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Biomedical subjects

I S Ahmed

Publications and source records attributed to I S Ahmed.

11 recordsLinked to original sources
PubMed2006

The surfactant sensitized analytical reaction of cerium(IV) with some triphenylformazan derivatives.

Cationic surfactant, cetylpyridinium bromide (CPB), sensitizes the colour reaction of cerium(IV) with 1,3-o-hydroxyphenyl-5-phenylformazan(I), 1-m-hydroxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(II) and 1-m-carboxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(III). The formation of a soluble ternary complex of stoichiometric ratio 1:1:1 (Ce(IV)-R-CPB) is responsible for the observed enhancement in the molar absorptivity and Sandell sensitivity of the formed complex, when a surfactant is present. The ternary complex exhibits absorption maxima at 596, 571 and 607 nm (epsilon=6.05 x 10(4), 6.28 x 10(4) and 8.06 x 10(4)L mol(-1)cm(-1)) using triphenylformazan derivatives I, II and III, respectively. Beer's law is obeyed between 0.15 and 2.5 microg ml(-1), whereas, optimum concentration range applying Ringbom method is in the range 0.30-2.25 microg ml(-1). Conditional formation constants in the presence and absence of CPB for Ce(IV) complexes have been calculated. The proposed method has been successfully applied to the analysis of magnesium-base cerium alloys and synthetic mixtures corresponding to various cerium alloys.

Alloys↗
PubMed2006

Formulation of a fast-dissolving ketoprofen tablet using freeze-drying in blisters technique.

The aim of this work was to develop a ketoprofen tablet which dissolve-rapidly in the mouth, therefore, needing not be swallowed. The solubility and dissolution rate of poorly water-soluble ketoprofen was improved by preparing a lyophilized tablet (LT) of ketoprofen using freeze-drying technique. The LT was prepared by dispersing the drug in an aqueous solution of highly water-soluble carrier materials consisting of gelatin, glycine, and sorbitol. The mixture was dosed into the pockets of blister packs and then was subjected to freezing and lyophilization. The saturation solubility and dissolution characteristics of ketoprofen from the LT were investigated and compared to the plain drug and the physical mixture (PM). Results obtained showed that the increase in solubility of ketoprofen from LT matrix, nearly three times greater than the solubility of the plain drug, was due to supersaturation generated by amorphous form of the drug. Results obtained from dissolution studies showed that LT of ketoprofen significantly improved the dissolution rate of the drug compared with the PM and the plain drug. More than 95% of ketoprofen in LT dissolved within 5 min compared to only 45% of ketoprofen plain drug dissolved during 60 min. Initial dissolution rate of ketoprofen in LT was almost tenfold higher than that of ketoprofen powder alone. Crystalline state evaluation of ketoprofen in LT was conducted through differential scanning calorimetry (DCS) and x-ray powder diffraction (XRPD) to denote eventual transformation to amorphous state during the process. Scanning electron microscopic (SEM) analysis was performed and results suggest reduction in ketoprofen particle size.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Effect of simulated gastrointestinal conditions on drug release from pectin/ethylcellulose as film coating for drug delivery to the colon.

The aim of this work was to investigate the effect of acidic pH representative of gastric fluid on the release of 5-aminosalicylic acid from beads coated with pectin/ethylcellulose as film coating intended for drug delivery to the colon, in media mimicking the lower gastrointestinal (GI) tract and representative of colonic conditions. In this work, the in vitro incubation of the beads in acid medium was found to influence the hydration and the swelling characteristics of pectin after transfer into simulated intestinal fluid and simulated cecal fluid containing pectinolytic enzymes. Moreover, the drug release profiles from the beads in simulated intestinal fluid after incubation for 2 h or 30 min in simulated gastric fluid vs. no acid incubation were found to be very different. The in vitro degradation of pectin in the coat by pectinolytic enzymes in simulated cecal fluid depended on whether the beads were placed in simulated gastric fluid prior to testing in simulated intestinal fluid. The percentage drug release also depended on the ratio of pectin to ethylcellulose in the coat.

Animals↗
PubMed2003

Utility of oxidation-reduction reaction for the determination of ranitidine hydrochloride in pure form, in dosage forms and in the presence of its oxidative degradates.

Three simple, accurate and sensitive colorimetric methods (A, B and C) for the determination of ranitidine HCl (RHCl) in bulk sample, in dosage forms and in the presence of its oxidative degradates are described. The first method A is based on the oxidation of the drug by N-bromosuccinimide (NBS) and determination of the unreacted NBS by measurement of the decrease in absorbance of amaranth dye (AM) at a suitable lambda(max)=520 nm. The methods B and C involve the addition of excess Ce(4+) and determination of the unreacted oxidant by decrease the red color of chromotrope 2R (C2R) at a suitable lambda(max)=528 nm for method B or decrease the orange pink color of rhodamine 6G (Rh6G) at a suitable lambda(max)=526 nm for method C. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 0.2-3.6, 0.1-2.8 and 0.1-2.6 microg ml(-1) for methods A, B and C, respectively. The apparent molar absorptivity. Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.3-3.4, 0.2-2.6 and 0.2-2.4 microg ml(-1) for methods A, B and C, respectively. Analyzing pure and dosage forms containing RHCl tested the validity of the proposed methods. The relative standard deviations were </=1.38 with recoveries 98.9-101.0%.

Bromides↗
PubMed2002

Spectral studies and molecular orbital PPP-calculations of some azo-dyes.

The UV, IR and 1H-NMR spectra of some 4-(R-phenyl azo) 1-hydroxy 2-naphthoic acid derivatives are studied. The effects of substituent groups and the solvent polarity on electronic spectral, IR bands and 1H-NMR proton chemical shifts are considered, the molecular orbital calculations obtained are rationalized quantitatively with that obtained practically using the PPP-model with configuration interaction (CI).

Azo Compounds↗
PubMed2001

G-protein-coupled receptor stimulation of the p42/p44 mitogen-activated protein kinase pathway is attenuated by lipid phosphate phosphatases 1, 1a, and 2 in human embryonic kidney 293 cells.

Sphingosine 1-phosphate, lysophosphatidic acid, and phosphatidic acid bind to G-protein-coupled receptors to stimulate intracellular signaling in mammalian cells. Lipid phosphate phosphatases (1, 1a, 2, and 3) are a group of enzymes that catalyze de-phosphorylation of these lipid agonists. It has been proposed that the lipid phosphate phosphatases exhibit ecto activity that may function to limit bioavailability of these lipid agonists at their receptors. In this study, we show that the stimulation of the p42/p44 mitogen-activated protein kinase pathway by sphingosine 1-phosphate, lysophosphatidic acid, and phosphatidic acid, all of which bind to G(i/o)-coupled receptors, is substantially reduced in human embyronic kidney 293 cells transfected with lipid phosphate phosphatases 1, 1a, and 2 but not 3. This was correlated with reduced basal intracellular phosphatidic acid and not ecto lipid phosphate phosphatase activity. These findings were supported by results showing that lipid phosphate phosphatases 1, 1a, and 2 also abrogate the stimulation of p42/p44 mitogen-activated protein kinase by thrombin, a peptide G(i/o)-coupled receptor agonist whose bioavailability at its receptor is not subject to regulation by the phosphatases. Furthermore, the lipid phosphate phosphatases have no effect on the stimulation of p42/p44 mitogen-activated protein kinase by other agents that do not use G-proteins to signal, such as serum factors and phorbol ester. Therefore, these findings show that the lipid phosphate phosphatases 1, 1a, and 2 may function to perturb G-protein-coupled receptor signaling per se rather than limiting bioavailability of lipid agonists at their respective receptors.

Cell Line↗
PubMed1999

Shear-induced tyrosine phosphorylation in endothelial cells requires Rac1-dependent production of ROS.

The shear-induced intracellular signal transduction pathway in vascular endothelial cells involves tyrosine phosphorylation and activation of mitogen-activated protein (MAP) kinase, which may be responsible for the sustained release of nitric oxide. MAP kinase is known to be activated by reactive oxygen species (ROS), such as H2O2, in several cell types. ROS production in ligand-stimulated nonphagocytic cells appears to require the participation of a Ras-related small GTP-binding protein, Rac1. We hypothesized that Rac1 might serve as a mediator for the effect of shear stress on MAP kinase activation. Exposure of bovine aortic endothelial cells to laminar shear stress of 20 dyn/cm2 for 5-30 min stimulated total cellular and cytosolic tyrosine phosphorylation as well as tyrosine phosphorylation of MAP kinase. Treating endothelial cells with the antioxidants N-acetylcysteine and pyrrolidine dithiocarbamate inhibited in a dose-dependent manner the shear-stimulated increase in total cytosolic and, specifically, MAP kinase tyrosine phosphorylation. Hence, the onset of shear stress caused an enhanced generation of intracellular ROS, as evidenced by an oxidized protein detection kit, which were required for the shear-induced total cellular and MAP kinase tyrosine phosphorylation. Total cellular and MAP kinase tyrosine phosphorylation was completely blocked in sheared bovine aortic endothelial cells expressing a dominant negative Rac1 gene product (N17rac1). We concluded that the GTPase Rac1 mediates the shear-induced tyrosine phosphorylation of MAP kinase via regulation of the flow-dependent redox changes in endothelial cells in physiological and pathological circumstances.

Animals↗
PubMed1995

The binding of jacalin with rabbit immunoglobulin G.

Rabbit immunoglobulin G (IgG) was subjected to affinity chromatography on a column of jacalin-Sepharose 4B. While the majority of IgG molecules did not bind, a small fraction, representing about 25% of the total IgG applied, bound to jacalin-Sepharose 4B. The binding of rabbit IgG to jacalin was further evidenced by ELISA performed on jacalin coated microtitre plates. While the jacalin-retained IgG fraction displayed strong binding, the unretained fraction did not demonstrate any detectable binding. Upon SDS-PAGE, both the jacalin retained and unretained rabbit IgG fractions displayed identical protein profiles. Upon protein blotting it was demonstrated that jacalin binding sites were located only on the heavy chain of IgG. These results suggest that rabbit IgG molecules are heterogeneous with respect to their glycosylation patterns. A small fraction of rabbit IgG molecules binds jacalin and the process is probably mediated through O-linked oligosaccharides present on the heavy chain of IgG.

Animals↗
PubMed1994

Knowledge, attitudes and practices of mothers regarding diarrhoea among children in a Sudanese rural community.

A survey of knowledge, attitudes and practices of mothers in the rural communities of two villages in Sudan regarding diarrhoeal diseases in children was conducted using a focus group research technique. Seven groups of literate mothers (87 mothers) and 13 groups of illiterate mothers (152 mothers) interviewed comprised 85% of mothers with children under 5 years of age in that community. The study showed that mothers can define and describe diarrhoea, however awareness about the aetiology and the importance of germs in its causation was low. The majority of mothers attributed diarrhoea to teething, milk of pregnant women, hot food and salty water. Less than 40% of mothers identify symptoms and signs of "dehydration" and the need for consultation. Only 10% could relate danger signs to severe dehydration. The ORS use rate was very low (2.1-4.3%). Although awareness about ORS was high (100%), only 25% prepared and used it correctly. However, home made fluids including rice water, custard, pap and tabaladi juice were used by 45% of the mothers. 45% of illiterate mothers stop breast feeding and food during diarrhoea compared to 30% of literate mothers. Harmful practices used in caring for children with diarrhoea included: fumigation (50%), cauterization and removal of teeth buds (45% illiterate mothers, 10% literate), withholding of breast feeding and indiscriminate use of drugs and herbs in 30%.

Breast Feeding↗
PubMed1987

Cibenzoline-induced hypoglycemia.

Antiarrhythmic-induced hypoglycemia is an ill-defined phenomenon. Sporadic cases have been reported with disopyramide, a class IA antiarrhythmic agent. We report a case of cibenzoline-induced hypoglycemia in an elderly male with a history of ischemic heart disease, congestive heart failure, ventricular arrhythmias, and chronic obstructive pulmonary disease. Cibenzoline is a class I antiarrhythmic agent currently undergoing clinical investigation in the U.S. The initial hypoglycemic episode occurred after two years of successful treatment with cibenzoline. Blood glucose during the first hypoglycemic episode was 40 mg/dL. The hypoglycemia was associated with central nervous system depression, hyperkalemia, electrocardiographic abnormalities, and respiratory distress. Rechallenge with cibenzoline resulted in recurrence of symptoms and a blood glucose level of 21 mg/dL. A second rechallenge resulted in symptoms suggestive of hypoglycemia, but cibenzoline was discontinued before frank hypoglycemia and hyperkalemia recurred. Hypoglycemia occurred during periods of fasting, which most likely ruled out reactive-type hypoglycemia. Insulinoma was ruled out by the presence of normal fasting blood glucose and plasma insulin levels. It was concluded that this patient's hypoglycemia was secondary to cibenzoline. Hypoglycemia is a rare and sporadic adverse effect associated with antiarrhythmic therapy. However, the severity of these reactions warrants increased awareness of their occurrence in patients presenting with symptoms of hypoglycemia who are receiving disopyramide or cibenzoline.

Aged↗