Antifungal activity of compounds targeting the Hsp90-calcineurin pathway against various mould species

Objectives Invasive mould infections are associated with a high mortality rate and the emergence of MDR moulds is of particular concern. Calcineurin and its chaperone, the heat shock protein 90 (Hsp90), represent an important pathway for fungal virulence that can be targeted at different levels. We investigated the antifungal activity of compounds directly or indirectly targeting the Hsp90-calcineurin axis against different mould species. Methods The in vitro antifungal activity of the anticalcineurin drug FK506 (tacrolimus), the Hsp90 inhibitor geldanamycin, the lysine deacetylase inhibitor trichostatin A and the Hsp70 inhibitor pifithrin-μ was assessed by the standard broth dilution method against 62 clinical isolates of Aspergillus spp. and non-Aspergillus moulds (Mucoromycotina, Fusarium spp., Scedosporium spp., Purpureocillium/Paecilomyces spp. and Scopulariopsis spp.) Results FK506 had variable antifungal activity against different Aspergillus spp. and was particularly active against Mucor spp. Geldanamycin had moderate antifungal activity against Fusarium spp. and Paecilomyces variotii. Importantly, trichostatin A had good activity against the triazole-resistant Aspergillus ustus and the amphotericin B-resistant Aspergillus terreus as well as the MDR Scedosporium prolificans. Moreover, trichostatin A exhibited synergistic interactions with caspofungin against A. ustus and with geldanamycin against Rhizopus spp. for which none of the other agents showed activity. Pifithrin-μ exhibited little antifungal activity. Conclusions Targeting the Hsp90-calcineurin axis at different levels resulted in distinct patterns of susceptibility among different fungal species. Lysine deacetylase inhibition may represent a promising novel antifungal strategy against emerging resistant mould

Quantum cosmology with big-brake singularity

We investigate a cosmological model with a big-brake singularity in the future: while the first time derivative of the scale factor goes to zero, its second time derivative tends to minus infinity. Although we also discuss the classical version of the model in some detail, our main interest lies in its quantization. We formulate the Wheeler-DeWitt equation and derive solutions describing wave packets. We show that all such solutions vanish in the region of the classical singularity, a behaviour which we interpret as singularity avoidance. We then discuss the same situation in loop quantum cosmology. While this leads to a different factor ordering, the singularity is there avoided, too.Comment: 24 pages, 7 figures, figures improved, references added, conceptual clarifications include

Vascular changes in diabetic retinopathy-a longitudinal study in the Nile rat.

Diabetic retinopathy is the most common microvascular complication of diabetes and is a major cause of blindness, but an understanding of the pathogenesis of the disease has been hampered by a lack of accurate animal models. Here, we explore the dynamics of retinal cellular changes in the Nile rat (Arvicanthis niloticus), a carbohydrate-sensitive model for type 2 diabetes. The early retinal changes in diabetic Nile rats included increased acellular capillaries and loss of pericytes that correlated linearly with the duration of diabetes. These vascular changes occurred in the presence of microglial infiltration but in the absence of retinal ganglion cell loss. After a prolonged duration of diabetes, the Nile rat also exhibits a spectrum of retinal lesions commonly seen in the human condition including vascular leakage, capillary non-perfusion, and neovascularization. Our longitudinal study documents a range and progression of retinal lesions in the diabetic Nile rat remarkably similar to those observed in human diabetic retinopathy, and suggests that this model will be valuable in identifying new therapeutic strategies

Clinical and Genomic Characterization of Recurrent Enterococcal Bloodstream Infection in Patients With Acute Leukemia

Background. Rates and risk factors for recurrent enterococcal bloodstream infection (R-EBSI) and whether the same genetic lineage causes index EBSI and R-EBSI are unknown in patients with acute leukemia (AL) receiving chemotherapy. Methods. Ninety-two AL patients with EBSI from 2010 to 2015 were included. Enterococcal bloodstream infection was defined by 31 positive blood cultures for Enterococcus faecium or Enterococcus faecalis and fever, hypotension, or chills. Clearance was defined by 31 negative cultures 324 hours after last positive culture and defervescence. Recurrent enterococcal bloodstream infection was defined by a positive blood culture for Enterococcus 324 hours after clearance. Categorical variables were reported as proportions and compared by the χ2 test. Continuous variables were summarized by median and interquartile range (IQR) and compared by the Wilcoxon-Mann-Whitney Test. P values \u3c.05 were considered significant. Whole-genome sequencing was performed on available paired BSI isolates from 7 patients. Results. Twenty-four patients (26%) had 31 episodes of R-EBSI. Median time to R-EBSI (IQR) was 26 (13–50) days. Patients with R-EBSI had significantly longer durations of fever and metronidazole exposure during their index EBSI. Thirty-nine percent of E. faecium R-EBSI isolates became daptomycin-nonsusceptible Enterococcus (DNSE) following daptomycin therapy for index EBSI. Whole-genome sequencing analysis confirmed high probability of genetic relatedness of index EBSI and R-EBSI isolates for 4/7 patients. Conclusions. Recurrent enterococcal bloodstream infection and DNSE are common in patients with AL and tend to occur within the first 30 days of index EBSI. Duration of fever and metronidazole exposure may be useful in determining risk for R-EBSI. Whole-genome sequencing analysis demonstrates that the same strain causes both EBSI and R-EBSI in some patients

Longitudinal diffusion tensor imaging and neuropsychological correlates in traumatic brain injury patients

Traumatic brain injury (TBI) often involves focal cortical injury and white matter (WM) damage that can be measured shortly after injury. Additionally, slowly evolving WM change can be observed but there is a paucity of research on the duration and spatial pattern of long-term changes several years post-injury. The current study utilized diffusion tensor imaging to identify regional WM changes in 12 TBI patients and nine healthy controls at three time points over a four year period. Neuropsychological testing was also administered to each participant at each time point. Results indicate that TBI patients exhibit longitudinal changes to WM indexed by reductions in fractional anisotropy (FA) in the corpus callosum, as well as FA increases in bilateral regions of the superior longitudinal fasciculus (SLF) and portions of the optic radiation (OR). FA changes appear to be driven by changes in radial (not axial) diffusivity, suggesting that observed longitudinal FA changes may be related to changes in myelin rather than to axons. Neuropsychological correlations indicate that regional FA values in the corpus callosum and sagittal stratum (SS) correlate with performance on finger tapping and visuomotor speed tasks (respectively) in TBI patients, and that longitudinal increases in FA in the SS, SLF, and OR correlate with improved performance on the visuomotor speed (SS) task as well as a derived measure of cognitive control (SLF, OR). The results of this study showing progressive WM deterioration for several years post-injury contribute to a growing literature supporting the hypothesis that TBI should be viewed not as an isolated incident but as a prolonged disease state. The observations of long-term neurological and functional improvement provide evidence that some ameliorative change may be occurring concurrently with progressive degeneration

Prospectus, February 17, 1999

https://spark.parkland.edu/prospectus_1999/1005/thumbnail.jp