Ahmed Bayoumy Bayoumy

Dr. Ahmed Bayoumy Bayoumy

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Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 April 2021 in United European Gastroenterology Journal
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ABAhmed Bayoumy Bayoumy
Ahmed Bayoumy Bayoumy
CMChris J. J. Mulder
Chris J. J. Mulder
JMJaap J. Mol
Jaap J. Mol
MTMaarten E. Tushuizen
Maarten E. Tushuizen
Background: The gut fermentation syndrome (GFS), also known as the endogenous alcohol fermentation syndrome or auto brewery syndrome, is a rare and underdiagnosed medical condition where consumed carbohydrates are converted to alcohol by the microbiota in the gastrointestinal or urinary tract. The symptoms of GFS can have severe impact on patients' wellbeing and can have social and legal consequences. Unfortunately, not much is reported about GFS. The aim of this systematic review was to assess the evidence for GFS, causal micro‐organisms, diagnostics, and possible treatments.Methods: A protocol was developed prior to initiation of the systematic review (PROSPERO 207182).We performed a literature search for clinical studies on 1 September 2020 using PubMed and Embase. We included all clinical studies, including case reports that described the GFS.Results: In total, 17 case reports were included, consisting of 20 patients diagnosed with GFS. The species that caused the GFS included Klebsiella pneumoniae, Candida albicans, C. glabrata, Saccharomyces cerevisiae, C. intermedia, C. parapsilosis, and C. kefyr.Conclusions: GFS is a rare but underdiagnosed disease in daily practice. The disease is mostly reported by Saccharomyces and Candida genera, and some cases were previously treated with antibiotics. Studies in Nonalcoholic Fatty Liver disease suggest a bacterial origin of endogenous alcohol‐production, which might also be causal micro‐organisms in GFS. Current treatments for GFS include antibiotics, antifungal medication, low carbohydrate diet, and probiotics. There might be a potential role of fecal microbiota transplant in the treatment of GFS.

24 February 2020 in Expert Opinion on Drug Metabolism & Toxicology
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Journal Article
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ABAhmed Bayoumy Bayoumy
Ahmed Bayoumy Bayoumy
MSMelek Simsek
Melek Simsek
MSMargien L. Seinen
Margien L. Seinen
CMChris J.J. Mulder
Chris J.J. Mulder
AAAzhar Ansari
Azhar Ansari
NBNanne De Boer
Nanne De Boer
Introduction: In the 1950s, thioguanine (TG), a thiopurine-derivative together with azathioprine (AZA) and mercaptopurine (MP), were developed for the treatment of childhood leukemia. Over the years, the use of TG was also explored for other, mainly immune-mediated and inflammatory, diseases such as in the field of dermatology and rheumatology (e.g. psoriasis, systemic lupus erythematosus (SLE)) and gastroenterology and hepatology (e.g. inflammatory bowel diseases (IBD), autoimmune hepatitis). Areas covered: This review provides a comprehensive overview of all the clinical uses of TG and describes its mechanism of action, pharmacokinetic/pharmacodynamic features, and toxicity. Expert opinion: Thioguanine has shown beneficial clinical effects in hematological (particularly leukemia) and several immune-inflammatory diseases including psoriasis, SLE, polycythemia vera, Churg-Strauss syndrome, IBD, collagenous sprue, refractory celiac disease, and autoimmune hepatitis. Thioguanine is not effective in treating solid-cancers. At relatively low dosages, i.e. 0.2– 0.3mg/kg/day or 20 mg/day, TG has a favorable risk–benefit ratio and is a safe and effective drug in the long-term treatment of amongst other IBD patients. Thioguanine toxicity, especially myelotoxicity, and hepatotoxicity, including nodular regenerative hyperplasia (NRH) of the liver, is limited when dosed adequately. The occurrence of NRH appears dose-dependent and has been especially described during high dose TG above 40 mg/day.

20 May 2019 in European Archives of Oto-Rhino-Laryngology
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ABAhmed Bayoumy Bayoumy
Ahmed Bayoumy Bayoumy
JRJ. A. de Ru
J. A. de Ru
Acute hearing loss can have a major impact on a patient’s life. This holds true for both acute acoustic trauma (AAT) and idiopathic sudden sensorineural hearing loss (ISSHL), two devastating conditions for which no highly effective treatment options exist. This narrative review provides the rationale and evidence for HBOT in AAT and ISSHL.

10 October 2025 in Journal of Crohn's and Colitis
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Journal Article
Open access
ABAhmed Bayoumy Bayoumy
Ahmed Bayoumy Bayoumy
LCLindsay M Clarke
Lindsay M Clarke
PDParakkal Deepak
Parakkal Deepak
ADAakash Desai
Aakash Desai
PSPriya Sehgal
Priya Sehgal
NBNanne K H de Boer
Nanne K H de Boer
Background: Prior studies showed worse outcomes in obese inflammatory bowel disease (IBD) patients, especially those related to hospitalizations, surgery, and steroid-free remission. Glucagon-like peptide-1 receptor agonists (GLP1-RAs) have demonstrated significant metabolic benefits for patients with type 2 diabetes mellitus (T2DM) and obesity. Hence, GLP1-RAs may improve clinical outcomes in patients with IBD, especially those with obesity. The objective was to systematically evaluate the impact of GLP1-RAs on clinical outcomes in patients with IBD. Methods: A comprehensive literature search was performed using the databases PubMed, Embase, Web of Science, and Cochrane Library from inception to March 15, 2025. Studies reporting outcomes related to GLP1-RAs in patients with IBD were included. Primary outcomes included weight loss and various IBD-related co-endpoints such as hospitalizations, surgery, corticosteroid use, and advanced therapy initiation. Findings: In total, 11 studies with 16 242 patients with IBD treated with GLP1-RAs were included. Weight loss was achieved using semaglutide (−9.6 kg, 95% confidence interval [CI]: −12.0; −7.2), liraglutide (−9.4 kg, 95% CI: −13.0; −5.8), and tirzepatide (−11.8 kg, 95% CI: −18.3; −5.4) after 3 months of follow-up. In meta-analyses, GLP1-RAs were associated with lower risk of surgery for effect sizes (logHR: 0.61 [95% CI: 0.44-0.84], I 2 = 0%) and event frequencies (odds ratio [OR]: 0.46 [95% CI: 0.32-0.67], I 2 = 42%). Sensitivity analysis for body mass index (BMI) showed a lower risk of hospitalizations and surgery in patients with obesity (BMI ≥ 30). Interpretation: Patients with IBD and obesity using GLP1-RAs were able to achieve significant weight loss and had lower risks of surgery and hospitalizations. Our findings require confirmation in prospective trials of GLP1-RAs in IBD.

6 September 2021 in European Journal of Drug Metabolism and Pharmacokinetics
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ABAhmed Bayoumy Bayoumy
Ahmed Bayoumy Bayoumy
FCFemke Crouwel
Femke Crouwel
NCNripen Chanda
Nripen Chanda
TFTimothy H. J. Florin
Timothy H. J. Florin
HBHans J. C. Buiter
Hans J. C. Buiter
NBNanne K. H. de Boer
Nanne K. H. de Boer
Thiopurines (mercaptopurine, azathioprine and thioguanine) are well-established maintenance treatments for a wide range of diseases such as leukemia, inflammatory bowel disease (IBD), systemic lupus erythematosus (SLE) and other inflammatory and autoimmune diseases in general. Worldwide, millions of patients are treated with thiopurines. The use of thiopurines has been limited because of off-target effects such as myelotoxicity and hepatotoxicity. Therefore, seeking methods to enhance target-based thiopurine-based treatment is relevant, combined with pharmacogenetic testing. Controlled-release formulations for thiopurines have been clinically tested and have shown promising outcomes in inflammatory bowel disease. Latest developments in nano-formulations for thiopurines have shown encouraging pre-clinical results, but further research and development are needed. This review provides an overview of novel drug delivery strategies for thiopurines, reviewing modified release formulations and with a focus on nano-based formulations.

20 July 2024 in Clinical Pharmacokinetics
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Journal Article
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ABAhmed Bayoumy Bayoumy
Ahmed Bayoumy Bayoumy
AAA. R. Ansari
A. R. Ansari
CMC. J. J. Mulder
C. J. J. Mulder
KSK. Schmiegelow
K. Schmiegelow
TFTimothy Florin
Timothy Florin
NBN. K. H. De Boer
N. K. H. De Boer
Background and Objective Thioguanine (TG), azathioprine (AZA), and mercaptopurine (MP) are thiopurine prodrugs commonly used to treat diseases, such as leukemia and inflammatory bowel disease (IBD). 6-thioguanine nucleotides (6-TGNs) have been commonly used for monitoring treatment. High levels of 6-TGNs in red blood cells (RBCs) have been associated with leukopenia, the cutoff levels that predict this side effect remain uncertain. Thiopurines are metabolized and incorporated into leukocyte DNA. Measuring levels of DNA-incorporated thioguanine (DNA-TG) may be a more suitable method for predicting clinical response and toxicities such as leukopenia. Unfortunately, most methodologies to assay 6-TGNs are unable to identify the impact of NUDT15 variants, effecting mostly ethnic populations (e.g., Chinese, Indian, Malay, Japanese, and Hispanics). DNA-TG tackles this problem by directly measuring thioguanine in the DNA, which can be influenced by both TPMT and NUDT15 variants. While RBC 6-TGN concentrations have traditionally been used to optimize thiopurine therapy due to their ease and affordability of measurement, recent developments in liquid chromatography–tandem mass spectrometry (LC–MS/MS) techniques have made measuring DNA-TG concentrations in lymphocytes accurate, reproducible, and affordable. The objective of this systematic review was to assess the current evidence of DNA-TG levels as marker for thiopurine therapy, especially with regards to NUDT15 variants. Methods A systematic review and meta-analysis were performed on the current evidence for DNA-TG as a marker for monitoring thiopurine therapy, including methods for measurement and the illustrative relationship between DNA-TG and various gene variants (such as TPMT, NUDT15, ITPA, NT5C2, and MRP4). PubMed and Embase were systematically searched up to April 2024 for published studies, using the keyword “DNA-TG” with MeSH terms and synonyms. The electronic search strategy was augmented by a manual examination of references cited in articles, recent reviews, editorials, and meta-analyses. A meta-analysis was performed using R studio 4.1.3. to investigate the difference between the coefficients (Fisher’s z-transformed correlation coefficient) of DNA-TG and 6-TGNs levels. A meta-analysis was performed using RevMan version 5.4 to investigate the difference in DNA-TG levels between patients with or without leukopenia using randomized effect size model. The risk of bias was assessed using the Newcastle–Ottowa quality assessment scale. Results In this systematic review, 21 studies were included that measured DNA-TG levels in white blood cells for either patients with ALL (n = 16) or IBD (n = 5). In our meta-analysis, the overall mean difference between patients with leukopenia (ALL + IBD) versus no leukopenia was 134.15 fmol TG/µg DNA [95% confidence interval (CI) (83.78–184.35), P < 0.00001; heterogeneity chi squared of 5.62, I2 of 47%]. There was a significant difference in DNA-TG levels for patients with IBD with and without leukopenia [161.76 fmol TG/µg DNA; 95% CI (126.23–197.29), P < 0.00001; heterogeneity chi squared of 0.20, I2 of 0%]. No significant difference was found in DNA-TG level between patients with ALL with or without leukopenia (57.71 fmol TG/µg DNA [95% CI (− 22.93 to 138.35), P < 0.80]). DNA-TG monitoring was found to be a promising method for predicting relapse rates in patients with ALL, and DNA-TG levels are likely a better predictor for leukopenia in patients with IBD than RBC 6-TGNs levels. DNA-TG levels have been shown to correlate with various gene variants (TPMT, NUDT15, ITPA, and MRP4) in various studies, points to its potential as a more informative marker for guiding thiopurine therapy across diverse genetic backgrounds. Conclusions This systematic review strongly supports the further investigation of DNA-TG as a marker for monitoring thiopurine therapy. Its correlation with treatment outcomes, such as relapse-free survival in ALL and the risk of leukopenia in IBD, underscores its role in enhancing personalized treatment approaches. DNA-TG effectively identifies NUDT15 variants and predicts late leukopenia in patients with IBD, regardless of their NUDT15 variant status. The recommended threshold for late leukopenia prediction in patients with IBD with DNA-TG is suggested to be between 320 and 340 fmol/µg DNA. More clinical research on DNA-TG implementation is mandatory to improve patient care and to improve inclusivity in thiopurine treatment. Graphical Abstract