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A Smart Setup for Craniospinal Irradiation
Peterson, Jennifer L.,Vallow, Laura A.,Kim, Siyong,Casale, Henry E.,Tzou, Katherine S. Korean Society of Medical Physics 2013 의학물리 Vol.24 No.4
Our purpose is to present a novel technique for delivering craniospinal irradiation in the supine position using a perfect match, field-in-field (FIF) intrafractional feathering, and simple forward-optimization technique. To achieve this purpose, computed tomography simulation was performed with patients in the supine position. Half-beam, blocked, opposed, lateral, cranial fields with a collimator rotation were matched to the divergence of the superior border of an upper-spinal field. Fixed field parameters were used, and the isocenter of the upper-spinal field was placed at the same source-to-axis distance (SAD), 20 cm inferior to the cranial isocenter. For a lower-spinal field, the isocenter was placed 40 cm inferior to the cranial isocenter at a constant SAD. Both gantry and couch rotations for the lower-spinal field were used to achieve perfect divergence match with the inferior border of the upper-spinal field. A FIF technique was used to feather the craniospinal and spinal-spinal junction daily by varying the match line over 2 cm. The dose throughout the target volume was modulated using the FIF simple forward optimization technique to obtain homogenous coverage. Daily, image-guided therapy was used to assure and verify the setup. This supine-position, perfect match craniospinal irradiation technique with FIF intrafractional feathering and dose modulation provides a simple and safe way to deliver treatment while minimizing dose inhomogeneity.
Flow Cytometric Analysis of Human Lysozyme Production in Recombinant Saccharomyces cerevisiae
Peterson Marvin S.,Kim Myoung-Dong,Han Ki-Cheol,Kim Ji-Hyun,Seo Jin-Ho The Korean Society for Biotechnology and Bioengine 2002 Biotechnology and Bioprocess Engineering Vol.7 No.1
Flow cytometric techniques were used to investigate cell size, protein content and cell cycle behavior of recombinant Saccharomyces cerevisiae strains producing human lysozyme (HLZ). Two different signal sequences, the native yeast $MF\alpha1$ signal sequence and the rat $\alpha-amylase$ signal sequence, were used for secretion of HLZ. The strain containing the rat $\alpha-amylase$ signal sequence showed a higher level of internal lysozyme and lower specific growth rates. Flow cytometric analysis of the total protein content and cell size showed the strain harboring the native yeast signal sequence had a higher total protein content than the strain containing the rat $\alpha-amylase$ signal sequence. Cell cycle analysis indicated that the two lysozyme producing recombinant strains had an increased number of cells in the $G_2+M$ phase of the yeast cell cycle compared with the host strain SEY2102.
Multimechanophore Graft Polymers: Mechanochemical Reactions at Backbone-Arm Junctions
Peterson, Gregory I.,Lee, Jaeho,Choi, Tae-Lim American Chemical Society 2019 Macromolecules Vol.52 No.24
<P>Typical multimechanophore polymers (MMPs) are comprised of numerous mechanophores (force-responsive moieties) distributed throughout the backbone of linear polymers. We have developed a new MMP design based on graft polymers with mechanophores linking each arm to the backbone. By utilizing maleimide-anthracene cycloadducts, polymeric species containing anthracene were released from the parent polymer, enabling facile quantification of mechanophore activation. With pulsed ultrasound experiments, we observed that mechanophore activation was dependent on the arm length (a faster rate with longer arms), and we observed that 85% of the polystyrene (PS) arms underwent scission (64% specifically at the mechanophore site) for a graft polymer with 23 kDa arms. Solid-state activation was also investigated with hand-grinding experiments. Fast reactions were observed, with up to 96% of PS arms undergoing scission and 70-75% of mechanophores being activated, for all arm lengths studied. Multimechanophore graft polymers provide important insight into the distribution of forces in topologically complex polymers and may enable the development of new mechanoresponsive materials.</P> [FIG OMISSION]</BR>
Peterson-Houle, Georgia M.,AbdelFattah, Magda R.,Padilla, Mariela,Enciso, Reyes The Korean Dental Society of Anesthsiology 2021 Journal of Dental Anesthesia and Pain Medicine Vol.21 No.5
Background: Trigeminal neuralgia (TN) is characterized by brief, unilateral, sharp, stabbing, and shooting pain of the fifth cranial nerve. The objective of this systematic review with meta-analysis was to determine the effect of medications compared to placebo in adult patients with TN. Methods: Review authors identified randomized placebo-controlled trials (RCTs) from PubMed, Web of Science, Cochrane, and EMBASE up to February 2021. We assessed the inclusion and exclusion criteria as well as the risk of bias of the studies based on the Cochrane Handbook. A total of 324 unduplicated references were scanned independently and reduced to eight relevant RCTs, with 89 patients included. Medications investigated included oral carbamazepine, subcutaneous sumatriptan, lidocaine (intranasal, 8% spray on the oral mucosa or intravenous), buprenorphine (ganglionic local opioid analgesia), and oral Nav1.7, a selective sodium channel blocker. Results: Meta-analyses showed that overall patients receiving lidocaine reported a significantly lower post-treatment intensity of pain -3.8 points on a 0-10 scale (95% Cl = -4.653 to -2.873; P < 0.001). Patients who received lidocaine were 8.62 times more likely to have pain improvement than patients on placebo (P < 0.001). In one RCT, patients receiving oral carbamazepine showed a significant improvement in pain intensity of -32% compared to the placebo (P < 0.001). In one trial, patients receiving 3 mg subcutaneous sumatriptan had a significantly lower intensity of pain on average -6.1 points on a scale of 0-10 compared to placebo (P < 0.001) and a significant improvement in pain intensity of -75% compared to the improvement in the placebo group (P < 0.001). Patients who received subcutaneous sumatriptan were 10 times more likely to have pain improvement than those who received placebo (P = 0.001) in one study. Due to the unclear/high risk of bias and small sample size, the quality of the evidence for lidocaine in the treatment of TN was low. Conclusion: Further studies are needed for carbamazepine, sumatriptan, buprenorphine, and oral Nav1.7 sodium channel blockers, as only one study reported outcomes.
Peterson, Gregory I.,Bang, Ki-Taek,Choi, Tae-Lim American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.27
<P>New polyphenylene-based dendronized polymers (denpols), exhibiting extended and rigid conformations, were prepared using ring-opening metathesis polymerization (ROMP). Their mechanochemical degradation was explored in ultrasound-induced elongational flow fields. Degradation rate constants were obtained for polyphenylene-based denpols, of varying generation, across a degree of polymerization (DP) range of ∼100-600. In general, it was found that larger side chains led to increased degradation rates and that the rate enhancement was proportional to the natural log of persistence length (Ln(<I>l</I><SUB>p</SUB>)) or the square root of monomer molecular weight (<I>M</I><SUB>mon</SUB><SUP>0.5</SUP>). These relationships led to the generation of “master curves” in which the rate constant trends for each polymer series converged, enabling accurate prediction of degradation rate constants for related polymers bearing long alkyl chains or ester-type dendrons. Furthermore, we observed evidence for, and used computational modeling to support, polymer chains undergoing multiple scissions during a single elongation event, leading to faster degradation of daughter fragments that come from parent polymers with large side chains.</P> [FIG OMISSION]</BR>