The oral route is the most common choice for drug administration because of several advantages, such as convenience, low cost, and high patient compliance, and the demand and investment in research and development for oral drugs continue to grow. The rate of dissolution and gastric emptying of the dissolved active pharmaceutical ingredient (API) into the duodenum is modulated by gastric motility, physical properties of the pill, and the contents of the stomach, but current in vitro procedures for assessing dissolution of oral drugs are limited in their ability to recapitulate this process. This is particularly relevant for disease conditions, such as gastroparesis, that alter the anatomy and/or physiology of the stomach. In silico models of gastric biomechanics offer the potential for overcoming these limitations of existing methods. In the current study, we employ a biomimetic in silico simulator based on the realistic anatomy and morphology of the stomach (referred to as “StomachSim”) to investigate and quantify the effect of body posture and stomach motility on drug bioavailability. The simulations show that changes in posture can potentially have a significant (up to 83%) effect on the emptying rate of the API into the duodenum. Similarly, a reduction in antral contractility associated with gastroparesis can also be found to significantly reduce the dissolution of the pill as well as emptying of the API into the duodenum. The simulations show that for an equivalent motility index, the reduction in gastric emptying due to neuropathic gastroparesis is larger by a factor of about five compared to myopathic gastroparesis.
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This content will become publicly available on January 1, 2025
In silico modelling of the effect of pyloric intervention procedures on gastric flow and emptying in a stomach with gastroparesis
Pyloric interventions are surgical procedures employed to increase the gastric emptying rate in gastroparesis patients. In this study, we use an
- Award ID(s):
- 2019405
- PAR ID:
- 10511192
- Publisher / Repository:
- Royal Society Publishing
- Date Published:
- Journal Name:
- Journal of The Royal Society Interface
- Volume:
- 21
- Issue:
- 210
- ISSN:
- 1742-5662
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Linked rhythmic behaviors, such as respiration/locomotion or swallowing/chewing, often require coordination for proper function. Despite its prevalence, the cellular mechanisms controlling coordination of the underlying neural networks remain undetermined in most systems. We use the stomatogastric nervous system of the crab
Cancer borealis to investigate mechanisms of internetwork coordination, due to its small, well-characterized feeding-related networks (gastric mill [chewing, ∼0.1 Hz]; pyloric [filtering food, ∼1 Hz]). Here, we investigate coordination between these networks during the Gly1-SIFamide neuropeptide modulatory state. Gly1-SIFamide activates a unique triphasic gastric mill rhythm in which the typically pyloric-only LPG neuron generates dual pyloric-plus gastric mill-timed oscillations. Additionally, the pyloric rhythm exhibits shorter cycles during gastric mill rhythm-timed LPG bursts, and longer cycles during IC, or IC plus LG gastric mill neuron bursts. Photoinactivation revealed that LPG is necessary to shorten pyloric cycle period, likely through its rectified electrical coupling to pyloric pacemaker neurons. Hyperpolarizing current injections demonstrated that although LG bursting enables IC bursts, only gastric mill rhythm bursts in IC are necessary to prolong the pyloric cycle period. Surprisingly, LPG photoinactivation also eliminated prolonged pyloric cycles, without changing IC firing frequency or gastric mill burst duration, suggesting that pyloric cycles are prolonged via IC synaptic inhibition of LPG, which indirectly slows the pyloric pacemakers via electrical coupling. Thus, the same dual-network neuron directly conveys excitation from its endogenous bursting and indirectly funnels synaptic inhibition to enable one network to alternately decrease and increase the cycle period of a related network. -
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Background Aspirin‐exacerbated respiratory disease (AERD) is the triad of asthma, nasal polyposis, and sensitivity to cyclooxygenase‐1 inhibitors. Treatment options include medical management, surgical intervention, and aspirin desensitization (AsaD).
Methods AERD patients were identified using the MarketScan Database from 2009 to 2015. Patients were included using International Classification of Diseases, 9th edition (ICD‐9) codes for asthma, nasal polyposis, and drug allergy. Treatments were determined by Current Procedural Terminology (CPT) codes for drug desensitization and endonasal procedures. Geographic trends and timing of interventions between those exposed and not exposed to desensitization were explored.
Results A total of 5628 patients met inclusion criteria for AERD, with mean age 46 years, 60% female; 395 (7%) underwent AsaD and 2171 (39%) underwent sinus surgery. Among patients who were desensitized, 229 (58%) underwent surgery, of whom 201 (88%) had surgery prior to AsaD (median [quartile 1, quartile 3]; 61 days [30, 208] prior to desensitization). For patients undergoing surgery following AsaD (n = 46), surgery was performed a median of 302 (163, 758) days after AsaD. Nineteen patients had multiple surgeries post‐AsaD with median time between surgeries being 734 days (312, 1484); 261 patients were not desensitized to aspirin but did undergo multiple surgeries, with the median of the median time between surgeries being 287 days (15, 617), which is shorter than for patients post‐AsaD (
p < 0.001).Conclusion A very small percentage of AERD patients undergo AsaD. Patients who had AsaD underwent surgery approximately 2 months prior to AsaD. Patients who underwent AsaD experienced an increased time between surgeries compared to patients who did not undergo AsaD.
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The peristaltic motion of stomach walls combines with the secretion of digestive enzymes to initiate the process that breaks down food. In this study, the mixing, breakdown, and emptying of a liquid meal containing protein is simulated in a model of a human stomach. In this model, pepsin, the gastric enzyme responsible for protein hydrolysis, is secreted from the proximal region of the stomach walls and allowed to react with the contents of the stomach. The velocities of the retropulsive jet induced by the peristaltic motion, the emptying rate, and the extent of hydrolysis are quantified for a control case as well as for three other cases with reduced motility of the stomach, which may result from conditions such as diabetes mellitus. This study quantifies the effect of stomach motility on the rate of food breakdown and its emptying into the duodenum and we correlate these observations with the mixing in the stomach induced by the wall motion.more » « less
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Network flexibility is important for adaptable behaviors. This includes neuronal switching, where neurons alter their network participation, including changing from single- to dual-network activity. Understanding the implications of neuronal switching requires determining how a switching neuron interacts with each of its networks. Here, we tested 1) whether “home” and second networks, operating via divergent rhythm generation mechanisms, regulate a switching neuron, and 2) if a switching neuron, recruited via modulation of intrinsic properties, contributes to rhythm or pattern generation in a new network. Small, well-characterized feeding-related networks (pyloric, ~1 Hz; gastric mill, ~0.1 Hz) and identified modulatory inputs make the isolated crab (Cancer borealis) stomatogastric nervous system (STNS) a useful model to study neuronal switching. In particular, the neuropeptide Gly1-SIFamide switches the lateral posterior gastric (LPG) neuron (2 copies) from pyloric-only to dual-frequency pyloric/gastric mill (fast/slow) activity via modulation of LPG intrinsic properties. Using current injections to manipulate neuronal activity, we found that gastric mill, but not pyloric, network neurons regulated the intrinsically generated LPG slow bursting. Conversely, selective elimination of LPG from both networks using photoinactivation revealed that LPG regulated gastric mill neuron firing frequencies but was not necessary for gastric mill rhythm generation or coordination. However, LPG alone was sufficient to produce a distinct pattern of network coordination. Thus, modulated intrinsic properties underlying dual-network participation may constrain which networks can regulate switching neuron activity. Further, recruitment via intrinsic properties may occur in modulatory states where it is important for the switching neuron to actively contribute to network output.
