A Technology-Informed Approach to Clinical Trial Equity

PURPOSE/OBJECTIVE(S)

Despite efforts to increase participation of diverse communities in clinical trials, ethnic/racial minorities remain underrepresented. One such determinant may be lack of access to a comprehensive cancer center that conducts clinical research. Historically, our institution has had low accrual from rural regions further away from our cancer center, with Hispanic or Latino (HL) patients (pts) being especially underrepresented in our clinical research. In this study, we explored the impact of a clinical trial that allowed pts to receive chemotherapy (chemo) with their local oncologist. We hypothesize that allowing pts to receive chemo locally will lead to higher rates of enrollment from populations under-represented in clinical trials.

MATERIALS/METHODS

We conducted a study for pts with rectal cancer to undergo short-course radiation followed by 4 months of chemo with the option to pursue watch and wait if pts achieve a clinical complete response. Radiation was administered at our institution while pts could receive standard-of-care chemo closer to home with their local oncologist. For pts who received chemo locally, the research coordinator and co-investigators held video visits with the pts prior to each chemo infusion to review adverse events (AE), labs, and chemo dosing. We compared demographic data of pts on this trial with that of pts enrolled across all adult therapeutic oncologic clinical trials over the same time period at our institution. Distance to our institution was calculated based on pts' primary residence zip code. Protocol compliance with AE reporting for pts who received chemo locally was assessed by chart review.

RESULTS

Between May 2020 and January 2023, 24/35 enrolled pts completed both radiation and chemo on trial. 13/24 pts (54%) received chemo locally. Of the 24 pts, 16 were White (67%), 7 Asian (29%), 1 Native Hawaiian/ Pacific Islander (4%). Of all enrolled patients, 4 were HL (16.7%), compared to our institutional average of 16.5%. All enrolled HL pts received their chemo locally. The average distance traveled by non-HL pts from their home to our institution was 87.7 miles (range 5.1 - 308). In contrast, HL pts traveled an average of 147.8 miles (range 110 - 249), 68% further than their non-HL counterparts. There was 100% compliance with AE reporting among those pts who received their chemo locally.

CONCLUSION

Although the percentage of HL participation in our study was consistent with our institutional average, all HL pts enrolled on the trial received treatment locally and lived substantially further from our institution than non-HL. By allowing pts to receive this part of treatment locally, we provided pts who live further away an opportunity to engage in clinical research without the associated financial and time toxicities related with traveling for treatment. By decentralizing clinical trials and leveraging telemedicine, we can promote the participation of under-represented groups in clinical trials.

Safety of Radiation Therapy for Treatment of Malignancy in Patients with Inflammatory Bowel Disease

PURPOSE/OBJECTIVE(S)

Inflammatory bowel disease (IBD) has been considered a relative contraindication to radiation therapy (RT) due to the potential greater risk of RT-induced toxicities, however, there is limited toxicity data using modern RT techniques. This study aims to assess toxicity outcomes in patients with IBD treated with abdominal or pelvic RT.

MATERIALS/METHODS

After institutional review board approval, patients with IBD who received RT to the abdomen or pelvis were filtered from an institutional research repository and their electronic medical records were reviewed. Acute toxicity was defined as that occurring within 3 months of RT. Toxicities were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. Univariable Cox proportional hazards regression was used to assess rates of grade ≥2 toxicity-free survival.

RESULTS

We identified 62 patients with median age of 69 years (interquartile range [IQR] 62-77) who received RT from 2006-2022. Median follow up was 15 months (IQR 4-33). Most patients were male (42; 68%) and had a diagnosis of ulcerative colitis (44; 71%). The most common primary malignancy was colorectal/anal (26; 42%). Intensity-modulated RT (IMRT) was most frequently used (38; 61%) followed by 3-dimensional conformal RT (3D-CRT) (12; 19%) and stereotactic body RT (SBRT)/brachytherapy (12; 19%). For IMRT/3D-CRT, median dose delivered was 50 Gy (IQR 49-59) in 25 fractions (IQR 25-30), and median maximum dose (Dmax) to bowel was 48 Gy (IQR 43-52); whereas for SBRT/brachytherapy, the median dose was 32 Gy (IQR 27-40) in 3 fractions (IQR 2-5) and median bowel Dmax was 32 Gy (IQR 20-37). The median biologically effective dose delivered with an assumed alpha/beta ratio of 10 (BED10) across all RT modalities was 63 Gy (IQR 60-72). After initiation of RT, 31 patients (50%) and 14 patients (23%) experienced grade ≥2 acute and late toxicity, respectively. Thirteen patients (21%) and 7 patients (11%) experienced grade 3 acute and late toxicity, respectively. No patients experienced grade >3 toxicity. Acute toxicity resulted in interruption to RT for 5 patients (8%), 2 of which did not resume RT. Four patients (6%) required adjustment to chemotherapy or IBD medication dosage as a result of their acute toxicity. Median time from RT start to acute toxicity onset was 41 days (IQR 32-46), whereas median time to onset of late toxicity was 9 months (IQR 5-15). The most common acute and late toxicities were diarrhea (21; 34%) and bowel obstruction/perforation/fistula (4; 6%), respectively. Rates of grade ≥2 toxicity-free survival overtime were not significantly associated with IBD status (active vs quiescent), delivered BED10, or bowel Dmax BED3.

CONCLUSION

In patients with IBD treated with abdominal or pelvic RT for malignancy, RT was feasible with acceptable rates of toxicity and active versus quiescent IBD status did not impact toxicity outcomes. Future research is needed to elucidate specific dose constraints when treating patients with IBD.

Analysis of the Measured FDG Uptake from the First-in-Human Clinical Trial of Biology-Guided Radiotherapy

PURPOSE/OBJECTIVE(S)

The RefleXion X1 system is a novel linear accelerator equipped with dual 90° PET arcs incorporated into its architecture to capture emissions from tumors and designed to respond by directing the radiation beam towards target. This study reports on the measured FDG uptake from the first in human multi-institutional clinical trial (BIOGUIDE-X) evaluating the performance and safety of the RefleXion X1 PET-LINAC.

MATERIALS/METHODS

A total of nine patients treated with stereotactic body radiotherapy (SBRT) for lung (5) and bone (4) tumors were enrolled in the Cohort II of this study after screening their pre-study diagnostic PET/CT, acquired up to 60 days prior to enrollment, to ensure their tumor size between 2 to 5 cm and SUVmax >6. After CT simulation, the tumor and OARs were delineated, and patients had a 4-pass Imaging-only (BgRT Modeling) PET/CT acquisition on the X1 system to generate biology-guided radiotherapy (BgRT) plans. Before the patients' first and last SBRT fractions, they were injected with FDG, and short PET pre-scan (1-pass) was performed on the X1 followed by a long-PET acquisition (4-pass) to emulate the expected BgRT dose distribution without firing beam. Patients were also imaged on a third-party diagnostic PET/CT scanner after the last-fraction X1 scan. This study compares the SUVmax from the screening PET/CT, X1 Imaging-only scan, X1 PET pre-scan and long scan before the first and last-fractions, and final diagnostic PET/CT.

RESULTS

The median time from injection to PET imaging was 84 ± 15.4 mins for X1 Imaging-only (used for generating BgRT plans), 77 ± 21.6 mins for X1 pre-scan (safety check before treatment start), 108+/- 22 mins for X1 long-PET (used to emulate treatment delivery), and 161 ± 23 mins for final diagnostic PET. For a nominal 10 mCi injection, the mean SUVmax for screening imaging performed on the diagnostic PET/CT was 10.8 ± 4.3. For a 15 mCi nominal injection, the mean SUVmax calculated on the X1 was 5.3 ± 2.6, 5.4 ± 2.0, 5.5 ± 2.6, 5.2 ± 1.8 and 5.4 ± 2.2 for the Imaging-only, first-fraction PET pre-scan, first-fraction long PET scan, last-fraction PET pre-scan, and last-fraction long PET scan, respectively. The overall median SUVmax for all patients across all timepoints and scans with X1 was calculated to be 4.8 with a range of 2.4 to 9.8. The median SUVmax for the diagnostic PET/CT scan after the last fraction X1 scan was 15.8 with a range of 8.5 to 27.7.

CONCLUSION

The dual PET arcs and limited axial extent of the X1 PET subsystem results in lower system sensitivity in comparison to diagnostic PET scanners equipped with full ring and larger axial extent, as expected. With the same FDG injection, the RefleXion X1 produced SUVmax values that were 30.4 % of the diagnostic PET/CT scanners' values. Nevertheless, the X1 collected sufficient emission data to enable successful completion of emulated BgRT deliveries that met dose accuracy criteria in a clinical setting.

Imaging Performance of the PET Scan on a Novel Ring Gantry-Based PET/CT Linear Accelerator System in the First-in-Human Study of Biology-Guided Radiotherapy

PURPOSE/OBJECTIVE(S)

Biology-guided radiotherapy (BgRT) is a novel tracked dose delivery modality using real-time positron emission tomography (PET) to guide radiotherapy beamlets. The present study was performed with sequential cohorts of participants to evaluate the performance and safety of BgRT. Primary endpoints were previously reported. We hereby report on one of the secondary endpoints assessing a novel treatment planning machine with integrated dual kVCT/PET imaging ("novel device") performance in comparison to a third-party diagnostic PET/CT scan.

MATERIALS/METHODS

This single-arm, open-label, prospective study included participants with at least 1 FDG-avid targetable primary or metastatic tumor (≥2cm and ≤5cm) in the lung or bone. PET imaging data were collected on the novel device and on a third-party diagnostic PET/CT performed in sequence once at the planning timepoint in Cohort I, and immediately before the last fraction among patients undergoing stereotactic radiotherapy in Cohort II. Three central read radiation oncologists (CRRO) provided an interpretation of the novel device PET scans which were compared to an agreement standard based on 3 central radiologists' review of the paired diagnostic PET/CT scan. Positive percent agreement for localization of the target tumor within the biology-tracking zone (BTZ) was the key metric because it reflects whether advancing patients to subsequent steps in the BgRT workflow based on the novel device's imaging was ultimately appropriate.

RESULTS

In Cohort 1, 6 image comparisons were performed. The positive (%) agreement for the aggregate radiation oncologist review was 100% (5/5), reflecting that in all 5 cases where the aggregate radiation oncologists deemed the tumor to fall within the BTZ based upon the novel device PET images, the central radiologists came to the same conclusion upon review of the paired diagnostic PET/CT images. The overall (%) agreement for the aggregate radiation oncologist review was 83.3% (5/6): localization was not established on the novel device in 1 case, even though it was established on the diagnostic PET/CT. This would not pose risk in real world practice as BgRT candidacy would be aborted for tumors not visible on the novel device. In Cohort II, among the 7 image comparisons, there was 100% positive percent agreement between the aggregate CRRO and the agreement standard as the localization criteria was met in both scans for all 7 patients. This was concordant with a 100% overall percent agreement.

CONCLUSION

This investigation demonstrated a 100% positive percent agreement between central review of this novel device images by radiation oncologists and central review of the accompanying third-party PET/CT images by radiologists. There were no cases where a positive localization by the aggregate CRRO was not confirmed by the third-party PET/CT standard, providing evidence against the likelihood of falsely positive localizations on the novel device that would inappropriately advance patients in the workflow.

Workflow Considerations for Biology-Guided Radiotherapy (BgRT) Implementation

PURPOSE/OBJECTIVE(S)

Biology-guided radiotherapy (BgRT) is a novel platform that combines real-time PET imaging with a 6MV Linac to target tumors. The performance and safety of BgRT was assessed in the BIOGUIDE-X clinical trial. This study aims to report on the BgRT workflow steps and assess the time required for each step of the BgRT process during this trial.

MATERIALS/METHODS

A total of nine patients were enrolled in the second Cohort of the BIOGUIDE-X study which included patients treated with stereotactic body radiotherapy (SBRT) for lung tumors (5) and bone tumors (4). The pre-treatment BgRT workflow includes CT simulation, contouring, imaging-only (BgRT Modeling) PET acquisition, BgRT planning, patient specific QA and plan approval. The imaging-only PET acquisition on the X1 collects a representative PET volumetric 3D image and is an input to develop the BgRT treatment plan. The steps during the BgRT delivery session are kVCT localization, PET pre-scan, PET evaluation and BgRT delivery. The PET PreScan is a 1-pass short-duration PET acquisition that is used to confirm that the PET biodistribution on the day of treatment is consistent with that of the imaging-only PET. During BIOGUIDE-X, the BgRT delivery step was replaced by a 4-pass long-PET acquisition that was used to emulate the expected BgRT dose distribution without turning the beam on. To assess BgRT workflow, times from 18F-FDG injection to image-only PET acquisition, 18F-FDG injection to PET pre-scan, Pre-scan to PET evaluation, and PET evaluation to BgRT delivery (long PET acquisition) were recorded.

RESULTS

Time between the 18F-FDG injection and the X1 imaging-only PET scan was 84 ± 19 minutes which includes time for 18F-FDG update. Average time to perform imaging-only PET scan was 26 ± 4 minutes. During the BgRT 'delivery' session, the mean time between the kVCT acquisition and PET pre-scan acquisition was 7 ± 3 minutes. The mean time to acquire a 1-pass PET pre-scan was 6 ± 1 then followed by 6 ± 1 minutes for the PET pre-scan dose calculation to estimate the BgRT doses that it would have delivered for this fraction. On average, the PET reconstruction, the PET signal localization verification and the evaluation of safety metrics took 11 ± 4 minutes. The mean time for BgRT 'delivery' was 27 ± 5 minutes based on the 4-pass long PET acquisition. Time from the start of the BgRT session to the end of the BgRT 'delivery' with this version of the investigative product release was 65 ± 9 minutes.

CONCLUSION

The new processes introduced by the BgRT technology were evaluated and found clinically feasible. Improvements are being undertaken to shorten the time required for each step and to increase patient comfort ahead of BgRT clinical implementation.

Mitigation of IMRT/SBRT Treatment Planning Errors on the First Biology-Guided Radiotherapy System Using FMEA within Six Sigma Framework

PURPOSE/OBJECTIVE(S)

Utilize the Six Sigma methodology and Failure Mode and Effect Analysis (FMEA) to prevent and mitigate errors in IMRT/SBRT treatment planning with the first clinical installation of biology-guided radiotherapy (BgRT) system.

MATERIALS/METHODS

The Six Sigma approach consisted of five phases: Define-Measure-Analyze-Improve-Control. The Define-Measure-Analyze phases consisted of process mapping and an FMEA of the IMRT/SBRT treatment planning process on the BgRT system. The multidisciplinary team outlined the workflow process and identified the failure modes associated with the plan check items using AAPM TG-100 recommendations. Items with the highest average risk priority numbers (RPN) and Severity ≥7 were prioritized for automation using the treatment planning system scripting API (ESAPI). The Improve phase consisted of developing ESAPI scripts prior to the launch of the BgRT system to improve efficiency and safety. In the Control phase, the FMEA ranking was re-evaluated 1-year post-clinical launch.

RESULTS

Overall, 100 plan check items were identified where the RPN values ranged from 10.2 to 429.0. Fifty of these items (50%) were suitable for automation within ESAPI. Of the 10 highest-risk items (Table 1), 8 were suitable for automation. Based on the results of the FMEA, two scripts were developed: Planning Assistant used by the planner during preparation for planning and the Automated Plan Check used by the planner and the plan checker during plan preparation for treatment. At 1-year post-clinical launch, the scripts were used for 80 patients successfully treated in 1747 fractions. During this period only 3 errors were reported: omitted bolus during treatment, nomenclature error in the BgRT system plan prescription, and dose tracking plan not approved following physics plan check. The average RPN pre-scripts was 138.0 compared to the average post-scripts RPN of 47.8 (p < 0.05) signifying a safer process.

CONCLUSION

Implementing new technology into the clinic can be an error-prone process where the likelihood of errors increases with increasing pressure to implement the technology quickly. To limit errors in the clinical implementation of the first BgRT system, the Six Sigma methodology was utilized to identify failure modes, establish quality control checks, and re-evaluate these checks 1-year post-clinical launch.

IMRT and SBRT Treatment Planning Study for the First Clinical Biology-Guided Radiotherapy System

Purpose: The first clinical biology-guided radiation therapy (BgRT) system—RefleXion^TM X1—was installed and commissioned for clinical use at our institution. This study aimed at evaluating the treatment plan quality and delivery efficiency for IMRT/SBRT cases without PET guidance. Methods: A total of 42 patient plans across 6 cancer sites (conventionally fractionated lung, head, and neck, anus, prostate, brain, and lung SBRT) planned with the Eclipse^TM treatment planning system (TPS) and treated with either a TrueBeam^® or Trilogy^® were selected for this retrospective study. For each Eclipse VMAT plan, 2 corresponding plans were generated on the X1 TPS with 10 mm jaws (X1-10mm) and 20 mm jaws (X1-20mm) using our institutional planning constraints. All clinically relevant metrics in this study, including PTV D95%, PTV D2%, Conformity Index (CI), R50, organs-at-risk (OAR) constraints, and beam-on time were analyzed and compared between 126 VMAT and RefleXion plans using paired t-tests. Results: All but 3 planning metrics were either equivalent or superior for the X1-10mm plans as compared to the Eclipse VMAT plans across all planning sites investigated. The Eclipse VMAT and X1-10mm plans generally achieved superior plan quality and sharper dose fall-off superior/inferior to targets as compared to the X1-20mm plans, however, the X1-20mm plans were still considered acceptable for treatment. On average, the required beam-on time increased by a factor of 1.6 across all sites for X1-10mm compared to X1-20mm plans. Conclusions: Clinically acceptable IMRT/SBRT treatment plans were generated with the X1 TPS for both the 10 mm and 20 mm jaw settings.

Persistence of choking injuries in children

BACKGROUND

Choking injuries are a significant cause of morbidity and mortality in children and represent a significant public health concern. Evaluating trends and the impact of interventions are essential to highlight whether progress has been made and to target public health efforts.

OBJECTIVE

To investigate how rates of nonfatal and fatal choking injuries have changed before and after 2010 when policy recommendations were made by the American Academy of Pediatrics.

METHODS

A descriptive study investigating unintentional nonfatal and fatal choking injuries in children aged 0-19 years using national data from 2001 to 2016 through the Centers for Disease Control and Prevention's WISQARS™ and WONDER databases, focusing on the 6 years prior and 6 years after release of the AAP's recommendations. The data was categorized by age, gender, year, and race/ethnicity for descriptive and statistical analyses.

RESULTS

From 2001 to 2016, there were a total of 305,814 nonfatal injuries and 2347 choking deaths in children from 0 to 19 years. Children under five years of age accounted for 73% of nonfatal injuries and 75% of choking fatalities. There was a statistically significant increase in the nonfatal injuries rate when comparing 2005-2010 and 2011-2016 (19/100,000 versus 26/100,000, respectively). There was a decrease in the choking fatalities rate in all children (0.18/100,000 versus 0.16/100,000, respectively) but no change in fatalities rate for children under five. White and Black children experience nonfatal choking injuries at a higher rate than Hispanics. Black children had highest rates of choking fatalities over Hispanic, White, Asian, and Alaskan or American Indian ethnicities. The lowest rates of death occurred in Asians.

CONCLUSIONS

Overall rate of nonfatal choking injuries increased, while rate of choking fatalities in children decreased after 2010. However, the choking fatalities rate in 0-4 years olds, the highest risk group, did not change. Racial gaps exist with highest rates of injury in Black children. We must continue to educate and raise awareness of choking injuries, with targeted efforts to address racial disparities.

Surgical management of atypical mycobacterial cervical lymphadenitis in an outbreak of odontological infection

INTRODUCTION

We report on our experience with surgical management of nosocomial Mycobacterium abscessus cervical lymphadenitis in the setting of an epidemic linked to a dental practice in the community.

METHODS

This is an observational case series of children who required surgical treatment of cervical lymphadenitis as part of multidisciplinary management of nosocomial M. abscessus infections. We describe the criteria for surgical management of cervical lymphadenitis as well as patient characteristics and outcomes.

RESULTS

Over 1000 children undergoing pulpectomies and pulpotomies at a local dental practice with a contaminated water source were identified as potentially susceptible to atypical mycobacteria infection, identified as M. abscessus. Between August 2016 and May 2017 108 children underwent inpatient evaluation at our institution by general pediatricians and pediatric infectious disease specialists. 90 children required at least 1 surgical intervention by pediatric otolaryngology and/or oral and maxillofacial surgery (OMFS). Children were evaluated by the Pediatric Otolaryngology service if computer tomography (CT) scan of the neck demonstrated lymph nodes of at least 1.5 cm in shortest dimension or lymph nodes with central hypolucencies suspicious for infection with central necrosis. Pediatric Otolaryngology intervened on 11 patients all of whom required selective cervical lymphadenectomy with or without curettage. These patients ranged in age from 3 to 8 years; 8 were male, 6 had concurrent pulmonary nodules. Two patients underwent curettage in addition to lymphadenectomy. Five patients required at least 2 surgical interventions by Pediatric Otolaryngology.

CONCLUSION

We found M. abscessus to be an aggressive infection requiring early cervical lymphadenectomy in select patients.

A Fully Integrated Quartz MEMS VHF TCXO

We report on a 32-MHz quartz temperature compensated crystal oscillator (TCXO) fully integrated with commercial CMOS electronics and vacuum packaged at wafer level using a low-temperature MEMS-after quartz process. The novel quartz resonator design provides for stress isolation from the CMOS substrate, thereby yielding classical AT-cut f/T profiles and low hysteresis which can be compensated to < ±0.2 parts per million over temperature using on-chip third-order compensation circuitry. The TCXO operates at low power of 2.5 mW and can be thinned to as part of the wafer-level eutectic encapsulation. Full integration with large state-of-the-art CMOS wafers is possible using carrier wafer techniques.

[Clinical efficacy of clear aligners in treating bimaxillary protrusion]

Objective: To evaluate the efficiency of clear aligners in treating bimaxillary protrusion patients with first premolar extractions. Methods: Eleven patients with bimaxillary protrusion were selected in this study. All of them were treated by using clear aligners with four first premolar extractions and need maximal anchorage. Cephalometric analysis was carried out before and after treatment. Results: Cephalometric analysis results showed that significant changes in teeth and profile could be detected after clear aligner treatment and no change could be found in skeletal pattern. Upper and lower anterior teeth were retracted. The control of anterior torque and posterior anchorage were effective. The soft tissue analysis showed that position of upper and lower lip was significantly changed which improve the profile of patients. After treatment, the distance of U1 to NA and L1 to NB reduced by (5.19±4.12) mm and (4.53±1.20) mm, respectively. The differences were statistically significant (P<0.01). Conclusions: Bimaxillary protrusion patients who needed premolar extractions and maximal anchorage could be treated with clear aligners.

[Evaluation of cone-beam computed tomography on upper airway changes after alternating rapid palatal expansion and constriction]

OBJECTIVE

To evaluate the changes of different parts of upper airway after alternating rapid palatal expansion and constriction via three dimensional measurement, compared with the protocol of rapid palatal expansion alone.

METHODS

In the study, 36 patients with retrognathic maxilla were selected and randomized to either group A or group B. The patients in group A were treated with rapid palatal expansion alone. The patients in group B were treated with alternating rapid palatal expansion and constriction. Three dimensional analyses were performed on all pre- and post-treatment cone-beam computed tomography (CBCT) images with the software Dolphin.

RESULTS

Two subjects in group B were lost to follow up during the treatment. The gender distributions, ages and all measuring items before treatment had no significant difference between group A and group B (P>0.05). Nasal floor width, nasal lateral width, nasal volume, and nasopharynx volume increased significantly in each group after rapid palatal expansion alone or rapid palatal expansion and constriction (P<0.05). The variations of oropharyngeal volume and hypopharyngeal volume had no significant difference (P>0.05). No significant difference was observed in the nasal floor width and nasal lateral width increment among the anterior, median and posterior parts in each group either (P>0.05). No significant difference in all the measuring items was observed between the two groups (P>0.05).

CONCLUSION

Alternating rapid palatal expansion and constriction could increase the volume of nasal and naopharynx cavities by the similar way of rapid palatal expansion alone, and had no obvious effect on oropharynx and hypopharynx cavities.

Functional and Histological Effects of Chronic Neural Electrode Implantation

Objectives

Permanent injury to the cranial nerves can often result in a substantial reduction in quality of life. Novel and innovative interventions can help restore form and function in nerve paralysis, with bioelectric interfaces among the more promising of these approaches. The foreign body response is an important consideration for any bioelectric device as it influences the function and effectiveness of the implant. The purpose of this review is to describe tissue and functional effects of chronic neural implantation among the different categories of neural implants and highlight advances in peripheral and cranial nerve stimulation.

Data Sources: PubMed, IEEE, and Web of Science literature search.

Review Methods: A review of the current literature was conducted to examine functional and histologic effects of bioelectric interfaces for neural implants.

Results

Bioelectric devices can be characterized as intraneural, epineural, perineural, intranuclear, or cortical depending on their placement relative to nerves and neuronal cell bodies. Such devices include nerve‐specific stimulators, neuroprosthetics, brainstem implants, and deep brain stimulators. Regardless of electrode location and interface type, acute and chronic histological, macroscopic and functional changes can occur as a result of both passive and active tissue responses to the bioelectric implant.

Conclusion

A variety of chronically implantable electrodes have been developed to treat disorders of the peripheral and cranial nerves, to varying degrees of efficacy. Consideration and mitigation of detrimental effects at the neural interface with further optimization of functional nerve stimulation will facilitate the development of these technologies and translation to the clinic.

Level of Evidence

3.

Nasal septal perforation in children: Presentation, etiology, and management

OBJECTIVE

The presentation, etiology, and treatment of nasal septal perforation have been described in the adult literature; however, reports in the pediatric population are limited. In this study, we review our experience with pediatric nasal septal perforations with a focus on presentation, pathogenesis, management, and outcomes of surgical repair.

METHODS

A retrospective chart review was performed on pediatric patients diagnosed with nasal septal perforations from 1998 to 2015. Data regarding patient demographics, perforation characteristics, and treatment were extracted and analyzed.

RESULTS

Twenty-seven patients met inclusion criteria. Mean age was 10.8 years (range 2 months-17 years). Nasal crusting (n = 19, 73%) and epistaxis (n = 15, 58%) were the most common complaints at presentation. The most common etiologies were trauma (n = 9, 33%), iatrogenic sources (n = 5, 19%), and neoplasm (n = 3, 11%). Septal perforations were primarily located in the anterior septum (n = 17, 81%) and the average size was 0.9 cm (±0.37) in diameter. Four patients were managed with a nasal septal button. Successful closure was achieved in four out of six patients (66.7%) who underwent surgical repair.

CONCLUSIONS

In our series, septal perforations in children occurred most frequently due to digital nasal trauma, and crusting was the most common symptom. Factors to consider prior to repair include symptomatology, the etiology of the perforation, co-morbidities, ability to comply with post-operative care/restrictions, availability of adjacent tissue/grafts, and potential effects on nasal growth. Even with careful consideration of these factors, successful closure was limited to two-thirds of patients who were offered repair.

Comparison of treatment outcomes between intracapsular and total tonsillectomy for pediatric obstructive sleep apnea

BACKGROUND

Intracapsular tonsillectomy (IT) has been advocated as a treatment for pediatric obstructive sleep apnea (OSA). However, evidence in the literature utilizing polysomnography (PSG) is limited.

OBJECTIVE

To examine the experience at a tertiary children's hospital to evaluate the effectiveness and risks of intracapsular tonsillectomy compared to total tonsillectomy (TT) for treating pediatric OSA.

METHODS

A retrospective study was undertaken of pediatric tonsillectomy cases performed for OSA at a tertiary children's hospital from 2005 to 2010. Patients with recurrent tonsillitis, craniofacial abnormalities, chromosomal abnormalities, neuromuscular disease, and congenital malformations were excluded. Main outcome measures were apnea-hypopnea index (AHI), minimum oxygen saturation (minO₂), and surgical complications.

RESULTS

Of the 1583 patients reviewed in this study, there were 75 IT and 93 TT patients with pre- and post-operative PSG results. The IT patients were younger, had lower BMI, larger tonsil size, lower pre-operative (AHI) and lower post-operative AHI (p < 0.05). There was a similar percentage of patients that showed improvement in AHI and minimum oxygen saturation between the IT and TT groups. There were statistically similar average change in AHI and minimum oxygen saturation between the IT and TT groups at 5.6 ± 8.6 and 8.6 ± 12.9, respectively (p = 0.8) as well as similar improvement in minimum oxygen saturation between the two groups at 3.3% ± 4.3% and 3.0% ± 5.2%, respectively (p = 0.66). Of TT patients, 2.9% experienced post-operative bleeding with 1.6% requiring OR for control of hemorrhage. Of IT patients, 2.2% were found to have tonsillar regrowth with 2.0% returning to the OR for secondary tonsillectomy.

CONCLUSIONS

Intracapsular tonsillectomy, like total tonsillectomy, is effective in improving polysomnogram results in appropriately selected children. Intracapsular tonsillectomy is a suitable option for the surgical treatment of pediatric OSA consequent to its demonstrated efficacy in relieving OSA and its favorable safety profile.

Abstract P6-11-01: Cost-effectiveness of pertuzumab in HER2+ metastatic breast cancer

Purpose

The Clinical Evaluation of Pertuzumab and Trastuzumab (CLEOPATRA) study showed a 15.7-month survival benefit with the addition of pertuzumab (P) to docetaxel and trastuzumab (TH) as first-line treatment for patients with HER2 overexpressing metastatic breast cancer. We performed a cost-effectiveness analysis to assess the value of the addition of pertuzumab to docetaxel and trastuzumab.

Patient and Methods

We developed a decision-analytic Markov model to evaluate the cost-effectiveness of TH with or without P in U.S. patients with metastatic breast cancer. The model followed patients weekly over their remaining lifetimes. Health states included: stable disease, progressing disease, hospice, and death. Transition probabilities were based on the CLEOPATRA study. Costs reflected the 2014 Medicare rates. Health state utilities were the same as those used in other recent cost-effectiveness studies of trastuzumab and pertuzumab. Outcomes included health benefits expressed as discounted quality-adjusted life-years (QALYs), costs in U.S. dollars, and cost-effectiveness expressed as an incremental cost-effectiveness ratio. One-way and multi-way deterministic and probabilistic sensitivity analyses explored the effects of specific assumptions.

Results

Modeled median survival was 39.4 months (TH) and 56.9 months (THP). The addition of pertuzumab resulted in an additional 1.81 life years gained (0.62 QALYs) at a cost of $472,668 per QALY gained. Deterministic sensitivity analysis showed that THP is unlikely to be cost-effective even under the most favorable assumptions, and probabilistic sensitivity analysis predicted 0% chance of cost-effectiveness at a willingness-to-pay of $100,000 per QALY gained.

Conclusion

The addition of pertuzumab to docetaxel and trastuzumab in patients with metastatic HER2+ breast cancer is unlikely to be cost-effective in the United States.

Citation Format: Qian Y, Durkee BY, Pollom EL, King M, Dudley SA, Shaffer JB, Chang DT, Gibbs IC, Goldhaber-Fiebert JD, Horst KC. Cost-effectiveness of pertuzumab in HER2+ metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-11-01.

A child with silent sinus syndrome and spontaneous improvement after sinus surgery

Silent sinus syndrome is characterized by an asymptomatic hypoplastic maxillary sinus with progressive enophthalmos and hypoglobus. This is a disease rarely affecting children with the majority of reported cases involving adult patients. Treatment is primarily surgical with endoscopic sinus surgery to restore aeration of the sinus along with orbital reconstruction to restore facial symmetry. In this report, we describe a 7 year old child with facial asymmetry and no sinonasal symptoms. CT showed an opacified hypoplastic right maxillary sinus. One year after endoscopic sinus surgery, there was spontaneous improvement of facial asymmetry and relative maxillary sinus size.

Development of a consumer product ingredient database for chemical exposure screening and prioritization

Consumer products are a primary source of chemical exposures, yet little structured information is available on the chemical ingredients of these products and the concentrations at which ingredients are present. To address this data gap, we created a database of chemicals in consumer products using product Material Safety Data Sheets (MSDSs) publicly provided by a large retailer. The resulting database represents 1797 unique chemicals mapped to 8921 consumer products and a hierarchy of 353 consumer product "use categories" within a total of 15 top-level categories. We examine the utility of this database and discuss ways in which it will support (i) exposure screening and prioritization, (ii) generic or framework formulations for several indoor/consumer product exposure modeling initiatives, (iii) candidate chemical selection for monitoring near field exposure from proximal sources, and (iv) as activity tracers or ubiquitous exposure sources using "chemical space" map analyses. Chemicals present at high concentrations and across multiple consumer products and use categories that hold high exposure potential are identified. Our database is publicly available to serve regulators, retailers, manufacturers, and the public for predictive screening of chemicals in new and existing consumer products on the basis of exposure and risk.

Esophageal tolerance to high-dose stereotactic ablative radiotherapy

Dose-volume parameters are needed to guide the safe administration of stereotactic ablative radiotherapy (SABR). We report on esophageal tolerance to high-dose hypofractionated radiation in patients treated with SABR. Thirty-one patients with spine or lung tumors received single- or multiple-fraction SABR to targets less than 1 cm from the esophagus. End points evaluated include D(5cc) (minimum dose in Gy to 5 cm(3) of the esophagus receiving the highest dose), D(2cc) , D(1cc) , and D(max) (maximum dose to 0.01 cm(3) ). Multiple-fraction treatments were correlated using the linear quadratic and linear quadratic-linear/universal survival models. Three esophageal toxicity events occurred, including esophagitis (grade 2), tracheoesophageal fistula (grade 4-5), and esophageal perforation (grade 4-5). Chemotherapy was a cofactor in the high-grade events. The median time to development of esophageal toxicity was 4.1 months (range 0.6-6.1 months). Two of the three events occurred below a published D(5cc) threshold, all three were below a D(2cc) threshold, and one was below a D(max) threshold. We report a dosimetric analysis of incidental dose to the esophagus from SABR. High-dose hypofractionated radiotherapy led to a number of high-grade esophageal adverse events, suggesting that conservative parameters to protect the esophagus are necessary when SABR is used, especially in the setting of chemotherapy or prior radiotherapy.

Anelastic Creep Phenomena in Thin Metal Plated Cantilevers for MEMS

During the past several years, we have developed high displacement sensitivity tunneling accelerometers using surface micromachining and metal electroplating techniques. These devices consist of a Au tunneling tip fabricated below a 1-2 μm thick metal cantilever beam of electroplated Ni or Au. A thin film of e-beam evaporated Au on the underside of the cantilever serves as the tunneling counter electrode. In operation, a 100mV bias is applied across the tunneling gap. A larger turn-on voltage is also applied between the cantilever and a control electrode, located on the substrate, to deflect the cantilever and maintain a constant tunneling current of 1 or 10 nA. Typical deflections of the end of 100 μm-long and 250 μm-long cantilevers are 0.5μm during operation. We have observed that the turn-on voltage decreases over time for most devices with a larger drop observed for the Au cantilevers. In all cases, the initial decay of the turn-on voltage was almost completely recoverable after the device was turned off for 24 hrs. This decay was not found to be strongly dependent on the magnitude of the tunneling current, but could be significantly reduced by pre-stressing the cantilever before operation. Finally, a vacuum anneal at 100°C influences the measured temperature dependence of the turn-on voltage. The observed effects appear to be consistent with fatigue and creep phenomena in the cantilevers. These effects are reversible at room temperature and are dependent on the stress and temperature history of the devices. A comparison is made between metal plated and all-Si structures.

Pathological response after chemoradiation for T3 rectal cancer

OBJECTIVE

The aim of this study was to investigate the effect of preoperative chemoradiotherapy (CRT) on nodal disease in locally advanced rectal adenocarcinoma.

METHOD

Thirty-two patients staged uT3N0 and 27 patients staged uT3N1 rectal adenocarcinoma who underwent pre-CRT staging using endoscopic ultrasound or rectal protocol CT were included. The median radiation dose was 50.4 Gy (range: 45-50.4 Gy) at 1.8 Gy per fraction and all patients received concurrent 5-FU or capecitabine-based chemotherapy. Low anterior resection or abdomino-perineal resection occurred at a median of 46 days (range: 27-112 days) after CRT.

RESULTS

Eleven of 32 uT3N0 patients (34.4%) and 13 of 26 uT3N1 patients (50.0%) had ypN+ (P = 0.29). For patients with uT3N0, 10 of 20 (50.0%) with ypT2-3 and 1 of 12 (8.3%) with ypT0-1 were ypN+ (P = 0.02). For patients with uT3N1, 12 of 20 (60.0%) with ypT2-3 and 1 of 6 (16.7%) with ypT0-1 were ypN+ (P = 0.16). Overall, the ypN+ rate was 11.1% in the ypT0-yT1 group compared with 55.0% in the ypT2-yT3 group (P = 003). Among patients with uT3N0 disease, the ypN+ rate in patients who had surgery > 46 days vs<or= 46 days was 7.1%vs 55.6% (P = 0.01) respectively. Among patients with uT3N1 disease, the ypN+ rate in patients who had surgery > 46 days vs<or= 46 days was 54.5%vs 46.7%, (P = 0.99) respectively. Overall, the ypN+ rate in patients who had surgery > 46 days vs<or= 46 days was 28.0%vs 51.5% (P = 0.11).

CONCLUSIONS

The risk of residual nodal disease after CRT is significant. Primary tumour response is associated with nodal response.

Multimodality treatment with intensity modulated radiation therapy for esophageal cancer

The objective of this study is to determine the feasibility and report the outcome of patients with locally advanced esophageal cancer treated with preoperative or definitive chemoradiotherapy (CRT) using intensity-modulated radiation therapy (IMRT). Between 2003 and 2007, 30 patients with non-cervical esophageal cancer received concurrent chemotherapy and IMRT at Stanford University. Eighteen patients were planned for definitive CRT and 12 were planned for preoperative CRT. All patients had computed tomography-based treatment planning and received IMRT. The median dose delivered was 50.4 Gy. Patients planned for preoperative CRT underwent surgery 4-13 weeks (median 8.3 weeks) following completion of CRT. Median follow-up of surviving patients from start of RT was 24.2 months (range 8.2-38.3 months). The majority of tumors were adenocarcinomas (67%) and poorly differentiated (57%). Tumor location was 7% upper, 20% mid, 47% lower, and 27% gastroesophageal junction. Actuarial 2-year local-regional control (LRC) was 64%. High tumor grade was an adverse prognostic factor for LRC and overall survival (OS) (P= 0.015 and 0.012, respectively). The 2-year LRC was 83% vs. 51% for patients treated preoperatively vs. definitively (P= 0.32). The 2-year disease-free and OS were 38% and 56%, respectively. Twelve patients (40%) required feeding tube placement, and the average weight loss from baseline was 4.8%. Twelve (40%) patients experienced grade 3+ acute complications and one patient died of complications following feeding tube placement. Three patients (10%) required a treatment break. Eight patients (27%) experienced grade 3 late complications. No grade 4 complications were seen. IMRT was effective and well tolerated. Disease recurrence remains a challenge and further investigation with dose escalation to improve LRC and OS is warranted.

Lymphocyte adhesion and interactions with biomaterial adherent macrophages and foreign body giant cells

To characterize the effects of adherent macrophages and biomaterial surface chemistries on lymphocyte adhesion and activation, lymphocytes were co-cultured with monocytes alone and together, directly and separated by a porous membrane transwell on hydrophobic, hydrophilic/neutral, hydrophilic/anionic, and hydrophilic/cationic biomaterial surfaces. Surface adherent cells were quantitatively analyzed after 3 days utilizing immunofluorescence and phase contrast imaging. After periods of 3, 7, and 10 days, secreted interferon-gamma (IFN-gamma) was quantified by ELISA. Limited direct biomaterial-adherent lymphocytes were identified regardless of the presence of macrophages or foreign body giant cells (FBGC). The majority of adherent lymphocytes, which were T cells (>95%) rather than natural killer cells, predominantly interacted with adherent macrophages and FBGCs; greater than 90% were interacting on surfaces with higher levels of adherent macrophages and FBGCs and greater than 55% were interacting on surfaces with lower levels of macrophages and FBGCs. The hydrophilic/anionic surface promoted higher levels of macrophage- and FBGC-adherent lymphocytes but was nonselective for lymphocyte subtype interactions. The hydrophilic/neutral surface was selective for CD4+ T lymphocyte interactions while the hydrophobic surface was selective for CD8+ T lymphocyte interactions. IFN-gamma was produced in direct and indirect co-cultures but not in lymphocyte- and monocyte-only cultures suggesting that lymphocytes are activated via macrophage-derived cytokines rather than direct biomaterial contact. Direct lymphocyte interactions with adherent macrophages/FBGCs enhanced IFN-gamma production relative to indirect co-cultures. These results suggest that lymphocytes prefer interactions with adherent macrophages and FBGCs, resulting in lymphocyte activation, and these interactions can be influenced by biomaterial surface chemistries.

Paracrine and juxtacrine lymphocyte enhancement of adherent macrophage and foreign body giant cell activation

Lymphocytes have been shown to be involved in modulating monocyte and macrophage behavior in the foreign body reaction. Lymphocyte effects on biomaterial-adherent macrophage and foreign body giant cell (FBGC) behavior were further investigated by culturing monocytes alone or together with lymphocytes, either in direct co-cultures or indirectly in transwells, on a series of polyethylene terephthalate-based photograft co-polymerized material surfaces displaying distinct hydrophobic, hydrophilic/neutral, hydrophilic/anionic, and hydrophilic/ cationic chemistries. After periods of 3, 7, and 10 days, cytokine production was quantified by enzyme-linked immunosorbent assay and normalized to adherent macrophage/FBGC density to yield a measure of adherent macrophage/FBGC activation. Interactions with lymphocytes enhanced adherent macrophage and FBGC production of pro-inflammatory IL-1beta, TNF-alpha, IL-6, IL-8, and MIP-1beta on the hydrophobic and hydrophilic/cationic surfaces but had no effect on anti-inflammatory IL-10 production indicating lymphocytes promote a pro-inflammatory response to biomaterials. Lymphocytes also did not significantly influence MMP-9, TIMP-1, and TIMP-2 production. Interactions through indirect (paracrine) signaling showed a significant effect in enhancing adherent macrophage/FBGC activation at early time points whereas interactions via direct (juxtacrine) mechanisms dominated at later time points. Biomaterial surface chemistries differentially affected the observed responses as hydrophilic/neutral and hydrophilic/anionic surfaces, evoked the highest levels of activation relative to the other surfaces but did not facilitate lymphocyte enhancement of adherent macrophage/FBGC activation.

Lymphocyte/macrophage interactions: biomaterial surface-dependent cytokine, chemokine, and matrix protein production

The role of lymphocytes in the biological response to synthetic polymers is poorly understood despite the transient appearance of lymphocytes at the biomaterial implant site. To investigate cytokines, chemokines, and extracellular matrix (ECM) proteins produced by lymphocytes and macrophages in response to biomaterial surfaces, human peripheral blood monocytes and lymphocytes were co-cultured on polyethylene terephthalate (PET)-based material surfaces displaying distinct hydrophobic, hydrophilic/neutral, hydrophilic/anionic, and hydrophilic/cationic chemistries. Antibody array screening showed the majority of detected proteins are inflammatory mediators that guide the early inflammatory phases of wound healing. Proteomic ELISA quantification and adherent cell analysis were performed after 3, 7, and 10 days of culture. IL-2 and IFN-gamma were not detected in any co-cultures suggesting lack of lymphocyte activation. The hydrophilic/neutral surfaces increased IL-8 relative to the hydrophobic PET surface (p < 0.05). The hydrophilic/anionic surfaces promoted increased TNF-alpha over hydrophobic and cationic surfaces and increased MIP-1beta compared to hydrophobic surfaces (p < 0.05). Since enhanced macrophage fusion was observed on hydrophilic/anionic surfaces, the production of these cytokines likely plays an important role in the fusion process. The hydrophilic/cationic surface promoted IL-10 production and increased matrix metalloproteinase (MMP)-9/tissue inhibitor of MMP (TIMP) relative to hydrophilic/neutral and anionic surfaces (p < 0.05). These results suggest hydrophilic/neutral and anionic surfaces promote pro-inflammatory responses and reduced degradation of the ECM, whereas the hydrophilic/cationic surfaces induce an anti-inflammatory response and greater MMP-9/TIMP with an enhanced potential for ECM breakdown. The study also underscores the usefulness of protein arrays in assessing the role of soluble mediators in the inflammatory response to biomaterials.

Proteomic analysis and quantification of cytokines and chemokines from biomaterial surface-adherent macrophages and foreign body giant cells

Implantation of biomaterial devices results in the well-known foreign body reaction consisting of monocytes, macrophages, and foreign body giant cells (FBGCs) at the material/tissue interface. We continue to address the hypothesis that material surface chemistry modulates the phenotypic expression of these cells. Utilizing our human monocyte culture system, we have used surface-modified polymers displaying hydrophobic, hydrophilic, and/or ionic chemistries to determine the cytokines/chemokines released from biomaterial-adherent macrophages/FBGCs. This study broadens our approach by using proteomic analysis to identify important factors expressed by these cells and further quantifies these molecules with ELISAs. Proteomic profiles changed over time suggesting that the adherent macrophages underwent a phenotypic switch. Macrophage/FBGC-derived proinflammatory cytokines, IL-1beta and IL-6, decreased with time, while the anti-inflammatory cytokine, IL-10, gradually increased with time. Resolution of the inflammatory response was also demonstrated by a decrease in chemoattractant IL-8 and MIP-1beta production with time. Material-dependent macrophage/FBGC activation was analyzed using cytokine/chemokine production and cellular adhesion. Monocyte/macrophage adhesion was similar on all surfaces, except for the hydrophilic/neutral surfaces that showed a significant decrease in cellular density and minimal FBGC formation. Normalizing the ELISA data based on the adherent cell population provided cytokine/chemokine concentrations produced per cell. This analysis showed that although there were fewer cells on the hydrophilic/neutral surface, these adherent cells were further activated to produce significantly greater amounts of each cytokine/chemokine tested than the other surfaces. This study clearly presents evidence that material surface chemistry can differentially affect monocyte/macrophage/FBGC adhesion and cytokine/chemokine profiles derived from activated macrophages/FBGCs adherent to biomaterial surfaces.

Matrix metalloproteinases and their inhibitors in the foreign body reaction on biomaterials

Matrix metalloproteinases (MMPs) can degrade structural components within the extracellular matrix and at the cellular surface producing changes in cellular behavior (i.e., adhesion and migration) and subsequent pathological responses (i.e., the foreign body reaction and wound healing). We continue to study the foreign body reaction that occurs following biomaterial implantation by investigating secretory responses of biomaterial-adherent macrophages and foreign body giant cells (FBGCs) as directed by material surface chemistry and further this research by determining whether secreted MMPs play a role in macrophage adhesion and fusion. We have identified numerous MMPs and their tissue inhibitors (TIMPs) in in vitro cell-culture supernatants using antibody arrays and quantified select MMP/TIMPs with ELISAs. MMP-9 concentrations were significantly greater than both TIMP-1 and TIMP-2 on all materials. The ratios of MMP-9/TIMP-1 and MMP-9/TIMP-2 increased with time because of an increase in MMP-9 concentrations over time, while the TIMP concentrations remained constant. Total MMP-9 concentrations in the supernatants were comparable on all materials at each timepoint, while TIMP-1 and TIMP-2 concentrations tended to be greater on hydrophilic/anionic surfaces. Analysis of the MMP/TIMP quantities produced per cell revealed that the hydrophilic/neutral surfaces, which inhibited macrophage adhesion, activated the adherent macrophages/FBGCs to produce a greater quantity of MMP-9, TIMP-1, and TIMP-2 per cell. Pharmacological inhibition of MMP-1,-8,-13, and -18 reduced macrophage fusion without affecting adhesion, while inhibitors of MMP-2,-3,-9, and -12 did not affect adhesion or fusion. These findings demonstrate that material surface chemistry does modulate macrophage/FBGC-derived MMP/TIMP secretion and implicates MMP involvement in macrophage fusion.

Toward rapid high resolution in vivo intravascular MRI: evaluation of vessel wall conspicuity in a porcine model using multiple imaging protocols

PURPOSE

To assess magnetic resonance (MR) pulse sequences for high resolution intravascular imaging.

MATERIALS AND METHODS

Intravascular imaging of the abdominal aorta and iliac arteries was performed in vivo in a porcine model at 1.5 T using catheter-mounted micro-receive coils. Ten protocols, including spin-echo (SE)-echo planar imaging (SE-EPI), segmented EPI, half-Fourier single-shot turbo spin-echo (HASTE), fast imaging with steady-state free precession (TrueFISP), turbo spin-echo (TSE), and SE acquisition schemes were employed in 13 trials. Images were analyzed by six expert raters with respect to wall-conspicuity, wall-to-lumen/tissue contrast, visible layers of the arterial wall, anticipated clinical usefulness, and overall image quality. Mean differences between sequence-types were evaluated using analysis of variance (ANOVA) between groups with planned comparisons.

RESULTS

The vessel wall was delineated in almost all protocols. Motion artifacts from physiological and device motion were reduced in fast techniques. The best contrast between the wall and surrounding tissue was provided by a HASTE protocol. Anatomic layers of the vessel wall were best depicted on dark blood T2-weighted TSE. Overall, TrueFISP was ranked highest on the remaining measures.

CONCLUSION

Dedicated catheter-coils combined with fast sequences have potential for in vivo characterization of vessel walls. TrueFISP offered the best overall image quality and acquisition speed, but suffered from the inability to delineate the multiple layers of the wall, which seems associated with dark blood- and T2-weighted contrast. We believe future intra-arterial trials should proceed from this study in normal artery imaging and initially focus on fast T2-weighted dark blood techniques in trials with pathology.

Somatic mutations inVHL germline deletion kindred correlate with mild phenotype

Generally, von Hippel-Lindau (VHL) disease is caused by a germline mutation of the VHL gene (chromosome 3p), and tumorigenesis is initiated from a "second-hit" deletion. A subset of VHL patients have a germline deletion of the VHL gene, and the molecular events leading to tumorigenesis are not fully understood. To determine the molecular pathogenesis of tumor formation in this setting, we analyzed five central nervous system hemangioblastomas from three patients of a single VHL germline deletion kindred, all displaying mild clinical phenotype. Rather than loss of heterozygosity (the "second hit" in VHL germline mutation patients), all tumors from this kindred showed "second-hit" point mutations on the wild-type allele. Moreover, in two patients who each had two hemangioblastomas resected each tumor contained a unique mutation. The specific germline deletion and the overall genetic makeup of the patient did not predict these random "second-hit" point mutations. These results suggest that in patients with germline deletion of a tumor suppressor gene there is a unique genetic mechanism underlying tumorigenesis. This unique genetic mechanism correlates with and may help to understand the mild clinical phenotype seen in these patients.

Low molecular weight heparin for venous thromboembolism prophylaxis in urologic oncologic surgery

OBJECTIVES

This is a prospective study in the use of low molecular weight heparin (LMWH) for venous thromboembolism prophylaxis in the previously unstudied subset of patients undergoing elective urologic cancer surgery.

METHODS

Thirty-eight patients undergoing elective urologic surgery were studied. Thirty-six had urologic malignancies. Pre-operative risk factors for venous thromboembolic disease were recorded. All patients received LMWH (dalteparin, Fragmin; Pharmacia, Stockholm, Sweden) subcutaneously on a daily basis beginning 1-2 hr before surgery and lasting for 3-7 days. Postoperative physical examination was used to check for clinical evidence of deep venous thrombosis (DVT). Clinical parameters such as physical examination and radiological testing were used to assess for evidence of DVT. Other data included intraoperative blood loss, transfusion requirements, postoperative bleeding complications, postoperative hematocrit and coagulation profiles, and local complications related to the subcutaneous injection of the LMWH.

RESULTS

All patients completed the prophylaxis protocol. None developed DVT. Mean intraoperative blood loss was 735 mL and 12 patients received an average of 1 unit of blood transfusion. No unusual hemorrhagic events were noted intra- or post-operatively. No reactions to the LMWH were noted. Average hematocrit of postoperative day 3 was 30.7 and platelet count and coagulation profiles remained normal postoperatively.

CONCLUSIONS

Low molecular weight heparins appear promising for DVT prophylaxis in high-risk urology patients.

Reconstructive surgery for children with pelvic rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft-tissue sarcoma found in children and can arise almost anywhere skeletal muscle is found. It represents 4% to 8% of malignant solid tumors in children, ranking behind central nervous system tumors, lymphoma, neuroblastoma, and Wilms' tumor. Reconstructive surgery has become an integral part of the total plan in patients undergoing radical surgery for rhabdomyosarcoma. Advances in surgical techniques can often provide a reasonable lifestyle for patients.

Nonobstetrical abdominal surgery during pregnancy in Women's Hospital

OBJECTIVE

To determine if nonobstetrical abdominal surgery during pregnancy in Women's Hospital at the University of Southern California School of Medicine was associated with increased rates of preterm delivery or spontaneous loss. Preoperative diagnostic accuracy was also evaluated.

METHODS

We performed a retrospective review of all cases of nonobstetrical abdominal surgery in our institution during a 7-year period from November 1991 to November 1998.

RESULTS

One hundred-six cases of nonobstetrical abdominal surgery were identified. Eighty-eight women underwent laparotomy and 18 had laparoscopic abdominal surgery. Seventy-three women had emergent surgery and 31 had elective surgery. Seventy-six percent (80/106) of subjects had the same preoperative and postoperative diagnoses. We obtained delivery data for 62 of 106 (59%) subjects. Eleven of 62 (18%) subjects who had nonobstetrical abdominal surgery during pregnancy delivered preterm (<37 weeks' gestation). This was not significantly different from the institutional preterm delivery rate of Women's Hospital (8999/56305 [16%]) (P = 0.84). Two of 106 (2%) women experienced spontaneous pregnancy loss following surgery; both occurred in the second trimester.

CONCLUSIONS

Nonobstetrical abdominal surgery during pregnancy in Women's Hospital was not associated with higher frequencies of preterm deliveries or spontaneous losses than our institutional rates.

Use of a laparoscopic insufflation port for ileal conduit endoscopy

We present an effective and simple technique for performing endoscopy of an ileal conduit. With a laparoscopic insufflation port in the stoma, a flexible cystoscope or ureteroscope can be inserted. The one-way valve of the port prevents leakage of irrigation fluid and allows the conduit to distend for optimal visualization. This technique is particularly useful when access to the upper urinary tracts is needed.

Declining sperm counts in the United States? A critical review

PURPOSE

Recent reports suggest declining sperm counts in the United States. These reports did not include all available data and did not account for geographic variations noted in prior studies. We examined all available data on U.S. sperm counts and evaluated whether geographic variations account for the decline suggested.

MATERIALS AND METHODS

We reviewed all 29 U.S. studies from 1938 to 1996 reporting manually counted semen analyses of 9,612 fertile or presumably fertile men. We determined mean sperm concentrations by geographic location with weighted analysis of variance, and assessed any changes with time by linear regression analysis.

RESULTS

Mean sperm concentrations from New York were significantly higher than from all other U.S. cities (98.6 versus 71.6 x 10(6) sperm per cc, respectively, p = 0.006). There has been no statistically significant change with time for mean sperm concentrations reported from New York (p = 0.49) or from U.S. cities other than New York (p = 0.62). Analysis without separating by location revealed a decline (p = 0.047).

CONCLUSIONS

Sperm concentrations are highest in New York compared to other U.S. cities. When accounting for this geographic difference and examining all available data, there appears to be no significant change in sperm counts in the U.S. during the last 60 years. Further studies addressing the causes of geographic variations are needed.

Vaginal reconstruction

Absence of the vagina presents a challenging problem for the reconstructive urologist. This article reviews the pertinent diagnostic and pretreatment considerations and the surgical options, in particular, bowel vaginoplasty, for these patients.

Transurethral cystotomy repair

We present a novel transurethral technique for cystotomy repair. This method can be used for immediate bladder repair following limited bladder injury and avoids the morbidity associated with laparotomy.

Rapid reduction in blood flow to the rat ventral prostate gland after castration: preliminary evidence that androgens influence prostate size by regulating blood flow to the prostate gland and prostatic endothelial cell survival

BACKGROUND

Androgenic steroids regulate the development and size of the mammalian prostate gland. The mechanism(s) for this growth control might involve a direct effect on prostate cell proliferation and survival as well as more complex effects on the tissue environment supporting nourishment and oxygenation. In this study, we evaluated an animal model of androgen action on the prostate, the rat ventral prostate gland, to determine whether acute androgen withdrawal, by means of castration, might alter the primary blood flow to the prostate gland and for the effects of castration on prostatic endothelial cell viability.

METHODS

Groups of rats studied included intact control males, males that had been surgically castrated, or males that received a sham-surgical castration. Relative blood flow (RBF) to the rat ventral prostate glands and rat bladders were measured at 18 and 24 hr after castration or sham castration using a fluorescent microsphere infusion technique. Thin sections from fixed and embedded rat ventral prostate glands obtained from unoperated or 12-hr castrated rats were analyzed by the TUNEL immunostaining technique to microscopically identify and quantify apoptotic epithelial, stromal, and endothelial cells.

RESULTS

RBF to the rat ventral prostate was reduced by 38%, at 18 hr after castration when compared with intact or sham-operated rats and by 45% at 24 hr after castration (P=0.038 unoperated/0.025 sham operated). In contrast, RBF to the bladder was not significantly different between any of the groups in the 24-hr castrate experiment. TUNEL staining analysis of ventral prostate tissues obtained from 12-hr castrated rats showed only rare TUNEL-positive epithelial cells similar to the control tissue but significantly increased TUNEL labeling for endothelial and other ventral prostate stromal cells.

CONCLUSIONS

Castration resulted in a rapid and significant reduction of blood flow to the mature rat ventral prostate gland that was not seen in the bladder. This reduction precedes the appearance of apoptosis in the epithelial cells of the tissue but more coincided with the appearance of TUNEL-positive prostate vascular endothelial and stromal cells, suggesting that androgens support the survival of cells in the vascular and stromal compartment of the rat prostate as well as in the prostatic epithelium. These preliminary data support the concept that androgen action on the prostate might involve primary regulation of prostate blood flow and prostate vascular cell vitality.

The Malone antegrade continence enema procedure in the management of patients with spina bifida

BACKGROUND

In patients with spina bifida, traditional bowel management programs such as suppositories, retrograde enemas, and manual disimpaction have been largely unsatisfactory. The Malone antegrade continence enema (ACE) procedure has largely changed our approach to bowel management in this patient group.

STUDY DESIGN

Over a 3-year period between January 1994 and January 1997, 27 patients with spina bifida underwent the Malone ACE procedure at our institutions. At the time of their ACE procedure, four patients underwent simultaneous continent urinary diversion and three had simultaneous small-bowel bladder augmentation. All the patients were evaluated for 9 months or more after their procedure, and 10 of the patients have been followed for more than 2 years.

RESULTS

Postoperatively, predictable bowel control and continence were achieved in 19 of the 27 patients, but 6 had some rectal soiling requiring a sanitary pad. All patients were out of diapers and none reported stomal leakage. Eighteen of the 27 patients were able to manage independently and 9 required assistance. Two patients had stopped using their ACE stoma despite good technical results. The appendix was used as a catheterizable stoma in 15 of the 27 patients. The appendix was not available in 12 patients, so a tubularized cecal flap was used in 9 and a small-bowel neoappendix was created in 3. Complications included stomal stenosis in 5 patients, cecal-flap necrosis in 1, and stomal granulations in 3.

CONCLUSIONS

We believe that the ACE procedure provides reliable colonic emptying and avoids fecal soiling in the majority of individuals, and we find it widely and enthusiastically accepted by patients with spina bifida.

Hypospadias repair by laser tissue soldering: intraoperative results and follow-up in 30 children

OBJECTIVES

We examined the use of laser tissue soldering (LTS) as an adjunct to suturing of, as well as a primary means of, tissue closure in urethral reconstruction.

METHODS

Since June 1994, 26 boys ranging in age from 3 months to 14 years (mean 3.0 years) underwent hypospadias repair using LTS techniques. The classification of hypospadias was subcoronal in 13, midpenile in 5, penoscrotal in 7, and scrotal in 1. Laser tissue soldering was used in an additional 4 patients: tunica vaginalis patch graft corporoplasty in 2 (scrotal hypospadias), epispadias fistulae in 1, and urethral diverticulum in 1. Of these cases, 3 hypospadias repairs were completely sutureless. An intraoperative comparision was made between suturing and LTS with respect to operative time and degree of difficulty in performing LTS. Postoperatively, patients were examined to determine complications, including stricture, fistula, or impaired wound healing. An unselected group of 25 consecutive boys undergoing hypospadias repair between 1991 and 1992 served as a historical control group.

RESULTS

No intraoperative complications resulted from laser activation. In 5 of the 30 procedures (16.6%), suture disruption was noted to occur, with a higher incidence seen with finer, dyed suture material. For hypospadias repair, the average time to suture was 6.7 min/cm (n = 23), whereas it was 3.1 min/cm for adjunctive LTS (n = 23) and 1.4 min/cm for sutureless urethroplasty (n = 3). Follow-up ranged from 3 to 22 months (average 9.6). Four fistulae were noted (1 onlay, 2 skin tube grafts, 1 Thiersch tube) each following penoscrotal or scrotal hypospadias repair; a fifth fistula developed following a traumatic catheterization in a sutureless repair. The overall complication rate in the LTS group was 19% (5 of 26) versus 24% (6 of 25) for controls, whereas that for the distal forms of hypospadias was 11% (2 of 18) and 13.6% (3 of 22), respectively.

CONCLUSIONS

Tissue soldering with laser and chromophore-doped solder is feasible, safe, and easy to perform. Laser tissue soldering may be an alternative to standard microsuture technique for hypospadias repair.

Overexpression of a Rrp1 transgene reduces the somatic mutation and recombination frequency induced by oxidative DNA damage in Drosophila melanogaster

Recombination repair protein 1 (Rrp1) includes a C-terminal region homologous to several DNA repair proteins, including Escherichia coli exonuclease III and human APE, that repair oxidative and alkylation damage to DNA. The nuclease activities of Rrp1 include apurinic/apyrimidinic endonuclease, 3'-phosphodiesterase, 3'-phosphatase, and 3'-exonuclease. As shown previously, the C-terminal nuclease region of Rrp1 is sufficient to repair oxidative- and alkylation-induced DNA damage in repair-deficient E. coli mutants. DNA strand-transfer and single-stranded DNA renaturation activities are associated with the unique N-terminal region of Rrp1, which suggests possible additional functions that include recombinational repair or homologous recombination. By using the Drosophila w/w+ mosaic eye system, which detects loss of heterozygosity as changes in eye pigmentation, somatic mutation and recombination frequencies were determined in transgenic flies overexpressing wild-type Rrp1 protein from a heat-shock-inducible transgene. A large decrease in mosaic clone frequency is observed when Rrp1 overexpression precedes treatment with gamma-rays, bleomycin, or paraquat. In contrast, Rrp1 overexpression does not alter the spot frequency after treatment with the alkylating agents methyl methanesulfonate or methyl nitrosourea. A reduction in mosaic clone frequency depends on the expression of the Rrp1 transgene and on the nature of the induced DNA damage. These data suggest a lesion-specific involvement of Rrp1 in the repair of oxidative DNA damage.

Effects of diode laser welding with dye-enhanced glue on tensile strength of sutures commonly used in urology

BACKGROUND AND OBJECTIVE

Tissue welding using laser-activated protein solders may soon become an alternative to sutured tissue approximation. In most cases, approximating sutures are used both to align tissue edges and provide added tensile strength. Collateral thermal injury, however, may cause disruption of tissue alignment and weaken the tensile strength of sutures. The objective of this study was to evaluate the effect of laser welding on the tensile strength of suture materials used in urologic surgery.

STUDY DESIGN/MATERIAL AND METHODS

Eleven types of sutures were exposed to diode laser energy (power density = 15.9 W/cm2) for 10, 30, and 60 seconds. Each suture was compared with and without the addition of dye-enhanced albumin-based solder. After exposure, each suture material was strained (2"/min) until ultimate breakage on a tensometer and compared to untreated sutures using ANOVA.

RESULTS

The strength of undyed sutures were not significantly affected; however, violet and green-dyed sutures were in general weakened by laser exposure in the presence of dye-enhanced glue. Laser activation of the smallest caliber, dyed sutures (7-0) in the presence of glue caused the most significant loss of tensile strength of all sutures tested.

CONCLUSION

These results indicate that the thermal effects of laser welding using our technique decrease the tensile strength of dyed sutures. A thermally resistant suture material (undyed or clear) may prevent disruption of wounds closed by laser welding techniques.

Laser welding with albumin-based solder: experimental full-tubed skin graft urethroplasty

BACKGROUND AND OBJECTIVES

Fistula and stricture formation at the site of sutured anastomoses are frequent complications of major urethroplasty. We performed urethroplasty using laser-welded skin tube grafts in the hope that in addition to being free of suture holes, grafts would be as strong as or stronger than sutured controls.

STUDY DESIGN/MATERIAL AND METHODS

Scrotal skin was harvested from each of 11 rabbits and fashioned into tubes 3-4 cm in length using either conventional suture techniques or laser welding. Welding was performed using an 808-nm diode laser and a dye-enhanced solder composed of albumin and sodium hyaluronate. Laser power density was 15.9 watts/cm2. For each graft, leak pressure, and urethroplasty time (tube creation and anastomosis to native urethra) were measured.

RESULTS

Urethroplasty time was significantly shorter and initial leak pressures were seven times greater in the laser-welded group.

CONCLUSIONS

The near-uniform occurrence of strictures in both groups suggests that the rabbit is not an ideal model for free tube graft urethroplasty. However, our data indicate that laser welding with albumin-based solder, when used in the appropriate setting, may offer the potential for the rapid creation of watertight grafts in reconstructive urology.

Laser tissue soldering in urinary tract reconstruction: first human experience

OBJECTIVES

Laser tissue soldering (LTS) in the urinary tract provides an immediate leak-free seal and may avoid complications seen with conventional repair (such as fistula and stricture). We have begun a Phase I clinical trial investigating the use of LTS in performing urologic reconstructive surgery.

METHODS

Ten patients (aged 3 months to 38 years) underwent urologic reconstruction using LTS with a protein solder composed of human albumin (42%) and indocyanine green dye. In each case standard microsuture repair preceded laser-soldered suture line reinforcement. Anastomotic closure time and immediate leak pressure were measured. Postoperatively, all patients were evaluated for evidence of complications, including stricture, fistula formation, or impaired healing.

RESULTS

Using LTS as an adjunct to suturing added an average of 7.9 +/- 3.0 minutes (28%) to the overall mean anastomotic time of 28.3 +/- 9.4 minutes. Intraoperative leak pressure measurements for laser-soldered anastomoses (> or = 94.2 +/- 24.2 mm Hg) were significantly higher (P < 0.001) than primarily sutured anastomoses (20 +/- 2.9 mm Hg). Two instances of suture disruption (20%) occurred during laser activation, neither of which were repaired with sutures. Average follow-up for all patients was 7.1 + - 2.2 months. There were no intraoperative or postoperative complications, including the 2 patients with suture disruption.

CONCLUSIONS

These initial clinical results indicate that LTS is safe, easy to perform, and, contrary to conventional suturing, provides an immediate leak-free closure. Follow-up in these and other patients, as well as those undergoing sutureless and stent-free procedures, will determine whether our method of LTS benefits patients undergoing urologic reconstruction.

Laser welding versus suturing in tunica vaginalis and venous patch graft corporoplasty

Congenital penile curvature may result from corporeal disproportion in nearly 40% of cases, while in adults scarring of the corporeal bodies or periurethral fibrosis accounts for the majority of cases. Some surgeons advocate lengthening the fibrosed corporeal bodies by excising tunica albuginea and grafting such defects to straighten the penis. Tunica vaginalis, dermis, dorsal vein and lyophilized dura have been used for this purpose. Traditionally, these graft biomaterials have been sutured to the tunica albuginea. We assessed the feasibility, short-term safety and efficacy of diode laser tissue welding using albumin based solder and indocyanine green dye to perform patch graft corporoplasty in the dog. Ten animals were subjected to bilateral transverse excision of 1 x 2 cm. sections of tunica albuginea. Corporoplasty was performed using grafts composed of saphenous vein (5) or tunica vaginalis (5). Microsurgical repair with 7-zero polydioxanone suture (10) was compared to contralateral laser welded repair (10) by recording operative time, initial and short-term bursting pressures (mean plus or minus standard deviation) and histological analysis. Operative time on the laser side (9.8 +/- 2.3 minutes) was significantly shorter (p < 0.05) than on the suture side (17.1 +/- 5.1 minutes). Leak pressures, initially (laser 105.7 +/- 23.8 mm. Hg versus suture 35.3 +/- 8.0 mm. Hg), at 3 to 5 days (greater than 333.3 +/- 62.4 mm. Hg versus 136.6 +/- 39.4 mm. Hg) and at 7 to 10 days (greater than 397.8 +/- 39.8 mm. Hg versus 191.5 +/- 46.4 mm. Hg) were higher (p < 0.05) in the laser side compared to controls. Graft failure (necrosis) occurred in 3 repairs (2 laser on day 4 and 1 suture on day 10). Viable tissue with minimal differences in foreign body reaction between groups was observed in the remaining grafts. We conclude that laser welded patch graft corporoplasty using tunica vaginalis or vein is easy to perform, and provides excellent initial and short-term leak pressures. The use of laser welding in conjunction with suturing may be beneficial in corporoplasty for congenital or acquired penile curvature.

Limb-patterning activity and restricted posterior localization of the amino-terminal product of Sonic hedgehog cleavage

BACKGROUND

Sonic hedgehog (Shh), a vertebrate homolog of the Drosophila segment polarity gene hedgehog (hh), has been implicated in patterning of the developing chick limb. Such a role is suggested by the restricted expression of Shh along the posterior limb bud margin, and by the observation that heterologous cells expressing Shh have limb-polarizing activity resembling that of cells from the polarizing region of the posterior limb bud margin. It has not been demonstrated, however, that the Sonic hedgehog protein (SHH) alone is sufficient for limb patterning. SHH has been shown to undergo autoproteolytic cleavage in vitro, yielding two smaller products. It is of interest, therefore, to determine whether processing of SHH occurs in the developing limb and how such processing influences the function of SHH.

RESULTS

We demonstrate that SHH is proteolytically processed in developing chick limbs. Grafts of cells expressing SHH protein variants that correspond to individual cleavage products demonstrate that the ability to induce patterned gene expression and to impose morphological pattern upon the limb bud is limited to the amino-terminal product (SHH-N) of SHH proteolytic cleavage. We also demonstrate that bacterially synthesized and purified SHH-N, released from implanted beads, is sufficient for limb-patterning activity. Finally, we show that the endogenous amino-terminal cleavage product is tightly localized to the posterior margin of the limb bud.

CONCLUSIONS

Our data show that, of the two cleavage products resulting from SHH autoproteolysis, SHH-N expressed in grafted heterologous cells or supplied in purified form is sufficient to impose pattern upon the developing limb. Moreover, the restricted localization of the endogenous amino-terminal SHH cleavage product to the posterior border of the chick limb bud makes it unlikely that its patterning activity results from it being distributed in a broad gradient across the antero-posterior axis. More consistent with the observed localization is a model in which the amino-terminal SHH cleavage product exerts its patterning effects by local induction in or near the polarizing region, initiating a cascade of gene expression that ultimately extends across the developing limb.

Long-range sclerotome induction by sonic hedgehog: direct role of the amino-terminal cleavage product and modulation by the cyclic AMP signaling pathway

A long-range signal encoded by the Sonic hedgehog (Shh) gene has been implicated as the ventral patterning influence from the notochord that induces sclerotome and represses dermomyotome in somite differentiation. Long-range effects of hedgehog (hh) signaling have been suggested to result either from local induction of a secondary diffusible signal or from the direct action of the highly diffusible carboxy-terminal product of HH autoproteolytic cleavage. Here we provide evidence that the long-range somite patterning effects of SHH are instead mediated by a direct action of the amino-terminal cleavage product. We also show that pharmacological manipulations to increase the activity of cyclic AMP-dependent protein kinase A can selectively antagonize the effects of the amino-terminal cleavage product. Our results support the operation of a single evolutionarily conserved signaling pathway for both local and direct long-range inductive actions of HH family members.

Floor plate and motor neuron induction by different concentrations of the amino-terminal cleavage product of sonic hedgehog autoproteolysis

The differentiation of floor plate cells and motor neurons can be induced by Sonic hedgehog (SHH), a secreted signaling protein that undergoes autoproteolytic cleavage to generate amino- and carboxy-terminal products. We have found that both floor plate cells and motor neurons are induced by the amino-terminal cleavage product of SHH (SHH-N). The threshold concentration of SHH-N required for motor neuron induction is about 5-fold lower than that required for floor plate induction. Higher concentrations of SHH-N can induce floor plate cells at the expense of motor neuron differentiation. Our results suggest that the induction of floor plate cells and motor neurons by the notochord in vivo is mediated by exposure of neural plate cells to different concentrations of the amino-terminal product of SHH autoproteolytic cleavage.