Exploitation of dihydroorotate dehydrogenase (DHODH) and p53 activation as therapeutic targets: A case study in polypharmacology

The tenovins are a frequently studied class of compounds capable of inhibiting sirtuin activity, which is thought to result in increased acetylation and protection of the tumor suppressor p53 from degradation. However, as we and other laboratories have shown previously, certain tenovins are also capable of inhibiting autophagic flux, demonstrating the ability of these compounds to engage with more than one target. In this study, we present two additional mechanisms by which tenovins are able to activate p53 and kill tumor cells in culture. These mechanisms are the inhibition of a key enzyme of the de novo pyrimidine synthesis pathway, dihydroorotate dehydrogenase (DHODH), and the blockage of uridine transport into cells. These findings hold a 3-fold significance: first, we demonstrate that tenovins, and perhaps other compounds that activate p53, may activate p53 by more than one mechanism; second, that work previously conducted with certain tenovins as SirT1 inhibitors should additionally be viewed through the lens of DHODH inhibition as this is a major contributor to the mechanism of action of the most widely used tenovins; and finally, that small changes in the structure of a small molecule can lead to a dramatic change in the target profile of the molecule even when the phenotypic readout remains static.     

Autofluorescence and Ultrastructure in the Myxomycete Diachea leucopodia (Physarales)

Autofluorescence is reported for the first time in Myxomycete fruiting bodies. Ultrastructure of stalked sporangia of Diachea leucopodia (Didymiaceae, Physarales) was studied using scanning and transmission electron microscopy, energy-dispersive X-ray microanalysis, and fluorescence microscopy. External and internal properties of the peridium that surround the spores and capillitium exhibit autofluorescence. The stalk is composed of calcareous granules and energy-dispersive X-ray microanalysis demonstrates that the elemental composition of the peridium, capillitium, and stalk has varying concentrations of calcium.     

Gangrenous Cutaneous Mucormycosis Caused by Rhizopus oryzae: A Case Report and Review of Primary Cutaneous Mucormycosis in China Over Past 20 Years

Cutaneous mucormycosis is a rare opportunistic infection caused by zygomycetes that can be rapidly fatal if unrecognized. We describe the clinical, histopathological, fungal and molecular features of a case of gangrenous cutaneous mucormycosis. The patient presented with great necrosis on his right forearm at the site of detained intravenous cannula needle. He had type II diabetes and chronic renal insufficiency. KOH mount of black eschar showed many broad, aseptate fungal hyphae with right-angle branching. PAS staining of the tissue sample revealed similar broad hyphae in the dermis and cutis. Fungal culture and ITS sequence analysis identified this fungus as Rhizopus oryzae. As no organ involvement was detected, the patient was diagnosed with primary cutaneous mucormycosis. Considering the poor state of the patient, complete excision of the infectious tissue was performed without skin graft instead of amputation. At the same time, intravenous liposomal amphotericin B was given, starting from a small dosage and increased to a total dosage amount of 5.45 g. The wound recovered well with granulation. We emphasize that early recognition and prompt therapy including the control of the primary diseases were important. In this article, we also reviewed the features of primary cutaneous mucormycosis reported in China over the last 20 years.     

Candidemia by Species of the Candida parapsilosis Complex in Children’s Hospital: Prevalence, Biofilm Production and Antifungal Susceptibility

Opportunistic infections are an increasingly common problem in hospitals, and the yeast Candida parapsilosis has emerged as an important nosocomial pathogen. The aims of this study were to determine and compare (i) the prevalence rate among C. parapsilosis complex organisms isolated from blood in a public children’s hospital in São Paulo state, (ii) the ability of the complex C. parapsilosis species identified to produce biofilm and (iii) the antifungal susceptibility profiles. Forty-nine (49) specimens of isolated blood yeast were analyzed, previously identified as C. parapsilosis by conventional methods. After the molecular analysis, the isolates were characterized as C. parapsilosis sensu stricto (83.7 %), C. orthopsilosis (10.2 %) and C. metapsilosis (6.1 %). All species were able to form biofilm. The species with the highest biofilm production was C. parapsilosis sensu stricto, followed by C. orthopsilosis and further by C. metapsilosis. All of the strains have demonstrated similar susceptibility to fluconazole, caspofungin, voriconazole, cetoconazole and 5-flucytosine. Only one strain of C. parapsilosis was resistant to amphotericin B. Regarding itraconazole, 66.6 and 43.9 % isolates of C. metapsilosis and C. parapsilosis, respectively, have demonstrated to be susceptible dose-dependent, with one isolate of the latter species resistant to the drug. Candida parapsilosis sensu stricto has demonstrated to be the less susceptible, mainly to amphotericin B, caspofungin and “azoles” such as fluconazole. Therefore, C. metapsilosis and C. orthopsilosis are still involved in a restricted number of infections, but these data have become essential for there are very few studies of these species in Latin America.     

Oxidative damage in relation to a female plumage badge: evidence for signalling costs

Badges of status may be controlled by costs derived from increased aggression from dominant individuals. This cost could be translated into elevated metabolic levels and a concomitant disruption of oxidative balance. Some females in Iberian pied flycatcher Ficedula hypoleuca populations exhibit a white forehead patch similar to that exhibited by all males in this species, functioning in aggressive interactions between females when competing for breeding sites. To test if social stress imposes costs on signalling, we painted white patches on females without natural patches (NP) and compared them with females with natural control (NU). We also over-painted the natural patch in other females (FP) and compared to females with control natural patches (FU). We obtained for the whole sample of females data on reproductive investment, morphology and oxidative damage measured by blood malondialdehydes (MDA), and in a subsample of females variables related to parental care during incubation and the early nestling stage. FP and FU did not differ significantly in any variable which negates an effect of paint itself. However, NP females showed significant higher levels of MDA than NU females when controlling for breeding success for the whole sample, and for female incubation attendance for the parental care subsample. When including the four treatments, there was a significant interaction between the paint treatment and the presence/absence of badges before the experiment when controlling for the significant negative effect of incubation attendance on MDA. Addition of a badge to females without one leads to increased oxidative damage possibly mediated by social control. Badges of status in female pied flycatchers may operate as badges of oxidative status.     

Constitutively active rhodopsin mutants causing night blindness are effectively phosphorylated by GRKs but differ in arrestin-1 binding

The effects of activating mutations associated with night blindness on the stoichiometry of rhodopsin interactions with G protein-coupled receptor kinase 1 (GRK1) and arrestin-1 have not been reported. Here we show that the monomeric form of WT rhodopsin and its constitutively active mutants M257Y, G90D, and T94I, reconstituted into HDL particles are effectively phosphorylated by GRK1, as well as two more ubiquitously expressed subtypes, GRK2 and GRK5. All versions of arrestin-1 tested (WT, pre-activated, and constitutively monomeric mutants) bind to monomeric rhodopsin and show the same selectivity for different functional forms of rhodopsin as in native disc membranes. Rhodopsin phosphorylation by GRK1 and GRK2 promotes arrestin-1 binding to a comparable extent, whereas similar phosphorylation by GRK5 is less effective, suggesting that not all phosphorylation sites on rhodopsin are equivalent in promoting arrestin-1 binding. The binding of WT arrestin-1 to phospho-opsin is comparable to the binding to its preferred target, P-Rh*, suggesting that in photoreceptors arrestin-1 only dissociates after opsin regeneration with 11-cis-retinal, which converts phospho-opsin into inactive phospho-rhodopsin that has lower affinity for arrestin-1. Reduced binding of arrestin-1 to the phospho-opsin form of G90D mutant likely contributes to night blindness caused by this mutation in humans.     

Point-of-care assays for tuberculosis: Role of nanotechnology/microfluidics

Tuberculosis (TB) remains one of the most devastating infectious diseases and its eradication is still unattainable given the limitations of current technologies for diagnosis, treatment and prevention. The World Health Organization's goal to eliminate TB globally by 2050 remains an ongoing challenge as delayed diagnosis and misdiagnosis of TB continue to fuel the worldwide epidemic. Despite considerable improvements in diagnostics for the last few decades, a simple and effective point-of-care TB diagnostic test is yet not available. Here, we review the current assays used for TB diagnosis, and highlight the recent advances in nanotechnology and microfluidics that potentially enable new approaches for TB diagnosis in resource-constrained settings.     

Influence of Toxoplasma gondii Acute Infection on Cholinesterase Activities of Wistar Rats

Several studies have shown the mechanisms and importance of immune responses against Toxoplasma gondii infection and the notable role of cholinesterases in inflammatory reactions. However, the association between those factors has not yet been investigated. Therefore, the aim of this study was to evaluate the acetylcholinesterase (AChE) activity in blood and lymphocytes and the activity of butyrylcholinesterase (BChE) in serum of rats experimentally infected with T. gondii during the acute phase of infection. For that, an in vivo study was performed with evaluations of AChE and BChE activities on days 5 and 10 post-infection (PI). The activity of AChE in blood was increased on day 5 PI, while in lymphocytes its activity was enhanced on days 5 and 10 PI (P<0.05). No significant difference was observed between groups regarding to the activity of BChE in serum. A positive (P<0.01) correlation was observed between AChE activity and number of lymphocytes. The role of AChE as an inflammatory marker is well known in different pathologies; thus, our results lead to the hypothesis that AChE has an important role in modulation of early immune responses against T. gondii infection.