Publications by authors named "Andrea M Stringer"

Vitamin D has been proposed to attenuate chemotherapy-induced gastrointestinal mucositis (GM). In the intestine, local catabolism of active vitamin D [1,25-dihydroxyvitamin D₃] is mediated by the enzyme Cyp24a1. This study assessed whether deletion of Cyp24a1 specifically in intestinal epithelial cells can protect against 5-fluorouracil (5-FU)-induced intestinal injury and microbiome disruption in mice.

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Background: Severe alcohol-associated hepatitis (sAH) has a high short-term mortality, with limited treatment options. Fecal microbiota transplantation (FMT) has shown benefits in small, uncontrolled studies.

Aim: Perform a systematic review and meta-analysis to provide updated evidence on the efficacy and safety of FMT in sAH patients.

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Advances in the treatment of cancer have significantly improved mortality rates; however, this has come at a cost, with many treatments still limited by their toxic side effects. Mucositis in both the mouth and gastrointestinal tract is common following many anti-cancer agents, manifesting as ulcerative lesions and associated symptoms throughout the alimentary tract. The pathogenesis of mucositis was first defined in 2004 by Sonis, and almost 20 years on, the model continues to be updated reflecting ongoing research initiatives and more sophisticated analytical techniques.

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Introduction: The trillions of microorganisms that comprise the gut microbiome form dynamic bidirectional interactions with orally administered drugs and host health. These relationships can alter all aspects of drug pharmacokinetics and pharmacodynamics (PK/PD); thus, there is a desire to control these interactions to maximize therapeutic efficacy. Attempts to modulate drug-gut microbiome interactions have spurred advancements within the field of 'pharmacomicrobiomics' and are poised to become the next frontier of oral drug delivery.

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Purpose Of The Review: Gastrointestinal mucositis (GM) is a severe side effect of cancer treatments, negatively impacting the patient's quality of life, and has limited treatment. GM consists of complex biological processes involving apoptosis and inflammation, leading to damage and ulceration of the gastrointestinal system. Recently, vitamin D has been shown to have multiple roles in the gut, including immunomodulation, epithelial barrier regulation and microbiome regulation.

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Purpose Of Review: Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has resulted in a global pandemic, with people with other conditions at greater risk of severe infection with intensified symptoms across multiple organ systems. Patients with cancer are at greater risk, and it is likely that those receiving treatment will experience greater incidence and severity of gastrointestinal toxicities, such as gastrointestinal mucositis, due to SARS-CoV-2 binding to angiotensin-converting enzyme (ACE)2 in the intestine.

Recent Findings: Recent studies have shown that SARS-CoV-2 patients experience gastrointestinal toxicities, and SARS-CoV-2 has capacity to infect intestinal cells through binding to ACE2 expressed in the intestine.

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Article Synopsis
  • Vitamin D regulation in humans primarily relies on the enzyme CYP24A1, which hydroxylates key vitamin D metabolites, and its upregulation is linked to diseases like chronic kidney disease (CKD).
  • Increased CYP24A1 activity in CKD leads to reduced vitamin D effectiveness, contributing to issues like secondary hyperparathyroidism and bone loss.
  • Researchers developed a new vitamin D analogue that inhibits CYP24A1, showing promise in enhancing vitamin D activity and potentially offering a new treatment approach for secondary hyperparathyroidism.
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Objectives: To circumvent cisplatin (CDDP) toxic effects and improve the antitumoural effect, our research group developed long-circulating and pH-sensitive liposomes containing CDDP (SpHL-CDDP). This study aimed to evaluate whether SpHL-CDDP is associated with intestinal protection under in-vitro conditions in the presence of host-microbiota, compared with free CDDP.

Methods: The cytotoxicity of CDDP and SpHL-CDDP were evaluated by colorimetric MTT and sulforhodamine B (SRB) assays.

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Purpose Of Review: An overwhelming majority of chemotherapy agents are known to cause gastrointestinal mucositis, an unwanted side effect of cancer treatment, for which no effective treatment currently exists. The pathological processes underlying the development of gastrointestinal mucositis are many and varied, with multiple pathways thought to be involved in initiation of inflammation and apoptosis. Physiological and or biochemical-based deficiencies, such as vitamin D deficiency and gut microbiome density and population, are also thought to have an impact on mucositis severity.

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Purpose: To update the clinical practice guidelines for the use of growth factors and cytokines for the prevention and/or treatment of oral mucositis (OM).

Methods: A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). The body of evidence for each intervention, in each cancer treatment setting, was assigned an evidence level.

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Unlabelled: Vitamin D activity is associated with the modulation of a wide variety of biological systems, in addition to its roles in calcium homeostatic mechanisms. While vitamin D is well known to promote gastrointestinal calcium absorption, vitamin D also plays a role in attenuating and/or preventing the progression of several gastrointestinal diseases including Crohn’s disease, ulcerative colitis, and colorectal cancer, and may also play a role in chemotherapy-induced intestinal mucositis. The pro-differentiation, immunomodulatory, and anti-inflammatory effects of vitamin D, which has been reported in numerous circumstances, are key potential mechanisms of action in the prevention of gastrointestinal disorders.

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Article Synopsis
  • This study aimed to update clinical guidelines for preventing and treating gastrointestinal mucositis (GIM) in cancer patients.
  • The Mucositis Study Group conducted a systematic review of 78 papers, ultimately including 25 in their final assessment, but found no new guidelines due to inadequate evidence.
  • The existing recommendations for probiotics and hyperbaric oxygen therapy remain unchanged, and further research is needed for other potential treatments like palifermin and glutamine.
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Purpose Of Review: Mucositis remains a prevalent, yet poorly managed side effect of anticancer therapies. Mucositis affecting both the oral cavity and gastrointestinal tract predispose to infection and require extensive supportive management, contributing to the growing economic burden associated with cancer care. Animal models remain a critical aspect of mucositis research, providing novel insights into its pathogenesis and revealing therapeutic targets.

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Purpose: Radiotherapy-induced gut toxicity (RIGT) is a debilitating effect of radiotherapy for cancer, often resulting in significant diarrhea and pain. Previous studies have highlighted roles of the intestinal microvasculature and matrix metalloproteinases (MMPs) in the development of RIGT. We hypothesized vascular mediators would be significantly altered in a dark agouti (DA) rat model of RIGT.

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Purpose: Radiotherapy-induced gut toxicity (RIGT) is associated with significant diarrhoea, pain and rectal bleeding. Matrix metalloproteinases (MMPs) have been reported to be involved in chemotherapy-induced gut toxicity and RIGT following single-dose irradiation in vivo. We therefore proposed MMPs would be involved in the pathobiology of RIGT following fractionated irradiation.

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Mucositis is a side effect associated with the use of chemotherapy, and has a significant impact on the quality of life. Mucositis, by definition, refers to the inflammation of the mucosa and occurs throughout the alimentary tract from the mouth to anus. Nuclear Factor kappa B (NFκB) encompasses a family of transcription factors, which upregulate pro-inflammatory cytokines.

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Article Synopsis
  • The study investigates radiotherapy-induced gut toxicity (RIGT), characterized by symptoms like diarrhea and rectal bleeding, focusing on alterations in the microvasculature of the gastrointestinal tract after radiation exposure.
  • Female Dark Agouti rats were subjected to a specific 6-week radiation treatment, with assessments conducted at 3, 6, and 15 weeks for signs of injury, including cell death and structural changes.
  • Results showed significant apoptosis of microvascular cells in the jejunum and colon at later time points, along with histopathological changes like thickened blood vessels, indicating that the intestinal microvasculature undergoes both acute and chronic alterations due to fractionated radiotherapy.
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Purpose: A common side effect of irinotecan administration is gastrointestinal mucositis, often manifesting as severe diarrhoea. The damage to the structure and function of the gastrointestinal tract caused by this cytotoxic agent is debilitating and often leads to alterations in patients' regimens, hospitalisation or stoppage of treatment. The purpose of this review is to identify mechanisms of irinotecan-induced intestinal damage and a potential role for GLP-2 analogues for intervention.

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Objectives: Matrix metalloproteinases (MMPs) are involved in both maintenance of healthy mucosa and mediation of several pathologies. Recently, MMPs and their inhibitors have attracted attention as potential mediators of mucositis. We investigated tissue expression of MMP-3 and MMP-9 over time in a pre-clinical model of irinotecan-induced oral mucositis (OM).

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Introduction: Diarrhoea caused by treatment with receptor tyrosine kinase inhibitors (TKI) targeting Epidermal Growth Factor Receptors (EGFR) is an important clinical toxicity in oncology that remains poorly understood. This study aimed to identify histological and molecular changes within the intestine following lapatinib to elucidate mechanisms of diarrhoea related to treatment with this dual EGFR TKI.

Methods And Materials: Male albino Wistar rats were orally gavaged lapatinib at 100, 240 or 500 mg/kg daily for 4 weeks and assessed for indicators of gastrointestinal injury at the end of each week.

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Chemotherapy-induced mucositis is considered to be a major oncological problem, caused by the cytotoxic effects of cancer chemotherapy. In the last 10 years, there have been significant advances in the understanding of mucositis pathobiology. At the basic level, it is now well-understood that it is not just an epithelial process, but rather a complex interaction between epithelial and connective tissue compartments.

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Background: Considerable progress has been made in our understanding of the biological basis for cancer therapy-induced mucosal barrier injury (mucositis). The last formal review of the subject by MASCC/ISOO was published in 2007; consequently, an update is timely.

Methods: Panel members reviewed the biomedical literature on mucositis pathobiology published between January 2005 and December 2011.

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