Cheng, M.-F. | bioRxiv Science

bioRxiv2025

Tracking White Matter Changes After Stereotaxic Radiosurgery inMiniature Pigs Using structural MRI, DTI, and FDG-PET

Stereotaxic radiosurgery (SRS) non-invasively and precisely ablates brain tumors or glioma located in the location where is surgically inaccessible with the aid of three- dimensional coordination system. This technique can also treat functional or psychiatric disorders, yet its dosimetry and curative mechanism remain to be elucidated. In this study, a miniature pig model was utilized to verify the effect of stereotaxic radiosurgery on a white matter tract with various doses delivered by CyberKnife. As porcine brain bears high resemblance to that of human in size and structure, the potential irradiation- induced change in structures and metabolism was monitored by conventional tools in clinical, including anatomical magnetic resonance image (MRI), diffusion tensor image (DTI) and 18F-Fluoro-D-Glucose positron emission tomography (FDG-PET). The right internal capsule was selected as the surgical target, and a one-year longitudinal study was conducted with whole brain images obtained once per three months. The results indicate that a dose equal to or higher than 60 Gy led to a late-onset radionecrosis which took a period close to 180 d to develop edema and breakage in the blood-brain barrier. In the meanwhile, DTI indices and differential tractography further illustrate a dose- and distance-dependent white matter injury along the tract of internal capsule. In contrast, doses of 40 Gy and below did not result in any discernible harm to the brain structure, but a sustained local inhibition in brain metabolism was observed in some pigs. The modulatory effect of low dose radiation awaits a comprehensive assessment throughout the whole brain in combination with behavioral or cognitive tasks built on pigs. This study showing the dose- and time-dependent changes will improve the understanding of the SRS dosimetry on the white matter and help investigators to decide an optimal window for brain imaging or behavioral assessment to take place on patients.

neuroscience↗

bioRxiv2018

Bloodstream Infection with Extended-spectrum Beta-lactamase-producing Escherichia coli: the role of virulence genes

BackgroundVarious bacterial putative virulence factors are involved in the pathogenesis of bacterial infection. However, the effect of comorbidities or infection syndrome in the association of virulence factors and mortality remains inconclusive.\n\nMethodThis study addressed whether specific sequence type (ST) and virulence factors of extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) are associated with different outcomes in patients with bloodstream infection.121 adults from southern Taiwan with ESBL-producing E. coli bloodstream infections were enrolled during a 6-year period. Demographic data, including infection syndromes, underlying disease and outcomes, were collected. The virulence factors in isolates were analyzed by PCR and multilocus sequence typing.\n\nResultPositivity for the virulence genes iha, hlyD, sat, iut, fyu, malX, ompT, usp and traT was associated with ST131 positivity (P<0.05). Some ESBL-EC virulence genes associated with urinary tract infection (UTI) were revealed. Positivity for ST405 and the virulence genes iroN and iss was significantly associated with increased 30-day mortality (death within 30 days) on univariate analysis (P<0.05). Independent risk factors of 30-day mortality in bacteremic patients with UTI included underlying chronic liver disease and malignancy. ST131 was borderline associated with 30-day mortality. Independent risk factors associated with 30-day mortality among bacteremic patients without UTI included comorbidities and iroN positivity.\n\nConclusionIn bacteremic patients with UTI, and the ST131 clone was borderline associated with mortality. Positivity for the virulence gene iroN may be linked to mortality in bacteremic patients without UTI.

microbiology↗