Publications by authors named "Omaima Sabek"

Human pluripotent stem cell-derived β-cells (SC-β-cells) represent an alternative cell source for transplantation in diabetic patients. Although mitogens could in theory be used to expand β-cells, adult β-cells very rarely replicate. In contrast, newly formed β-cells, including SC-β-cells, display higher proliferative capacity and distinct transcriptional and functional profiles.

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This study was to determine whether extracellular vesicles (EVs) derived from insulin-producing cells (IPCs) can modulate naïve mesenchymal stromal cells (MSCs) to become insulin-secreting. MSCs were isolated from human adipose tissue. The cells were then differentiated to generate IPCs by achemical-based induction protocol.

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Purpose: In the aftermath of a nuclear disaster or accident, survivors will suffer from radiation-induced normal tissue damage. Recovery after radiation exposure is dictated by several factors, one of which is degree of shielding at time of exposure. This study aims to characterize the short and late term changes in kinetics and magnitude of pancytopenia and blood chemistry in a model of heterogeneous radiation exposure, or partial body irradiation (PBI), compared to whole body irradiation (WBI).

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Metabolic syndrome (MetS) is an increasing global health threat and strong risk factor for type 2 diabetes (T2D). MetS causes both hyperinsulinemia and islet size overexpansion, and pancreatic β-cell failure impacts insulin and proinsulin secretion, mitochondrial density, and cellular identity loss. The low-density lipoprotein receptor knockout (LDLr-/-) model combined with high-fat diet (HFD) has been used to study alterations in multiple organs, but little is known about the changes to β-cell identity resulting from MetS.

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Unlabelled: Islet and β-cell function is intrinsic to glucose homeostasis. Pancreatectomy and islet autotransplantation (PIAT) for chronic pancreatitis (CP) treatment is a useful model for assessing islet function in the absence of immune-suppression and to perform extensive presurgical metabolic evaluations not possible from deceased donors. We recently showed that in CP-PIAT patients, preoperative islet identity loss presented with postoperative glycemic loss.

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In vitro derivation of pancreatic β-cells from human pluripotent stem cells holds promise as diabetes treatment. Despite recent progress, efforts to generate physiologically competent β-cells are still hindered by incomplete understanding of the microenvironment's role in β-cell development and maturation. Here, we analyze the human mesenchymal and endothelial primary cells from weeks 9-20 fetal pancreas and identify a time point-specific microenvironment that permits β-cell differentiation.

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Purpose: Compared with photon cranial radiation therapy (X-CRT), proton cranial radiation therapy (P-CRT) offers potential advantages in limiting radiation-induced sequalae in the treatment of pediatric brain tumors. This study aims to identify cognitive, functional magnetic resonance and positron emission tomography imaging markers and molecular differences between the radiation modalities.

Methods And Materials: Juvenile rats received a single faction of 10 Gy (relative biological effectiveness-weighted dose) delivered with 6 MV X-CRT or at the midspread out Bragg peak of a 100 MeV P-CRT beam.

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Mesenchymal stem cell (MSC)-based therapy for type 1 diabetes mellitus (T1DM) has been the subject matter of many studies over the past few decades. The wide availability, negligible teratogenic risks and differentiation potential of MSCs promise a therapeutic alternative to traditional exogenous insulin injections or pancreatic transplantation. However, conflicting arguments have been reported regarding the immunological profile of MSCs.

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Purpose: Cranial radiation therapy (CRT) is a common treatment for pediatric brain tumor patients. However, side effects include significant neurobehavioral dysfunction in survivors. This dysfunction may in part be caused by inflammation, including increased production of tumor necrosis factor alpha (TNFα) and its receptor TNFR1, which can activate the nuclear factor kappa light-chain enhancer of activated B cells (NF-κB).

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Both hard material photolithography and soft lithography are widely used for patterned cell culture. Soft lithography techniques enable bioactive molecule incorporation, however complex surface modifications are required to introduce specific ligands or proteins in conventional photolithography. In this study, we demonstrate human umbilical vein cell (HUVEC) and adult bone marrow derived mesenchymal stem cell (MSC) patterning on titanium diboride (TiB) layers deposited on silicon (Si) substrates by electron-beam evaporation and micropatterned using photolithography.

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Background: We explored the association of C-peptide (marker of secreted insulin), proinsulin and proinsulin ⁄C-peptide ratio (PI/C) (markers of beta-cell endoplasmic reticulum [ER] stress) with undercarboxylated (uOC) and carboxylated osteocalcin (cOC) and their ratio (uOC/cOC) in children with recently diagnosed type 1 (T1D) or type 2 diabetes (T2D), and the correlation of these variables with partial remission (PR) in children with T1D.

Methods: Demographic and clinical data of children with new-onset diabetes (n = 68; median age = 12.2 years; 33.

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In the aftermath of a nuclear incident, survivors will suffer the deleterious effects from acute radiation exposure. The majority of those affected would have received heterogeneous radiation exposure, reflected in hematological metrics and blood chemistry. Here, we investigated the acute and long-term changes in kinetics and magnitude of pancytopenia and blood chemistry in rats irradiated using varying degrees of body shielding.

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Article Synopsis
  • Cranial radiotherapy (CRT) is effective for treating brain tumors but can cause long-term cognitive problems; this study aims to find imaging and functional markers that indicate brain injury from CRT.
  • In the experiments, male rats were irradiated and then assessed at 12 months for cognitive and imaging changes using PET and MRI, revealing deficits and significant brain structure alterations post-treatment.
  • Findings showed a correlation between cognitive decline and changes in brain imaging features such as myelin integrity and neural network organization, suggesting that these markers may help evaluate the long-term impacts of CRT and inform future treatments.
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Objectives: The objective of this study was to assess vitamin D status of US non-pregnant adults using a standardised assay across 15 mL/min/1.73 m increments of kidney function, report the use of dietary supplements containing vitamin D and assess relationships between vitamin D and markers of bone resorption.

Design: This study is a cross-sectional evaluation.

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Article Synopsis
  • Acute radiation syndrome (ARS) severity increases with the extent of body exposure, influencing survival chances and health complications.
  • The study proposes echocardiography to monitor cardiac and pulmonary function changes in irradiated animals, using rats exposed to lethal doses of radiation as a model.
  • Significant differences in cardiac function and blood characteristics were observed between whole body irradiated rats and those with only partial exposure, suggesting heart failure may be a cause of death, highlighting the need for treatments to mitigate cardiac-related mortality from radiation exposure.
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Beta-cell dedifferentiation as shown by cellular colocalization of insulin with glucagon and/or vimentin, and decreased expression of MAFA and/or urocortin3 has been suggested to contribute to metabolic decompensation in type 2 diabetes, and was recently described postimplantation in islet allotransplant patients. Dysglycaemia and diabetes mellitus are often encountered preoperatively in patients undergoing pancreatectomy and islet autotransplantation (PIAT). In this series of case reports, we document variation in islet phenotypic identity in three patients with chronic pancreatitis (CP) without diabetes or significant insulin resistance who subsequently underwent PIAT.

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Background: While cranial radiation therapy (CRT) is an effective treatment, healthy areas surrounding irradiation sites are negatively affected. Frontal lobe functions involving attention, processing speed, and inhibition control are impaired. These deficits appear months to years after CRT and impair quality of life.

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Purpose: Radiation therapy (RT) causes functional and transcriptomic changes in the brain; however, most studies have been carried out in normal rodent brains. Here, the long-term effect of irradiation and tumor presence during radiation was investigated.

Methods And Materials: Male Wistar rats ∼7 weeks old were divided into 3 groups: sham implant, RT+sham implant, and RT+tumor implant (C6 glioma).

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Although a large proportion of patients with type 2 diabetes (T2D) accumulate misfolded aggregates composed of the islet amyloid polypeptide (IAPP), its role in the disease is unknown. Here, we show that pancreatic IAPP aggregates can promote the misfolding and aggregation of endogenous IAPP in islet cultures obtained from transgenic mouse or healthy human pancreas. Islet homogenates immunodepleted with anti-IAPP-specific antibodies were not able to induce IAPP aggregation.

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Transplantation of pancreatic islets or stem cell derived insulin secreting cells is an attractive treatment strategy for diabetes. However, islet transplantation is associated with several challenges including function-loss associated with dispersion and limited vascularization as well as the need for continuous immunosuppression. To overcome these limitations, here we present a novel 3D printed and functionalized encapsulation system for subcutaneous engraftment of islets or islet like cells.

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The abscopal effect is the response to radiation at sites that are distant from the irradiated site of an organism, and it is thought to play a role in bone marrow (BM) recovery by initiating responses in the unirradiated bone marrow. Understanding the mechanism of this effect has applications in treating BM failure (BMF) and BM transplantation (BMT), and improving survival of nuclear disaster victims. Here, we investigated the use of multimodality imaging as a translational tool to longitudinally assess bone marrow recovery.

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Article Synopsis
  • Osteocalcin (OC), a hormone from bone cells, is linked to better beta-cell function and is being studied for its relationship with hemoglobin A1c (HbA1c) levels in children with diabetes.
  • A study of 70 children newly diagnosed with diabetes found that those with lower HbA1c levels had higher levels of undercarboxylated OC (uOC), especially among those with type 2 diabetes and male patients.
  • The results indicate that there is an inverse correlation between uOC levels and HbA1c, suggesting that uOC might be an important factor to explore further for managing glucose metabolism in pediatric diabetes.
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  • Positron emission tomography (PET) using 18F-FDG effectively detects inflammation in patients and was used to study gastrointestinal recovery after radiation exposure in rats.
  • The study found significant increases in inflammation and 18F-FDG uptake in the gastrointestinal tract of rats exposed to 7.5 Gy radiation, with variations observed depending on the type of irradiation (sham, upper half body shielded, whole body).
  • Interestingly, while the gastrointestinal activity returned to normal levels by day 35 post-exposure, an increase in bone marrow metabolism was observed, suggesting a connection between GI recovery and bone marrow activity following radiation exposure.
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Diabetes is one of the most prevalent, costly, and debilitating diseases in the world. Pancreas and islet transplants have shown success in re-establishing glucose control and reversing diabetic complications. However, both are limited by donor availability, need for continuous immunosuppression, loss of transplanted tissue due to dispersion, and lack of vascularization.

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Article Synopsis
  • A study was conducted using multimodal imaging techniques (PET/CT and MRI) to assess the effects of ionizing radiation on bone marrow (BM) and to map exposure location, which are crucial for understanding survival and recovery.
  • The research involved irradiating animals with different shielding methods and repeatedly imaging to quantify cellular proliferation and vascular damage in the BM post-exposure.
  • Results showed that shielding influenced recovery rates of proliferating cells in the BM, and MRI effectively detected vascular damage from radiation, corroborated by other counting methods and histopathology.
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