Tibial osteochondroma with thick cartilage which mimicked a chondrosarcoma: A case report

We report a case of tibial osteochondroma in a 25-year-old female who presented with a palpable calf mass. This mass was associated with a thick cartilaginous cap on cross-sectional imaging, suggesting chondrosarcoma. A CT-guided biopsy was performed, and histology, however, was consistent with osteochondroma. Orthopedic oncology recommended surgical excision due to the potential high sampling error with chondroid lesions. The patient underwent surgical resection, resulting in a final diagnosis of osteochondroma. No post-surgical complications occurred, and a 12-month follow-up showed no evidence of local recurrence. This case highlights the atypical imaging feature of a thick cartilaginous cap in a benign etiology without malignant transformation.

Computational prediction of proximal sealing in endovascular abdominal aortic aneurysm repair with unfavorable necks

BACKGROUND AND OBJECTIVE

Endovascular aortic aneurysm repair (EVAR) has become the standard treatment for abdominal aortic aneurysms in most centers. However, proximal sealing complications leading to endoleaks and migrations sometimes occur, particularly in unfavorable aortic anatomies and are strongly dependent on biomechanical interactions between the aortic wall and the endograft. The objective of the present work is to develop and validate a computational patient-specific model that can accurately predict these complications.

METHODS

Based on pre-operative CT-scans, we developed finite element models of the aorta of 10 patients who underwent endovascular aortic aneurysm repair, 7 with standard morphologies and 3 with unfavorable anatomies. We simulated the deployment of stent grafts in each aorta by solving mechanical equilibrium with a virtual shell method. Eventually we compared the actual stent ring positions from post-operative computed-tomography-scans with the predicted simulated positions.

RESULTS

A successful deployment simulation could be performed for each patient. Relative radial, transverse and longitudinal deviations were 6.3 ± 4.4%, 2.5 ± 0.9 mm and 1.4 ± 1.1 mm, respectively.

CONCLUSIONS

The numerical model predicted accurately stent-graft positions in the aortic neck of 10 patients, even in complex anatomies. This shows the potential of computer simulation to anticipate possible proximal endoleak complications before EVAR interventions.

A Humeral Osteosarcoma Mimicking Osseous Leiomyosarcoma: A Case Report

Osteosarcoma stands as one of the primary mesenchymal bone neoplasms commonly encountered in clinical practice. This malignancy often presents with a wide range of distinctive imaging characteristics. Here, we present a unique case wherein a delayed diagnosis of high-grade osteosarcoma occurred due to the absence of an osteoid matrix in the initial imaging studies. A 61-year-old female, initially presented with a left humeral fracture. As the healing of the fractured bone was delayed and the possibility of a pathologic fracture was considered, a CT-guided biopsy was performed. Histological examination of the biopsy sample initially suggested an osseous leiomyosarcoma. The lack of osteoid matrix on radiographs including aggressive intra-medullary mass seen on MRI, combined with the patient's age, appeared consistent with a diagnosis of leiomyosarcoma of bone. As a result, the initial diagnosis was not called into question. Due to neurovascular involvement, this led to a forequarter amputation. However, upon microscopic examination of the amputation specimen, certain areas exhibited features indicative of malignant osteoid deposition, ultimately supporting a revised diagnosis of high-grade osteosarcoma. This case underscores the critical importance of considering the limitations of core biopsy samples, especially when dealing with suspected limb masses associated with pathological fractures. Radiographs and CT scans can prove invaluable in ruling out subtle adjacent osteoid, and ultimately a multidisciplinary approach to the diagnosis of osteosarcoma is imperative to ensure accurate identification.

Rhabdomyosarcoma: Current Therapy, Challenges, and Future Approaches to Treatment Strategies

Rhabdomyosarcoma is a rare cancer arising in skeletal muscle that typically impacts children and young adults. It is a worldwide challenge in child health as treatment outcomes for metastatic and recurrent disease still pose a major concern for both basic and clinical scientists. The treatment strategies for rhabdomyosarcoma include multi-agent chemotherapies after surgical resection with or without ionization radiotherapy. In this comprehensive review, we first provide a detailed clinical understanding of rhabdomyosarcoma including its classification and subtypes, diagnosis, and treatment strategies. Later, we focus on chemotherapy strategies for this childhood sarcoma and discuss the impact of three mechanisms that are involved in the chemotherapy response including apoptosis, macro-autophagy, and the unfolded protein response. Finally, we discuss in vivo mouse and zebrafish models and in vitro three-dimensional bioengineering models of rhabdomyosarcoma to screen future therapeutic approaches and promote muscle regeneration.

[Drugs: minors and harm reduction?]

The use of controlled substances (narcotics and psychotropic substances) poses increased risks for minors. However, minors are generally excluded from existing harm reduction services (e.g. drug consumption rooms, drug checking, exchange of consumption material). Based on public health considerations, the authors recommend the establishment of harm reduction services for minors.

Machine learning and reduced order modelling for the simulation of braided stent deployment

Endoluminal reconstruction using flow diverters represents a novel paradigm for the minimally invasive treatment of intracranial aneurysms. The configuration assumed by these very dense braided stents once deployed within the parent vessel is not easily predictable and medical volumetric images alone may be insufficient to plan the treatment satisfactorily. Therefore, here we propose a fast and accurate machine learning and reduced order modelling framework, based on finite element simulations, to assist practitioners in the planning and interventional stages. It consists of a first classification step to determine a priori whether a simulation will be successful (good conformity between stent and vessel) or not from a clinical perspective, followed by a regression step that provides an approximated solution of the deployed stent configuration. The latter is achieved using a non-intrusive reduced order modelling scheme that combines the proper orthogonal decomposition algorithm and Gaussian process regression. The workflow was validated on an idealized intracranial artery with a saccular aneurysm and the effect of six geometrical and surgical parameters on the outcome of stent deployment was studied. We trained six machine learning models on a dataset of varying size and obtained classifiers with up to 95% accuracy in predicting the deployment outcome. The support vector machine model outperformed the others when considering a small dataset of 50 training cases, with an accuracy of 93% and a specificity of 97%. On the other hand, real-time predictions of the stent deployed configuration were achieved with an average validation error between predicted and high-fidelity results never greater than the spatial resolution of 3D rotational angiography, the imaging technique with the best spatial resolution (0.15 mm). Such accurate predictions can be reached even with a small database of 47 simulations: by increasing the training simulations to 147, the average prediction error is reduced to 0.07 mm. These results are promising as they demonstrate the ability of these techniques to achieve simulations within a few milliseconds while retaining the mechanical realism and predictability of the stent deployed configuration.

Experience of memory: transfer of the motor feeling of fluency linked to our interaction with the environment

In the field of memory, it is now admitted that an experience of memory is not only the consequence of the activation of a precise content, but also results from an inference associated with the transfer of the manner in which the process was carried out (i.e., fluency) in addition to the transfer of the process itself. The aim of this work was to show that experience of memory is also associated with the fluency that is due to the transfer of a processing carried out in our past interactions with our environment, independently the fluency associated with the stimulus in progress. First, participants performed a perceptual discrimination task (geometric shapes: circle or square) that involves a fluent or a non-fluent gesture to respond. Motor fluency vs. non-fluency was implicitly associated with the colour of the geometric shapes. Second, participants had to perform a classical memory recognition task. During the recognition phase, items appeared either with the colour associated with motor fluency or with the colour associated with motor non-fluency. We used a Go-NoGo task to avoid having a confused factor (response space). Results show that items were better recognised with a colour associated with motor fluency than with a colour associated with non-motor fluency. These findings support the idea that an experience of memory is also associated with the transfer of the motor feeling of fluency linked to our past interactions with the environment.

Selection of M2+-independent RNA-cleaving DNAzymes with Sidechains Mimicking Arginine and Lysine

Sequence-specific cleavage of RNA by nucleic acid catalysts in the absence of a divalent metal cation (M 2+ ) has remained an important goal in biomimicry with potential therapeutic applications. Given the lack of functional group diversity in canonical nucleotides, modified nucleotides with amino acid-like side chains were used to enhance self-cleavage rates at a single embedded ribonucleoside site. Previous works relied on three functional groups: an amine, a guanidine and an imidazole ensconced on three different nucleosides. However, to date, few studies have systematically addressed the necessity of all three modifications, as the value of any single modified nucleoside is contextualized at the outset of selection. Herein, we report on the use of only two modified dNTPs, excluding an imidazole, i.e. 5-(3-guanidinoallyl)-2'-dUTP (dU ga TP) and 5-aminoallyl-2'-dCTP (dC aa TP), to select in-vitro self-cleaving DNAzymes that cleave in the absence of M 2+ in a pH-independent fashion. Cleavage shows biphasic kinetics with rate constants that are significantly higher than in unmodified DNAzymes and compare favorably to certain DNAzymes involving an imidazole. This work is the first report of a M2+-independent DNAzyme with two cationic modifications; as such it shows appreciable self-cleaving activity in the absence of an imidazole modification.

Pitolisant, a wake-promoting agent devoid of psychostimulant properties: Preclinical comparison with amphetamine, modafinil, and solriamfetol

Several therapeutic options are currently available to treat excessive daytime sleepiness (EDS) in patients suffering from narcolepsy or obstructive sleep apnea. However, there are no comparisons between the various wake-promoting agents in terms of mechanism of action, efficacy, or safety. The goal of this study was to compare amphetamine, modafinil, solriamfetol, and pitolisant at their known primary pharmacological targets, histamine H3 receptors (H3R), dopamine, norepinephrine, and serotonin transporters, and in various in vivo preclinical models in relation to neurochemistry, locomotion, behavioral sensitization, and food intake. Results confirmed that the primary pharmacological effect of amphetamine, modafinil, and solriamfetol was to increase central dopamine neurotransmission, in part by inhibiting its transporter. Furthermore, solriamfetol increased levels of extracellular dopamine in the nucleus accumbens, and decreased the 3,4-dihydroxyphenyl acetic acid (DOPAC)/DA ratio in the striatum, as reported for modafinil and amphetamine. All these compounds produced hyperlocomotion, behavioral sensitization, and hypophagia, which are common features of psychostimulants and of compounds with abuse potential. In contrast, pitolisant, a selective and potent H3R antagonist/inverse agonist that promotes wakefulness, had no effect on striatal dopamine, locomotion, or food intake. In addition, pitolisant, devoid of behavioral sensitization by itself, attenuated the hyperlocomotion induced by either modafinil or solriamfetol. Therefore, pitolisant presents biochemical, neurochemical, and behavioral profiles different from those of amphetamine and other psychostimulants such as modafinil or solriamfetol. In conclusion, pitolisant is a differentiated therapeutic option, when compared with psychostimulants, for the treatment of EDS, as this agent does not show any amphetamine-like properties within in vivo preclinical models.

The Role of BiP and the IRE1α-XBP1 Axis in Rhabdomyosarcoma Pathology

BACKGROUND

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in children, and is associated with a poor prognosis in patients presenting with recurrent or metastatic disease. The unfolded protein response (UPR) plays pivotal roles in tumor development and resistance to therapy, including RMS.

METHODS

In this study, we used immunohistochemistry and a tissue microarray (TMA) on human RMS and normal skeletal muscle to evaluate the expression of key UPR proteins (GRP78/BiP, IRE1α and cytosolic/nuclear XBP1 (spliced XBP1-sXBP1)) in the four main RMS subtypes: alveolar (ARMS), embryonal (ERMS), pleomorphic (PRMS) and sclerosing/spindle cell (SRMS) RMS. We also investigated the correlation of these proteins with the risk of RMS and several clinicopathological indices, such as lymph node involvement, distant metastasis, tumor stage and tumor scores.

RESULTS

Our results revealed that the expression of BiP, sXBP1, and IRE1α, but not cytosolic XBP1, are significantly associated with RMS (BiP and sXBP1 p-value = 0.0001, IRE1 p-value = 0.001) in all of the studied types of RMS tumors (n = 192) compared to normal skeletal muscle tissues (n = 16). In addition, significant correlations of BiP with the lymph node score (p = 0.05), and of IRE1α (p value = 0.004), cytosolic XBP1 (p = 0.001) and sXBP1 (p value = 0.001) with the stage score were observed. At the subtype level, BiP and sXBP1 expression were significantly associated with all subtypes of RMS, whereas IRE1α was associated with ARMS, PRMS and ERMS, and cytosolic XBP1 expression was associated with ARMS and SRMS. Importantly, the expression levels of IRE1α and sXBP1 were more pronounced in ARMS than in any of the other subtypes. The results also showed correlations of BiP with the lymph node score in ARMS (p value = 0.05), and of sXBP1 with the tumor score in PRMS (p value = 0.002).

CONCLUSIONS

In summary, this study demonstrates that the overall UPR is upregulated and, more specifically, that the IRE1/sXBP1 axis is active in RMS. The subtype and stage-specific dependency on the UPR machinery in RMS may open new avenues for the development of novel targeted therapeutic strategies and the identification of specific tumor markers in this rare but deadly childhood and young-adult disease.

A bioengineering method for modeling alveolar Rhabdomyosarcoma and assessing chemotherapy responses

Rhabdomyosarcoma (RMS) is the most common pediatric soft-tissue malignant tumor. Treatment of RMS usually includes primary tumor resection along with systemic chemotherapy. Two-dimensional (2D) cell culture systems and animal models have been extensively used for investigating the potential efficacy of new RMS treatments. However, RMS cells behave differently in 2D culture than in vivo, which has recently inspired the adoption of three-dimensional (3D) culture environments. In the current paper, we will describe the detailed methodology we have developed for fabricating a 3D engineered model to study alveolar RMS (ARMS) in vitro. This model consists of a thermally cross-linked collagen disk laden with RMS cells that mimics the structural and bio-chemical aspects of the tumor extracellular matrix (ECM). This process is highly reproducible and produces a 3D engineered model that can be used to analyze the cytotoxicity and autophagy induction of drugs on ARMS cells. The most improtant bullet points are as following:•

We fabricated 3D model of ARMS.

•

The current ARMS 3D model can be used for screening of chemotherapy drugs.

•

We developed methods to detect apoptosis and autophagy in ARMS 3D model to detect the mechansims of chemotherapy agents.

High-Contrast CXCR4-Targeted 18F-PET Imaging Using a Potent and Selective Antagonist

C-X-C chemokine receptor 4 (CXCR4) is highly expressed in cancers, contributing to proliferation, metastasis, and a poor prognosis. The noninvasive imaging of CXCR4 can enable the detection and characterization of aggressive cancers with poor outcomes. Currently, no ¹⁸F-labeled CXCR4 positron emission tomography (PET) radiotracer has demonstrated imaging contrast comparable to [⁶⁸Ga]Ga-Pentixafor, a CXCR4-targeting radioligand. We, therefore, aimed to develop a high-contrast CXCR4-targeting radiotracer by incorporating a hydrophilic linker and trifluoroborate radioprosthesis to LY2510924, a known CXCR4 antagonist. A carboxy-ammoniomethyl-trifluoroborate (PepBF₃) moiety was conjugated to the LY2510924-derived peptide possessing a triglutamate linker via amide bond formation to obtain BL08, whereas an alkyne ammoniomethyl-trifluoroborate (AMBF₃) moiety was conjugated using the copper-catalyzed [3+2] cycloaddition click reaction to obtain BL09. BL08 and BL09 were radiolabeled with [¹⁸F]fluoride ion using ¹⁸F-¹⁹F isotope exchange. Pentixafor was radiolabeled with [⁶⁸Ga]GaCl₃. Side-by-side PET imaging and biodistribution studies were performed on immunocompromised mice bearing Daudi Burkitt lymphoma xenografts. The biodistribution of [¹⁸F]BL08 and [¹⁸F]BL09 showed tumor uptake at 2 h postinjection (p.i.) (5.67 ± 1.25%ID/g and 5.83 ± 0.92%ID/g, respectively), which were concordant with the results of PET imaging. [¹⁸F]BL08 had low background activity, providing tumor-to-blood, -muscle, and -liver ratios of 72 ± 20, 339 ± 81, and 14 ± 3 (2 h p.i.), respectively. [¹⁸F]BL09 behaved similarly, with ratios of 64 ± 20, 239 ± 72, and 17 ± 3 (2 h p.i.), respectively. This resulted in high-contrast visualization of tumors on PET imaging for both radiotracers. [¹⁸F]BL08 exhibited lower kidney uptake (2.2 ± 0.5%ID/g) compared to [¹⁸F]BL09 (7.6 ± 1.0%ID/g) at 2 h p.i. [¹⁸F]BL08 and [¹⁸F]BL09 demonstrated higher tumor-to-blood, -muscle, and -liver ratios compared to [⁶⁸Ga]Ga-Pentixafor (18.9 ± 2.7, 95.4 ± 36.7, and 5.9 ± 0.7 at 2 h p.i., respectively). In conclusion, [¹⁸F]BL08 and [¹⁸F]BL09 enable high-contrast visualization of CXCR4 expression in Daudi xenografts. Based on high tumor-to-organ ratios, [¹⁸F]BL08 may prove a valuable new tool for CXCR4-targeted PET imaging with potential for translation. The use of a PepBF₃ moiety is a new approach for the orthogonal conjugation of organotrifluoroborates for ¹⁸F-labeling of peptides.

Designing a Rational Follow-Up Schedule for Patients with Extremity Soft Tissue Sarcoma

PURPOSE

The risk of tumor recurrence after resection of soft tissue sarcoma (STS) necessitates surveillance in follow-up. The objective of this study was to determine the frequency/timing of metastasis and local recurrence following treatment for soft tissue sarcoma, and to use these data to justify an evidence-based follow-up schedule.

METHODS

Utilizing a prospective database, a retrospective single center review was performed of all patients with minimum 2-year follow-up after resection of a localized extremity STS. Kaplan-Meier estimates were used to calculate the incidence of local recurrence and metastases on an annual basis for 10 years.

RESULTS

We identified a total of 230 low-grade, 626 intermediate-grade and 940 high-grade extremity STS and a total of 721 events, 150 local recurrences and 571 metastases. Based on tumor size and grade, follow-up cohorts were developed that had similar metastatic risk. Using pre-determined thresholds for metastatic event, a follow-up schedule was established for each cohort.

CONCLUSION

Based on our results we recommend that patients with small low-grade tumors undergo annual follow-up for 5 years following definitive local treatment. Patients with large low-grade tumors, small intermediate-grade and small high-grade tumors should have follow-up every 6 months for the first 2 years, then yearly to 10 years. Only patients with large intermediate- or high-grade tumors require follow-up every 3 months for the first 2 years, then every 6 months for years 3-5, followed by annually until 10 years.

Patient Specific Computer Modelling for Automated Sizing of Fenestrated Stent Grafts

OBJECTIVE

The aim was to validate a computational patient specific model of Zenith® fenestrated device deployment in abdominal aortic aneurysms to predict fenestration positions.

METHODS

This was a retrospective analysis of the accuracy of numerical simulation for fenestrated stent graft sizing. Finite element computational simulation was performed in 51 consecutive patients that underwent successful endovascular repair with Zenith® fenestrated stent grafts in two vascular surgery units with a high volume of aortic procedures. Longitudinal and rotational clock positions of fenestrations were measured on the simulated models. These measurements were compared with those obtained by (i) an independent observer on the post-operative computed tomography (CT) scan and (ii) by the stent graft manufacturer planning team on the pre-operative CT scan. (iii) Pre- and post-operative positions were also compared. Longitudinal distance and clock face discrepancies >3 mm and 15°, respectively, were considered significant. Reproducibility was assessed using Bland-Altman and linear regression analysis.

RESULTS

A total of 195 target arteries were analysed. Both Bland-Altman and linear regression showed good reproducibility between the three measurement techniques performed. The median absolute difference between the simulation and post-operative CT scan was 1.0 ± 1.1 mm for longitudinal distance measurements and 6.9 ± 6.1° for clock positions. The median absolute difference between the planning centre and post-operative CT scan was 0.8 ± 0.8 mm for longitudinal distance measurements and 5.1 ± 5.0° for clock positions. Finally, the median absolute difference between the simulation and the planning centre was 0.96 ± 0.97 mm for longitudinal distance measurements and 4.8 ± 3.6° for clock positions.

CONCLUSION

The numerical model of deployed fenestrated stent grafts is accurate for planning position of fenestrations. It has been validated in 51 patients, for whom fenestration locations were similar to the sizing performed by physicians and the planning centre.

Microscale radiosynthesis, preclinical imaging and dosimetry study of [18F]AMBF3-TATE: A potential PET tracer for clinical imaging of somatostatin receptors

BACKGROUND

Peptides labeled with positron-emitting isotopes are emerging as a versatile class of compounds for the development of highly specific, targeted imaging agents for diagnostic imaging via positron-emission tomography (PET) and for precision medicine via theranostic applications. Despite the success of peptides labeled with gallium-68 (for imaging) or lutetium-177 (for therapy) in the clinical management of patients with neuroendocrine tumors or prostate cancer, there are significant advantages of using fluorine-18 for imaging. Recent developments have greatly simplified such labeling: in particular, labeling of organotrifluoroborates via isotopic exchange can readily be performed in a single-step under aqueous conditions and without the need for HPLC purification. Though an automated synthesis has not yet been explored, microfluidic approaches have emerged for ¹⁸F-labeling with high speed, minimal reagents, and high molar activity compared to conventional approaches. As a proof-of-concept, we performed microfluidic labeling of an octreotate analog ([¹⁸F]AMBF₃-TATE), a promising ¹⁸F-labeled analog that could compete with [⁶⁸Ga]Ga-DOTATATE with the advantage of providing a greater number of patient doses per batch produced.

METHODS

Both [¹⁸F]AMBF₃-TATE and [⁶⁸Ga]Ga-DOTATATE were labeled, the former by microscale methods adapted from manual labeling, and were imaged in mice bearing human SSTR2-overexpressing, rat SSTR2 wildtype, and SSTR2-negative xenografts. Furthermore, a dosimetry analysis was performed for [¹⁸F]AMBF₃-TATE.

RESULTS

The micro-synthesis exhibited highly-repeatable performance with radiochemical conversion of 50 ± 6% (n = 15), overall decay-corrected radiochemical yield of 16 ± 1% (n = 5) in ~40 min, radiochemical purity >99%, and high molar activity. Preclinical imaging with [¹⁸F]AMBF₃-TATE in SSTR2 tumor models correlated well with [⁶⁸Ga]Ga-DOTATATE. The favorable biodistribution, with the highest tracer accumulation in the bladder followed distantly by gastrointestinal tissues, resulted in 1.26 × 10^-2 mSv/MBq maximal estimated effective dose in human, a value lower than that reported for current clinical ¹⁸F- and ⁶⁸Ga-labeled compounds.

CONCLUSIONS

The combination of novel chemical approaches to ¹⁸F-labeling and microdroplet radiochemistry have the potential to serve as a platform for greatly simplified development and production of ¹⁸F-labeled peptide tracers. Favorable preclinical imaging and dosimetry of [¹⁸F]AMBF₃-TATE, combined with a convenient synthesis, validate this assertion and suggest strong potential for clinical translation.

The challenges of managing degree apprentices in the workplace

Purpose

The purpose of this paper is to explore the issues and challenges facing employers as they manage degree apprentices in the workplace. It examines the relationship between managers and apprentices undertaking a work-based degree. This research is of particular relevance at this time because of the UK Government’s initiative to expand the number of apprenticeships in the workplace to three million new starts by 2020, inevitably bringing a range of pressures to bear on employers (BIS, 2015). The purpose is to share early experiences of employer management of degree apprenticeships, and provide a range of recommendations to develop and improve employer and higher education institution (HEI) practice.

Design/methodology/approach

This paper combines desk research with qualitative data drawn from interviews with a range of cross-sector organisations to investigate the employer’s experience of developing the new degree apprenticeships. Data are explored inductively using thematic analysis in order to surface dominant patterns and considers the implications of findings upon current and emerging HEI and employer practice and research.

Findings

There were a number of key themes which emerged from the data collected. These included the need for effective, employer-led recruitment processes, careful management of expectations, sound HEI retention strategies, employer involvement and board-level motivators to ensure organisational benefits are derived from effectively situated workplace learning and a focus upon effective, empowering mentoring and support strategies.

Research limitations/implications

As degree apprenticeship standards and programmes are currently at the early stages of implementation, and opportunities, funding and resourcing are rapidly changing in the context of government policy, so too will employer appetite and strategies for supporting degree apprentices, along with apprentice behaviour. This means that additional findings, beyond those highlighted within this paper, may emerge in the near future.

Practical implications

There are a number of practical implications supporting managerial development and support of degree apprentices in the workplace from this research. These are reflected in the findings, and include the development of flexible and collaborative processes, resources, mentor training and networks.

Originality/value

This paper is one of the first published accounts of the employers’ perspective of managing a degree apprenticeship within the new policy context in the UK. As a result, the work offers a unique insight into the emerging challenges and issues encountered by managers working with degree apprentices in the twenty-first century business environment.

Impact of Multileaf Collimator Configuration Parameters on the Dosimetric Accuracy of 6-MV Intensity-Modulated Radiation Therapy Treatment Plans

The purpose of this study was to evaluate the impact of selected configuration parameters that govern multileaf collimator (MLC) transmission and rounded leaf offset in a commercial treatment planning system (TPS) (Pinnacle³, Philips Medical Systems, Andover, MA, USA) on the accuracy of intensity-modulated radiation therapy (IMRT) dose calculation. The MLC leaf transmission factor was modified based on measurements made with ionization chambers. The table of parameters containing rounded-leaf-end offset values was modified by measuring the radiation field edge as a function of leaf bank position with an ionization chamber in a scanning water-tank dosimetry system and comparing the locations to those predicted by the TPS. The modified parameter values were validated by performing IMRT quality assurance (QA) measurements on 19 gantry-static IMRT plans. Planar dose measurements were performed with radiographic film and a diode array (MapCHECK2) and compared to TPS calculated dose distributions using default and modified configuration parameters. Based on measurements, the leaf transmission factor was changed from a default value of 0.001 to 0.005. Surprisingly, this modification resulted in a small but statistically significant worsening of IMRT QA gamma-index passing rate, which revealed that the overall dosimetric accuracy of the TPS depends on multiple configuration parameters in a manner that is coupled and not intuitive because of the commissioning protocol used in our clinic. The rounded leaf offset table had little room for improvement, with the average difference between the default and modified offset values being -0.2 ± 0.7 mm. While our results depend on the current clinical protocols, treatment unit and TPS used, the methodology used in this study is generally applicable. Different clinics could potentially obtain different results and improve their dosimetric accuracy using our approach.

Patient-specific simulation of endovascular repair surgery with tortuous aneurysms requiring flexible stent-grafts

The rate of post-operative complications is the main drawback of endovascular repair, a technique used to treat abdominal aortic aneurysms. Complex anatomies, featuring short aortic necks and high vessel tortuosity for instance, have been proved likely prone to these complications. In this context, practitioners could benefit, at the preoperative planning stage, from a tool able to predict the post-operative position of the stent-graft, to validate their stent-graft sizing and anticipate potential complications. In consequence, the aim of this work is to prove the ability of a numerical simulation methodology to reproduce accurately the shapes of stent-grafts, with a challenging design, deployed inside tortuous aortic aneurysms. Stent-graft module samples were scanned by X-ray microtomography and subjected to mechanical tests to generate finite-element models. Two EVAR clinical cases were numerically reproduced by simulating stent-graft models deployment inside the tortuous arterial model generated from patient pre-operative scan. In the same manner, an in vitro stent-graft deployment in a rigid polymer phantom, generated by extracting the arterial geometry from the preoperative scan of a patient, was simulated to assess the influence of biomechanical environment unknowns in the in vivo case. Results were validated by comparing stent positions on simulations and post-operative scans. In all cases, simulation predicted stents deployed locations and shapes with an accuracy of a few millimetres. The good results obtained in the in vitro case validated the ability of the methodology to simulate stent-graft deployment in very tortuous arteries and led to think proper modelling of biomechanical environment could reduce the few local discrepancies found in the in vivo case. In conclusion, this study proved that our methodology can achieve accurate simulation of stent-graft deployed shape even in tortuous patient specific aortic aneurysms and may be potentially helpful to help practitioners plan their intervention.

A method for selecting modified DNAzymes without the use of modified DNA as a template in PCR

Modified DNAzyme selections typically depend on recopying catalytically active modified DNA (mDNA) into cDNA in a PCR amplification step. However mDNA is often a poor template in PCR. Herein we propose a selection method in which the catalytically active, mDNA strand is covalently linked to the unmodified DNA template strand from which it was polymerized. Following selection, the unmodified DNA template is amplified in a PCR instead of the mDNA. This method circumvents the PCR amplification of mDNA.

Patient-specific numerical simulation of stent-graft deployment: Validation on three clinical cases

Endovascular repair of abdominal aortic aneurysms faces some adverse outcomes, such as kinks or endoleaks related to incomplete stent apposition, which are difficult to predict and which restrain its use although it is less invasive than open surgery. Finite element simulations could help to predict and anticipate possible complications biomechanically induced, thus enhancing practitioners' stent-graft sizing and surgery planning, and giving indications on patient eligibility to endovascular repair. The purpose of this work is therefore to develop a new numerical methodology to predict stent-graft final deployed shapes after surgery. The simulation process was applied on three clinical cases, using preoperative scans to generate patient-specific vessel models. The marketed devices deployed during the surgery, consisting of a main body and one or more iliac limbs or extensions, were modeled and their deployment inside the corresponding patient aneurysm was simulated. The numerical results were compared to the actual deployed geometry of the stent-grafts after surgery that was extracted from postoperative scans. We observed relevant matching between simulated and actual deployed stent-graft geometries, especially for proximal and distal stents outside the aneurysm sac which are particularly important for practitioners. Stent locations along the vessel centerlines in the three simulations were always within a few millimeters to actual stents locations. This good agreement between numerical results and clinical cases makes finite element simulation very promising for preoperative planning of endovascular repair.

Deployment of stent grafts in curved aneurysmal arteries: toward a predictive numerical tool

The mechanical behavior of aortic stent grafts plays an important role in the success of endovascular surgery for aneurysms. In this study, finite element analysis was carried out to simulate the expansion of five marketed stent graft iliac limbs and to evaluate quantitatively their mechanical performances. The deployment was modeled in a simplified manner according to the following steps: (i) stent graft crimping and insertion in the delivery sheath, (ii) removal of the sheath and stent graft deployment in the aneurysm, and (iii) application of arterial pressure. In the most curved aneurysm and for some devices, a decrease of stent graft cross-sectional area up to 57% was found at the location of some kinks. Apposition defects onto the arterial wall were also clearly evidenced and quantified. Aneurysm inner curve presented significantly more apposition defects than outer curve. The feasibility of finite element analysis to simulate deployment of marketed stent grafts in curved aneurysm models was demonstrated. The study of the influence of aneurysm tortuosity on stent graft mechanical behavior shows that increasing vessel curvature leads to stent graft kinks and inadequate apposition against the arterial wall. Such simulation approach opens a very promising way toward surgical planning tools able to predict intra and/or post-operative short-term stent graft complications.

Preclinical evaluation of the abuse potential of Pitolisant, a histamine H₃ receptor inverse agonist/antagonist compared with Modafinil

BACKGROUND AND PURPOSE

Pitolisant, a histamine H₃ receptor inverse agonist/antagonist is currently under Phase III clinical trials for treatment of excessive daytime sleepiness namely in narcoleptic patients. Its drug abuse potential was investigated using in vivo models in rodents and monkeys and compared with those of Modafinil, a psychostimulant currently used in the same indications.

EXPERIMENTAL APPROACH

Effects of Pitolisant on dopamine release in the nucleus accumbens, on spontaneous and cocaine-induced locomotion, locomotor sensitization were monitored. It was also tested in three standard drug abuse tests i.e. conditioned place preference in rats, self-administration in monkeys and cocaine discrimination in mice as well as in a physical dependence model.

KEY RESULTS

Pitolisant did not elicit any significant changes in dopaminergic indices in rat nucleus accumbens whereas Modafinil increased dopamine release. In rodents, Pitolisant was without any effect on locomotion and reduced the cocaine-induced hyperlocomotion. In addition, no locomotor sensitization and no conditioned hyperlocomotion were evidenced with this compound in rats whereas significant effects were elicited by Modafinil. Finally, Pitolisant was devoid of any significant effects in the three standard drug abuse tests (including self-administration in monkeys) and in the physical dependence model.

CONCLUSIONS AND IMPLICATIONS

No potential drug abuse liability for Pitolisant was evidenced in various in vivo rodent and primate models, whereas the same does not seem so clear in the case of Modafinil.

[Triggers of bulimia and compulsion attacks: validation of the "Start" questionnaire]

AIM

There are few published studies on the triggers of binge eating in anorexia nervosa of binge/purging subtype (BPAN), bulimia nervosa (BN) and binge eating disorder (BED).

PATIENTS AND METHODS

We validated in 29 patients (10 BPAN, 10 BN and 9 BED) the perspicuity, the clarity and the intra- (doubles) and inter- (test-retest) reproducibility of a 24-item Start questionnaire on the triggers of binge eating. Then the Start questionnaire was administered to 176 patients (65 BPAN, 62 BN and 59 BED patients) being 27.5+9.1 yr old, having 15+9 binge eating (BE) episodes/week, with a mean binge duration of 1 hr 36min (+ 38min)/day.

RESULTS

BE episodes occurred mainly during the second part of the day: afternoon after work (67% of the patients), "tea" time (55%), evening after dinner (42%) and at night (22%). The principal place for BE episodes was at home (96%). The BED patients avoided binges at the parents' home (89%) more often than the BPAN (62%, P<0.02). The binges occurred mainly in the living room (44%), in the kitchen (43%), and less in the bedroom (31%). Hunger pangs seemed to be a trigger of binges in 31% of the patients, and a stronger trigger in BED (42%) than in the BPAN and BN patients (24%; P=0.04). Binge eating episodes could occur despite a high satiety level (just after lunch or dinner) in 29% of the BN and in 16% of the BED patients (P<0.02). Concerning food, the major triggers were high energy-density food (77%) and comfort food (60%), such as chocolate, cakes, bread and pasta. The food consumed for binge episodes (in-binge food) was more often a strong trigger than the other food (not used for binges): olfaction (19% versus 10%), sight (52% versus 25%) and placing in the mouth (71% versus 26%; P<0.02 for all, in the 3 groups). Being tired could be a strong trigger in 37% of the patients, but "being aroused" in the other 38 % of the patients. Stressful events (65%), anxiety (74%), "being under pressure" or irritated (51% and 55%) were of course major triggers in a majority of the patients, as well as sadness (61%), feeling of powerlessness (62%), inefficiency (73%) and depressive state (71%). Flashback from traumatism (sexual trauma in 17% of the patients) was a strong trigger of binges more often in BPAN and BED (44%) than in BN (23%; P<0.05). The binge eating was painful (and "not at all a pleasure") in 69% of the patients, but could also be a relaxing behavior in 31% of the patients, more often in the BED (43%) than in the BPAN patients (20%; P<0.05). The binge eating behavior was quoted as obsessive in 63% of BPAN, 92% of BN and only 34% of BED patients (P<0.001). The patients said that they were unable to avoid the binge (76% of the patients), more often in BPAN and BN than in BED patients (P<0.01). As a whole, 62% of BPAN, 89% of BN and only 4 % of BED patients (P<0.05) were unable to avoid purging (vomiting). In 12% of the cases, there was a pleasure felt when binging. For the other patients, shame, filth and incapacity were the feelings related to binges in 58% of the BPAN, 45% of BN and 43% of BED patients (P<0.04). The global score of addiction (zero=not addicted, 10=very addicted) was 8.56+1.2 in BPAN, 8.42+1.5 in BN and 6.74+1.1 in BED patients (NS between BPAN and BN; P<0.01 between BPAN and BN on the one hand and BED on the other).

CONCLUSION

The present study has demonstrated the usefulness of the Start questionnaire. It also evidences the key role of intrinsic factors, both metabolic and emotional, as strong triggers for binge eating episodes in BPAN, BN and BED. It has also demonstrated the role of environmental determinants.

In vitro selection of a DNAzyme with three modified nucleotides

Three modified nucleosides have been used in the in vitro selection of the self-cleaving DNAzyme 9-33. This DNAzyme operates in the absence of divalent metal cations with a first-order constant of approximately 0.05 min(-1).

Enhanced cAMP production mediates the stimulatory action of pituitary adenylate cyclase activating polypeptide (PACAP) on in vitro catecholamine secretion from bovine adrenal chromaffin cells

The 38 amino acid peptide pituitary adenylate cyclase activating polypeptide (PACAP) induced a dose dependent increase of catecholamine secretion in cultures of bovine chromaffin cells. This secretagogue activity of PACAP was strictly dependent on the presence of calcium in the culture medium. If calcium was omitted from the medium no effect of PACAP on catecholamine secretion could be detected during an incubation of 20 min. Preincubation of cells with 1 nM PACAP for 5 min facilitated the subsequent nicotine stimulated catecholamine secretion during a 20 min incubation without addition of the peptide. PACAP induced catecholamine secretion was clearly accompanied by a dose dependent increase of intracellular cAMP concentrations. The percentage of cells responding to PACAP with increased catecholamine secretion was assessed by immunocytochemistry of the transient appearance of dopamine-beta-hydroxylase, associated with the membranes of the chromaffin granules on the cell surface during the secretory process. About 70% of adrenal medullary cells responded to 100 nM PACAP with enhanced secretory activity. Though PACAP stimulated catecholamine secretion, we did not observed major effects on intracellular free calcium concentrations ([Ca2+]i) as determined with fura-2 by single cell fluorescence microscopy. In maximally 20% of the cells a rise in [Ca2+]i in response to a challenge with 500 nM PACAP was observed. Lower concentrations of PACAP were without an effect on [Ca2+]i. These data indicate that the stimulatory action of PACAP on in vitro catecholamine secretion from bovine chromaffin cells is linked to a rise of intracellular cAMP.

The stimulatory effect of pituitary adenylate cyclase activating polypeptide (PACAP) on LH release from rat pituitary cells in vitro does not involve calcium mobilization

The hypothalamic peptide "pituitary adenylate cyclase activating polypeptide (PACAP)" stimulates cAMP production in cultured rat pituitary cells and enhances LH release. It has been suggested that the stimulation of LH release by PACAP comprises two distinct mechanisms: a direct stimulatory action on LH secretion and a potentiation of the response of the gonadotrophes to LHRH. Thus the possibility exists that PACAP may enhance LH secretion not only by increased cAMP production but also by increasing cytosolic Ca2+ concentrations ([Ca2+]). In the present study we examined whether PACAP affects cytosolic [Ca2+] in identified rat gonadotrophes (as determined by the fura-method) and whether the suggested potentiating effect of PACAP on LHRH induced LH release is dependent on Ca2+. PACAP (1 nM) and 0.1 nM LHRH significantly increased LH concentrations in the culture medium after 5 hrs of incubation. Coincubation of cells with both peptides resulted in an additive increase of LH release. While the stimulatory effect LHRH was blunted in Ca(2+)-free medium, PACAP remained stimulatory to LH release. PACAP stimulated cAMP formation regardless whether the culture medium contained Ca2+ or not. Gonadotrophes were selected by their response to LHRH (1 microM) and were subsequently challenged with PACAP (1 microM). About 75% of gonadotrophes responded also to PACAP with an increase of cytosolic [Ca2+] which was blunted by removal of extracellular Ca2+. We suggest that in the rat pituitary the majority of the gonadotrophes are PACAP responsive as determined by an increase of cytosolic [Ca2+].(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of aging on brain-derived neurotrophic factor, proBDNF, and their receptors in the hippocampus of Lou/C rats

The interest in understanding healthy aging has prompted scientist to look for animal models presenting this feature. Lou/C rats, an inbred strain of Wistar origin, is an animal model of successful aging with a longer lifespan and preserved memory capacities than most laboratory rat strains. In an attempt to shed light on this remarkable aging feature, we investigated the hippocampal patterns (mRNA and proteins) of some protective and plasticity-related molecules, i.e., brain-derived neurotrophic factor (BDNF), its precursor proBDNF, and its receptors (i.e., TrkB.FL, TrkB.T1, TrkB.T2, and p75). Using different experimental approaches, we compared these characteristics in young and aged Lou/C versus matched Wistar rats (the most appropriate controls). Data showed that young and aged Lou/C rats had higher amounts of BDNF and proBDNF content than Wistar rats. In contrast, proBDNF content was reduced in aged Lou/C rats and increased in aged Wistar rats. With aging, Lou/C rats showed a weaker decrease in TrkB.FL receptors than Wistar rats and no changes in TrkB.T1 receptors, which, contrarily, were increased in aged Wistar rats. Overall, these observations could account for the preserved cognitive performances and memory-dependent mechanisms, such as the unaltered long-term potentiation (LTP), throughout the lifespan recently reported in the Lou/C strain. Data suggest that boosting the expression or activity of these endogenous protective systems may be a promising alternative for combating some age-related cognitive declines. Therefore, Lou/C rats represent an interesting model of healthy aging for studying plasticity-related processes that evolve from youthfulness to aging.

Prenatal nicotine alters maturation of breathing and neural circuits regulating respiratory control

While perinatal nicotine effects on ventilation have been widely investigated, the prenatal impact of nicotine treatment during gestation on both breathing and neural circuits involved in respiratory control remains unknown. We examined the effects of nicotine, from embryonic day 5 (E5) to E20, on baseline ventilation, the two hypoxic ventilatory response components and in vivo tyrosine hydroxylase (TH) activity in carotid bodies and brainstem areas, assessed at postnatal day 7 (P7), P11 and P21. In pups prenatally exposed to nicotine, baseline ventilation and hypoxic ventilatory response were increased at P7 (+48%) and P11 (+46%), with increased tidal volume (p<0.05). Hypoxia blunted frequency response at P7 and revealed unstable ventilation at P11. In carotid bodies, TH activity increased by 20% at P7 and decreased by 48% at P11 (p<0.05). In most brainstem areas it was reduced by 20-33% until P11. Changes were resolved by P21. Prenatal nicotine led to postnatal ventilatory sequelae, partly resulting from impaired maturation of peripheral chemoreceptors and brainstem integrative sites.

Developmental plasticity of the carotid chemoafferent pathway in rats that are hypoxic during the prenatal period

The chemoreflex pathway undergoes postnatal maturation, and the perinatal environment plays a critical role in shaping respiratory control system. We investigated the role of prenatal hypoxia on the maturation of the chemoreflex neural circuits regulating ventilation in rat. Effects of hypoxia (10% O2) from the 5th to the 20th day of gestation were studied on male offspring at birth and on postnatal days 3, 7, 21 and 68. Maturation of the respiratory control system was assessed by in vivo tyrosine hydroxylase (TH) activity measurement in peripheral chemoreceptors (carotid bodies, petrosal ganglia), and in brainstem catecholaminergic cell groups (A2C2c and A1C1 areas in the medulla, A5 and A6 areas in the pons). Resting ventilation and ventilatory response to hypoxia were evaluated as functional sequelae. In peripheral structures, prenatal hypoxia reduced TH activity within the first postnatal week and enhanced it later. In contrast, in central areas, prenatal hypoxia upregulated TH activity within the first postnatal week and downregulated it later. The in vivo TH activity impairment is therefore tissue specific, with an opposite effect on the peripheral and central neural circuits. A shift of the effect of prenatal hypoxia occurred between 1 and 3 weeks, indicating a postnatal temporal effect of prenatal hypoxia. An important period in the development of the chemoafferent pathway occurred between the first and the third postnatal week. Functionally, prenatal hypoxia impaired resting ventilation and ventilatory response to hypoxia. The alterations of the catecholaminergic components of the chemoafferent pathway resulting from prenatal hypoxia might contribute to impair postnatal respiratory behaviour.

Optimizing a recycling process of SMC composite waste

Investigations about the recycling of sheet moulding compounds (SMC) waste as incorporation material for thermoplastic polymer matrix are reported in this paper. A new efficient process is developed in order to strongly increase the reinforcement glass fraction of SMC leading to good mechanical performance of the new thermoplastic compounds. The overall process is composed of two main steps: mechanical and chemical. The second stage is characterised in terms of optimization and capability by means of experimental design and statistical process control techniques for finding the optimal chemical conditions and validating the process.

[Spontaneous uterine rupture of an unscarred uterus during labor: case report and review of the literature]

Uterine rupture during labor is a serious and uncommon obstetrical complication that can lead to severe prognosis for the mother and her child if not immediately diagnosed and treated. Most spontaneous uterine ruptures occur during labor in parturients with a scarred uterus and are much rarer on an unscarred uterus. We report the case of a uterine rupture on unscarred uterus to a 32 year-old woman after a labor induced by intravaginal prostaglandin and intravenous ocytocine injection. Our management is compared with the data from literature.

Brain histamine and schizophrenia: potential therapeutic applications of H3-receptor inverse agonists studied with BF2.649

BF2.649, a high affinity and selective non-imidazole histamine H(3)-receptor antagonist/inverse agonist, was found to easily enter the brain after oral administration to mice: it displayed a ratio of brain/plasma levels of about 25 when considering either C(max) or AUC values. At low oral doses (2.5-20mg/kg), it elicited in mice a dose-dependent wakening effect accompanied with a shift towards high frequency waves of the EEG, a sign of cortical activation. DOPAC/dopamine ratios were enhanced in the prefrontal cortex but not in the striatum, indicating a selective activation of a sub-population of dopaminergic neurons. BF2.649 showed significant inhibitory activity in several mouse models of schizophrenia. It reduced locomotor hyperactivity elicited by methamphetamine or dizolcipine without significantly affecting spontaneous locomotor activity when administered alone. It also abolished the apomorphine-induced deficit in prepulse inhibition. These observations suggest that H(3)-receptor inverse agonists/antagonists deserve attention as a novel class of antipsychotic drugs endowed with pro-cognitive properties.