Hamdallah Zedan

• PhD
• Professor at Cairo University

Background: Shiga toxin-producing Escherichia coli (STEC) has been identified as an important etiologic agent of human disease in Egypt. Aims: To investigate the occurrence and describe the characterization as well as prevalence of STEC in Greater Cairo hospitals as well as molecular characterization of virulence and resistance genes. Methods: Four...

Purpose: Typhoid remains a major health problem, especially in the developing world. Furthermore, the emergence of multidrug-resistant and extensively drug-resistant strains of Salmonella typhi added a sense of urgency to develop more effective typhoid vaccines, one of which is bacterial ghosts (BGs), prepared by both genetic and chemical means. T...

A comprehensive assessment of the literature on strategies for the detection and removing endotoxin from biotechnological preparations was conducted. This study highlighted the brief history of endotoxin. After that, a review of endotoxin's chemical and physical features, as well as its pathophysiological consequences when the body is exposed to LP...

MMR vaccine is a common vaccine that contains oncolytic viruses (Measles, Mumps, and Rubella) and could be used as a potential anti-cancer treatment. In this study, we assessed the anti-tumor activity of the MMR vaccine against Ehrlich ascites carcinoma (EAC) solid tumor induced in mice. The in vitro assay showed that vaccine IC50 in EAC was approx...

Sorafenib, an oral multiple kinase inhibitor, is the standardized treatment for hepatocellular carcinoma (HCC). One strategy to improve HCC therapy is to combine agents that target key signaling pathways. In this study we set out to investigate the effect of combining sorafenib with either bevacizumab (anti-VEGF), panitumumab (anti-EGFR) or ramucir...

Possible applicability of controlled temperature chain (CTC) for selected antisera and vaccines was evaluated. Bivalent oral polio vaccine (OPV), hepatitis B vaccine (HepB vaccine; monovalent and combined) and antisera (lyophilized and liquid scorpion-antivenom and liquid snake-antivenom) were tested. Samples were stored at accelerated (35 ± 5 °C)...

Purpose: In the present study, whole diphtheria toxin (dt) and fragment B (dtb) genes from Corynebacterium diphtheriae Park William were cloned into Escherichia coli, the purified expressed proteins were evaluated for ultimately using as a candidate vaccine. Materials and methods: The dt and dtb genes were isolated from bacterial strain ATCC (Am...

Quorum sensing (QS) represents a major target for reducing bacterial pathogenicity and antibiotic resistance. This study identifies bergamot and aspidosperma as new potential sources of anti-QS agents. We investigated the anti-QS activity of plant materials on both Chromobacterium violaceum and Pseudomonas aeruginosa. Initially, we determined the m...

The biological fitness cost of antibiotic resistance is a key parameter in determining the rate of appearance and spread of antibiotic-resistant bacteria in Egypt. Our study aimed to investigate the prevalence of antibiotic resistance among Escherichia coli clinical isolates from Greater Cairo area hospitals. A total of 537 clinical isolates were r...

Background Immunogenicity is a major challenge in drug development and patient care. Clinicians and regulators are familiar with immunogenicity concerns of monoclonal antibody (mAb) therapeutics, growth factors and enzyme replacements. Although most small therapeutic molecules are unlikely to trigger undesirable immunogenic responses against themse...

Background Obesity and its related diseases are increasing worldwide. One of the best therapeutic strategies for obesity management is through the inhibition of pancreatic lipase (PL) enzyme. So far orlistat is the only FDA approved PL inhibitor, but with unpleasant side effects. New efficacious anti-obesity drugs are needed to achieve a successful...

Parenterally administered snake antivenom immunoglobulins are the only specific treatment for envenoming by snakebites. Endotoxin removal is a necessary part of good manufacturing practice for antivenom products to avoid life-threatening consequences associated with injecting endotoxin-contaminated product. Optimization of pH is an essential factor...

Staphylococcus aureus is a pathogen associated with community-acquired and healthcare-associated infections, and is known for rapid acquisition of resistance to multiple antibiotics. Staphylococcus epidermidis is another staphylococcal species commonly seen as a commensal, but may cause opportunistic infections. These two closely related species ma...

Staphylococcus aureus is a pathogen associated with community-acquired and healthcare-associated infections, and is known for rapid acquisition of resistance to multiple antibiotics. Staphylococcus epidermidis is another staphylococcal species commonly seen as a commensal, but may cause opportunistic infections. These two closely related species ma...

Snake antivenoms are the only definitive management of snake envenoming’s. Endotoxin contamination is a serious threat to the safety of parenteral drugs. A greater understanding of the nature of LAL-Test interferences and the use permissible dilution has minimized enhancement problems. Common interference mechanisms include suboptimal pH, enzyme or...

Objective The objective of this work was to isolate bacteria from Red Sea invertebrates, determine their antimicrobial activity, and screen for the biosynthetic gene clusters [polyketides (PKs) and nonribosomal peptides (NRPs)] which could be involved in the production of bioactive secondary metabolites. Result Eleven different samples of marine i...

The reference values of human semen, published in the WHO's latest edition in 2010, were lower than those previously reported. The objective of this study was to evaluate reference values of standard semen parameters in fertile Egyptian men. This cross-sectional study included 240 fertile men. Men were considered fertile when their wives had recent...

Background/aim Calcium phosphate (CAP) and aluminum phosphate (alum) compounds have been approved as vaccine adjuvants for humans. The present study aimed to study the ultrastructural and morphometric effect of both aluminum phosphate (alum) and CAP nanoparticle adjuvant. Materials and methods Eighteen Swiss albino mice were used in the experiment...

Snake bites represent a serious public health problem particularly in ruralareas worldwide. Antitoxic sera preparations are antibodies from immunized animals and are considered to be the only treatment option. The purification of antivenom antibodies should aim at obtaining products of consistent quality,safety, efficacy and adhering to the GMP pri...

Snake bites represent a serious public health problem, particularly in rural areas worldwide. Antitoxic sera preparations are antibodies from immunized animals and are considered to be the only treatment option. The purification of antivenom antibodies should aim at obtaining products of consistent quality, safety, efficacy, and adherence to good m...

Snake bites represent a serious public health problem particularly in rural areas worldwide. Antitoxic sera preparations are antibodies from immunized animals and are considered to be the only treatment option. The purification of antivenom antibodies should aim at obtaining products of consistent quality, safety, efficacy and adhering to the GMP p...

The present study aim at studying the histological effects of both aluminum phosphate (Alum) and calcium phosphate (CAP) nanoparticles adjuvant in parallel with their potentials as adjuvant and the related immune response to tetanus toxoid vaccine adsorbed on both of them. Ninety Swiss albino mice were used in the experiment (50% adults and 50% juv...

In the present study, a novel pre-miniproinsulin analogue was designed to have a short 9 residue sequence replacing the 35 residue C-chain, one lysine and one arginine added to the C-terminus of the B-chain in combination with glycine and arginine substitution at A21 and B29, respectively, and a 16-residue fusion partner comprising the pentapeptide...

Effectiveness of many antibiotics has been remarkably decreased due to bacterial resistance. the present work aims to explore a novel antimicrobial nanocomposite with greater efficacy against resistant bacteria. Tobramycin-silver nanocomposite was synthesized and characterized by Transmission Electron Microscopy, UV-VIS Spectroscopy, Zetasizer and...

The present study aim at studying the histological effects of both aluminum phosphate (Alum) and calcium phosphate (CAP) nanoparticles adjuvant in parallel with their potentials as adjuvant and the related immune response to tetanus toxoid vaccine adsorbed on both of them. Ninety Swiss albino mice were used in the experiment (50% adults and 50% juv...

Methicillin-resistant Staphylococcus aureus (MRSA) is a persistent problem in community and health care settings. Fluoroquinolones are among the drugs of choice used to treat MRSA infections. This study aims to identify different mechanisms of fluoroquinolne resistance in local MRSA random sampling isolates in Cairo, Egypt. A total of 94 clinical i...

Leprosy is a chronic infectious disease characterized by a broad spectrum of clinical forms depending on the patient's immune response, in particular cell-mediated immune response. Cytokines can play a role in the cell-mediated immune response. Serum levels of interferon-gamma (IFN-gamma), interleukin-2 (IL-2), interleukin-2 receptor (IL-2R), inter...

Multidrug therapy (MDT) causes a decrease in the bacterial burden in leprosy patients. Does the decrease in the antigenic stimulation of the immune system have an effect on cytokine production? The effect of treatment on serum cytokines was evaluated in 36 leprosy patients and 35 reactional leprosy patients and compared with that in 20 age- and sex...

Whole broth cultures, washed mycelia and non-germinating spores of 13 aspergilli scored from among 91 moulds isolated from soil and air transformed lucanthone (I) into three to five products with increased polarity. Biotransformations brought about by actively growing cultures were also performed by washed mycelia and non-germinating spores of the...

Unter optimalen Bedingungen werden die Aminosäuren (Ia)-(II) mit Nicotinsäureazid (II) zu den N-Nicotinoyl-Derivaten (IIIa)-(IIIl) umgesetzt; aus L-Ornithin (Im) bzw. L-Lysin (In) erhält man die Nα,Nδ- bzw. Nα,Nε-diacylierten Säuren (IIIm) bzw. (IIIn).

An ascogenous yeast with high potentialities for L-glutaminase and L-asparaginase formation was isolated from Egyptian soils by the application of the culture enrichment method. The organism, identified as Pichia polymorpha, was obtained through the enrichment of soil samples with a simple medium containing 0.5% L-glutaminase as a major carbon and...

Some of the factors which influence fermentation of progesterone by the non-germinating spores of a local isolate ofF. solani have been studied in an attempt to improve the yield of the pharmaceutically useful product androstadienedione. The optimum conditions for the spore-mediated fermentation were defined as: a minimum spore concentration of 2×1...

Some of the factors which influence the transformation of progesterone by non-germinating spores of C. radicicola have been studied in an attempt to suppress lactonization and thus improve the yield of the pharmaceutically useful product; androstadienedione. The transformation was found not to require preinduction of the spores, a source of energy...

Cylindrocarpon radicicola (ATCC 11011) and Fusarium solani (a local isolate) converted progesterone into androsta–1,4–diene–3,17–dione (androstadienedione) and 1–dehydrotestololactone. In the mycelial fermentation by C. radicicola both products could be demonstrated as long as there is progesterone in the medium, but as soon as all progesterone was...

The mycelia of a species of Aspergillus (isolated from the soil in Western Nigeria and tentatively identified as a member of the Niger group) transformed progesterone into 11 α-hydroxyprogesterone and six other unidentified products, while its spores transformed the same steroid to 11 α-hydroxyprogesterone only. Isolation and identification of the...

Washed, progesterone-induced mycelium of Fusarium solani transformed 17α-hydroxy-4-pregnene-3,20-dione (17α-hydroxyprogesterone) into its 1-dehydro analogue, 1,4-androstadiene-3, 17-dione (androstadienedione), and traces of 17β-hydroxy-1, 4-androstadien-3-one (1-dehydrotestosterone) and 17α-oxa-androsta-1,4-diene-3, 17-dione (1-dehydrotestololacton...

The spores of a strain of Fusarium solani 1-dehydrogenate ring A and cleave the 17beta-acetyl side chain of 17alpha-hydroxypregn-4-ene-3,20-dione (17alpha-hydroxyprogesterone) to give 17alpha-hydroxypregna-1,4-diene-3,20-dione (the 1-dehydro analogue) and little androsta-1,4-diene-3,4-diene-3,17-dione (androstadienedione). A 4-h lag period is obser...

The spores of a strain of Fusarium solani 1-dehydrogenate ring A and cleave the 17β-acetyl side chain of 17α-hydroxypregn-4-ene-3,20-dione (17α-hydroxyprogesterone) to give 17α-hydroxypregna-1,4-diene-3,20-dione (the 1-dehydro analogue) and little androsta-1,4-diene-3,4-diene-3,17-dione (androstadienedione). A 4-h lag period is observed in the cour...

The spores of Fusarium solani reduced the C(2)-carbonyl group, 1-dehydrogenated ring "A" and cleaved the side chain of 16alpha, 17alpha-oxidopregn-4-ene-3, 20-dione (16alpha, 17alpha-oxidoprogesterone)(I) to give the following products: 20alpha-hydroxy-16alpha, 17alpha-oxidopregn-4-en-3-one(II); 20alpha-hydroxy-16alpha, 17alpha-oxidopregna-1, 4-die...

The spores of Fusarium solani reduced the C2-carbonyl group, 1-dehydrogenated ring “A” and cleaved the side chain of 16α, 17α-oxidopregn-4-ene-3, 20-dione (16α, 17α-oxidoprogesterone)(I) to give the following products: 20α-hydroxy-16α, 17α-oxidopregn-4-en-3-one(II); 20α-hydroxy-16α, 17α-oxidopregna-1, 4-dien-3-one(III); 16α-hydroxy-17a-oxa-androsta...

A new technique for investigating steroid biotransformations involving the use of glucose-treated Silica Gel G thin-layer chromatography plates spotted with fungal spores and steroid substrates is described. The conversion is followed by the detection and identification of steroid metabolites and is carried out on single plates by using the spores...

A new technique for investigating steroid biotransformations involving the use of glucose-treated Silica Gel G thin-layer chromatography plates spotted with fungal spores and steroid substrates is described. The conversion is followed by the detection and identification of steroid metabolites and is carried out on single plates by using the spores...

Résumé en français. Thèse--Université de Montréal. "Thèse présentée à la Faculté des études supérieures en vue de l'obtention du grade Philosophiae doctor (sciences pharmaceutiques)." Bibliogr.: f. [178]-192.