John Guardiola

Dr. John Guardiola


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

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

Representative Publications

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3 September 2024 in American Journal of Gastroenterology
Verified
Journal Article
Closed access
ABAzizullah Beran
Azizullah Beran
TATarek Aboursheid
Tarek Aboursheid
AAAdel Hajj Ali
Adel Hajj Ali
HAHashem N Albunni
Hashem N Albunni
MMMouhand Mohamed
Mouhand Mohamed
JGJohn Guardiola
John Guardiola
INTRODUCTION: Inadequate bowel preparation (IBP) before colonoscopy remains a common problem. This meta-analysis aimed to assess the risk factors associated with IBP. METHODS: We searched multiple databases for studies that assessed risk factors for IBP after adjustment and reported the data as adjusted odds ratios with 95% confidence intervals. Meta-analyses were conducted using a random-effects model, and pooled adjusted odds ratios for risk factors reported in ≥ 3 studies were constructed. RESULTS: One hundred fifty-four studies with 358,257 participants were included. We analyzed 48 unique risk factors. Sociodemographic predictors of IBP were Medicaid insurance, obesity, current tobacco use, age ≥ 65 years, Black race, low education level, male sex, and unmarried status. Comorbidity-related predictors of IBP were any psychiatric disease, cirrhosis, American Society of Anesthesiologists (ASA) class ≥ 3, poor functional status, constipation, diabetes, previous abdominopelvic surgery, and hematochezia. Medication-related predictors of IBP were tricyclic antidepressants, antidepressants, opioids, nontricyclic antidepressants, and calcium channel blockers. Preparation/procedure-related predictors of IBP were brown liquid rectal effluent, any incomplete bowel preparation (BP) intake, lack of split-dose BP, increased BP-to-defecation interval, any nonadherence to dietary instructions, increased BP-to-colonoscopy interval, any BP intolerance, previous IBP, and inpatient status. Although afternoon colonoscopy was a predictor of IBP, subgroup analysis of prospective studies revealed no significant association. DISCUSSION: Our meta-analysis focused on adjusted risk factors to provide precise estimates of the most important risk factors for IBP. Our findings could help develop a validated prediction model to identify high-risk patients for IBP, improve colonoscopy outcomes, reduce the need for repeat colonoscopies, and reduce associated healthcare costs.

1 February 2019 in Journal of Biological Chemistry
Verified
Journal Article
Open access
PDF file
JAJim J. Aloor
Jim J. Aloor
KAKathleen M. Azzam
Kathleen M. Azzam
JGJohn Guardiola
John Guardiola
KGKymberly M. Gowdy
Kymberly M. Gowdy
JMJennifer H. Madenspacher
Jennifer H. Madenspacher
MFMichael B. Fessler
Michael B. Fessler
Toll-like Receptors (TLRs) are pathogen-recognition receptors that trigger the innate immune response. Recent reports have identified accessory proteins that provide essential support to TLR function through ligand delivery and receptor trafficking. Herein, we introduce leucine-rich repeats (LRR) and calponin homology containing 4 (Lrch4) as a novel TLR accessory protein. Lrch4 is a membrane protein with 9 LRRs in its predicted ectodomain. It is widely expressed across murine tissues, and has two expression variants that are both regulated by lipopolysaccharide (LPS). Predictive modeling indicates that Lrch4 LRRs conform to the horseshoe-shaped structure typical of LRRs in pathogen-recognition receptors, and that the best structural match in the protein database is to the variable lymphocyte receptor of the jawless vertebrate, hagfish. Silencing Lrch4 attenuates cytokine induction by LPS and multiple other TLR ligands and dampens the in vivo innate immune response. Lrch4 promotes proper docking of LPS in lipid raft membrane microdomains. We provide evidence that this is through regulation of lipid rafts as Lrch4 silencing reduces cell surface gangliosides, a metric of raft abundance, as well as expression and surface display of CD14, a raft-resident LPS co-receptor. Taken together, we identify Lrch4 as a broad-spanning regulator of the innate immune response and a potential molecular target in inflammatory disease.

10 March 2022 in Journal of Hepatology
Verified
Journal Article
Closed access
JGJohn Guardiola
John Guardiola
CLCraig Lammert
Craig Lammert
ETEvgenia Teal
Evgenia Teal
NCNaga Chalasani
Naga Chalasani

12 February 2025 in American Journal of Gastroenterology
Verified
Journal Article
Closed access
ABAzizullah Beran
Azizullah Beran
TNTarek Nayfeh
Tarek Nayfeh
AAAya Akhras
Aya Akhras
DRDaryl Ramai
Daryl Ramai
MMMouhand Mohamed
Mouhand Mohamed
DRDouglas K. Rex
Douglas K. Rex
INTRODUCTION: The impact of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on colonoscopy bowel preparation is unclear. METHODS: We searched multiple databases for studies comparing bowel preparation quality between GLP-1RA users and the control group. Using a random-effects model, we calculated pooled odds ratios and mean differences with 95% confidence intervals (CIs). Inadequate bowel preparation (IBP) rate was the primary outcome, and Boston Bowel Preparation Scale mean score was the secondary outcome. RESULTS: Five studies with 10,833 patients (n = 5,434 GLP-1RAs vs n = 5,399 control) were included. The IBP rate was higher in the GLP-1RAs group compared with the control group (odds ratios 2.10, 95% CI 1.41–3.13, P = 0.0003). Furthermore, the mean Boston Bowel Preparation Scale score was lower in the GLP1-RAs group compared with the control group (mean differences −0.34; 95% CI −0.51, −0.17; P = 0.0001). DISCUSSION: Our findings suggest that using GLP-1RA increases the risk of IBP.

23 September 2024 in Clinical Gastroenterology and Hepatology
Verified
Journal Article
Closed access
JGJohn Guardiola
John Guardiola
JAJoseph C. Anderson
Joseph C. Anderson
TKTonya Kaltenbach
Tonya Kaltenbach
HPHeiko Pohl
Heiko Pohl
DRDouglas K. Rex
Douglas K. Rex

21 May 2024 in Endoscopy International Open
Verified
Journal Article
Open access
PDF file
JGJohn Guardiola
John Guardiola
DRDouglas K. Rex
Douglas K. Rex
CTChristopher C. Thompson
Christopher C. Thompson
JMJeffrey Mosko
Jeffrey Mosko
MRMarvin Ryou
Marvin Ryou
DRDaniel von Renteln
Daniel von Renteln
Background and study aims Endoscopic through-the-scope clips (TTSC) are used for hemostasis and closure. We documented the performance of a new TTSC with anchor prongs. Patients and methods We conducted a prospective case series of the new TTSC in 50 patients with an indication for endoscopic clipping at three hospitals in the United States and Canada. Patients were followed for 30 days after the index procedure. Outcomes included defect closure and rate of serious adverse events (SAEs) related to the device or procedure. Results Fifty patients had 56 clipping procedures. Thirty-four procedures were clipping after endoscopic mucosal resection (EMR) in the colon (33) or stomach (1), 16 after polypectomy, two for hemostasis of active bleeding, and one each for fistula closure, per-oral endoscopic myotomy mucosal closure, or anchoring a feeding tube. Complete defect closure was achieved in 32 of 33 colon EMR defects and 21 of 22 other defects. All clips were placed per labeled directions for use. In 41 patients (82.0%), prophylaxis of delayed bleeding was reported as an indication for endoscopic clipping. There were three instances of delayed bleeding. There were no device-related SAEs. The only technical difficulty was one instance of premature clip deployment. Conclusions A novel TTSC with anchor prongs showed success in a range of defect closures, an acceptable safety profile, and low incidence of technical difficulties.