Individual variations in mucosa and total wall thickness in the stomach and rectum assessed via endoscopic ultrasound

Evaluation of tissue blood supply during esophagectomy using fluorescent diagnostics and diffuse scattering spectroscopy in visible region

BACKGROUND

The success of the surgical treatment of a tumor or obstruction of the esophagus with subsequent anastomosis application depends on the level of blood supply to the stitched tissues. Intraoperative assessment of blood flow is widely used in medicine and can be used as a diagnostic method that affects the outcome of surgery and reduces the frequency of postoperative complications for the patient.

METHODS

In this work, the assessment of blood supply during esophageal resection operations was carried out using two techniques sequentially: fluorescent diagnostics with indocyanine green and measurement of hemoglobin oxygen saturation by diffuse scattering spectroscopy in the visible wavelength range. The first method was used to assess the integrity of the vascular network structure in the area of anastomosis and blood flow through the sutured tissues, the second one - for local assessment of hemoglobin oxygen saturation in the investigated area.

RESULTS

Conducted clinical study involved the participation of nine patients with malignant neoplasms (six cases) or esophageal obstruction (three cases). The presence of postoperative complications was compared with the measurement results. Anastomosis failure was observed in only one patient. According to the results of the study, with the use of the investigated method of assessing blood supply, there is a tendency towards a decrease in the frequency of anastomosis leaks (11.1 % compared with 21.4 %).

CONCLUSIONS

Therefore, fluorescent diagnostics with indocyanine green and measurement of hemoglobin oxygen saturation using diffuse scattering spectroscopy were affirmed as methods that allow increasing the safety of surgical procedures by assessing the risk of postoperative complications, including anastomosis failures.

Noninvasive and Microinvasive Nanoscale Drug Delivery Platforms for Hard Tissue Engineering

Bone tissue plays a crucial role in protecting internal organs and providing structural support and locomotion of the body. Treatment of hard tissue defects and medical conditions due to physical injuries, genetic disorders, aging, metabolic syndromes, and infections is more often a complex and drawn out process. Presently, dealing with hard-tissue-based clinical problems is still mostly conducted via surgical interventions. However, advances in nanotechnology over the last decades have led to shifting trends in clinical practice toward noninvasive and microinvasive methods. In this review article, recent advances in the development of nanoscale platforms for bone tissue engineering have been reviewed and critically discussed to provide a comprehensive understanding of the advantages and disadvantages of noninvasive and microinvasive methods for treating medical conditions related to hard tissue regeneration and repair.

Hydrogels for Mucosal Drug Delivery

Mucosal tissues are often a desirable site of drug action to treat disease and engage the immune system. However, systemically administered drugs suffer from limited bioavailability in mucosal tissues where technologies to enable direct, local delivery to these sites would prove useful. In this Spotlight on Applications article, we discuss hydrogels as an attractive means for local delivery of therapeutics to address a range of conditions affecting the eye, nose, oral cavity, gastrointestinal, urinary bladder, and vaginal tracts. Considering the barriers to effective mucosal delivery, we provide an overview of the key parameters in the use of hydrogels for these applications. Finally, we highlight recent work demonstrating their use for inflammatory and infectious diseases affecting these tissues.

Point-of-care Ultrasound of the Gastrointestinal Tract

The widespread use of portable ultrasound scanners has promoted the concept of point of care ultrasound (POCUS), namely "ultrasound performed bedside and interpreted directly by the clinician." The purpose of this short review is to outline how POCUS can be used in patients with diseases of the gastrointestinal (GI) tract. POCUS is not a replacement for comprehensive ultrasound, but rather allows physicians immediate access to clinical imaging for rapid diagnosis and efficient work-up and treatment of the patients. There are many indications for doing POCUS of the GI tract, including abdominal pain, diarrhea, palpable masses, and to detect fluid or free air in the abdominal cavity. To improve the visibility of deeper parts of the abdomen, the graded compression technique with the scan head is useful. During POCUS, the operator should look for signs of severe pathology including target lesions, the pseudo-kidney sign, the onion sign, dilated bowel loops, gastric retention, free fluid, and free air, depending on the actual clinical problem. We conclude that POCUS of the GI tract is very useful to provide a rapid diagnosis in many clinical scenarios.

Chronic Pain and the Endocannabinoid System: Smart Lipids - A Novel Therapeutic Option?

The development of a high-end cannabinoid-based therapy is the result of intense translational research, aiming to convert recent discoveries in the laboratory into better treatments for patients. Novel compounds and new regimes for drug treatment are emerging. Given that previously unreported signaling mechanisms for cannabinoids have been uncovered, clinical studies detailing their high therapeutic potential are mandatory. The advent of novel genomic, optogenetic, and viral tracing and imaging techniques will help to further detail therapeutically relevant functional and structural features. An evolutionarily highly conserved group of neuromodulatory lipids, their receptors, and anabolic and catabolic enzymes are involved in a remarkable variety of physiological and pathological processes and has been termed the endocannabinoid system (ECS). A large body of data has emerged in recent years, pointing to a crucial role of this system in the regulation of the behavioral domains of acquired fear, anxiety, and stress-coping. Besides neurons, also glia cells and components of the immune system can differentially fine-tune patterns of neuronal activity. Dysregulation of ECS signaling can lead to a lowering of stress resilience and increased incidence of psychiatric disorders. Chronic pain may be understood as a disease process evoked by fear-conditioned nociceptive input and appears as the dark side of neuronal plasticity. By taking a toll on every part of your life, this abnormal persistent memory of an aversive state can be more damaging than its initial experience. All strategies for the treatment of chronic pain conditions must consider stress-related comorbid conditions since cognitive factors such as beliefs, expectations, and prior experience (memory of pain) are key modulators of the perception of pain. The anxiolytic and anti-stress effects of medical cannabinoids can substantially modulate the efficacy and tolerability of therapeutic interventions and will help to pave the way to a successful multimodal therapy. Why some individuals are more susceptible to the effects of stress remains to be uncovered. The development of personalized prevention or treatment strategies for anxiety and depression related to chronic pain must also consider gender differences. An emotional basis of chronic pain opens a new horizon of opportunities for developing treatment strategies beyond the repeated sole use of acutely acting analgesics. A phase I trial to determine the pharmacokinetics, psychotropic effects, and safety profile of a novel nanoparticle-based cannabinoid spray for oromucosal delivery highlights a remarkable innovation in galenic technology and urges clinical studies further detailing the huge therapeutic potential of medical cannabis (Lorenzl et al.; this issue).

Efficacy and safety of a thermosensitive hydrogel for endoscopic submucosal dissection: An in vivo swine study

Injectable thermo-sensitive chitosan hydrogels have recently been developed for the use of submucosal fluids in endoscopic submucosal dissections (ESD). This study aimed to investigate the efficacy and safety of chitosan hydrogels during ESD. Submucosal fluids were administered as follows: 0.9% normal saline (NS), 0.4% hyaluronic acid (HA) and chitosan/β-glycerophosphate (CS/GP) hydrogel. Each solution was administered twice into the stomach and colon of a pig, with a total of 72 ESD procedures performed on 12 pigs. The injected volume and procedure-related parameters were recorded and analyzed. ESDs that created ulcers after 7 days were histologically compared. All ESD specimens were resected en bloc. The total injected volumes during ESD of the stomach (NS, 16.09±3.27 vs. HA, 11.17±2.32 vs. CS/GP, 9.44±2.33; p<0.001) and colon (NS, 9.17±1.80 vs. HA, 6.67±1.50 vs. CS/GP, 6.75±1.57; p = 0.001) were significantly different. Hydrogel showed significant differences from normal saline in terms of fluid power (mm²/vol; NS, 35.70±9.00 vs. CS/GP 57.48±20.77; p = 0.001) and consumption rate (vol/min; NS, 2.59±0.86 vs. CS/GP, 1.62±0.65; p = 0.013) in the stomach. Histological examination revealed preserved muscularis propria, although the chitosan hydrogel resulted in a partial inflammatory response, with a hypertrophied submucosal layer. Chitosan hydrogel was found to be superior to normal saline, with an efficacy similar to that of hyaluronic acid. Nonetheless, long-term histological changes should be evaluated before clinical implementation.

High-resolution photoacoustic/ultrasound imaging of the porcine stomach wall: an ex vivo feasibility study

Photoacoustic (PA) imaging has become invaluable in preclinical and clinical research. Endoscopic PA imaging in particular has been explored as a noninvasive imaging modality to view vasculature and diagnose cancers in the digestive system. However, these feasibility studies are still limited to rodents or rabbits. Here, we develop a fully synchronized simultaneous ultrasound and photoacoustic microscopy system using two spectral bands (i.e., the visible and near-infrared) in both optical- and acoustic-resolution modes. We investigate the feasibility of imaging gastric vasculature in an ex vivo porcine model. The entire gastric wall, including the mucosa, submucosa, muscularis propria, and serosa, was excised from fresh porcine stomachs immediately followed by ultrasound and PA imaging being performed within a few hours of sacrifice. PA images of the mucosal vasculature were obtained at depths of 1.90 mm, which is a clinically significant accomplishment considering that the average thickness of the human mucosa is 1.26 mm. The layer structure of the stomach wall could be clearly distinguished in the overlaid PA and US images. Because gastric cancer starts from the mucosal surface and infiltrates into the submucosa, PA imaging can cover a clinically relevant depth in early gastric cancer diagnosis. We were able to detect mucosal vasculature in the entire mucosal layer, suggesting the potential utility of combined PA/US imaging in gastroenterology.

Mixing and emptying of gastric contents in human-stomach: A numerical study

Stomach is one of the most important organs in human gastro-track. To better understand the operation of human-stomach, the process of mixing and emptying of gastric contents is simulated using a numerical method. The numerical results confirm that a fast pathway is located close to the lesser curvature of the stomach when water is emptied. However, this fast pathway doesn't exist when the gastric contents are composed of water and food boluses with different properties. The muscle contractions enhance the mixing of light food boluses and water, while they have limited effects on heavy food boluses. As a result, the foods are distributed in layers; heavy food boluses are located in the bottom layer. Besides the gastric motility and high viscosity of foods, the food matrix made of heavy food particles is also important to the formation of the Magenstrasse (stomach road). The food matrix and the zone of wrinkles behave like a porous medium which has higher flow resistance to the light food particles than to the water, leading to faster emptying of water. The water is emptied along the stomach wall since the flow resistance in the stomach wrinkles is smaller than the one in the food matrix. This mechanism is supported by the numerical results, while it might interpret the phenomena observed in the experiments.

Transmural Temperature Monitoring to Quantify Thermal Conduction And Lesion Formation During Gastric Ablation, an Emerging Therapy for Gastric Dysrhythmias

Gastric ablation is emerging as a potential therapy for electrical dysrhythmias associated with gastric disorders. Thermal conduction properties of gastric tissue during ablation have not yet been defined, but are necessary for optimizing the technique and translating ablation to clinical therapy. We developed custom needle-based transmural temperature probes to quantify the temperature of gastric tissue during ablation. These probes were applied in vivo in pigs (n=5), during gastric ablation (70 °C, 10 s duration), at distances of 2.5 - 20 mm from the ablation catheter tip. Thermal response of the tissue was non-linear; the maximum temperature increase from baseline (33.3 ± 1.0 °C) was observed at the closest temperature probe to the catheter tip (2.5 mm, 14.9 °C), and temperature change decreased with distance from the catheter tip. Probes positioned between 5 -20 mm from the catheter tip recorded temperature increases of less than 5.6 °C. This study provides methods for monitoring temperature during in vivo ablation, and demonstrates that functional temperature increases from ablation were restricted to within approximately 5 mm of the catheter. These methods can now be applied to optimize effective ablation parameters, and to inform models of gastric ablation.

A Miniaturized Capsule Endoscope Equipped a Marking Module for Intestinal Tumor Localization

This study introduces a miniaturized capsule endoscope equipped with a marking module for intestinal tumor or lesion localization. The design concept is based on an active wireless capsule endoscope platform that is manipulated by an external electromagnetic actuation (EMA) system. The magnetic response of a permanent magnet inside the capsule is designed to have flexible movement in viscous environment of bowel. This magnet is also utilized to activate tattooing process by triggering a gas-generated chemical reaction. Once approaching to a target region, gradient magnetic field from EMA system is induced to push magnet down, releasing water to dry chemical powder mixture. Then the gas pressure increases and pushes the piston move to inject ink into target point. During traveling in digestive organs, injection needle is stowed inside the capsule to avoid damage to the organs. The whole procedure is manipulated by EMA system, the injection consumes no internal battery and is observable through capsule's camera which provides clinician vision. Basic tests were conducted to evaluate the performance of proposed robotic capsule. The success of creating a black visible bled from serosa of intestine proves the feasibility and potential of the design. This study could be an alternative for traditional tattooing endoscopy and motivate other research groups for further development of functional wireless capsule endoscope.

A wireless tattooing capsule endoscope using external electromagnetic actuation and chemical reaction pressure

In this paper, we present a tattooing capsule endoscope (TCE) that can localize an intestinal lesion or tumor for a preoperative laparoscopic surgery. The TCE is based on a wireless capsule endoscope (WCE) structure and can be actively controlled by an external electromagnetic actuation system to move, observe, and mark the target lesion in the gastrointestinal (GI) tract. The TCE is designed to perform capsule locomotion, needle extrusion and intrusion motions, and ink injection. First, the TCE is controlled to move to the target lesion during GI tract diagnosis via a capsule endoscopic camera. Further, a tattooing needle is extruded by an electromagnetically controlled mechanism to puncture the tissue. Finally, the tattooing ink is injected by the chemically reacted carbon dioxide gas pressure that is triggered by a shape memory alloy wire and a reed switch. The reed switch is also activated by the external magnetic field flux density. The suggested methods were verified by the ex-vivo experiments. The TCE prototype was able to move to the target lesion and inject the ink beneath the mucosa layer safely, thereby leaving a visible tattooed mark for surgical lesion identification. The proposed TCE method can accelerate the development of functionalities as well as tattooing procedures of the WCE in the GI tract.

High frequency acoustic permeabilisation of drugs through tissue for localised mucosal delivery

The majority of infectious diseases enter the body through mucosal membranes that line the ocular, nasal, oral, vaginal and rectal surfaces. As infections can be effectively prevented by instigating a local immune response in the immunocyte-rich regions of the mucosa, an efficacious route of vaccine administration is to directly target their delivery to these surfaces. It is nevertheless challenging to provide sufficient driving force to penetrate both the mucus lining as well as the epithelial barrier of the mucosal surfaces, which are designed to effectively keep foreign entities out, but not excessively such that the therapeutic agent penetrates deeper into the vascularised submucosal regions where they are mostly taken up by the systemic circulation, thus resulting in a far weaker immune response. In this work, we demonstrate the possibility of controllably localising and hence maximising the delivery of both small and large molecule model therapeutic agents in the mucosa of a porcine buccal model using high frequency acoustics. Unlike their low (kHz order) frequency bulk ultrasonic counterpart, these high frequency (>10 MHz) surface waves do not generate cavitation, which leads to large molecular penetration depths beyond the 100 μm order thick mucosal layer, and which has been known to cause considerable cellular/tissue damage and hence scarring. Through system parameters such as the acoustic irradiation frequency, power and exposure duration, we show that it is possible to tune the penetration depth such that over 95% of the delivered drug are localised within the mucosal layer, whilst preserving their structural integrity.

Interleukin-6, tumor necrosis factor-alpha and receptor activator of nuclear factor kappa ligand are elevated in hypertrophic gastric mucosa of pachydermoperiostosis

Pachydermoperiostosis (PDP) is a rare inherited multisystem disease characterized with digital clubbing, pachydermia and periostosis. Variants in either HPGD or SLCO2A1 that interrupt the prostaglandin E2 (PGE₂) pathway have been shown to be involved in PDP. Here, in addition to six confirmed variants in HPGD or SLCO2A1, we identified four novel SLCO2A1 variants in eight PDP patients from seven Chinese Han families. In addition, gastric mucosa hyperplasia was observed in all affected individuals and interleukin-6 (IL-6), tumor necrosis factor-alpha (TNFα) and receptor activator of nuclear factor kappa ligand (RANKL) expression were elevated in hypertrophic gastric mucosa. Two of eight patients who had severe arthralgia were treated with celecoxib. After three months, their arthralgia was partly relieved and IL-6, TNFα and RANKL expression were decreased in accordance with their relieved hypertrophic gastric mucosa. Our study broadens the variation spectrum of SLCO2A1 and suggests that the gastric mucosa hyperplasia might be a common characteristic of PDP. Moreover, celecoxib would be a considerable choice for PDP patients. We also revealed that IL-6, TNFα and RANKL may play important roles in the molecular mechanisms of gastric mucosa hyperplasia in PDP for the first time.

Non-linear optical imaging and quantitative analysis of the pathological changes in normal and carcinomatous human colorectal muscularis

Non-linear optical (NLO) imaging based on two-photon excitation (2PE) and second harmonic generation (SHG) has been widely used to image microstructures of biomedical specimens over the last two decades. We employed NLO imaging technology to investigate the histology of normal and carcinomatous human colorectal muscularis in transverse and longitudinal views. Results show there are different patterns of pathological changes of muscularis in tissue structure and cell morphology from both views. The NLO imaging provides identical histological information as the H&E images but requires neither stain nor tissue processing. Our study indicates that NLO imaging technology shows more detailed microstructure, which is a critical complementary tool in pathological diagnosis of colorectal tumours. It suggests that NLO imaging could be a very important diagnostic tool to help pathologists realise the real time early detection of human colorectal tumours in the foreseeable future.

Anatomical variations of the stomach effects on electrogastrography

Routine screening and accurate diagnosis of chronic gastrointestinal motility disorders represents a significant problem in current clinical practice. Electrogastrography (EGG) provides a non-invasive option for assessing gastric slow waves, as a means of diagnosing gastric dysrhythmias. However, its uptake in motility practice has been limited partly due to an incomplete description of how the underlying gastric slow waves directly relate to EGG. This study aims to quantify the effects of various anatomical orientations of the stomach on EGG using a multiscale model of whole-organ slow wave activation and EGG. The orientation of the stomach was perturbed over six parameters: x, y, z translations and rotations. The perturbed simulations were compared to the original simulated model using root-mean-squared (RMS) errors and correlation coefficients. Simulations demonstrated that the perturbations had minimal influence on EGG, however channels located within close proximity of the stomach source were subject to large variation as a result of the perturbations. The results indicate that outside a critical area the effects of translation/rotation have minimal influence on the EGG, and thus beyond this critical area findings should be relatively comparable across patient groups. These findings show promise in advancing rational development of improved EGG methods towards a normative methodology and the formation of a normative database.

A Theoretical Analysis of Electrogastrography (EGG) Signatures Associated With Gastric Dysrhythmias

Routine screening and accurate diagnosis of chronic gastrointestinal motility disorders represent a significant problem in current clinical practice. The electrogastrography (EGG) provides a noninvasive option for assessing gastric slow waves, as a means of diagnosing gastric dysrhythmias, but its uptake in motility practice has been limited partly due to an incomplete sensitivity and specificity. This paper presents the development of a human whole-organ gastric model to enable virtual (in silico) testing of gastric electrophysiological dispersion in order to improve the diagnostic accuracy of EGG. The model was developed to simulate normal gastric slow wave conduction as well as three types of dysrhythmias identified in recent high-resolution gastric mapping studies: conduction block, re-entry, and ectopic pacemaking. The stomach simulations were then applied in a torso model to identify predicted EGG signatures of normal and dysrhythmic slow wave profiles. The resulting EGG data were compared using percentage differences and correlation coefficients. Virtual EGG channels that demonstrated a percentage difference over 100% and a correlation coefficient less than ±0.2 (threshold relaxed to ±0.5 for the ectopic pacemaker case) were further investigated for their specific distinguishing features. In particular, anatomical locations from the epigastric region and specific channel configurations were identified that could be used to clinically diagnose the three classes of human gastric dysrhythmia. These locations and channels predicted by simulations present a promising methodology for improving the clinical reliability and applications of EGG.

Oral uptake of nanoparticles: human relevance and the role of in vitro systems

Nanoparticles (NPs) present in environment, consumer and health products, food and medical applications lead to a high degree of human exposure and concerns about potential adverse effects on human health. For the general population, the exposure through contact with the skin, inhalation and oral uptake are most relevant. Since in vivo testing is only partly able to study the effects of human oral exposure, physiologically relevant in vitro systems are being developed. This review compared the three routes taking into account the estimated concentration, size of the exposed area, morphology of the involved barrier and translocation rate. The high amounts of NPs in food, the large absorption area and the relatively high translocation rate identified oral uptake as most important portal of entry for NPs into the body. Changes of NP properties in the physiological fluids, mechanisms to cross mucus and epithelial barrier, and important issues in the use of laboratory animals for oral exposure are mentioned. The ability of in vitro models to address the varying conditions along the oro-gastrointestinal tract is discussed, and requirements for physiologically relevant in vitro testing of orally ingested NPs are listed.

Cap-assisted EMR for rectal neuroendocrine tumors: comparisons with conventional EMR and endoscopic submucosal dissection (with videos)

BACKGROUND AND AIMS

The incidence of rectal neuroendocrine tumors (NETs) is increasing, and most small rectal NETs can be treated endoscopically. Cap-assisted EMR (EMR-C) was suggested as an effective treatment for rectal NETs in a few studies. We aimed to compare the outcomes of conventional EMR, EMR-C, and endoscopic submucosal dissection (ESD) for the treatment of rectal NETs.

METHODS

A total of 138 rectal NETs were treated endoscopically by a single endoscopist at Asan Medical Center. We analyzed 122 rectal NETs that had been removed by using EMR (n = 56), EMR-C (n = 34), or ESD (n = 32).

RESULTS

The histologic complete resection rate was higher in the EMR-C group than in the EMR group (94.1% vs 76.8%, P = .032). Intraprocedural bleeding tended to be more frequent in the EMR-C group than in the EMR group (8.8% vs 0%, P = .051). No differences in the rates of adverse events or histologic complete resections were observed between the EMR-C group and the ESD group for 6-mm to 8-mm NETs; however, the procedure time was significantly shorter in the EMR-C group (3.9 ± 1.1 minutes) than in the ESD group (19.0 ± 12.1 minutes) (P < .001). There was no recurrence in any of the 3 groups.

CONCLUSIONS

EMR-C is the preferable technique for endoscopic resection of small rectal NETs.

A Multiscale Tridomain Model for Simulating Bioelectric Gastric Pacing

GOAL

Gastric motility disorders have been associated with abnormal slow wave electrical activity (gastric dysrhythmias). Gastric pacing is a potential therapy for gastric dysrhythmias; however, new pacing protocols are required that can effectively modulate motility patterns, while being power efficient. This study presents a novel comprehensive 3-D multiscale modeling framework of the human stomach, including anisotropic conduction, capable of evaluating pacing strategies.

METHODS

A high-resolution anatomically realistic mesh was generated from CT images taken from a human stomach. Principal conduction axes were calculated and embedded within this model based on a modified Laplace-Dirichlet rule-based algorithm. A continuum-based tridomain formulation was implemented and evaluated for performance and used to model the slow-wave propagation, which takes into account the two main cell types present in gastric musculature. Model parameters were found by matching predicted normal slow-wave activity to experimental observation and data. These simulation parameters were applied while modeling an external pacing event to entrain slow-wave patterns.

RESULTS

The proposed formulation was found to be two times more efficient than a previous formulation for a normal slow-wave simulation. Convergence analysis showed that a mesh resolution of [Formula: see text] is required for an accurate solution process.

CONCLUSION

The effect of different pacing frequencies on entrainment demonstrated that the pacing protocols are limited by the frequency of the native propagation and the refractory period of the cellular activity.

SIGNIFICANCE

The model is expected to become an important tool in studying pacing protocols for both efficiency and effectiveness.

Predictive model of the prostate motion in the context of radiotherapy: A biomechanical approach relying on urodynamic data and mechanical testing

In this paper, a biomechanical approach relying on urodynamic data and mechanical tests is proposed for an accurate prediction of the motion of the pelvic organs in the context of the prostate radiotherapy. As a first step, an experimental protocol is elaborated to characterize the mechanical properties of the bladder and rectum wall tissues; uniaxial tensile tests are performed on porcine substrates. In a second step, the parameters of Ogden-type hyperelastic constitutive models are identified; their relevance in the context of the implementation of a human biomechanical model is verified by means of preliminary Finite Elements (FE) simulations against human urodynamic data. In a third step, the identified constitutive equations are employed for the simulations of the motion and interactions of the pelvic organs due to concomitant changes of the distension volumes of the urinary bladder and rectum. The effectiveness of the developed biomechanical model is demonstrated in investigating the motion of the bladder, rectum and prostate organs; the results in terms of displacements are shown to be in good agreement with measurements inherent to a deceased person, with a relative error close to 6%.

In vitro permeability of silver nanoparticles through porcine oromucosal membrane

Silver nanoparticles (AgNPs) can come in contact with human oral mucosa due to their wide use in food industry and hygiene devices. We evaluate transmucosal absorption of 19 nm AgNPs using excised porcine buccal mucosa applied on Franz diffusion cells. Two donor solutions were used: one containing AgNPs (0.5 g/L) and one derived from the ultrafiltration of the former and containing only Ag in its soluble form. Experiments were carried out separately for 4 h. Silver flux permeation was demonstrated through oral mucosa, showing similar values for AgNPs (6.8±4.5 ng cm(-2) h(-1)) and Ag ions (5.2±4.3 ng cm(-2) h(-1)). Our study demonstrates that silver can permeate the oromucosal barrier and that absorption is substantially due to Ag ions, since no permeation difference was found using the two solutions. Mucosal absorption has to be considered in further risk assessment studies.

Image-based noninvasive evaluation of colorectal mucosal injury in sheep after topical application of microbicides

BACKGROUND

Successful development of topical rectal microbicides requires preclinical evaluation in suitable large animal models. Our previous studies have demonstrated the benefits of high-resolution optical coherence tomography (OCT) to visualize subclinical microbicide toxicity in the sheep vagina. In the current study, we evaluated the potential application of colonoscopy and OCT to visualize and quantify the effects of topical products on sheep colorectal tissue, as assessed by advanced imaging techniques.

METHODS

Yearling virginal female sheep were treated rectally with a single 8-mL dose of 0.2% benzalkonium chloride (BZK) solution or phosphate-buffered saline control. Imaging was performed before and 30 minutes after treatment. Colonoscopy findings were evaluated based on mucosal disruption. Optical coherence tomography images were graded based on the integrity of the mucosal layer. Biopsies collected after treatment were evaluated by histology for validation of OCT scoring.

RESULTS

Mucosal disruption was observed by colonoscopy in BZK-treated animals, whereas none was present in controls. In contrast to colonoscopy, high-resolution in-depth OCT imaging provided visualization of the morphology of the mucosal layer and underlying muscularis, thus enabling detection of microscopic abnormalities. Noninvasive quantification of drug-induced injury after validation of the scoring system (categories 1, 2, 3) showed increased scores after treatment with BZK (P < 0.001), indicating mucosal injury.

CONCLUSIONS

High-resolution OCT can be used as highly sensitive tool to evaluate rectal microbicide effects. Because the sheep rectum has both gross and microscopic similarities to the human, this model is a useful addition to current methods of rectal product toxicity.

The bioelectrical basis and validity of gastrointestinal extracellular slow wave recordings

  Gastrointestinal extracellular recordings have been a core technique in motility research for a century. However, the bioelectrical basis of extracellular data has recently been challenged by claims that these techniques preferentially assay movement artifacts, cannot reproduce the underlying slow wave kinetics, and misrepresent the true slow wave frequency. These claims motivated this joint experimental-theoretical study, which aimed to define the sources and validity of extracellular potentials. In vivo extracellular recordings and video capture were performed in the porcine jejunum, before and after intra-arterial nifedipine administration. Gastric extracellular recordings were recorded simultaneously using conventional serosal contact and suction electrodes, and biphasic and monophasic extracellular potentials were simulated in a biophysical model. Contractions were abolished by nifedipine, but extracellular slow waves persisted, with unchanged amplitude, downstroke rate, velocity, and downstroke width (P>0.10 for all), at reduced frequency (24% lower; P=0.03). Simultaneous suction and conventional serosal extracellular recordings were identical in phase (frequency and activation-recovery interval), but varied in morphology (monophasic vs. biphasic; downstroke rate and amplitude: P<0.0001). Simulations demonstrated the field contribution of current flow to extracellular potential and quantified the effects of localised depolarisation due to suction pressure on extracellular potential morphology. In sum, these results demonstrate that gastrointestinal extracellular slow wave recordings cannot be explained by motion artifacts, and are of a bioelectrical origin that is highly consistent with the underlying biophysics of slow wave propagation. Motion suppression is shown to be unnecessary as a routine control in in vivo extracellular studies, supporting the validity of the extant gastrointestinal extracellular literature.

Titanium dioxide nanoparticles and the oral uptake-route

Titanium dioxide (TiO2) is a common additive that is increasingly used in consumer products, food, pharmaceutical dosage forms and cosmetic articles. However, due to size reduction of TiO2 particles from the microscale to the nanoscale, application areas of this material are expanding, especially in the food sector, which makes investigations of nano-TiO2 crucial. This review focuses on two important topics of current research regarding the oral pathway: 1) anatomy of the orogastrointestinal tract, composition of epithelial and mucus layer, and pH changes; 2) cell entry mechanisms, cytotoxicity and translocation. Sufficient knowledge on the oral uptake route is not yet available but is highly needed for human risk evaluation.

In-vitro permeability of neutral polystyrene particles via buccal mucosa

Drugs can be absorbed well in the oral cavity, which eliminates problems related to intestinal and hepatic first-pass metabolism. Although it is well-established that nanoparticles are small enough to penetrate/permeate epithelial barriers, there is no clear understanding of how they interact with the buccal mucosa. This work provides useful information regarding particle properties with regard to mucosal uptake and can be used for the rational design of nanocarriers. In the buccal mucosa, the uptake of neutral polystyrene nanoparticles (PP) is size-dependent. Compared to 25 and 50 nm particles, 200 nm PP particles penetrate into deeper regions of the mucosa. This is attributed to the structure of the buccal mucosa, i.e., mucus layer and microplicae. The particles permeate the mucus layer and deposit in ridge-like folds of superficial buccal cells. Thus, the effects of thermodynamic driving forces and/or interparticle electrostatic repulsion are enhanced and cellular uptake might be reduced for smaller particle sizes.

Risk of radiogenic second cancers following volumetric modulated arc therapy and proton arc therapy for prostate cancer

Prostate cancer patients who undergo radiotherapy are at an increased risk to develop a radiogenic second cancer. Proton therapy has been shown to reduce the predicted risk of second cancer when compared to intensity modulated radiotherapy. However, it is unknown if this is also true for the rotational therapies proton arc therapy and volumetric modulated arc therapy (VMAT). The objective of this study was to compare the predicted risk of cancer following proton arc therapy and VMAT for prostate cancer. Proton arc therapy and VMAT plans were created for three patients. Various risk models were combined with the dosimetric data (therapeutic and stray dose) to predict the excess relative risk (ERR) of cancer in the bladder and rectum. Ratios of ERR values (RRR) from proton arc therapy and VMAT were calculated. RRR values ranged from 0.74 to 0.99, and all RRR values were shown to be statistically less than 1, except for the value calculated with the linear-non-threshold risk model. We conclude that the predicted risk of cancer in the bladder or rectum following proton arc therapy for prostate cancer is either less than or approximately equal to the risk following VMAT, depending on which risk model is applied.

Rapid high-amplitude circumferential slow wave propagation during normal gastric pacemaking and dysrhythmias

BACKGROUND

Gastric slow waves propagate aborally as rings of excitation. Circumferential propagation does not normally occur, except at the pacemaker region. We hypothesized that (i) the unexplained high-velocity, high-amplitude activity associated with the pacemaker region is a consequence of circumferential propagation; (ii) rapid, high-amplitude circumferential propagation emerges during gastric dysrhythmias; (iii) the driving network conductance might switch between interstitial cells of Cajal myenteric plexus (ICC-MP) and circular interstitial cells of Cajal intramuscular (ICC-IM) during circumferential propagation; and (iv) extracellular amplitudes and velocities are correlated.

METHODS

An experimental-theoretical study was performed. High-resolution gastric mapping was performed in pigs during normal activation, pacing, and dysrhythmia. Activation profiles, velocities, and amplitudes were quantified. ICC pathways were theoretically evaluated in a bidomain model. Extracellular potentials were modeled as a function of membrane potentials.

KEY RESULTS

High-velocity, high-amplitude activation was only recorded in the pacemaker region when circumferential conduction occurred. Circumferential propagation accompanied dysrhythmia in 8/8 experiments was faster than longitudinal propagation (8.9 vs 6.9 mm s(-1) ; P = 0.004) and of higher amplitude (739 vs 528 μV; P = 0.007). Simulations predicted that ICC-MP could be the driving network during longitudinal propagation, whereas during ectopic pacemaking, ICC-IM could outpace and activate ICC-MP in the circumferential axis. Experimental and modeling data demonstrated a linear relationship between velocities and amplitudes (P < 0.001).

CONCLUSIONS & INFERENCES

The high-velocity and high-amplitude profile of the normal pacemaker region is due to localized circumferential propagation. Rapid circumferential propagation also emerges during a range of gastric dysrhythmias, elevating extracellular amplitudes and organizing transverse wavefronts. One possible explanation for these findings is bidirectional coupling between ICC-MP and circular ICC-IM networks.

Near infrared photonic finger imager for prostate cancer screening

A portable rectal near infrared (NIR) scanning polarization imaging unit with an optical fiber-based rectal probe, designated as a Photonic Finger (PF), was designed, developed, built and tested. PF was used to image and locate the three dimensional (3D) positions of abnormal prostate tissue embedded inside normal prostate tissue. An inverse image reconstruction algorithm, namely Optical Tomography using Independent Component Analysis (OPTICA) was developed to unmix the signal from targets (cancerous tissue) embedded in a turbid media (normal tissue) in the backscattering imaging geometry. The Photonic Finger combined with OPTICA was ex vivo tested to characterize different target(s) inside different tissue medium, including cancerous prostate tissue embedded inside large pieces of normal tissue. This new developed instrument, Photonic Finger, may provide an alternative imaging technique, which is accurate, of high spatial resolution and non-or-less invasive for prostate cancers screening.

Severe necrosis of oesophageal and gastric mucosa in fatal methanol poisoning

Methanol is a potent neurotoxic substance that causes severe metabolic acidosis and serious neurological disorders. Most of the cases are accidental exposures to drinking beverages contaminated with methanol. There are few articles reporting pure methanol intoxication; however, it is well known that small quantities of pure methanol causes blindness and death, the minimum lethal dose being 50-100 ml.A case report is presented of a 67-year-old woman, who committed suicide by ingestion of 500 ml of absolute methanol. Despite symptomatic and supportive intensive care, the woman died 23 h after hospital admission due to metabolic acidosis and multiple organ dysfunction syndrome. A complete medico-legal autopsy was performed. Grossly, there was complete detachment of the oesophagus mucosa and brownish discolouration of the gastric mucosa. Histological findings showed diffuse haemorrhagic necrosis of the stomach mucosa and intense acute inflammatory infiltration of the lamina propria. To our knowledge, this is the first autopsy report of such severe digestive injuries. A discussion and review of the recent literature on the subject are given.

Models for oral uptake of nanoparticles in consumer products

Presently, many consumer products contain nano-sized materials (NMs) to improve material properties, product quality and ease of use. NMs in food additives and in cosmetic articles (e.g., tooth paste) may be taken up by the oral route. As adverse effects of environmental nanoparticles, like ultrafine particles, have been reported, consumers worry about potential risks when using products containing NMs. The review focuses on metal and metal oxide NMs as common additives in tooth paste and in food industry and exposure by the oral route. Testing of NMs for oral exposure is very complex because differences in the diet, in mucus secretion and composition, in pH, in gastrointestinal transit time and in gastrointestinal flora influence NM uptake. Acellular (mucus, saliva) and epithelial layer of the orogastrointestinal barrier are described. Expected exposure doses, interaction of the NMs with mucus and permeation through the epithelium as well as in vivo data are mentioned. The role of in vitro models for the study of parameters relevant for ingested NMs is discussed.

A pilot study of transrectal endoscopic ultrasound elastography in inflammatory bowel disease

Background

Using standard diagnostic algorithms it is not always possible to establish the correct phenotype of inflammatory bowel disease which is essential for therapeutical decisions. Endoscopic ultrasound elastography is a new endoscopic procedure which can differentiate the stiffness of normal and pathological tissue by ultrasound. Therefore, we aimed to investigate the role of transrectal ultrasound elastography in distiction between Crohn's disease and ulcerative colitis.

Methods

A total 30 Crohn's disease, 25 ulcerative colitis, and 28 non-inflammatory bowel disease controls were included. Transrectal ultrasound elastography was performed in all patients and controls. In all ulcerative coltis patients and 80% of Crohn's disease patients endoscopy was performed to assess disease activity in the rectum.

Results

Significant difference in rectal wall thickness and strain ratio was detected between patients with Crohn's disease and controls (p = 0.0001). CD patients with active disease had higher strain ratio than patients in remission (p = 0.02). In ulcerative colitis group a significant difference in rectal wall thickness was found between controls and patients with active disease (p = 0.03). A significant difference in rectal wall thickness (p = 0.02) and strain ratio (p = 0.0001) was detected between Crohn's disease and ulcerative colitis patient group. Crohn's disease patients with active disease had a significantly higher strain ratio compared to ulcerative colitis patients with active disease (p = 0.0001).

Conclusion

Transrectal ultrasound elastography seems to be a promising new diagnostic tool in the field of inflammatory bowel disease. Further study on a larger cohort of patients is needed to definitely assess the role of transrectal ultrasound elastography in inflammatory bowel disease.

Study of rotational dynamics of receptor-targeted contrast agents in cancerous and normal prostate tissues using time-resolved picosecond emission spectroscopy

We studied the time-resolved polarization-dependent fluorescence spectroscopy of receptor-targeted contrast agents (Cybesin and Cytate) bound with prostate cancer cells in prostate tissue. An analytical model dealing with highly viscous tissue media was developed and used to investigate the rotation times and fluorescence anisotropies of the receptor-targeted contrast agents in prostate tissue. The differences of rotation times and fluorescence anisotropies were observed for Cybesin (Cytate) in cancerous and normal prostate tissues, which reflect changes of the microstructures of cancerous and normal tissues and their different bound affinity with contrast agents. The preferential uptake of Cytate (Cybesin) in cancerous tissue was used to image and distinguish cancerous tissue areas from normal tissue areas. The fluorescence polarization difference imaging technique was used to enhance the image contrast between the cancerous and normal tissue areas. This research may help to introduce a new optical approach and criteria for prostate cancer detection.

A multiscale model of the electrophysiological basis of the human electrogastrogram

The motility of the stomach is coordinated by an electrical activity termed "slow waves", and slow-wave dysrhythmias contribute to motility disorders. One major method for clinically evaluating gastric dysrhythmias has been electrogastrography (EGG); however, the clinical utility of EGG is limited partly due to the uncertainty regarding its electrophysiological basis. In this study, a multiscale model of gastric slow waves was generated from a biophysically based continuum description of cellular electrical events, coupled with a subject-specific human stomach model and high-resolution electrical mapping data. The model was then applied using a forward-modeling approach, within an anatomical torso model, to define how slow wave activity summates to generate the EGG potentials. The simulated EGG potentials were shown to be spatially varying in amplitude (0.27-0.33 mV) and duration (9.2-15.3 s), and the sources of this variance were quantified with respect to the activation timings of the underlying slow wave activity. This model constitutes an improved theory of the electrophysiological basis of the EGG, and offers a framework for optimizing the placement of EGG electrodes, and for interpreting the EGG changes occurring in disease states.

Changes of collagen and nicotinamide adenine dinucleotide in human cancerous and normal prostate tissues studied using native fluorescence spectroscopy with selective excitation wavelength

The fluorescence spectra of human cancerous and normal prostate tissues obtained by the selective excitation wavelength of 340 nm were measured. The contributions of principle biochemical components to tissue fluorescence spectra were investigated using the method of multivariate curve resolution with alternating least squares. The results show that there is a reduced contribution from the emission of collagen and increased contribution from nicotinamide adenine dinucleotide (NADH) in cancerous tissues as compared with normal tissue. This difference is attributed to the changes of relative contents of NADH and collagen during cancer development. This research may present a potential native biomarker for prostate cancer detection.

Ultrasound and inflammatory bowel disease

Transabdominal bowel sonography is a fast, efficient, and cheap way of examining the intestines. It is also virtually hazard-free and well accepted by patients. During the last 20 years, it has been established as a procedure for detecting bowel disease early in the diagnostic workup. Although rather unspecific, the method is sensitive for detection of bowel disease and can be applied to find the extent and location of inflammatory bowel disease. In patients with known ulcerative colitis and Crohn disease, it can also be used for follow-up because it is easily repeatable and radiation-free. Because it can be applied to find both intraluminal and peri-intestinal pathological features, it is a particularly valuable tool for the detection of complications of Crohn disease as stenosis, fistulas, and abscesses. Neither B-mode nor Doppler techniques have been proven obviously useful in categorizing disease activity, but new techniques using intravenous contrast might come closer to solving this question. Finally, recent longitudinal studies using transabdominal bowel sonography show that it can also give important prognostic information and be used for monitoring the effect of therapy.

Systematic review: ulcer definition in NSAID ulcer prevention trials

BACKGROUND

In clinical trials of peptic ulcer prevention, the most appropriate definition of an ulcer remains challenging.

AIMS

To evaluate the ulcer definitions used in clinical trials of ulcer prevention among non-steroidal anti-inflammatory drug users and to determine whether any specific definition is preferred.

METHODS

A systematic literature search of the PubMed, Medline and EMBASE databases was conducted. Results were limited to full papers published in English from June 1987 to June 2007 that met the following criteria: randomized, controlled non-steroidal anti-inflammatory drug trials of > or =8 weeks' duration, with a primary end point of ulcer upon endoscopy.

RESULTS

Forty five publications met the inclusion criteria and were reviewed. Overall, an ulcer diameter of > or =3 mm was used in 25 publications and most included a description of ulcer depth. Of the remainder, ulcer was defined as any lesion with unequivocal/observable depth (with no lower limit for ulcer diameter; five publications) or an excavated mucosal break >3 mm (one publication), whereas nine defined a minimum ulcer size of > or =5 or >5 mm. Ulcer definition was unclear in the remaining five publications.

CONCLUSION

In clinical trials of ulcer prevention among non-steroidal anti-inflammatory drug users, a gastric or duodenal lesion > or =3 mm in diameter with significant depth is the preferred definition.

Comparison and analysis of inter-subject variability of simulated magnetic activity generated from gastric electrical activity

Electrogastrograms (EGGs) produced from gastric electrical activity (GEA) are used as a non-invasive method to aid in the assessment of a subject's gastric condition. It has been documented that recordings of the magnetic activity generated from GEA are more reliable. Typically, with magnetic measurements of GEA, only activity perpendicular to the body is recorded. Also, external anatomical landmarks are used to position the magnetic recording devices, SQUIDs, (Superconducting Quantum Interference Devices) over the stomach with no allowance made for body habitus. In the work presented here, GEA and its corresponding magnetic activity are simulated. Using these data, we investigate the effects of using a standard SQUID location as well as a customized SQUID position and the contribution the magnetic component perpendicular to the body makes to the magnetic field. We also explore the effects of the stomach wall thickness on the resultant magnetic fields. The simulated results show that the thicker the wall, the larger the magnitude of the magnetic field holding the same signal patterns. We conclude that most of the magnetic activity arising from GEA occurs in a plane parallel to the anterior body. We also conclude that using a standard SQUID position can be suboptimal.

All fiber based multispeckle modality endoscopic system for imaging medical cavities

Disease detection in body cavities, such as the detection of abnormal growths in the colon path, has been illustrated here using an image fiber guided catheter based multispeckle modality endoscopic system. An all fiber-optic approach for the illumination and imaging of the inner cavity walls is adopted here. An endoscope probe to carry the illumination fibers as well as the imaging lens-image fiber unit is designed and custom fabricated in order to operate the probe in its various direction sensitive configurations. This is facilitated by the selection of suitable optical elements such as beam combiner and biprism at the probe proximal end. Experimental investigations were carried out using the endoscope system employing phantom model of colon as the test specimen that has normal and abnormal (representing growth) regions and the obtained results indicated the system effectiveness in identifying the abnormal growths at an early stage.

Using computed tomography scans to develop an ex-vivo gastric model

The objective of this research was to use abdominal computed tomography (CT) scans to non-invasively quantify anthropometrical data of the human stomach and to concomitantly create an anatomically correct and distensible ex-vivo gastric model. Thirty-three abdominal CT scans of human subjects were obtained and were imported into reconstruction software to generate 3D models of the stomachs. Anthropometrical data such as gastric wall thickness, gastric surface area and gastric volume were subsequently quantified. A representative 3D computer model was exported into a selective laser sintering (SLS) rapid prototyping machine to create an anatomically correct solid gastric model. Subsequently, a replica wax template of the SLS model was created. A negative mould was offset around the wax template such that the offset distance was equivalent to that of the gastric wall thickness. A silicone with similar mechanical properties to the human stomach was poured into the offset. The lost wax manufacturing technique was employed to create a hollow distensible stomach model. 3D computer gastric models were generated from the CT scans. A hollow distensible silicone ex-vivo gastric model with similar compliance to that of the human stomach was created. The anthropometrical data indicated that there is no significant relationship between BMI and gastric surface area or gastric volume. There were inter- and intra-group differences between groups with respect to gastric wall thickness. This study demonstrates that abdominal CT scans can be used to both non-invasively determine gastric anthropometrical data as well as create realistic ex-vivo stomach models.

Revisions to the ORNL series of adult and pediatric computational phantoms for use with the MIRD schema

The age-dependent series of stylized computational phantoms developed at the Oak Ridge National Laboratory in the late 1970's to early 1980's has found wide applicability in dosimetry studies ranging from dose coefficient compilations for external and internal photon emitters, simulations of patient radiological exams, and dose reconstruction activities. In the present study, we report on a series of revisions to the Oak Ridge National Laboratory series for their intended use within the MIRD schema of medical internal dosimetry. These revisions were made to (1) incorporate recent developments in stylized models of the head, brain, kidneys, rectosigmoid colon, and extra-pulmonary airways; (2) incorporate new models of the salivary glands and the mucosa layer of the urinary bladder, alimentary tract organs, and respiratory airways; (3) adopt reference values of elemental tissue compositions and mass densities from ICRP Publication 89 and ICRU Report 46; (4) provide for explicit treatment of left and right organs within organ pairs; (5) provide for a systematic tabulation of electron absorbed fractions as a function of energy and subject age for all internal organs; and (6) provide for methods of deriving patient-specific values of the specific absorbed fraction for both electrons and photons through interpolation/extrapolation of their phantom-derived values. While tomographic computational phantoms provide improved anatomic realism given the CT or MR image sets used in their construction, there does not yet exist a comprehensive series of reference pediatric tomographic phantoms, nor the ability to simulate very fine anatomic structures as can be modeled via mathematical approximation. Consequently, stylized pediatric phantoms will continue to fill this data need in medical dosimetry.