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Biomedical subjects

S Mustafa

Publications and source records attributed to S Mustafa.

At least 19 recordsLinked to original sources
PubMed2006

Altered intravenous pharmacokinetics of topotecan in rats with acute renal failure (ARF) induced by uranyl nitrate: do adenosine A1 antagonists (selective/non-selective) normalize the altered topotecan kinetics in ARF?

A series of exploratory investigations with multiple agents was carried out in normal rats and in rats with uranyl nitrate-induced acute renal failure to understand the disposition characteristics of intravenous topotecan (TPT) used as a model substrate. The disposition of TPT was unaltered in normal rats when treated with methotrexate, whereas treatment with probenecid increased the systemic exposure of TPT. In case of uranyl nitrate-induced acute renal failure (UN-ARF) rats, the systemic exposure of TPT was increased when compared with normal rats, whereas in UN-ARF rats treated with probenecid a further reduction in renal clearance of TPT was noted as compared with that of UN-ARF induced rats. Thus, TPT may be involved in the tubular secretory pathway when a passive glomerular filtration pathway for elimination was not possible. The disposition of TPT did not normalize in UN-ARF rats when treated with caffeine, a non-selective adenosine A1 receptor antagonist, whereas the selective adenosine A1 receptor antagonist (1,3-dipropyl-8-phenylxanthine, DPPX) normalized TPT pharmacokinetic disposition by improving renal function. Renal excretion studies demonstrated that CLR improved by almost fivefold following DPPX treatment in ARF rats. In addition, the qualitative stability/metabolism pattern of TPT in liver microsomes prepared from various groups of rats (normal rats, UN-ARF rats, rats treated with DPPX, and UN-ARF rats treated with DPPX) was found to be similar. In summary, using a pharmacokinetic tool as a surrogate, it has been shown that the pharmacokinetic disposition of TPT improved considerably upon treatment with DPPX, a selective adenosine A1 antagonist.

Acute Kidney Injury↗
PubMed2006

Polymorphism in the tissue factor region is associated with basal but not endotoxin-induced tissue factor-mRNA levels in leukocytes.

OBJECTIVE: Tissue factor (TF) plays a central role during disseminated intravascular coagulation (DIC) in sepsis. We hypothesized that a frequent D/I polymorphism, at nucleotide position -1208 in the promoter region, could influence TF-mRNA and downstream coagulation. METHODS: Basal- and lipopolysaccharide (LPS)-induced TF-mRNA expression, microparticle-associated TF-procoagulant activity and coagulation were determined in healthy men (n = 74) before and after endotoxin (LPS) infusion (2 ng kg(-1)). Basal values of TF-mRNA ranged between 34 and > 37.5 cycles. RESULTS: Baseline TF-mRNA levels significantly differed between genotypes: I/I carriers had almost 2-fold higher TF-mRNA levels compared to D/D carriers at baseline (P < 0.01). In accordance, higher levels of microparticle-associated TF-procoagulant activity could be seen in I/I carriers. However, the genotype did not affect basal or LPS-induced levels of prothrombin fragment F1+2, D-dimer or cytokines including tumor necrosis factor and interleukin-6. CONCLUSION: The TF-1208 polymorphism is functional in that it regulates basal TF-mRNA in circulating monocytes and circulating microparticle-associated TF-procoagulant activity in vivo, but does not influence the relative increase in TF-mRNA or coagulation activation during low-grade endotoxemia.

Disseminated Intravascular Coagulation↗
PubMed2005

Sorption of divalent metal ions on CrPO4.

The divalent metal ion sorption (Cu(2+), Cd(2+), Ni(2+), and Pb(2+)) on chromium phosphate (CrPO(4)) was studied as a function of pH, temperature, and concentration of metal ions. The sorption of metal ions is observed to increase with the increase in pH, temperature, and concentration of metal ions in solution. The mechanism of sorption is found to be the exchange of the hydrolyzed metal cations with the protons from solid at high temperature. The sorption at low temperature is found to be accompanied by the precipitation of the corresponding metal phosphates such as Pb(3)(PO(4))(2).

Adsorption↗
PubMed2005

Ion exchange sorption of Pb2+ ions on CrPO4.

The chromium(III) phosphate was observed to have a high affinity towards Pb2+ ion and the sorption capacities were found to be in the order: Pb2+ > Cu2+ > Cd2+ > Ni2+. Different characterization methods i.e. FTIR, SEM and EDX were employed to investigate the sorption mechanism of Pb2+ by chromium(III) phosphate, which showed that no new solid phases were present in the residue after sorption of Pb2+. The exchange between protons from the surface and Pb2+ from solutions was found to be responsible for Pb2+ sorption by chromium (III) phosphate.

Adsorption↗
PubMed2005

Cooling-induced contraction of the rat gastric fundus: mediation via transient receptor potential (TRP) cation channel TRPM8 receptor and Rho-kinase activation.

1. Cooling has been shown to induce contractions of several smooth muscles in vitro. However, the mechanism involved in the response is not yet known. In the present study, we investigated the possible involvement of transient receptor potential (TRP) cation channel TRPM8 receptors and the Rho-kinase pathway in cooling-induced contraction of the rat fundus. 2. Cooling-induced contractions were inversely proportional to temperature. Contractions were significantly reduced (by 65.6 +/- 2.4%; P < 0.05) in a Ca2+-free (1 mmol/L EGTA) medium, but were not significantly inhibited by nifedipine (10(-6) mol/L). 3. Capsazepine (3 x 10(-6) and 3 x 10(-5) mol/L), a TRPM8 receptor antagonist, inhibited cooling-induced contraction of the rat gastric fundus. 4. The Rho-kinase inhibitor Y-27632 concentration-dependently inhibited cooling-induced contraction of the gastric fundus, producing approximately 90% inhibition at a concentration of 10(-5) mol/L. Contractions were also inhibited by genistein (3 x 10(-5) mol/L), a tyrosine kinase inhibitor, but not by GF 109203X (10(-7) mol/L), a protein kinase C inhibitor. 5. Using reverse transcription-polymerase chain reaction techniques, it was observed that the mRNA for the TRPM8 receptor and Rho-kinase were expressed in the rat gastric fundus. 6. These results would suggest that cooling-induced contraction of the rat fundus is mediated by activation of TRPM8 receptors via a mechanism involving activation of Rho-kinase.

Amides↗
PubMed2005

Elevated serum alanine aminotransferase (ALT) levels in patients with serologically verified Mycoplasma pneumoniae pneumonia.

The possibility of liver involvement in Mycoplasma pneumoniae pneumonia is still controversial. This study investigated 33 adult patients with serologically confirmed M. pneumoniae community-acquired pneumonia (CAP) (median age 31 years) and 38 patients with bacteraemic Streptococcus pneumoniae CAP (median age 54 years), all without pre-existing liver disease. Serum alanine aminotransferase (ALT) levels were elevated in 12 (36.4%) patients with M. pneumoniae CAP (median 53.5 U/L), and in four (10.5%) patients with S. pneumoniae CAP (median 61 U/L) (p 0.025). In most patients with M. pneumoniae CAP, the elevated ALT levels decreased during macrolide therapy, although this decrease was not significant.

Adolescent↗
PubMed2004

Temperature effect on xanthate sorption by chalcopyrite.

Xanthate ions sorption on copper ore (chalcopyrite) is studied as a function of temperature (273-293 K) in the pH range (8-11). The sorption of xanthate ions at all the pH values is observed to increase with the increase in temperature. The changes in pH, dissolution studies of the ore, SO2(4)- concentration determinations, and FTIR studies were employed to probe the mechanism of the process of adsorption. The results are found to fit successfully to the linear form of the Freundlich equation. The isosteric heats of adsorption (DeltaHi) are also calculated and show that the adsorption of xanthate on copper ore under the given experimental condition is endothermic in nature. The values of DeltaHi found are in conformity with the ion exchange sorption of xanthate by the chalcopyrite.

Adsorption↗
PubMed2004

Surface charge properties of Fe2O3 in aqueous and alcoholic mixed solvents.

Iron oxide (Fe2O3) was identified and characterized by surface area, X-ray diffractometry, and FTIR analyses. Surface charge densities, point of zero charge (PZC), and surface ionization constants were determined from the potentiometric titration data in various aqueous and aqueous organic mixed solvents in the temperature range 293-313 K. The surface charge densities were observed to decrease with the increase in temperature and concentration of metal ions in both the aqueous and aqueous organic mixed solvents. The absolute values of the surface charge density were found to change in the order aqueous > aqueous/methanol > aqueous/ethanol. Further, the PZC of the iron oxide was observed to shift to the higher pH values in the order ethanol > methanol > aqueous solution, which indicated a decrease in the acidity of the surface -OH groups. The pKa1 and pKa2 values of iron oxide were also determined and then used for determination of the surface potential (psi0) of the solid in aqueous and aqueous organic mixed solvents. The surface potential-surface charge curves generally supplemented the results derived from psi0-pH curves.

Journal Article↗
PubMed2004

Temperature effect on phosphate sorption by iron hydroxide.

The ion exchange sorption of phosphate on Fe(OH)3 is studied as a function of temperature (25-55 degrees C) and concentration (1.49-3.23 mmol l(-1)). The mechanism of sorption is observed to be the exchange of OH- anions from the adsorbent surface by those of H2PO4- and HPO4(2-) from the aqueous solution. An equation developed in the Langmuir formalism is used to explain the ion exchange sorption of phosphate on Fe(OH)3. The isosteric heat of sorption illustrates that the uptake of phosphate on Fe(OH)3 takes place through an anion exchange process, involving both the phosphate anions H2PO4- and HPO4(2-). Further, at higher temperature the solid prefers the HPO4(2-) anions forming a binuclear bridging complex.

Adsorption↗
PubMed2004

Phosphate/sulphate exchange studies on Amberlite IRA-400.

The sorption behaviour of phosphate on strong basic anion exchanger, Amberlite IRA-400 (SO4(2-) form) is studied as a function of pH (3-11) at two different initial concentration ranges (0.161 - 0.807 mmol l(-1), 3.874 - 6.134 mmol l(-1)) at 25 degrees C. The stiochiometry of the exchange reactions is observed to be dependent upon concentration and pH of the solutions. It is suggested that the sorption of phosphate takes place initially as PO4(3-) followed by HPO4(2-)/H2PO4(-). The data obtained is explained with the help of a modified Langmuir and mass law action equations.

Adsorption↗
PubMed2003

Selective removal of Pb2+ by AlPO4.

Aluminium(III) phosphate was observed to have a very high selectivity towards Pb2+ ions. Under similar conditions, the sorption capacities of the exchanger were observed to follow the order: Pb2+ > Zn2+ > Ni2+ > Co2+. The potentiometric titration data were used to determine the deprotonation constants (pKa) of AlPO4, which were dependent upon the temperature and nature of the metal cations present in the aqueous phase. Different physical methods i.e. FTIR, EPM and the wet chemical analyses were used to investigate the uptake mechanism of Pb2+ by the solid, which showed that no new solid phases were present in the solid residue after sorption of Pb2+ at pH 5. The exchange between protons from the surfaceand Pb2+ from solutions was found to be responsible for Pb2+ sorption by aluminum(III) phosphate.

Aluminum Compounds↗
PubMed2003

The mechanisms of Ni2+ ions sorption by AlPO4.

Sorption of Ni2+ ions by AlPO4 is studied as a function of concentrations and temperature at pH 7. Potentiometric titration, dissolution and FTIR studies are employed to determine the mechanism of the process of the uptake of Ni2+ ions which is found to be both the ion exchange and the surface precipitation of the corresponding metal phosphates. Freundlich equation is found applicable to the sorption data, and is employed to evaluate the thermodynamic parameters deltaH(o) and deltatS(o).

Adsorption↗
PubMed2002

The sorption of divalent metal ions on AlPO4.

The sorption of Cu(2+), Pb(2+), Ni(2+), and Cd(2+) ions on the aluminum(III) phosphate was observed to increase with increases in the concentration, temperature, and pH of the system. The apparent dissociation (pK(a)), binding (pK(b)) and exchange (pK(ex)) constants of aluminum(III) phosphate were evaluated and found to be dependent upon the temperature and nature of the metal cations. The values of the dissociation constants (pK(a)) followed the order Pb(2+)<Cu(2+)<Cd(2+)<Ni(2+)<K(+), opposite to the values of the binding constants and selectivity shown by the solid. Ion exchange between protons from the surface and metal cations from aqueous solution was found to be responsible for the metal ions sorption by AlPO(4). The values of the dissociation (pK(a)) and exchange (pK(ex)) constants were used to estimate the corresponding apparent thermodynamic parameters (DeltaH(o)(diss), DeltaS(o)(diss) and DeltaH(o)(exch), DeltaS(o)(exch)). The values of DeltaH(o)(diss) and DeltaH(o)(exch) were found to be positive, which showed that both the dissociation and exchange processes were endothermic in nature. The DeltaS(o)(diss) and DeltaS(o)(exch) were also found to be positive, which showed that both the deprotonation and exchange processes on the AlPO(4) were entropy driven and spontaneous.

Adsorption↗
PubMed2002

Sorption mechanism of Co2+ ions by AlPO4.

Sorption studies were conducted for Co2+ ions on AlPO4 at different concentrations and temperatures. Sorption of Co2+ was found to increase with increase in concentration and temperature. To determine the mechanism of the sorption process, dissolution of AlPO4 in the presence of Co2+ ions and desorption studies were performed which indicated the mechanism of sorption to be the ion exchange followed by precipitation. FTIR studies were also employed to confirm the proposed mechanism.

Adsorption↗
PubMed2002

Selective removal of chromates by macroporous exchanger Amberlyst A-21.

Sorption studies of chromate on weakly basic macroporous anion exchanger Amberlyst A-21 were performed as a function of pH (2 - 9), temperature (20 - 40 degrees C) and concentration (0.4 - 80 mmol.l(-1)). Chromate sorption was observed to decrease with the increase in initial pH of the solution, with a sorption maxima at pH 2 and increased with the increase in temperature. The changes in pH and in the ratio of choride ions released to chromate ions sorbed suggested that the anion exchange process was accomanied by hydrolysis and Donnan invasion. The FTIR spectra and isoeteric heat of sorption besides showing the hydrolysis / Donnan invasion of resin under different experimental conditions of concentration, pH and temperature also showed the dimerization of the chromate species inside the resin phase.

Adsorption↗
PubMed2001

Cooling is a potent vasodilator of deep vessels in the rat.

The objectives of this study were to determine the effect of cooling on smooth muscle tone of the pulmonary artery and aorta and to clarify the basic mechanism of these responses. We recorded isometric tension in smooth muscle strips of rat pulmonary artery and aorta in organ baths during stepwise cooling. Cooling responses were tested before and after the addition of various standard agents that interfere with known neurogenic (autonomic blockers, tetrodotoxin) and myogenic mechanisms (calcium channel blockers) of relaxation. We also examined the hypothesis of the presence of a cooling-released substance. Stepwise cooling (37degrees C to 4 degrees C) of aortic smooth muscle induced reproducible graded relaxations that were inversely proportional to temperature. Cooling-induced relaxation was not dependent on a neural mechanism nor the release of neurotransmitters or a cooling-released substance such as NO or CO. Cooling of pulmonary arterial and aortic smooth muscle preparations induced a graded myogenic relaxation inversely proportional to the cooling temperature. The mechanism is not dependent on local nervous or known mediators but related to a direct physico-chemical effect of cooling.

Animals↗