RESUMO
Atom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT's capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.
RESUMO
Measuring biological samples by atom probe tomography (APT) in their natural environment, i.e. aqueous solution, would take this analytical method, which is currently well established for metals, semi-conductive materials and non-metals, to a new level. It would give information about the 3D chemical structure of biological systems, which could enable unprecedented insights into biological systems and processes, such as virus protein interactions. For this future aim, we present as a first essential step the APT analysis of pure water (Milli-Q) which is the main component of biological systems. After Cryo-preparation, nanometric water tips are field evaporated with assistance by short laser pulses. The obtained data sets of several tens of millions of atoms reveal a complex evaporation behavior. Understanding the field evaporation process of water is fundamental for the measurement of more complex biological systems. For the identification of the individual signals in the mass spectrum, DFT calculations were performed to prove the stability of the detected molecules.
RESUMO
PURPOSE: Approximately 10-15% of breast cancer patients treated by breast conserving surgery (BCS) and adjuvant radiotherapy (RT) will develop ipsilateral breast tumor recurrence (IBTR). International guidelines suggest total mastectomy as treatment of choice for IBTR following lumpectomy and RT. Nevertheless, there is evidence that second BCS might be equally sufficient. PATIENTS AND METHODS: Patients with IBTR diagnosed between 1990 and 2014 after BCS and RT were included (n = 170). 34.1% women underwent secondary BCS, whereas 65.9% were treated by mastectomy. We determined predictive factors for time to local progression (TTP), disease free survival (DFS), and overall survival (OS) comparing these two groups. RESULTS: Median follow-up after primary IBTR was 49 months (59 months for patients still alive at time of analysis). Five-year IBTR-free rate after secondary BCS was 77.6% (SD ± 6.1%) and 75.0% (SD ± 4.5%) for patients after mastectomy. Five-year DFS was 57.3% (SD ± 8.2%), and 61.9% (SD ± 5.5%), five-year OS was 84.7% (SD ± 5.8%), and 72.6% (SD ± 5.1%), respectively. Prior adjuvant systemic therapy, muscular invasion, and skin infiltration were independent significant risk factors for a shorter TTP. Additionally, lymphovascular infiltration (LVI) in the IBTR increased the risk for a shorter DFS. LVI, muscular invasion, and skin infiltration were identified as independent significant risk factors for a shorter OS. CONCLUSION: No significant difference in local control, DFS, and OS was seen between IBTR patients treated either by secondary BCS or mastectomy. Our data suggest that secondary BCS for IBTR patients after initial BCS and RT is feasible in selected patients.
