Ahmed Galal

Simultaneous determination of catecholamines, uric acid and ascorbic acid at physiological levels using poly(N-methylpyrrole)/Pd-nanoclusters sensor

An interesting electrochemical sensor has been constructed by the electrodeposition of palladium nanoclusters (Pd(nano)) on poly(N-methylpyrrole) (PMPy) film-coated platinum (Pt) electrode. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy were used to characterize the properties of the modified electrode. It was demonstrated that the electroactivity of the modified electrode depends strongly on the electrosynthesis conditions of the PMPy film and Pd(nano). Moreover, the modified electrode exhibits strong electrocatalytic activity toward the oxidation of a mixture of dopamine (DA), ascorbic acid (AA), and uric acid (UA) with obvious reduction of overpotentials. The simultaneous analysis of this mixture at conventional (Pt, gold [Au], and glassy carbon) electrodes usually struggles. However, three well-resolved oxidation peaks for AA, DA, and UA with large peak separations allow this modified electrode to individually or simultaneously analyze AA, DA, and UA by using differential pulse voltammetry (DPV) with good stability, sensitivity, and selectivity. This sensor is also ideal for the simultaneous analysis of AA, UA and either of epinephrine (E), norepinephrine (NE) or l-DOPA. Additionally, the sensor shows strong electrocatalytic activity towards acetaminophen (ACOP) and other organic compounds. The calibration curves for AA, DA, and UA were obtained in the ranges of 0.05 to 1mM, 0.1 to 10 microM, and 0.5 to 20 microM, respectively. The detection limits (signal/noise [S/N]=3) were 7 microM, 12 nM, and 27 nM for AA, DA, and UA, respectively. The practical application of the modified electrode was demonstrated by measuring the concentrations of AA, DA, and UA in injection sample, human serum, and human urine samples, respectively, with satisfactory results. The reliability and stability of the modified electrode gave a good possibility for applying the technique to routine analysis of AA, DA, and UA in clinical tests.

Near vision restoration with refractive lens exchange and pseudoaccommodating and multifocal refractive and diffractive intraocular lenses: Comparative clinical study

Purpose: To evaluate near visual performance after implantation of a pseudoaccommodating intraocular lens (IOL) (Crystalens® AT‐45, eyeonics) or a multifocal IOL (refractive model, AMO Array®; diffractive model, AcriTec TwinSet) after lens surgery. Settings: Instituto Oftalmológico de Alicante, Miguel Hernandez University, Alicante, Spain. Methods: Forty patients were included in this prospective clinical comparative study. The patients were divided into 3 groups according to the type of IOL implanted. Group 1 included 24 eyes (12 patients) implanted with the Crystalens IOL; Group 2, 32 eyes (16 patients) with the Array IOL, and Group 3, 24 eyes (12 patients) with the TwinSet IOL. Bilateral phacoemulsification and IOL implantation were performed in all patients, and the follow‐up was 1 year. The postoperative main visual outcome evaluations were uncorrected and best corrected distance and near visual acuities, mean add for near, and best distance‐corrected near acuity. Results: In Group 1, the mean uncorrected near acuity was 20/40 preoperatively and 20/25 after 1 year. The mean preoperative best distance‐corrected near acuity was 20/32 and 20/25 after 1 year. In Group 2, the mean uncorrected near acuity was 20/40 and 20/25, respectively. The mean preoperative best distance‐corrected near acuity was 20/32 and 20/25 after 1 year. In Group 3, the mean uncorrected near acuity was 20/63 preoperatively; after 1 year, it was approximately 20/25. The mean best distance‐corrected near acuity was 20/50 and 20/25, respectively. A neodymium:YAG laser capsulotomy was performed for posterior capsule opacification when required, with no change in the refractive outcome. Conclusions: Implantation of multifocal and pseudoaccommodating IOLs provides adequate near vision restoration. The TwinSet IOL provided faster recovery of near vision than the other 2 IOLs. The Crystalens IOL provided less postoperative visual phenomena with favorable near vision. The Array IOL achieved the most comfortable distance and near vision.

One or 2 Intacs segments for the correction of keratoconus.

Purpose: To evaluate the effect of implanting 1 or 2 intracorneal rings (Intacs, KeraVision) as a device to correct, stabilize, and/or improve the best corrected visual acuity in patients with clear cornea keratoconus oriented by the preoperative corneal topography pattern. Setting: Vissum/Instituto Oftalmológico de Alicante, Miguel Hernandez University, Alicante, Spain. Methods: In this prospective comparative consecutive study, Intacs segments were implanted in 26 keratoconic eyes with clear central corneas of 19 consecutive patients (9 women and 10 men). Corneas were divided into 2 groups according to the topographic pattern of the cone. Group I included keratoconus not crossing the 180° meridian and Group II included keratoconus crossing the 180° meridian. The Intacs were horizontally placed through a lateral clear corneal incision. According to the corneal topography 1 segment was implanted 0.45 mm inferior in Group I, and 2 segments were implanted, 1 0.25 mm superior and the other 0.45 mm inferior, in Group II. All cases completed a minimum follow‐up of 1 year. Differences between preoperative and postoperative uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity (BSCVA), manifest refraction, and keratometry were clinically and statistically evaluated. Results: Spherical equivalent error and refractive astigmatism were significantly reduced. The mean keratometric values were reduced following Intacs insertion in both groups. At the end of the first year of the postoperative follow‐up, Group I (1 segment) had an improvement in mean UCVA to 20/50 (0.4 ± 0.22 decimal value), which was statistically significant when compared to the preoperative UCVA of 20/100 (0.2 ± 0.13 decimal value) (P = .011). Mean BSCVA was 20/32 (0.62 ± 0.24 decimal value), which was also statistically significant when compared to the preoperative BSCVA, which was 20/50 (0.4 ± 0.21 decimal value) (P = .002). In Group II (2 segments), UCVA after 1 year was 20/63 (0.34 ± 0.17 decimal value), which was statistically significant when compared to the preoperative UCVA of 20/400 (0.06 ± 0.02 decimal value) (P = .001). Mean BSCVA was 20/32 (0.62 ± 0.27 decimal value), which was significantly better than the preoperative UCVA of 20/50 (0.38 ± 0.22 decimal value) (P = .001). In 4 eyes, the inferior segment was removed because of partial extrusion during the postoperative follow‐up. Conclusions: Treatment of keratoconus with 1 or 2 Intacs segments oriented by the preoperative corneal topography used in this study proved to be effective in decreasing the corneal steepening and astigmatism and improving BSCVA. Further follow‐up is needed to determine the final effect of Intacs on the progression of the corneal disease.

Pharmacological Studies of Rhus Retinorrhaea

AbstractAn ethanol extract of Rhus retinorrhaea Steud. ex. A. Rich-has been studied for anti-inflammatory, antipyretic, and analgesic activities in experimental models. The extract produced significant inhibition of carrageenan-induced paw edema, an insignificant cotton pellet granuloma in rats, a significant dose-dependent reduction of yeast-induced hyperpyrexia, and inhibition of acetic acid-induced writhing in mice. Other pharmacological studies revealed central nervous system depressing and negative inotropic and chronotropic activities. The acute toxicity studies showed no mortality and adverse effects up to a 3g/kg dose in mice.

Poly(3,4-ethylene-dioxythiophene) electrode for the selective determination of dopamine in presence of sodium dodecyl sulfate

A novel biosensor using poly(3,4-ethylene dioxythiophene) (PEDOT) modified Pt electrode was developed for selective determination of dopamine (DA) in presence of high concentrations of ascorbic acid (AA) and uric acid (UA) with a maximum molar ratio of 1/1000, and 1/100 in the presence of sodium dodecyl sulfate (SDS). SDS forms a monolayer on PEDOT surface with a high density of negatively charged end directed outside the electrode. The electrochemical response of dopamine was improved by SDS due to the enhanced accumulation of protonated dopamine via electrostatic interactions. The common overlapped oxidation peaks of AA, UA and DA can be resolved by using SDS as the DA current signal increases while the corresponding signals for AA and UA are quenched. The use of SDS in the electrochemical determination of dopamine using linear sweep voltammetry at modified electrode PEDOT/Pt resulted in detecting dopamine at relatively lower concentrations. The DA concentration could be measured in the linear range of 0.5 to 25μmol L(-1) and 30μmol L(-1) to 0.1mmol L(-1) with correlation coefficients of 0.998 and 0.993 and detection limits 61nmol L(-1) and 86nmol L(-1), respectively. The validity of using this method in the determination of dopamine in human urine was also demonstrated.

THE ELECTROCHEMISTRY OF NEUROTRANSMITTERS AT CONDUCTING ORGANIC POLYMER ELECTRODES : ELECTROCATALYSIS AND ANALYTICAL APPLICATIONS

The electrooxidation of catechols, catecholamines and NADH at conventional electrode materials is generally characterized by high degrees of irreversibility as well as strong adsorption and, hence, fouling by reactants and/or products of the reactions. On the contrary, the rates of the electron transfer are highly catalysed by the use of conducting polymer films, such as poly(3-methylthiophene), polyphenylene, polyanaline and polypyrrole, as described here. Furthermore, the usual fouling problems are eliminated. Even interference from electroinactive large proteins, such as haemoglobin, and other surfactants are substantially reduced. Also, electron spectroscopy for chemical analysis, energy-dispersive analysis of X-rays, theoretical diffusion coefficient calculations, metal ion coordination, solution diffusion analyses of cyclic voltammograms etc. show that the electron transfer occurs at the polymer-solution interface and not at the inert electrode substrate surface after diffusion through the polymer matrix or through pores. The analytical application of these polymer electrodes as amperometric detectors for flow injection analysis and high performance liquid chromatography are given. In addition, selective potentiometric electrodes for catecholamines based on conducting polymer films of crown ethers, such as binaphthyl-20-crown-6, dibenzo-18-crown-6, etc., have been developed and characterized. These potentiometric detectors significantly decrease the usual interferences of ascorbic acid, uric acid and acetaminophen found in amperometric detection.

Retinal image quality after microincision intraocular lens implantation

PURPOSE: To evaluate the modulation‐transfer function (MTF) in eyes implanted with a conventional intraocular lens (IOL) and 2 IOLs designed for microincision cataract surgery (MICS). SETTING: Research, Development, and Innovation Department, Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: This prospective nonrandomized consecutive series comprised 30 eyes implanted with 1 of the following IOLs: conventional acrylic foldable (AcrySof MA60BM, Alcon Laboratories) or the UltraChoice 1.0 ThinOptX (ThinOptX Inc.) or the Acri.Smart 48S (Acri.Tech) MICS IOL. The 0.5 MTF and 0.1 MTF following MICS were calculated 3 months after implantation with the Optical Quality Analysis System (OQAS) for a 5 mm pupil. The differences were statistically analyzed with the Mann‐Whitney U test. RESULTS: The values of 0.5 MTF for AcrySof, UltraChoice, ThinOptX, and Acri.Smart IOLs were, respectively, 2.647 cycles per degree (cpd) ± 0.833 (SD), 2.601 ± 0.986 cpd, and 3.453 ± 0.778 cpd. The mean 0.1 MTF values for the same IOLs were 8.720 ± 3.074 cpd, 8.814 ± 4.380 cpd, and 11.418 ± 2.574 cpd, respectively. Statistical analysis did not show significant differences in 0.5 MTF and 0.1 MTF between the conventional IOL and MICS IOLs. CONCLUSIONS: Microincision cataract surgery IOLs showed excellent MTF performance when implanted after cataract surgery, equal to that of conventional IOLs. An in vivo MTF study may be an excellent option to evaluate IOL performance in the eye.

Artemisinin dimer anticancer activity correlates with heme-catalyzed reactive oxygen species generation and endoplasmic reticulum stress induction.

Analogs of the malaria therapeutic, artemisinin, possess in vitro and in vivo anticancer activity. In this study, two dimeric artemisinins (NSC724910 and 735847) were studied to determine their mechanism of action. Dimers were >1,000 fold more active than monomer and treatment was associated with increased reactive oxygen species (ROS) and apoptosis induction. Dimer activity was inhibited by the antioxidant L‐NAC, the iron chelator desferroxamine and exogenous hemin. Similarly, induction of heme oxygenase (HMOX) with CoPPIX inhibited activity, whereas inhibition of HMOX with SnPPIX enhanced it. These results emphasize the importance of iron, heme and ROS in activity. Microarray analysis of dimer treated cells identified DNA damage, iron/heme and cysteine/methionine metabolism, antioxidant response, and endoplasmic reticulum (ER) stress as affected pathways. Detection of an ER‐stress response was relevant because in malaria, artemisinin inhibits pfATP6, the plasmodium orthologue of mammalian sarcoplasmic/endoplasmic reticulum Ca2+‐ATPases (SERCA). A comparative study of NSC735847 with thapsigargin, a specific SERCA inhibitor and ER‐stress inducer showed similar behavior in terms of transcriptomic changes, induction of endogenous SERCA and ER calcium mobilization. However, thapsigargin had little effect on ROS production, modulated different ER‐stress proteins and had greater potency against purified SERCA1. Furthermore, an inactive derivative of NSC735847 that lacked the endoperoxide had identical inhibitory activity against purified SERCA1, suggesting that direct inhibition of SERCA has little inference on overall cytotoxicity. In summary, these data implicate indirect ER‐stress induction as a central mechanism of artemisinin dimer activity.

Effect of surfactants on the voltammetric response and determination of an antihypertensive drug

The effect of adding surface-active agents to electrolytes containing terazosin, an antihypertensive drug, on the voltammetric response of glassy carbon electrode was studied. The current signal due to the oxidation process was a function of the amount of terazosin, pH of the medium, type of surfactant, and accumulation time at the electrode surface. Two surfactants were used, an anionic type, sodium dodecyl sulfate (SDS) and a cationic type, cetyl trimethyl ammonium bromide (CTAB). Addition of SDS to the terazosin-containing electrolyte was found to enhance the oxidation current signal while CTAB showed an opposite effect. Beside the interfacial interaction of the surfactant with the electrode surface in reference to the bias applied potential and the charge of surfactant, terazosin-surfactant interaction in the electrolytic solution was found to be critical to the magnitude of current signal. Addition of SDS to terazosin-containing buffer solution resulted in a decrease in the drug absorption spectrum both in the ultra-violet and visible (UV-vis) regions. Moreover, NMR measurements showed considerable chemical shifts for the aromatic protons of the quinazolinyl moiety of the terazosin in presence of SDS. The affected aromatic protons are positioned next to the interacting protonated amino-group of the terazosin with the charged sulfonate-group of SDS. On the other hand, addition of CTAB did not cause noticeable changes both to the UV-vis and NMR spectra of the drug. The use of SDS in the electrochemical determination of terazosin using linear sweep voltammetry and differential pulse voltammetry at solid glassy carbon electrode enhanced the detection limit from 6.00x10(-7)molL(-1) in absence of surfactant to 4.58x10(-9)molL(-1) when present. The validity of using this method in the determination of drug active ingredient in urine samples and tablet formulations was also demonstrated.

Visual outcome of microincision cataract surgery with implantation of an Acri. Smart lens.

PURPOSE: To evaluate visual and refractive outcome of microincision cataract surgery (MICS) with implantation of an Acri.Smart 48S intraocular lens (IOL) (Acri.Tech) through a sub‐1.9 mm incision. SETTING: Vissum/Instituto Oftalmologico de Alicante and Ophthalmology Department, Miguel Hernandez University, Alicante, Spain. METHODS: In this consecutive prospective observational noncomparative clinical trial, 45 eyes were included. Microincision cataract surgery was performed through a 1.9 mm or smaller clear corneal incision using low ultrasound power MICS. The IOL was injected using a hydraulic cartridge and injector. The final size of the clear corneal incision, postoperative uncorrected and best corrected near and distance acuities, lens stability, ease of implantation, rate of posterior capsule opacification (PCO), and complications were reported up to 6 months. RESULTS: The Acri.Smart lens was inserted through mean incision of 1.5 mm ± 0.3 (SD). The mean uncorrected distance visual acuity improved significantly from 20/100 (0.2 ± 0.2 decimal value) preoperatively to 20/32 (0.7 ± 0.3) by the end of 6 months postoperatively (P<.000). The best corrected distance visual acuity improved significantly from 20/50 (0.4 ± 0.2) preoperatively to 20/25 (0.9 ± 0.2) after 6 months (P<0.000). The uncorrected near visual acuity at the end of 6 months was 20/32 (0.6 ± 0.2, P<.000). The mean postoperative spherical equivalent was −1.1 ± 0.9 diopters (P<.947). The safety index was 2.5 for distance and 1.4 for near. There were no intraoperative or postoperative complications. No eye had a neodymium:YAG laser capsulotomy for PCO or reported undesirable complications at the end of 6 months. CONCLUSIONS: Results show that the Acri.Smart 48S IOL is a safe, effective, and stable lens that could be inserted through sub‐1.9 mm incisions. It provided excellent surgical performance, predictability, and some degree of pseudoaccommodation.