Fraction Size, Total Dose and Respiratory Control Impact Local Control in Adrenal SBRT

PURPOSE/OBJECTIVE(S)

Stereotactic body radiotherapy (SBRT) is an effective treatment for oligometastatic disease in multiple sites, however, the optimal radiation dose for long term local control of adrenal metastases has not yet been determined. The aim of this study is to evaluate outcomes of adrenal SBRT and to evaluate factors that correlate with local control MATERIALS/METHODS: After IRB approval, a retrospective data review of patients treated with SBRT on adrenal metastases was conducted, at a medical center in Israel between 2015 and 2021. Biologic Equivalent Dose (BED) were calculated using an alpha beta ration of 10. Kaplan Meier and Cox regression were calculated to describe the hazard ratio for local control and survival using statistical software.

RESULTS

Fifty-eight cases of adrenal SBRT were identified. The average age was 67 years (ranging 42-92). Forty-three percent of primary tumor was non-small cell lung cancer. The lesions were equally distributed between the right and left adrenal gland. Six patients had bilateral radiation treatment. Fifty-eight percent of the cases were in the setting of oligometastatic disease (less than 5 lesions) with the rest having progression in the adrenal. PET-CT scans were available for follow up in 55% of patients and CT in the rest. The average GTV volume was 42 cm2 respiratory control through 4D and breath hold was performed in 86% of cases. The median follow up time, for local control, was 10 months with a range of 1-54 mos. Univariate analysis local control, during the last follow up, was seen in 74% of cases. Total dosage was equal to or above 72 Gy and dosage per fraction was equal to or above 8 Gy. The use of respiratory motion was found significant for local control. Only a fraction size equal to or above 8 Gy and a total dosage equal to and above 72 Gy were found significant for local failure (HR = 0.26, p = 0.024 and HR = 0.28, p = 0.019). With multivariable analysis the dosage per fraction ≥8 Gy continued to be significant after adjusting for total dose, histology, side, and motion management. Two patients had clinical signs of adrenal insufficiency and both received bilateral adrenal radiation. Bowel toxicity was low: 1 patient had >G3 toxicity.

CONCLUSION

In the largest single institution series reported to date, we found unilateral adrenal SBRT to be safe, however, bilateral treatment harbors a risk of adrenal insufficiency. Dose per fraction ≥8 Gy was the most powerful predictor of local control, and a total dose ≥72gy and motion management were also significant. In conclusion, we propose a treatment regimen with a fraction size of at least 8 Gy and a total dosage of at least 72 Gy for evaluation, in a prospective clinical trial.

Colonic Hamartomatous Ganglioneuromatosis in a 4 Mo Old Puppy

A 4 mo old male goldendoodle puppy was evaluated for chronic hematochezia with a history of recurrent rectal prolapse and tenesmus. A colo-colonic intussusception was diagnosed via abdominal imaging. Surgery was elected to reduce the intussusception, wherein a colonic mass was discovered. Colonic resection and anastomosis was performed, and the tissue were submitted for histopathological examination. The puppy was diagnosed with colonic hamartomatous ganglioneuromatosis based on the presence of markedly hyperplastic submucosal and myenteric plexi with infiltration and expansion of the mucosa and submucosa by Schwann cells and neuronal cell bodies. Ganglioneuromatosis is a rarely reported entity in the veterinary literature, and limited clinical follow up data is available for described cases. In humans, ganglioneuromatosis is associated with a PTEN genetic mutation, which confers increased susceptibility to the development of neoplasia of endocrine organs. Approximately 1 yr after the operation, this puppy appeared clinically normal with no abnormalities on repeated imaging. This case report describes the clinical presentation, surgical treatment, and histologic features of colonic hamartomatous ganglioneuromatosis with 1 yr postoperative clinical follow up data in a dog. Although uncommon, ganglioneuromatosis should be considered as a differential diagnosis list as a cause of gastrointestinal masses in puppies and young dogs.

Spatiotemporal modeling of laser tissue soldering using photothermal nanocomposites

OBJECTIVE

Laser tissue soldering using photothermal solders is a technology that facilitates rapid sealing using heat-induced changes in the tissue and the solder material. The solder material is made of gold nanorods embedded in a protein matrix patch that can be placed over the tissue rupture site and heated with a laser. Although laser tissue soldering is an attractive approach for surgical repair, potential photothermal damage can limit the success of this approach. Development of predictive mathematical models of photothermal effects including cell death, can lead to more efficient approaches in laser-based tissue repair.

METHODS

We describe an experimental and modeling investigation into photothermal solder patches for sealing porcine and mouse cadaver intestine sections using near-infrared laser irradiation. Spatiotemporal changes in temperature were determined at the surface as well as various depths below the patch. A mathematical model, based on the finite element method, predicts the spatiotemporal temperature distribution in the patch and surrounding tissue, as well as concomitant cell death in the tissue is described.

RESULTS

For both the porcine and mouse intestine systems, the model predicts temperatures that are quantitatively similar to the experimental measurements with the model predictions of temperature increase often being within a just a few degrees of experimental measurements.

CONCLUSION

This mathematical model can be employed to identify optimal conditions for minimizing healthy cell death while still achieving a strong seal of the ruptured tissue using laser soldering. Lasers Surg. Med. 50:143-152, 2018. © 2017 Wiley Periodicals, Inc.

Three-dimensional piezoelectric fibrous scaffolds selectively promote mesenchymal stem cell differentiation

The discovery of electric fields in biological tissues has led to efforts in developing technologies utilizing electrical stimulation for therapeutic applications. Native tissues, such as cartilage and bone, exhibit piezoelectric behavior, wherein electrical activity can be generated due to mechanical deformation. Yet, the use of piezoelectric materials have largely been unexplored as a potential strategy in tissue engineering, wherein a piezoelectric biomaterial acts as a scaffold to promote cell behavior and the formation of large tissues. Here we show, for the first time, that piezoelectric materials can be fabricated into flexible, three-dimensional fibrous scaffolds and can be used to stimulate human mesenchymal stem cell differentiation and corresponding extracellular matrix/tissue formation in physiological loading conditions. Piezoelectric scaffolds that exhibit low voltage output, or streaming potential, promoted chondrogenic differentiation and piezoelectric scaffolds with a high voltage output promoted osteogenic differentiation. Electromechanical stimulus promoted greater differentiation than mechanical loading alone. Results demonstrate the additive effect of electromechanical stimulus on stem cell differentiation, which is an important design consideration for tissue engineering scaffolds. Piezoelectric, smart materials are attractive as scaffolds for regenerative medicine strategies due to their inherent electrical properties without the need for external power sources for electrical stimulation.

Cluster randomized trial to evaluate the impact of team training on surgical outcomes

Background

The application of safety principles from the aviation industry to the operating room has offered hope in reducing surgical complications. This study aimed to assess the impact on major surgical complications of adding an aviation-based team training programme after checklist implementation.

Methods

A prospective parallel-group cluster trial was undertaken between September 2011 and March 2013. Operating room teams from 31 hospitals were assigned randomly to participate in a team training programme focused on major concepts of crew resource management and checklist utilization. The primary outcome measure was the occurrence of any major adverse event, including death, during the hospital stay within the first 30 days after surgery. Using a difference-in-difference approach, the ratio of the odds ratios (ROR) was estimated to compare changes in surgical outcomes between intervention and control hospitals.

Results

Some 22 779 patients were enrolled, including 5934 before and 16 845 after team training implementation. The risk of major adverse events fell from 8·8 to 5·5 per cent in 16 intervention hospitals (adjusted odds ratio 0·57, 95 per cent c.i. 0·48 to 0·68; P < 0·001) and from 7·9 to 5·4 per cent in 15 control hospitals (odds ratio 0·64, 0·50 to 0·81; P < 0·001), resulting in the absence of difference between arms (ROR 0·90, 95 per cent c.i. 0·67 to 1·21; P = 0·474). Outcome trends revealed significant improvements among ten institutions, equally distributed across intervention and control hospitals.

Conclusion

Surgical outcomes improved substantially, with no difference between trial arms. Successful implementation of an aviation-based team training programme appears to require modification and adaptation of its principles in the context of the the surgical milieu. Registration number: NCT01384474 (http://www.clinicaltrials.gov).

Value of laboratory studies in assessment of dehydration in children

Background: Due to the lack of a reliable way of clinically measuring dehydration, laboratory tests are usually used to improve the accuracy of clinical assessment of dehydration in children. The purpose of this study was to compare the relationship between clinical and laboratory parameters in the assessment of dehydration and to evaluate the improvement of those parameters over time.

Methods: We conducted a retrospective study to assess the relationship between clinical assessment of dehydration and laboratory findings.

Results: Three hundred children were eligible for the study. Twenty-six per cent of those with mild dehydration had serum urea concentrations greater than 14.3 mmol/L, compared with 38% and 5% of those with moderate or no dehydration, respectively. Urea concentration showed a good specificity, 95%. Creatinine concentrations and mean pH were similar whether or not dehydration was present. Bicarbonate and base excess concentrations decreased with the increasing severity of dehydration and were significantly greater in subjects with moderate dehydration than in those without. The sensitivity (71%) and specificity (74%) of both tests were rather poor. All groups had an abnormal anion gap, which was significantly greater in those with mild or moderate dehydration.

Conclusion: This study confirms that there is a discrepancy between clinical assessment and laboratory parameters of dehydration. Urea showed good specificity, and anion gap was the most sensitive laboratory parameter for assessment of dehydration. These findings need further validation.

Recent Developments In Fluoro-containing Polyamideimides

The synthesis, characterization and development of a new generation of fluoro-containing polyamideimide (PAI) polymers are described in this paper. The polymers are generally prepared by forming the polycondensation product of an aromatic diamine, a trifunctional aromatic anhydride acid chloride and an aromatic dianhydride containing trifluoromethyl moieties. These new materials possess high glass transition temperatures, useful mechanical properties and outstanding thermoplastic flow behavior which render them readily melt processable into fibers, films, sheets and other molded articles. The as-precipitated fluoro-containing PAI materials are soluble in many organic solvents and are thus amenable to solution casting techniques. They also show excellent resistance towards thermooxidative degradation at temperatures to 450°F and have low moisture uptake. In addition, compatible blends with polybenzimidazole (PBI) resin have yield synergistic effects on the mechanical properties of the resulting polymer.

Sleep Patterns of Infants and Young Children in Israel

The sleep habits of 661 Israeli children between the ages of 4 months and 4 years were described by their mothers. Twenty-eight per cent reported that their children woke up at least once a week. In the group of regular wakers, the mean number of interrupted nights per week was 4.7, and the mean number of awakenings per night was 2.0. Significant age-related changes in sleep patterns were indicated. The results of this study suggest that sleep and settling patterns in different sociocultural groups are quite similar. These data indicate the existence of an inherent pattern in the maturation of sleep behaviour in the developing child.

Sleep, Sleep Disorders, and Mild Traumatic Brain Injury. What We Know and What We Need to Know: Findings from a National Working Group

Disturbed sleep is one of the most common complaints following traumatic brain injury (TBI) and worsens morbidity and long-term sequelae. Further, sleep and TBI share neurophysiologic underpinnings with direct relevance to recovery from TBI. As such, disturbed sleep and clinical sleep disorders represent modifiable treatment targets to improve outcomes in TBI. This paper presents key findings from a national working group on sleep and TBI, with a specific focus on the testing and development of sleep-related therapeutic interventions for mild TBI (mTBI). First, mTBI and sleep physiology are briefly reviewed. Next, essential empirical and clinical questions and knowledge gaps are addressed. Finally, actionable recommendations are offered to guide active and efficient collaboration between academic, industry, and governmental stakeholders.

Structural changes in PVDF fibers due to electrospinning and its effect on biological function

Polyvinylidine fluoride (PVDF) is being investigated as a potential scaffold for bone tissue engineering because of its proven biocompatibility and piezoelectric property, wherein it can generate electrical activity when mechanically deformed. In this study, PVDF scaffolds were prepared by electrospinning using different voltages (12-30 kV), evaluated for the presence of the piezoelectric β-crystal phase and its effect on biological function. Electrospun PVDF was compared with unprocessed/raw PVDF, films and melt-spun fibers for the presence of the piezoelectric β-phase using differential scanning calorimetry, Fourier transform infrared spectroscopy and x-ray diffraction. The osteogenic differentiation of human mesenchymal stem cells (MSCs) was evaluated on scaffolds electrospun at 12 and 25 kV (PVDF-12 kV and PVDF-25 kV, respectively) and compared to tissue culture polystyrene (TCP). Electrospinning PVDF resulted in the formation of the piezoelectric β-phase with the highest β-phase fraction of 72% for electrospun PVDF at 25 kV. MSCs cultured on both the scaffolds were well attached as indicated by a spread morphology. Cells on PVDF-25 kV scaffolds had the greatest alkaline phosphatase activity and early mineralization by day 10 as compared to TCP and PVDF-12 kV. The results demonstrate the potential for the use of PVDF scaffolds for bone tissue engineering applications.

Polyimide Copolymers Containing Various Levels Of The 6F Moiety For High Temperature And Microelectronic Applications

Trifluoromethyl group-containing polyimides not only show extraordinary electrical properties, but they also exhibit excellent long-term thermo-oxidative stability. Among the most thermomechanically stable structural polyimides are those from 6F dianhydride (6FDA) and 6F diamines. The effects of substituting non-fluorine containing monomers such as BTDA, mPDA and 4,4′-DADPS for the hexafluoroisopropylidene monomers on the dielectric, thermo-oxidative, thermal and mechanical properties of the copolymers were studied.

Characterization and in vitro cytocompatibility of piezoelectric electrospun scaffolds

Previous studies have shown that electrical charges influence cell behavior (e.g. enhancement of nerve regeneration, cell adhesion, cell morphology). Thus, piezoelectric scaffolds might be useful for various tissue engineering applications. Fibrous scaffolds were successfully fabricated from permanent piezoelectric poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) by the electrospinning technique. Scanning electron microscopy and capillary flow analyses verified that the fiber mats had an average fiber diameter of 970 +/- 480 nm and a mean pore diameter of 1.7 microm, respectively. Thermally stimulated depolarization current spectroscopy measurements confirmed the piezoelectric property of the PVDF-TrFE fibrous scaffolds by the generation of a spontaneous current with the increase in temperature in the absence of an electric field, which was not detected in the unprocessed PVDF-TrFE powder. Differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Fourier transform infrared spectroscopy results showed that the electrospinning process increased the crystallinity and presence of the polar, beta-phase crystal compared with the unprocessed powder. Confocal fluorescence microscopy and a cell proliferation assay demonstrated spreading and increased cell numbers (human skin fibroblasts) over time on PVDF-TrFE scaffolds, which was comparable with tissue culture polystyrene. The relative quantity of gene expression for focal adhesion proteins (measured by real-time RT-PCR) increased in the following order: paxillin < vinculin < focal adhesion kinase < talin. However, no differences could be seen among the TCPS surface and the fibrous scaffolds. Future studies will focus on possible applications of these cytocompatible PVDF-TrFE scaffolds in the field of regenerative medicine.

A comparison of degradable synthetic polymer fibers for anterior cruciate ligament reconstruction

We compared mechanical properties, degradation rates, and cellular compatibilities of two synthetic polymer fibers potentially useful as ACL reconstruction scaffolds: poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate)(12,10), p(DTD DD) and poly(L-lactic acid), PLLA. The yield stress of ethylene oxide (ETO) sterilized wet fibers was 150 +/- 22 MPa and 87 +/- 12 MPa for p(DTD DD) and PLLA, respectively, with moduli of 1.7 +/- 0.1 MPa and 4.4 +/- 0.43 MPa. Strength and molecular weight retention were determined after incubation under physiological conditions at varying times. After 64 weeks strength decreased to 20 and 37% of the initial sterile fiber values and MW decreased to 41% and 36% of the initial values for p(DTD DD) and PLLA, respectively. ETO sterilization had no significant effect on mechanical properties. Differences in mechanical behavior may be due to the semicrystalline nature of PLLA and the small degree of crystallinity induced by mesogenic ordering in p(DTD DD) suggested by DSC analysis. Fibroblast growth was similar on 50-fiber scaffolds of both polymers through 16 days in vitro. These data suggest that p(DTD DD) fibers, with higher strength, lower stiffness, favorable degradation rate and cellular compatibility, may be a superior alternative to PLLA fibers for development of ACL reconstruction scaffolds.

The effect of processing history on physical behavior and cellular response for tyrosine-derived polyarylates

Polyarylates have shown promise as fully degradable polymers for drug delivery as well as for structural implant applications due to their range of physicomechanical properties. Processing history, however, could have a significant impact on their overall performance in biologically relevant environments. More specifically, structural changes at the molecular level can occur that will affect a polymer's physical properties and subsequent, cell attachment and growth. The present study was aimed at comparing cell growth on tyrosine-derived polyarylates with that of polylactic acid (PLLA) in their original state and after processing (i.e. undrawn and drawn forms). Two polyarylates having distinct molecular structures were chosen. Strictly, amorphous poly(DTE adipate), denoted as poly(DT 2,4), and poly(DTD) dodecandioate, denoted as poly(DT 12,10), having a more complex, non-crystalline organization, were compared with semi-crystalline PLLA. The degree of shrinkage, thermal characterization, air-water contact angle and surface morphology were determined for each polymer in its undrawn and drawn states. Poly(DT 2,4) and PLLA after processing resulted in greater shrinkage and a slight decrease in hydrophilicity whereas poly(DT 12,10) had minimal shrinkage and became slightly more hydrophilic in its drawn state. Surface morphology or roughness was also altered by processing. In turn, the rate of cell growth and overall cell numbers were reduced significantly on drawn forms of poly(DT 2,4) and PLLA, whereas more favorable growth rates were supported on drawn poly(DT 12,10). These findings indicate that processing effects in amorphous as well as oriented polymeric structures can significantly alter their biological performance.

Design of a Filamentous Polymeric Scaffold forin VivoGuided Angiogenesis

Angiogenesis is mandatory for reperfusion of viable tissues, and lack of vascularization may cause ischemia. The increasing disparity between the demand and availability of adequate substitutes for small-diameter human blood vessels has prompted an intensive search for artificial materials or biological allograft tissues, both of which usually fail in the long term. The objective of this study was to pioneer a novel model for in vivo guided angiogenesis based on a specific design process of a filamentous polymeric scaffold with endothelial cells in a 3-dimensional culture system. To our knowledge, this is the first report of an in vivo guided angiogenesis approach based on a 2-step model, composed of endothelial cells and a filamentous polymeric scaffold framework. Endothelial cells that had been cultured on a specifically designed filamentous polymeric scaffold within a regulated dynamic tissue culture system were shown in vivo to induce guided angiogenesis. Cells seeded on a biodegradable polymeric scaffold were implanted into mice. On day 28 after implantation, analysis revealed a guided angiogenic process along the path of the implanted polymeric scaffold as well as initial evidence for early maturation of engineered vessels, allowing red blood cells to flow through the forming lumina of new vessels as the polymer degraded. The authors conclude that in vivo guided angiogenesis can be achieved by combining endothelial cells with biodegradable filamentous polymeric scaffolds and that this model can lay the cornerstone for vascular engineering and future development of clinically available protocols aimed to treat life-threatening cardiovascular conditions.