Heba A. Hassan

Bio: Heba A. Hassan is an academic researcher from Minia University. The author has contributed to research in topics: Medicine & Chemistry. The author has an hindex of 15, co-authored 102 publications receiving 754 citations. Previous affiliations of Heba A. Hassan include Higher Education Academy & Ain Shams University.

Recent updates of fluoroquinolones as antibacterial agents.

Abstract: Fluoroquinolones remain one of the most important kind of antibacterial agents used nowadays. The emergence of more virulent and resistant strains of bacteria by the development of either mutated DNA-binding proteins or efflux pump mechanism for drugs is considered the main problem associated with the therapeutic use of these drugs. This situation participated in pushing researchers to design new fluoroquinolone derivatives, mainly with different substituents at C-7 to withstand these resistant strains of bacteria and to obtain a wider spectrum of activity including activity against anaerobic organisms. Conjugation of fluoroquinolones with substitutions such as 1,2,4-triazoles, alkyl oximes, flavonoids, aryl furans, benzofuroxans, metronidazoles or even other antibiotics such as neomycin-B produced derivatives that have a superior and wider spectrum of activity and better resistance than the classical fluoroquinolone agents. Addition of a hydroxamic acid moiety to fluoroquinolones also increased the activity against Proteus mirabilis, which represents one of the most resistant strains of bacteria in urinary tract infections. This review aims to highlight the recent updates made for fluoroquinolones for broadening the spectrum of activity to become active not only against resistant strains of bacteria but also against anaerobic pathogens.

SVC dynamic analytical model

Abstract: This paper presents a linear state-space model of a static var compensator (SVC). The model consists of three individual subsystem models: an ac system, an SVC model, and a controller model, linked together through d-q transformation. The issue of nonlinear susceptance-voltage term and coupling with a static frame of reference is resolved using an artificial rotating susceptance and linearizing its dependence on firing angle. The model is implemented in MATLAB and verified against PSCAD/EMTDC in the time and frequency domains. The verification demonstrates very good system gain accuracy in a wide frequency rangef <150 Hz, whereas the phase angle shows somewhat inferior matching above 25 Hz. It is concluded that the model is sufficiently accurate for many control design applications and practical stability issues. The model's use is demonstrated by analyzing the dynamic influence of the PLL gains, where the eigenvalue movement shows that reductions in gains deteriorate system stability.

Effect of some medicinal plant extracts on the oxidative stress status in Alzheimer's disease induced in rats.

Abstract: Background/aim Alzheimer's disease (AD) is a progressive neurodegenerative disorder. Increased oxidative stress has been shown to be a prominent and early feature in AD. Medicinal plants with antioxidant activities have been used traditionally in the treatment of several human diseases. The present study aims to investigate the effect of Salvia triloba and Piper nigrum plant extracts on the oxidative stress status in Alzheimer's disease induced in rats. Materials and methods 70 male rats were enrolled in this study and were classified into 7 groups (ten each). Group 1: control group, group 2: AD-induced rats by aluminum chloride, and served as positive control; group 3: AD group treated with Rivastigmine in a dose of 0.3 mg/kg b. wt. daily for three months; group 4 & 5: AD group treated with total extract of Salvia triloba in a dose of 750 or 375 mg/kg b. wt. respectively, daily for three months; group 6 & 7: AD group treated with total extract Piper nigrum in a dose of 187.5 or 93.75 mg/kg b. wt. respectively, daily for three months. After three months of treatment animals' sera and brain samples were collected. Malondialdehyde (MDA), nitric oxide (NO) and total antioxidant capacity (TAC) were determined in serum while superoxide dismutase (SOD) in erythrocyte. Brain samples were divided sagitally into two portions, the first portion was separated for determination of acetylcholine (Ach) and acetycholinesterase (AchE). The second portion was used for histopathological investigation. Results The results indicated that extracts of Salvia triloba and Piper nigrum as well as Rivastigmine showed significant increase in brain Ach, serum TAC and SOD and significant decreases in brain AchE, MDA and NO in AD-induced rats. Moreover, histological investigation of brain sections showing nearly normal histological structure of hippocampus. Treatment with Salvia triloba in a dose of 750 mg/kg b. wt. was more powerful in protection from Alzheimer's disease than Piper nigrum, as indicated by both biochemical and histopathological findings. Conclusion This study revealed that the treatment of AD-induced rats with Salvia triloba and Piper nigrum, total plant extracts significantly reduced the oxidative stress status and ameliorates the neurodegeneration characteristic of Alzheimer's diseases in rats. Noteworthy, Salvia triloba extract showed more interest in improvement Alzheimer's disease in rats.

Targeted Nano-Drug Delivery of Colchicine against Colon Cancer Cells by Means of Mesoporous Silica Nanoparticles.

Abstract: Antimitotics are important anticancer agents and include the natural alkaloid prodrug colchicine (COL). However, a major challenge of using COL as an anticancer drug is its cytotoxicity. We developed a novel drug delivery system (DDS) for COL using mesoporous silica nanoparticles (MSNs). The MSNs were functionalized with phosphonate groups, loaded with COL, and coated with folic acid chitosan-glycine complex. The resulting nanoformulation, called MSNsPCOL/CG-FA, was tested for action against cancer and normal cell lines. The anticancer effect was highly enhanced for MSNsPCOL/CG-FA compared to COL. In the case of HCT116 cells, 100% inhibition was achieved. The efficiency of MSNsPCOL/CG-FA ranked in this order: HCT116 (colon cancer) > HepG2 (liver cancer) > PC3 (prostate cancer). MSNsPCOL/CG-FA exhibited low cytotoxicity (4%) compared to COL (~60%) in BJ1 normal cells. The mechanism of action was studied in detail for HCT116 cells and found to be primarily intrinsic apoptosis caused by an enhanced antimitotic effect. Furthermore, a contribution of genetic regulation (metastasis-associated lung adenocarcinoma transcript 1 (MALAT 1), and microRNA (mir-205)) and immunotherapy effects (angiopoietin-2 (Ang-2 protein) and programmed cell death protein 1 (PD-1) was found. Therefore, this study shows enhanced anticancer effects and reduced cytotoxicity of COL with targeted delivery compared to free COL and is a novel method of developing cancer immunotherapy using a low-cost small-molecule natural prodrug.

Adaptive Control

Abstract: This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.

Immunity to Fungal Infections

Abstract: Fungal diseases represent an important paradigm in immunology, as they can result from either a lack of recognition by the immune system or overactivation of the inflammatory response. Research in this field is entering an exciting period of transition from studying the molecular and cellular bases of fungal virulence to determining the cellular and molecular mechanisms that maintain immune homeostasis with fungi. The fine line between these two research areas is central to our understanding of tissue homeostasis and its possible breakdown in fungal infections and diseases. Recent insights into immune responses to fungi suggest that functionally distinct mechanisms have evolved to achieve optimal host-fungus interactions in mammals.

Oxidative Stress in Neurodegenerative Diseases

Abstract: The pathophysiologies of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Parkinson’s disease (PD), and Alzheimer’s disease (AD), are far from being fully explained. Oxidative stress (OS) has been proposed as one factor that plays a potential role in the pathogenesis of neurodegenerative disorders. Clinical and preclinical studies indicate that neurodegenerative diseases are characterized by higher levels of OS biomarkers and by lower levels of antioxidant defense biomarkers in the brain and peripheral tissues. In this article, we review the current knowledge regarding the involvement of OS in neurodegenerative diseases, based on clinical trials and animal studies. In addition, we analyze the effects of the drug-induced modulation of oxidative balance, and we explore pharmacotherapeutic strategies for OS reduction.

Heavy Metals and Pesticides Toxicity in Agricultural Soil and Plants: Ecological Risks and Human Health Implications.

Abstract: Environmental problems have always received immense attention from scientists. Toxicants pollution is a critical environmental concern that has posed serious threats to human health and agricultural production. Heavy metals and pesticides are top of the list of environmental toxicants endangering nature. This review focuses on the toxic effect of heavy metals (cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn)) and pesticides (insecticides, herbicides, and fungicides) adversely influencing the agricultural ecosystem (plant and soil) and human health. Furthermore, heavy metals accumulation and pesticide residues in soils and plants have been discussed in detail. In addition, the characteristics of contaminated soil and plant physiological parameters have been reviewed. Moreover, human diseases caused by exposure to heavy metals and pesticides were also reported. The bioaccumulation, mechanism of action, and transmission pathways of both heavy metals and pesticides are emphasized. In addition, the bioavailability in soil and plant uptake of these contaminants has also been considered. Meanwhile, the synergistic and antagonistic interactions between heavy metals and pesticides and their combined toxic effects have been discussed. Previous relevant studies are included to cover all aspects of this review. The information in this review provides deep insights into the understanding of environmental toxicants and their hazardous effects.

A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae

Abstract: Determinations of the motion of the sun with respect to the extra-galactic nebulae have involved a K term of several hundred kilometers which appears to be variable. Explanations of this paradox have been sought in a correlation between apparent radial velocities and distances, but so far the results have not been convincing. The present paper is a re-examination of the question, based on only those nebular distances which are believed to be fairly reliable. Distances of extra-galactic nebulae depend ultimately upon the application of absolute-luminosity criteria to involved stars whose types can be recognized. These include, among others, Cepheid variables, novae, and blue stars involved in emission nebulosity. Numerical values depend upon the zero point of the period-luminosity relation among Cepheids, the other criteria merely check the order of the distances. This method is restricted to the few nebulae which are well resolved by existing instruments. A study of these nebulae, together with those in which any stars at all can be recognized, indicates the probability of an approximately uniform upper limit to the absolute luminosity of stars, in the late-type spirals and irregular nebulae at least, of the order of M (photographic) = −6.3.1 The apparent luminosities of the brightest stars in such nebulae are thus criteria which, although rough and to be applied with caution, furnish reasonable estimates of the distances of all extra-galactic systems in which even a few stars can be detected. Finally, the nebulae themselves appear to be of a definite order of absolute luminosity, exhibiting a range of four or five magnitudes about an average value M (visual) = −15.2.1 The application of this statistical average to individual cases can rarely be used to advantage, but where considerable numbers are involved, and especially in the various clusters of …