An Efficient and Scalable "Second Generation" Total Synthesis of the Marine Polyketide Limaol Endowed with Antiparasitic Activity.

The cluster of four skipped exo-methylene substituents on the "northern" wing of limaol renders this dinoflagellate-derived marine natural product unique in structural terms. This arguably non-thermodynamic array gains kinetic stability by virtue of populating local conformations which impede isomerization to a partly or fully conjugated polyene. This analysis suggested that the difficulties encountered during the late stages of our first total synthesis of this polyketide had not been caused by an overly fragile character of this unusual substructure; rather, an unfavorable steric microenvironment about the spirotricyclic core was identified as the likely cause. To remedy the issue, the protecting groups on this central fragment were changed; in effect, this amendment allowed all strategic and practical problems to be addressed. As a result, the overall yield over the longest linear sequence was multiplied by a factor of almost five and the material throughput increased more than eighty-fold per run. Key-to-success was a gold-catalyzed spirocyclization reaction; the reasons why a Brønsted acid cocatalyst is needed and the origin of the excellent levels of selectivity were delineated. The change of the protecting groups also allowed for much improved fragment coupling processes; most notably, the sequence of a substrate-controlled carbonyl addition reaction followed by Mitsunobu inversion that had originally been necessary to affix the southern tail to the core could be replaced by a reagent controlled asymmetric allylation. Finally, a much-improved route to the "northern" sector was established by leveraging the power of asymmetric hydrogenation of a 2-pyrone derivative. Limaol was found to combine appreciable antiparasitic activity with very modest cytotoxicity.

Hydrogenative Cycloisomerization and Sigmatropic Rearrangement Reactions of Cationic Ruthenium Carbenes Formed by Catalytic Alkyne gem-Hydrogenation.

gem-Hydrogenation of propargyl alcohol derivatives with [CpX Ru(MeCN)3 ]PF6 (CpX =substituted cyclopentadienyl) as catalysts affords cationic pianostool ruthenium carbene complexes which are so electrophilic that they attack a tethered olefin to furnish cyclopentene products; cyclopropanation or metathesis do not compete with this novel transformation. If the transient carbenes carry appropriate propargylic substituents, however, they engage in ([2,3]-sigmatropic) rearrangements to give enol esters (carbonates, carbamates, sulfonates) or alkenyl halides. Both pathways are unprecedented in the vast hydrogenation literature. The proposed mechanistic scenarios are in line with labeling experiments and spectroscopic data; most notably, PHIP NMR spectroscopy (PHIP=parahydrogen induced polarization) provides compelling evidence that the reactions are indeed triggered by highly unorthodox gem-hydrogenation events.

Total Synthesis of Limaol.

A nonthermodynamic array of four skipped methylene substituents on the hydrophobic tail renders limaol, a C40-polyketide of marine origin, unique in structural terms. This conspicuous segment was assembled by a two-directional approach and finally coupled to the polyether domain by an allyl/alkenyl Stille reaction under neutral conditions. The core region itself was prepared via a 3,3'-dibromo-BINOL-catalyzed asymmetric propargylation, a gold-catalyzed spirocyclization, and introduction of the southern sector via substrate-controlled allylation as the key steps.

The doctor's point of view: eye-tracking as an investigative tool in the extubation process in intensive care units. A pilot study.

BACKGROUND: Patient safety is a top priority in healthcare. Little is known about the visual behavior of professionals during high-risk procedures. The aim of this study was to assess feasibility, usability and safety of eye-tracking to analyze gaze patterns during the extubation process in the intensive care unit. METHODS: Eye-tracking was used in this observational study to analyze the extubation process in 22 participants. Independent variables were average fixation time, dwell time, fixation count, hit ratio and revisit count for eighteen areas of interest. Primary outcome was dwell time for all areas of interest. Secondary outcomes were average fixation time, fixation count and revisits. In subgroup analyses, experienced and non-experienced physicians were compared. RESULTS: The most important area of interest was the patient, as analyzed by dwell time. Fixation of other areas of interest varied significantly among participants. Only 54% checked ventilator respiratory rate, despite declaring it as important in questionnaires. Other neglected areas of interest included tidal volume (59%), peak pressure (63.6%), CO2 (63.6%), temperature (18.2%), blood pressure (59%) and heart rate (68%). Experienced physicians gazed more frequently and longer at the patient while spending less time on monitor and ventilator parameters. CONCLUSIONS: Eye-tracking can demonstrate that there is a mismatch between physicians' subjective evaluations and corresponding objective real-life measurements. Structured and standardized extubation processes should be performed to improve patient safety. In the immediate postextubation phase, long dwell time on the patient shows that clinical observation remains the most important cornerstone beyond monitoring devices.

Evaluating Patient Safety And Ease Of Use Of A Novel Connection-Assist Device For Peritoneal Dialysis.

INTRODUCTION: It is estimated that there are currently over 3 million patients receiving dialysis treatment worldwide. With effective pre-dialysis counselling, a majority of patients choose the home-based therapy peritoneal dialysis (PD) but only approximately 11% of prevalent dialysis patients use this modality. Connection-assist devices can overcome the challenges posed by decreased manual dexterity and/or visual acuity, and can allow more patients to be treated with home-based therapies. As part of the CE marking authorization, a connection device has been evaluated for safety and ease of use in a usability study. METHODS: Fifteen patients and nine carers volunteered in this study, ranging from 23 to 86 years in age and from 0.3 to 24 years in experience in the PD therapy. The operating cycle consisted of eight tasks, each having several handling steps. The data analysis focused on the task effectiveness and the subjects' subjective feedback from the NASA task load index (N-TLX) questionnaire and semi-structured interviews. RESULTS: Of 1248 handling steps performed in total, 38 use errors were observed and discussed with the subjects. This equates to 97% of all handling steps being performed safely and easily. In all six dimensions of the N-TLX, more than 50 percent of subjects rated the task load 50 points or less on the scale. Regarding the handling of the device, 13 of 15 of the patients and 8 of 9 of the carers gave positive feedback. DISCUSSION: Safety and ease of use was demonstrated by evaluating task effectiveness (97% SU), interviews and N-TLX. Additionally the study provided valuable individual user feedback, which will inform the final design of the system for PD. The majority of patients and carers gave positive feedback regarding use and handling of this connection device. Innovative connection devices in general promise to reduce the barriers to using this home-based dialysis treatment.

Enantioselective synthesis of gem-disubstituted N-Boc diazaheterocycles via decarboxylative asymmetric allylic alkylation.

An enantioselective synthesis of diverse N4-Boc-protected α,α-disubstituted piperazin-2-ones using the palladium-catalyzed decarboxylative allylic alkylation reaction has been achieved. Using a chiral Pd-catalyst derived from an electron deficient PHOX ligand, chiral piperazinones are synthesized in high yields and enantioselectivity. The chiral piperazinone products can be deprotected and reduced to valuable gem-disubstituted piperazines. This reaction is further extended to enable the enantioselective synthesis of α,α-disubstituted tetrahydropyrimidin-2-ones, which are hydrolyzed into corresponding chiral ß2,2-amino acids.

Automating Areas of Interest Analysis in Mobile Eye Tracking Experiments based on Machine Learning.

For an in-depth, AOI-based analysis of mobile eye tracking data, a preceding gaze assign-ment step is inevitable. Current solutions such as manual gaze mapping or marker-based approaches are tedious and not suitable for applications manipulating tangible objects. This makes mobile eye tracking studies with several hours of recording difficult to analyse quan-titatively. We introduce a new machine learning-based algorithm, the computational Gaze-Object Mapping (cGOM), that automatically maps gaze data onto respective AOIs. cGOM extends state-of-the-art object detection and segmentation by mask R-CNN with a gaze mapping feature. The new algorithm's performance is validated against a manual fixation-by-fixation mapping, which is considered as ground truth, in terms of true positive rate (TPR), true negative rate (TNR) and efficiency. Using only 72 training images with 264 labelled object representations, cGOM is able to reach a TPR of approx. 80% and a TNR of 85% compared to the manual mapping. The break-even point is reached at 2 hours of eye tracking recording for the total procedure, respectively 1 hour considering human working time only. Together with a real-time capability of the mapping process after completed train-ing, even hours of eye tracking recording can be evaluated efficiently. (Code and video examples have been made available at: https://gitlab.ethz.ch/pdz/cgom.git).

Role of cyclin D1 amplification and expression in vulvar carcinomas.

Cyclin D1 (CCND1) belongs to the family of D-type cyclins involved in cell cycle progression, transcriptional regulation, and cell migration. CCND1 was found to be amplified and overexpressed in a variety of cancers, including some vulvar carcinoma cell lines. To determine the relationship of CCND1 copy number changes and CCND1 protein expression with clinicopathologic features and prognosis, 183 vulvar carcinomas were analyzed on a tissue microarray. Amplification was observed in 32 (22.4%) vulvar cancer specimens and was statistically related to the presence of regional lymph node metastases (P < .001). Detectable CCND1 expression was found in 139 (83.2%) of vulvar carcinomas, and 76 (45.5%) exhibited a moderate or strong expression. Increased levels of CCND1 expression were significantly related to higher patient age (P = .013), positive pN category (P = .004), and negative human papillomavirus status (P < .001). Basaloid as well as verrucous, warty-type, and mixed vulvar carcinomas showed lower CCND1 expression levels than keratinizing or nonkeratinizing tumors (P < .001 and P = .032, respectively). Elevated CCND1 expression levels and amplification of the CCND1 gene were closely connected in the present analysis (P < .001). Patient prognosis was independent from CCND1 amplification status and expression level (P = .57 each). In conclusion, CCND1 is amplified and overexpressed in a substantial proportion of vulvar carcinomas and associated with the occurrence of locoregional lymph node metastases, especially in human papillomavirus-negative tumors.

Overexpression of carbonic anhydrase IX (CAIX) in vulvar cancer is associated with tumor progression and development of locoregional lymph node metastases.

Carbonic anhydrase IX (CAIX) is a strictly membranous expressed metalloenzyme involved in cell adhesion, pH homeostasis, and cancer progression. The protein is specifically overexpressed in a wide variety of malignant tumors. This study was designed to assess the role of CAIX in primary vulvar cancer. One hundred forty-two well-characterized primary vulvar carcinomas were analyzed on a tissue microarray (TMA). Three tissue cores were sampled from each tumor. CAIX expression was determined by immunohistochemistry, using a four-step scoring system. To determine CAIX expression in benign vulvar tissue, we constructed a TMA with 120 samples of normal mucosa and non-neoplastic diseases. CAIX expression was found in 77/135 (57%) of all assessable vulvar cancer specimens and 48 (35.5%) exhibited a moderate or strong expression. CAIX expression in vulvar carcinomas was significantly stronger compared to non-neoplastic vulvar tissue (p < 0.001). High levels of CAIX expression were related to pT stage (p < 0.01), tumor size (p < 0.01), depth of invasion (p < 0.05), as well as inguinal lymph node metastases (p < 0.05). There was also a trend towards shorter recurrence-free patient survival in CAIX-positive compared to CAIX-negative vulvar cancers. CAIX staining results in different tissue cores from the same tumor were homogeneous, raising the possibility of a hypoxia-independent expression. In conclusion, CAIX is overexpressed in the majority of vulvar carcinomas with relationships to advanced tumor stages and development of lymph node metastases. Our data support the potential therapeutic benefit of newly developed targeting antibodies in advanced vulvar cancer.

Gravitational stability of suspensions of attractive colloidal particles.

Colloidal suspensions are susceptible to gravitationally induced phase separation. This can be mitigated by the formation of a particle network caused by depletion attraction. The effectiveness of this network in supporting the buoyant weight of the suspension can be characterized by its compressional modulus. We measure the compressional modulus for emulsion networks induced by depletion attraction and present a model that quantitatively predicts their gravitational stability. We also determine the relationship between the strength of the depletion attraction and the magnitude of the compressional modulus.

Distance-dependent activation energies for hole injection from protonated 9-amino-6-chloro-2-methoxyacridine into duplex DNA.

The recent investigation of the apparently anomalous attenuation factor (beta > 1.5 A(-1)) for photoinduced hole injection into DNA duplexes modified by protonated 9-amino-6-chloro-2-methoxyacridine (X+) led to the conclusion that in addition to the electronic couplings, the activation energy must also be distance-dependent. In this communication we report the verification of this postulate by direct measurements of the activation energies for a series of (X+)-modified DNA duplexes which sample an appreciable range of donor-acceptor distances (approximately 4-11 A). The resulting changes in thermal activation energy can be explained within the framework of a distance-dependent reorganization energy.

Determination of bleeding risk using genetic markers in patients taking phenprocoumon.

BACKGROUND: In patients on oral anticoagulation with warfarin, genetic variations of the cytochrome P 450-CYP2C9 have recently been associated with very low warfarin requirements. Patients needing low doses had an increased risk for bleeding complications. In Germany, phenprocoumon (having a similar metabolic pathway) is the most commonly employed vitamin K antagonist. Treatment is usually monitored by general practitioners (GPs). OBJECTIVES: To determine whether CYP2C9 variant alleles can serve as risk markers in general-practice patients anticoagulated with phenprocoumon. METHODS: All adult anticoagulated patients in 12 teaching general practices and one university outpatient clinic were to be recruited. Blood samples were taken from 185 patients during routine anticoagulation controls and tested for CYP2C9 mutations. Subjects answered a questionnaire concerning bleeding complications, drug intolerance, and personal and family medical history. Phenprocoumon dosages required for stable anticoagulation were recorded. Odds ratios (OR) with 95% confidence intervals (CI) were calculated based on 2-way cross-tabulations and multivariate logistic regression models, t-tests used where appropriate. RESULTS: Bleeding was reported by 19% of the patients, 2.2% of whom had suffered life-threatening bleeding. CYP2C9 variants were carried by 26.3% of 179 patients tested (17.9% *1/*2, 7.8% *1/*3, 0.6% *2/*3). While presence of a *2 allele was not associated with an increased risk (OR 0.35, CI 0.10-1.24), carriers of the rare *3 alleles had a higher risk of bleeding (OR 3.10, CI 1.02-9.40). With regard to bleeding, carrying CYP2C9*3 was highly specific (94%), though sensitivity was low at 17%; post-test probability of bleeding was 40%. CONCLUSIONS: CYP2C9*3 variants are associated with an increased bleeding risk in patients anticoagulated with phenprocoumon. Screening can identify patients with a high risk of bleeding. Appropriate clinical consequences (restricted indication for anticoagulation, careful induction, adjustment of target INR, closer monitoring or self-testing of INR) as well as the cost-effectiveness of screening for variant CYP2C9 with regard to patient outcomes should be subject of further research.