Ahmed Zaid - Academia.edu (original) (raw)

Papers by Ahmed Zaid

Zenodo (CERN European Organization for Nuclear Research), Mar 31, 2022

Frontiers in Psychiatry

Background: The COVID-19 pandemic has led to an increase in the risk of suicide, uncertainty, men... more Background: The COVID-19 pandemic has led to an increase in the risk of suicide, uncertainty, mental stress, terror, annoyance, weariness, financial issues, and frustration. We aim to determine the prevalence of insomnia, depressive and anxiety symptoms, and their associated factors among Libyan populations during the COVID-19 pandemic and the civil war.Methods: An online cross-sectional survey was conducted among the Libyan population between July 18 and August 23, 2020. The data collected included basic demographic characteristics, level of education, employment status, COVID-19-related questions, and questions about abuse and domestic violence. This study assessed the psychological status of participants who were screened for anxiety symptoms using the seven-item Generalized Anxiety Disorder scale (GAD-7). Depressive symptoms were also screened for using the two-item Patient Health Questionnaire (PHQ-2) and the Insomnia Severity Index (ISI). Binomial logistic regression was used ...

PLOS ONE

Background The coronavirus disease 2019 (COVID-19) pandemic may have a potentially serious effect... more Background The coronavirus disease 2019 (COVID-19) pandemic may have a potentially serious effect on mental health and increase the risk of anxiety, depression, and post-traumatic stress disorders in people. In this study, we aimed to determine the prevalence of psychological illness and the impact of the COVID-19 pandemic on the Libyan population’s mental health. Method A cross-sectional survey, conducted in both online and paper modes and consisting of five sections, was completed in more than 30 cities and towns across Libya. The first section consisted of questions on basic demographic characteristics. The second section contained a survey related to the lockdown status, activities, related stress levels, and quarantine. The third section comprised the self-administered 9-item Patient Health Questionnaire (PHQ-9). The fourth section contained the 7-item Generalized Anxiety Disorder Scale (GAD-7), and the fifth section contained the Impact of Event Scale-Revised (IES-R). Result O...

The GC-box is an important transcriptional regulatory element present in the promoters of many ma... more The GC-box is an important transcriptional regulatory element present in the promoters of many mammalian genes, and is found in most, if not all, oxidative phosphorylation (OXPHOS) promoters. In the present study we examine the effects of three Sp1 family members (Sp2, Sp3, and Sp4) on the adenine nucleotide translocase 2, cytochrome c1, F1-ATPase β-subunit, and the mitochondria transcription factor (mtTFA) promoters in Drosophila SL2 cell line. Sp3, like Sp1, strongly activates transcription all four promoters. SP4 stimulates, moderately, but Sp2 had no effect. In addition, Sp3 can, like Sp1, inhibit transcription from the proximal promoter of the ANT2 gene through binding to the Cbox GC element. By contrast, Sp4 and Sp2 do not repress promoter activity. Furthermore, since Sp4 and Sp2 bind to the Cbox repression element on the ANT2 promoter, but do not repress transcription, inhibition of transcription cannot be explained by steric hindrance of pre-initiation complex assembly. Thes...

Background: PCSK9 is primarily expressed in liver and intestine and was recently identified as th... more Background: PCSK9 is primarily expressed in liver and intestine and was recently identified as the third locus implicated in autosomal dominant hypercholesterolemia, after LDLR and APOB. PCSK9 transits through the secretory pathway, associates with LDLR and triggers its degradation in endodomal/lysosomal compartments. Hypothesis: Mice lacking PCSK9 specifically in liver or intestine will define the tissue-specific contribution of PCSK9 to cholesterol homeostasis, and whether the latter is exclusively dependent on LDLR. Methods: Conditional Pcsk9 knockout mice in which the proximal promoter and exon 1 were framed with loxP sites were obtained. Using Cre-expressing mice, we generated complete (Pcsk9−/ −), hepatocyte ( Alb-cre )- or enterocyte ( Vil-cre )-specific knockouts. We also generated double knockout mice lacking both LDLR and PCSK9 and transgenic mice overexpressing mouse V5-tagged PCSK9 in hepatocytes. Results: PCSK9-deficient mice were hypocholesterolemic (−42% in plasma cho...

PLOS ONE, 2021

BackgroundThe coronavirus disease (COVID-19) pandemic has severely affected African countries, sp... more BackgroundThe coronavirus disease (COVID-19) pandemic has severely affected African countries, specifically the countries, such as Libya, that are in constant conflict. Clinical and laboratory information, including mortality and associated risk factors in relation to hospital settings and available resources, about critically ill patients with COVID-19 in Africa is not available. This study aimed to determine the mortality and morbidity of COVID-19 patients in intensive care units (ICU) following 60 days after ICU admission, and explore the factors that influence in‐ICU mortality rate.MethodsThis is a multicenter prospective observational study among COVID-19 critical care patients in 11 ICUs in Libya from May 29th to December 30th 2020. Basic demographic data, clinical characteristics, laboratory values, admission Sequential Organ Failure Assessment (SOFA) score, quick SOFA, and clinical management were analyzed.ResultWe included 465 consecutive COVID-19 critically ill patients. T...

Frontiers in Psychiatry, 2020

Objective: We aimed to determine the prevalence of burnout among hospital healthcare workers in L... more Objective: We aimed to determine the prevalence of burnout among hospital healthcare workers in Libya during the coronavirus disease (COVID-19) pandemic and civil war.Methods: A cross-sectional study was conducted from April 18 to May 2, 2020 among Libyan healthcare workers. Data on participant characteristics were collected with a specifically designed questionnaire. Burnout was assessed with the abbreviated Maslach Burnout Inventory (aMBI) comprising three subscales: emotional exhaustion (EE), depersonalization (DP), and personal accomplishment (PA), with each sub-scale score range from 0 to 18. For EE and DP, scores of 10 to 18 were regarded as “moderate to severe burnout.” PA was scored inversely, where a score ≤ 10 indicated severe burnout.Results: The study yielded a sample size of 532 participants. Of these, 357 (67.1%) reported emotional exhaustion (EE Score ≥ 10), 252 (47.4%) reported depersonalization (DP score ≥ 10), and 121 (22.7%) reported a lower sense of personal acco...

BMC Public Health, 2021

Background This study determined the knowledge, attitudes, and practice regarding COVID-19 and as... more Background This study determined the knowledge, attitudes, and practice regarding COVID-19 and assessed the acceptance of the COVID-19 vaccine among healthcare workers and the general population. Methods A web-based, cross-sectional study was conducted using convenience sampling in Libya from December 1 to 18, 2020 among the general population and healthcare workers. Data on demographic characteristics, COVID-19 vaccination-related concerns, knowledge, attitudes, and practice regarding COVID-19, and knowledge, attitudes, and acceptance regarding the COVID-19 vaccine were collected using a self-administered survey. A binomial logistic regression was performed with 70% efficacy to determine the association between acceptance of the vaccine and study variables. Results Valid and complete responses were collected from 15,087 participants. Of these, 6227 (41.3%) were male and 8860 (58.7%) were female, with a mean (SD) age of 30.6 ± 9.8 years. Moreover, 485 (3.2%) participants were infect...

The American Journal of Tropical Medicine and Hygiene, 2020

Circulation, Oct 31, 2007

Proceedings of the National Academy of Sciences, 2008

The proprotein convertase PC5/6 cleaves protein precursors after basic amino acids and is essenti... more The proprotein convertase PC5/6 cleaves protein precursors after basic amino acids and is essential for implantation in CD1/129/Sv/C57BL/6 mixed-background mice. Conditional inactivation of Pcsk5 in the epiblast but not in the extraembryonic tissue bypassed early embryonic lethality but resulted in death at birth. PC5/6-deficient embryos exhibited Gdf11-related phenotypes such as altered anteroposterior patterning with extra vertebrae and lack of tail and kidney agenesis. They also exhibited Gdf11-independent phenotypes, such as a smaller size, multiple hemorrhages, collapsed alveoli, and retarded ossification. In situ hybridization revealed overlapping PC5/6 and Gdf11 mRNA expression patterns. In vitro and ex vivo analyses showed that the selectivity of PC5/6 for Gdf11 essentially resides in the presence of a P1′ Asn in the RSRR↓N cleavage motif. This work identifies Gdf11 as a likely in vivo specific substrate of PC5/6 and opens the way to the identification of other key substrate...

Oncogene, 2000

The p53 tumor suppressor protein inhibits the formation of tumors through induction of cell cycle... more The p53 tumor suppressor protein inhibits the formation of tumors through induction of cell cycle arrest and/or apoptosis. In the present study we demonstrated that p53 is also a powerful inhibitor of human telomerase reverse transcriptase (hTERT), a key component for telomerase. Activation of either exogenous temperature-sensitive (ts) p53 in BL41 Burkitt lymphoma cells or endogenous wild type (wt) p53 at a physiological level in MCF-7 breast carcinoma cells triggered a rapid downregulation of hTERT mRNA expression, independently of the induction of the p53 target gene p21. Co-transfection of an hTERT promoter construct with wt p53 but not mutant p53 in HeLa cells inhibited the hTERT promoter activity. Furthermore, the activation of the hTERT promoter in Drosophila Schneider SL2 cells was completely dependent on the ectopic expression of Sp1 and was abrogated by wt p53. Finally, wt p53 inhibited Sp1 binding to the hTERT proximal promoter by forming a p53-Sp1 complex. Since activation of telomerase, widely observed in human tumor cell lines and primary tumors, is a critical step in tumorigenesis, wt p53-triggered inhibition of hTERT/telomerase expression may re¯ect yet another mechanism of p53mediated tumor suppression. Our ®ndings provide new insights into both the biological function of p53 and the regulation of hTERT/telomerase expression. Oncogene (2000) 19, 5123 ± 5133.

Journal of Biochemistry, 1999

Abstract The mammalian ATP/ADP translocator isoform-2 (ANT2) gene is growth-activated. Regulation... more Abstract The mammalian ATP/ADP translocator isoform-2 (ANT2) gene is growth-activated. Regulation of the gene appears to involve Spl, as an essential activator, and a suppressor through an Spl core element next to the transcription start. We show here that the proximal ...

Circulation, 2012

Background— The proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes independently of i... more Background— The proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes independently of its enzymatic activity the degradation of the low-density lipoprotein (LDL) receptor. PCSK9 gain of function in humans leads to autosomal dominant hypercholesterolemia, whereas the absence of functional PCSK9 results in ≈7-fold lower levels of LDL cholesterol. This suggests that lowering PCSK9 may protect against atherosclerosis. Methods and Results— We investigated the role of PCSK9 in atherosclerosis in C57BL/6 wild-type (WT), apolipoprotein E–deficient, and LDL receptor–deficient mouse models. Circulating cholesterol levels, fast protein liquid chromatography profiles, aortic cholesteryl esters (CE), and plaque sizes were determined. Intima-media thicknesses were measured by ultrasound biomicroscopy. First, mice expressing null (knockout [KO]), normal (WT), or high (transgenic [Tg]) levels of PCSK9 were fed a 12-month Western diet. KO mice accumulated 4-fold less aortic CE than WT mice...

Biochemical Journal, 2000

ChemBioChem, 2004

Oligonucleotide‐directed triple‐helix formation provides a rational means to interfere with genom... more Oligonucleotide‐directed triple‐helix formation provides a rational means to interfere with genomic DNA targets and to direct modifications at specific sites. We have developed a new class of compounds that, at low concentrations, efficiently targets and damages double‐stranded DNA specifically at the site where a triple‐helical structure is formed. In these new compounds, a triple‐helix‐specific intercalator—benzoquinoquinoxaline (BQQ)—was coupled to one of two isomeric 1,10‐phenanthrolinecarboxaldehyde derivatives. 1,10‐Phenanthroline derivatives are known to cleave DNA in the presence of copper ions. The obtained BQQ‐1,10‐phenanthroline (BQQ–OP) conjugates were compared with regard to their ability to cleave triple‐helix DNA. Both conjugates displayed a sequence preference inside the triple‐helical site, as judged from the more pronounced cleavage obtained at stretches of T⋅A×T base triplets.