F-18 FP-CIT PET in Multiple System Atrophy of the Cerebellar Type: Additional Role in Treatment

We evaluated the difference in the status of dopamine transporters (DATs) depending on Parkinsonism, cerebellar, and autonomic features using F-18 FP-CIT positron emission tomography (PET) in multiple system atrophy with cerebellar ataxia (MSA-C). We also assessed whether the DAT PET could be useful in the management of MSA-C. Forty-nine patients who were clinically diagnosed as possible to probable MSA-C were included. Based on the F-18 FP-CIT PET results, patients were classified into normal (n=25) and abnormal (n=24) scan groups. There were statistically significant differences in rigidity, bradykinesia, postural instability, asymmetry, and specific uptake ratio (SUR) between the two groups but no significant differences in tremor and cerebellar/autonomic symptoms. Dopaminergic medications were administered to 22 patients. All seven patients with normal scans showed no change, while 10 of the 15 patients with abnormal scans showed clinical improvement. There was a trend of a negative correlation between levodopa equivalent dose and SUR, but it was not statistically significant. DAT imaging, such as F-18 FP-CIT PET, may be useful in predicting the response to dopaminergic medication regardless of cerebellar/autonomic symptoms in MSA-C. In addition to being used for the diagnosis of the disease, it may be used as a treatment decision index

Monitoring of multi-frequency polarization of gamma-ray bright AGNs

We started two observing programs with the Korean VLBI Network (KVN) monitoring changes in the flux density and polarization of relativistic jets in gamma-ray bright AGNs simultaneously at 22, 43, 86, 129 GHz. One is a single-dish weekly-observing program in dual polarization with KVN 21-m diameter radio telescopes beginning in 2011 May. The other is a VLBI monthly-observing program with the three-element VLBI network at an angular resolution range of 1.0--9.2 mas beginning in 2012 December. The monitoring observations aim to study correlation of variability in gamma-ray with that in radio flux density and polarization of relativistic jets when they flare up. These observations enable us to study the origin of the gamma-ray flares of AGNs.Comment: 4 pages, 4 figures, Proceedings of the conference "The innermost regions of relativistic jets and their magnetic fields", Granada, Spai

In vivo and in vitro studies of Mgs1 suggest a link between genome instability and Okazaki fragment processing

The non-essential MGS1 gene of Saccharomyces cerevisiae is highly conserved in eukaryotes and encodes an enzyme containing both DNA-dependent ATPase and DNA annealing activities. MGS1 appears to function in post-replicational repair processes that contribute to genome stability. In this study, we identified MGS1 as a multicopy suppressor of the temperature-sensitive dna2Δ405N mutation, a DNA2 allele lacking the N-terminal 405 amino acid residues. Mgs1 stimulates the structure-specific nuclease activity of Rad27 (yeast Fen1 or yFen1) in an ATP-dependent manner. ATP binding but not hydrolysis was sufficient for the stimulatory effect of Mgs1, since non-hydrolyzable ATP analogs are as effective as ATP. Suppression of the temperature-sensitive growth defect of dna2Δ405N required the presence of a functional copy of RAD27, indicating that Mgs1 suppressed the dna2Δ405N mutation by increasing the activity of yFen1 (Rad27) in vivo. Our results provide in vivo and in vitro evidence that Mgs1 is involved in Okazaki fragment processing by modulating Fen1 activity. The data presented raise the possibility that the absence of MGS1 may impair the processing of Okazaki fragments, leading to genomic instability

Linear Polarization of Class I Methanol Masers in Massive Star-forming Regions

Class I methanol masers are found to be good tracers of the interaction between outflows from massive young stellar objects with their surrounding media. Although polarization observations of Class II methanol masers have been able to provide information about magnetic fields close to the central (proto)stars, polarization observations of Class I methanol masers are rare, especially at 44 and 95 GHz. We present the results of linear polarization observations of 39 Class I methanol maser sources at 44 and 95 GHz. These two lines are observed simultaneously with one of the 21 m Korean VLBI Network telescopes in single-dish mode. Approximately 60% of the observed sources have fractional polarizations of a few percent in at least one transition. This is the first reported detection of linear polarization of the 44 GHz methanol maser. The two maser transitions show similar polarization properties, indicating that they trace similar magnetic environments, although the fraction of the linear polarization is slightly higher at 95 GHz. We discuss the association between the directions of polarization angles and outflows. We also discuss some targets having different polarization properties at both lines, including DR21(OH) and G82.58+0.20, which show the 90° polarization angle flip at 44 GHz