Predictive Factors for Response to Adaptive Therapy in Thoracic Stereotactic Ablative Radiotherapy

PURPOSE/OBJECTIVE(S)

Online adaptive radiotherapy (ART) has been increasingly adopted for clinical use. However, ART for thoracic malignancies has lagged beyond its implementation for other primary cancers. Efforts are needed to identify optimal patients for ART by finding trends for changes in tumor position, shape, or proximity to OARs are needed. We hypothesized tumor size, histology, pre-RT SUV value, and intrathoracic location could influence how tumors change during cone beam computed tomography (CBCT)-based ART Stereotactic Ablative Radiotherapy (SAbR) for thoracic disease.

MATERIALS/METHODS

Data was collected from a prospective registry of patients who received CBCT-ART and SAbR for primary and secondary lung tumors. Dosimetry data was obtained from the simulation planning and the daily adaptive workflow. Central lung tumors were defined as those located within 2 cm of the bronchial tree. Plans were either delivered as per simulation or through the online adaptive workflow delivery (AD). Change in planning tumor volumes (PTV) were calculated between initial and final fractions (ΔPTV).

RESULTS

A total of 42 patients with a median age of 67 (range 17-90) and median 8.3 months follow up, treated between June 2021 and December 2022 were included. Most patients had NSCLC or presumed NSCLC (73.85%, 31/42), and most lesions were peripheral (61.9%, 26/42) versus central (31%, 13/42) or apical (7.1%, 3/42). Mean dose and median fractions were 52.5 Gy (SD 8.07) and 5 (range 3-5) while median initial (i) PTV was 31.75 cm3 (IQR 42.3 cm3). On average, ΔPTV decreased by 4.9% (SD 21) and volume shrunk by 5 cm3 (SD 14.5). AD improved per fraction PTV coverage and conformality while esophageal, cardiac, and spinal cord dose were significantly decreased (all p < 0.05), and most fractions were delivered with AD (73.4%, 138/188). AD was aborted most often for small iPTVs. ΔPTV grew >10% for two lesions though their iPTV were < 10 cm3. 12/42 ΔPTV were >10% smaller by the end of RT and corresponded to larger iPTVs. Age, lung primary, metastatic disease, smoking status, and tumor location were not predictive for >10% decrease in ΔPTV. Among 24 biopsy-proven NSCLC ΔPTV was >10% smaller in 6/12 patients (50%) with adenocarcinoma and only in 2/12 (16.7%) with SCC, although this was not significant on χ2 testing (p = 0.08). There were no differences in local, regional, distant failure or death comparing those with a ΔPTV of >10% vs <10% (all p > 0.1). Comparing pre-treatment PET SUV and tumor response, lower SUVs appear to be associated with more PTV shrinkage, with no significant PTV change plateauing at SUV 20. However, this analysis was limited by the number of patients with high SUV values.

CONCLUSION

CBCT-ART SAbR is associated with improved PTV coverage, target conformality, and reduced OAR dose. Large iPTV and adenocarcinomas were more likely to decrease >10%. High metabolic activity appeared predictive for a lack of significant ΔPTV. Further clinical and radiographic features should be explored to predict response to ART.

Towards Biology-Guided Radiotherapy Planning and Delivery on a Novel O-Ring PET-Linac Platform: Extended Beyond Bone and Lung Lesions

PURPOSE/OBJECTIVE(S)

Biology-guided radiotherapy (BgRT) with FDG signal collected via an on-board positron emission tomography (PET) system integrated in an O-ring gantry Linac was recently cleared by the FDA for lung and bone lesions. This study aims to determine if BgRT plans, guided via PET signal, are clinically acceptable for FDG-avid lesions in disease sites beyond bone and lung.

MATERIALS/METHODS

Ten patients previously treated for lesions in the liver, head and neck (HN), pancreas, renal and pelvic-abdominal lymph nodes were identified. Diagnostic PET/CT images of these treatment sites were first collected and processed/converted to mimic PET images that are acquired on PET-Linac and would be used to guide the delivery. For BgRT planning, the PTV was generated with 5 mm margin from GTV and a Biology Tracking Zone was generated including the anticipated full range of target motion. BgRT plans, guided by the emulated PET signal, were generated with 46Gy in 3 fractions for liver and 40Gy in 5 fractions for all other sites. BgRT plan deliverability was first assessed by evaluating the Activity Concentration (AC) and Normalized Target Signals (NTS) on converted PET images with the goal to meet NTS >2 (hard constraint) and AC >5kBq/ml (goal). BgRT plan quality was then evaluated with institutional guidelines on PTV coverage, OAR doses, conformity index (CI) and Heterogeneity index (HI).

RESULTS

BgRT plans were successfully generated for 11 target lesions among ten patients. The average diagnostic PET SUV, derived NTS and AC on converted PET images were 12.62, 9.33 and 12.10 kBq/ml, respectively. All images met the NTS constraints, and 8/11 plans met the AC goal for deliverability. All plans met the OAR hard constraints such as max dose on duodenum, small bowel, large bowel and spinal cord. Five of 11 plans had a limiting GI structure that resulted in an expected reduction in PTV coverage with an average PTV V100% = 77.9%, CI of 1.4, HI of 1.36 and max dose of 133.8%. The other 6 of 11 cases met the PTV V100% = 95%, had an average CI of 1.1, HI of 1.28 and Dmax of 127.67%. The estimated average time for BgRT delivery was 17 mins 25 secs. Although these plan parameters are deemed to be clinically acceptable, heterogeneity was detected inside the target region and suboptimal dose fall off was observed in some cases that may be caused by current implementation.

CONCLUSION

This preliminary study showed that BgRT plans were generated successfully with emulated PET images on 11 treatment sites covering HN, abdominal and pelvic regions. All plans met NTS constraints and 8 out of 11 met AC goals for deliverability. The plan quality of all BgRT plans were clinically acceptable based on institutional constraints. Further investigations are required to test more patients/sites for BgRT plan feasibility. Dosimetric benefit from margin reduction of BgRT target should also be investigated in future study.

Simulation-Omitted Replan with Cone Beam Computed Tomography based Adaptive Online Radiotherapy System - Transferring Adapted Plan to Non-Adaptive Ring Gantry Linear Accelerator for Image Guided Radiotherapy

PURPOSE/OBJECTIVE(S)

Artificial intelligence powered cone beam computed tomography (CBCT) based online adaptive radiotherapy (oART) system offers a streamlined and efficient process for daily ART as the default. In our prior work, we developed a workflow to utilize this oART system as simulation-omitted replan platform and treat the adapted plan on the oART system with image guided radiotherapy (IGRT) until next adaptation. However, the IGRT fractions will occupy the treatment slots of the machine. In this work, we aim to develop a semi-automatic workflow to allow the adapted plan to be treat on the non-adaptive ring gantry linear accelerator (non-ART Linac) and dedicate the oART system for adaptive treatments.

MATERIALS/METHODS

The oART system and the non-ART Linac were machine-matched to the same representative beam data. In the oART system, the initial plan is setup as 'adaptive' treatment and patients are only treated on the oART system for adaptive replan. The IGRT fractions are all treated on the non-ART Linac. An API script was developed to automatically (1) grab the adapted DICOM plan files from the secondary calculation system and write directly back to the database of the treatment management system (TMS), (2) change the DICOM tags to make the files compatible in the TMS system, (3) insert the kV-CBCT field to make the plan deliverable in the non-ART Linac. There are minimum remaining manual steps to setup the number of fractions to the intended number of IGRT fractions and to link plan to the prescription in TMS. We compare the required resources and the percentage of ART treatments on the oART system before and after the implementation of the proposed workflow to quantify the improvement of service.

RESULTS

The proposed workflow and automation eliminated the need to convert between IGRT/ART fractions in the Ethos system and reduced manual work by 25 minutes each adapted plan transfer. Table 1 summarizes the number of physics tasks and the percentage of ART fractions in oART system per month before and after the proposed workflow. This workflow reduced the physics IGRT/ART tasks from 107±31 to 65±21 tasks per month (p<0.05). Percentage of ART treatments on oART system increase from 30%±3% to 57%±13% (p<0.05). We also observed increased utilization of ART from 46% in the 1st month to 71% in the 6th month since it is easier to find a feasible time slot for the clinical team. The majority of the remaining IGRT on oART system are lung SBRT where the first fraction is not adapted due to being within a week of the simulation.

CONCLUSION

Leveraging CBCT based ART system as replan platform and non-ART Linac as IGRT platform is clinically feasible. This process significantly improved the turnaround time for replan, reduced the required resource and promotes the utilization of oART.

Intelligent Interactive Deformable Image Registration for Online Adaptive Radiotherapy

PURPOSE/OBJECTIVE(S)

The goal of this study is to streamline the time-consuming contouring process in online adaptive radiotherapy (ART) by utilizing a deep learning-based interactive deformable image registration (DIR) algorithm. The objective is to minimize manual review and editing of automatically generated initial contours of organs-at-risk (OARs) and targets, thereby improving the efficiency and effectiveness of the treatment process.

MATERIALS/METHODS

Our proposed method reforms the current DIR-based contour propagation method in clinical practice through the implementation of a deep learning-based interactive approach. The steps include: 1) generation of an initial deformable vector field (DVF) using a DL model, based on fixed and moving image pairs, resulting in the initial contours of OARs and targets; 2) clinician review/edit one the OAR/target contours as needed; 3) updated contour is sent to DL model to update the DVF and the remaining OARs/targets contours. Repeat this process until satisfactory contour qualities are achieved. We used the Open Access Series of Imaging Studies (OASIS) as the testbed, including 394 (train) and 20 (test) brain T1-weighted MRI scans, each containing 35 annotated organs. The U-Net architecture was employed to update the DVF from fixed/moving images, initial contours, and updated contours. We compared our approach to traditional manual editing without interaction and quantified the effort reduction using the added path length (APL) metric which is supposed to be proportional to the absolute time spent on the contour editing. We conducted paired t-test to show the significance. For comparison purpose, we assumed the clinicians edit the contours with the largest APL, i.e., the contours that require the most editing efforts.

RESULTS

The editing effort, as measured by APL, was reduced by 18.5% to 25.4% with a mean of 23.3%, median of 23.6%, and standard deviation of 1.9%. The significance of the results was confirmed with a p-value of 1.47e-24.

CONCLUSION

Our study demonstrates a significant reduction in editing effort, as measured by APL, compared to traditional manual contour editing. These results demonstrate the potential of our deep learning-based interactive approach to improve the efficiency and accuracy of the contouring process in clinical practice.

Dosimetric Analysis of CBCT-Based Weekly Online Adaptive Radiotherapy for Locally Advanced Non-Small Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

Anatomic and geometric changes are common during a radiotherapy course amongst patients receiving conventional fractionated radiotherapy for locally advanced non-small cell lung cancer (LA-NSCLC). These changes may cause significant deviation from initial reference plan resulting in over-treatment of normal tissue or under-coverage of the target. Cone-beam computed tomography (CBCT)-based online adaptive radiotherapy (ART) platforms allow for response to these changes and is being increasingly used in the clinic though less so for intrathoracic disease. We hypothesized weekly CBCT-ART would improve target coverage and decrease dose to organs at risk (OAR) in patients with LA-NSCLC.

MATERIALS/METHODS

Data was collected from a prospective registry of 23 LA-NSCLC patients treated to 60 Gy in 30 fractions with CBCT-ART between June 2021 and December 2022. For weekly ART (Wk-ART), online plan adaptation started on week two. The adapted plan was then used to treat patients with image guidance until the next ART. For comparison, doses were recalculated with the initial reference plan on the SCT with updated contours to derive non-adapted (non-ART) dosimetry for each week. The final dosimetric parameters were obtained by averaging weekly coverage (ITV, PTV) and critical OAR (Lung, esophagus, heart, spinal cord) doses for non-ART and weekly ART treatments respectively for each patient. Paired student t-test was performed to compare the dosimetric parameters between non-ART and Wk-ART.

RESULTS

We observed an average 29% ± 19% (median: 26%) reduction in ITV volume through the radiotherapy course, with 48% (11/23) of patients showing >30% reduction. Most significant volume reductions (16%) were observed between the third and fourth adaptation. Weekly ART showed significant (p<1×10-3) improvements in ITV and PTV coverage, and showed improved clinically relevant lung, esophageal, cardiac, and lung dosimetry (Table 1), especially in the later stages of treatment when the tumor showed significant shrinkage. The average time from contour review to quality assurance completed is 8.5±1.2 min.

CONCLUSION

CBCT-ART provides robust ART plan quality and efficient workflow. There are significant improvements in target coverage and OAR sparing in LA-NSCLC treated with weekly CBCT-ART and these are driven by the significant volume reduction of the ITV throughout treatment course.

Predicted Cardiac Toxicity in Daily Cone-Beam CT-Based Online Adaptive Stereotactic Partial Breast Irradiation with Decreased PTV Margins

PURPOSE/OBJECTIVE(S)

Partial breast irradiation (PBI) targets a smaller volume over less time compared to whole breast radiation, but the organ-at-risk (OAR) sparing allowed by its large (up to 1 cm) PTV can be improved. The heart is sensitive to low doses with conventional fractionation and NTCP models have been created for heart substructures. We hypothesized that daily online adaptive stereotactic PBI (A-SPBI) IMRT with 3-mm PTV improves dosimetry and predicted cardiac toxicity risk.

MATERIALS/METHODS

Patients treated with daily CBCT-based online A-SPBI IMRT were excluded if the minimum heart dose was <1 Gy. IMRT radiation plans with 3-mm PTV margins were recreated with 1-cm margins per the Florence APBI IMRT trial planning guideline. Dose statistics were converted to the equivalent doses in 2-Gy fractions (EQD2) using α/β = 3 for use in NTCP models and for comparison using paired t tests, with differences considered significant if p≤0.05.

RESULTS

The table details heart, left anterior descending artery (LAD), and left (LV) and right ventricle (RV) EQD2 statistics for 4 left-sided and 4 right-sided 3-mm PTV plans and their 1-cm PTV replans. For 2 patients with non-zero LV V5, 9-year excess cumulative risk of acute coronary event was <0.001% for both margin sizes. No plan reached thresholds for increased risk of non-cardiac death, major adverse cardiac event, or >10% decrease in LV ejection fraction.

CONCLUSION

Given the established relationship between low MHD and cardiac events, the significant decrease in MHD revealed in comparisons of 3-mm and 1-cm PTV A-SPBI plans of our first 8 patients is promising; we expect the forthcoming larger sample size to show significant differences in substructure doses. NTCP models created for non-IMRT breast plans and targets with higher heart exposure did not predict clinically-relevant differences in cardiac risk. NTCP model development for the low heart dose achieved with A-SPBI would define expected benefit in these patients; in their absence, daily adaptation should be considered in patients with unfavorable anatomy or cardiac risk factors.

Assessment of Cardiac Radiation Dose in the Co-60 Prone Based Stereotactic Partial Breast Irradiation (CP-sPBI) Using the Distance from the Heart to the Planning Treatment Volume as a Surrogate Marker

PURPOSE/OBJECTIVE(S)

Irradiation of the breast has shown to provide sharp dose gradients using Co-60 prone based stereotactic partial breast irradiation (CP-sPBI), a contemporary device for stereotactic radiotherapy for breast cancer (BC) for accelerated partial breast irradiation (APBI). In addition, the precise setup of CP-sPBI permits a small planning treatment volume (PTV) margin of 3 mm creating a greater distance from PTV to organs at risk. However, to date the factors that influence dose gradients and subsequent cardiac doses of ionizing radiation using CP-sPBI have not been well-studied. Here we evaluate distance of the heart to the lumpectomy PTV cavity and how this effects cardiac dose.

MATERIALS/METHODS

A retrospective database of 113 consecutive patients treated by CP-sPBI for APBI from March 2019 to February 2023 who were treated with 30 Gy in 5 fractions were queried for analysis. The minimum distance from the heart to the PTV (hP) was measured in either the axial or sagittal view. A group of 28 patient cases were randomly selected to achieve an even distribution of 28 cases with hP < 2.75 cm and hP ≥ 2.75 cm to compare cardiac toxicities based on hP. Descriptive analyses were performed to evaluate various cardiac dosimetric parameters based on laterality of BC and hP, using the student's t test.

RESULTS

The mean (range) hP was 4.58 cm (0.80-12.23) for all cases. The subgroup analyses of 28 patient cases with cardiac parameters showed the heart mean (range) dose of 1.20 Gy (0.01-2.11). The mean and max heart dose to the left-sided BC were similar to those to the right-sided BC (mean dose: 1.20 vs. 1.19 Gy; P = 0.97 and max dose: 10.47 vs. 5.66 Gy; P = 0.06). An inverse correlation between hP and mean heart dose was shown with the correlation coefficient of -0.81. Using a cutoff of 2.75 cm hP, the differences between hP < 2.75 and hP ≥ 2.75 cm for all cardiac dosimetric evaluations were all statistically significant, including mean (1.67 vs. 0.79 Gy; p<0.01) and maximal heart dose (14.48 vs. 4.11 Gy; p<0.01) CONCLUSION: CP-sPBI treatment delivery system was able to achieve acceptable clinically relevant heart dosimetric parameters when delivering 5 fraction APBI with a mean heart dose of 1.20 Gy for all locations of PTV cavity volume in the breast. Due to CP-sPBIs excellent dose fall-off characteristics, APBI using CP-SPBI showed clinically acceptable cardiac dosimetric parameters, particularly for PTVs located > 2.75 cm from the heart.

Observed and Predicted Toxicity in Daily Cone-Beam CT-Based Online Adaptive Stereotactic Partial Breast Irradiation with Decreased PTV Margins

PURPOSE/OBJECTIVE(S)

Accelerated partial breast irradiation (APBI) delivers smaller radiation volumes over less time compared to whole breast irradiation (WBI), but the organ-at-risk (OAR) sparing allowed by its large (up to 1 cm) planning target volume (PTV) can be improved. PTV can be decreased with daily online adaptive planning, which we hypothesized yields low rates of adverse events observed and predicted by normal tissue complication probability (NTCP) models.

MATERIALS/METHODS

Intensity-modulated (IMRT) cone-beam CT (CBCT)-based daily online adaptive stereotactic PBI (A-SPBI) plans with 3-mm PTV from 8 patients were recreated with 1-cm PTV per the Florence APBI IMRT trial planning guideline. Dose statistics with evidence for association with toxicity were compared. Documented toxicities were collected for patients treated with A-SPBI with a minimum follow-up of 3.5 months and Common Terminology Criteria for Adverse Events (CTCAE) v.5.0 grade was assigned. Using α/β = 3 for breast and lung, dose statistics were converted to equivalent doses in 2-Gy fractions (EQD2) for use in NTCP models and for comparison using paired t tests, with differences considered significant if p≤0.05.

RESULTS

The table details EQD2 dose statistics for breast, lung, and cosmetic toxicity for A-SPBI plans with 3-mm PTV and their 1-cm PTV re-plans in 8 patients. PTV volume, mean lung dose (MLD), and lung V5, V20, and V30 were significantly lower in 1-cm plans. Acute, subacute (3-6 months), and late toxicities were collected for 30 patients followed for a median of 8 months (range 4-13 months). Radiation dermatitis was the most common acute toxicity (n = 16, 53%), followed by hyperpigmentation (n = 12, 40%), fibrosis (n = 9, 30%), and fatigue (n = 9, 30%). One grade 3 radiation dermatitis was the only grade ≥3 toxicity. Six patients (20%) acutely developed breast or axillary edema: 4 (13.3%) resolved, and 2 (6.7%) developed acutely and persist at last follow-up, >6 months after RT. No patient had a lung V20, V30, or MLD meeting thresholds for radiation-induced lung injury, radiation pneumonitis, or symptomatic or imaging-based pneumonitis models, respectively. The breast V55 model predicted a median risk of unfavorable cosmesis of 33% (range 26-44%) for A-SBPI plans and 35% (range 28-51) for 1-cm PTV plans (p = 0.28).

CONCLUSION

Observed acute toxicities are tolerable and rarely persist in patients treated with A-SPBI with 3-mm PTV margins with daily CBCT-based online adaptation. NTCP modeling predicts similar cosmetic outcome to 1-cm margins. The significant reduction in ipsilateral lung dose with a 3-mm PTV in our first 8 patients especially supports daily adaptation in low-risk breast cancer patients with smoking history and/or lung comorbidity.

Deep Learning-Based Quality Assurance for Auto-Segmentation Masks in Radiotherapy

PURPOSE/OBJECTIVE(S)

Deep learning-based auto-contouring has shown great promise in several disease sites including GU and head and neck. However, quality assurance (QA) is key to identify poor auto-contours which is time consuming. We hypothesis that training a deep learning model to predict contour quality metrics, such as Dice coefficients (DSC) and associated uncertainties for QA.

MATERIALS/METHODS

We trained a 3D U-Net-based DL model for segmenting the target and three clinical-relevant OARs (bladder and rectum). To mimic the slice-by-slice review process in clinical practice, we then trained a 2D ResNet-based DL model to predict the 2D DSC for each 2D slice's contour, generated by the 3D segmentation model. Using the Monte Carlo dropout technique, we made 20 independent predictions per slice, with the final DSC calculated as their average and uncertainty estimated as 95% prediction intervals (PI). The study cohort consisted of 912 prostate cancer patients who received definitive radiotherapy. The 3D auto-segmentation model was trained on 129 patients and validated on 20, before being tested on 763 patients. The 2D DSC prediction model was trained on 293 patients with 11116 slices, validated on 73 patients with 2804 slices, and tested on 366 patients with 14117 slices. Rectum was chosen to test the 2D contour QA model as it is the most challenging OAR. We categorized 2D slices into three groups based on the lower and upper bounds of the prediction intervals. "no/minor edits" (lower bound > = 0.9), "major edits" (lower bound < 0.9 and upper bound > = 0.8), and "not acceptable" (upper bound < 0.8). The model performance was quantified by calculating correlation coefficients between predicted and ground truth DSC and the fraction of cases that were correctly identified in each category.

RESULTS

The results of the study showed that the overall correlation coefficient between predicted, and ground truth DSC was 0.842. The model was able to correctly identify 78.3%, 60.7%, and 53.4% of the "no/minor edits", "major edits", and "not acceptable" cases, respectively.

CONCLUSION

This study provides a valuable tool for clinicians in making quick decisions on the acceptance, rejection, or revision of auto-segmented masks during the radiation therapy planning process by providing quantitative results on predicted DSC and associated uncertainties.

Dosimetric Comparison of Adaptive Radiotherapy Modalities for Stereotactic Partial Breast Irradiation

PURPOSE/OBJECTIVE(S)

An increase in the availability of adaptive radiotherapy (ART) platforms have proven to be effective in the treatment of a variety of sites. In this study, we aim to evaluate the effectiveness of non-adaptive RT and 3 different ART platforms: (1) CBCT-based, (2) CT-based, and (3) MRI-based for stereotactic partial breast irradiation (SPBI).

MATERIALS/METHODS

Data were collected from 32 patients (16 left and 16 right breast) treated at a single institution. 16 patients (8 left and 8 right) treated using the non-ART platform were re-planned onto two different ART platforms, CBCT- and MRI-based. The remaining 16 patients treated using CT-based adaptive platform were not re-planned due to the prone patient treatment position (others systems supine). All cases were planned to 30 Gy in 5 fractions. Plan quality was evaluated based on pre-defined planning goals to the OARS: ipsilateral and contralateral lungs (Dmean, Dmax, V20 Gy, V9 Gy), ipsilateral (V15 Gy, V30 Gy) and contralateral breasts (Dmax), heart (Dmean, Dmax, V3 Gy, V1.5 Gy), skin (Dmax, V36.5 Gy), and rib (Dmax, V30 Gy). Target goals were defined by Dmax, Dmin, gradient index, and paddock conformality index. Re-planned cases were compared within the cohort using a paired t-test and a 2-sided t-test was used comparing to the CT-based platform.

RESULTS

Comparing the left and right breast cohort across all platforms, the CT-based ART system showed a signification dose reduction in Dmean (p<0.001 for all platforms), Dmax (p<0.001 for left breast, p<0.03 for right breast) and V9 Gy (p<0.004 for left breast, p<0.001 for right breast) to the ipsilateral lung, V15 Gy (p<0.004 for left breast cohort) to the ipsilateral breast, and Dmax to the contralateral breast (p<0.001) and ribs (p = 0.01, p<0.001, p = 0.01 for CBCT-ART, MRI-ART, and non-ART for left breast cohort only). On average, the MR-Linac platform showed the least degree of OAR sparing across nearly all dosimetric parameters evaluated when compared to all modalities, especially for contralateral lung Dmean and Dmax (p<0.05 for all dosimetric parameters for all platforms) and contralateral breast Dmax (p<0.003 for all platforms). The CBCT-based platform showed superior dose reduction in contralateral lung mean (p<0.03 for all platforms) and heart Dmean (p = 0.065, p<0.001, p = 0.045 for non-adaptive, MRI-ART, and CT-ART for left breast and p<0.008 for right breast). PTV coverage was comparable across all platforms, averaging at approximately 95%. The CT-based ART platform showed a significantly reduced gradient index relative to the CBCT- and MRI-based platforms (p<0.001).

CONCLUSION

For SPBI treatments, the CT-based ART platforms displayed a higher degree of OAR sparing for many of the dosimetric parameters recorded relative to the other ART and non-ART platforms presented. The MRI-based system typically showed less reduced OAR sparing; however, the advantage of the system is shown if soft tissue contrast is needed. PTV coverage remained comparable across all platforms.

Balancing Quality and Efficiency of Head and Neck Contour Revision for Online Adaptive Radiotherapy

PURPOSE/OBJECTIVE(S)

The number of target and organs-at-risk (OAR) structures requiring contours is a barrier to online adaptive radiotherapy (oART) implementation for head and neck (H&N) cancer. In sharing our experience utilizing a cone beam CT-based oART system featuring automatic contours, we analyzed the system's clinical performance and the dosimetric benefits of human supervision to investigate the optimal balance between contour editing and plan quality.

MATERIALS/METHODS

We analyzed 44 H&N patients and 349 adaptive fractions treated on the oART system. The unsupervised (automatically generated) and supervised (edited by clinicians) target and OAR contours as well as the corresponding adaptive plans were acquired. Dice Similarity Coefficient (DSC) and Hausdorff Distance (HD) used to assess the geometric extent of contour supervision. We mapped the clinically treated adaptive plan to the unsupervised contours to quantify the dosimetric effect of the contour edits, and the adaptive plan optimized from the unsupervised contours to the supervised contours to simulate an unsupervised workflow.

RESULTS

The targets were edited in >80.7% of the sessions, with the most changes seen in the primary GTV (DSC = 0.86 ± 0.09 and HD = 2.77 ± 1.58 mm) and the least in the nodal CTV (DSC = 0.92 ± 0.06, HD = 2.29 ± 1.49 mm). Among OARs, oral cavity was the most frequently edited (49.0%) and brainstem the least (2.2%). In general, OAR edits were minor (mean DSC > 0.95 with std Dosimetric quantification of the edits (Table 1) showed that while the unsupervised targets resulted in significant coverage loss, the change in unsupervised OAR dose was not as pronounced, with 81.5-96.8% still meeting the preplan constraints. Edits corresponding to major dose changes were mostly adjacent to or inside targets. The unsupervised workflow underdosed the targets and overdosed the OARs, and therefore is not recommended.

CONCLUSION

While target contours needed physician supervision in H&N oART, edits to automatic OAR contours were minor. An alternative contour workflow could be adopted to focus on the targets and reduce time spent on the OARs. For OAR close to or overlapping with the targets, strategic cropping could potentially minimize time for editing and improve the robustness of the adapted plan quality.

Enough and Some to Spare: Improved OAR Sparing with Daily Online Cone Beam Adaptive Radiation Therapy (OnC-ART) of the Cervix

PURPOSE/OBJECTIVE(S)

The standard of care treatment for locally advanced cervical cancer involves pelvic chemoradiation. During treatment planning, the cervix and uterus contours are expanded by 1.5 to 2 cm margins to account for inter- and intrafractional motion per the consensus guidelines. Daily online cone-beam adaptive radiation therapy (OnC-ART) accounts for interfractional motion, thus significantly reducing CTV to PTV margins. In this study, we compared the dosimetry of standard larger margin plans (IGRT) to 0.5 cm margins for patients treated with daily OnC-ART and hypothesized that daily OnC-ART with reduced margins will have improved dosimetry.

MATERIALS/METHODS

A retrospective cohort of 10 patients with cervical cancer (stage IIB - IIIC2) treated with 260 definitive daily fractions of OnC-ART chemoradiation between April 2021 and December 2022 was included. Initial plans were generated with OnC-ART and IGRT CTV to PTV margins as follows: combined cervix, uterus, and GTV (0.5 cm vs. 1.5 cm), combined parametria and vagina (0.5 cm vs. 1 cm), nodal chains (0.5 cm vs. 0.5 cm), and gross nodes (0.5 cm vs. 0.5 cm). The initial IGRT plan was copied to synthetic CTs generated for each fraction in the adaptive workflow containing the daily contours of all targets and OARs. The dosimetry of each IGRT fraction was compared to the dose delivered from each daily OnC-ART fraction. Statistical significance was defined as p < 0.05.

RESULTS

When compared with dosimetry from daily IGRT, the daily OnC-ART plans had significantly improved CTV coverage and less hotspots with improvements in D95% (+1.6%), D99% (+2.9%), and Dmax (-0.9%). Bowel bag and bowel loops showed significant improvements in Dmax (-1.4% and - 2.6%), V40 (-6.2% and -5.3%), and V45 (-6.1% and 5.5%). The daily OnC-ART plans had a mean bowel bag V40 of 177.4 cm3. Contrastingly, the mean bowel bag V40 for the large margin IGRT plans was 268.7 cm3. The bladder and rectum also showed significant improvements in Dmax (-1.7% and -1.6%), V40 (-25.2% and -36.0%), and V30 (-9.7% and -17.1%). The daily OnC-ART plans had a mean bladder and rectum V40 of 41.6 cm3 and 18.4 cm3, and the large margin IGRT plans had a mean bladder and rectum V40 of 65.1 cm3 and 40.8 cm3. Bone marrow had a significantly reduced dose with improvements in Dmean (-3.2%), V10 (-2.7%), and V20 (-3.3%).

CONCLUSION

Reduced CTV to PTV margins achievable with daily OnC-ART is shown to not only improve sparing of critical OARs, especially the bladder and rectum, but also improves target coverage compared to larger margins from daily IGRT. The clinical impact of these dosimetric improvements is currently undergoing investigation.

Inherited Reticulate Pigmentary Disorders

Reticulate pigmentary disorders (RPDs) are a group of inherited and acquired skin conditions characterized by hyperpigmented and/or hypopigmented macules. Inherited RPDs include dyschromatosis symmetrica hereditaria (DSH), dyschromatosis universalis hereditaria (DUH), reticulate acropigmentation of Kitamura (RAK), Dowling-Degos disease (DDD), dyskeratosis congenita (DKC), Naegeli-Franceschetti-Jadassohn syndrome (NFJS), dermatopathia pigmentosa reticularis (DPR), and X-linked reticulate pigmentary disorder. Although reticulate pattern of pigmentation is a common characteristic of this spectrum of disorders, the distribution of pigmentation varies among these disorders, and there may be clinical manifestations beyond pigmentation. DSH, DUH, and RAK are mostly reported in East Asian ethnicities. DDD is more common in Caucasians, although it is also reported in Asian countries. Other RPDs show no racial predilection. This article reviews the clinical, histological, and genetic variations of inherited RPDs.

Genetics of Generalized Pustular Psoriasis: Current Understanding and Implications for Future Therapeutics

Psoriasis is a chronic inflammatory skin disease characterized by the appearance of clearly demarcated erythematous and scaly plaques. It can be divided into various types, including plaque, nail, guttate, inverse, and pustular psoriasis. Plaque psoriasis is the most commonly occurring type, though there is another rare but severe pustular autoinflammatory skin disease called generalized pustular psoriasis (GPP), which manifests with acute episodes of pustulation and systemic symptoms. Though the etiopathogenesis of psoriasis is not yet fully understood, a growing body of literature has demonstrated that both genetic and environmental factors play a role. The discovery of genetic mutations associated with GPP has shed light on our comprehension of the mechanisms of the disease, promoting the development of targeted therapies. This review will summarize genetic determinants as known and provide an update on the current and potential treatments for GPP. The pathogenesis and clinical presentation of the disease are also included for a comprehensive discussion.

[Energy metabolism characteristic with risk of secondary bacterial infection in patients with hepatitis B virus-related chronic liver disease]

Objective: To investigate and analyze the energy metabolism characteristics and the correlation between energy metabolism and the risk of secondary bacterial infection in patients with hepatitis B virus-related chronic liver disease (HBV-CLD). Methods: Data of 183 cases admitted to the Mengchao Hepatobiliary Hospital of Fujian Medical University from November 2017 to November 2020 were retrospectively analyzed. 79 cases of chronic hepatitis B, 51 cases of hepatitis B-related liver cirrhosis, and 53 cases of hepatitis B-related liver failure were collected. Among them patients with liver failure and decompensated liver cirrhosis were defined as severe liver disease group. The Quark RMR indirect calorimetry (COSMED Corporation, Italy) was used to exam the patients' energy metabolism condition, and the incidences of secondary bacterial infection of the patients during hospitalization were recorded. Shapiro-Wilk test and normal QQ plot were used to analyze the normal distribution of continuous variable data, which was consistent with the normal distribution and was described by mean ± standard deviation. In addition, if it did not conform to the normal distribution, the median and interquartile distance were used to describe it. Levene's test was used to test the homogeneity of variance of the data, which was consistent with the normal distribution. The t-test was used to compare the means of the two groups of samples. One-way analysis of variance was used to compare the mean values of the three groups of samples, and then the Tukey's test was used to compare the two groups. If the variance was uneven or did not conform to the normal distribution, the Wilcoxon rank sum test was used to compare the differences between the two groups. Kruskal-Wallis test (H test) was used to compare the differences between the three groups of samples, and then the Dunnett's test (Z test) was used for comparison between the two groups. Categorical variable data were analyzed using chi-square test. Logistic regression analysis was used to screen independent risk factors, and the criteria for variable inclusion (P < 0.05). Results: The respiratory entropy (RQ) and non-protein respiratory entropy (npRQ) of the three groups had statistically significant difference (P < 0.05). Among them, the RQ and npRQ of the chronic hepatitis B group were higher than hepatitis B-related liver cirrhosis group and hepatitis B-related liver failure group. There were statistically significant differences in fat oxidation rate (FAT%) and carbohydrate oxidation rate (CHO%) between the three groups (P < 0.05). Compared with hepatitis B-related liver cirrhosis group and hepatitis B-related liver failure group, chronic hepatitis B group (P < 0.05) had lower FAT% and higher CHO%. There were no statistically significant differences in the measured and predicted resting energy expenditure and protein oxidation rate (PRO%) between the three groups. The incidence of secondary bacterial infection in patients with severe liver disease was 48.39% (45/93). Compared with the non-infected group, the RQ and npRQ values ​​of the infected group were significantly decreased (P < 0.05), while FAT% was significantly increased (P < 0.05). Logistic regression analysis showed that glutamyltransferase, cholesterol, and npRQ were independent risk factors for secondary bacterial infections in patients with severe liver disease. Glutamyltransferase elevation, and cholesterol and npRQ depletion had suggested an increased risk of secondary bacterial infection. Subgroup analysis of patients with hepatitis B-related liver failure also showed that compared with non-infected group, RQ value and npRQ value of secondary bacterial infection group were significantly decreased (P < 0.05), while FAT% was significantly increased (P < 0.05). Conclusion: Patients with hepatitis B virus-related chronic liver disease generally have abnormal energy metabolism. Low RQ, npRQ, CHO% and high FAT% are related to the severity of the disease; while npRQ reduction is related to the risk of secondary bacterial infection in patients with severe liver disease, and thus can be used as a clinical prognostic indicator.

[Effect of overexpression of apoptosis-stimulating protein 2 of p53 on activation and apoptosis of hepatic stellate cells induced by transforming growth factor-β1 and its mechanism]

Objective: To study the effect of apoptosis-stimulating protein 2 of p53 (ASPP2) on the activation and apoptosis of hepatic stellate cells induced by transforming growth factor-β1 (TGF - β1), and to explore the role of autophagy in this process. Methods: Mouse hepatic stellate cells were primarily isolated and cultured with green fluorescent protein (GFP) expressing empty vector adenovirus (Ad-GFP) and ASPP2 expressing adenovirus (Ad-ASPP2) for 12 h by transfection kit, and then treated with TGF-β1 (10ng/ml) for 24 h. The experiments were grouped as follows: control group: green fluorescent protein (GFP) expressing empty vector adeno (Ad-GFP); experimental group 1: transfected with Ad-GFP and added with TGF-β1; experimental group 2: transfected with Ad-ASPP2 and induced by TGF-β1. Western blot and quantitative fluorescence PCR were used to detect the expression of ASPP2, α-smooth muscle actin (SMA). At the same time, autophagy was determined by microtubule-associated protein 1 light chain 3-β (LC3). Autophagy and apoptosis of MHSc were observed by immunocytochemistry and RNA interference (RNAi). Multiple pairwise-comparisons between the mean of groups was performed by one-way ANOVA. Results: The relative expression of α-SMA mRNA in mHSC of TGF-β1 + Ad-GFP group (16.83 ± 2.41) was significantly higher than Ad-GFP group (3.62 ± 0.56) (P < 0.05), while the relative expression of α-SMA mRNA (4.22 ± 0.48) in TGF-β1 + Ad-GFP group was significantly lower than TGF-β1 + Ad-GFP group (P < 0.05). The expression of α-SMA protein in each group was consistent with mRNA expression. The proportion of mHSC autophagy in TGF-β1 + Ad-GFP group (80%) was significantly higher than Ad-GFP group (35%); however, there was no statistically significant difference between the two groups. The proportion of mHSC autophagy in TGF-β1 + Ad-ASPP2 group was 42%, which was significantly lower than TGF-β1 + Ad-GFP group, but the apoptotic rate was significantly increased. Cells were simultaneously treated with autophagy inhibitors 3-MA and TGF-β1. The level of autophagy was not statistically significantly different from that of TGF-β1 + Ad-ASPP2 group, but the apoptotic rate was increased. In addition, the RNAi group added with ASPP2 had increased autophagy (LC3-II/LC3-I) than control RNAi group, and the rate of apoptosis was significantly decreased. Conclusion: Overexpression of ASPP2 can alleviate the activation of mHSC and promote the apoptosis of HSC by inhibiting autophagy, so as to alleviate liver fibrosis.

Aeromonas shuberti as a cause of multi-organ necrosis in internal organs of Nile tilapia, Oreochromis niloticus

A disease with white spots in internal organs of Nile tilapia occurred in Zhanjiang, southern China. Multiple, white nodules, 0.8-2.2 mm in diameter, were scattered throughout the liver, spleen and kidney of diseased fish. Signs of nodules reproduced after artificial infection with the isolated strain. Isolated bacteria were Gram-negative, facultative anaerobic, motile, short rod-shaped, with a length of 1.2-2.2 μm. Morphological and biochemical tests, as well as phylogenetic analysis, all strongly indicated that the isolate from tilapia is identical to Aeromonas schubertii (A. schubertii) which temporary named LF1708 strain. Antibiotic sensitivity assays showed the LF1708 is sensitive to 24 of 27 tested antibiotics. Pathogenicity test revealed that the isolate at the dose of 3.75 × 10⁶ CFU/g killed 100% of experimental tilapia within 2 days and the dose of 1 × 10⁷ CFU/g killed 100% of experimental zebrafish within 1 day. Histopathology of diseased tilapia infected with A. schubertii showed numerous necrotic lesions widely distributed in spleen, liver and kidney, and infiltration with a large number of bacteria. To our knowledge, this was the first report that associated A. schubertii with mortality in tilapia.

Association between use of FK506 and prevalence of post-transplantation diabetes mellitus in kidney transplant patients

BACKGROUND

Tacrolimus (FK506) use has been suggested as a risk factor for post-transplantation diabetes mellitus (PTDM) because it can impair insulin secretion. This association warrants further investigation. This study aimed to examine the prevalence of PTDM and its association with FK506 use in kidney transplant recipients. The study also aimed to examine the relationship of FK506 use and diabetes-related biologic markers.

METHODS

A retrospective chart review was used to collect data at a medical center in northern Taiwan from September 2003 to February 2012. PTDM was defined with the use of the criteria of the American Diabetes Association.

RESULTS

Among 166 patients included in the analysis, PTDM was reported in 49 patients (29.5%). A total of 93 patients used the FK506 regimen, of whom 34 (36.6%) were PTDM cases. Logistic regression showed that FK506 use (odds ratio [OR], 2.71; 95% confidence interval [CI], 1.20-6.11; P = .016) and older age (OR,1.08; 95% CI, 1.03-1.13; P = .001) were significant risk factors for PTDM. In addition, FK506 use in PTDM cases was associated with a significantly higher hemoglobin A1c level (7.55 vs 5.81; P = .01) and a borderline significantly higher insulin resistance index (3.24 vs 1.92; P = .053) than was FK506 use without the presence of PTDM.

CONCLUSIONS

Older age and an FK506 regimen were important predictors of the prevalence of PTDM. Greater early detection and prevention efforts for PTDM are needed for older transplant recipients. PTDM patients with an FK506 regimen had higher hemoglobin A1c levels and insulin resistance index than did patients who did not use FK506. The association of serum indicators with FK506 use in the prevalence of PTDM warrants further investigation.

A microwave applicator for uniform irradiation by circularly polarized waves in an anechoic chamber

Microwave applicators are widely employed for materials heating in scientific research and industrial applications, such as food processing, wood drying, ceramic sintering, chemical synthesis, waste treatment, and insect control. For the majority of microwave applicators, materials are heated in the standing waves of a resonant cavity, which can be highly efficient in energy consumption, but often lacks the field uniformity and controllability required for a scientific study. Here, we report a microwave applicator for rapid heating of small samples by highly uniform irradiation. It features an anechoic chamber, a 24-GHz microwave source, and a linear-to-circular polarization converter. With a rather low energy efficiency, such an applicator functions mainly as a research tool. This paper discusses the significance of its special features and describes the structure, in situ diagnostic tools, calculated and measured field patterns, and a preliminary heating test of the overall system.

Investigation of pulsed low dose rate radiotherapy using dynamic arc delivery techniques

There has been no consensus standard of care to treat recurrent cancer patients who have previously been irradiated. Pulsed low dose rate (PLDR) external beam radiotherapy has the potential to reduce normal tissue toxicities while still providing significant tumor control for recurrent cancers. This work investigates the dosimetry feasibility of PLDR treatment using dynamic arc delivery techniques. Five treatment sites were investigated in this study including breast, pancreas, prostate, head and neck, and lung. Dynamic arc plans were generated using the Varian Eclipse system and the RapidArc delivery technique with 6 and 10 MV photon beams. Each RapidArc plan consisted of two full arcs and the plan was delivered five times to achieve a daily dose of 200 cGy. The dosimetry requirement was to deliver approximately 20 cGy/arc with a 3 min interval to achieve an effective dose rate of 6.7 cGy min⁻¹. Monte Carlo simulations were performed to calculate the actual dose delivered to the planning target volume (PTV) per arc taking into account beam attenuation/scattering and intensity modulation. The maximum, minimum and mean doses to the PTV were analyzed together with the dose volume histograms and isodose distributions. The dose delivery for the five plans was validated using solid water phantoms inserted with an ionization chamber and film, and a cylindrical detector array. Two intensity-modulated arcs were used to efficiently deliver the PLDR plans that provided conformal dose distributions for treating complex recurrent cancers. For the five treatment sites, the mean PTV dose ranged from 18.9 to 22.6 cGy/arc. For breast, the minimum and maximum PTV dose was 8.3 and 35.2 cGy/arc, respectively. The PTV dose varied between 12.9 and 27.5 cGy/arc for pancreas, 12.6 and 28.3 cGy/arc for prostate, 12.1 and 30.4 cGy/arc for H&N, and 16.2 and 27.6 cGy/arc for lung. Advanced radiation therapy can provide superior target coverage and normal tissue sparing for PLDR reirradiation of recurrent cancers, which can be delivered using dynamic arc delivery techniques with ten full arcs and an effective dose rate of 6.7 ± 4.0 cGy min⁻¹.

In vitro studies of composite bone filler based on poly(propylene fumarate) and biphasic α-tricalcium phosphate/hydroxyapatite ceramic powder

While many different filler materials have been applied in vertebral augmentation procedures, none is perfect in all biomechanical and biological characteristics. To minimize possible shortages, we synthesized a new biodegradable, injectable, and premixed composite made from poly(propylene fumarate) (PPF) and biphasic α-tricalcium phosphate (α-TCP)/hydroxyapatite (HAP) ceramics powder and evaluated the material properties of the compound in vitro. We mixed the PPF cross-linked by N-vinyl pyrrolidinone and biphasic α-TCP/HAP powder in different ratios with benzoyl peroxide as an initiator. The setting time and temperature were recorded, although they could be manipulated by modulating the concentrations of hydroquinone and N,N-dimethyl-p-toluidine. Degradation, cytocompatibility, mechanical properties, and radiopacity were analyzed after the composites were cured by a cylindrical shape. We also compared the study materials with poly(methyl methacrylate) (PMMA) and PPF with pure HAP particles. Results showed that lower temperature during curing process (38-44°C), sufficient initial mechanical compressive fracture strength (61.1±3.7MPa), and gradual degradation were observed in the newly developed bone filler. Radiopacity in Hounsfield units was similar to PMMA as determined by computed tomography scan. Both pH value variation and cytotoxicity were within biological tolerable limits based on the biocompatibility tests. Mixtures with 70% α-TCP/HAP powder were superior to other groups. This study indicated that a composite of PPF and biphasic α-TCP/HAP powder is a promising, premixed, injectable biodegradable filler and that a mixture containing 70% α-TCP/HAP exhibits the best properties.

Establishing a 'Physician's Spiritual Well-being Scale' and testing its reliability and validity

The purpose of this study was to develop a Physician's Spiritual Well-Being Scale (PSpWBS). The significance of a physician's spiritual well-being was explored through in-depth interviews with and qualitative data collection from focus groups. Based on the results of qualitative analysis and related literature, the PSpWBS consisting of 25 questions was established. Reliability and validity tests were performed on 177 subjects. Four domains of the PSpWBS were devised: physician's characteristics; medical practice challenges; response to changes; and overall well-being. The explainable total variance was 65.65%. Cronbach α was 0.864 when the internal consistency of the whole scale was calculated. Factor analysis showed that the internal consistency Cronbach α value for each factor was between 0.625 and 0.794 and the split-half reliability was 0.865. The scale has satisfactory reliability and validity and could serve as the basis for assessment of the spiritual well-being of a physician.

Water extract of Zizyphus Jujube attenuates ischemia/reperfusion-induced liver injury in rats (PP106)

AIMS

Ischemia and reperfusion (I/R) injuries in the liver remain important clinical problems. Free oxygen radicals and nitrosative stress have been shown to be involved in the pathogenesis I/R-related liver injury. The purpose of this study was to characterize the effects of an extract of Zizyphus Jujube (ZJ), which has strong antioxidant effects, on I/R-induced liver injury.

MATERIALS AND METHODS

Ischemia (I) was induced in rat livers by clamping the common hepatic artery and portal vein for 40 minutes, after which flow was restored, and the liver was reperfused for 90 minutes. Blood samples were collected prior to I and after reperfusion to assay blood levels of alanine transaminase (ALT), lactic dehydrogenase (LDH), oxygen radical (OH), and nitric oxide (NO). In the pharmacologic intervention group a water extract of the fruit of ZJ was administered orally to rats (100 mg/mL for 7 days) that were subsequently exposed to the I/R liver injury.

RESULTS

The data showed that reperfusion (R) of the liver produced increases in blood concentrations of ALT (41.9+/-8.2 vs 338.0+/-89.6; P<.01; N=7) and LDH (317+/-129 vs 4073+/-950; P<.001; N=7). Oxygen radicals (55.1+/-14.3 vs 262.4+/-60.3; P<.001; N=7) and NO (69.3+/-14.9 vs 121.6+/-27.1; P<.01; N=7) also increased significantly in this R group. In the ZJ intervention group the liver injury, oxidative stress, and nitrosative stress were all significantly attenuated.

CONCLUSION

These results suggested that I/R-induced liver injury with white blood cell activation, oxidative stress, and nitrosative stress. Pretreatment with an extract of ZJ, which shows high antioxidant effects, significantly attenuated the I/R-induced liver injury.

Analysis of the factors influencing living kidney donation: the experience in National Taiwan University Hospital

INTRODUCTION

Kidney transplantation provides a choice of active treatment for patients with chronic renal failure. However, the sources of organs are limited; therefore, living kidney donation is an alternative source. The regulation of organ donation in Taiwan stipulates that living organ donation is restricted to living related recipients. We sought to investigate factors that influenced or prevented individuals from living kidney donation in our center.

MATERIALS AND METHODS

From January 2005 to December 2008, there were 266 potential candidates who underwent evaluation for living kidney donation in our center.

RESULTS

Among the potential candidates, most were spouses (n=85, 31.9%), followed by parents (n=67, 25.1%), siblings (n=62, 23.3%), and children (n=40, 15%). Eventually, 124 candidates (47%) completed organ donation, most of whom were siblings (n=39, 31.5%), then parents (n=38, 30.6%), spouses (n=26), and children (n=18). Most donors were females, including mothers and sisters. The most frequent reason to not donate was unwillingness, due to potential influences on their health, economic stress due to suspension of their job, and objection of family members. In 34 candidates (23.9%), adverse health factors of potential candidates prohibited them from donating, including age, chronic medical illness, hepatitis carrier status, severe depression, or mental retardation. Among 59 potential donor-recipient pairs with incompatible ABO blood types or highly sensitized to potential donors, 22 candidates completed living kidney donation.

CONCLUSION

Although laparoscopic nephrectomy for living kidney donation decreases the discomfort and hospital stay after donation, we can only promote living kidney donation if we can deal with the possible factors that prohibit candidates from living kidney donation, such as morbidity after organ donation, anxiety, or other factors. After analyzing those factors, we must also develop a protocol to closely follow the living kidney donors to ensure their health status and relieve their anxiety.

3D simulations of hydrodynamic drag forces on two porous spheres moving along their centerline

This paper numerically evaluates the hydrodynamic drag force exerted on two highly porous spheres moving steadily along their centerline through a quiescent Newtonian fluid over a Reynolds number ranging from 0.1 to 40. At creeping-flow limit, the drag forces exerted on both spheres were approximately identical. At higher Reynolds numbers the drag force on the leading sphere (sphere #1) was higher than the following sphere (sphere #2), revealing the shading effects produced by sphere #1 on sphere #2. At dimensionless diameter beta<2 (beta=d(f)/2k(0.5), d(f) and k are sphere diameter and interior permeability, respectively), the spheres can be regarded as "no-spheres" limit. At increasing beta for both spheres, the drag force on sphere #2 was increased because of the more difficult advective flow through its interior, and at the same time the drag was reduced owing to the stronger wake flow produced by the denser sphere #1. The competition between these two effects leads to complicated dependence of drag force on sphere #2 on beta value. These effects were minimal when beta became low.

Ultra-short metformin pretreatment for clomiphene citrate-resistant polycystic ovary syndrome

OBJECTIVE

To evaluate the effect of ultra-short (12 days) metformin pretreatment in clomiphene-citrate (CC) resistant polycystic ovary syndrome (PCOS).

METHOD

Eighty women with CC-resistant PCOS were randomly allocated to metformin pretreatment or usual treatment. Forty women received 1500 mg metformin daily for 12 days, followed by clomiphene 150 mg daily for 5 days along with metformin. Forty women (control group) received the same dose of clomiphene but no metformin pretreatment.

RESULTS

In the metformin group, 17 (42.5%) women ovulated, and 6 (15%) conceived. In the control group, 5 (12.5%) women ovulated but none conceived. Compared with the control group, the metformin group had significantly higher ovulation (P = 0.03) and pregnancy rates (P = 0.026).

CONCLUSION

Twelve days of metformin pretreatment improves ovulation and pregnancy rates in women with CC-resistant PCOS.

Influence of UNOS status on chance of heart transplantation and posttransplant survival

This study was designed to compare the chance of heart transplantation (HTx) and survival among patients in different UNOS statuses in Taiwan.

METHODS AND RESULTS

From 1996 to 2002, among 203 patients on the heart transplant waiting list, 127 patients had undergone HTx up to December 2002 with 71 dead while waiting, and 5 still alive without transplantation. This study included those 198 patients who had either undergone HTx or who died. At the time of registry, 40 patients were at status IA, 57 at IB, and 101 at II. Nineteen (47.5%) of 40 status IA patients underwent HTx with a mean waiting time of 92 +/- 116 days and median waiting time of 35 days. The 1-month survival was 84%, and 1-year survival was 58%. Seven (64.9%) of 57 status IB patients underwent HTx with a mean waiting time of 85 +/- 100 days and a median waiting time of 40 days. Both 1-month and 1-year survivals were 92%. Seventy-one (70.3%) patients among 101 status II patients underwent HTx. Their mean waiting time was 134 +/- 135 days and median waiting time was 86 days. Their 1-month survival was 95%, and 1-year survival was 85%.

CONCLUSION

Although UNOS status IA patients had a shorter waiting time, their chance to undergo HTx was lower than those in either status IB or status II. The UNOS status IA heart-waiting patients showed lower posttransplant 1-month and 1-year survival rates.

Do patients with acute liver failure have a better chance to receive liver grafting?

OBJECTIVE

Patients with acute hepatic failure (AHF) were always given first priority on the transplant waiting list. We investigated whether AHF patients will deprive other patients on the waiting list of the chance of liver transplantation (LTx).

METHODS AND RESULTS

From January 1999 to March 2003, a total of 423 patients were on the transplant waiting list at the National Taiwan University Hospital. Sixty-five of the patients had AHF caused by hepatitis-B-related disease (HBV, n = 52, 80%), Wilson disease (n = 3, 4.6%), drug-induced AHF (n = 3, 4.6%), and other causes (n = 7, 10.8%).Thirty-three patients died and 16 survived by medical treatment. Two received LTx abroad and 14 underwent LTx at our hospital (7 living-related; 7 cadaver). A total of 140 patients died while waiting for a transplant during the period studied. Of them, 107 were among 358 non-AHF patients (30%), and time-to-death interval was 133 +/- 175 days (median: 62); 33 were among 65 AHF patients (51%); time to death was 19 +/- 28 days (median: 8). There were 35 cadaver donor livers available during the period; 28 of 358 non-AHF patients (7.8%), and 7 of 65 AHF patients (10.7%) received cadaveric LTx. Their waiting time totaled 342 +/- 316 and 12 +/- 9 days, respectively (P < .0001).

CONCLUSION

Most AHF patients died unless they received liver grafts. Even with a higher priority assigned to them, AHF patients still have little chance to get a cadaver donor liver in Taiwan, and non-AHF patients have an even slimmer chance. Therefore, we need to encourage liver donation from living-related donors.

Surfaces with occlusions from layered stereo

We propose a new binocular stereo algorithm that estimates scene structure as a collection of smooth surface patches. The disparities within each patch are modeled by a continuous-valued spline, while the extent of each patch is represented via a pixelwise partitioning of the images. Disparities and extents are alternately estimated in an iterative, energy minimization framework. Experimental results demonstrate that, for scenes consisting of smooth surfaces, the proposed algorithm significantly improves upon the state of the art.

Real-time PCR for rapid genotyping of angiotensin-converting enzyme insertion/deletion polymorphism

OBJECTIVE

To develop a real-time PCR technique for detection of the insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) gene.

DESIGN AND METHODS

Three primers were designed for performing real-time PCR in the presence of SYBR Green I as flurochrome followed by melting curve analysis. Forty human genomic DNA that have been genotyped by two-rounds of conventional PCR were used for evaluation of this technique.

RESULTS

Melting curve analysis indicated the melting peak at 73.9 degrees C and 76.2 degrees C corresponding to the presence of I and D alleles, respectively. Comparable genotyping results were obtained by both conventional and real-time PCR. Besides, the mistyping of ID allele individuals by the first run of conventional PCR were accurately genotyped by single-tube real time PCR.

CONCLUSIONS

The real-time PCR method presented in this study provides a rapid and sensitive way for genotyping of ACE gene that may be suitable for large-scale clinical and epidemiologic study.

Cardiotoxicity in imipramine intoxication: report of one case

Imipramine is the most commonly prescribed tricyclic antidepressant of acute life threatening self-poisoning. We report a 15-month-old boy of accidental poisoning with imipramine, who developed generalized tonic-clonic convulsions and drug-related cardiac conduction abnormalities with PR prolongation, QRS widening, and QTc lengthening. The patient's imipramine level was 1389 ng/ml. The rapid resolution of intraventricular conduction delay and normalization of the QRS-T complexes after gastric lavage, installation of activated charcoal and alkalinization of the blood strongly implicates imipramine intoxication in the etiology of the cardiotoxicity. The patient made a full recovery without neurological sequelae.

Real-time quantitative PCR analysis for alpha-thalassemia-1 of Southeast Asian type deletion in Taiwan

Since homozygosity of the alpha-thalassemia-1 of Southeast Asian (SEA) type deletion results in hydrops fetalis, a novel protocol based on the real-time quantitating polymerase chain reaction (PCR) technique has been developed to quantify the intact and aberrant alpha-globin genes in adults. The ratio of the normal/SEA-bearing alpha-globin genes was expressed in cycle threshold (C(T)) values. Theoretically, a relative ratio of one to one was anticipated in individuals carrying the SEA type deletion. Twenty-five heterozygous and 20 normal cases were analyzed retrospectively with this protocol. Data showed that the CT values for the intact alpha-globin gene allele and the allele bearing the SEA type deletion in carriers were 28.74+/-1.49 and 26.46+/-2.05, respectively. Therefore, the ratio of normal/SEA type deletion-bearing alpha-globin genes in the carriers was 1.09+/-0.043. No ambiguous results were observed from other less common genotypes associated with alpha-thalassemia, such as the Philippine type deletion. Based on the results, we concluded that this protocol could provide a rapid method to mass screen carriers with alpha-thalassemia-1 of SEA type deletion in this region.

The dilemma of "to-be or not-to-be": needs and expectations of the Taiwanese cadaveric organ donor families during the pre-donation transition

There has been little study of the Chinese cadaveric donor family's decisions to donate organs within the Chinese cultural framework. A convenience sample of 25 cadaveric donor family members (12 men, 13 women) who gave their consent to donation at National Taiwan University Hospital agreed to participate in this study and completed in-depth interviews. Data were analyzed by a three-steps within-method qualitative triangulation method. The factors influencing the donor family's decisions to donate organs, the needs of donor families, and their expectations of health care providers during the pre-donation transition--the critical period of time between signing a donation and consent to organ harvesting--were examined. The background context and a conceptual framework were further developed to discuss and depict this phenomenon. This project aims to broaden the horizon on organ donation and contribute to the understanding of some of the psychodynamic issues in the Chinese family in Taiwan.

Specificity of the histopathological triad for the diagnosis of toxoplasmic lymphadenitis: polymerase chain reaction study

Toxoplasmosis is a common cause of lymphadenopathy, but toxoplasmic cysts are not usually found in histological sections used for establishing diagnosis, except on extremely rare occasions. The histopathological triad of florid reactive follicular hyperplasia, clusters of epithelioid histiocytes, and focal sinusoidal distention by monocytoid B cells has been considered to be diagnostic of toxoplasmic lymphadenitis, but the validity of the histopathological triad is based indirectly on serological correlation only. The demonstration of Toxoplasma gondii DNA in lymph nodes displaying the histopathological triad will indicate the validity of the histopathological triad as the criterion for the histopathological diagnosis of toxoplasmic lymphadenitis. We used frozen tissues of 12 lymph nodes with the histopathological triad and tissues of 27 lymph nodes from patients with various other conditions (including 13 cases of follicular lymphoid hyperplasia, FLH; three cases of dermatopathic lymphadenopathy, DPL; two cases of plasmacytosis; two cases of Castleman's disease; two cases of metastatic adenocarcinoma; and five cases of lymphoma) to detect T. gondii DNA by polymerase chain reaction. Ten out of 12 lymph nodes with the triad and six out of 27 lymph nodes without the triad were positive for T. gondii DNA. Thus, the sensitivity of the triad was 62.5% (10/16) and the specificity was 91.3% (21/23). The predictive value of positive tests was 83.3% (10/12) and the predictive value of negative tests was 77.7% (21/27). The six cases positive for T. gondii DNA without the triad were four cases of FLH, one case of DPL, and one case of plasmacytosis. None of the neoplastic diseases was positive. The false positive and negative cases could be due to sampling problems or past T. gondii infection. The results confirm that the histopathological triad is highly specific for the diagnosis of toxoplasmic lymphadenitis and can be used confidently.

Spontaneous closure of ventricular septal defects in the first year of life

BACKGROUND AND PURPOSE

The recent increase in the prevalence of ventricular septal defect (VSD) has been ascribed to the improved detection of small defects with echocardiography and the wider use of screening. The aim of this study was to determine the prevalence and timing of spontaneous closure of specific types of VSD in neonates using echocardiographic screening and follow-up.

METHODS

Two-dimensional color Doppler echocardiography was performed in 3,472 clinically normal full-term neonates born at Cathay General Hospital to detect isolated VSD. The relative prevalence of muscular versus perimembranous defects and their outcome in the first year of life were evaluated.

RESULTS

VSD was found in 74 neonates (34 male, 40 female), resulting in a prevalence of 21.3/1,000 live births. There were 48 muscular, 25 perimembranous, and one subpulmonic defects. Of the 74 patients, 11 were lost to follow-up. Within the observation period of 12 months, spontaneous closure occurred in 40 patients in the muscular group and in six patients in the perimembranous group. The overall rate of spontaneous closure was 73% by the end of the first year. Only five patients with perimembranous defects received digoxin therapy.

CONCLUSIONS

The prevalence of VSD in this series of neonates was 21.3/1,000 live births. The most common location of VSD in the neonatal period was in the region of the muscular septum. Muscular defects were more likely to close spontaneously than perimembranous defects. Most muscular defects underwent spontaneous closure during the 12-month follow-up period.

Induction of disabled-2 gene during megakaryocyte differentiation of k562 cells

Megakaryocyte differentiation is often accompanied by the changes of gene expression pattern. Here we reported that the expression of DAB2, a putative adaptor protein in cell signaling, was induced at the protein and mRNA levels upon 12-O-tetradecanoylphorbol-13-acetate-mediated megakaryocyte differentiation of human chronic myeloid leukemic K562 cells. On the other hand, the differentiation agents DMSO and retinoic acid had no effect on DAB2 expression. Analysis of promoter activity with the human DAB2 luciferase reporter constructs suggested that the regulation is partially at the transcriptional level. The responsive sequences located within an 80-bp DAB2 promoter region. To determine the involvement of MEK1-p42/p44 MAPK pathway in mediating DAB2 gene expression, we have performed the following experiments and found that (i) there was sustained activation of p42/p44 MAPK, but not p38 MAPK, upon K562 cells differentiation; (ii) application of MEK1 inhibitor U0126 reduced the expression of DAB2 protein, mRNA and promoter activity, as well as cell differentiation; (iii) constitutively active MEK1 increased DAB2 promoter activity; and (iv) dominant negative ERK2 abolished constitutively active MEK1-induced DAB2 promoter activity. Taken together, our results indicate that DAB2 gene is induced upon megakaryocyte differentiation by the MEK1-p42/p44 MAPK pathway and may define a new role of DAB2 in hematopoietic cell differentiation.

[The development of a competency-based clinical performance examination model in maternity nursing for BSN graduates]

The purpose of the study was to establish a competency-based clinical performance examination model in maternity nursing for baccalaureate students. Action research was the main research methodology used in the study. A committee, consisting of nursing faculty, students and experienced obstetric nurses, was established to develop the model. Based on intensive literature reviews and standards of nursing practice in Taiwan, the first draft of the model, including the content and process, was created by the committee. The draft then was revised twice after expert review and pilot testing. The revised version of the model was formally implemented into the curriculum to examine the competencies of forty-one BSN students at the end of the perinatal nursing course. Responses from students, clinical examiners, clinical staff and clients were all gathered and integrated to refine the model. The model has content, expert and discriminative validity. The reliability of the model was proven by the high consistency in administration and scoring of the model among clinical examiners.

A common precursor for the three subunits of L-glutamate oxidase encoded by gox gene from Streptomyces platensis NTU3304

A segment of DNA containing the L-glutamate oxidase (gox) gene from Streptomyces platensis NTU3304 was cloned. The entire nucleotide sequence of the protein-coding portion consisting of 2130 bp (710 codons, including AUG and UGA) of the cloned DNA fragment was determined. The gox gene contained only one open reading frame (ORF) which coded for a 78-kDa polypeptide, the precursor of active extracellular Gox. Mature Gox is composed of three subunits, designated as alpha, beta, and gamma, with molecular masses of 39, 19, and 16 kDa, respectively. Analyses of the N-terminal amino acid sequences of the subunits revealed that the order of subunits in the precursor polypeptide encoded by the ORF, from N-terminus to C-terminus, is alpha-gamma-beta. The presence of the flavin adenine dinucleotide (FAD)-binding motif place Gox as a member of the flavoenzyme family. Furthermore, a negative effect of glucose on the biosynthesis of Gox was observed when it was used as carbon source.

Impact of cadaveric organ donation on Taiwanese donor families during the first 6 months after donation

OBJECTIVE

Organ donation is a complex decision for family members of Asian donors. The impact of cadaveric organ donation on both Chinese and Western donor families has not been well investigated within a cultural framework. The purposes of this study were to follow Chinese family members' appraisal of their decision to donate organs, to explore the possible negative and positive impacts of organ donation on their family life, and to determine what help they expected from healthcare providers during the first 6 months after donation.

METHODS

Twenty-two family members (10 men and 12 women) of cadaveric organ donors who signed consent forms at an organ transplant medical center in Taiwan participated in this project and completed in-depth interviews during the sixth month after donation.

RESULTS

Participants were 25 to 56 years old (mean = 48.15 +/- 8.31 years). The type of kinship of the participants included the donor's parents, older sister, and spouse. Subjects reported several negative impacts: worry about the donor's afterlife (86%), stress due to controversy among family members over the decision to donate (77%), and stress due to others' devaluation of the donation (45%). Positive impacts reported by the subjects included having a sense of reward for helping others (36%), having an increased appreciation of life (32%), having closer family relationships (23%), and planning to shift life goals to the study of medicine (9%). Subjects expected the transplant team to provide information about organ recipients (73%), to submit the necessary documents so that family members could receive healthcare payments from the insurance company (68%), to help resolve legal proceedings and settlements associated with accidents (64%), and to not overly publicize their decision to donate (64%).

CONCLUSIONS

Although all of the subjects reported that organ donation was the right decision, the decision to donate did not protect Taiwanese donor families from negative psychocognitive bereavement. The impacts of organ donation were affected by the subject's social cultural, spiritual, and legal context and the nature of their bereavement.

Central venous catheter-induced atrial ectopic tachycardia with reverse alternating Wenckebach periods

A centrally inserted venous catheter may cause atrial ectopic tachycardia. The association of atrial ectopic tachycardia with spontaneous reverse alternating Wenckebach periodicity has rarely been reported. We describe a 4-year-old boy with tetralogy of Fallot who developed atrial ectopic tachycardia with reverse alternating Wenckebach periods postoperatively after central venous catheter placement. All such episodes emerged from a 3:2 atrioventricular block, followed by runs of 2:1 atrioventricular block with progressive shortening of the conducted PR intervals. Normal sinus rhythm returned after the catheter was withdrawn to the superior vena cava. Reverse alternating Wenckebach periodicity may be a tachycardia-dependent physiologic phenomenon.

Real-time PCR for quantitative detection of Toxoplasma gondii

The protozoan Toxoplasma gondii is one of the most common infectious pathogenic parasites and can cause severe medical complications in infants and immunocompromised individuals. We report here the development of a real-time PCR-based assay for the detection of T. gondii. Oligonucleotide primers and a fluorescence-labeled TaqMan probe were designed to amplify the T. gondii B1 gene. After 40 PCR cycles, the cycle threshold values (C(T)) indicative of the quantity of the target gene were determined. Typically, a C(T) of 25.09 was obtained with DNA from 500 tachyzoites of the T. gondii RH strain. The intra-assay coefficients of variation (CV) were 0.4, 0.16, 0.24, and 0.79% for the four sets of quadruplicate assays, with a mean interassay CV of 0.4%. These values indicate the reproducibility of this assay. Upon optimization of assay conditions, we were able to obtain a standard curve with a linear range (correlation coefficient = 0.9988) across at least 6 logs of DNA concentration. Hence, we were able to quantitatively detect as little as 0.05 T. gondii tachyzoite in an assay. When tested with 30 paraffin-embedded fetal tissue sections, 10 sections (33%) showed a C(T) of <40 and were scored as positive for this test. These results were consistent with those obtained through our nested-PCR control experiments. We have developed a rapid, sensitive, and quantitative real-time PCR for detection of T. gondii. The advantages of this technique for the diagnosis of toxoplasmosis in a clinical laboratory are discussed.

Embryonic dormancy phenomenon in obstructed healthy mouse fallopian tubes

PURPOSE

A mouse model of unilateral oviductal obstruction was designed to study whether healthy oviducts can support embryo development in an advanced stage toward blastocyst hatching and implantation when the embryos in the contralateral side normally move into the uterine cavity.

METHODS

The oviducts of 80 female ICR mice (aged 5-8 weeks) were ligated unilaterally 12-40 hr postcoitus. The ligated oviducts were isolated from day 4 to 19.5 postcoitus. Embryos within the ligated oviducts were then flushed out to record the developmental stage and compared with the conceptuses in the contralateral uterine horns with unligated oviducts. Embryos recovered from ligated oviducts were then cultured in vitro to observe their potential for further development.

RESULTS

In 33 mice, 53.4% (163/305) and 86.1% (241/280) of the morphologically normal blastocysts had hatched from the zona pellucida within the obstructed tube and contralateral uterine horns, respectively, on the 5th day postcoitus. The data demonstrated that the hatching process could take place within the obstructed fallopian tube, but the timing was delayed. From 5.5 to 19.5 days postcoitus, a total of 362 implanted embryos were obtained in unligated control uterine horns, but none of the 404 embryos in the artificially obstructed oviducts were implanted. The embryos within the ligated tubes were dormant in the hatched blastocyst stage as demonstrated by their ability to continue growing (98.2%) when removed from the oviduct to an in vitro environment.

CONCLUSIONS

In this study, we demonstrate that mouse embryos can hatch, although delayed, in obstructed healthy oviducts. Tubal pregnancy is not likely to happen in artificially obstructed healthy mouse fallopian tubes, since all the viable embryos were dormant at the hatched blastocyst stage.

The Drosophila PAR domain protein 1 (Pdp1) gene encodes multiple differentially expressed mRNAs and proteins through the use of multiple enhancers and promoters

Transcription factors are often expressed at several times and in multiple tissues during development and regulate diverse sets of downstream target genes by varying their combinatorial interactions with other transcription factors. The Drosophila Tropomyosin I (TmI) gene is regulated by a complex of proteins within the enhancer that synergistically interacts with MEF2 to activate TmI transcription as muscle cells fuse and differentiate. One of the components of this complex is PDP1 (PAR domain protein 1), a basic leucine zipper transcription factor that is highly homologous to three vertebrate genes that are members of the PAR domain subfamily. We have isolated and describe here the structure of the Pdp1 gene. The Pdp1 gene is complex, containing at least four transcriptional start sites and producing at least six different mRNAs and PDP1 isoforms. Five of the PDP1 isoforms differ by the substitution or insertion of amino acids at or near the N-terminal of the protein. At least three of these alternately spliced transcripts are differentially expressed in different tissues of the developing embryo in which PDP1 expression is correlated with the differentiation of different cell types. A sixth isoform is produced by splicing out part of the PAR and basic DNA binding domains, and DNA binding and transient transfection experiments suggest that it functions as a dominant negative inhibitor of transcription. Furthermore, two enhancers have been identified within the gene that express in the somatic mesodermal precursors to body wall muscles and fat body and together direct expression in other tissues that closely mimics that of the endogenous gene. These results show that Pdp1 is widely expressed, including in muscle, fat, and gut precursors, and is likely involved in the transcriptional control of different developmental pathways through the use of differentially expressed PDP1 isoforms. Furthermore, the similarities between Pdp1 and the other PAR domain genes suggest that Pdp1 is the homologue of the vertebrate genes.

The effects of brief gamete co-incubation in human in vitro fertilization

PURPOSE

To investigate whether very short exposure of mature oocytes to sperm in vitro may affect the fertilization rates, embryo cleavage rates, and embryo quality between sibling oocytes in the same patient.

METHODS

Sibling oocytes of the same patient from 23 oocyte collection cycles were randomly allocated to the study group, with a 1-hr or 3-hr sperm-oocyte incubation, or the control group with the standard overnight gamete co-incubation. The fertilization rates, cleavage rates, and subsequent embryo quality were evaluated.

RESULTS

Our results showed no statistically significant differences in fertilization rates, embryo cleavage rates, and quality of the embryos between the study group and the control group.

CONCLUSIONS

Since the present study showed that long exposure of the oocyte to sperm has no advantage over short exposure, we prefer shortening the oocyte-sperm incubation period for reducing the negative effect induced by nonphysiologically high concentrations of spermatozoa.