Shahid Pervez

Technetium-99m direct radiolabeling of Lanreotide: a Somatostatin analog

Lanreotide, a synthetic octapeptide analog of a native hormone somatostatin, was labeled with a commonly available, inexpensive radionuclide 99mTc. Labeling was accomplished by reduction of the cysteine bridge, which provided sulfhydryl groups for chelation with 99mTc. Stannous chloride was used as reducing agent, while tartrate acted as transchelating agent. Lanreotide (100 microg), stannous chloride dihydrate (100 microg) and tartaric acid (64 microg) were dissolved in acetate/acetic acid buffer (pH 2.8). After overnight (approximately 18 h) incubation, approximately 444 MBq (12 mCi) 99mTc was added and kept in boiling water for 30 min. More than 97% labeling efficiency was confirmed by RP-HPLC, ITLC-SG and C18 cartridge analysis. Radiolabeling results in one major peak when analyzed by reverse-phase HPLC. The stability of the 99mTc-peptide bond was evaluated by cysteine challenge studies.

Sorption Potential of Styrene‐Divinylbenzene Copolymer Beads for the Decontamination of Lead from Aqueous Media

Abstract The decontamination of lead ions from aqueous media has been investigated using styrene‐divinylbenzene copolymer beads (St‐DVB) as an adsorbent. Various physico‐chemical parameters such as selection of appropriate electrolyte, contact time, amount of adsorbent, concentration of adsorbate, effect of foreign ions, and temperature were optimized to simulate the best conditions which can be used to decontaminate lead from aqueous media using St‐DVB beads as an adsorbent. The atomic absorption spectrometric technique was used to determine the distribution of lead. Maximum adsorption was observed at 0.001 mol L−1 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 0.2 g of adsorbent for 4.83×10−5 mol L−1 lead concentration in two minutes equilibration time. The adsorption data followed the Freundlich, Langmuir, and Dubinin‐Radushkevich (D‐R) isotherms over the lead concentration range of 1.207×10−3 to 2.413×10−2 mol L−1. The characteristic Freundlich constants i.e. 1/n=0.164±0.012 and A=2.345×10−3±4.480×10−5 mol g−1 have been computed for the sorption system. Langmuir isotherm gave a saturated capacity of 0.971±0.011 mmol g−1, which suggests monolayer coverage of the surface. The sorption mean free energy from D‐R isotherm was found to be 18.26±0.75 kJ mol−1 indicating chemisorption involving chemical bonding for the adsorption process. The uptake of lead increases with the rise in temperature. Thermodynamic parameters i.e. ΔG, ΔH, and ΔS have also been calculated for the system. The sorption process was found to be exothermic. The developed procedure was successfully applied for the removal of lead ions from real battery wastewater samples.

188Rhenium-EDTMP: A potential therapeutic bone agent

Bone seeking radiopharmaceuticals such as ethylenediaminetetramethylene phosphonate (EDTMP) complexes of 153Sm and 166Ho are receiving considerable attention for therapeutic treatment of bone metastases. Rhenium-188 has both beta-particle emissions for a therapeutic effect and gamma-emissions for imaging and it is available from an in-house generator system similar to the current 99mTc generator, which makes it convenient for clinical use. The preparation of 188Re-EDTMP is described using 188Re, which was obtained from the alumina-based 188W/188Re generator. Dependence of the radiolabeling yield of 188Re-EDTMP on reducing agent concentration, EDTMP concentration, incubation time, pH and addition of carrier was examined. In the case of optimum conditions, the radiolabeling yields of 188Re-EDTMP were ~98% for carrier-free as well as carrier-added 188Re. The addition of ascorbic acid plays an important role in the stability of carrier-free as well as carrier-added 188Re-EDTMP preparations. The biodistribution of carrier-free and carrier-added 188Re-EDTMP compounds in rats was also studied. The results show that 188Re (carrier-added)-EDTMP is a potential bone pain palliation radiopharmaceutical due to its high skeletal uptake, rapid blood clearance and relatively low soft tissue absorption.

The Fission-Based 99Mo Production Process ROMOL-99 and Its Application to PINSTECH Islamabad

An innovative process for fission based 99Mo production has been developed under Isotope Technologies Dresden (ITD) GmbH (former Hans Walischmiller GmbH (HWM), Branch Office Dresden), and its functionality has been tested and proved at the Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad. Targets made from uranium aluminum alloy clad with aluminum were irradiated in the core of Pakistan Research Reactor-1 (PARR-1). In the mean time more than 50 batches of fission molybdenum-99 (99Mo) have been produced meeting the international purity/pharmacopoeia specifications using this ROMOL-99 process. The process is based on alkaline dissolution of the neutron irradiated targets in presence of NaNO3, chemically extracting the 99Mo from various fission products and purifying the product by column chromatography. This ROMOL-99 process will be described in some detail.

188Rhenium-glucoheptonate: A radiopharmaceutical for intravascular radiation therapy

The preparation of 188Re-glucoheptonate (GH) is described using 188Re, which was obtained from an alumina based 188W/188Re generator. The dependence of the radiolabeling yields of 188Re-GH on reducing agent concentration, GH concentration, pH, temperature and incubation time was examined. In the case of optimum conditions the yield of 188Re-GH was ~99%. The ITLC technique was employed to monitor the different species formed. A biodistribution study of 188Re-GH was carried out in rats and compared to the biological behavior of 99mTc-GH.

Formulation of a freeze-dried kit for 188Re-MAG3 and its quality control

The synthesis of 188Re-MAG3 is described using 188Re, which was obtained from the alumina based 188W/188Re generator. Dependence of the radiolabeling yields of 188Re-MAG3 on reducing agent concentration, Bz-MAG3 concentration, pH, temperature and incubation time was examined. In the case of optimum conditions the yield of 188Re-MAG3 was 98%. TLC and HPLC techniques were employed to monitor the different species formed. Biodistribution study of 188Re-MAG3 was carried out in rats and compared with behavior of 99mTc-MAG3.

Preparation of 188Re-labeled hydroxyapatite for radiosynovectomy

Hydroxyapatite (HA), a natural constituent of bone, was synthesized. HA particles were radiolabeled with 188Re. Radiolabeling efficiency was 95%. In vitro studies showed 5% loss of activity from particles in normal saline over a period of 2 days, whereas a dissociation rate of 9% was observed in human serum albumin.

Comparative studies of S-bridged complexes of 99mTc with fac(S)-[M(aet)3] (M = RhIII, IrIII; aet = 2-aminoethanethiolate)

Abstract fac(S)-[Ir(aet)3] (aet=2-aminoethanethiolate) is N3S3 metalloligand, which forms S-bridged polynuclear complexes with transition metal ions. A complex analogous to [Re{Ir(aet3)}2]3+ was formed by the reaction of 99mTcO4Na and fac(S)-[Ir(aet)3] in the presence of SnCl22H2O. A simple method for radiollabelling of fac(S)-[Ir(aet)3] with 99mTc was developed with radiolabelling efficiency higher than 99%. Effects of SnCl2·2H2O concentration, time and pH on the radiolabelling efficiency were determined and compared with 99mTc-[Rh(aet)3]. 99mTc-[Ir(aet)3] was also characterized by electrophoresis, HPLC, biodistribution studies in rats and scintigraphy in rabbit. Higher uptake by kidneys showed rapid distribution of the labelled fac (S)-[Ir(aet)3]. Scintigrams show that liver, bladder and skeletal uptake were significant. The results of biodistribution showed that 99mTc-[Ir(aet)3] uptake is quite rapid as compared to 99mTc-[Rh(aet)3].

Sorption profile of cadmium ions onto styrene-divinylbenzene copolymer beads

Abstract The sorption behavior of cadmium ions from aqueous media was investigated on styrene-divinylbenzene copolymer beads (StDVB) as an adsorbent. Various physico-chemical parameters were optimized to simulate the best conditions which can be used to decontaminate cadmium ions from aqueous media using StDVB beads as an adsorbent. Maximum adsorption was observed at 0.001 mol L-1 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 0.2 g of adsorbent for 8.89×10-5 mol L-1 of cadmium ions within three minutes equilibration time. The adsorption data followed the Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherms over the cadmium concentration range of 8.89×10-4 to 8.01×10-3 molL-1. The characteristic Freundlich constants, i.e. 1/n=0.243±0.007 and A=1.783×10-3±2.069×10-5 mol g-1 have been computed for the sorption system. Langmuir isotherm gave a saturated capacity of 0.334±0.0123 mmol g-1. The sorption mean free energy from D–R isotherm was found to be 16.31±0.31 kJ mol-1 indicating chemisorption involving chemical bonding for the adsorption process. The uptake of cadmium increased with the rise in temperature. Thermodynamic parameters, i.e. ΔG, ΔH and ΔS have also been calculated for the system. The sorption process was found to be endothermic. The proposed procedure was applied to remove cadmium from tap water and industrial effluent.