Decreased Cortical Thickness and Local Gyrification in Individuals with Subjective Cognitive Impairment

Objective@#Subjective cognitive impairment (SCI) is associated with future cognitive decline. This study aimed to compare cortical thickness and local gyrification index (LGI) between individuals with SCI and normal control (NC) subjects. @*Methods@#Forty-seven participants (27 SCI and 20 NC) were recruited. All participants underwent brain magnetic resonance imaging scanning and were clinically assessed using the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) battery of tests. We compared cortical thickness and LGI between the two groups and analyzed correlations between cortical thickness/LGI and scores on CERAD protocol subtests in the SCI group for region of interests with significant between-group differences. @*Results@#Cortical thickness reduction in the left entorhinal, superior temporal, insular, rostral middle frontal, precentral, superior frontal, and supramarginal regions, and right supramarginal, precentral, insular, postcentral, and posterior cingulate regions was observed in the SCI compared to the NC group. Cortical thickness in these regions correlated with scores of constructional praxis, word list memory, word list recall, constructional recall, trail making test A, and verbal fluency under the CERAD protocol. Significantly decreased gyrification was observed in the left lingual gyrus of the SCI group. In addition, gyrification of this region was positively associated with scores of constructional praxis. @*Conclusion@#Our results may provide an additional reference to the notion that SCI may be associated with future cognitive impairment. This study may help clinicians to assess individuals with SCI who may progress to mild cognitive impairment and Alzheimer’s dementia.

Effect of Methylene Blue-mediated Photodynamic Therapy on Wild-type and Ciprofloxacin-resistant Mycobacterium smegmatis

Tuberculosis (TB) patients are normally treated with a combination of antibiotics. However, with improper or incomplete treatment of antibiotics, the disease may progress to multidrug-resistant TB (MDR-TB). The treatment of MDR-TB is very costly and inefficient. Therefore, there is a great demand of new therapeutic approaches for MDR-TB such as photodynamic therapy. In this study, we tried to optimize the conditions for photodynamic inactivation of TB using methylene blue as a photosensitizer. Different combinations of methylene blue concentrations and light doses were tested for their photodynamic effects to A549 cells or Mycobacterium smegmatis (M. smegmatis). We also tested the effect of photodynamic therapy on ciprofloxacin-resistant M. smegmatis. Methylene blue treatment alone did not affect the survival rates of A549 cells or bacteria up to 5 µg/ml. When the A549 and M. smegmatis cells treated with methylene blue were irradiated with laser light (wavelength, 630 nm), photodynamic inactivation of cells was increased in methylene blue concentration- and light dose-dependent manners. Interestingly, the ciprofloxacin-resistant M. smegmatis exhibited higher level of susceptibility to methylene blue-mediated photodynamic inactivation. This study suggests that photodynamic therapy at 3.6 J/cm2 in the presence of 5 µg/ml methylene blue may be an appropriate range for therapy due to the high bactericidal activity against high level of ciprofloxacin-resistant M. smegmatis and the low damaging effect to mammalian cells. This study demonstrates that photodynamic therapy could be a potential alternative for MDR-TB treatment.

Genetic Classification and Antimicrobial Resistance of Ureaplasma urealyticum Isolated from Urine

Recently, polymerase chain reaction (PCR)-based methods have been used to reclassify Ureaplasma urealyticum into two independent species (spp.), designating U. parvum and U. urealyticum. In the current study, we aim to reclassify U. urealyticum and to analyze the correlation between the presence of a genetic marker and an antibiotic resistance of U. urealyticum. Susceptibility test against tetracycline, levofloxain or moxifloxacin was performed by broth microdilution method. The presence of tet(M) gene and the mutations of quinolone resistance-determining regions (QRDRs) were analyzed by PCR and sequencing. Among fourteen Ureaplasma isolates, three were identified as U. parvum and eleven were identified as U. urealyticum, and this is first report showing that two independent spp. of U. urealyticum isolated from Korean are present. The minimum inhibitory concentration (MIC) ranges for Ureaplasma isolates were as follows: tetracycline 0.25~128 microg/ml, levofloxacin 1~8 microg/ml, and moxifloxacin 0.5~4 microg/ml. The tet(M) determinant was found in 3 among 14 Ureaplasma isolates with tetracycline MIC of >16 microg/ml, suggesting that the presence of the tet(M) determinant is associated with tetracycline resistance. Mutations of gyrA, gyrB, parC, and parE genes in the QRDRs were found in 3 among 14 Ureaplasma isolates, exhibiting only parE gene mutation is associated with fluoroquinolone resistance.