Supercharging protein ions in native mass spectrometry using theta capillary nanoelectrospray ionization mass spectrometry and cyclic alkylcarbonates.

Theta nanoelectrospray ionization of protein ions formed from aqueous buffer solutions that are mixed with denaturing solutions containing cyclic alkylcarbonates (e.g., vinyl ethylene carbonate; VEC) results in a significant increase in the extent of ion charging compared to native mass spectrometry. For six proteins, the extent of ion charging can be significantly higher than that obtained using denaturing solutions and alternative native "supercharging" methods. In theta nanoelectrospray supercharging, the extent of charging scales with protein mass in agreement with an analytical scaling relationship for ions with elongated structures. Theta nanoelectrospray supercharging of non-covalent complexes from native solutions results in essentially the complete loss of protein-ligand and protein-protein interactions. Based on circular dichroism spectroscopy, VEC can effectively denature proteins in buffered solutions. These data provide evidence that enrichment of VEC in theta nanoelectrospray ionization generated droplets can denature proteins on the timescale of droplet desolvation and ion formation. This approach can be used to form highly charged protein ions from native solutions containing biological buffers, including some that are considered incompatible with native MS. Forming some protein ions in the highest reported charge states directly from native solutions is no longer a challenge in obtaining primary structural information using tandem mass spectrometry.

Treatment and outcomes of melanoma in Asia: Results from the National Cancer Centre Singapore.

BACKGROUND: Acral melanoma (AM) and mucosal melanoma (MM) make up more than half of melanomas in Asia but comprise only 5% of cases in Caucasians, where cutaneous melanoma (CM) predominates. AM and MM are thought to be genetically and biologically distinct from CM. We report the characteristics and outcomes of melanoma patients from the National Cancer Centre Singapore. METHODS: Case records of 210 patients treated between 2002 and 2014 were reviewed. RESULTS: Median follow-up was 2.5 years. CM, AM and MM made up of 37.6%, 33.8% and 16.2% of cases, respectively, with 6.2% each having ocular melanoma and unknown primary. Caucasians made up 16.2% of patients, accounting for 36.7% of CM but only 2.8 of AM and 2.9% of MM. Patients with MM (2.9% stage I, 14.7% stage IV) presented with higher American Joint Committee on Cancer (AJCC) stage than those with AM (16.9% stage I, 5.6% stage IV) or CM (24.1% stage I, 8.9% stage IV) (P = 0.01). Median overall survival (OS) was 5.7 years for all patients, and 1.0 year for metastatic disease. Considering stage I-III disease, multivariable Cox regression analysis demonstrated age ≥60 years and higher stage to be independent adverse prognostic factors for RFS and OS. Sentinel lymph node biopsy, undertaken for 56 stage I-III patients (25 AM, 31 CM) did not influence outcome. CONCLUSION: Our study reinforces the known unique clinicopathologic features of melanomas in Asians where AM and MM predominate. Age and stage remain the most critical prognostic factors across all subtypes.

Highly sensitive simple homodyne phase detector for ultrasonic pulse-echo measurements.

We have designed and built a modern versatile research-grade instrument for ultrasound pulse-echo probing of the elastic properties of a wide range of materials under laboratory conditions. The heart of the instrument lies in an AD8302 microchip: a gain and phase detector from Analog Devices, Inc. To construct the device, we have implemented a schematic that utilizes the homodyne principle for signal processing instead of the traditional superheterodyne approach. This design allows one to measure phase shifts with high precision and linearity over the entire range of 0°-360°. The system is simple in construction and usage; it makes ultrasound measurements easily accessible to a broad range of researchers. It was tested by measuring the temperature dependence of the ultrasound speed and attenuation in a KTa0.92Nb0.08O3 (KTN) single crystal at a frequency of ∼40 MHz. The tests were performed in the vicinity of the ferroelectric transitions where the large variations of the speed and attenuation demand a detector with outstanding characteristics. The described detector has a wide dynamic range and allows for measuring in a single run over the whole temperature range of the ferroelectric transitions, rather than just in limited intervals available previously. Moreover, due to the wide dynamic range of the gain measurements and high sensitivity this instrument was able to reveal previously unresolvable features associated with the development of the ferroelectric transitions of KTN crystals.

A Cyclic di-GMP-binding Adaptor Protein Interacts with Histidine Kinase to Regulate Two-component Signaling.

The bacterial messenger cyclic di-GMP (c-di-GMP) binds to a diverse range of effectors to exert its biological effect. Despite the fact that free-standing PilZ proteins are by far the most prevalent c-di-GMP effectors known to date, their physiological function and mechanism of action remain largely unknown. Here we report that the free-standing PilZ protein PA2799 from the opportunistic pathogen Pseudomonas aeruginosa interacts directly with the hybrid histidine kinase SagS. We show that PA2799 (named as HapZ: histidine kinase associated PilZ) binds directly to the phosphoreceiver (REC) domain of SagS, and that the SagS-HapZ interaction is further enhanced at elevated c-di-GMP concentration. We demonstrate that binding of HapZ to SagS inhibits the phosphotransfer between SagS and the downstream protein HptB in a c-di-GMP-dependent manner. In accordance with the role of SagS as a motile-sessile switch and biofilm growth factor, we show that HapZ impacts surface attachment and biofilm formation most likely by regulating the expression of a large number of genes. The observations suggest a previously unknown mechanism whereby c-di-GMP mediates two-component signaling through a PilZ adaptor protein.

Safety and efficacy of aflibercept in combination with fluorouracil, leucovorin and irinotecan in the treatment of Asian patients with metastatic colorectal cancer.

AIM: To evaluate the safety and efficacy of the combination therapy of fluorouracil, leucovorin and irinotecan (FOLFIRI) and aflibercept in Asian patients with metastatic colorectal cancer (mCRC), who had progressed after oxaliplatin-based chemotherapy. METHODS: This is a retrospective analysis of 19 mCRC patients who received FOLFIRI and aflibercept (4 mg/kg intravenously) every 2 weeks via a Named Patient Program (supported by Sanofi Aventis) in Singapore. Treatment was administered until disease progression or unacceptable toxicities. Kaplan-Meier method was used to estimate progression-free survival (PFS) and overall survival (OS). Efficacy and toxicities were summarized using descriptive statistics. Statistical analysis was performed using STATA 12.0 software. RESULTS: The majority (84%) of the patients were of chinese ethnicity. The median age was 59 years, with 63.2% of the patients having an Eastern Cooperative Oncology Group status of 1. Four patients (21.1%) achieved partial response and 8 patients (42.1%) achieved stable disease. After a median follow-up of 9.6 months [95% confidence interval (CI), 2.2-13.1 months], the median OS was 11.6 months (95% CI, 6.1 to not-estimable), and median PFS was 4.1 months (95% CI, 2.2-5.9). Majority of the toxicities were grade 1-2, and include leucopenia (84.2%), anemia (73.7%), liver enzyme elevation (68.4%) and fatigue (68.4%). The most frequently reported grade 3 toxicities were neutropenia and neutropenic complications (both 15.8%). All adverse events resolved with supportive management. CONCLUSION: The clinical benefit and safety profile of the combination of FOLFIRI/aflibercept in Asian patients with mCRC are consistent with that of Western population. FOLFIRI/aflibercept may be an appropriate therapeutic option in Asian patients with mCRC previously treated with an oxaliplatin-based regimen.