Evaluation of Treatment Interruptions and Recovery during Biology-Guided Radiotherapy Delivery

PURPOSE/OBJECTIVE(S)

A Biology-guided Radiotherapy (BgRT) based device is designed to use Positron Emission Tomography (PET) signals to achieve tracked dose delivery. The goal of this study is to investigate the dose delivery accuracy in case of interruption during BgRT treatment, and resumption in a separate treatment session for a multi-target delivery, as the PET activity continues to decay.

MATERIALS/METHODS

A custom-built large anthropomorphic phantom (LAP) including a 26 mm spherical target with 3D independent motion and two 22 mm spherical targets with 1D sinusoidal motion embedded in water was used. All three targets were filled with FGD in an 8:1 target to background uptake ratio (41.52 kBq/ml in target and 5.19 kBq/ml in background). During BgRT delivery, the treatment was intentionally paused during delivery to the second target and the current treatment session was ended to generate a partial fraction. Then the partial fraction was continued in a new session, where the CT scan localization and PET pre-scan were repeated using the existing PET activity present in the phantom. The newly acquired PET pre-scan, was then used to determine if sufficient PET counts were present to resume treatment delivery. The interruption and recovery algorithm is designed to calculate the fluence that needs to be delivered to the remaining targets as well as the residual fluence to be given to the targets that have already received partial dose prior to the interruption. Once the new fluence is recomputed, the treatment is resumed. The delivered doses were captured using radiochromic film (EBT-XD) inserted in the target as well as post-treatment dose calculations based on the delivered beamlet sequence to evaluate the results in terms of dosimetric coverage and margin loss. The margin loss is calculated as the maximum difference between the distance from the Clinical Target Volume (CTV) contour to the 97% isodose contour in the treatment plan and the on the film. The dosimetric coverage is defined as the percentage of voxels within the CTV that lies within 97% and 130% of the prescribed dose.

RESULTS

As shown in the table below, a margin loss of less than 3 mm for all targets and 100% CTV coverage was achieved. After treatment interruptions, the PET safety evaluation based on the PET pre-scan helped to determine whether the treatment could be continued on the same day using the same injected PET activity (an NTS value ≧ 2 and AC value ≧ 5 kBq/ml).

CONCLUSION

This study demonstrated that the BgRT system is able to deliver the prescribed dose to all targets with independent motion, even when an interruption and resumption occurs during treatment. In case such an interruption if the remaining PET activity satisfies the BgRT safety evaluation, the treatment can continue to deliver the remainder of the BgRT doses.

Intrafraction Dosimetric Evaluation of Biology-Guided Radiotherapy to a Target Under Respiratory Motion

PURPOSE/OBJECTIVE(S)

To evaluate the reproducibility and variability of biology-guided radiotherapy (BgRT) treatments using a large anthropomorphic phantom modeling the motion amplitude of a lung tumor.

MATERIALS/METHODS

RefleXion X1 is equipped with two opposing 90 degrees PET detector arcs to capture the radionuclide emissions and direct the 6MV Linac to treat the lesions in real time. A custom-built phantom filled with a liquid [¹⁸F]Fluorodeoxyglucose (FDG) solution was used. Fillable target and OAR structures were 3D printed and attached to motion stages. The GTV = CTV was matched to the spherical 22 mm diameter target, and the PTV was a 5 mm expansion from the CTV volume. The Biology Tracking Zone (BTZ) was generated after adding 5 mm margin to the motion extent of the CTV. The OAR was a large C-shape annulus (emulating a heart) that was approximately 3 cm from the target. The 3D independent motion trajectory of the target was designed to mimic lung motion: range of +5.8 mm to -4.9 mm in LR, range of +14.4 mm to -11.3 mm in SI, and range of +5.2 mm to -5.1 mm in AP directions. The OAR motion waveform used a 1D sinusoidal pattern with a 5 mm amplitude in SI direction. The target and the OAR were filled with 40 kBq/mL while the background had 5 kBq/mL FDG. A BgRT Modeling (imaging-only) PET acquisition was performed using RefleXion X1 and used to generate a 4-fraction BgRT treatment plan prescribing 10 Gy/fraction to PTV. For each delivery, target, OAR and background were filled with the same FDG concentrations as in the BgRT Modeling PET planning scan. Dosimetry to the target and OAR were both measured using an ion-chamber (Exradin A14SL) and film in the coronal plane through the center of the GTV for all 4 fractions.

RESULTS

The mean activity concentration within the (BTZ) was 7.4 ± 0.8 kBq/mL. The calculated signal-to-noise ratio metric (Normalized Target Signal) within the BTZ was 4.0 ± 0.3. Total treatment times were all less than 35 minutes (34.3 ± 0.2). Prescription dose coverage to the CTV for all 4 fractions was 100%. Ion chamber measurements in the CTV were -1.6 ± 1.3% relative to the planned dose over the active area of the ion-chamber. Minimum and maximum doses to the CTV, measured on film, were -7.7 ± 2.2% and 1.3 ± 1.4%, calculated relative to the planned dose distribution, respectively. The OAR maximum point dose measured on film was -8.7 ± 2.9%, calculated relative to the maximum OAR dose predicted on the bounded dose-volume histogram.

CONCLUSION

Based on this initial study, accurate and reproducible dosimetry can be achieved for targets under respiratory motion using biology-guided radiotherapy over the course of a complete course of treatment. Further studies are needed to evaluate the intrafraction dosimetry of BgRT delivery under various motion models and tumor sizes.

Decay Series Dose Delivery Validation of a Biology-Guided Radiotherapy (BgRT) Methodology

PURPOSE/OBJECTIVE(S)

In this work, we compared the accuracy between the planned dose estimated by a commercial BgRT treatment planning system to the measured delivered dose by the BgRT treatment delivery device. The dose delivered was measured with the Sun Nuclear ArcCHECK device containing a customized phantom filled with fluorodeoxyglucose F18 (FDG) with a fixed target to background activity concentration ratio. The BgRT approach was evaluated for its capacity to accurately deliver a planned dose to a phantom target of an increasingly limited PET signal due to radioactive decay.

MATERIALS/METHODS

The Sun Nuclear ArcCHECK is a helical detector assembly of 1,386 diodes around a 15 cm diameter cavity designed for quality assurance of linear accelerator (LINAC) driven therapies. In this work, the ArcCHECK was loaded with a cylindrical phantom containing a 22 mm diameter homogenous ball and a C-shape insert. The ball target was designated as an organ at risk (OAR) with appropriate dose constraints applied, and the C-shaped insert was designated as the target. The C-shaped target was used to simulate a tumor with a necrotic core. A cylindrical planning/gross tumor volume was placed around the C-shape, providing a test case of delivery to a partially PET-avid target. The target and OAR were filled with 58.46 kBq/mL of FDG and the background with 7.30 kBq/mL, giving an approximate target to background ratio of 8:1. A kVCT localization scan, a short PET pre-treatment scan, and a LINAC treatment sequence (1000 cGy per fraction) were performed each run with four runs performed over a duration of ∼3.5 hours (1.9 half-lives). The ArcCHECK measured the delivered dose during each LINAC treatment sequence and compared it to the plan predicted dose. The relative dose (RD) and absolute dose (AD) gamma values were then calculated for each run using Sun Nuclear's proprietary software with a gamma pass rate criterion of 3mm/3%.

RESULTS

The PET scans for runs 1-4 were completed with background activity concentrations of 5.49 kBq/ml, 3.95 kBq/ml, 2.79 kBq/ml, and 2.02 kBq/ml, respectively. The scans further reported 17.48 kBq/ml, 12.26 kBq/ml, 7.93 kBq/ml, and 6.95 kBq/ml as the mean activity concentrations for the cylindrical gross tumor volume of the planned treatment. After treatment delivery, the resulting RD gamma values were 98%, 94%, 93%, and 95% and AD gamma values were 98%, 93%, 92%, and 94% for runs 1-4.

CONCLUSION

Results from this study demonstrated treatment delivery stability with consistent repeatability in the 8:1 target to background contrast condition even with diminishing PET signal from the phantom target as the activity decayed. This work shows that BgRT is capable of delivering to a cylindrical target volume that is very different from the PET avid C-shaped that was used for the plan and delivery.

Dosimetric Accuracy of Multi-Target Biology-Guided Radiotherapy Treatments in a Single Session

PURPOSE/OBJECTIVE(S)

We present the first dosimetric measurements of single session, multi-target BgRT deliveries using a clinically realistic motion phantom on a research-only version of the RefleXion X1 system.

MATERIALS/METHODS

A custom-made anthropomorphic phantom of a human torso with embedded fillable targets mimicking 18F-FDG-avid lesions was used. From the three embedded spherical targets, Target 1 was 26 mm in diameter coupled with a 3D independent respiratory motion with 22 mm range, whereas Target 2 and 3 were 22 mm in diameter and moved with a 1D 5 mm maximum sinusoidal motion. The 18F-FDG concentration in the background cavity of the phantom was 5 kBq/ml, and the targets were loaded with 10:1, 8:1 and 6:1 contrast relative to the background for Targets 1, 2, 3, respectively. Spherical structures were contoured as GTVs (CTV = GTV) and a 5 mm margin was added to create PTVs. Motion extent of the tumors were captured to create biological tracking zones for each target. Treatment plans were generated using a research version of the Reflexion treatment planning software to deliver 8 Gy/fx to the PTVs. The treatment delivery was repeated 2 times, and each time the phantom was refilled according to the plan. PET image evaluation metrics for each of the three targets were also recorded. Target dosimetry was measured using a combination of radiographic film and ion chamber. The maximum distance between the 97% prescription isodose line from the plan and the film measurements was used to characterize the dosimetric accuracy of the tracked deliveries. CTV and PTV min, max, and mean doses measured on film were also recorded for each target.

RESULTS

Treatment plans were successfully created with 100% prescription dose coverage to each target loaded with different FDG ratios. Total treatment times for the single-plan, three-target deliveries were less than 80 minutes. PET evaluation metrics at imaging-only and pre-scan, and planning and film dosimetry to the GTV and PTV for each of the three targets is shown in table below (mean ± standard deviation of both deliveries). The CTV dose coverage was maintained for all targets. The shrinkage distance of the 97% prescription dose isodose line on the film plane for all three targets was less than 3 mm for both tests, and ranged from -0.4 to -2.34 mm.

CONCLUSION

These results demonstrate that high tracking accuracy and dosimetric accuracy can be achieved in single session, multi-target deliveries over a range of target-to-background 18F-FDG concentrations and target motion patterns.

Treatment Plan Creation and Delivery with and without BgRT for Static and Motion Trajectories

PURPOSE/OBJECTIVE(S)

In this work we try to validate the motion tracking capabilities of BgRT for periodic and step motion trajectories. SBRT plans that matches the corresponding BgRT plans are created and delivered to the same phantom with and without motion and results are evaluated. Using BgRT based SBRT plans eliminates any user bias and creates SBRT plans that would represent treatment delivery scenarios that could have happened if the PET guided BgRT was not present for that treatment.

MATERIALS/METHODS

To validate SBRT plans that matches the BgRT plans, we used three different types of motion patterns (1) static, (2) lung tumor motion and (3) one-centimeter step-shift. The lung tumor motion (∼25 mm in IEC-Y, ∼7 mm in IEC-X and ∼ 10 mm in IEC-Z) was used as it represents a continuous motion of the target for the entire length of the study while the step-shift case corresponds to the patient or tumor shifting between the localization CT and the start of treatment. First, a 10 Gy per fraction BgRT plan was created for each of the three experiments based on the corresponding PET image. Then, the BgRT plans were delivered to the corresponding targets with and without motion and results are evaluated. To perform a comparative study that assess the performance of BgRT and traditional SBRT (planning and delivery methods), the exact same plan fluence of BgRT plan for each experiment was used to create the corresponding SBRT plans. The newly created SBRT plans were delivered to the corresponding phantom experiments and were compared against BgRT delivery in terms of dose coverage and target margin loss using radiochromic film that moves with the target. The margin loss was calculated as the difference between the distance from the CTV contour to the 97% isodose contour in the treatment plan and the CTV contour to the 97% isodose contour on the film. Dosimetric coverage was on the other hand calculated as the percentage of the voxels within the CTV that lies within 97% and 130% of the prescribed dose.

RESULTS

The results showed that the margin loss for BgRT is less than 3 mm, while for the SBRT plans were more than 3 mm when target motion is present. The dosimetric coverage for BgRT was 100% for all three cases, however less than 100% for the SBRT cases with motion. Table showing margin loss for the various experiments for a prescription dose of 10 Gy.

CONCLUSION

The results shows that BgRT is capable of tracking the tumor motion and delivering the prescribed dose to the moving target.

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.

Characterization of Biology-Guided Radiotherapy Accuracy as a Function of PET Tracer Uptake

PURPOSE/OBJECTIVE(S)

To characterize the tracking capability and dosimetric accuracy of biology-guided radiotherapy (BgRT) under clinically relevant PET tracer uptake scenarios relative to the background.

MATERIALS/METHODS

A custom-made anthropomorphic phantom filled with a liquid 18F-FDG solution including two embedded fillable 22 mm diameter spherical structures mimicking GTV (= CTV) and OAR was coupled to motion stages to create an independent 3D respiratory motion with 22 mm maximum range for target and a 5 mm 1D sinusoidal motion in the OAR. The biology-tracking zone (BTZ) was generated by adding 5 mm margin to the motion extent. The three BgRT scenarios studied were representative of tumors with good (8:1), borderline (4:1) and undesired (2:1) PET biodistributions compared to background. The clinical safety limit of BgRT uses Activity Concentration within the BTZ (AC ≥ 5 kBq/ml) and Normalized Target Signal as a contrast metric (NTS ≧ 2.7 for planning and ≧ 2 for delivery). The BgRT deliveries were repeated 3 times with radiochromic film and integrated ion chamber capturing the target and OAR doses. Tracked dosimetry was assessed using a margin-loss calculation defined as the maximum linear difference in distance between the planned and delivered 97% prescription iso-dose lines.

RESULTS

The imaging-only PET images used to create BgRT plans had an AC of 7.0, 5.3, and 1.6 kBq/ml with an NTS of 6.8, 5.3, and 1.8 for 8:1, 4:1, and 2:1 concentrations, respectively. Qualitatively, the target was not visible on the planning PET images 2:1 loading scenario. At delivery, the mean pre-scan activity concentrations were 6.8, 4.7, and 3.7 kBq/ml with corresponding mean NTS of 3.7, 2.6, 1.5 for 8:1, 4:1 and 2:1 deliveries. The pre-scan values of AC or NTS did not satisfy the clinical system safety limits for 4:1 and 2:1 ratio experiments, but the engineering software allowed for the delivery to capture the resulting doses. The deliveries showed a prescription dose coverage to the CTV of 100% for the 8:1 and 4:1 cases, but 88% for the 2:1 case. When compared to the planned dose values, the delivered minimum doses were -7.6%, -8.6% and -10.9%, whereas the maximum dose differences in CTV were 1.2%, 0% and -4.8% of the planned dose distributions of the 8:1, 4:1 and 2:1 cases, respectively. Calculated margin losses were -2.3, -3.8, and -5.5 mm, for the 8:1, 4:1, and 2:1 cases, respectively. The maximum OAR doses were less than the maximum doses predicted on the bounded DVH curves for all scenarios.

CONCLUSION

With sufficient tracer uptake in the target, BgRT can deliver tracked dosimetry for targets with a large respiratory motion profile. Both the good BgRT candidate and borderline cases produced clinically acceptable delivered doses, even though the borderline case was flagged by the clinical system safety checks. As expected, the delivered BgRT dose distributions were suboptimal with reduced tumor over background PET contrast.

Self-preserving personal care products

OBJECTIVE

As questions on the safety of some popular preservatives are on the rise, there is a growing interest in developing 'self-preserving' personal care products. Use of multifunctional ingredients/actives with antimicrobial properties has been explored as replacements for conventional preservatives. This study explores the use of combinations of multifunctional actives (MFA) and other cosmetic ingredients in various personal care formulations, to deliver microbiologically safe self-preserving products. Products studied in this study include face wash, gel-based leave-on skin care product and face mask.

METHODS

Minimum inhibitory concentration (MIC) of several cosmetic ingredients was determined to identify multifunctional actives with antimicrobial activity. Personal care formulations made with multifunctional actives and other cosmetic ingredients were studied for preservative efficacy by challenging the product with six multiple cycles of microbial challenge.

RESULTS

Formulations with combinations of multifunctional actives with antioxidant (AO) and chelators (CHL) were found to work synergistically and were highly efficacious in controlling multiple microbial challenges as observed in the preservative efficacy test (PET) studies. The effective combinations were able to withstand up to six multiple microbial challenges without product degradation. The preservative efficacy profile was similar to control formula containing preservatives.

CONCLUSION

Self-preserving personal care/cosmetic products can be developed which are as efficacious as preserved products by a prudent selection of multifunctional actives, antioxidants and chelators as a part of the formulation.

Prophylactic and therapeutic vaccination with carrier-bound Bet v 1 peptides lacking allergen-specific T cell epitopes reduces Bet v 1-specific T cell responses via blocking antibodies in a murine model for birch pollen allergy

Background

Vaccines consisting of allergen-derived peptides lacking IgE reactivity and allergen-specific T cell epitopes bound to allergen-unrelated carrier molecules have been suggested as candidates for allergen-specific immunotherapy.

Objective

To study whether prophylactic and therapeutic vaccination with carrier-bound peptides from the major birch pollen allergen Bet v 1 lacking allergen-specific T cell epitopes has influence on Bet v 1-specific T cell responses.

Methods

Three Bet v 1-derived peptides, devoid of Bet v 1-specific T cell epitopes, were coupled to KLH and adsorbed to aluminium hydroxide to obtain a Bet v 1-specific allergy vaccine. Groups of BALB/c mice were immunized with the peptide vaccine before or after sensitization to Bet v 1. Bet v 1- and peptide-specific antibody responses were analysed by ELISA. T cell and cytokine responses to Bet v 1, KLH, and the peptides were studied in proliferation assays. The effects of peptide-specific and allergen-specific antibodies on T cell responses and allergic lung inflammation were studied using specific antibodies.

Results

Prophylactic and therapeutic vaccination with carrier-bound Bet v 1 peptides induced a Bet v 1-specific IgG antibody response without priming/boosting of Bet v 1-specific T cells. Prophylactic and therapeutic vaccination of mice with the peptide vaccine induced Bet v 1-specific antibodies which suppressed Bet v 1-specific T cell responses and allergic lung inflammation.

Conclusion and Clinical Relevance

Vaccination with carrier-bound allergen-derived peptides lacking allergen-specific T cell epitopes induces allergen-specific IgG antibodies which suppress allergen-specific T cell responses and allergic lung inflammation.

Incidence of diabetes mellitus in a population-based cohort of persons with chronic hepatitis B virus infection

To investigate the effect of hepatitis B virus (HBV) infection on the development of diabetes mellitus (DM), we compared DM incidence and characteristics of Alaska Native persons with and without HBV infection. From 1990 to 2010, there were 52 incident DM cases among 1309 persons with infection vs 4557 DM cases among 85 698 persons without infection (log-rank test, P = 0.20). Compared to infected persons without DM, those with DM were significantly older (57.0 vs 47.4 years, P < 0.001) and had higher body mass index (34.5 vs 28.4 kg/m(2) , P < 0.001). Genotype, immune active disease and the presence of cirrhosis were not associated with DM. In this population-based cohort with over 20 years of follow-up, there was no effect of HBV infection on DM development.

Necrotising otitis externa: an unusual cause of cranial nerve palsy in a diabetic haemodialysis patient

We present an unusual case of necrotising otitis externa (NOE) causing a lower motor neurone facial nerve palsy in a patient with diabetes mellitus and receiving maintenance haemodialysis for end-stage renal disease (ESRD). Pseudomonas aeruginosa is the most common pathogen isolated in NOE, although our case involved the non-typical pathogens Aspergillus flavus and Proteus mirabilis. We discuss the need for diagnostic rigour and the importance of considering atypical infective pathology in patients with ESRD or diabetes mellitus. We review NOE with reference to causative agents, imaging strategies, prognostic indicators and treatment.

Mydriasis in association with MMIHS in a female infant: evidence for involvement of the neuronal nicotinic acetylcholine receptor

We report a case of megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS), occurring in association with mydriasis, in a female infant born to consanguineous Asian parents. This association has not previously been reported and is of interest because mydriasis has been found in a murine MMIHS model produced by knockout of the genes coding for the alpha3 subunit or the beta2 and beta4 subunits of the neuronal nicotinic acetylcholine receptor. This may provide an important clue to the genetic basis of MMIHS in humans.

BK virus associated renal cell carcinoma: case presentation with optimized PCR and other diagnostic tests

Polyomaviruses, including BK and JC viruses, have been associated with graft failure, but have not commonly been associated with malignancy. We present a case of renal cell carcinoma arising in an allograft kidney, in which the tumor and metastasis contain viral DNA. Tumor and biopsy specimens from this patient were examined with hematoxylin & eosin, immunohistochemistry (IHC) and in situ hybridization (ISH). The results were confirmed by real-time polymerase chain reaction (PCR) analysis with BKV primers. Other viruses including herpes simplex 1-2, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and varicella zoster were not detected. The presence of BKV DNA in a renal cell carcinoma, including a metastatic focus, adds to the evidence that this virus may play a role in cancers of the kidney and urinary tract.

What is new with antibiotic-resistant gonorrhoea in Newcastle, England?

Neisseria gonorrhoeae isolates that were resistant to ciprofloxacin and/or penicillin were analysed to investigate the escalating problem of antibiotic-resistant gonorrhoea in the north east of England. Opa-typing (outer membrane opacity protein) was carried out on isolates resistant to ciprofloxacin and of nutrient nonrequiring (NR) auxotype. In the year 2000 there were 265 cases of gonorrhoea, of which 44 (16.6%) were resistant to penicillin and 12 (4.5%) were resistant or had reduced sensitivity to ciprofloxacin (with only four of these acquired outside the UK). Three (7.5%) of the non-beta-lactamase penicillin-resistant isolates were imported from abroad. By Opa-typing of ciprofloxacin-resistant strains, one pair of the isolates was similar, two were unique and one was similar to the Oldham/Rochdale outbreak strain described early in 2000. This marked increase in the prevalence of indigenous ciprofloxacin resistance requires continued surveillance and may soon necessitate an alteration in our first line treatment.

Prophylactic indomethacin: factors determining permanent ductus arteriosus closure

BACKGROUND

Permanent closure of the ductus arteriosus (DA) requires both effective muscular constriction to block luminal blood flow and anatomic remodeling to prevent later reopening.

OBJECTIVE

We examined the role of prophylactic indomethacin in producing permanent DA closure and the mechanism by which this occurs.

METHODS

We studied 2 separate approaches to managing a patent DA in 257 preterm infants (gestation 24 to 27 weeks): (1) prophylactic indomethacin (all infants treated during the first 15 hours after birth) or (2) symptomatic treatment (infants in this group received indomethacin only if clinical symptoms appeared; infants whose ductus closed spontaneously and never received indomethacin were included in this group). Echocardiography was performed 24 to 36 hours after the last dose of indomethacin was administered or by age 5 days if spontaneous closure occurred. Infants were monitored for the development of ductus reopening.

RESULTS

The prophylactic treatment group had a greater degree of initial ductus constriction, a higher rate of permanent anatomic closure, and a decreased need for surgical ligation than did the symptomatic treatment group. The degree of initial ductus constriction was the most important factor determining the rate of ductus reopening. Post-treatment echocardiography proved to be the best test for predicting eventual reopening.

CONCLUSION

Prophylactic indomethacin improved the rate of permanent ductus closure by increasing the degree of initial constriction. Prophylactic indomethacin did not affect the remodeling process, nor did it alter the inverse relationship between infant maturity and subsequent reopening. Even when managed with prophylactic indomethacin, the rate of ductus reopening remained unacceptably high in the most immature infants.

Incidence and outcome of a 10-fold indomethacin overdose in premature infants

We reviewed the incidence and morbidity of a 10-fold medication error among all premature infants treated with indomethacin. We detected 4 incidents among 1059 indomethacin doses given to infants weighing less than 1000 g. None of the infants had intracranial hemorrhage, necrotizing enterocolitis, or significant deterioration of renal function.

Antiovarian antibodies and their effect on the outcome of assisted reproduction

PURPOSE

To compare the presence in levels of antiovarian antibodies (AOAb) in the pre- and postovulatory stage from serum of infertile patients undergoing intrauterine insemination (IUI) or in vitro fertilization (IVF) with outcome of the procedures.

RESULTS

Serum from 36 women undergoing IUI, 36 women undergoing IVF and 25 fertile, healthy controls were assayed for the presence of AOAb by a commercially available ELISA kit. AOAb was positive in 59.7% of infertile women, while none of the fertile controls were positive for AOAb. The levels of these antibodies increased as the patient age and the number of treatment attempts increased. Though the presence of AOAb did not affect oocyte recovery rate, it resulted in decreased fertilization rate, cleavage rate, and pregnancy rate in infertile women.

CONCLUSIONS

Our studies suggest that AOAb may be a cause of infertility and presence of these antibodies could have adverse effects on the outcome of assisted reproductive techniques.

Central nervous system manifestations of a valproic acid overdose responsive to naloxone

We report the case of a 22-year-old man who presented with a depressed level of consciousness after ingesting valproic acid. He responded to IV naloxone; over a nine-hour period, his serum valproic acid level decreased from 180.4 to 59.2 micrograms/ml with multiple-dose charcoal therapy. We recommend the use of both agents in the treatment of valproic acid overdose.

Illness associated with child day care: a study of incidence and cost

We studied 843 children under 36 months of age enrolled in a prepaid health plan from September 1985 through March 1986, to identify characteristics of day care which might be risk factors for infection and to describe the resulting economic costs. Children cared for in their own home had a mean of 2.03 infections diagnosed during the study period. Adjusted rates of excess infection (95 per cent CI) for children cared for in other settings were: -.09 (-.73, .54) in relatives' homes; .10 (-.51, .71) in day care homes; .79 (.13, 1.45) in day care centers; .60 (-.24, 1.46) in mother's day out programs; and .66 (-.01, 1.34) in multiple settings. Children in day care centers were 4.5 times more likely to be hospitalized than those in other settings (95 per cent CI = 1.55, 13.00), primarily due to an increased rate of tympanostomy tube placement (relative risk 3.79, 95 per cent CI = 1.04, 13.36). The strongest predictor of illness risk was the number of other children in the room. The mean monthly cost of medical care was $32.94 for children in the highest risk settings compared with $19.78 for those in other settings. Illness in a child in our study accounted for 40 per cent of parental absenteeism from work; the mean number of days lost per month was 0.52 for parents of children in day care centers compared with 0.37 for those of children in other forms of full time care outside the home.

Course and resolution of the coagulopathy in nephrotic children

Blood coagulation function was serially studied in 84 children with nephrotic syndrome. Fifty-eight had minimal change disease, six had focal glomerulosclerosis and 20 had other forms of renal disease associated with the nephrotic syndrome. Qualitatively similar abnormalities in fibrinogen metabolism were present in all groups with clinically overt nephrotic syndrome; plasma fibrinogen concentration and high molecular weight fibrin(ogen) complexes (HMWFC) were grossly elevated (P less than 0.001 in most groups). With disease remission fibrinogen and HMWFC concentrations decreased to the normal range, usually with concomitant transient increase in plasma fibrinolytic activity (P less than 0.02). Alterations in concentrations of other proteins involved in coagulation and fibrinolysis differed depending on the underlying cause for the nephrotic syndrome. Antithrombin III concentration was normal except in the focal glomerulosclerosis group. The results demonstrate that a coagulopathy characterized by pathological degree of thrombin action on fibrinogen complicates the nephrotic state and may be initiated by different mechanisms. It is suggested that this coagulopathy, which remits with clinical improvement, is consequent upon local intrarenal activation of the blood coagulation system.

The changing face of peptic ulcer in the elderly

The elderly patient presents a challenge to the physician both in recognition of peptic ulcer disease and in long term management. Only with close observation and an awareness of the higher complication rate can a successful therapeutic approach be developed.

Maros-Schulek Technique for Measurement of Carbon Dioxide Production in Fish and Respiratory Quotient in Tilapia mossambica

The technique used by Maros et al. (Anal. Chim. Acta 25: 390–399, 1961) for accurate measurements of total carbon dioxide in small samples has been modified for large samples of water, enabling measurement of carbon dioxide production by small aquatic animals. Data obtained from Tilapia mossambica by using the present technique are discussed. The method is considered to be adequate for obtaining reliable estimates of carbon dioxide production in fish.