Colloidal Assemblies of Oriented Maghemite Nanocrystals and their NMR Relaxometric Properties

Elevated-temperature polyol-based colloidal-chemistry approach allows for the development of size-tunable (50 and 86 nm) assemblies of maghemite iso-oriented nanocrystals, with enhanced magnetization. 1H-Nuclear Magnetic Resonance (NMR) relaxometric experiments show that the ferrimagnetic cluster-like colloidal entities exhibit a remarkable enhancement (4 to 5 times) in the transverse relaxivity, if compared to that of the superparamagnetic contrast agent Endorem, over an extended frequency range (1-60 MHz). The marked increase of the transverse relaxivity r2 at a clinical magnetic field strength (1.41 T), which is 405.1 and 508.3 mM-1 s-1 for small and large assemblies respectively, allows to relate the observed response to the raised intra-aggregate magnetic material volume fraction. Furthermore, cell tests with murine fibroblast culture medium confirmed the cell viability in presence of the clusters. We discuss the NMR dispersion profiles on the basis of relaxivity models to highlight the magneto-structural characteristics of the materials for improved T2-weighted magnetic resonance images.Comment: Includes supporting informatio

A double-blind study to determine the maximum tolerated dose of ethionamide, when administered twice-weekly to patients with pulmonary tuberculosis

ATI earlier report from this Centre (Tuber-culosis Chemotherapy Centre, Madras, 1964) showed that a fully supervised twice-weekly regimen of streptomycin plus high-dosage isoniazid was highly effective in the treatment of patients with newly-diagnosed bacteriologi-cally confirmed pulmonary tuberculosis. How-ever, this regimen involves intramuscular injections of streptomycin and may not always be easy to organize, especially in rural areas and in developing countries with limited resources. For this reason, it was decided to investigate the possibility of replacing strepto-mycin in the twice-weekly regimen by two oral drugs, namely ethionamide and PAS. Ethiona-mide was chosen since, apart from isoniazid and streptomycin, it was the most potent drug available at the time, and PAS was included with a view to enhance the efficacy of the regimen. Finally, it was decided that the patients should be given an intensive phase of daily treatment with streptomycin, PAS and isoniazid for two weeks. Experiments in the guinea-pig had shown that the size of the individual dose of a drug needed to be increased as the interval between successive doses was increased (Dickinson & Mitchison, 1966). As PAS is bulky and the dosage of isoniazid in the twice-weekly regimen was already high, namely 15 mg./kg. body-weight, it was decided to explore the possibility of increasing the dosage of ethionamide to a level higher than that usually employed (0.5— 1.0 g.) in daily regimens. An investigation was therefore undertaken to determine the maximum tolerated dose of ethionamide. when administered twice-weekly together with isonia-zid plus PAS. Since the assessment of ethio-namide intolerance is largely subjective, the study was conducted ‘double-blind’ with respect to the dosage of ethionamide

Rate of Inactivation of Isoniazid in South Indian Patients with Pulmonary Tuberculosis 2. Clinical Implications in the Treatment of Pulmonary Tuberculosis with Isoniazid either Alone or in Combination with PAS

A series of studies on the rate of inactivation of isoniazid in Indian patients with pulmonary tuberculosis undergoing domiciliary chemotherapy with isoniazid, alone or in combination with p-aminosalicylic acid, has recently been undertaken by the Tuberculosis Chemotherapy Centre, Madras. In the first study, the serum isoniazid levels of the patients were determined four-and-a-half hours after intramuscular administration of a standard dose of 3 mg/kg body-weight of isoniazid and, according to whether the serum level was 0.58 μg/ml or above, or less than 0.58 μg/ml, the patient was classified as a slow or as a rapid inactivator. The present paper describes the second of these studies, in which the response to treatment of the slow and the rapid inactivators was compared. The results of this investigation suggested that there might be an association between response to treatment and rate of inactivation of isoniazid, since the slow inactivators were more often culturenegative during treatment and showed a higher proportion of individuals with bacteriologically quiescent disease at I2 months and a lower proportion with radiographic deterioration at six months than the rapid inactivators, while the slow inactivators who deteriorated radiographically or clinically to an extent warranting a change of treatment during the two years did so later than the corresponding rapid inactivators. There was slight evidence that the slow and the rapid inactivators differed in the speed of conversion to bacteriological negativity of those patients whose disease was bacteriologically quiescent at 12 months, but no evidence that they differed in the degree of positivity of sputum specimens that were positive on culture at six, nine or 12 months, or in the frequency with which the patients showed moderate or greater radiographic improvement at six months

Iron bioavailability in two commercial cultivars of wheat: a comparison between wholegrain and white flour and the effects of nicotianamine and 2'-deoxymugineic acid on iron uptake into Caco-2 cells

Iron bioavailability in unleavened white and wholegrain bread made from two commercial wheat varieties was assessed by measuring ferritin production in Caco-2 cells. The breads were subjected to simulated gastrointestinal digestion and the digests applied to the Caco-2 cells. Although Riband grain contained a lower iron concentration than Rialto, iron bioavailability was higher. No iron was taken up by the cells from white bread made from Rialto flour or from wholegrain bread from either variety, but Riband white bread produced a small ferritin response. The results probably relate to differences in phytate content of the breads, although iron in soluble monoferric phytate was demonstrated to be bioavailable in the cell model. Nicotianamine, an iron chelator in plants involved in iron transport, was a more potent enhancer of iron uptake into Caco-2 cells than ascorbic acid or 2'-deoxymugineic acid, another metal chelator present in plants

Harnessing genetic potential of wheat germplasm banks through impact-oriented-prebreeding for future food and nutritional security

The value of exotic wheat genetic resources for accelerating grain yield gains is largely unproven and unrealized. We used next-generation sequencing, together with multi-environment phenotyping, to study the contribution of exotic genomes to 984 three-way-cross-derived (exotic/elite1//elite2) pre-breeding lines (PBLs). Genomic characterization of these lines with haplotype map-based and SNP marker approaches revealed exotic specific imprints of 16.1 to 25.1%, which compares to theoretical expectation of 25%. A rare and favorable haplotype (GT) with 0.4% frequency in gene bank identified on chromosome 6D minimized grain yield (GY) loss under heat stress without GY penalty under irrigated conditions. More specifically, the ‘T’ allele of the haplotype GT originated in Aegilops tauschii and was absent in all elite lines used in study. In silico analysis of the SNP showed hits with a candidate gene coding for isoflavone reductase IRL-like protein in Ae. tauschii. Rare haplotypes were also identified on chromosomes 1A, 6A and 2B effective against abiotic/biotic stresses. Results demonstrate positive contributions of exotic germplasm to PBLs derived from crosses of exotics with CIMMYT’s best elite lines. This is a major impact-oriented pre-breeding effort at CIMMYT, resulting in large-scale development of PBLs for deployment in breeding programs addressing food security under climate change scenarios

Activation and Deactivation of a Robust Immobilized Cp*Ir-Transfer Hydrogenation Catalyst: A Multielement in Situ X-ray Absorption Spectroscopy Study

A highly robust immobilized [Cp*IrCl2]2 precatalyst on Wang resin for transfer hydrogenation, which can be recycled up to 30 times, was studied using a novel combination of X-ray absorption spectroscopy (XAS) at Ir L3-edge, Cl K-edge, and K K-edge. These culminate in in situ XAS experiments that link structural changes of the Ir complex with its catalytic activity and its deactivation. Mercury poisoning and “hot filtration” experiments ruled out leached Ir as the active catalyst. Spectroscopic evidence indicates the exchange of one chloride ligand with an alkoxide to generate the active precatalyst. The exchange of the second chloride ligand, however, leads to a potassium alkoxide–iridate species as the deactivated form of this immobilized catalyst. These findings could be widely applicable to the many homogeneous transfer hydrogenation catalysts with Cp*IrCl substructure