Citations

Background and purposeIntensity‐modulated proton therapy (IMPT) is highly sensitive to range uncertainties and uncertainties caused by setup variation. The conventional inverse treatment planning of IMPT based on the planning target volume (PTV) is not often sufficient to ensure robustness of treatment plans. We applied a probabilistic framework (chance‐constrained optimization) in IMPT planning to hedge against the influence of uncertainties.Material and methodsWe retrospectively selected one patient with lung cancer, one patient with head and neck (H&N) cancer, and one with prostate cancer for this analysis. Using their original images and prescriptions, we created new IMPT plans using two methods: (1) a robust chance‐constrained treatment planning method with the clinical target volume (CTV) as the target; (2) the margin‐based method with PTV as the target, which was solved by commercial software, CPLEX, using linear programming. For the first method, we reformulated the model into a tractable mixed‐integer programming problem and sped up the calculation using Benders decomposition. The dose‐volume histograms (DVHs) from the nominal and perturbed dose distributions were used to assess and compare plan quality. DVHs for all uncertain scenarios along with the nominal DVH were plotted. The width of the “bands” of DVHs was used to quantify the plan sensitivity to uncertainty. The newly developed Benders decomposition method was compared with a commercial solution to demonstrate its computational efficiency. The trade‐off between nominal plan quality and plan robustness was investigated.ResultsOur chance‐constrained model outperformed the PTV method in terms of tumor coverage, tumor dose homogeneity, and plan robustness. Our model was shown to produce IMPT plans to meet the dose‐volume constraints of organs at risk (OARs) and had better sparing of OARs than the PTV method in the three clinical cases included in this study. The chance‐constrained model provided a flexible tool for users to balance between plan robustness and plan quality. In addition, our in‐house developed method was found to be much faster than the commercial solution.ConclusionWith explicit control of plan robustness, the chance‐constrained robust optimization model generated superior IMPT plans compared to the PTV‐based method.

Granulomatosis with polyangiitis (Wegener's) is a rare autoimmune neutrophil-mediated vasculitis that can cause renal disease and mucosal manifestations. Antineutrophil cytoplasmic antibodies (ANCA) are present in many patients, vary in level over time, and induce neutrophil activation through engagement with Fc receptors (FcRs). Given roles for FcRs in ANCA-mediated neutrophil activation and IgA antibodies in mucosal immunity, we hypothesized that FcR genetics and previously unappreciated IgA ANCA affect clinical presentation. We assembled a total of 673 patients and 413 controls from two multicenter cohorts, performed ELISA and immunofluorescence assays to determine IgA and IgG ANCA positivity, and used Illumina, TaqMan, or Pyrosequencing to genotype eight haplotype-tagging SNPs in the IgA FcR ( FCAR ) and to determine NA1/NA2 genotype of FCGR3B, the most prevalent neutrophil IgG FcR. We evaluated neutrophil activation by measuring degranulation marker CD11b with flow cytometry or neutrophil extracellcular trap formation with confocal microscopy. Functional polymorphisms in FCGR3B and FCAR differed between patient groups stratified by renal involvement. IgA ANCA were found in ∼30% of patients and were less common in patients with severe renal disease. Neutrophil stimulation by IgA or IgG ANCA led to degranulation and neutrophil extracellcular trap formation in a FcR allele-specific manner (IgA:FCAR P = 0.008; IgG:FCGR3B P = 0.003). When stimulated with IgA and IgG ANCA together, IgG ANCA induced neutrophil activation was reduced ( P = 0.0001). FcR genotypes, IgA ANCA, and IgG ANCA are potential prognostic and therapeutic targets for understanding the pathogenesis and presentation of granulomatosis with polyangiitis (Wegener's).

Background— The clinical profiles and outcomes of patients treated surgically for acute type B aortic dissection (ABAD) are often reported for those in small series or for those cared for at a single institution over a long time period, during which a continuous evolution in techniques has occurred. Accordingly, we sought to evaluate the clinical features and surgical results of patients enrolled in the International Registry of Acute Aortic Dissection by identifying primary factors that influenced surgical outcome and estimating average surgical mortality for ABAD in the current era. Methods and Results— A comprehensive analysis of 290 clinical variables and their relation to surgical outcomes for 82 patients who required surgery for ABAD (from a population of 1256 patients; mean±SD age, 60.6±15.0 years; 82.9% male) and who were enrolled in the International Registry of Acute Aortic Dissection was performed. The overall in-hospital mortality was 29.3%. Factors associated with increased surgical mortality based on univariate analysis were preoperative coma or altered consciousness, partial thrombosis of the false lumen, evidence of periaortic hematoma on diagnostic imaging, descending aortic diameter >6 cm, right ventricle dysfunction at surgery, and shorter time from the onset of symptoms to surgery. Factors associated with favorable outcomes included radiating pain, normotension at surgery (systolic blood pressure 100 to 149 mm Hg), and reduced hypothermic circulatory arrest time. The 2 independent predictors of surgical mortality were age >70 years (odds ratio, 4.32; 95% confidence interval, 1.30 to 14.34) and preoperative shock/hypotension (odds ratio, 6.05; 95% confidence interval, 1.12 to 32.49). Conclusions— The present study provides insights into current-day clinical profiles and surgical outcomes of ABAD. Knowledge about different preoperative clinical conditions may help surgeons in making treatment decisions among these high-risk patients.

ABSTRACT The initiation of reverse transcription and nucleocapsid assembly in hepatitis B virus (HBV) depends on the specific recognition of an RNA signal (the packaging signal, ε) on the pregenomic RNA (pgRNA) by the viral reverse transcriptase (RT). RT-ε interaction in the duck hepatitis B virus (DHBV) was recently shown to require the molecular chaperone complex, the heat shock protein 90 (Hsp90). However, the requirement for RT-ε interaction in the human HBV has remained unknown due to the inability to obtain a purified RT protein active in specific ε binding. We now report that Hsp90 is also required for HBV RT-ε interaction. Inhibition of Hsp90 led to diminished HBV pgRNA packaging into nucleocapsids in cells, which depends on RT-ε interaction. Furthermore, using truncated HBV RT proteins purified from bacteria and five purified Hsp90 chaperone factors, we have developed an in vitro RT-ε binding assay. Our results demonstrate that Hsp90, in a dynamic process that was dependent on ATP hydrolysis, facilitated RT-ε interaction in HBV, as in DHBV. Specific ε binding required sequences from both the amino-terminal terminal protein and the carboxy-terminal RT domain. Only the cognate HBV ε, but not the DHBV ε, could bind the HBV RT proteins. Furthermore, the internal bulge, but not the apical loop, of ε was required for RT binding. The establishment of a defined in vitro reconstitution system has now paved the way for future biochemical and structural studies to elucidate the mechanisms of RT-ε interaction and chaperone activation.

ABSTRACT Initiation of reverse transcription in hepadnaviruses (hepatitis B viruses) depends on the specific binding of an RNA signal (the packaging signal, ε) on the pregenomic RNA template by the viral reverse transcriptase (RT) and is primed by the RT itself (protein priming). We have previously shown that the RT-ε interaction and protein priming require the cellular heat shock protein, Hsp90. However, additional host factors required for these reactions remained to be identified. We now report that five cellular chaperone proteins, all known cofactors of Hsp90, were sufficient to reconstitute a duck hepatitis B virus RT active in ε binding and protein priming in vitro. Four proteins, Hsp90, Hsp70, Hsp40, and Hop, were required for reconstitution of RT activity, and the fifth protein, p23, further enhanced the kinetics of reconstitution. RT activation by the chaperone proteins is a dynamic process dependent on ATP hydrolysis and the Hsp90 ATPase activity. Thus, our results have defined a minimal complement of host factors necessary and sufficient for RT activation. Furthermore, this defined in vitro reconstitution system has now paved the way for future biochemical and structural studies to elucidate the mechanisms of RT activation and chaperone functions.