Comparison between Dual-Energy CT and Quantitative Susceptibility Mapping in Assessing Brain Iron Deposition in Parkinson Disease

BACKGROUND AND PURPOSE

Both dual-energy CT and quantitative susceptibility mapping can evaluate iron depositions in the brain. The purpose of this study was to compare these 2 techniques in evaluating brain iron depositions in Parkinson disease.

MATERIALS AND METHODS

Forty-one patients with Parkinson disease (Parkinson disease group) and 31 age- and sex-matched healthy controls (healthy control group) were included. All participants underwent brain dual-energy CT and quantitative susceptibility mapping. ROIs were set bilaterally in the globus pallidus, substantia nigra, red nucleus, caudate nucleus, and putamen. CT values and magnetic susceptibility values were obtained in each ROI. Differences in CT values and magnetic susceptibility values between the Parkinson disease and healthy control groups were compared, followed by analysis of receiver operating characteristic curves. Correlations between CT values and magnetic susceptibility values were then evaluated.

RESULTS

The CT values of the bilateral globus pallidus, substantia nigra, and red nucleus were higher in the Parkinson disease group (P < .05). The magnetic susceptibility values of the bilateral globus pallidus and substantia nigra were higher in the Parkinson disease group (P < .05). The CT value of the right globus pallidus in linear fusion images had the highest diagnostic performance (0.912). Magnetic susceptibility values of the bilateral globus pallidus in the Parkinson disease group were positively correlated with CT values at the level of 80 kV(peak), linear fusion images, and SN150 kV(p) (r = 0.466∼0.617; all, P < .05).

CONCLUSIONS

Both dual-energy CT and quantitative susceptibility mapping could assess excessive brain iron depositions in Parkinson disease, and we found a positive correlation between CT values and magnetic susceptibility values in the bilateral globus pallidus.

Anion photoelectron spectroscopy and density functional theory study of TM2Sin- (TM = V, Cr; n = 14-20) clusters

We investigated the structural evolution and electronic properties of medium-sized silicon cluster anions doped with two transition metal atoms, TM₂Si_n^- (TM = V, Cr; n = 14-20), by using mass-selective anion photoelectron spectroscopy combined with density functional theory (DFT) calculations. Putative ground state structures of these clusters were obtained by using a genetic algorithm coupled with the DFT calculations. It was found that the two TM atoms tend to form a TM-TM bond, which - except for V₂Si₁₉^- - is shorter than the nearest neighbour distance in the crystalline state of the respective metals. The V₂Si_n^- clusters with n = 14 to 17 exhibit structures based on a silicon hexagonal antiprism, while the larger ones exhibit more fullerene-like cage structures. Cr₂Si_n^- clusters follow the same trend, although with a silicon hexagonal prism structure for n = 14 and 15, and the transition to fullerene-like structures occurring at n = 17. Among these clusters, TM₂Si₁₈^- have the largest average binding energy and second order differences in energy, therefore the highest relative stability. All of the clusters possess total magnetic moment of 1 μB, but with very different contributions from the doped TM atoms. Especially in the Cr doped clusters there is a tendency towards an anitiferromagnetic arrangement of the magnetic moments of the two Cr atoms.

Structures and electronic properties of VSin- (n = 14-20) clusters: a combined experimental and density functional theory study

We present a systematic study of the structures and electronic properties of vanadium-doped silicon cluster anions, VSi_n^- (n = 14-20), by combining photoelectron spectroscopy (PES) measurements and density functional theory (DFT) based theoretical calculations. High resolution PES of low temperature (10 K) clusters are acquired at a photon wavelength of 248 nm. Low-lying structures of VSi_14-20^- are obtained by a genetic algorithm based global minimum search code combined with DFT calculations. Excellent agreement is found between the measured PES and the simulated electron density of states of the putative ground-state structures. We conclude that clusters with sizes n = 14 and n = 15 prefer cage-like structures, with the encapsulated vanadium atom bonding with all silicon atoms, while a fullerene-like motif is more favorable for n ≥ 16. For the sizes n = 16 to 19, the structures consist of a V@Si₁₄ with two, three, four, and five Si atoms on the surface of the cage. For n = 20 the structure consists of a V@Si₁₅ with five Si atoms on the surface of the cage. VSi₁₄^- has the highest stability and stands out as a simultaneous closing of electronic and geometrical shells.

Photoelectron Spectroscopy and Density Functional Investigation of the Structural Evolution, Electronic, and Magnetic Properties of CrSin- (n = 14-18) Clusters

CrSi_n^- (n = 14-18) cluster anions have been investigated by a combination of photoelectron spectroscopy (PES) and first-principles calculations. The lowest-lying structures of the clusters have been determined by a global minimum search based on the genetic algorithm, combined with density functional theory (DFT) calculations. The simulated PES spectra of the lowest-energy isomers are in agreement with the experimental results, which gives strong evidence that the correct structures have been found. While sizes n = 14 and n = 15 prefer cage-like structures based on multi-center bonding within the cage, the larger sizes adopt structures based on fullerene-type cages around the Cr atom, with the additional atoms attached to the cage surface. A Hirshfeld analysis shows that the Cr atoms act as electron donors in all clusters, thus enhancing the electron count in the cage. It also reveals that the magnetic moment of 1μ_B shown by all clusters is mainly contributed by the Cr atom. One interesting exception is size 17, where the Cr atom contributes a small moment antiparallel to that of the silicon cage.

First Report of Pratylenchus neglectus on Winter Wheat in China

Root-lesion nematodes are major pathogens of wheat and have been reported in the United States, Mexico, India, Australia, Egypt, Canary Islands, South Africa, Iran, Japan, the Netherlands, Belgium, Italy, Germany, and Yugoslavia (1). They can also cause injury in a large number of crops, including grasses, cereal grains, and vegetables. In 2009 and 2010, a survey was conducted for nematodes in winter wheat fields near Taian city, Shandong, northern China. Root tissues were stained via the acid fuchsin tissue stain technique, and nematode numbers were recorded under a stereo microscope. Sixty-eight root samples were collected during the winter wheat growing season, and root lesion nematode was found in all samples. The highest average lesion nematode populations in fresh roots were 154.3 nematodes/g in 2009 and 236.7 nematodes/g in 2010. Nematodes were collected from infested wheat roots by a modified Baermann funnel method. Dimensions of the nematodes were: length, 0.42 to 0.54 mm; a, 18.8 to 24.2; b, 4.4 to 5.7; c, 19.8 to 25.4; V, 80.4 to 84.8; and spear, 17.1 to 18.9 μm. DNA was extracted from individual nematodes using liquid nitrogen. Amplification of rDNA-internal transcribed spacer region using the forward primers 5'-CGTAACAAGGTAGCTGTAG-3' and the reverse primer 5'-TTTCACTCGCCGTTACTAAGG-3' yielded a PCR fragment of approximately 900 bp. PCR products were purified using Universal Plant DNA Purification Kit (Tiangen, China) and ligated to the pMD18-T vector system (TaKaRa Bio, Japan) and transformed to E. coli strain DH5α. Plasmid DNA carrying the insert was extracted and used as the template for DNA sequencing. DNA sequencing was carried out in an ABI 3730, compared and aligned using MEGA 5.0. Sequences showed 96% sequence identity with those of Pratylenchus neglectus (GenBank Accession No. FR692291.1). The sequence was submitted to the GenBank database (JX228136). To our knowledge, this is the first report of P. neglectus infesting winter wheat in China. P. neglectus has been reported as causing economically significant damage to wheat production of up to 70% yield loss in the Pacific Northwest. Damage from lesion nematode may therefore be potentially significant to wheat production in Shandong Province, and further information should be obtained on its prevalence. References: (1) P. A. A. Loof. The family Pratylenchidae Thorne, 1949. W. R. Nickle, ed., Manual of Agricultural Nematol. Marcel Dekker, Inc. New York, 1991. (2) R. W. Smiley et al. J. Nematol. 37:45, 2005.

[A review of the studies on fungi and mycotoxins in foodstuffs in Beijing during 1976-1986]

Fungi and mycotoxins contaminating foods in Beijing during 1976-1986 were studied. A total of more than 5,000 food samples classified into 104 kinds of 16 types were examined of analysed. The results showed that the natural occurrence of Aflatoxin B1 in foods in Beijing was not serious, but from the results of analysis 59 cases of food poisoning and food seriously contaminated with moulds, the hazards of fungal contamination of food should receive serious consideration. In order to improve food hygiene and facilitate supervision the author suggested that a mycological standard should be established for marketing foods in China, such as grain, and beverage which are highly susceptible to fungal contamination.