Publications by authors named "Ahmad Madkour"

11 Publications

  • Page 1 of 1

Peroral endoscopic myotomy as treatment for Zenker's diverticulum (Z-POEM): a multi-center international study.

Esophagus 2021 Jul 2;18(3):693-699. Epub 2021 Jan 2.

Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, USA.

Background: Peroral endoscopic myotomy for the treatment of Zenker's diverticulum (Z-POEM) is a novel technique that has been described in several recent reports. This method utilizes the third space (submucosal layer) to create a tunnel to facilitate complete visualization of the septum and hence cutting it entirely. Conventional endoscopic septotomy carries the risk of recurrence due to incomplete visualization of the septum. While surgical correction is a risky and lengthy procedure in old comorbid patients with Zenker's diverticulum. The aim of this study is to assess the efficacy and safety of Z-POEM.

Methods: The study enrolled 24 patients diagnosed with Zenker's diverticulum (ZD) who underwent Z-POEM at seven independent endoscopy centers in five different countries.

Results: Mean patient age ± standard deviation (SD) was 74.3 ± 11 years. Most of the patients were males (n = 20, 83.3%); four (16.7%) were females. More than 50% of the patients (n = 14, 58.3%) had associated comorbidities. The mean size of the diverticula was 4 cm (range 2-7 cm). The Kothari-Haber Score was used to assess clinical symptoms; values ranged from 6 to 14 (median = 9). We achieved 100% technical success with a median procedure time of 61 min and no adverse events. Median hospital stay was 1 day (range 1-5 days). There is a significant reduction in the Kothari-Haber Score after Z-POEM (P < 0.0001). Technical success was achieved in 100% of the patients. Clinical success was achieved in 23/24 (95.8%) of the patients with a median follow-up of 10 months (range 6-24 months).

Conclusion: Z-POEM is a safe and effective modality for managing ZD.
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http://dx.doi.org/10.1007/s10388-020-00809-7DOI Listing
July 2021

Clinical features and laboratory characteristics of patients hospitalized with COVID-19: single centre report from Egypt.

J Infect Dev Ctries 2020 12 31;14(12):1352-1360. Epub 2020 Dec 31.

Endemic Medicine Department, Faculty of Medicine, Helwan University, Cairo, Egypt.

Introduction: The recently discovered novel coronavirus disease (COVID-19) has emerged in Wuhan, China, since January 2020. Egypt reported a low incidence of infection when compared with other countries. The aim of the study was to assess the characterization of COVID-19 infection among the Egyptian population.

Methodology: Data were collected from a single COVID-19 quarantine hospital in Cairo. A total number of 195 cases were included with their clinical, laboratory, and radiological data.

Results: Three different age groups behaved differently for COVD-19 infection. The pediatric age group was asymptomatic entirely, the middle age group (18-50 years) were asymptomatic in 53.3% of cases, while 77.9% of those above 50 years were symptomatic (p ≤ 0.001). The latter group had a high incidence of COVID-pneumonia in (83.1%), and moderate to critical presentations were encountered in 66.3% of them. Neutrophil to lymphocyte (N/L) ratio correlated directly with the age and case severity. C-reactive protein (CRP) and computed tomography scan chest (CT-chest) had added value on COVID-19 diagnosis in suspected cases.

Conclusions: In Egypt, patients above 50 years are at a higher risk for symptomatic COVID-19 infection and leaner for moderate to critical COVID-19 presentation. The triad of CT-chest, CRP, and N/L ratio could be an integrated panel for assessing disease severity.
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http://dx.doi.org/10.3855/jidc.13156DOI Listing
December 2020

Variceal recurrence 4 years post endoscopic band ligation in hepatitis C patients who achieved sustained virological response with oral direct-acting antiviral therapy.

J Viral Hepat 2021 02 9;28(2):279-287. Epub 2020 Nov 9.

Department of Hepatology and Gastroenterology, National Liver Institute, Menoufia University, Menoufia, Egypt.

Oral Direct-acting antivirals (DAAs) are safe, highly effective altering disease burden and prognosis in hepatitis C patients. Sustained virologic response (SVR) is achieved nowadays in more than 90% of the treated patients and related to the improvements in functions of the liver, fibrosis plus survival. Furthermore, portal hypertension is thought to be improved with achievement of virological response, parallel to the improvements in hepatic inflammation and fibrosis. We aimed to assess the recurrence rate of oesophageal varices by long-term follow-up in patients treated with different DAAs regimens who had achieved SVR. We studied 176 Child A cirrhotic HCV patients who achieved SVR after DAAs treatment and had a history of endoscopic oesophageal varices obliteration and were on maximum tolerated propranolol dose. They were subjected to follow-up upper gastrointestinal endoscopy repeated every 6 months for 4 years. Fifty-two patients (29.5%) had recurrence of oesophageal varices observed during the 4-years follow-up upper GIT endoscopy. On multivariate analysis, platelet count was the only significant variable, P-value = .007*. HbA1C, HOMA IR, BMI 1 and BMI 2 showed non-significant differences between the studied groups. By ROC analysis, we identified baseline platelet count of 96 000/µL with 100% sensitivity (95% confidence interval [CI] [91%-100%]) and 74% specificity (95% CI [65%-81%]). Spearman correlation showed a positive correlation between AFP, age, AST, Bilirubin, creatinine, INR. Patients who achieved SVR post DAAs showed a significant decrease in oesophageal varices recurrence post endoscopic obliteration. Baseline platelet count was found to be a strong independent predictor for oesophageal varices recurrence.
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http://dx.doi.org/10.1111/jvh.13426DOI Listing
February 2021

Liver transplantation in the era of COVID-19.

Arab J Gastroenterol 2020 Jun 12;21(2):69-75. Epub 2020 May 12.

Internal Medicine Department, Hepatogastroenterology Unit, Kasr Al-Ainy School Of Medicine, Cairo University, Cairo, Egypt.

Liver transplantation is considered the ultimate solution for patients with end-stage chronic liver disease or acute liver failure. Patients with liver transplant need special care starting from preoperative preparation, surgical intervention ending with postoperative care. Transplanted patients have to receive immunosuppressive therapy to prevent rejection. Such a state of immune suppression could predispose to different types of infections in liver transplant recipients. Currently, the world is suffering a pandemic caused by a new strain of the coronavirus family called COVID-19. Certain infection control precautions are needed to protect immunocompromised and vulnerable patients, including liver transplant candidates and recipients from acquiring COVID-19 infection. Restricting non-transplant elective surgical procedures, managing transplant patients in separate outpatient clinics, and in-patient wards can prevent transmission of infection both to patients and healthcare workers. Telemedicine can help in the triage of patients to screen for symptoms of COVID-19 before their regular appointment. Management of immunosuppressive therapy and drug-drug interactions in liver transplant recipients infected with COVID-19 should be cautiously practiced to prevent rejection and effectively treat the underlying infection. In this report, we are trying to summarize available evidence about different aspects of the management of liver transplant candidates and recipients in the era of COVID-19.
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http://dx.doi.org/10.1016/j.ajg.2020.04.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7214343PMC
June 2020

Synthetically simple, highly resilient hydrogels.

Biomacromolecules 2012 Mar 28;13(3):584-8. Epub 2012 Feb 28.

Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, United States.

Highly resilient synthetic hydrogels were synthesized by using the efficient thiol-norbornene chemistry to cross-link hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) polymer chains. The swelling and mechanical properties of the hydrogels were controlled by the relative amounts of PEG and PDMS. The fracture toughness (G(c)) was increased to 80 J/m(2) as the water content of the hydrogel decreased from 95% to 82%. In addition, the mechanical energy storage efficiency (resilience) was more than 97% at strains up to 300%. This is comparable with one of the most resilient materials known: natural resilin, an elastic protein found in many insects, such as in the tendons of fleas and the wings of dragonflies. The high resilience of these hydrogels can be attributed to the well-defined network structure provided by the versatile chemistry, low cross-link density, and lack of secondary structure in the polymer chains.
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http://dx.doi.org/10.1021/bm300015sDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4251582PMC
March 2012

End-functionalized ROMP polymers for Biomedical Applications.

Macromolecules 2010 May;43(10):4557-4561

Department of Polymer Science & Engineering, University of Massachusetts, Amherst, MA 01003, USA.

We present two novel allyl-based terminating agents that can be used to end-functionalize living polymer chains obtained by ring-opening metathesis polymerization (ROMP) using Grubbs' third generation catalyst. Both terminating agents can be easily synthesized and yield ROMP polymers with stable, storable activated ester groups at the chain-end. These end-functionalized ROMP polymers are attractive building blocks for advanced polymeric materials, especially in the biomedical field. Dye-labeling and surface-coupling of antimicrobially active polymers using these end-groups were demonstrated.
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http://dx.doi.org/10.1021/ma100330uDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3076928PMC
May 2010

Antimicrobial polymers prepared by ring-opening metathesis polymerization: manipulating antimicrobial properties by organic counterion and charge density variation.

Chemistry 2009 Nov;15(43):11715-22

Department of Polymer Science & Engineering, University of Massachusetts, Amherst, MA 01003, USA.

The synthesis and characterization of a series of poly(oxanorbornene)-based synthetic mimics of antimicrobial peptides (SMAMPs) is presented. In the first part, the effect of different organic counterions on the antimicrobial properties of the SMAMPs was investigated. Unexpectedly, adding hydrophobicity by complete anion exchange did not increase the SMAMPs' antimicrobial activity. It was found by dye-leakage studies that this was due to the loss of membrane activity of these polymers caused by the formation of tight ion pairs between the organic counterions and the polymer backbone. In the second part, the effect of molecular charge density on the biological properties of a SMAMP was investigated. The results suggest that, above a certain charge threshold, neither minimum inhibitory concentration (MIC90) nor hemolytic activity (HC50) is greatly affected by adding more cationic groups to the molecule. A SMAMP with an MIC90 of 4 microg mL(-1) against Staphylococcus aureus and a selectivity (=HC50/MIC90) of 650 was discovered, the most selective SMAMP to date.
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http://dx.doi.org/10.1002/chem.200900606DOI Listing
November 2009

Fast disinfecting antimicrobial surfaces.

Langmuir 2009 Jan;25(2):1060-7

Department of Polymer Science & Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA.

Silicon wafers and glass surfaces were functionalized with facially amphiphilic antimicrobial copolymers using the "grafting from" technique. Surface-initiated atom transfer radical polymerization (ATRP) was used to grow poly(butylmethacrylate)-co-poly(Boc-aminoethyl methacrylate) from the surfaces. Upon Boc-deprotection, these surfaces became highly antimicrobial and killed S. aureus and E. coli 100% in less than 5 min. The molecular weight and grafting density of the polymer were controlled by varying the polymerization time and initiator surface density. Antimicrobial studies showed that the killing efficiency of these surfaces was independent of polymer layer thickness or grafting density within the range of surfaces studied.
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http://dx.doi.org/10.1021/la802953vDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3748578PMC
January 2009

Synthetic mimic of antimicrobial peptide with nonmembrane-disrupting antibacterial properties.

Biomacromolecules 2008 Nov 14;9(11):2980-3. Epub 2008 Oct 14.

Department of Polymer Science and Engineering, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, USA.

Polyguanidinium oxanorbornene ( PGON) was synthesized from norbornene monomers via ring-opening metathesis polymerization. This polymer was observed to be strongly antibacterial against Gram-negative and Gram-positive bacteria as well as nonhemolytic against human red blood cells. Time-kill studies indicated that this polymer is lethal and not just bacteriostatic. In sharp contrast to previously reported SMAMPs (synthetic mimics of antimicrobial peptides), PGON did not disrupt membranes in vesicle-dye leakage assays and microscopy experiments. The unique biological properties of PGON, in same ways similar to cell-penetrating peptides, strongly encourage the examination of other novel guanidino containing macromolecules as powerful and selective antimicrobial agents.
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http://dx.doi.org/10.1021/bm800855tDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2646885PMC
November 2008

Antimicrobial polymers prepared by ROMP with unprecedented selectivity: a molecular construction kit approach.

J Am Chem Soc 2008 Jul 1;130(30):9836-43. Epub 2008 Jul 1.

Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA.

Synthetic Mimics of Antimicrobial Peptides (SMAMPs) imitate natural host-defense peptides, a vital component of the body's immune system. This work presents a molecular construction kit that allows the easy and versatile synthesis of a broad variety of facially amphiphilic oxanorbornene-derived monomers. Their ring-opening metathesis polymerization (ROMP) and deprotection provide several series of SMAMPs. Using amphiphilicity, monomer feed ratio, and molecular weight as parameters, polymers with 533 times higher selectivitiy (selecitviy = hemolytic concentration/minimum inhibitory concentration) for bacteria over mammalian cells were discovered. Some of these polymers were 50 times more selective for Gram-positive over Gram-negative bacteria while other polymers surprisingly showed the opposite preference. This kind of "double selectivity" (bacteria over mammalian and one bacterial type over another) is unprecedented in other polymer systems and is attributed to the monomer's facial amphiphilicity.
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http://dx.doi.org/10.1021/ja801662yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4106262PMC
July 2008

Infectious Disease: Connecting Innate Immunity to Biocidal Polymers.

Mater Sci Eng R Rep 2007 Aug;57(1-6):28-64

Polymer Science & Engineering Department, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003.

Infectious disease is a critically important global healthcare issue. In the U.S. alone there are 2 million new cases of hospital-acquired infections annually leading to 90,000 deaths and 5 billion dollars of added healthcare costs. Couple these numbers with the appearance of new antibiotic resistant bacterial strains and the increasing occurrences of community-type outbreaks, and clearly this is an important problem. Our review attempts to bridge the research areas of natural host defense peptides (HDPs), a component of the innate immune system, and biocidal cationic polymers. Recently discovered peptidomimetics and other synthetic mimics of HDPs, that can be short oligomers as well as polymeric macromolecules, provide a unique link between these two areas. An emerging class of these mimics are the facially amphiphilic polymers that aim to emulate the physicochemical properties of HDPs but take advantage of the synthetic ease of polymers. These mimics have been designed with antimicrobial activity and, importantly, selectivity that rivals natural HDPs. In addition to providing some perspective on HDPs, selective mimics, and biocidal polymers, focus is given to the arsenal of biophysical techniques available to study their mode of action and interactions with phospholipid membranes. The issue of lipid type is highlighted and the important role of negative curvature lipids is illustrated. Finally, materials applications (for instance, in the development of permanently antibacterial surfaces) are discussed as this is an important part of controlling the spread of infectious disease.
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http://dx.doi.org/10.1016/j.mser.2007.03.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2153456PMC
August 2007
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