Specific substitutions in the echinocandin target Fks1p account for reduced susceptibility of rare laboratory and clinical Candida sp. isolates

An association between reduced susceptibility to echinocandins and changes in the 1,3-beta-d-glucan synthase (GS) subunit Fks1p was investigated. Specific mutations in fks1 genes from Saccharomyces cerevisiae and Candida albicans mutants are described that are necessary and sufficient for reduced susceptibility to the echinocandin drug caspofungin. One group of amino acid changes in ScFks1p, ScFks2p, and CaFks1p defines a conserved region (Phe 641 to Asp 648 of CaFks1p) in the Fks1 family of proteins. The relationship between several of these fks1 mutations and the phenotype of reduced caspofungin susceptibility was confirmed using site-directed mutagenesis or integrative transformation. Glucan synthase activity from these mutants was less susceptible to caspofungin inhibition, and heterozygous and homozygous Cafks1 C. albicans mutants could be distinguished based on the shape of inhibition curves. The C. albicans mutants were less susceptible to caspofungin than wild-type strains in a murine model of disseminated candidiasis. Five Candida isolates with reduced susceptibility to caspofungin were recovered from three patients enrolled in a clinical trial. Four C. albicans strains showed amino acid changes at Ser 645 of CaFks1p, while a single Candida krusei isolate had a deduced R1361G substitution. The clinical C. albicans mutants were less susceptible to caspofungin in the disseminated candidiasis model, and GS inhibition profiles and DNA sequence analyses were consistent with a homozygous fks1 mutation. Our results indicate that substitutions in the Fks1p subunit of GS are sufficient to confer reduced susceptibility to echinocandins in S. cerevisiae and the pathogens C. albicans and C. krusei.     

Medical literature and vena cava filters: so far so weak

STUDY OBJECTIVE: With the development of percutaneous inferior vena cava (IVC) filters, IVC interruption has become a widely used procedure in patients with or at risk for venous thromboembolism. In an attempt at clarifying the indications for filter placement, a systematic literature review was undertaken. DESIGN: Bibliographic search and analysis. MEASUREMENTS AND RESULTS: A systematic MEDLINE search about vena cava filters produced a total of 568 references with abstracts between 1975 and 2000 inclusively. Each reference was analyzed according to predetermined criteria. Nearly two thirds (65.0%) of these publications were retrospective studies or case reports (33.3 and 31.7%, respectively), 12.9% were animal or in vitro studies, 7.4% were prospective studies, 6.7% were reviews, and 8.1% reported on miscellaneous related topics. Among the prospective studies, only 16 studies included > or = 100 patients, only 1 study was a randomized controlled trial (0.02% of 568 references), and heterogeneity among series precluded any relevant comparison. In a similar search about heparin and venous thromboembolism, 47.4% of 531 references were randomized controlled trials. CONCLUSIONS: Until more relevant data become available, literature reviews about vena cava filters will remain narrative, and many if not most indications for filter placement will remain a matter of opinion.     

Small molecule schweinfurthins selectively inhibit cancer cell proliferation and mTOR/AKT signaling by interfering with trans-Golgi-network trafficking

Natural compound schweinfurthins are of considerable interest for novel therapy development because of their selective anti-proliferative activity against human cancer cells. We previously reported the isolation of highly active schweinfurthins E-H, and in the present study, mechanisms of the potent and selective anti-proliferation were investigated. We found that schweinfurthins preferentially inhibited the proliferation of PTEN deficient cancer cells by indirect inhibition of AKT phosphorylation. Mechanistically, schweinfurthins and their analogs arrested trans-Golgi-network trafficking, an intracellular vesicular trafficking system, resulting in the induction of endoplasmic reticulum stress and the suppression of both lipid raft-mediated PI3K activation and mTOR/RheB complex formation, which collectively led to an effective inhibition of mTOR/AKT signaling. The trans-Golgi-network traffic arresting effect of schweinfurthins was associated with their in vitro binding activity to oxysterol-binding proteins that are known to regulate intracellular vesicular trafficking. Moreover, schweinfurthins were found to be highly toxic toward PTEN-deficient B cell lymphoma cells, and displayed 2 orders of magnitude lower activity toward normal human peripheral blood mononuclear cells and primary fibroblasts in vitro. These results revealed a previously unrecognized role of schweinfurthins in regulating trans-Golgi-network trafficking, and linked mechanistically this cellular effect with mTOR/AKT signaling and with cancer cell survival and growth. Our findings suggest the schweinfurthin class of compounds as a novel approach to modulate oncogenic mTOR/AKT signaling for cancer treatment.     

Supratentorial pressures: Part II: Intracerebral pulse waves

Intracerebral pulse waves were recorded in cat and monkey while intracranial pressure (ICP) manipulations were performed. The intracerebral pulse waves appeared comparable to cerebrospinal fluid (CSF) pulsations. The wave forms were divided into multiple smaller waves, designated P₁ to P₄. The P₁ component was primarily of arterial origin and was accentuated by increasing ICP unrelated to increased venous pressure, most commonly from a mass lesion. Bilateral carotid occlusion resulted in decreased amplitude of P₇. Venous hypertension from jugular venous or sagittal sinus occlusion, on the other hand, accentuated waves P₂ and P₃ more than P₇. This is consistent with a Starling resistor model of the cerebral venous system in which mass lesions may compress low-pressure veins and accentuate the arterial pressure-dependent P₁ wave, whereas venous hypertension causes increased prominence of the later P₂ and P₃ waves.     

Bigger,Faster, Stronger,More Ethical

Consider four elite female runners who trained hard for a 1500‐meter race. Runner 1 took extra‐strength aspirin before the race. Runner 2 has a genetic condition that results in greater levels of testosterone in her body than the typical range for a woman. Runner 3 has been on a carefully scheduled regimen of the hormone erythropoietin (EPO), which has increased her red blood cell count. Runner 4 has a team of diet, sleep, and exercise experts who ensured that she coordinated the exactly right balance of carbs and protein with her rest and workouts. Which of them cheated? Thomas Murray's Good Sport: Why Our Games Matter—and How Doping Undermines Them does not answer this question, but it provides tools to figure it out, and it argues that trying to answer is important.     

Researching Children’s Adjustment in Stepfamilies: How is it Studied? What Do we Learn?

The probability that children whose parents have separated will become members of a stepfamily has increased considerably in the last decades. This situation has encouraged researchers to document the impact of this family transition on children’s adjustment. The present article examines empirical publications on this subject between 2000 and 2015. Screening and eligibility assessment based on inclusion and exclusion criteria yielded a final sample of 130 studies. The theoretical models used by the authors are described and discussed, with particular attention to how theories are relied upon in this field of research. Second, an examination of the methodology applied allowed us to take a critical look at the way children’s outcomes were examined. The studies’ main results were then analyzed so as to draw up a contemporary portrait of how stepfamily children adjust. Finally, an examination of the studies’ limitations and theoretical foundations points to avenues for future research.