Ashraf A. Khalil

Heat shock proteins in oncology: diagnostic biomarkers or therapeutic targets?

Heat shock proteins (HSP) are a family of proteins induced in cells exposed to different insults. This induction of HSPs allows cells to survive stress conditions. Mammalian HSPs have been classified into six families according to their molecular size: HSP100, HSP90, HSP70, HSP60, HSP40 and small HSPs (15 to 30kDa) including HSP27. These proteins act as molecular chaperones either helping in the refolding of misfolded proteins or assisting in their elimination if they become irreversibly damaged. In recent years, proteomic studies have characterized several different HSPs in various tumor types which may be putative clinical biomarkers or molecular targets for cancer therapy. This has led to the development of a series of molecules capable of inhibiting HSPs. Numerous studies speculated that over-expression of HSP is in part responsible for resistance to many anti-tumor agents and chemotherapeutics. Hence, from a pharmacological point of view, the co-administration of HSP inhibitors together with other anti-tumor agents is of major importance in overcoming therapeutic resistance. In this review, we provide an overview of the current status of HSPs in autoimmune, cardiovascular, and neurodegenerative diseases with special emphasis on cancer.

Antibacterial activity of some wild medicinal plants collected from western Mediterranean coast, Egypt: Natural alternatives for infectious disease treatment

Traditional medicine has a key role in health care worldwide. Obtaining scientific information about the efficacy and safety of the wild plants grown in western Mediterranean coast of Egypt is one of our research goals. In this study, 10 wild plants namely Mesembryanthemum crystallinum, Blackiella aellen, Arthrocnemon glaucum, Atriplex halimus, Thymelaea hirsute, Carduus getulus, Nicotiana glauca, Alhagi maurorum, Atractylis carduus and Echinops spinosissimus were collected from El-Hammam, Burg El Arab and Bahig regions located along the Western Mediterranean coast of Egypt. Hexane and methanol extracts of fresh aerial parts of the plants were screened in vitro for antimicrobial activity against 15 Gram positive and negative pathogenic bacteria. Both methanol and hexane plant extracts showed strong antibacterial activity against at least two pathogenic microorganisms tested. However, hexane extracts generally showed lower activity against microorganisms compared to methanol extracts. The microorganisms’ susceptibility to different extracts did not correlate with the susceptibility or resistance to a particular antibiotic. The results of this study thus support the medical usage of the studied plants and suggest that some of these plants possess antimicrobial properties that can be used to cure infectious diseases. Key words : Egyptian wild plants, antagonism, biological control, phytochemicals, multi-drug resistant.

Nutritional improvement of an Egyptian breed of mung bean by probiotic lactobacilli

Germination and/or fermentation processes for Egyptian breeds of mung seeds were carried out with three Lactobacillus strains namely, L. reuteri, L. case, and L. heleviticus. Results revealed increase in protein content, nitrogen solubility and in vitro digestibility for all treated mung meals. Treated mung proteins contained most of the essential amino acids in concentrations comparable to those recommended by the FAO/WHO, with the exception of the sulphur-containing amino acids. Trypsin inhibitor units (TIU) and phytate content of untreated MB were 6.98 TIU/mg dry sample and 5.61 mg phytate/g dry sample, respectively. Fermentation treatments were effective in decreasing the phytate content as well as reducing trypsin inhibitor activity, while L. casei was the most efficient probiotic culture in reducing those antinutritional factors. The combined treatment of germination and lactic fermentation utilizing Lactobacillus species is recommended process for enhancing the nutritional quality of legume protein.

Enhancement of Mechanical Properties, Microstructure, and Antimicrobial Activities of Zein Films Cross-Linked Using Succinic Anhydride, Eugenol, and Citric Acid

Zein constitutes about half of the endosperm proteins in corn. Recently, attempts have been made to utilize zein for food coatings and biodegradable materials, which require better physical properties, using chemical modification of zein. In this study, zein proteins were modified using citric acid, succinic anhydride, and eugenol as natural cross-linking agents in the wet state. The cross-linkers were added either separately or combined in increment concentrations (0.1, 0.2, 0.3, and 0.4%). The effects of those agents on the mechanical properties, microstructure, optical properties, infrared (IR) spectroscopy, and antibacterial activities of zein were investigated. The addition of cross-linking agents promoted changes in the arrangement of groups in zein film-forming particles. Regarding the film properties, incorporation of cross-linking agents into zein films prepared in ethanol resulted in two- to three-fold increases in tensile strength (TS) values. According to the Fourier-transform infrared (FTIR) spectra and Hunter parameters there were no remarkable changes in the structure and color of zein films. Transparency of zein films was decreased differentially according to the type and cross-linker concentration. The mechanical and optical properties of zein films were closely related to their microstructure. All cross-linked films showed remarkable antibacterial activities against Bacillus cereus ATCC 49064 and Salmonella enterica ATCC 25566. Food spoilage and pathogenic bacteria were affected in a film-dependent manner. Our experimental results show that even with partial cross-linking the mechanical properties and antipathogen activities of zein films were significantly improved, which would be useful for various industrial applications.

Metal chelate affinity precipitation: purification of (His)6-tagged lactate dehydrogenase using poly(vinylimidazole-co-N-isopropylacrylamide) copolymers

Affinity precipitation is a highly selective bioseparation method, which has been successfully used in the purification of various enzymes/proteins. The separation of (His)6-tagged lactate dehydrogenase ((His)6-LDH) was carried through affinity precipitation technique using thermoresponsive copolymer poly(vinylimidazole-co-N-isopropyl-acrylamide) (poly(VI-NIPAM)). Nearly quantitative recovery of (His)6-LDH has been achieved using Cu(II)- and Ni(II)-loaded poly(VI-NIPAM) with Cu(II)-poly(VI-NIPAM) being more efficient in enzyme precipitation than Ni(II)-poly(VI-NIPAM). Optimal precipitation of (His)6-LDH was achieved at pH 6 and pH 6.5–7.0 with Cu(II)-poly(VI-NIPAM) and Ni(II)-poly(VI-NIPAM), respectively. Furthermore, the enzyme was purified by affinity precipitation upto 3.5- and 3.1-fold with recoveries of 95 and 82% using Cu(II)- and Ni(II)-loaded copolymers, respectively.

Autohydrolysed Tilapia nilotica Fish Viscera as a Peptone Source in Bacteriocin Production

Fish processing generates large amounts of solid and liquid wastes. Many different by-products have been produced from fish processing wastes. Studies on solubilization of Bolti fish (Tilapia nilotica) viscera by endogenous enzymes at different pHs are described. Hydrolysis reactions were conducted with freshly thawed viscera utilizing an initial temperature gradient and terminated at various time points by heat inactivation of the enzymes. Various peptones obtained from hydrolysed visceral homogenates of Bolti fish residues showed their suitability for promoting the growth of lactic acid bacteria (mainly Lactobacillus sake Lb 706), microorganisms with particularly complex nutritional requirements especially peptidic sources. The assay of several treatments with L. sakei Lb 706, producer of the bacteriocin sakacin A, demonstrated that optimum conditions for biomass and bacteriocin production only imply a brief autohydrolysis at room temperature. The results showed that the Bolti fish hydrolysates gave remarkable results to those found in costly commercial media, specifically recommended for culturing and large-scale production of lactic acid bacteria.

Synthesis, characterization and antibacterial activity of biodegradable films prepared from Schiff bases of zein

Pure zein is known to be very hydrophobic, but is still inappropriate for coating and film applications because of their brittle nature. In an attempt to improve the flexibility and the antimicrobial activity of these coatings and films, Chemical modification of zein through forming Schiff bases with different phenolic aldhydes was tried. Influence of this modifications on mechanical, topographical, wetting properties and antimicrobial activity of zein films were evaluated. The chemical structure of the Schiff bases films were characterized by ATR-FTIR spectroscopy. The results indicate an improvement in mechanical properties with chemically modification of zein to form Schiff bases leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with slight influence on tensile strength. Plasticized zein films have similar initial contact angle (∼40°). An increase in reaction temperature and time increases film’s affinity towards water. As shown by contact angle measurements, a noticeable relation was found between film composition and the hydrophilicity. Surface topography also varied by forming Schiff bases, becoming rougher than zein-based films. The antibacterial activities of zein and Schiff bases of zein-based films were investigated against gram-positive bacteria (Listeria innocua, Listeria monocytogenes, Bacillus cereus and Clostridium sporogenes) and gram-negative bacteria (Escherichia coli, Yersinia enterocolitica and Salmonella enterica). It was found that the antibacterial activity of the Schiff bases-based films was more effective than that of zein-based films.

Oxidative stress induces idiopathic infertility in Egyptian males

The most common cause of male infertility is idiopathic. Oxidative stress (OS) would play a vital role in etiology of idiopathic male infertility because of its targeting to spermatozoa plasma membrane rich in polyunsaturated fatty acids. To examine OS effect on Egyptian men fertility, sperm samples were obtained from infertile idiopathic patients (25 to 35 years old). The samples were categorized into 4 groups: fertile group (n = 20); azospermia’s patients (n = 20); normospermic patients (n = 20) and oligospermic patients (n = 40). Induced OS was tracked by measuring the alteration in prooxidant level (TBARS) as well as activities of antioxidant enzymes superoxide dismutase (SOD), glutathione-Stransferase (GST), glutathione peroxide (GPX) and reduced glutathione (GSH). The TBARS levels were significantly high in infertile patients (within a range of 33.89 to 81.77%) compared to the healthy individuals. GST, SOD and GSH were significantly low in oligospermic patients by 33.33, 39.655 and 53.16%, respectively while GPX was higher by 87.5%. In azospermic patients, GSH and SOD activities were lower by 50% while GPX reached its maximum activity (93.75%). For normospermic patients with high immotile sperm, SOD activity was higher by 62.06% while both GSH and GPX were lower by 36.54 and 70.31%, respectively compared to the healthy individuals. Our results obviously emphasize the association of OS level in seminal plasma with the incidence and progression of the idiopathic infertility in infertile patients. Thus, seminal reactive oxygen species (ROS) would be used as a specific and sensitive biomarker for idiopathic male infertility. Key words : Idiopathic male infertility, azospermia, oligospermia, normospermia, oxidative stress, antioxidant enzymes, thiobarbituric acid reactive species.