Evaluation of Safety Outcomes of Undiluted Levetiracetam Intravenous Push Compared to Intravenous Piggyback

Background: Breakthrough seizures and status epilepticus require urgent management. Administration of intravenous push (IVP) levetiracetam has been demonstrated to be safe as compared to intravenous piggyback (IVPB). This transition can potentially offer faster time to administration and reduced drug and material cost. The objective of this study was to observe safety of administration in patients receiving levetiracetam via IVP compared to IVPB in acute care settings. Methods: This is a multi-center, observational, retrospective cohort study of 1214 adult patients who received levetiracetam pre- and post-implementation of IVP over a 6 month timespan. Primary outcome was time from order verification to administration of urgent first-time doses. Secondary outcomes included time to administration of loading doses and cost. Safety outcome was infusion site related reactions. Results: Time from order verification to administration of urgent first-time doses pre- and post-implementation of IVP administration was reduced from 61 minutes to 47 minutes (P=0.0002). Infusion site related reactions were observed in 6 out of 5432 doses in the IVPB arm and in 5 out of 4700 doses in the IVP arm (P=1). Total estimated cost was $76,171.96 for the 5449 IVPB total doses and $11,484.33 for the 4721 IVP total doses. Conclusions: Transition from IVPB to IVP administration reduced time from order verification to administration of urgent first-time doses with both administrations having similar incidence of infusion site related reactions. Cost savings and improved workflow were observed. Levetiracetam administered via IVP may be considered as a safe alternative method of administration in the acute care setting.

Hopanoid lipids promote soybean-Bradyrhizobium symbiosis

The symbioses between leguminous plants and nitrogen-fixing bacteria known as rhizobia are well known for promoting plant growth and sustainably increasing soil nitrogen. Recent evidence indicates that hopanoids, a family of steroid-like lipids, promote Bradyrhizobium symbioses with tropical legumes. To characterize hopanoids in Bradyrhizobium symbiosis with soybean, we validated a recently published cumate-inducible hopanoid mutant of Bradyrhizobium diazoefficiens USDA110, Pcu-shc::∆shc. GC-MS analysis showed that this strain does not produce hopanoids without cumate induction, and under this condition, is impaired in growth in rich medium and under osmotic, temperature, and pH stress. In planta, Pcu-shc::∆shc is an inefficient soybean symbiont with significantly lower rates of nitrogen fixation and low survival within the host tissue. RNA-seq revealed that hopanoid loss reduces the expression of flagellar motility and chemotaxis-related genes, further confirmed by swim plate assays, and enhances the expression of genes related to nitrogen metabolism and protein secretion. These results suggest that hopanoids provide a significant fitness advantage to B. diazoefficiens in legume hosts and provide a foundation for future mechanistic studies of hopanoid function in protein secretion and motility.

A major problem for global sustainability is feeding our exponentially growing human population while available arable land decreases. Harnessing the power of plant-beneficial microbes is a potential solution, including increasing our reliance on the symbioses of leguminous plants and nitrogen-fixing rhizobia. This study examines the role of hopanoid lipids in the symbiosis between Bradyrhizobium diazoefficiens USDA110, an important commercial inoculant strain, and its economically significant host soybean. Our research extends our knowledge of the functions of bacterial lipids in symbiosis to an agricultural context, which may one day help improve the practical applications of plant-beneficial microbes in agriculture.

Pencil Beam Scanning Proton Stereotactic Body Radiation Therapy (SBRT): A Robust Single Institution Experience

PURPOSE/OBJECTIVE(S)

To describe the feasibility of treating a complex and diverse group of patients using pencil beam scanning (PBS) proton stereotactic body radiation therapy (SBRT: 5 or fewer fractions, with a fraction size of at least 5 Gy).

MATERIALS/METHODS

Our center treats on average 105-120 PBS proton treatments daily, of which 9.5% of treatment courses are proton SBRT. Statistics of disease sites, treatment planning parameters (target volume, prescriptions, number of fields, SFO vs. MFO), and treatment efficiencies (scheduled time slots, actual treatment time) are presented for 305 consecutive SBRT patients receiving 1507 fractions in the past three years. Thermoplastic masks or Vacuum-lock bags are used to immobilize SBRT patients and index the patients' treatment position. Imaging guidance of orthogonal kV images and volumetric cone-beam CT is routinely used for patient setup.

RESULTS

SBRT patients are grouped based on the target locations: pelvis (31%), liver (17%), thoracic (13%), spine (8%), abdominal (8%), brain (7%), non-spine bone (7%), ocular (6%), and head and neck (2%). Only 112 patients (37%) were receiving their 1st RT course, whereas 113 (37%) had one prior in-field RT course, and 80 (26%) had multiple prior in-field RT courses. The median [IQR] target volume was 65.4 [29.3, 168] cc (range: 0.3-2475 cc). 72% of cases were planned with SFO and 28% with MFO. On average, 3.76 fields (range: 2 to 12) were planned for each treatment. 44% of the treatments were planned with three or fewer fields, and 10% received more than five fields, most of which involved repainting for moving targets. Over 97% of treatments were delivered in 5 fractions, with ∼3% delivered in 3 fractions. The median [IQR] prescription per treatment was 8 [7, 10] Gy (range: 5-18 Gy per treatment). 85% (84%) of the SBRT treatments were scheduled (delivered) in a 45-minute or shorter slot, and 6% (7%) of treatments were scheduled (delivered) in over a one-hour slot, most commonly for multiple isocenter treatments. 93% of treatments were delivered within 15 minutes of the planned treatment time or shorter. Deep-inspiration breath-hold (DIBH) was applied to 45% of liver SBRT cases, with the remaining 55% planned on 4D CT with (14%) or without (86%) abdominal compression. DIBH was applied in 13% of lung SBRT cases. The application of other motion mitigation approaches, such as volumetric repainting, was determined by the target motion amplitude and whether the patient could tolerate DIBH.

CONCLUSION

In the most diverse and largest proton SBRT experience delivered in the world over the past 3 years, over 300 patients were treated, demonstrating the feasibility and efficiency of delivering proton SBRT in a very busy center. The planning and treatment parameter statistics reported serve as a helpful reference for the proton community.

A Dosimetric Assessment of Sexual Organ Sparing Proton Radiotherapy in Female Pelvic Cancer Patients

PURPOSE/OBJECTIVE(S)

Optimizing treatment techniques for female patients undergoing curative treatment for pelvic cancers requires incorporating the goals of maximizing cure while maintaining quality of life. Optimizing treatment to maintain sexual quality of life has received little attention in female patients despite the presence of and toxicity risks to functional anatomic organs and their associated neurovasculature, including the bulboclitoris, vagina, and ovaries. Recent dosimetric data without employing sexual organ sparing suggest that mean VMAT dose to the bulboclitoris in low rectal cancer is around 3300 cGy, and in anal cancer, mean dose is around 2000 cGy to the external genitalia and 4500-5000 cGy to the bulboclitoris, all of which would be expected to result in clinically significant toxicity. Therefore, investigation of the avoidance of these important organs is needed and we hypothesize that proton techniques may achieve greater sparing than photon techniques.

MATERIALS/METHODS

In this study, we dosimetrically compare proton- vs. photon-based techniques in sparing functional sexual organs. The cohort consisted of four consecutive female pelvic cancer cases that had received 5000 cGy or greater. All cases were re-planned with VMAT and protons while optimizing dose to functional sexual organs and maintaining target coverage. Sexual organ structures assessed include the genitalia, vagina, ovaries, bulboclitoris and internal pudendal arteries. Given the small number of patients included in this demonstration study, statistical tests were not performed.

RESULTS

MRI was required to appropriately delineate soft tissue. In all cases, dosimetric sparing of sexual organs was improved with proton therapy without compromising target coverage. Mean doses were marginally decreased for structures within the PTV, while structures such as the bulboclitoris were spared substantially. Mean dose to the external genitalia was low with sparing using both VMAT (Median [IQR] (cGy): 852 [811, 1090]) and Proton techniques (Median [IQR] (cGy): 39.4 [11.9, 78.5]). Similarly, mean dose with sparing to the external genitalia was lower than would be expected without sparing, using both VMAT and Proton techniques (Median (IQR) Dmean (cGy) VMAT 3100 [2890, 3580] vs. Proton 1530 [1100, 2090]), with protons demonstrating greater sparing. In one case of a sacral chordoma, ovaries were substantially spared to below ablative thresholds (Dmean (cGy) VMAT 3598.8 and 3548.0 vs Proton 34.1 and 103.3).

CONCLUSION

Magnetic resonance imaging at simulation combined with proton radiotherapy for female sexual organ sparing may provide a technically feasible route to more equitable sexual outcomes for female patients. These results will guide future studies to optimize proton treatment techniques for female sexual organ sparing for future trials.

Hopanoid lipids promote soybean- Bradyrhizobium symbiosis

The symbioses between leguminous plants and nitrogen-fixing bacteria known as rhizobia are well known for promoting plant growth and sustainably increasing soil nitrogen. Recent evidence indicates that hopanoids, a family of steroid-like lipids, promote Bradyrhizobium symbioses with tropical legumes. To characterize hopanoids in Bradyrhizobium symbiosis with soybean, the most economically significant Bradyrhizobium host, we validated a recently published cumate-inducible hopanoid mutant of Bradyrhizobium diazoefficiens USDA110, Pcu- shc ::Δ shc . GC-MS analysis showed that this strain does not produce hopanoids without cumate induction, and under this condition, is impaired in growth in rich medium and under osmotic, temperature, and pH stress. In planta , Pcu- shc ::Δ shc is an inefficient soybean symbiont with significantly lower rates of nitrogen fixation and low survival within host tissue. RNA-seq revealed that hopanoid loss reduces expression of flagellar motility and chemotaxis-related genes, further confirmed by swim plate assays, and enhances expression of genes related to nitrogen metabolism and protein secretion. These results suggest that hopanoids provide a significant fitness advantage to B. diazoefficiens in legume hosts and provide a foundation for future mechanistic studies of hopanoid function in protein secretion and motility.

IMPORTANCE

A major problem for global sustainability is feeding our exponentially growing human population while available arable land is decreasing, especially in areas with the greatest population growth. Harnessing the power of plant-beneficial microbes has gained attention as a potential solution, including the increasing our reliance on the symbioses of leguminous plants and nitrogen-fixing rhizobia. This study examines the role of hopanoid lipids in the symbiosis between Bradyrhizobium diazoefficiens USDA110, an important commercial inoculant strain, and its economically important host soybean. Our research extends our knowledge of the functions of bacterial lipids in symbiosis to an agricultural context, which may one day help improve the practical applications of plant-beneficial microbes in agriculture.