Search Results (132)

Objective: To characterize the profiles of resistance mutations to HIV reverse transcriptase inhibitors in Gabon. Design: Cross-sectional study conducted over 37 months, from October 2019 to October 2022, at the IST/HIV/AIDS Reference Laboratory, a reference center for the biological monitoring of people living with the human immunodeficiency virus (PWHIV) in Gabon. Methods: Plasma from 666 PWHIV receiving antiretroviral treatment was collected, followed by RNA extraction, amplification, and reverse transcriptase gene sequencing. Statistical analyses were performed using Stata^® 14.0 software (USA). Results: Six hundred and sixty-six (666) PWHIV plasma collected from 252 male and 414 female patients were analyzed and 1654 mutations were detected in 388 patients, including 849 (51.3%) associated with nucleoside reverse transcriptase inhibitors (NRTIs) and 805 (48.7%) with non-nucleoside reverse transcriptase inhibitors (NNRTIs). Three of the most prescribed treatment regimens were associated to the appearance of both NRTIs and NNRTIs resistance mutations: TDF + 3TC + EFV (24.02%; 160/666); TDF + FTC + EFV) (17.2%; 114/666) and AZT + 3TC + EFV (14.6%; 97/666). Additionally, stage 3 of CD4 T-lymphocyte deficiency, the higher viral load, and treatment duration are risk factors influencing the appearance of virus mutations. Also, treatment containing TDF-3TC + DTG is more protective against mutations. Conclusions: Drug resistance mutations are common in Gabon and compromise the efficacy of ART. Further study must search for other causes of therapeutic failure in Gabon in PWHIV. Full article

Decoctions of stem barks from Aucoumea klaineana, Canarium schweinfurthii, Pentadesma butyracea and Scorodophloeus zenkeri are used against affections of irritable bowel syndrome in Gabonese traditional medicine. In the present study, we aim to determine whether the bark polysaccharides may contribute to the activity of these plants against the symptoms of gastrointestinal disorders. To this end, we investigated the structure and the pharmacological activity of polysaccharides extracted from their stem barks. The pectic and hemicellulose polysaccharides were isolated, and their sugar compositions were determined by gas chromatography. In addition, analysis by MALDI-TOF mass spectrometry of oligosaccharides released after digestion with an endo-xylanase indicated that glucuronoarabinoxylans are the main hemicellulose of stem barks. We then evaluated the influence of the polysaccharide fractions on the spontaneous contractile activity of rat ileal smooth muscle and the cholinergic system. Spasmolytic activity of pectic fractions from all stem barks, as well as lemon polygalacturonic acid, were observed, indicating that these extracts exhibit a myorelaxant activity. In contrast, the bark hemicellulose fractions, as well as commercially available beechwood glucuronoxylan and wheat arabinoxylan, were demonstrated to be able to increase the basal contractile activity of smooth muscle. These data show that, beyond physicochemical effects affecting the bowel water content, plant polysaccharides have also an impact on the spontaneous smooth muscle contractility, the main mechanism involved in the pathophysiology of gastrointestinal disorders. Full article

This study offers a detailed comparative analysis of the reflexes of Proto-Bantu noun class prefixes within nine Gabonese languages belonging to the B50, B60, and B70 groups of Guthrie’s referential inventory of the Bantu languages. Genealogically speaking, all of them are part of the Kwilu-Ngounie subclade of the Bantu family’s West-Coastal Bantu branch. Starting out from a robust dataset comprising over 4000 lexical items collected through fieldwork and existing descriptions, the Comparative Method is used to distinguish changes in noun class morphology due to regular sound shifts from those emerging from analogical reanalysis and levelling. The comparative study shows a systematic reduction and reorganization of the inherited Proto-Bantu noun class system, notably the loss of classes 12/13 and 19 across all languages, variable retention and loss of classes 7/8 and 11, and complex patterns of reshuffling involving classes 5, 9/10, and 1/2. Key innovations, potentially reinforcing lexicon-based hypotheses of phylogenetic subgrouping within Kwilu-Ngounie, include the development of a class 7 allomorphy conditioned by stem-initial segments in the B50 languages and the emergence of vocalic prefixes restricted to the B60 and B70 languages. Full article

This paper aims to develop a rheological model with fewer parameters that accurately describes the primary and secondary creep behavior of wood materials. The models studied are grounded in Riemann–Liouville fractional calculus theory. A comparison was conducted between the constant-order fractional Zener model and the variable-order fractional Maxwell model, with four parameters each. Using experimental creep data from four-point bending tests on two tropical wood species, along with an optimization algorithm, the variable-order fractional model demonstrated greater effectiveness. The selected fractional derivative order, modeled as a linearly increasing function of time, helped to elucidate the internal mechanisms in the wood structure during creep tests. Analyzing the parameters of this order function enabled an interpretation of their physical meanings, showing a direct link to the material’s mechanical properties. The Sobol indices have demonstrated that the slope of this function is the most influential factor in determining the model’s behavior. Furthermore, to enhance descriptive performance, this model was adjusted by incorporating stress non-linearity to account for the effects of the variation in constant loading level in wood. Consequently, this new formulation of rheological models, based on variable-order fractional derivatives, not only allows for a satisfactory simulation of the primary and secondary creep of wood but also provides deeper insights into the mechanisms driving the viscoelastic behavior of this material. Full article

The study of vibration isolation devices has become an emerging area of research in view of the extensive damage to buildings caused by earthquakes. The ability to effectively isolate seismic vibrations and maintain the stability of a building is thus addressed in this paper, which evaluates the effect of horizontal ground excitation on the response of a structure isolated by a coupled isolation system consisting of a non-linear damper (QZS) and a friction pendulum system (FPS). A single-degree-of-freedom system was used to model structures whose bases are subjected to seismic excitation in order to assess the effectiveness of the QZS–FPS coupling in reducing the structural response. The results obtained revealed significant improvements in structural performance when the QZS–FPS system uses a damper of optimum stiffness. A 30% reduction in displacement was recorded compared with QZS alone for two signals, one harmonic and the other stochastic. The response of the QZS–FPS system with soft stiffness to a harmonic pulse reveals amplitudes reaching around eight times those of the pulse at low frequencies and approaching zero at high frequencies. In comparison, the rigid QZS–FPS coupling has amplitudes 0.9 and 3.5 times higher than those of the harmonic signal. Thus, the resonance amplitudes observed for the QZS–FPS system are lower than those reported in other studies. This analysis highlights the performance differences between the two types of stiffness in the face of harmonic pulses, underlining the importance of the choice of stiffness in vibration management applications. The stochastic results show that on both hard and soft soils, the new QZS–FPS system causes structures to vibrate horizontally with maximum amplitudes of the order of 0.003 m and 0.007 m respectively. So, QZS–FPS coupling can be more effective than all other isolators for horizontal ground excitation. In addition, the study demonstrated that the QZS–FPS combination can offer better control of building vibration in terms of horizontal displacements. Full article

Background: Urogenital schistosomiasis is endemic in Gabon. Our study aimed to detect the prevalence of urinary schistosomiasis and to evaluate the diagnostic performance of the qPCR technique compared to microscopy for the detection of Schistosoma haematobium at the community level in a semi-rural area. Method: A cross-sectional survey was carried out. Urine samples were examined using Urine TICK test strips, a filtration technique, and qPCR. Schistosoma haematobium was detected by targeting the Dra1 gene. Results: The prevalence of urogenital schistosomiasis was determined and the performance of real-time PCR and urine strips was compared with that of urinary filtration. A total of 281 participants were enrolled in the study. The prevalence of urogenital schistosomiasis was increased slightly with the molecular technique (40.9%) compared to microscopy (36.7%), and the hematuria rate with Urine STICK was 33.5%. SAC (5–14 years old), Pre-SAC (>5 years old), and adolescents (15–17 years old) were the most affected group according to, respectively, whatever method was used. qPCR showed good agreement with microscopy, as well as excellent sensitivity (99.03%) and specificity (93.3). There was a good correlation between the number of eggs per 10 mL and the cycle threshold range. Conclusion: These results show the importance of using a combination of diagnostic tools in the surveillance of schistosomiasis, particularly in preschool children, adolescents, women of childbearing age, and chronic and asymptomatic cases. Full article

Background/Objectives: Human papillomavirus (HPV) vaccination is a critical intervention to prevent cervical cancer, especially in settings where screening is limited. In Togo, cervical cancer is the second most common cancer in women. Togo conducted an HPV vaccination campaign for girls aged 9–14 from 27 November to 1 December 2023, followed by introduction of the vaccine into routine immunization. This study aimed to assess regional disparities in vaccination coverage during this campaign. Methods: A cross-sectional study was conducted using data from the nationwide HPV vaccination campaign. The target population included girls aged 9–14, following school and community-based enumeration. The campaign employed school-based, health facility-based, and community-based vaccination strategies. Data were collected via multiple tools, and monitoring was carried out through daily reports and digital tracking. Results: Out of the estimated 654,402 eligible girls, 304,457 (46.5%) were vaccinated. Vaccine coverage varied significantly by region, ranging from 76% in Kara to 15% in Grand Lomé. In-school settings accounted for 91.3% of vaccinations, with the fixed strategy covering 55.4%. In total, 11 districts exceeded 80% vaccine coverage, while 15 districts had <50%. The highest rate of adverse events following immunization was observed in the Maritime region, primarily involving minor symptoms. Conclusion: Although progress was made in HPV vaccination coverage in Togo, regional disparities highlight the need for targeted interventions. Strategies such as expanding vaccine access, enhancing awareness campaigns, and integrating HPV vaccination into routine immunization could improve coverage. Addressing logistical and cultural barriers is also crucial for equitable vaccination, aiming to achieve international benchmarks and reduce HPV-related disease burdens. Further research should explore qualitative factors influencing vaccine acceptance. Full article

This paper explores the effects of the cessation of forest commodity exports and the implementation of an industrialization strategy in Gabon, drawing on traditional theories of regional growth. The creation of the Nkok Special Economic Zone (SEZ) in 2012, accompanied by its strategic location and significant infrastructure investments, illustrates the application of Rosenstein-Rodan’s “Big Push” and Douglass-North’s “export base” theories. These initiatives also led to a polarization process consistent with the work of Perroux and other theorists of unbalanced regional growth. The study assesses the impact of this SEZ on regions external to the SEZ and the macroenvironment during the period 2014–2022. It highlights the industrial and commercial mechanisms that promote agglomeration economies, technological diffusion, the creation of economic connections, and the structuring into “core-periphery” zones, in accordance with the concepts of Hirschman. The results show a strong positive correlation between industrial income, exports (excluding raw materials), and industrial production. However, the ban on the export of wood raw materials led to a negative relationship between industrial income and exports of these products. Furthermore, the local processing of forest products has promoted industrial diversification, generated new products, and gradually increased added value. The process of economic and geographical polarization is described as a transitional phase of imbalances whose long-term implications require in-depth studies, particularly in the context of countries in the South and underdeveloped environments. Full article

The sustainability of coastal environments is becoming a major issue in the face of constantly changing urban populations correlated with anthropogenic activities. As a result, in-depth knowledge is needed to assess the vulnerability of coastal areas in African cities faced with a profusion of solid waste. In Libreville and Lomé, the aim of the study was to carry out a systematic inventory of coastal macrowaste, and to break down and characterize the data collected at 12 sites and 6 sites, respectively. The methodological approach adopted combines documentary research, direct observations and characterization using the MODECOM tool (household waste characterization method) to reveal the widespread presence of macrowaste in the coastal areas of the two towns. With regard to the MODECOM method, the study is based specifically on the sorting of materials according to three granulometric fractions: >100 mm, between 20 and 100 mm, and <20 mm. In addition to the dimensions of the objects, the classification of solid waste according to its nature enabled thirteen (13) categories of macrowaste to be generated. The results show that the quantity of macrowaste inventoried in Libreville was 654.21 kg, while in Lomé the weight of waste collected was 510 kg. On the whole, the proliferation of solid waste is due to physical factors and human activities, especially economic activities and recreational activities, which increase the rate of production. In terms of sustainable material management, the results point to a prosperous future for the biodegradable, non-biodegradable and inert waste streams. Full article

Adolescent idiopathic scoliosis (AIS) is characterized by a curvature of the spine affecting approximately 4% of the pediatric population, and the mechanisms driving its progression remain poorly understood. Whole-exome sequencing of a French-Canadian AIS cohort with severe scoliosis identified rare variants in the PTPRM gene, which encodes Protein Tyrosine Phosphatase μ (PTPµ). However, these rare variants alone did not account for the pronounced reduction in PTPµ at both mRNA and protein levels in severe AIS cases. This led us to investigate epigenetic regulators and the identification of five microRNAs (miR-103a-3p, miR-107, miR-148a-3p, miR-148b-3p, and miR-152-3p) that target PTPRM mRNA. These microRNAs were significantly elevated in plasma from severe AIS patients, and miR-148b-3p was also upregulated in AIS osteoblasts. Phenotypic analysis of bipedal Ptrprm knockout (PTPµ −/−) mice showed increased prevalence and severity of scoliosis, while quadrupedal PTPµ −/− mice did not develop scoliosis, underscoring PTPµ’s role as a disease-modifying factor. Mechanistically, PTPµ deficiency was found to disrupt Gi-coupled receptor signaling in osteoblasts by enhancing the interaction between osteopontin (OPN) and α5β1 integrin, along with increased tyrosine phosphorylation of phosphatidylinositol-4-phosphate 5-kinase type I (PIPKIγ90). These findings provide novel insights into the molecular mechanisms underlying spinal deformity progression in AIS, linking PTPµ depletion to aberrant OPN-α5β1 integrin signaling and highlighting potential therapeutic targets to stop, mitigate, or prevent scoliosis. Full article

This study aimed to determine the prevalence of co-infection with malaria and intestinal parasites and assess its association with anemia in school-aged children from rural and urban settlements in Gabon. This cross-sectional study involved afebrile school children recruited at schools between May and June 2021. Blood and stool samples were collected from participants whose parents or legal guardians provided informed consent to participate in the study. Hemoglobin concentration (Hb) was measured using a HemoCue photometer (HemoCue 201, HemoCue, Angelholm, Sweden). Giemsa-stained blood films were examined to detect malaria parasites and any filarial infections, while the merthiolate-iodine concentration (MIC) method was used to identify intestinal parasitic infections (IPI). A total of four hundred and seventy (470) school-aged children were successfully enrolled in this study. The observed prevalence values were as follows: malaria infection at 69.6%, IPIs at 19.1%, filaria at 5.1%, Schistosoma infection at 15.0%, and anemia at 29.0%. Co-infections of malaria with IPIs, filaria, and Schistosoma were present in 12.3%, 4.7%, and 6.6% of the children, respectively. Malaria and filaria infections were associated with residing in Lastourville city (p < 0.05) and were also correlated with age (p < 0.05), whereas IPIs were associated with male gender and living in the city of Lastourville. Anemia was linked to malaria infection (p < 0.05) and was more prevalent among children living in rural areas. The findings of this study indicate that malaria, IPIs, and Schistosoma infections continue to pose a significant public health problem in the study area, even though only malaria infection appeared to be associated with anemia. Nevertheless, these results highlight the need for implementing control measures to reduce the prevalence of malaria, IPIs, filaria, and Schistosoma, particularly in Lastourville. Full article

(1) Objectives: The burden of SARS-CoV-2 infection in people living with HIV (PLHIV) in Gabon is unknown. (2) Methods: We conducted a cross-sectional seroprevalence study of SARS-CoV-2 immunoglobulin (Ig) G/M antibodies in PLHIV in Libreville from April 2022 to April 2023 after the fourth wave of the pandemic. We used the WANTAI SARS-CoV-2 Ab ELISA targeting the SARS-CoV-2 spike, receptor-binding domain. (3) Results: Among 480 samples tested, the seroprevalence of IgG antibodies to SARS-CoV-2 spike protein was 87.5% (95% confidence interval (CI) 77.7–97.3%). History of SARS-CoV-2 diagnosis, ART treatment, and TCD4 lymphocyte count were not found to be associated with the presence of antibodies against SARS-CoV-2 among the study participants. However, having a detectable viral load (p = 0.0001), being vaccinated (COVID-19 vaccine, p = 0.04), and a history of COVID-19 (p < 0.0001) symptoms were associated with a higher risk of having anti-SARS-CoV-2 antibodies. (4) Conclusions: By early 2023, PLHIV in Gabon had high rates of SARS-CoV-2 seropositivity. To our knowledge, this is the first study to determine the seroprevalence of SARS-CoV-2 antibodies in PLHIV in Gabon. This study provides further evidence of anti-SARS-CoV-2 seroconversion in the absence of any vaccination in a particular target population. The surveillance of diseases of global health concern in PLHIV is crucial to estimate population-level exposure and inform public health responses. Full article

Introduction: Cryptococcal meningitis is a major cause of death in HIV/AIDS patients due to the existence of Cryptococcus neoformans in the central nervous system. Our objective was to evaluate the prevalence of Cryptococcus antigenuria in a population of HIV-infected patients in Libreville, Gabon. Patients and Methods: This study was conducted from April to October 2021 at the Infectious Diseases ward of the Centre Hospitalier Universitaire de Libreville. Hospitalized patients with HIV were included. The detection of cryptococcal antigen (CrAg) in urine was performed using the Pastorex Crypto Plus Kit. Results: Out of the 255 PLHIV, 142 benefited from the CrAg detection. The prevalence of urine CrAg was 24.6% (n = 35). The majority of CrAg+ patients (82.8%; n = 29) were under 55 years old. Almost three-quarters of them (n = 25; 71.4%) had CD4 counts < 200, and 80.0% (n = 28) were at WHO clinical stages III and IV. All patients with neck stiffness at admission had a CrAg positive test. Conclusion: This study showed a non-negligible prevalence of Cryptococcal urinary antigen in HIV-infected patients with neurological symptoms. These data underline the importance of CrAg screening in routine care for better management of PLHIV. Full article

Malaria poses a serious global health problem, with half the world population being at risk. Regular screening is crucial for breaking the transmission cycle and combatting the disease spreading. However, current diagnostic tools relying on blood samples face challenges in many malaria-epidemic areas. In the present study, we demonstrate the detection of the malaria-causing Plasmodium parasite in non-invasive saliva samples (N = 61) from infected individuals by combining a DNA-based Rolling-circle-Enhanced-Enzyme-Activity-Detection (REEAD) sensor system with a chemiluminescence readout that could be detected with an in-house-developed affordable and battery-powered portable reader. We successfully transferred the technology to sub-Saharan Africa, where the malaria burden is high, and demonstrated a proof of concept in a small study (N = 40) showing significant differences (p < 0.00001) between malaria-positive individuals (N = 33) and presumed asymptomatic negative individuals (N = 7) all collected in Gabon. This is the first successful application of the REEAD sensor system for the detection of malaria in saliva in a high-epidemic area and holds promise for the potential future use of REEAD for malaria diagnosis or surveillance based on non-invasive specimens in sub-Saharan Africa. Full article

Pentadesma butyracea is a medicinal plant of which bark decoctions are used in traditional medicine for the treatment of diarrhea symptoms in Gabon. The aim of the present work was to perform phytochemical and pharmacological analyses of decoctions of P. butyracea bark. In a principal approach, spectrophotometric analyses were used to quantify phenolic compounds, followed by liquid chromatography coupled to mass spectrometry analysis that allowed the identification of flavanone–flavone dimers as the main metabolites. Pharmacological analyses showed the absence of toxicity, thus confirming the safety of use of this decoction in traditional medicine. The antioxidant activity of the bark decoctions was demonstrated to depend on their phenolic contents. The decoction of stem barks harvested during the rainy season also induced a dose-dependent relaxation of isolated ileum fragments from Wistar rats. In addition, the antidiarrheal activity of P. butyracea barks was investigated against castor oil-induced diarrhea. The oral administration of different concentrations of this decoction led to a decrease in wet stools, indicating an antidiarrheal effect at the doses that were used. These results encourage the deepening of bio-guided research on P. butyracea bark decoctions in order to propose standard traditional medical treatments. Full article