Publications by authors named "Gharbi D"

Background: Ragweed is an invasive, highly allergenic weed predicted to expand its habitat with warming global temperatures. Several species have been identified in South Africa for well over a century; however, its presence remained undetected by allergists and aerobiologists until the development of an extensive aerospora monitoring system across South African urban areas since 2019. This paper presents the inventory of preliminary investigation of the airborne pollen and the taxonomic identification of ragweed species.

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Article Synopsis
  • Antibiotic resistance and biofilm formation in Gram-negative bacteria pose significant challenges for infection control, particularly through the Quorum Sensing (QS) mechanism.
  • Myrtle leaf extract demonstrated a potent anti-QS effect, inhibiting 80% of violacein production and significantly reducing various virulence factors like biofilm formation and protease activity at sub-MIC concentrations.
  • The study identified three phenolic compounds from the extract, with 3,5-di-galloylquinic acid showing the strongest interaction with the CviR QS receptor, indicating potential for developing new QS inhibitors against resistant pathogens.
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This paper provides an overview of the HEAT (Healthy Environments for AthleTes) project, which aims to understand the impact of environmental conditions on athlete health and performance during major sporting events such as long-distance running, cycling, and triathlons. In collaboration with the SAFER (Strategies to reduce Adverse medical events For the ExerciseR) initiative, the HEAT project carried out a field campaign at the 2022 Comrades Marathon in the KwaZulu-Natal province of South Africa. The measurement campaign deployed seven weather stations, seven PM monitors and one spore trap along the 90 km route to capture spatially representative measurements of complex micro-climates, allergenic aerospora, and particulate matter exposure.

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  • - The study evaluated the antioxidant, antibacterial, antiviral, and anti-inflammatory properties of various parts (flowers, leaves, seeds) of a specific plant using 80% methanol extraction and microdilution techniques.
  • - Flower extracts demonstrated significant antimicrobial effectiveness against Gram-positive bacteria, as well as strong antioxidant and anti-inflammatory properties, with no toxic effects on macrophage cells.
  • - Two beneficial molecules, 12α-hydroxydaturametelin B and daturametelin B, were identified from the flower extract, showing promising potential for treating inflammatory disorders through effective binding with pro-inflammatory agents.
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Due to the numerous side effects of conventional drugs against herpetic infections and the growing phenomenon of resistance, the researchers turned to natural compounds as a source of new drugs because they are less toxic than the synthetic molecules. This study aimed to analyse the activity of male floral bud extracts, against the replication of herpes simplex virus type 2, as well as to investigate their mode of action, isolate, and identify the active compound. Cell viability and anti-herpes virus activity were performed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and the plaque reduction assay, respectively.

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Knowledge about diurnal, seasonal, and annual fluctuations in airborne pollen and fungal spores in any geographical area is essential for effective diagnosis and treatment of allergies. Aerobiological analysis enables the detection of airborne pollen and spores, thus providing information on plant phenology, plant distribution, related diseases, and the risks for some species in terms of allergies. Although pollen and fungal spores have been widely studied as aeroallergens throughout the world, not much is known about the biological aerosols in countries with a desert environment; and these could be present in much higher concentrations than expected.

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Background: The increasing number of aerobiological stations empower comparative studies to determine the relationship between pollen concentrations in different localities and the appropriate distance, which should be established between sampling stations. In Qatar, this is basically the first aerobiological study for a continuous monitoring interval.

Objectives: The study aimed to assess the abundance and seasonality of the most prevalent pollen types, plus identify potential differences between two sites within the country.

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Limited studies correlate allergic symptoms and associated outdoor biological particle exposure among schoolchildren globally.This study aimed to investigate the relationship between the seasonality of symptoms of allergic diseases among middle schoolchildren and the annual variation of airborne pollen and fungal spore in a hot and humid geographical region (Qatar).During November 2017 to January 2018, a self-reported study of middle schoolchildren living in the Doha capital city of Qatar was conducted, and data gathered were evaluated in relation to the collected monthly pollen and fungal spores.

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Background: The aim of this study was to characterize the transmission chains and clusters of COVID-19 infection in Tunisia.

Methods: All cases were confirmed by Reverse Transcriptase Polymerase Chain Reaction of a nasopharyngeal specimen. Contact tracing is undertaken for all confirmed cases in order to identify close contacts that will be systematically screened and quarantined.

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Background: The outbreak of coronavirus disease (COVID-19) continues to constitute an international public health concern. Few data are available on the duration and prognostic factors of the disease. We aimed to study the recovery time among a Tunisian cohort of COVID-19 confirmed patients and identify the prognostic factors.

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Background: Describing transmission dynamics of the outbreak and impact of intervention measures are critical to planning responses to future outbreaks and providing timely information to guide policy makers decision. We estimate serial interval (SI) and temporal reproduction number (R) of SARS-CoV-2 in Tunisia.

Methods: We collected data of investigations and contact tracing between March 1, 2020 and May 5, 2020 as well as illness onset data during the period February 29-May 5, 2020 from National Observatory of New and Emerging Diseases of Tunisia.

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Background: Pollen is a major cause of allergic respiratory diseases. In Qatar, data on the presence and prevalence of allergenic airborne types of pollen is quite limited.

Methods: The study aimed to determine and correlate the most frequently implicated airborne pollen detected by aerobiological monitoring samplers in respiratory allergy symptoms.

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Daily fluctuations of the airborne pollen concentrations produce variations on symptomatology in allergic population. Such fluctuations are influenced by local vegetal coverage, flowering phenology, geography and climatology. Since 1991, airborne pollen of Malaga province (southern Spain) has been monitored in 7 different locations.

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Article Synopsis
  • Researchers isolated a strain of Bacillus amyloliquefaciens, named C5, from olive tree roots, which produces antibacterial biosurfactant lipopeptides.
  • They optimized its antibacterial activity using grape seed flour (GSF) at different concentrations, finding 0.2% GSF yielded the best growth and antimicrobial results, with an MIC of 60 μg/ml.
  • Thin layer chromatography and MALDI-TOF/MS analyses indicated the production of multiple lipopeptides, including surfactin and bacillomycin D, highlighting GSF as an effective and affordable medium supplement for biosurfactant production.
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Towards the development of vaccines against urinary tract infections (UTI), we determined the ability of intramuscular (i.m.) immunization to result in antigen-specific antibodies in urine.

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  • * Cinnamomum verum and Pelargonium graveolens showed the best results, with significant inhibition of Candida's secreted aspartic protease (SAP) activity and a strong reduction in ergosterol levels, essential for fungal cell membranes.
  • * The findings suggest that combining these essential oils with fluconazole could enhance treatment effectiveness for Candida infections, potentially leading to better therapeutic options for patients.
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Non-muscle-invasive bladder cancer (NMIBC) is a highly recurrent tumor despite intravesical immunotherapy instillation with the bacillus Calmette-Guérin (BCG) vaccine. In a prospective longitudinal study, we took advantage of BCG instillations, which increase local immune infiltration, to characterize immune cell populations in the urine of patients with NMIBC as a surrogate for the bladder tumor microenvironment. We observed an infiltration of neutrophils, T cells, monocytic myeloid-derived suppressor cells (M-MDSCs), and group 2 innate lymphoid cells (ILC2).

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Unlabelled: Blockade of inhibitory receptors (IRs) overexpressed by T cells can activate antitumor immune responses, resulting in the most promising therapeutic approaches, particularly in bladder cancer, currently able to extend patient survival. Thanks to their ability to cross-present antigens to T cells, dendritic cells (DCs) are an immune cell population that plays a central role in the generation of effective antitumor T-cell responses. While IR function and expression have been investigated in T cells, very few data are available for DCs.

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A strain producing chitinase, isolated from potato stem tissue, was identified as Bacillus licheniformis by biochemical properties and 16S RNA sequence analysis. Statistical experimental designs were used to optimize nine independent variables for chitinase production by B. licheniformis AT6 strain in submerged fermentation.

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Purpose: Treatments with cancer vaccines may be delivered as combination therapies for better efficacy. Addition of intravesical immunostimulation with bacteria promotes vaccine-specific T cells in the bladder and tumor-regression in murine bladder cancer models. Here, we determined whether an adjuvanted cancer vaccine can be safely administered with concomitant standard intravesical Bacillus-Calmette-Guérin (BCG) therapy and how vaccine-specific immune responses may be modulated in patients with non-muscle-invasive bladder cancer (NMIBC).

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Among nine chitinase-producing strains isolated from Tunisian soil, one isolate called S213 exhibited a potent chitinolytic activity. S213 strain was identified as Bacillus licheniformis by API 50CH system and sequence analysis of its partial 16S ribosomal DNA. Chitinolytic activity was induced either by colloidal chitin or fungal cell walls, and the highest chitinase activity reached at the late stationary phase exhibiting optimal temperature and pH of 50-60 °C and pH 6.

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In the present study, we evaluated the antioxidant and the scavenging ability of C14, C15 and C16 bacillomycin D-like lipopeptides produced by B38 strain. They all displayed strong reducing power activity, hydroxyl and superoxide anion radicals scavenging activities and inhibition of lipid peroxidation. In addition, they were found to protect plasmid DNA damage from hydroxyl radical oxidation.

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The control of arterial hypertension (HT) is an endlessly hoped objective but usually not reached. Several factors are determinants. The physician role is crucial in the HT prevention.

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The study objective was to assess the prevalence, level of awareness of treatment, and control of hypertension in a general population. We conducted a cross-sectional survey on 1837 adults 40-69 years old. Hypertension and control level are defined according to the WHO/ISH recommendations.

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