Showing papers by "Cairo University published in 2009"

On the stability of linear systems with fractional-order elements

Abstract: Linear integer-order circuits are a narrow subset of rational-order circuits which are in turn a subset of fractional-order. Here, we study the stability of circuits having one fractional element, two fractional elements of the same order or two fractional elements of different order. A general procedure for studying the stability of a system with many fractional elements is also given. It is worth noting that a fractional element is one whose impedance in the complex frequency s-domain is proportional to sα and α is a positive or negative fractional-order. Different transformations and methods will be illustrated via examples.

Correlation between the chemical structure of biodiesel and its physical properties

Abstract: Biodiesel is a renewable, biodegradable, environmentally benign, energy efficient, substitution fuel which can fulfill energy security needs without sacrificing engine’s operational performance. Thus it provides a feasible solution to the twin crises of fossil fuel depletion and environmental degradation. The properties of the various individual fatty esters that comprise biodiesel determine the overall properties of the biodiesel fuel. In turn, the properties of the various fatty esters are determined by the structural features of the fatty acid and the alcohol moieties that comprise a fatty ester. Better understanding of the structure-physical property relationships in fatty acid esters is of particular importance when choosing vegetable oils that will give the desired biodiesel quality. By having accurate knowledge of the influence of the molecular structure on the properties determined, the composition of the oils and the alcohol used can both be selected to give the optimal performance. In this paper the relationship between the chemical structure and physical properties of vegetable oil esters is reviewed and engineering fatty acid profiles to optimize biodiesel fuel characteristics is highlighted.

Nanoemulsion as a potential ophthalmic delivery system for dorzolamide hydrochloride.

Abstract: Dilutable nanoemulsions are potent drug delivery vehicles for ophthalmic use due to their numerous advantages as sustained effect and high ability of drug penetration into the deeper layers of the ocular structure and the aqueous humor. The aim of this article was to formulate the antiglaucoma drug dorzolamide hydrochloride as ocular nanoemulsion of high therapeutic efficacy and prolonged effect. Thirty-six systems consisting of different oils, surfactants, and cosurfactants were prepared and their pseudoternary-phase diagrams were constructed by water titration method. Seventeen dorzolamide hydrochloride nanoemulsions were prepared and evaluated for their physicochemical and drug release properties. These nanoemulsions showed acceptable physicochemical properties and exhibited slow drug release. Draize rabbit eye irritation test and histological examination were carried out for those preparations exhibiting superior properties and revealed that they were nonirritant. Biological evaluation of dorzolamide hydrochloride nanoemulsions on normotensive albino rabbits indicated that these products had higher therapeutic efficacy, faster onset of action, and prolonged effect relative to either drug solution or the market product. Formulation of dorzolamide hydrochloride in a nanoemulsion form offers, thus, a more intensive treatment of glaucoma, a decrease in the number of applications per day, and a better patient compliance compared to conventional eye drops.

Nipple sparing mastectomy with nipple areola intraoperative radiotherapy: one thousand and one cases of a five years experience at the European institute of oncology of Milan (EIO)

Abstract: In order to reduce mutilation, nipple-areola complex (NAC) conservation can be proposed for the treatment of breast cancer when mastectomy is indicated. To reduce the risk of retro areolar recurrence, a novel radiosurgical treatment combining subcutaneous mastectomy with intraoperative radiotherapy (ELIOT) is proposed. One thousand and one nipple sparing mastectomies (NSM) were performed from March 2002 to November 2007 at the European institute of oncology (EIO), for invasive carcinoma in 82% of the patients and in situ carcinoma in 18%. Clinical complications, aesthetic results, oncological and psychological results were recorded. A comparison was performed between the 800 patients who received ELIOT and the 201 who underwent delayed one-shot radiotherapy on the days following the operation. The median follow up time was 20 months (range 1-69) for a follow up performed in 83% of the patients. The NAC necrosed totally in 35 cases (3.5%) and partially in 55 (5.5%) and was removed in 50 (5%). Twenty infections (2%) were observed and 43 (4.3%) prostheses removed. The median rate of the patients for global cosmetic result on a scale ranging from 0 (worst) to 10 (excellent) was 8. Evaluation by the surgeon in charge of the follow-up gave a similar result. Only 15% of the patients reported a partial sensitivity of the NAC. Of the fourteen (1.4%) local recurrences, ten occurred close to the tumour site, all far from the NAC corresponding to the field of radiation. No recurrences were observed in the NAC. In a group of patients characterized by a very close free margin under the areola, no local recurrence was observed. Overall, 36 cases of metastases and 4 deaths were observed. No significant outcome difference was observed between the 800 patients receiving intraoperative radiotherapy (ELIOT) and the 201 patients receiving delayed irradiation.

On the generalization of second-order filters to the fractional-order domain

Abstract: This work is aimed at generalizing the design of continuous-time second-order filters to the non-integer-order (fractional-order) domain. In particular, we consider here the case where a filter is constructed using two fractional-order capacitors both of the same order α. A fractional-order capacitor is one whose impedance is Zc = 1/C(jω)α, C is the capacitance and α (0 < α ≤ 1) is its order. We generalize the design equations for low-pass, high-pass, band-pass, all-pass and notch filters with stability constraints considered. Several practical active filter design examples are then illustrated supported with numerical and PSpice simulations. Further, we show for the first time experimental results using the fractional capacitive probe described in Ref. 1.

Diazepam-Loaded Solid Lipid Nanoparticles: Design and Characterization

Abstract: The aim of the present study was to investigate the feasibility of the inclusion of a water-insoluble drug (diazepam, DZ) into solid lipid nanoparticles (SLNs), which offer combined advantages of rapid onset and prolonged release of the drug. This work also describes a new approach to prepare suppositories containing DZ-loaded SLN dispersions, as potential drug carrier for the rectal route. Modified high-shear homogenization and ultrasound techniques were employed to prepare SLNs. The effect of incorporation of different concentrations of Compritol® ATO 888 or Imwitor® 900K and Poloxamer 188 or Tween 80 was investigated. Results showed that varying the type or concentration of lipid matrix or surfactant had a noticeable influence on the entrapment efficiencies, particle size, and release profiles of prepared SLNs. Differential scanning calorimetry and X-ray diffraction measurements showed that the majority of SLNs possessed less ordered arrangements of crystals than the corresponding bulk lipids, which was favorable for increasing the drug loading capacity. Transmission electron microscopy and laser diffractometry studies revealed that the prepared nanoparticles were round and homogeneous and 60% of the formulations were less than 500 nm. Additionally, SLN formulations showed significant (P < 0.05) prolonged release than DZ solution. The subsequent step encompassed the preparation and evaluation of SLN-based suppositories utilizing SLN formulations that illustrated optimal release profiles. The in vitro release of DZ from the suppositories prepared using DZ-loaded SLN dispersions (equivalent to 2 mg DZ) was significantly (P < 0.05) extended compared to suppositories containing 2 mg DZ free drug.

Void Nucleation and Growth in Dual-Phase Steel 600 during Uniaxial Tensile Testing

Abstract: Commercial dual-phase (DP) steel in sheet form and comprised of ferrite, martensite, and bainite was subjected to uniaxial tension up to fracture. The damage characteristics were studied through extensive quantitative metallography and scanning electron microscope (SEM) observations of polished sections and fracture surfaces of failed specimens. The observed void nucleation mechanisms include nucleation at the martensite/ferrite interface or triple junction (most predominant), nucleation due to the cracking of martensite particles, and nucleation at the inclusions. The void characteristics in terms of area fraction, void density, void size ranges, and void orientations were analyzed as a function of thickness strain from various regions of the different uniaxial tensile test specimens taken to fracture. The damage analysis suggests that the void nucleation occurs during the entire deformation process with an almost constant rate and this rate reduces before fracture. A nucleation strain of 0.15 has been estimated for this material.

Effect of dexmedetomidine on the characteristics of bupivacaine in a caudal block in pediatrics

Abstract: Background: Dexmedetomidine (DEX) is a highly selective α2-adrenoceptor agonist that has been used increasingly in children However, the effect of caudal DEX has not been evaluated before in children This prospective randomized double-blinded study was designed to evaluate the analgesic efficacy of caudal DEX with bupivacaine in providing pain relief over a 24-h period Methods: Sixty children (ASA status I) aged 1–6 years undergoing unilateral inguinal hernia repair/orchidopexy were allocated randomly to two groups (n=30 each) Group B received a caudal injection of bupivacaine 25 mg/ml, 1 ml/kg; Group BD received the same dose of bupivacaine mixed with DEX 1 μg/kg during sevoflurane anesthesia Processed electroencephalogram (bispectral index score), heart rate, blood pressure, pulse oximetry and end-tidal sevoflurane were recorded every 5 min The characteristics of emergence, objective pain score, sedation score and quality of sleep were recorded post-operatively Duration of analgesia and requirement for additional analgesics were noted Results: The end-tidal sevoflurane concentration and the incidence of agitation were significantly lower in the BD group (P<005) The duration of analgesia was significantly longer (P<0001) and the total consumption of rescue analgesic was significantly lower in Group BD compared with Group B (P<001) There was no statistically significant difference in hemodynamics between both groups However, group BD had better quality of sleep and a prolonged duration of sedation (P<005) Conclusion: Caudal DEX seems to be a promising adjunct to provide excellent analgesia without side effects over a 24-h period It has the advantage of keeping the patients calm for a prolonged time Implications statement: Caudally administered DEX (1 μg/kg), combined with bupivacaine, was associated with an extended duration of post-operative pain relief

Amniotic membrane in ophthalmology: indications and limitations

Abstract: The amniotic membrane remains a useful tool in the treatment of several ophthalmic conditions, especially those related to the ocular surface. However, the 'success' reported in individual case reports and case series is not substantiated in the few published randomised controlled trials. More often than not, it is not as good as existing alternative options and, at best, is as good but with probably an increased cost. The variable outcomes could be related to inter and intra donor variations in the membrane and the depletion or alterations in its constituents subsequent to processing and storage. The membrane thus is a fairly 'non-standardised product' making comparisons of different applications and indications difficult. The potential for 'epidemic' infections, such as HIV, hepatitis B and C, is a serious issue as, in many parts of the world, fresh unquarantined membrane, at times with no tests for the above infectious agents, is being used. The exact mechanism of action of the membrane is not known but the consensus is that it acts as a substrate or scaffold for host cells to populate and thus facilitate healing and repair. The development of a standard 'synthetic membrane' using collagen or polymer matrices impregnated with putative beneficial ingredients, such as growth factors and antimicrobials, is being considered and may prove to be a step in the right direction.

Distinct non-target site mechanisms endow resistance to glyphosate, ACCase and ALS-inhibiting herbicides in multiple herbicide-resistant Lolium rigidum.

Abstract: This study investigates mechanisms of multiple resistance to glyphosate, acetyl-coenzyme A carboxylase (ACCase) and acetolactate synthase (ALS)-inhibiting herbicides in two Lolium rigidum populations from Australia. When treated with glyphosate, susceptible (S) plants accumulated 4- to 6-fold more shikimic acid than resistant (R) plants. The resistant plants did not have the known glyphosate resistance endowing mutation of 5-enolpyruvylshikimate-3 phosphate synthase (EPSPS) at Pro-106, nor was there over-expression of EPSPS in either of the R populations. However, [14C]-glyphosate translocation experiments showed that the R plants in both populations have altered glyphosate translocation patterns compared to the S plants. The R plants showed much less glyphosate translocation to untreated young leaves, but more to the treated leaf tip, than did the S plants. Sequencing of the carboxyl transferase domain of the plastidic ACCase gene revealed no resistance endowing amino acid substitutions in the two R populations, and the ALS in vitro inhibition assay demonstrated herbicide-sensitive ALS in the ALS R population (WALR70). By using the cytochrome P450 inhibitor malathion and amitrole with ALS and ACCase herbicides, respectively, we showed that malathion reverses chlorsulfuron resistance and amitrole reverses diclofop resistance in the R population examined. Therefore, we conclude that multiple glyphosate, ACCase and ALS herbicide resistance in the two R populations is due to the presence of distinct non-target site based resistance mechanisms for each herbicide. Glyphosate resistance is due to reduced rates of glyphosate translocation, and resistance to ACCase and ALS herbicides is likely due to enhanced herbicide metabolism involving different cytochrome P450 enzymes.

Rough Sets and Near Sets in Medical Imaging: A Review

Abstract: This paper presents a review of the current literature on rough-set- and near-set-based approaches to solving various problems in medical imaging such as medical image segmentation, object extraction, and image classification. Rough set frameworks hybridized with other computational intelligence technologies that include neural networks, particle swarm optimization, support vector machines, and fuzzy sets are also presented. In addition, a brief introduction to near sets and near images with an application to MRI images is given. Near sets offer a generalization of traditional rough set theory and a promising approach to solving the medical image correspondence problem as well as an approach to classifying perceptual objects by means of features in solving medical imaging problems. Other generalizations of rough sets such as neighborhood systems, shadowed sets, and tolerance spaces are also briefly considered in solving a variety of medical imaging problems. Challenges to be addressed and future directions of research are identified and an extensive bibliography is also included.

The effect of linolenic acid on bovine oocyte maturation and development.

Abstract: Dietary polyunsaturated fatty acids can influence reproductive performance. In dairy cattle, some high-fat diets resulted in higher blastocyst rates and improved embryo quality. These effects may partly be mediated by a direct action of fatty acids on oocyte development. The present study investigated the effect of linolenic acid (ALA; 18:3 n-3) supplementation on bovine oocyte maturation and early embryo development in vitro. Treatment of cumulus-oocyte complexes (COCs) with 50 μM ALA significantly increased the percentage of oocytes at the metaphase II (MII) stage compared with untreated controls (95% ± 2% vs. 84% ± 2%, respectively). Higher doses of ALA were detrimental. Treatment of COCs with 50 μM ALA compared with controls also resulted in a significantly higher percentage of cleaved embryos (77% ± 9% vs. 69% ± 9%, respectively) and blastocyst rate (36% ± 4% vs. 23% ± 5%, respectively) and better-quality embryos. Furthermore, COCs treated with ALA had significant increases compared with controls in:...

Phospholipid Signaling Responses in Salt-Stressed Rice Leaves

Abstract: Salinity is one of the major environmental factors limiting growth and productivity of rice plants. In this study, the effect of salt stress on phospholipid signaling responses in rice leaves was investigated. Leaf cuts were radiolabeled with 32P-orthophosphate and the lipids extracted and analyzed by thin-layer chromatography, autoradiography and phosphoimaging. Phospholipids were identified by co-migration of known standards. Results showed that 32P(i) was rapidly incorporated into the minor lipids, phosphatidylinositol bisphosphate (PIP2) and phosphatidic acid (PA) and, interestingly, also into the structural lipids phosphatidylethanolamine (PE) and phosphatidylglycerol (PG), which normally label relatively slowly, like phosphatidylcholine (PC) and phosphatidylinositol (PI). Only very small amounts of PIP2 were found. However, in response to salt stress (NaCl), PIP2 levels rapidly (<30 min) increased up to 4-fold, in a time- and dose-dependent manner. PA and its phosphorylated product, diacylglycerolpyrophosphate (DGPP), also increased upon NaCl stress, while cardiolipin (CL) levels decreased. All other phospholipid levels remained unchanged. PA signaling can be generated via the combined action of phospholipase C (PLC) and diacylglycerol kinase (DGK) or directly via phospholipase D (PLD). The latter can be measured in vivo, using a transphosphatidylation assay. Interestingly, these measurements revealed that salt stress inhibited PLD activity, indicating that the salt stress-induced PA response was not due to PLD activity. Comparison of the 32P-lipid responses in salt-tolerant and salt-sensitive cultivars revealed no significant differences. Together these results show that salt stress rapidly activates several lipid responses in rice leaves but that these responses do not explain the difference in salt tolerance between sensitive and tolerant cultivars.

Protective effects of garlic and silymarin on NDEA-induced rats hepatotoxicity.

Abstract: Background The present study was conducted to investigate the chemopreventive effects of garlic extract and silymarin on N-nitrosodiethylamine (NDEA) and carbon tetrachloride (CCl(4))-induced hepatotoxicity in male albino rats. Methods and results Animals were pretreated with garlic, silymarin or both for one week prior to the injection of NDEA. Then animals received a single injection of NDEA followed by weekly subcutaneous injections of CCl(4) for 6 weeks. Oral administration was then continued along with the injection of CCl(4) for the duration of the experiment. Serum aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), hepatic lipid peroxidation (LPO), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione-S-transferase (GST) and glutathione reductase (GSR) were measured. Injection of NDEA induced a significant elevation in serum AST, ALT and ALP. In the liver, NDEA increased oxidative stress through the increase in LPO and decrease in SOD, and GSH-dependent enzymes. Although administration of garlic or silymarin significantly reduced the liver toxicity, combined administration was more effective in preventing the development of hepatotoxicity. Conclusion These novel findings suggest that silymarin and garlic have a synergistic effect, and could be used as hepatoprotective agents against hepatotoxicity.

Efficacy and safety of deferasirox, an oral iron chelator, in heavily iron-overloaded patients with β-thalassaemia: the ESCALATOR study

Abstract: Objective: Many patients with transfusional iron overload are at risk for progressive organ dysfunction and early death and poor compliance with older chelation therapies is believed to be a major contributing factor. Phase II/III studies have shown that oral deferasirox 20–30 mg/kg/d reduces iron burden, depending on transfusional iron intake.

Atrial Fibrillation Ablation Strategies for Paroxysmal Patients: randomized comparison between different techniques.

Abstract: Background— Whether different ablation strategies affect paroxysmal atrial fibrillation (AF) long-term freedom from AF/atrial tachyarrhythmia is unclear. We sought to compare the effect of 3 different ablation approaches on the long-term success in patients with paroxysmal AF. Methods and Results— One hundred three consecutive patients with paroxysmal AF scheduled for ablation and presenting in the electrophysiology laboratory in AF were selected for this study. Patients were randomized to pulmonary vein antrum isolation (PVAI; n=35) versus biatrial ablation of the complex fractionated atrial electrograms (CFAEs; n=34) versus PVAI followed by CFAEs (n=34). Patients were given event recorders and followed up at 3, 6, 9, 12, and 15 months postablation. There was no statistical significant difference between the groups in term of sex, age, AF duration, left atrial size, and ejection fraction. At 1 year follow-up, freedom from AF/atrial tachyarrhythmia was documented in 89% of patients in the PVAI group, 91% in the PVAI plus CFAEs group, and 23% in the CFAEs group ( P <0.001) after a single procedure and with antiarrhythmic drugs. Conclusion— No difference in terms of success rate was seen between PVAI alone and PVAI associated with defragmentation. CFAEs ablation alone had the smallest impact on AF recurrences at 1-year follow-up. These results suggest that antral isolation is sufficient to treat most patients with paroxysmal AF. Received March 19, 2008; accepted February 11, 2009. # CLINICAL PERSPECTIVE {#article-title-2}