Exploring the role of Apolipoprotein E in normal and malignant Haematopoiesis

Apolipoprotein E (ApoE) is a gene known for its role in lipid metabolism and has an anti-atherogenic role. Consequently, the deficiency of ApoE in mice results in the development of atherosclerosis and, conversely, re-expression of the gene reduces the development of the disease. Atherosclerosis is known to involve haematopoietic cell subsets and deregulated haematopoiesis drives both clonal haematopoiesis (a pre-leukaemia syndrome) and atherosclerosis. In this thesis, I investigated the broad requirement of ApoE signalling in normal haematopoiesis and the role of ApoE signalling in haematopoiesis and the development of leukaemia in the context of a high fat diet (HFD) that drives atherosclerosis. ApoE-/- mice fed a normal chow diet (NCD) displayed normal abundance of most haematopoietic stem/progenitor (HSPC) subsets and lineage specific myeloid and lymphoid progenitors, with the exception of a marginal reduction in B cells in the bone marrow and spleen, and a decrease in Mac-1+ cells and platelets in the peripheral blood. Functionally, as assessed by colony forming cell (CFC) assays, haematopoietic progenitor formation from ApoE-/- mice was unperturbed. When ApoE-/- mice were fed an HFD, a select expansion of immunophenotypic HSPCs was observed, including expansion of the LSK compartment reflecting ApoE mediated increases in haematopoietic stem cells (HSCs), multipotent progenitors (MPPs) and committed myeloid progenitors. ApoE-/- mice fed an HFD have a HPSC late survival advantage. Unexpectedly, ApoE signalling in the context an HFD appeared, with some exceptions, to be largely unneeded for HSC functioning, as assessed by transplantation, and for HSC self-renewal, judged by secondary transplantation. To test the impact of an HFD on ApoE signalling in leukaemia, an MLL-AF9 driven model of acute myeloid leukaemia (AML) was employed. MLL-AF9 transformed HSPCs from ApoE-/- mice fed an HFD showed no differences in pre-LSC formation in vitro and when pre-LSCs were transplanted allowing the development of AML in vivo, no impact was seen on the development of leukaemia, indicating that HFD has no influence on ApoE signalling in the initiation and development of leukaemia. In conclusion, these data suggest an association between the requirement for ApoE and the regulation of steady state haematopoiesis in select mature blood cell lineages, which requires further investigation in functional in vivo experiments. ApoE signalling in HFD expands select HSPC subsets, but functionally these cells behave normally. Further experimentation will be needed to resolve the ApoE mediated transcriptional signature underlying the immunophenotypic changes in HSPCs observed in an HFD. However, ApoE signalling in HFD has no impact on leukaemogenesis in an MLL-AF9 driven model of acute myeloid leukaemia

Gata2 haploinsufficiency promotes proliferation and functional decline of HSCs with myeloid bias during aging

During aging, hematopoietic stem cell (HSC) function wanes with important biological and clinical implications for benign and malignant hematology, and other co-morbidities, such as cardiovascular disease. However, the molecular mechanisms regulating HSC aging remain incompletely defined. GATA2 haploinsufficiency driven clinical syndromes initially result in primary immunodeficiencies and routinely evolve into hematologic malignancies on acquisition of further epigenetic mutations in both young and older patients. Using a conditional mouse model of Gata2 haploinsufficiency, we discover that during aging Gata2 promotes HSC proliferation, monocytosis, and loss of the common lymphoid progenitor. Aging of Gata2 haploinsufficient mice also offsets enhanced HSC apoptosis and decreased granulocyte-macrophage progenitor number normally observed in young Gata2 haploinsufficient mice. Transplantation of elderly Gata2 haploinsufficient HSCs impairs HSC function with evidence of myeloid bias. Our data demonstrate that Gata2 regulates HSC aging and suggest the mechanisms by which Gata2 mediated HSC aging has an impact on the evolution of malignancies in GATA2 haploinsufficiency syndromes

Zeb1 modulates hematopoietic stem cell fates required for suppressing acute myeloid leukemia

Zeb1, a zinc finger E-box binding homeobox epithelial-mesenchymal (EMT) transcription factor, confers properties of ‘stemness’, such as self-renewal, in cancer. Yet little is known about the function of Zeb1 in adult stem cells. Here, we used the hematopoietic system, as a well-established paradigm of stem cell biology, to evaluate Zeb1 mediated regulation of adult stem cells. We employed a conditional genetic approach using the Mx1-Cre system to specifically knockout (KO) Zeb1 in adult hematopoietic stem cells (HSCs) and their downstream progeny. Acute genetic deletion of Zeb1 led to rapid onset thymic atrophy and apoptosis driven loss of thymocytes and T cells. A profound cell-autonomous self-renewal defect and multi-lineage differentiation block was observed in Zeb1 KO HSCs. Loss of Zeb1 in HSCs activated transcriptional programs of deregulated HSC maintenance and multi-lineage differentiation genes, and of cell polarity, consisting of cytoskeleton, lipid metabolism/lipid membrane and cell adhesion related genes. Notably, Epithelial cell adhesion molecule (EpCAM) expression was prodigiously upregulated in Zeb1 KO HSCs, which correlated with enhanced cell survival, diminished mitochondrial metabolism, ribosome biogenesis, and differentiation capacity and an activated transcriptomic signature associated with acute myeloid leukemia (AML) signaling. ZEB1 expression was downregulated in AML patients and Zeb1 KO in the malignant counterparts of HSCs - leukemic stem cells (LSCs) - accelerated MLL-AF9 and Meis1a/Hoxa9-driven AML progression, implicating Zeb1 as a tumor suppressor in AML LSCs. Thus, Zeb1 acts as a transcriptional regulator in hematopoiesis, critically co-ordinating HSC self-renewal, apoptotic and multi-lineage differentiation fates required to suppress leukemic potential in AML

Multidisciplinary approach to the treatment of a complicated crown-root fracture

Complicated crown-root fractures are uncommon type of dental trauma but usually result in significant esthetic and functional problems to those affected. This case report demonstrates sequential endodontic, restorative, orthodontic, periodontal, and prosthodontic modalities for the conservative management of a complicated crown-root fracture of the maxillary left central incisor in a young patient. After root canal treatment and core buildup, the tooth was extruded using forced orthodontic eruption for 8 weeks and retention for 7 weeks. Zinc phosphate cement acrylic crown was used to preserve esthetics and function during the forced eruption and retention period

Assessing the impact of COVID-19 on acute leukemia patients: a comparative analysis of hematological and biochemical parameters

Abstract Background The impact of COVID-19 infection on the blood system remains to be investigated, especially with those encountering hematological malignancies. It was found that a high proportion of cancer patients are at an elevated risk of encountering COVID-19 infection. Leukemic patients are often suppressed and immunocompromised, which would impact the pathology following COVID-19 infection. Therefore, this research aims to bring valuable insight into the mechanism by which COVID-19 infection influences the hematological and biochemical parameters of patients with acute leukemia. Methods This retrospective investigation uses repeated measures to examine changes in hematological and biochemical parameters among patients with acute leukemia before and after COVID-19 infection at a major Saudi tertiary center. The investigation was conducted at the Ministry of National Guard-Health Affairs in Riyadh, Saudi Arabia, on 24 acute leukemia patients with COVID-19 between April 2020 and July 2023. The impact of COVID-19 on clinical parameters, comorbidities, and laboratory values was evaluated using data obtained from the electronic health records at four designated time intervals. The relative importance of comorbidities, testing preferences, and significant predictors of survival was ascertained. Results The majority of leukemic COVID-19-infected patients, primarily detected through PCR tests, were diagnosed with acute lymphoblastic leukemia (70.8%). The hematological and biochemical parameters exhibited stability, except for a brief increase in ALT and a sustained rise in AST. These changes were not statistically significant, and parameters remained normal at all time points. Additionally, an increase in monocyte count was shown at time point-3, as well as platelet counts at time point 2. Conclusion While this study did not detect statistically significant effects of COVID-19 on biochemical and hematological parameters in acute leukemia patients, further investigation is needed to fully understand the potential adverse reactions and modifications following COVID-19 infection

A Cone Beam Computed Tomography-Based Investigation of the Frequency and Pattern of Radix Entomolaris in the Saudi Arabian Population

Background and Objectives: An understanding of the anatomical complexity of teeth is a significant factor for a successful endodontic treatment outcome. The aim of this study was to explore the frequency and pattern of distribution of radix entomolaris (RE) in mandibular first molars (MFMs) of a Saudi Arabian subpopulation using CBCT scans. Materials and Methods: This study was conducted at dental clinics of Qassim University from February to May 2023 by evaluating CBCT scans that were previously obtained for diagnostic purposes. Scans of Saudi national patients with bilaterally present MFMs and fully formed root apices were included. Conversely, scans with one/or two missing MFMs, MFMs with incomplete root apices, full- or partial-coverage prosthesis, endodontic treatment, and associated radicular resorption were excluded from study. A total of 303 CBCT scans with 606 bilateral MFMs were analyzed by two calibrated evaluators for the presence of, and type according to Song’s typolgy of RE. The data were analyzed using SPPS-24. The descriptive variables were documented as frequencies and percentages. The chi-square test was used to determine the association between the prevalence of RE with the gender, jaw side and age group. Both inter-rater and intra-rater agreements were estimated for detecting and classifying RE using Cohen’s kappa test. Results: The sample had 63.7% males and 36.3% females. The prevalence of RE was 6.6%, with Song’s type III (57.5%) as the most common variant. Absolute agreement was noted between the raters about the presence of RE and very strong agreement was noted for the classification of the RE. Conclusions: RE is an uncommon finding among the mandibular first molars of the Saudi population without any gender and quadrant predilection. The clinicians’ knowledge of the presence and Song’s type of RE may contribute towards the enhancement of endodontic treatment outcomes

Risk Factors for Glucose 6-Phosphate Dehydrogenase and COVID-19 Disease—A Retrospective Study at a Major Saudi Tertiary Center

Glucose-6-phosphate dehydrogenase (G6PD) insufficiency is a common enzymatic defect worldwide; it affects over 400 million people and is associated with various disorders. Recent research suggests that G6PD-deficient cells are susceptible to infection by human coronaviruses, as the G6PD enzyme is involved in the metabolism of oxidative stress, which may enhance COVID-19 mortality. This retrospective study aimed to examine the effect of COVID-19 on patients with G6PD deficiency by comparing the laboratory parameters of patients with G6PD enzyme deficiency alone, COVID-19 alone, and those with both COVID-19 and G6PD enzyme deficiency treated at a major Saudi tertiary center. The results indicated significant differences in hematological and biochemical parameters between the three patient groups, indicating that COVID-19 may influence these parameters, and that they could be used to measure the severity of COVID-19 disease. Moreover, this study suggests that patients with G6PD enzyme deficiency may be at higher risk for severe COVID-19 outcomes. Although the study is limited by the lack of a random selection method for group membership, the Kruskal–Wallis H-test was used to statistical assess the data. The study’s findings can enhance the understanding of the relation between COVID-19 infected and G6PD-deficiency patients and inform clinical decision making for an improved patient outcome

Evaluating the Adverse Events Associated with Three Doses of the COVID-19 Vaccination in Adults in the Western Region of Saudi Arabia: A Cross-Sectional Study

The Kingdom of Saudi Arabia was one of the countries earliest affected by the coronavirus 2019 (COVID-19) pandemic and had taken precautions including compulsory COVID-19 vaccination. Both the ChAdOx1 nCoV-19 vaccine (Oxford AstraZeneca) and the BNT162b2 vaccine (Pfizer) were approved by the Saudi Ministry of Health, followed by mRNA-1273 (Moderna), all of which were used for population-wide vaccination. This study aimed to assess the short-term side effects following the COVID-19 vaccinations among participants who had received all three doses in the western region of Saudi Arabia. An online survey was distributed to the participants who received either BNT162b2, ChAdOx1 nCoV-19, or mRNA-1273 vaccines, and the type of side effects and their severity were evaluated. Fatigue and headache, pain at the site of the injection and muscle pain were the most common side effects in all three doses. However, the severity depending on the type of vaccination was significant only for the first and second dose, but not the third dose. In contrast, there was a higher percentage of participants who encountered severe side effects from the third dose compared to the first and second. Nevertheless, the majority of participants described all three doses’ side effects to be moderately severe. A future evaluation could be made to access the individual types of vaccination and compare between the side effects of the BNT162b2, ChAdOx1 nCoV-19, and mRNA-1273 vaccines specifically for the booster dose

Relationship between apical periodontitis and missed canals in mesio-buccal roots of maxillary molars: CBCT study

الملخص: أهداف البحث: تتضمن أهداف الدراسة: ١) تقييم مدى انتشار القنوات المفقودة في الجذور البوغية الوسطى للأسنان الطواحين العلوية المعالجة عن طريق العلاج الجذري والعلاقة بينها وبين التهاب اللثة المحيط بالجذر، ٢) دراسة العلاقة بين وجود قناة البوغية الوسطى الثانية المفقودة المندمجة أو المنفصلة ومعدل انتشار التهاب اللثة المحيط بالجذر، ٣) دراسة العلاقة بين الجودة التقنية للعلاج الجذري في قناة البوغية الوسطى الأولى ومعدل انتشار التهاب اللثة المحيط بالجذر. طرق البحث: تم الحصول على ودراسة ٨٠٠ صورة من التصوير بالأشعة المقطعية المخروطية من سجلات ٨٠٠ مريض على مدى ستة أشهر. تضمنت المعلمات الملاحظة لكل سن: أ) رقم السن، ب) وجود قناة مفقودة في الجذر البوغي الوسطي، ج) تشكيل القناة البوغية الوسطى الثانية المفقودة (مندمجة أو منفصلة)، د) قبولية العلاج الجذري من الناحية التقنية للقنوات البوغية الوسطى الأولى المعالجة، هـ) نتيجة المؤشر الشعاعي الجذري على التصوير بالأشعة المقطعية المخروطية. النتائج: تم اختيار ٢٠٣ طاحنة علوية من ١٤٨ صورة من التصوير بالأشعة المقطعية المخروطية. كانت معدلات انتشار القناة البوغية الوسطى الثانية ٨٨,٢٪ في الأسنان الطواحين العلوية الأولى و٦٢,٧٪ في الأسنان الطواحين العلوية الثانية. تم العثور على القناة البوغية الوسطى الثانية في ١٦٤ من الأسنان الطواحين العلوية المعالجة من خلال العلاج الجذري. خلال العلاج، تم تفويتها في ١٥٠ سن (٩١,٥٪) وتم علاجها في ١٤ سن (٨,٥٪). أظهرت الدراسة أن 100% من الأسنان التي تم تفويتها في العلاج الجذري لها التهاب لثة محيط بالجذر، بينما ٣٥,٧٪ من الأسنان التي تم علاجها تحتوي على التهاب لثة محيط بالجذر. ظهرت الفروق في الانتشار كفروق ذات دلالة إحصائية. كانت القناة البوغية الوسطى الثانية المفقودة المندمجة أكثر انتشارا (٥٥,٢٪) من القناة البوغية الوسطى الثانية المفقودة المنفصلة (٣٣,٥٪). كان معدل انتشار التهاب اللثة المحيط بالجذر أعلى في الأسنان التي كانت تحتوي على قناة بوغية وسطى ثانية مندمجة (١٠٠٪) مقارنة بالأسنان التي كانت تحتوي على قناة بوغية وسطى ثانية منفصلة (٤٠٪). كانت الفروق في الانتشار تحمل دلالة إحصائية. الاستنتاجات: يبدو أن هناك علاقة قوية بين تفويت القناة البوغية الوسطى الثانية في أسنان الطواحين العلوية المعالجة عن طريق العلاج الجذري ووجود التهاب اللثة المحيط بالجذر. يتطلب الكشف والعلاج الصحيح للقناة البوغية الوسطى الثانية مهارة ومعرفة كبيرتين من قبل أطباء الأسنان لتجنب التهاب اللثة المحيط بالجذر. Abstract: Objectives: The objectives of this study were to: (1) assess the frequency of missed canals in the mesiobuccal root (MB) of endodontically treated maxillary molars and its association with apical periodontitis (AP); (2) examine the correlation between the presence of a confluent or separate missed MB2 canal and the prevalence of AP; and (3) examine the correlation between the technical quality of endodontic treatment in the MB1 canal and the prevalence of AP. Methods: We obtained and examined 800 cone-beam computed tomography (CBCT) scans from 800 patient records over 6 months. The parameters noted for each tooth included the tooth number; presence of missed canals in the MB root; configuration of missed MB2 canals (confluent or separate); technical acceptability of root canal treatment (RCT) of treated MB1 canals; and the CBCT periapical index score. Data were analyzed in SPSS version 24. Results: A total of 203 maxillary molars from 148 CBCT scans were included. The MB2 canal prevalence was 88.2% in maxillary first molars and 62.7% in maxillary second molars. MB2 was found in 164 endodontically treated maxillary molars. During treatment, MB2 was missed in 150 (91.5%) and treated in 14 (8.5%) teeth. A total of 103 teeth (50.73%) had AP, which was observed in 67.3% of teeth with a missed MB2 canal but only 14.3% of teeth with a treated MB2 canal. The prevalence of AP was 43.7% in teeth with confluent MB2 canals and 80.9% in teeth with separate MB2 canals. Conclusion: The MB2 canal frequency was significantly higher in the examined maxillary first molars than the maxillary second molars. The MB2 canal was missed in most teeth that underwent endodontic treatment. The AP prevalence was relatively higher in endodontically treated maxillary molars with missed MB2 canals