Hampshire Sheep as a Large-Animal Model for Cochlear Implantation.

BACKGROUND: Sheep have been proposed as a large-animal model for studying cochlear implantation. However, prior sheep studies report that the facial nerve (FN) obscures the round window membrane (RWM), requiring FN sacrifice or a retrofacial opening to access the middle-ear cavity posterior to the FN for cochlear implantation. We investigated surgical access to the RWM in Hampshire sheep compared to Suffolk-Dorset sheep and the feasibility of Hampshire sheep for cochlear implantation via a facial recess approach. METHODS: Sixteen temporal bones from cadaveric sheep heads (ten Hampshire and six Suffolk-Dorset) were dissected to gain surgical access to the RWM via an extended facial recess approach. RWM visibility was graded using St. Thomas' Hospital (STH) classification. Cochlear implant (CI) electrode array insertion was performed in two Hampshire specimens. Micro-CT scans were obtained for each temporal bone, with confirmation of appropriate electrode array placement and segmentation of the inner ear structures. RESULTS: Visibility of the RWM on average was 83% in Hampshire specimens and 59% in Suffolk-Dorset specimens (p = 0.0262). Hampshire RWM visibility was Type I (100% visibility) for three specimens and Type IIa (> 50% visibility) for seven specimens. Suffolk-Dorset RWM visibility was Type IIa for four specimens and Type IIb (< 50% visibility) for two specimens. FN appeared to course more anterolaterally in Suffolk-Dorset specimens. Micro-CT confirmed appropriate CI electrode array placement in the scala tympani without apparent basilar membrane rupture. CONCLUSIONS: Hampshire sheep appear to be a suitable large-animal model for CI electrode insertion via an extended facial recess approach without sacrificing the FN. In this small sample, Hampshire specimens had improved RWM visibility compared to Suffolk-Dorset. Thus, Hampshire sheep may be superior to other breeds for ease of cochlear implantation, with FN and facial recess anatomy more similar to humans.

An Implantable Piezofilm Middle Ear Microphone: Performance in Human Cadaveric Temporal Bones.

PURPOSE: One of the major reasons that totally implantable cochlear microphones are not readily available is the lack of good implantable microphones. An implantable microphone has the potential to provide a range of benefits over external microphones for cochlear implant users including the filtering ability of the outer ear, cosmetics, and usability in all situations. This paper presents results from experiments in human cadaveric ears of a piezofilm microphone concept under development as a possible component of a future implantable microphone system for use with cochlear implants. This microphone is referred to here as a drum microphone (DrumMic) that senses the robust and predictable motion of the umbo, the tip of the malleus. METHODS: The performance was measured by five DrumMics inserted in four different human cadaveric temporal bones. Sensitivity, linearity, bandwidth, and equivalent input noise were measured during these experiments using a sound stimulus and measurement setup. RESULTS: The sensitivity of the DrumMics was found to be tightly clustered across different microphones and ears despite differences in umbo and middle ear anatomy. The DrumMics were shown to behave linearly across a large dynamic range (46 dB SPL to 100 dB SPL) across a wide bandwidth (100 Hz to 8 kHz). The equivalent input noise (over a bandwidth of 0.1-10 kHz) of the DrumMic and amplifier referenced to the ear canal was measured to be about 54 dB SPL in the temporal bone experiment and estimated to be 46 dB SPL after accounting for the pressure gain of the outer ear. CONCLUSION: The results demonstrate that the DrumMic behaves robustly across ears and fabrication. The equivalent input noise performance (related to the lowest level of sound measurable) was shown to approach that of commercial hearing aid microphones. To advance this demonstration of the DrumMic concept to a future prototype implantable in humans, work on encapsulation, biocompatibility, and connectorization will be required.

Sheep as a Large-Animal Model for Otology Research: Temporal Bone Extraction and Transmastoid Facial Recess Surgical Approach.

PURPOSE: Sheep are used as a large-animal model for otology research and can be used to study implantable hearing devices. However, a method for temporal bone extraction in sheep, which enables various experiments, has not been described, and literature on middle ear access is limited. We describe a method for temporal bone extraction and an extended facial recess surgical approach to the middle ear in sheep. METHODS: Ten temporal bones from five Hampshire sheep head cadavers were extracted using an oscillating saw. After craniotomy and removal of the brain, a coronal cut was made at the posterior aspect of the orbit followed by a midsagittal cut of the occipital bone and disarticulation of the atlanto-occipital joint. Temporal bones were surgically prepared with an extended facial recess approach. Micro-CT scans of each temporal bone were obtained, and anatomic dimensions were measured. RESULTS: Temporal bone extraction was successful in 10/10 temporal bones. Extended facial recess approach exposed the malleus, incus, stapes, and round window while preserving the facial nerve, with the following surgical considerations: minimally pneumatized mastoid; tegmen (superior limit of mastoid cavity) is low-lying and sits below temporal artery; chorda tympani sacrificed to optimize middle ear exposure; incus buttress does not obscure view of middle ear. Distance between the superior aspect of external auditory canal and tegmen was 2.7 (SD 0.9) mm. CONCLUSION: We identified anatomic landmarks for temporal bone extraction and describe an extended facial recess approach in sheep that exposes the ossicles and round window. This approach is feasible for studying implantable hearing devices.

The UmboMic: A PVDF Cantilever Microphone.

Objective: We present the "UmboMic," a prototype piezoelectric cantilever microphone designed for future use with totally-implantable cochlear implants. Methods: The UmboMic sensor is made from polyvinylidene difluoride (PVDF) because of its low Young's modulus and biocompatibility. The sensor is designed to fit in the middle ear and measure the motion of the underside of the eardrum at the umbo. To maximize its performance, we developed a low noise charge amplifier in tandem with the UmboMic sensor. This paper presents the performance of the UmboMic sensor and amplifier in fresh cadaveric human temporal bones. Results: When tested in human temporal bones, the UmboMic apparatus achieves an equivalent input noise of 32.3 dB SPL over the frequency range 100 Hz to 7 kHz, good linearity, and a flat frequency response to within 10 dB from about 100 Hz to 6 kHz. Conclusion: These results demonstrate the feasibility of a PVDF-based microphone when paired with a low-noise amplifier. The reported UmboMic apparatus is comparable in performance to a conventional hearing aid microphone. Significance: The proof-of-concept UmboMic apparatus is a promising step towards creating a totally-implantable cochlear implant. A completely internal system would enhance the quality of life of cochlear implant users.

Scalable Self-Limiting Dielectrophoretic Trapping for Site-Selective Assembly of Nanoparticles.

The absence of a versatile, scalable, and defect-free bottom-up assembly of nanoparticles with high precision has been a longstanding roadblock facing the large-scale integration of diverse nanoparticle-based devices. To circumvent this roadblock, we present a self-limiting dielectrophoretic approach to precisely align nanoparticles onto an array of electrodes over a large area, assisted by lithographically defined capacitors in series with the electrodes. We have experimentally verified that the on-chip capacitor can reduce the probability of trapping multiple particles at a given site, as the electric field is greatly weakened after the first nanoparticle bridges the electrodes. A 70% yield of single-nanowire assembly has been achieved, and key factors limiting the current yield are discussed. The yield is expected to further increase by improving the nanoparticle-electrode contact and reducing the capillary force during the drying process. We also demonstrate the versatility of this approach for scalable and site-selective alignment of various nanoparticles.

A versatile acoustically active surface based on piezoelectric microstructures.

We demonstrate a versatile acoustically active surface consisting of an ensemble of piezoelectric microstructures that are capable of radiating and sensing acoustic waves. A freestanding microstructure array embossed in a single step on a flexible piezoelectric sheet of polyvinylidene fluoride (PVDF) leads to high-quality acoustic performance, which can be tuned by the design of the embossed microstructures. The high sensitivity and large bandwidth for sound generation demonstrated by this acoustically active surface outperform previously reported thin-film loudspeakers using PVDF, PVDF copolymers, or voided charged polymers without microstructures. We further explore the directivity of this device and its use on a curved surface. In addition, high-fidelity sound perception is demonstrated by the surface, enabling its microphonic application for voice recording and speaker recognition. The versatility, high-quality acoustic performance, minimal form factor, and scalability of future production of this acoustically active surface can lead to broad industrial and commercial adoption for this technology.

Molecular Platform for Fast Low-Voltage Nanoelectromechanical Switching.

The use of molecules as active components to build nanometer-scale devices inspires emerging device concepts that employ the intrinsic functionality of molecules to address longstanding challenges facing nanoelectronics. Using molecules as controllable-length nanosprings, here we report the design and operation of a nanoelectromechanical (NEM) switch which overcomes the typical challenges of high actuation voltages and slow switching speeds for previous NEM technologies. Our NEM switches are hierarchically assembled using a molecular spacer layer sandwiched between atomically smooth electrodes, which defines a nanometer-scale electrode gap and can be electrostatically compressed to repeatedly modulate the tunneling current. The molecular layer and the top electrode structure serve as two degrees of design freedom with which to independently tailor static and dynamic device characteristics, enabling simultaneous low turn-on voltages (sub-3 V) and short switching delays (2 ns). This molecular platform with inherent nanoscale modularity provides a versatile strategy for engineering diverse high-performance and energy-efficient electromechanical devices.

Hybrid Approach to Fabricate Uniform and Active Molecular Junctions.

Molecules can serve as ultimate building blocks for extreme nanoscale devices. This requires their precise integration into functional heterojunctions, most commonly in the form of metal-molecule-metal architectures. Structural damage and nonuniformities caused by current fabrication techniques, however, limit their effective incorporation. Here, we present a hybrid fabrication approach enabling uniform and active molecular junctions. A template-stripping technique is developed to form electrodes with sub-nanometer smooth surfaces. Combined with dielectrophoretic trapping of colloidal nanorods, uniform sub-5 nm junctions are achieved. Uniquely, in our design, the top contact is mechanically free to move under an applied stimulus. Using this, we investigate the electromechanical tuning of the junction and its tunneling conduction. Here, the molecules help control sub-nanometer mechanical modulation, which is conventionally challenging due to instabilities caused by surface adhesive forces. Our versatile approach provides a platform to develop and study active molecular junctions for emerging applications in electronics, plasmonics, and electromechanical devices.

Gharial nesting in a reservoir is limited by reduced river flow and by increased bank vegetation.

The gharial (Gavialis gangeticus Gmelin) is a fish-eating specialist crocodylian, endemic to south Asia, and critically endangered in its few remaining wild localities. A secondary gharial population resides in riverine-reservoir habitat adjacent to the Nepal border, within the Katerniaghat Wildlife Sanctuary (KWS), and nests along a 10 km riverbank of the Girwa River. A natural channel shift in the mainstream Karnali River (upstream in Nepal) has reduced seasonal flow in the Girwa stretch where gharials nest, coincident with a gradual loss of nest sites, which in turn was related to an overall shift to woody vegetation at these sites. To understand how these changes in riparian vegetation on riverbanks were related to gharial nesting, we sampled vegetation at these sites from 2017 to 2019, and derived an Enhanced Vegetation Index (EVI) from LANDSAT 8 satellite data to quantify riverside vegetation from 1988 through 2019. We found that sampled sites transitioned to woody cover, the number of nesting sites declined, and the number of nests were reduced by > 40%. At these sites, after the channel shift, woody vegetation replaced open sites that predominated prior to the channel shift. Our findings indicate that the lack of open riverbanks and the increase in woody vegetation at potential nesting sites threatens the reproductive success of the KWS gharial population. This population persists today in a regulated river ecosystem, and nests in an altered riparian habitat which appears to be increasingly unsuitable for the continued successful recruitment of breeding adults. This second-ranking, critically endangered remnant population may have incurred an "extinction debt" by living in a reservoir that will lead to its eventual extirpation.

An Implantable Umbo Microphone For Fully-Implantable Assistive Hearing Devices.

This paper presents an implantable microphone for sensing the displacement of the umbo, the end of the malleus where it attaches to the center tip of the cone-shaped tympanic membrane. The sensor comprises a piezoelectric polyvinylidene fluoride (PVDF) film with copper-nickel electrodes suspended across a brass cylinder. The cylinder is oriented so that the umbo pushes on the film center, causing a static and acoustically-driven dynamic film displacement. An amplifier filters the resulting piezoelectric charge to produce an output signal. The sensor enables the full implantation of assistive hearing devices, which can restore hearing without inhibiting the user's lifestyle, while enabling better sound localization in noisy environments.

Precision pH Sensor Based on WO3 Nanofiber-Polymer Composites and Differential Amplification.

We report a new type of potentiometric pH sensor with sensitivity exceeding the theoretical Nernstian behavior (-59.1 mV/pH). For the pH-sensitive electrode, 1D tungsten oxide (WO3) nanofibers (NFs) were prepared to obtain large surface area and high porosity. These NFs were then stabilized in a reactive porous chloromethylated triptycene poly(ether sulfone) (Cl-TPES) binder, to facilitate proton diffusion into the polymer membrane. The measurements were performed with a differential amplifier using matched MOSFETs and providing a 10-fold amplified signal over a simple potentiometric determination. A high pH sensitivity of -377.5 mV/pH and a linearity of 0.9847 were achieved over the pH range of 6.90-8.94. Improved signal-to-noise ratios with large EMF signal changes of 175 mV were obtained in artificial seawater ranging pH 8.07-7.64 (ΔpH = 0.43), which demonstrates a practical application for pH monitoring in ocean environments.

Eggshell structure in Caiman latirostris eggs improves embryo survival during nest inundation.

Egg inundation often results in poor hatching success in crocodylians. However, how tolerant eggs are to submergence, and/or how eggshell ultrastructure may affect embryo survival when inundated, are not well understood. In this study, our objective was to determine if embryo survival in Caiman latirostris is affected by eggshell surface roughness, when eggs are submerged under water. Tolerance to inundation was tested early (day 30) versus late (day 60) in development, using eight clutches (four per time treatments), subdivided into four groups: (N = 9 per clutch per treatment; 9 × 4 = 36 eggs per group). 'Rough' eggshell represented the natural, unmodified eggshell surface structure. 'Smooth' eggshell surface structure was created by mechanically sanding the natural rough surface to remove surface columnar elements and secondary layer features, e.g. irregularities that result in 'roughness'. When inundated by submerging eggs under water for 10 h at day 30, 'smooth' eggshell structure resulted in more than twice as many dead embryos (16 versus 6, smooth versus rough; N = 36), and fewer than half as many healthy embryos (6 versus 13, smooth versus rough, respectively; N = 36). By contrast, at day 60, inundation resulted in very low hatching success, regardless of eggshell surface structure. Only two hatchlings survived the inundation, notably in the untreated group with intact, rough eggshells. Inundation produced a high rate of malformations (58% at day 30), but did not affect hatchling size. Our results indicate that eggshell roughness enhances embryo survival when eggs are inundated early in development, but not late in development. Apparently, the natural surface 'roughness' entraps air bubbles at the eggshell surface during inundation, thereby facilitating gas exchange through the eggshell even when the egg is submerged under water.

Tunneling Nanoelectromechanical Switches Based on Compressible Molecular Thin Films.

Abrupt switching behavior and near-zero leakage current of nanoelectromechanical (NEM) switches are advantageous properties through which NEMs can outperform conventional semiconductor electrical switches. To date, however, typical NEMs structures require high actuation voltages and can prematurely fail through permanent adhesion (defined as stiction) of device components. To overcome these challenges, in the present work we propose a NEM switch, termed a "squitch," which is designed to electromechanically modulate the tunneling current through a nanometer-scale gap defined by an organic molecular film sandwiched between two electrodes. When voltage is applied across the electrodes, the generated electrostatic force compresses the sandwiched molecular layer, thereby reducing the tunneling gap and causing an exponential increase in the current through the device. The presence of the molecular layer avoids direct contact of the electrodes during the switching process. Furthermore, as the layer is compressed, the increasing surface adhesion forces are balanced by the elastic restoring force of the deformed molecules which can promote zero net stiction and recoverable switching. Through numerical analysis, we demonstrate the potential of optimizing squitch design to enable large on-off ratios beyond 6 orders of magnitude with operation in the sub-1 V regime and with nanoseconds switching times. Our preliminary experimental results based on metal-molecule-graphene devices suggest the feasibility of the proposed tunneling switching mechanism. With optimization of device design and material engineering, squitches can give rise to a broad range of low-power electronic applications.

Molecular and morphological differentiation of testes and ovaries in relation to the thermosensitive period of gonad development in the snapping turtle, Chelydra serpentina.

Ambient temperatures during embryonic development determine gonadal sex in many reptiles. The temperature sensitive period for sex determination has been defined by shifting eggs between female- and male-producing temperatures in a few species. This phase spans 20-35% of embryogenesis in most species, which makes it difficult to define the mechanisms that transduce temperature into a signal for ovarian versus testicular development. We present an extensive set of studies that define a brief period when high temperature specifies, and then determines, ovarian fate in a northern population of snapping turtles, Chelydra serpentina. We shifted embryos from male to female temperatures, or vice versa, at various stages of development. Gonads in embryos incubated at female temperatures commit to ovarian fate earlier (by stage 18) than gonads in embryos incubated at male temperatures commit to testicular fate (by stages 19-21). In double shift studies, embryos were incubated at a female temperature, exposed to a male temperature for set times, and shifted back to the original temperature, or vice versa. The time required to induce ovarian development (≤6 days at female temperatures) was much shorter than the time required to induce testicular formation (>20 days at male temperatures). Differentiation of the gonads at the histological level occurred after the sex-determining period. Nevertheless, we found that a change in temperature rapidly (within 24h) influenced expression and splicing of WT1 mRNA: the absolute abundance of WT1 mRNA, the relative abundance of +KTS versus -KTS isoforms, as well as the ratio of +KTS:-KTS isoforms was higher in gonads at a male versus a female temperature. In conclusion, ovarian fate is more readily determined than testicular fate in snapping turtle embryos. The short sex-determining period in this species (6-8% of embryogenesis) will facilitate studies of molecular mechanisms for specification and determination of gonad fate by temperature.

The good, the bad, and the ugly: agonistic behaviour in juvenile crocodilians.

We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5-15 seconds), and occurred between 1600-2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae; and, side head striking combined with tail wagging by C. porosus. The two long-snouted species (C. johnstoni and G. gangeticus) avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae) appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes.

MMP9 regulates the cellular response to inflammation after skeletal injury.

Like other tissue injuries, bone fracture triggers an inflammatory response, which plays an important role in skeletal repair. Inflammation is believed to have both positive and negative effects on bone repair, but the underlying cellular mechanisms are not well understood. To assess the role of inflammation on skeletal cell differentiation, we used mouse models of fracture repair that stimulate either intramembranous or endochondral ossification. In the first model, fractures are rigidly stabilized leading to direct bone formation, while in the second model, fracture instability causes cartilage and bone formation. We compared the inflammatory response in these two mechanical environments and found changes in the expression patterns of inflammatory genes and in the recruitment of inflammatory cells and osteoclasts. These results suggested that the inflammatory response could influence skeletal cell differentiation after fracture. We then exploited matrix metalloproteinase 9 (MMP9) that is expressed in inflammatory cells and osteoclasts, and which we previously showed is a potential regulator of cell fate decisions during fracture repair. Mmp9(-/-) mice heal stabilized fractures via endochondral ossification, while wild type mice heal via intramembranous ossification. In parallel, we observed increases in macrophages and T cells in the callus of Mmp9(-/-) compared to wild type mice. To assess the link between the profile of inflammatory cells and skeletal cell fate functionally, we transplanted Mmp9(-/-) mice with wild type bone marrow, to reconstitute a wild type hematopoietic lineage in interaction with the Mmp9(-/-) stroma and periosteum. Following transplantation, Mmp9(-/-) mice healed stabilized fractures via intramembranous ossification and exhibited a normal profile of inflammatory cells. Moreover, Mmp9(-/-) periosteal grafts healed via intramembranous ossification in wild type hosts, but healed via endochondral ossification in Mmp9(-/-) hosts. We observed that macrophages accumulated at the periosteal surface in Mmp9(-/-) mice, suggesting that cell differentiation in the periosteum is influenced by factors such as BMP2 that are produced locally by inflammatory cells. Taken together, these results show that MMP9 mediates indirect effects on skeletal cell differentiation by regulating the inflammatory response and the distribution of inflammatory cells, leading to the local regulation of periosteal cell differentiation.

Magnetic pancreaticobiliary stents and retrieval system: obviating the need for repeat endoscopy (with video).

BACKGROUND: Plastic stents are routinely placed in the pancreaticobiliary system to facilitate drainage. A second endoscopy is often required for stent removal. We have developed magnetic pancreaticobiliary stents that can be removed by using an external hand-held magnet, thereby obviating the need for a second endoscopy. OBJECTIVE: To develop and test magnetic pancreaticobiliary stents and retrieval system in ex-vivo and in-vivo porcine models. SETTING: Animal laboratory. DESIGN: Benchtop and animal study. ANIMALS: 5 pigs. INTERVENTIONS: Design: Computer simulations determined both the optimal design of cylindrical magnets attached to the distal aspect of existing plastic stents and the optimal design of the external hand-held magnet. Benchtop ex-vivo experiments measured magnetic force to validate the design. In-vivo analysis: In 5 Yorkshire pigs, magnetic stents were deployed into the common bile duct by using a conventional duodenoscope. An external hand-held magnet was applied for stent removal. Stent insertion and removal times were recorded. MAIN OUTCOME MEASUREMENTS: Technical feasibility. RESULTS: Magnetic stents of varying lengths and calibers were successfully created. In ex-vivo testing, the capture distance was 10.0 cm. During in-vivo testing, the magnetic stents were inserted and removed easily. The mean insertion and removal times were 3.2 minutes and 33 seconds, respectively. LIMITATIONS: Animal study, small numbers. CONCLUSIONS: Magnetic pancreaticobiliary stents and associated retrieval system were successfully designed and tested in the acute porcine model. An external, noninvasive means of stent removal potentially obviates the need for a second endoscopy, which could represent a major gain both for patients and in health care savings.

Wireless stimulation of antennal muscles in freely flying hawkmoths leads to flight path changes.

Insect antennae are sensory organs involved in a variety of behaviors, sensing many different stimulus modalities. As mechanosensors, they are crucial for flight control in the hawkmoth Manduca sexta. One of their roles is to mediate compensatory reflexes of the abdomen in response to rotations of the body in the pitch axis. Abdominal motions, in turn, are a component of the steering mechanism for flying insects. Using a radio controlled, programmable, miniature stimulator, we show that ultra-low-current electrical stimulation of antennal muscles in freely-flying hawkmoths leads to repeatable, transient changes in the animals' pitch angle, as well as less predictable changes in flight speed and flight altitude. We postulate that by deflecting the antennae we indirectly stimulate mechanoreceptors at the base, which drive compensatory reflexes leading to changes in pitch attitude.

Smart Self-Assembling MagnetS for ENdoscopy (SAMSEN) for transoral endoscopic creation of immediate gastrojejunostomy (with video).

BACKGROUND: Gastrojejunostomy is important for palliation of malignant gastric outlet obstruction and surgical obesity procedures. A less-invasive endoscopic technique for gastrojejunostomy creation is conceptually attractive. Our group has developed a compression anastomosis technology based on endoscopically delivered self-assembling magnets for endoscopy (SAMSEN) to create an instant, large-caliber gastrojejunostomy. OBJECTIVE: To develop and evaluate an endoscopic means of gastrojejunostomy creation by using SAMSEN. SETTING: Developmental laboratory and animal facility. DESIGN: Animal study and human cadaveric study. SUBJECTS: Yorkshire pigs (7 cadaver, 5 acute); human (1 cadaver). INTERVENTIONS: A transoral procedure for SAMSEN delivery was developed in porcine and human cadaver models. Subsequently, gastrojejunostomy creation by using SAMSEN was performed in 5 acute pigs. The endoscope was advanced into the peritoneal cavity through the gastrotomy, and a segment of the small bowel was grasped and pulled closer to the stomach. An enterotomy was created, and a custom overtube was advanced into the small bowel for deployment of the first magnetic assembly. Next, a reciprocal magnetic assembly was deployed in the stomach. The 2 magnetic systems were mated under fluoroscopic and endoscopic guidance. Contrast studies assessed for gastrojejunostomy leak. Immediate necropsies were performed. MAIN OUTCOME MEASUREMENTS: Technical feasibility and complications. RESULTS: Gastrojejunostomy creation by using SAMSEN was successful in all 5 animals. Deep enteroscopy was performed through the stoma without difficulty. No leaks were identified on contrast evaluation. At necropsy, the magnets were properly deployed and robustly coupled together, resistant to vigorous tissue manipulation. LIMITATIONS: Acute animal study. CONCLUSIONS: Endoscopic creation of immediate gastrojejunostomy by using SAMSEN is technically feasible.