No abstract

Two frequently used tools to acquire high-resolution images of cells are scanning electron microscopy (SEM) and atomic force microscopy (AFM). The former provides a nanometer resolution view of cellular features rapidly and with high throughput, while the latter enables visualizing hydrated and living cells. In current practice, these images are viewed by eye to determine cellular status, e.g. activated versus resting. Automatic and quantitative data analysis is lacking. This work develops an algorithm of pattern recognition that works very effectively for AFM and SEM images. Using rat basophilic leukemia (RBL) cells, our approach creates a support vector machine (SVM) to automatically classify resting and activated cells. 10-fold cross-validation with cells that are known to be activated or resting gives a good estimate of the generalized classification results. The pattern recognition of AFM images achieves 100% accuracy, while SEM reaches 95.4% for our images as well as images published in prior literature. This outcome suggests that our methodology could become an important and frequently used tool for researchers utilizing AFM and SEM for structural characterization as well as determining cellular signaling status and function.

In herpesvirus replicating cells, host cell gene transcription is frequently down-regulated because important transcriptional apparatuses are appropriated by viral transcription factors. Here, we show a small peptide derived from the Kaposi’s sarcoma-associated herpesvirus transactivator (K-Rta) sequence, which attenuates cellular MYC expression, reduces cell proliferation, and selectively kills cancer cell lines in both tissue culture and a xenograft tumor mouse model. Mechanistically, the peptide functions as a decoy to block the recruitment of coactivator complexes consisting of Nuclear receptor coactivator 2 (NCOA2), p300, and SWI/SNF proteins to the MYC promoter in primary effusion lymphoma cells. Thiol(SH)-linked alkylation for the metabolic sequencing of RNA (SLAM seq) with target-transcriptional analyses further confirm that the viral peptide directly attenuates MYC and MYC-target gene expression. This study thus provides a unique tool to control MYC activation, which may be used as a therapeutic payload to treat MYC-dependent diseases such as cancers and autoimmune diseases.

In herpesvirus replicating cells, host cell gene transcription is frequently down-regulated because important transcriptional apparatuses are appropriated by viral transcription factors. Here, we identified a small peptide derived from the Kaposi's sarcoma-associated herpesvirus transactivator (K-Rta) sequence, which attenuates cellular c-MYC expression, reduces cell proliferation, and selectively kills cancer cell lines in both tissue culture and a xenograft tumor mouse model. Mechanistically, the peptide functions as a decoy to block the recruitment of coactivator complexes consisting of Nuclear receptor coactivator 2 (NCOA2), p300, and SWI/SNF proteins to the MYC promoter in primary effusion lymphoma cells. Thiol(SH)-linked alkylation for the metabolic sequencing of RNA (​SLAM seq) with target-transcriptional analyses further confirmed that the viral peptide directly attenuates MYC and MYC-target gene expression. This study thus provides a unique tool to control MYC activation, which may have significant potential as a therapeutic payload to treat MYC-dependent diseases such as cancers and autoimmune diseases.

Purpose: To quantitatively assess the impact of interplay effect associated with the intra‐and inter‐fraction prostate motion and the delivery of the scanning proton beam. Methods: A cohort of ten prostate patients with weekly verification CTs was treated by proton pencil beam scanning with bi‐lateral single field uniform dose modality. A typical field has 10–15 energy layers and 500–1000 spots. According to patient treatment logs, each layer delivery time was less than 1 second with average time to change layers of about 8 seconds. Real‐time intrafraction prostate motions were determined from a previously reported prospective study using the Calypso beacon transponder. The worst‐case‐scenario patient prostate motion was adopted in this study. The prostate motion and the beam delivering sequence were synchronized to demonstrate the interplay effect. Results: CTV coverage was altered due to intrafraction motion. In each individual fraction, the CTV D_99% can vary more than 10% relative to the initial plan. However, over the entire course of treatment the total dose degradation of D_99% had a mean of −1.5% and standard deviation of 1.2%. The large variation generally happens where one beam spot is significantly heavier weighted relative to the surrounding spots. The magnitude of deviation also depends on individual patient. The consideration of both intrafraction and interfraction motion further reduced the CTV coverage D_99%, with mean of ‐ 1.7% and standard deviation of 1.3%. The mean dose to the anterior rectal wall varied about 10% due to either intrafraction or interfraction motion. Conclusion: The intrafraction and interfraction prostate motion have comparable dosimetric impact. The dose over the course of treatment can reduce ∼2% for CTV coverage and increase about 10% for anterior rectal wall.