also associated with specific allelic variants.

First-line antiretroviral therapy and dyslipidemia in people living with HIV-1 in Cameroon: a cross-sectional study

BackgroundData on lipid profile derangements induced by antiretroviral treatment in Africa are scarce. The aim of this study was to determine the prevalence and characteristics of lipid profile derangements associated with first-line highly active antiretroviral therapy (ART) among Cameroonians living with human immunodeficiency virus (HIV) infection.MethodsThis cross-sectional study was conducted between November 2009 and January 2010, and involved 138 HIV patients who had never received ART (ART-naive group) and 138 others treated for at least 12 months with first line triple ART regimens that included nevirapine or efavirenz (ART group). Lipid profile was determined after overnight fast and dyslipidemia diagnosed according to the US National Cholesterol Education Program III criteria. Data comparison used chi-square test, Student t-test and logistic regressions.ResultsThe prevalence of total cholesterol ≥ 200 mg/dl was 37.6% and 24.6% respectively in ART group and ART-naive groups (p = 0.019). The equivalents for LDL-cholesterol ≥ 130 mg/dl were 46.4% and 21% (p ≤ 0.001). Proportions of patients with total cholesterol/HDL-cholesterol ratio ≥ 5 was 35.5% in ART group and 18.6% in ART-naive group (p ≤ 0.001). The distribution of HDL-cholesterol and triglycerides was similar between the two groups. In multivariable analysis adjusted for age, sex, body mass index, CD4 count and co-infection with tuberculosis, being on ART was significantly and positively associated with raised total cholesterol, LDL-cholesterol and TC/HDL cholesterol. The adjusted odd ratios (95% confidence interval, p-value) ART-treated vs. ART-naïve was 1.82 (1.06-1.12, p = 0.02) for TC ≥ 200 mg/dl; 2.99 (1.74-5.15), p < 0.0001) for LDL-cholesterol ≥ 130 mg/dl and 1.73 (1.04-2.89, p = 0.03) for TC/HDL-cholesterol ≥ 5.ConclusionsFirst-line antiretroviral therapy that includes nonnucleoside reverse transcriptase inhibitors is associated with pro-atherogenic adverse lipid profile in people with HIV-1 infection compared to untreated HIV-infected subjects in Yaounde. Lipid profile and other cardiovascular risk factors should be monitored in patients on such therapy so that any untoward effects of treatments can be optimally managed.

The Co-Inheritance of Alpha-Thalassemia and Sickle Cell Anemia Is Associated with Better Hematological Indices and Lower Consultations Rate in Cameroonian Patients and Could Improve Their Survival

Background Co-inheritance of α-thalassemia was reported to be associated with a delayed age of disease onset among Cameroonian Sickle Cell Anemia (SCA) patients. The present study aimed to explore the correlation between α-thalassemia, hematological indices, and clinical events in these patients. Methods and Findings We studied 161 Cameroonian SCA patients and 103 controls (59.1% HbAA) with median ages of 17.5 and 23 years. RFLP-PCR was used to confirm SCA genotype and to describe haplotypes in the HBB-like genes cluster. Multiplex Gap-PCR was performed to investigate the 3.7 kb α-globin gene deletions. SNaPshot PCR, capillary electrophoresis and cycle sequencing were used for the genotyping of 10 SNPs in BCL11A, HMIP1/2, OR51B5/6 and HBG loci, known to influence HbF levels. Generalised linear regression models adjusted for age, sex and SNPs genotypes was used to investigate effects of α-thalassemia on clinical and hematological indices. The median rate of vaso-occlusive painful crisis and hospitalisations was two and one per year, respectively. Stroke was reported in eight cases (7.4%). Benin haplotype was the most prevalent (66.3%; n = 208 chromosomes). Among patients, 37.3% (n = 60) had at least one 3.7 kb deletion, compared to 10.9% (n = 6) among HbAA controls (p<0.001). Among patients, the median RBC count increased with the number of 3.7 kb deletions [2.6, 3.0 and 3.4 million/dl, with no, one and two deletions (p = 0.01)]. The median MCV decreased with the number of 3.7 kb deletion [86, 80, and 68fl, with no, one and two deletions (p<0.0001)], as well as median WBC counts [13.2, 10.5 and 9.8×109/L (p<0.0001. The co-inheritance of α-thalassemia was associated with lower consultations rate (p = 0.038). Conclusion The co-inheritance of α-thalassemia and SCA is associated with improved hematological indices, and lower consultations rate in this group of patients. This could possibly improve their survival and explain the higher proportion of α-thalassemia among patients than controls.

In vitro antioxidant activity of three Piper species.

Reactive oxygen species are known to play a role in numerous pathological conditions, and antioxidants from plant sources have been of great help in modulating this effect. This study assesses the methanolic exttacts of the leaves of three Piper species (Piper guineense Schum and Thonn, Piper nigrum L. and Piper umbellatum L.) (Piper-aceae) for their polyphenolic concentration and free radical scavenging activity. The Folin-Ciocalteu method was used to assess the polyphenolic concenttation while the reducing power, l,l-diphenyl-2-picrylhydrazyl (DPPH), Superoxide radical, hydroxyl radical, nitric oxide scavenging and metal chelating activities were employed in studying the radical scavenging activity of the extracts. All three spices exhibited a marked polyphenolic concentration and dose dependent free radical scavenging activity. The free polyphenolic concentration of the three spices was in the order P. umbellatum(15.9 ± 1.9 mg/g) > P. guineense(12.6 ± 0.3 mg/g) > P. nigrum(9.8 ± 0.8). The three Piper extracts exhibited a 79.8-89.9% scavenging effect on DPPH, an 85.1-97.9% scavenging effect on nitric oxide at a dose level of 10 mg/ml and a 47.1-51.6% scavenging effect on Superoxide radical at a dose level of 8 mg/ml extraction. Piper extracts also exhibited a 57-76.1% scavenging effect on hydroxyl radical at 5 mg/ml, a 0.4-0.6 reducing power and an 88.3-93.9% metal chelating activity at a dose level of 8 mg/ml of extract. Thus, these Piper species can play a role in the modulation of free radical induced disorders.

In vitro cytotoxicity and antioxidant activities of five medicinal plants of Malvaceae family from Cameroon

The potential antiproliferative and antioxidant activities of extracts from five medicinal plants from Cameroon were evaluated in vitro on HepG-2 cells. The results showed the significant decrease of the viability of the cells in a concentration-dependent manner. According to the IC(50) obtained, the extracts of S. acuta (461.53±0.23) and U. lobata (454.93±0.12) showed significant antiproliferative activity. At fixed concentration (250μgmL(-1)), extracts demonstrated higher antiproliferative activity (67.05%; 65.42%), (52.62%; 56.64%) and (32.98%; 36.85%) respectively during 24, 48 and 72h. Extracts of S. cordifolia and V. album demonstrated significant antiproliferative property after 48h while S. rhombifolia exhibited weak cytotoxicity. The results of the antioxidant properties showed that theses extracts induced significantly increase of SOD, CAT and GsT activity after 48h. Taken together, the results extracts showed that of S. acuta and U. lobata may be a promising alternative to synthetic substances as natural compound with high antiproliferative and antioxidant activities.

Antioxidant Effect of Herbs and Spices on Copper Mediated Oxidation of Lower and Very Low Density Lipoprotein

Abstract Aim The present study investigates the antioxidant effect of two extracts (hydrolyzed and non-hydrolyzed) of five herbs and eight spices in the prevention of LDL + VLDL oxidation promoted by cupric ion. Methods The polyphenolic concentrations of these extracts were measured using Folin-Ciocalteu reagent. The antioxidant quality was analyzed by the determination of lag-time, concentration of polyphenol that will inhibit 50% of oxidation of LDL + VLDL (IC 50 ) and phenol antioxidant index (PAOXI). Results The hydrolyzed extracts had significant higher polyphenol concentration, longer lag-time, lower IC 50 and higher PAOXI than the non-hydrolyzed extracts ( P Conclusion The reaction rate and concentration of conjugated diene formed suggested that all the extracts had similar reaction mechanism in the prevention of copper mediated LDL + VLDL oxidation.

Syzyguim guineense Extracts Show Antioxidant Activities and Beneficial Activities on Oxidative Stress Induced by Ferric Chloride in the Liver Homogenate

The aim of this study was to determine the in vitro antioxidant activity, free radical scavenging property and the beneficial effects of extracts of various parts of Syzygium guineense in reducing oxidative stress damage in the liver. The effects of extracts on free radicals were determined on radicals DPPH, ABTS, NO and OH followed by the antioxidant properties using Ferric Reducing Antioxidant Power assay (FRAP) and hosphomolybdenum (PPMB). The phytochemical screening of these extracts was performed by determination of the phenolic content. The oxidative damage inhibition in the liver was determined by measuring malondialdehyde (MDA) as well as the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase. Overall, the bark extract of the ethanol/water or methanol showed the highest radical scavenging activities against DPPH, ABTS and OH radicals compared to the other extracts. This extract also contained the highest phenolic content implying the potential contribution of phenolic compounds towards the antioxidant activities. However, the methanol extract of the root demonstrated the highest protective effects of SOD and CAT against ferric chloride while the hydro-ethanol extract of the leaves exhibited the highest inhibitory effects on lipid peroxidation. These findings suggest that antioxidant properties of S. guineense extracts could be attributed to phenolic compounds revealed by phytochemical studies. Thus, the present results indicate clearly that the extracts of S. guineense possess antioxidant properties and could serve as free radical inhibitors or scavengers, acting possibly as primary antioxidants. The antioxidant properties of the bark extract may thus sustain its various biological activities.

Fruits and barks extracts of Zanthozyllum heitzii a spice from Cameroon induce mitochondrial dependent apoptosis and Go/G1 phase arrest in human leukemia HL-60 cells

BackgroundZanthoxylum heitzii is a spice used to prepare several dishes and to treat tumors, syphilis, malaria, cardiac palpitations, urogenital infections in the west region of Cameroon, but the antitumor mechanisms and chemical composition are not yet investigated.This study was aimed to determine the antiproliferative effects of four extracts from the fruits and barks of Zanthoxyllum heitzii (Rutaceae) on apoptosis in human promyelocytic cells, their mechanisms and the chemical composition. The 3-(4, 5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the fifty percent inhibition (IC50) concentration of the cell lines after treatment. The effect on morphology was observed using a light or fluorescence microscopy. The rate of apoptosis and the cell cycle were measured using flow cytometry (FCM). The phytochemical analysis of the extract was carried with HPLC/MS methods.ResultsThe phytochemical analysis of the extracts indicated the presence of four known polyphenols (Syringic acid, Juglon, Luteolin and Myricetin) in both fruits and barks of Z. heitzii but in different quantities. Syringic acid and Myricetin concentrations were between 17-21 fold higher in the fruits than the stem bark. Rhamnetin (393.35 μg/mL) and Oleuropein (63.10 μg/mL) were identified only in the stem barks of Z. heitzii. Among the four extracts tested for cytotoxicity properties, only the methanol extract of fruits and barks significantly inhibited cell proliferation of HL-60 cells with IC50 value of 20 μg/mL and 12 μg/mL respectively. HL-60 cells treated with Z. heitzii extracts significantly produced reactive oxygen species (ROS) with concurrent loss of mitochondrial membrane potential (MMP). Modifications in the DNA distribution and enhanced of G1/G0 phase cell cycle arrest were observed in a concentration dependent manner.ConclusionsPolyphenols from Z. heitzii plant exert inhibitory effect on HL-60 cells through the reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential and cell cycle destabilization.

Protective effects of stem bark of Harungana madgascariensis on the red blood cell membrane

BackgroundAnemia is a condition that has multiple origins. One such origin is the destruction of red blood cells’ (RBCs) membrane induced by free radicals. Treatment of anemia could therefore be enhanced by the use of free radicals’ scavengers potentially found in some medicinal plants. In this study, the protective effect of Harungana madagascariensis on the RBCs’ membrane physiology was investigated in vitro and in vivo.MethodsIn vitro hemolytic anemia was induced by incubation of fresh human RBCs with carbontetrachloride (CCl4) in Olive oil (Oo). Relaxation times of protons excited at 20 MHz (Carr-Purcell-Meiboom-Gill pulse sequence) in the absence or presence of paramagnetic Mn2+ ions (T2i for “extracellular” water and T2a for “intracellular” water, respectively) were determined at several temperatures (25–37°C) via Nuclear Magnetic Resonance (NMR) on a Bruker Minispec spectrometer. Water exchange times (Te) were consequently calculated using the Conlon-Outhred equation: 1/Te = (1/T2a) – (1/T2i). Morphological characteristics (mean cell volume, V, and cell surface area, A) were determined by photonic microscopy and the RBCs’ diffusional water permeability (Pd) was calculated as Pd = (1/Te)*(Va/A), where Va is the aqueous volume in the RBC and is about 0.7 of the cell volume (V). The activation energy of the diffusional process (Ea) for the respective temperature range was estimated using the Arrhenius modified equation k = A(T/T0)n*e-Ea/RT. Inhibition of the water diffusion induced by incubation with para-chloro-mercuribenzoic acid (PCMB) at 25, 30 and 37°C was calculated as I(%) = [(Pd control – Pd sample)/Pd control]*100.To investigate the protective influence of the extract on the RBC membrane, inhibition of the water permeability was evaluated on membranes pre-incubated with the Harungana madagascariensis extract. Male rats were used in in vivo investigations. Malondialdehyde (MDA) and cholesterol in the RBC membrane were estimated by induction of lipid peroxidation while the antioxidant properties of catalase (CAT) and superoxide dismutase (SOD) on the membrane were evaluated in regard to their antioxidant properties on the membrane.ResultsT2a significantly decreased at each temperature. Te results were higher in both RBCs and RBCs + extract groups incubated with PCMB compared to non-incubated controls, but differences were not statistically significant. A high percentage (73.81 ± 7.22) of RBCs pre-incubated with the extract presented the regular biconcave shape. Inhibition by PCMB of the RBCs’ membrane water permeability was increased at 30°C and decreased in the presence of extract (25°C and 37°C), while Ea decreased from 30.52 ± 1.3 KJ/mol to 25.49 ± 1.84 KJ/mol. Presence of the Harungana madagascariensis extract normalized the SOD and CAT activities as well as the MDA and membrane cholesterol concentrations altered by the CCl4-induced oxidative stress.ConclusionHarungana madagascariensis could protect the RBCs’ membrane through its antioxidative properties.

Acceptability of Prenatal Diagnosis by a Sample of Parents of Sickle Cell Anemia Patients in Cameroon (Sub-Saharan Africa)

Little is known about attitudes of parents of Sickle Cell Anemia patients in sub-Saharan Africa regarding prenatal genetic diagnosis and termination of an affected pregnancy. In this study, structured face-to-face interviews were conducted with a sample of 130 parents in Cameroon that had at least one living child with Sickle Cell Anemia. The majority of participants lived in urban areas (89%), were female (80%), Christian (93%), married (60.2%) in monogamous households (81.1%), were employed (61.7%), and had at least a secondary or tertiary education (82%). The majority of parents accepted the principle of prenatal genetic diagnosis for Sickle Cell Anemia (89.8%) and termination of pregnancy (62.5%). Acceptance of the principle of pregnancy termination increased with unemployment (p < .01) and single marital status (p < .05). The results of this study suggest Cameroonian parents with children affected with Sickle Cell Anemia generally accept the principles of prenatal diagnosis and in some cases termination of a pregnancy affected with Sickle Cell Anemia. Additional findings, policy and practice implications, and research recommendations are presented.