Development of a process for routine production of123I using the127I(p, 5n)123Xe→123I reaction

The object of this paper is to give details of a production method for¹²³I, now in routine use at Harwell. We employ the (p, 5n) reaction, irradiating a liquid target of di-iodomethane (CH₂I₂) spiked with additional iodine, with 58 MeV protons. A yield of ∼9 mCi/μAh is obtained; the only detectable radionuclidic impurity is¹²⁵I, present to the extent of ∼0.15% by activity at the time of separation of Xe from I.     

Radiochemical purity of 123I for medical use (author's transl)

123I for use in clinical diagnostic procedures has been produced by bombarding antimony with 40 MeV 3He particles. The purity of 123I was measured with a Ge(Li)spectrometer and a low energy Ge(Li) detector. The 123I-product was followed for 1.5 months with a well-type NaI scintillation counter to establish the half-life and confirm the identity of the nuclides. In order to minimize the yield of 121I the optimum cooling time and chemical procedures are presented. After 20 h cooling, the 121I, 124I and 125I contaminants were about 1.8, 4.3 and 0.04% respectively. These values were in agreement with those calculated from the thick-target yield curves. The calculated absorbed dose to the thyroid by the 123I and by-product nuclides were only 4.3 and 7.3% of 131I. 123I could be measured at the window of 99mTc of a NaI scintillation camera and a curie-meter with an error of 10%.     

Kinetics of 17-(123I) iodoheptadecanoic acid in myocardium of rats

Myocardial uptake and turnover of 17-(¹²³I)-iodoheptadecanoic acid, injected i.v., was studied in rats. Kinetics of radioactivity incorporated into myocardial tissue and heart lipids as well as myocardial radioactivity recovered as¹²³I iodide were determined. Maximal heart uptake of IHA (7.9% dose/g heart) was observed as early as 30 sec., p.i., followed by mono-component elimination period. Already 10 to 30 sec p.i. 70 to 80% of total myocardial radioactivity was recovered as¹²³I iodide. IHA was incorporated only in modest amounts into myocardial phospholipids and triglycerides. Time course of total myocardial radioactivity grossly paralleled that recovered as¹²³I iodide. These findings indicate stringent limitations in utility of IHA as a tracer for assessment of β-oxidation.     

Determination of the ratio of copper(I) to copper(II) present as traces in ionic crystals

A polarographic method is described for the determination of traces of copper in ionic crystals, which also allows the determination of the ratio of the concentrations of copper(II) and copper(I).     

Fabrication of a novel temperature sensitive poly(N-isopropyl-3-butenamide) hydrogel

To investigate the temperature sensitive mechanism and develop temperature sensitive materials, a novel poly(N-isopropyl-3-butenamide) (PNIPBAm) hydrogel was designed and synthesized. The maximum swelling ratio, temperature dependence of swelling ratio and deswelling/reswelling kinetics of the resulted PNIPBAm hydrogel were characterized. The data obtained exhibited that the temperature sensitivity of the PNIPBAm hydrogel depended on the amount of crosslinker, i.e. the temperature sensitivity decreased with the increasing content of crosslinker. This novel temperature sensitive hydrogel would have the potential applications in bioengineering and biotechnology fields.     

Experiences in the routine production of123I via the124Te(p, 2n)123I reaction with a low energy cyclotron

This paper deals with the results and experimental observations obtained in routine production of¹²³I via¹²⁴Te(p, 2n)¹²³I reaction, using the low energy cyclotron (protons, E_max=22 MeV) at the German Cancer Research Center in Heidelberg. The reaction was studied during the past 4 years using¹²⁴TeO₂ targets with various levels of enrichment. The purpose of the study was to determine which target material provided the highest quality and most economical production of¹²³I. A viable routine production was defined as one in which¹²³I could be conveniently and reproducably prepared in reasonable purity while maintaining a low cost for the entire process. Different methods of sublimation of¹²³I activity from the¹²⁴TeO₂ target were examined to determine the optimal conditions for recovery of radioactivity and recycling of target material. A rapid method is described which permits quantitative separation of¹²³I while allowing only a negligible loss of¹²⁴TeO₂.     

The Horwitz ratio (HorRat): A useful index of method performance with respect to precision

The Horwitz ratio (HorRat) is a normalized performance parameter indicating the acceptability of methods of analysis with respect to among-laboratory precision (reproducibility). It is the ratio of the observed relative standard deviation among laboratories calculated from the actual performance data, RSDR (%), to the corresponding predicted relative standard deviation calculated from the Horwitz equation PRSDR (%) = 2C(-0.15), where C is the concentration found or added, expressed as a mass fraction. It is more or less independent of analyte, matrix, method, and time of publication (as a surrogate for the state of the art of analytical chemistry). It is now one of the acceptability criteria for many of the recently adopted chemical methods of analysis of AOAC INTERNATIONAL, the European Union, and other European organizations dealing with food analysis (e.g., European Committee for Standardization and Nordic Analytical Committee). The origin and applications of the formula are described. Consistent deviations from the ratio on the low side (values <0.5) may indicate unreported averaging or excellent training and experience; consistent deviations on the high side (values >2) may indicate inhomogeneity of the test samples, need for further method optimization or training, operating below the limit of determination, or an unsatisfactory method.     

Regional cerebral blood flow in cerebrovascular disease studied using N-isopropyl-p-(123I) iodoamphetamine

Twenty-one patients with cerebrovascular disease (5 with hemorrhage, 10 with infarction, 2 with TIA, 4 with motor disturbance of unknown cause) were studied using N-isopropyl-p-(123I)iodoamphetamine (123I-IMP) and single photon emission CT. In 3 of 5 cases with cerebral hemorrhage, perfusion defects were shown in and around the region of hematomas, furthermore, one of the cases with internal capsular hematoma, the perfusion defect extended to the cortical area corresponding to the neurological pathway. In one case with MCA infarction, the perfusion defect was greater and clearer than the low density area on X-ray computed tomography (CT). These results revealed the 123I-IMP study provides physiological information in contrast with X-ray CT which provides anatomical information. In 3 of 9 cases with multiple small deep hemispheric infarctions on X-ray CT, the perfusion to the basal ganglia was suspected to be decreased on 123I-IMP images. However, this visual findings was not definitive and, in fact, the diseased side was not always consistent with the clinical findings. For quantitative analysis, symmetrical regions of interest (ROIs) were constructed both basal ganglia and the ratio of average counts over the ROI to those over the whole slice was calculated. In the small infarction group, the mean +/- S.D. of the values was 0.89 +/- 0.09 in right and 0.89 +/- 0.08 in left. Although the values were not significantly different from those of normal subjects (0.99 +/- 0.02 in right, 0.97 +/- 0.03 in left), they distributed in the range less than normal in 5 of 9 cases. This method was thought to be useful and practical to evaluate the cerebral blood flow in basal ganglia of patients with deep hemispheric infarction.     

Electron transfer. 123. Competitive redox reactions involving a Cobalt(I) intermediate

he hypophosphito derivative of Co^III, (NH₃)₅CoO₂PH₂ ²⁺, decomposes in basic media, yielding Co(II) quantitatively, along with a 1:1 mixture of hypophosphite and phosphite. Earlier studies point to a cobalt (I) intermediate, which rapidly reduces a second molecule of Co(III) reactant to Co(II). In the presence of an external cobalt (III) oxidant (Co³X), the latter competes with the hypophosphito complex for Co(I), lowering the yield of free hypophosphite. From the ratio of phosphorus products (P³/P¹), evaluated by proton decoupled ³¹P NMR, the relative reactivities (k_t/k_c) of the external Co(III) “traps” and the hypophosphito complex may be determined. A log-log plot comparing values of k_t/k_c with rates for reductions of the same series of Co(III) oxidants with Ru(NH₃)₆ ²⁺ (k_Ru values) is badly scattered with a slope of only 0.23, well below the value of unity stipulated by the Marcus model, indicating that an outer-sphere mechanism cannot operate for all of the Co(III)-Co(I) reactions and may not operate for any, except for that with Co(NH₃)₅(py)₃₊. Among the carboxylato-substituted oxidants, there are no rate enhancements by neighbouring pyridine, -SR,-OH, -CHO, or -SO₃H functions, in contrast to the accelerations previously observed for reductions by Cr(II), Eu(II) and Ti(III), which are attributed to intermediacy of chelate-stabilized precursor complexes. It is suggested that the Co(III)-Co(I) reactions, which determine the ratio of phosphorus products, are much more rapid than the ligand substitution at the Co(I) center which must precede chelate formation, and that the latter therefore does not intervene significantly in the redox processes.     

Glycosaminoglycan in cerebrum, cerebellum and brainstem of young sheep brain with particular reference to compositional and structural variations of chondroitin-dermatan sulfate and hyaluronan

Recent advances in the structural biology of chondroitin sulfate chains have suggested important biological functions in the development of the brain. Several studies have demonstrated that the composition of chondroitin sulfate chains changes with aging and normal brain maturation. In this study, we determined the concentration of all glycosaminoglycan types, i.e. chondroitin sulfate, dermatan sulfate, keratan sulfate, heparan sulfate, hyaluronan and chondroitin in cerebrum, cerebellum and brainstem of young sheep brain. In all cases, chondroitin sulfate was the predominant glycosaminoglycan type, comprising about 54-58% of total glycosaminoglycans, with hyaluronan being present also in significant amounts of about 19-28%. Of particular interest was the increased presence of the disulfated disaccharides and dermatan sulfate in cerebellum and brainstem, respectively, as well as the detectable and measurable occurrence of chondroitin in young sheep brain. Among the three brain areas, cerebrum was found to be significantly richer in chondroitin sulfate and hyaluronan, two major extracellular matrix components. These findings imply that the extracellular matrix of the cerebrum is different from those of cerebellum and brainstem, and probably this fact is related to the particular histological and functional characteristics of each anatomic area of the brain. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Fundamental study for SPECT imaging with 123I produced by (p, 5n) reaction

The effects of higher-energy photon from 123I (p, 5n) on the SPECT image quality were evaluated. The quality was evaluated by image contrast and %rms. Image contrast had similar tendency to planar and SPECT FWHM value. %rms was affected by septal penetration. Using 140 keV high resolution collimator (140 keV HR), image contrast was superior to that for 300 keV medium energy collimator (300 keV ME), but septal penetration rate (SPR) was 18% and %rms was 10.5. When quantitation is required, the collimator with less SPR than 18% is recommended for SPECT imaging. Using 300 keV ME, SPR was 0.05%, but spatial resolution and image contrast were inferior to that for 140 keV HR.     

Ligand-mediated decarbonylation as an efficient synthetic method to Re(I) and Re(II) dicarbonyl complexes

A novel synthetic method based on a ligand-mediated decarbonylation reaction of complexes of the common fac-[Re(CO)3]+ core efficiently yields Re(I) and Re(II) dicarbonyl species.     

Experimental study on the collimator for increasing the resolution of N-isopropyl-p-(123I)iodoamphetamine (IMP) SPECT imaging of the brain

This study was carried out to design a new collimator for the present 123I-IMP SPECT imaging of the brain, which is hindered by the contamination of 124I and 126I. In this study we intended to increase spacial resolution along the transaxial direction and, at the same time, to compensate for the decrease of sensitivity by sacrificing the resolution along the axial direction to some extent. For this purpose, we developed 4 kinds of slat type units; ultrahigh resolution (UHR), high resolution (HR), high sensitivity (HS), and ultrahigh sensitivity (UHS). In practice, either UHR or HR is set to the detector together with either HS or UHS. After testing 4 kinds of combinations, we found that the combination of UHR-HS gave us far better images than those obtained with the conventional medium energy parallel hole collimator and was best suited for 123I-IMP SPECT imaging of the brain at present. We are now thinking of fusing these two units together into one collimator.     

Experiences in routine production of123I in Manitoba for delivery to other Canadian centres

An experience at¹²³I production with a low beam current cyclotron used in combination with the¹²⁴Te(p, 2n)¹²³I reaction on 90.8% enrichment¹²⁴Te is described.     

Sensitivity of silver(I) complexes of a pyrimidine-hydrazone ligand to solvent, counteranion, and metal-to-ligand ratio changes

Metal complexation studies were performed with AgSO(3)CF(3) and AgBF(4) and the ditopic pyrimidine-hydrazone ligand 6-(hydroxymethyl)pyridine-2-carboxaldehyde (2-methylpyrimidine-4,6-diyl)bis(1-methylhydrazone) (1) in both CH(3)CN and CH(3)NO(2) in a variety of metal-to-ligand ratios. The resulting complexes were studied in solution by NMR spectroscopy and in the solid state by X-ray crystallography. Reacting either AgSO(3)CF(3) or AgBF(4) with 1 in either CH(3)CN or CH(3)NO(2) in a 1:1 metal-to-ligand ratio produced a double helicate in solution. This double helicate could be converted into a linear complex by increasing the metal-to-ligand ratio; however, the degree of conversion depended on the solvent and counteranion used. Attempts to crystallize the linear AgSO(3)CF(3) complex resulted in crystals with the dimeric structure [Ag(2)1(CH(3)CN)(2)](2)(SO(3)CF(3))(4) (2), while attempts to crystallize the AgSO(3)CF(3) double helicate from CH(3)CN resulted in crystals of another dimeric complex, [Ag(2)1(SO(3)CF(3))(CH(3)CN)(2)](2)(SO(3)CF(3))(2)·H(2)O (3). The AgSO(3)CF(3) double helicate was successfully crystallized from a mixture of CH(3)CN and CH(3)NO(2) and had the structure [Ag(2)1(2)](SO(3)CF(3))(2)·3CH(3)NO(2) (4). The linear AgBF(4) complex could not be isolated from the double helicate in solution; however, crystals grown from a solution containing both the AgBF(4) double helicate and linear complexes in CH(3)CN had the structure [Ag(2)1(CH(3)CN)(2)](BF(4))(2) (5). The AgBF(4) double helicate could only be crystallized from CH(3)NO(2) and had the structure [Ag(2)1(2)](BF(4))(2)·2CH(3)NO(2) (6).     

Binding of lead to collagen type I and V and alpha2(I) CNBr (3,5) fragment by a modified Hummel-Dreyer method.

Binding of lead (as lead acetate) to collagen type I alpha, and alpha2 chains, collagen type V and a large cyanogen bromide fragment of type I collagen [alpha2(I)CB(3,5)] was investigated by the large-zone Hummel-Dreyer method. It was demonstrated that two categories of binding sites exist in the collagen molecule, the number of which correlates rather well with the available aspartic and glutamic acid residues. Similar results were obtained for all collagen chains (fragments) used. The number of sites thus obtained was compared with the cross-striation pattern (reflecting areas where lead is bound) of the SLS form of collagen type I (alpha1 chain); it is suggested that the number of bands seen in the SLS form reflects primarily the number of available aspartic acid residues in the molecule. The association constants obtained are comparable with the low affinity interactions seen e.g., between Cu and bovine serum albumin.     

Oxidative addition of dimethylphosphite to iridium(I) and rhodium(I) complexes: Stereoselective reduction of 4-t-butylcyclohexanone

Dimethylphosphite, (CH₃O)₂P(O)H, adds oxidatively to iridium(I) and rhodium(I) complexes to give hydrido-iridium(III) or -rhodium(III) dimethylphosphonate complexes. A complex Ir(H)Cl[P(O)(OCH₃)₂][P(OH)(OCH₃)₂]₃ obtained from [IrCl(C₈H₁₄)₂]₂ and dimethylphosphite catalyses the stereo-selective reduction of 4-t-butylcyclohexanone to $\text{97}\text{3}$cis/trans-4-t-butylcyclohexanol, the ratio being identical with that obtained using the Henbest catalyst iridium(IV) chloride, phosphorous acid or one of its esters, and aqueous isopropanol.